Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/fs/namespace.c |
| 3 | * |
| 4 | * (C) Copyright Al Viro 2000, 2001 |
| 5 | * Released under GPL v2. |
| 6 | * |
| 7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. |
| 8 | * Heavily rewritten. |
| 9 | */ |
| 10 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/syscalls.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/sched.h> |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 14 | #include <linux/spinlock.h> |
| 15 | #include <linux/percpu.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/init.h> |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 17 | #include <linux/kernel.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | #include <linux/acct.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 19 | #include <linux/capability.h> |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 20 | #include <linux/cpumask.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/module.h> |
Andrew Morton | f20a9ea | 2006-08-14 22:43:23 -0700 | [diff] [blame] | 22 | #include <linux/sysfs.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 23 | #include <linux/seq_file.h> |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 24 | #include <linux/mnt_namespace.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | #include <linux/namei.h> |
Alexey Dobriyan | b43f3cb | 2009-07-08 01:54:37 +0400 | [diff] [blame] | 26 | #include <linux/nsproxy.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | #include <linux/security.h> |
| 28 | #include <linux/mount.h> |
David Howells | 07f3f05c | 2006-09-30 20:52:18 +0200 | [diff] [blame] | 29 | #include <linux/ramfs.h> |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 30 | #include <linux/log2.h> |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 31 | #include <linux/idr.h> |
Al Viro | 5ad4e53 | 2009-03-29 19:50:06 -0400 | [diff] [blame] | 32 | #include <linux/fs_struct.h> |
Andreas Gruenbacher | 2504c5d | 2009-12-17 21:24:27 -0500 | [diff] [blame] | 33 | #include <linux/fsnotify.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | #include <asm/uaccess.h> |
| 35 | #include <asm/unistd.h> |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 36 | #include "pnode.h" |
Adrian Bunk | 948730b | 2007-07-15 23:41:25 -0700 | [diff] [blame] | 37 | #include "internal.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 39 | #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) |
| 40 | #define HASH_SIZE (1UL << HASH_SHIFT) |
| 41 | |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 42 | static int event; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 43 | static DEFINE_IDA(mnt_id_ida); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 44 | static DEFINE_IDA(mnt_group_ida); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 45 | static DEFINE_SPINLOCK(mnt_id_lock); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 46 | static int mnt_id_start = 0; |
| 47 | static int mnt_group_start = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 49 | static struct list_head *mount_hashtable __read_mostly; |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 50 | static struct kmem_cache *mnt_cache __read_mostly; |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 51 | static struct rw_semaphore namespace_sem; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 53 | /* /sys/fs */ |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 54 | struct kobject *fs_kobj; |
| 55 | EXPORT_SYMBOL_GPL(fs_kobj); |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 56 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 57 | /* |
| 58 | * vfsmount lock may be taken for read to prevent changes to the |
| 59 | * vfsmount hash, ie. during mountpoint lookups or walking back |
| 60 | * up the tree. |
| 61 | * |
| 62 | * It should be taken for write in all cases where the vfsmount |
| 63 | * tree or hash is modified or when a vfsmount structure is modified. |
| 64 | */ |
| 65 | DEFINE_BRLOCK(vfsmount_lock); |
| 66 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
| 68 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 69 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 70 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 71 | tmp = tmp + (tmp >> HASH_SHIFT); |
| 72 | return tmp & (HASH_SIZE - 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 73 | } |
| 74 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 75 | #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) |
| 76 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 77 | /* |
| 78 | * allocation is serialized by namespace_sem, but we need the spinlock to |
| 79 | * serialize with freeing. |
| 80 | */ |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 81 | static int mnt_alloc_id(struct vfsmount *mnt) |
| 82 | { |
| 83 | int res; |
| 84 | |
| 85 | retry: |
| 86 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 87 | spin_lock(&mnt_id_lock); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 88 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); |
| 89 | if (!res) |
| 90 | mnt_id_start = mnt->mnt_id + 1; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 91 | spin_unlock(&mnt_id_lock); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 92 | if (res == -EAGAIN) |
| 93 | goto retry; |
| 94 | |
| 95 | return res; |
| 96 | } |
| 97 | |
| 98 | static void mnt_free_id(struct vfsmount *mnt) |
| 99 | { |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 100 | int id = mnt->mnt_id; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 101 | spin_lock(&mnt_id_lock); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 102 | ida_remove(&mnt_id_ida, id); |
| 103 | if (mnt_id_start > id) |
| 104 | mnt_id_start = id; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 105 | spin_unlock(&mnt_id_lock); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 106 | } |
| 107 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 108 | /* |
| 109 | * Allocate a new peer group ID |
| 110 | * |
| 111 | * mnt_group_ida is protected by namespace_sem |
| 112 | */ |
| 113 | static int mnt_alloc_group_id(struct vfsmount *mnt) |
| 114 | { |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 115 | int res; |
| 116 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 117 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
| 118 | return -ENOMEM; |
| 119 | |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 120 | res = ida_get_new_above(&mnt_group_ida, |
| 121 | mnt_group_start, |
| 122 | &mnt->mnt_group_id); |
| 123 | if (!res) |
| 124 | mnt_group_start = mnt->mnt_group_id + 1; |
| 125 | |
| 126 | return res; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 127 | } |
| 128 | |
| 129 | /* |
| 130 | * Release a peer group ID |
| 131 | */ |
| 132 | void mnt_release_group_id(struct vfsmount *mnt) |
| 133 | { |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 134 | int id = mnt->mnt_group_id; |
| 135 | ida_remove(&mnt_group_ida, id); |
| 136 | if (mnt_group_start > id) |
| 137 | mnt_group_start = id; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 138 | mnt->mnt_group_id = 0; |
| 139 | } |
| 140 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 141 | /* |
| 142 | * vfsmount lock must be held for read |
| 143 | */ |
| 144 | static inline void mnt_add_count(struct vfsmount *mnt, int n) |
| 145 | { |
| 146 | #ifdef CONFIG_SMP |
| 147 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
| 148 | #else |
| 149 | preempt_disable(); |
| 150 | mnt->mnt_count += n; |
| 151 | preempt_enable(); |
| 152 | #endif |
| 153 | } |
| 154 | |
| 155 | static inline void mnt_set_count(struct vfsmount *mnt, int n) |
| 156 | { |
| 157 | #ifdef CONFIG_SMP |
| 158 | this_cpu_write(mnt->mnt_pcp->mnt_count, n); |
| 159 | #else |
| 160 | mnt->mnt_count = n; |
| 161 | #endif |
| 162 | } |
| 163 | |
| 164 | /* |
| 165 | * vfsmount lock must be held for read |
| 166 | */ |
| 167 | static inline void mnt_inc_count(struct vfsmount *mnt) |
| 168 | { |
| 169 | mnt_add_count(mnt, 1); |
| 170 | } |
| 171 | |
| 172 | /* |
| 173 | * vfsmount lock must be held for read |
| 174 | */ |
| 175 | static inline void mnt_dec_count(struct vfsmount *mnt) |
| 176 | { |
| 177 | mnt_add_count(mnt, -1); |
| 178 | } |
| 179 | |
| 180 | /* |
| 181 | * vfsmount lock must be held for write |
| 182 | */ |
| 183 | unsigned int mnt_get_count(struct vfsmount *mnt) |
| 184 | { |
| 185 | #ifdef CONFIG_SMP |
| 186 | unsigned int count = atomic_read(&mnt->mnt_longrefs); |
| 187 | int cpu; |
| 188 | |
| 189 | for_each_possible_cpu(cpu) { |
| 190 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
| 191 | } |
| 192 | |
| 193 | return count; |
| 194 | #else |
| 195 | return mnt->mnt_count; |
| 196 | #endif |
| 197 | } |
| 198 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 199 | struct vfsmount *alloc_vfsmnt(const char *name) |
| 200 | { |
Robert P. J. Day | c376222 | 2007-02-10 01:45:03 -0800 | [diff] [blame] | 201 | struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 202 | if (mnt) { |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 203 | int err; |
| 204 | |
| 205 | err = mnt_alloc_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 206 | if (err) |
| 207 | goto out_free_cache; |
| 208 | |
| 209 | if (name) { |
| 210 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); |
| 211 | if (!mnt->mnt_devname) |
| 212 | goto out_free_id; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 213 | } |
| 214 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 215 | #ifdef CONFIG_SMP |
| 216 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
| 217 | if (!mnt->mnt_pcp) |
| 218 | goto out_free_devname; |
| 219 | |
| 220 | atomic_set(&mnt->mnt_longrefs, 1); |
| 221 | #else |
| 222 | mnt->mnt_count = 1; |
| 223 | mnt->mnt_writers = 0; |
| 224 | #endif |
| 225 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | INIT_LIST_HEAD(&mnt->mnt_hash); |
| 227 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 228 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 229 | INIT_LIST_HEAD(&mnt->mnt_list); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 230 | INIT_LIST_HEAD(&mnt->mnt_expire); |
Ram Pai | 03e06e6 | 2005-11-07 17:19:33 -0500 | [diff] [blame] | 231 | INIT_LIST_HEAD(&mnt->mnt_share); |
Ram Pai | a58b0eb | 2005-11-07 17:20:48 -0500 | [diff] [blame] | 232 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 233 | INIT_LIST_HEAD(&mnt->mnt_slave); |
Andreas Gruenbacher | 2504c5d | 2009-12-17 21:24:27 -0500 | [diff] [blame] | 234 | #ifdef CONFIG_FSNOTIFY |
| 235 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); |
| 236 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 237 | } |
| 238 | return mnt; |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 239 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 240 | #ifdef CONFIG_SMP |
| 241 | out_free_devname: |
| 242 | kfree(mnt->mnt_devname); |
| 243 | #endif |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 244 | out_free_id: |
| 245 | mnt_free_id(mnt); |
| 246 | out_free_cache: |
| 247 | kmem_cache_free(mnt_cache, mnt); |
| 248 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 249 | } |
| 250 | |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 251 | /* |
| 252 | * Most r/o checks on a fs are for operations that take |
| 253 | * discrete amounts of time, like a write() or unlink(). |
| 254 | * We must keep track of when those operations start |
| 255 | * (for permission checks) and when they end, so that |
| 256 | * we can determine when writes are able to occur to |
| 257 | * a filesystem. |
| 258 | */ |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 259 | /* |
| 260 | * __mnt_is_readonly: check whether a mount is read-only |
| 261 | * @mnt: the mount to check for its write status |
| 262 | * |
| 263 | * This shouldn't be used directly ouside of the VFS. |
| 264 | * It does not guarantee that the filesystem will stay |
| 265 | * r/w, just that it is right *now*. This can not and |
| 266 | * should not be used in place of IS_RDONLY(inode). |
| 267 | * mnt_want/drop_write() will _keep_ the filesystem |
| 268 | * r/w. |
| 269 | */ |
| 270 | int __mnt_is_readonly(struct vfsmount *mnt) |
| 271 | { |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 272 | if (mnt->mnt_flags & MNT_READONLY) |
| 273 | return 1; |
| 274 | if (mnt->mnt_sb->s_flags & MS_RDONLY) |
| 275 | return 1; |
| 276 | return 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 277 | } |
| 278 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); |
| 279 | |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 280 | static inline void mnt_inc_writers(struct vfsmount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 281 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 282 | #ifdef CONFIG_SMP |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 283 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 284 | #else |
| 285 | mnt->mnt_writers++; |
| 286 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 287 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 288 | |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 289 | static inline void mnt_dec_writers(struct vfsmount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 290 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 291 | #ifdef CONFIG_SMP |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 292 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 293 | #else |
| 294 | mnt->mnt_writers--; |
| 295 | #endif |
| 296 | } |
| 297 | |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 298 | static unsigned int mnt_get_writers(struct vfsmount *mnt) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 299 | { |
| 300 | #ifdef CONFIG_SMP |
| 301 | unsigned int count = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 302 | int cpu; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 303 | |
| 304 | for_each_possible_cpu(cpu) { |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 305 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 306 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 307 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 308 | return count; |
| 309 | #else |
| 310 | return mnt->mnt_writers; |
| 311 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 312 | } |
| 313 | |
| 314 | /* |
| 315 | * Most r/o checks on a fs are for operations that take |
| 316 | * discrete amounts of time, like a write() or unlink(). |
| 317 | * We must keep track of when those operations start |
| 318 | * (for permission checks) and when they end, so that |
| 319 | * we can determine when writes are able to occur to |
| 320 | * a filesystem. |
| 321 | */ |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 322 | /** |
| 323 | * mnt_want_write - get write access to a mount |
| 324 | * @mnt: the mount on which to take a write |
| 325 | * |
| 326 | * This tells the low-level filesystem that a write is |
| 327 | * about to be performed to it, and makes sure that |
| 328 | * writes are allowed before returning success. When |
| 329 | * the write operation is finished, mnt_drop_write() |
| 330 | * must be called. This is effectively a refcount. |
| 331 | */ |
| 332 | int mnt_want_write(struct vfsmount *mnt) |
| 333 | { |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 334 | int ret = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 335 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 336 | preempt_disable(); |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 337 | mnt_inc_writers(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 338 | /* |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 339 | * The store to mnt_inc_writers must be visible before we pass |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 340 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
| 341 | * incremented count after it has set MNT_WRITE_HOLD. |
| 342 | */ |
| 343 | smp_mb(); |
| 344 | while (mnt->mnt_flags & MNT_WRITE_HOLD) |
| 345 | cpu_relax(); |
| 346 | /* |
| 347 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will |
| 348 | * be set to match its requirements. So we must not load that until |
| 349 | * MNT_WRITE_HOLD is cleared. |
| 350 | */ |
| 351 | smp_rmb(); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 352 | if (__mnt_is_readonly(mnt)) { |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 353 | mnt_dec_writers(mnt); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 354 | ret = -EROFS; |
| 355 | goto out; |
| 356 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 357 | out: |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 358 | preempt_enable(); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 359 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 360 | } |
| 361 | EXPORT_SYMBOL_GPL(mnt_want_write); |
| 362 | |
| 363 | /** |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 364 | * mnt_clone_write - get write access to a mount |
| 365 | * @mnt: the mount on which to take a write |
| 366 | * |
| 367 | * This is effectively like mnt_want_write, except |
| 368 | * it must only be used to take an extra write reference |
| 369 | * on a mountpoint that we already know has a write reference |
| 370 | * on it. This allows some optimisation. |
| 371 | * |
| 372 | * After finished, mnt_drop_write must be called as usual to |
| 373 | * drop the reference. |
| 374 | */ |
| 375 | int mnt_clone_write(struct vfsmount *mnt) |
| 376 | { |
| 377 | /* superblock may be r/o */ |
| 378 | if (__mnt_is_readonly(mnt)) |
| 379 | return -EROFS; |
| 380 | preempt_disable(); |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 381 | mnt_inc_writers(mnt); |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 382 | preempt_enable(); |
| 383 | return 0; |
| 384 | } |
| 385 | EXPORT_SYMBOL_GPL(mnt_clone_write); |
| 386 | |
| 387 | /** |
| 388 | * mnt_want_write_file - get write access to a file's mount |
| 389 | * @file: the file who's mount on which to take a write |
| 390 | * |
| 391 | * This is like mnt_want_write, but it takes a file and can |
| 392 | * do some optimisations if the file is open for write already |
| 393 | */ |
| 394 | int mnt_want_write_file(struct file *file) |
| 395 | { |
OGAWA Hirofumi | 2d8dd38 | 2009-08-06 15:07:39 -0700 | [diff] [blame] | 396 | struct inode *inode = file->f_dentry->d_inode; |
| 397 | if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 398 | return mnt_want_write(file->f_path.mnt); |
| 399 | else |
| 400 | return mnt_clone_write(file->f_path.mnt); |
| 401 | } |
| 402 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
| 403 | |
| 404 | /** |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 405 | * mnt_drop_write - give up write access to a mount |
| 406 | * @mnt: the mount on which to give up write access |
| 407 | * |
| 408 | * Tells the low-level filesystem that we are done |
| 409 | * performing writes to it. Must be matched with |
| 410 | * mnt_want_write() call above. |
| 411 | */ |
| 412 | void mnt_drop_write(struct vfsmount *mnt) |
| 413 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 414 | preempt_disable(); |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 415 | mnt_dec_writers(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 416 | preempt_enable(); |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 417 | } |
| 418 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
| 419 | |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 420 | static int mnt_make_readonly(struct vfsmount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 421 | { |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 422 | int ret = 0; |
| 423 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 424 | br_write_lock(vfsmount_lock); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 425 | mnt->mnt_flags |= MNT_WRITE_HOLD; |
| 426 | /* |
| 427 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
| 428 | * should be visible before we do. |
| 429 | */ |
| 430 | smp_mb(); |
| 431 | |
| 432 | /* |
| 433 | * With writers on hold, if this value is zero, then there are |
| 434 | * definitely no active writers (although held writers may subsequently |
| 435 | * increment the count, they'll have to wait, and decrement it after |
| 436 | * seeing MNT_READONLY). |
| 437 | * |
| 438 | * It is OK to have counter incremented on one CPU and decremented on |
| 439 | * another: the sum will add up correctly. The danger would be when we |
| 440 | * sum up each counter, if we read a counter before it is incremented, |
| 441 | * but then read another CPU's count which it has been subsequently |
| 442 | * decremented from -- we would see more decrements than we should. |
| 443 | * MNT_WRITE_HOLD protects against this scenario, because |
| 444 | * mnt_want_write first increments count, then smp_mb, then spins on |
| 445 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while |
| 446 | * we're counting up here. |
| 447 | */ |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 448 | if (mnt_get_writers(mnt) > 0) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 449 | ret = -EBUSY; |
| 450 | else |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 451 | mnt->mnt_flags |= MNT_READONLY; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 452 | /* |
| 453 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers |
| 454 | * that become unheld will see MNT_READONLY. |
| 455 | */ |
| 456 | smp_wmb(); |
| 457 | mnt->mnt_flags &= ~MNT_WRITE_HOLD; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 458 | br_write_unlock(vfsmount_lock); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 459 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 460 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 461 | |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 462 | static void __mnt_unmake_readonly(struct vfsmount *mnt) |
| 463 | { |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 464 | br_write_lock(vfsmount_lock); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 465 | mnt->mnt_flags &= ~MNT_READONLY; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 466 | br_write_unlock(vfsmount_lock); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 467 | } |
| 468 | |
Sukadev Bhattiprolu | a3ec947 | 2009-03-04 12:06:34 -0800 | [diff] [blame] | 469 | void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) |
David Howells | 454e239 | 2006-06-23 02:02:57 -0700 | [diff] [blame] | 470 | { |
| 471 | mnt->mnt_sb = sb; |
| 472 | mnt->mnt_root = dget(sb->s_root); |
David Howells | 454e239 | 2006-06-23 02:02:57 -0700 | [diff] [blame] | 473 | } |
| 474 | |
| 475 | EXPORT_SYMBOL(simple_set_mnt); |
| 476 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 477 | void free_vfsmnt(struct vfsmount *mnt) |
| 478 | { |
| 479 | kfree(mnt->mnt_devname); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 480 | mnt_free_id(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 481 | #ifdef CONFIG_SMP |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 482 | free_percpu(mnt->mnt_pcp); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 483 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 484 | kmem_cache_free(mnt_cache, mnt); |
| 485 | } |
| 486 | |
| 487 | /* |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 488 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
| 489 | * @dir. If @dir is set return the first mount else return the last mount. |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 490 | * vfsmount_lock must be held for read or write. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 491 | */ |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 492 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
| 493 | int dir) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 494 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 495 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
| 496 | struct list_head *tmp = head; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 497 | struct vfsmount *p, *found = NULL; |
| 498 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 499 | for (;;) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 500 | tmp = dir ? tmp->next : tmp->prev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 501 | p = NULL; |
| 502 | if (tmp == head) |
| 503 | break; |
| 504 | p = list_entry(tmp, struct vfsmount, mnt_hash); |
| 505 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 506 | found = p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | break; |
| 508 | } |
| 509 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 510 | return found; |
| 511 | } |
| 512 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 513 | /* |
| 514 | * lookup_mnt increments the ref count before returning |
| 515 | * the vfsmount struct. |
| 516 | */ |
Al Viro | 1c755af | 2009-04-18 14:06:57 -0400 | [diff] [blame] | 517 | struct vfsmount *lookup_mnt(struct path *path) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 518 | { |
| 519 | struct vfsmount *child_mnt; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 520 | |
| 521 | br_read_lock(vfsmount_lock); |
Al Viro | 1c755af | 2009-04-18 14:06:57 -0400 | [diff] [blame] | 522 | if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1))) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 523 | mntget(child_mnt); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 524 | br_read_unlock(vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 525 | return child_mnt; |
| 526 | } |
| 527 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 528 | static inline int check_mnt(struct vfsmount *mnt) |
| 529 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 530 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 531 | } |
| 532 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 533 | /* |
| 534 | * vfsmount lock must be held for write |
| 535 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 536 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 537 | { |
| 538 | if (ns) { |
| 539 | ns->event = ++event; |
| 540 | wake_up_interruptible(&ns->poll); |
| 541 | } |
| 542 | } |
| 543 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 544 | /* |
| 545 | * vfsmount lock must be held for write |
| 546 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 547 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 548 | { |
| 549 | if (ns && ns->event != event) { |
| 550 | ns->event = event; |
| 551 | wake_up_interruptible(&ns->poll); |
| 552 | } |
| 553 | } |
| 554 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 555 | /* |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 556 | * Clear dentry's mounted state if it has no remaining mounts. |
| 557 | * vfsmount_lock must be held for write. |
| 558 | */ |
| 559 | static void dentry_reset_mounted(struct vfsmount *mnt, struct dentry *dentry) |
| 560 | { |
| 561 | unsigned u; |
| 562 | |
| 563 | for (u = 0; u < HASH_SIZE; u++) { |
| 564 | struct vfsmount *p; |
| 565 | |
| 566 | list_for_each_entry(p, &mount_hashtable[u], mnt_hash) { |
| 567 | if (p->mnt_mountpoint == dentry) |
| 568 | return; |
| 569 | } |
| 570 | } |
| 571 | spin_lock(&dentry->d_lock); |
| 572 | dentry->d_flags &= ~DCACHE_MOUNTED; |
| 573 | spin_unlock(&dentry->d_lock); |
| 574 | } |
| 575 | |
| 576 | /* |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 577 | * vfsmount lock must be held for write |
| 578 | */ |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 579 | static void detach_mnt(struct vfsmount *mnt, struct path *old_path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 580 | { |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 581 | old_path->dentry = mnt->mnt_mountpoint; |
| 582 | old_path->mnt = mnt->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 583 | mnt->mnt_parent = mnt; |
| 584 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 585 | list_del_init(&mnt->mnt_child); |
| 586 | list_del_init(&mnt->mnt_hash); |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 587 | dentry_reset_mounted(old_path->mnt, old_path->dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 588 | } |
| 589 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 590 | /* |
| 591 | * vfsmount lock must be held for write |
| 592 | */ |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 593 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
| 594 | struct vfsmount *child_mnt) |
| 595 | { |
| 596 | child_mnt->mnt_parent = mntget(mnt); |
| 597 | child_mnt->mnt_mountpoint = dget(dentry); |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 598 | spin_lock(&dentry->d_lock); |
| 599 | dentry->d_flags |= DCACHE_MOUNTED; |
| 600 | spin_unlock(&dentry->d_lock); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 601 | } |
| 602 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 603 | /* |
| 604 | * vfsmount lock must be held for write |
| 605 | */ |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 606 | static void attach_mnt(struct vfsmount *mnt, struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 607 | { |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 608 | mnt_set_mountpoint(path->mnt, path->dentry, mnt); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 609 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 610 | hash(path->mnt, path->dentry)); |
| 611 | list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 612 | } |
| 613 | |
| 614 | /* |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 615 | * vfsmount lock must be held for write |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 616 | */ |
| 617 | static void commit_tree(struct vfsmount *mnt) |
| 618 | { |
| 619 | struct vfsmount *parent = mnt->mnt_parent; |
| 620 | struct vfsmount *m; |
| 621 | LIST_HEAD(head); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 622 | struct mnt_namespace *n = parent->mnt_ns; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 623 | |
| 624 | BUG_ON(parent == mnt); |
| 625 | |
| 626 | list_add_tail(&head, &mnt->mnt_list); |
| 627 | list_for_each_entry(m, &head, mnt_list) |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 628 | m->mnt_ns = n; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 629 | list_splice(&head, n->list.prev); |
| 630 | |
| 631 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
| 632 | hash(parent, mnt->mnt_mountpoint)); |
| 633 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 634 | touch_mnt_namespace(n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 635 | } |
| 636 | |
| 637 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) |
| 638 | { |
| 639 | struct list_head *next = p->mnt_mounts.next; |
| 640 | if (next == &p->mnt_mounts) { |
| 641 | while (1) { |
| 642 | if (p == root) |
| 643 | return NULL; |
| 644 | next = p->mnt_child.next; |
| 645 | if (next != &p->mnt_parent->mnt_mounts) |
| 646 | break; |
| 647 | p = p->mnt_parent; |
| 648 | } |
| 649 | } |
| 650 | return list_entry(next, struct vfsmount, mnt_child); |
| 651 | } |
| 652 | |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 653 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
| 654 | { |
| 655 | struct list_head *prev = p->mnt_mounts.prev; |
| 656 | while (prev != &p->mnt_mounts) { |
| 657 | p = list_entry(prev, struct vfsmount, mnt_child); |
| 658 | prev = p->mnt_mounts.prev; |
| 659 | } |
| 660 | return p; |
| 661 | } |
| 662 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 663 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
| 664 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 665 | { |
| 666 | struct super_block *sb = old->mnt_sb; |
| 667 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); |
| 668 | |
| 669 | if (mnt) { |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 670 | if (flag & (CL_SLAVE | CL_PRIVATE)) |
| 671 | mnt->mnt_group_id = 0; /* not a peer of original */ |
| 672 | else |
| 673 | mnt->mnt_group_id = old->mnt_group_id; |
| 674 | |
| 675 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
| 676 | int err = mnt_alloc_group_id(mnt); |
| 677 | if (err) |
| 678 | goto out_free; |
| 679 | } |
| 680 | |
Miklos Szeredi | be1a16a | 2010-10-05 12:31:09 +0200 | [diff] [blame] | 681 | mnt->mnt_flags = old->mnt_flags & ~MNT_WRITE_HOLD; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 682 | atomic_inc(&sb->s_active); |
| 683 | mnt->mnt_sb = sb; |
| 684 | mnt->mnt_root = dget(root); |
| 685 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 686 | mnt->mnt_parent = mnt; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 687 | |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 688 | if (flag & CL_SLAVE) { |
| 689 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
| 690 | mnt->mnt_master = old; |
| 691 | CLEAR_MNT_SHARED(mnt); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 692 | } else if (!(flag & CL_PRIVATE)) { |
Al Viro | 796a6b5 | 2010-01-16 13:28:47 -0500 | [diff] [blame] | 693 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 694 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 695 | if (IS_MNT_SLAVE(old)) |
| 696 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
| 697 | mnt->mnt_master = old->mnt_master; |
| 698 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 699 | if (flag & CL_MAKE_SHARED) |
| 700 | set_mnt_shared(mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 701 | |
| 702 | /* stick the duplicate mount on the same expiry list |
| 703 | * as the original if that was on one */ |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 704 | if (flag & CL_EXPIRE) { |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 705 | if (!list_empty(&old->mnt_expire)) |
| 706 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 707 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 708 | } |
| 709 | return mnt; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 710 | |
| 711 | out_free: |
| 712 | free_vfsmnt(mnt); |
| 713 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 714 | } |
| 715 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 716 | static inline void mntfree(struct vfsmount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 717 | { |
| 718 | struct super_block *sb = mnt->mnt_sb; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 719 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 720 | /* |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 721 | * This probably indicates that somebody messed |
| 722 | * up a mnt_want/drop_write() pair. If this |
| 723 | * happens, the filesystem was probably unable |
| 724 | * to make r/w->r/o transitions. |
| 725 | */ |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 726 | /* |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 727 | * The locking used to deal with mnt_count decrement provides barriers, |
| 728 | * so mnt_get_writers() below is safe. |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 729 | */ |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 730 | WARN_ON(mnt_get_writers(mnt)); |
Andreas Gruenbacher | ca9c726 | 2009-12-17 21:24:27 -0500 | [diff] [blame] | 731 | fsnotify_vfsmount_delete(mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 732 | dput(mnt->mnt_root); |
| 733 | free_vfsmnt(mnt); |
| 734 | deactivate_super(sb); |
| 735 | } |
| 736 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 737 | #ifdef CONFIG_SMP |
| 738 | static inline void __mntput(struct vfsmount *mnt, int longrefs) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 739 | { |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 740 | if (!longrefs) { |
| 741 | put_again: |
| 742 | br_read_lock(vfsmount_lock); |
| 743 | if (likely(atomic_read(&mnt->mnt_longrefs))) { |
| 744 | mnt_dec_count(mnt); |
| 745 | br_read_unlock(vfsmount_lock); |
| 746 | return; |
| 747 | } |
| 748 | br_read_unlock(vfsmount_lock); |
| 749 | } else { |
| 750 | BUG_ON(!atomic_read(&mnt->mnt_longrefs)); |
| 751 | if (atomic_add_unless(&mnt->mnt_longrefs, -1, 1)) |
| 752 | return; |
| 753 | } |
| 754 | |
| 755 | br_write_lock(vfsmount_lock); |
| 756 | if (!longrefs) |
| 757 | mnt_dec_count(mnt); |
| 758 | else |
| 759 | atomic_dec(&mnt->mnt_longrefs); |
| 760 | if (mnt_get_count(mnt)) { |
| 761 | br_write_unlock(vfsmount_lock); |
| 762 | return; |
| 763 | } |
| 764 | if (unlikely(mnt->mnt_pinned)) { |
| 765 | mnt_add_count(mnt, mnt->mnt_pinned + 1); |
| 766 | mnt->mnt_pinned = 0; |
| 767 | br_write_unlock(vfsmount_lock); |
| 768 | acct_auto_close_mnt(mnt); |
| 769 | goto put_again; |
| 770 | } |
| 771 | br_write_unlock(vfsmount_lock); |
| 772 | mntfree(mnt); |
| 773 | } |
| 774 | #else |
| 775 | static inline void __mntput(struct vfsmount *mnt, int longrefs) |
| 776 | { |
| 777 | put_again: |
| 778 | mnt_dec_count(mnt); |
| 779 | if (likely(mnt_get_count(mnt))) |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 780 | return; |
| 781 | br_write_lock(vfsmount_lock); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 782 | if (unlikely(mnt->mnt_pinned)) { |
| 783 | mnt_add_count(mnt, mnt->mnt_pinned + 1); |
| 784 | mnt->mnt_pinned = 0; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 785 | br_write_unlock(vfsmount_lock); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 786 | acct_auto_close_mnt(mnt); |
| 787 | goto put_again; |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 788 | } |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 789 | br_write_unlock(vfsmount_lock); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 790 | mntfree(mnt); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 791 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 792 | #endif |
| 793 | |
| 794 | static void mntput_no_expire(struct vfsmount *mnt) |
| 795 | { |
| 796 | __mntput(mnt, 0); |
| 797 | } |
| 798 | |
| 799 | void mntput(struct vfsmount *mnt) |
| 800 | { |
| 801 | if (mnt) { |
| 802 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
| 803 | if (unlikely(mnt->mnt_expiry_mark)) |
| 804 | mnt->mnt_expiry_mark = 0; |
| 805 | __mntput(mnt, 0); |
| 806 | } |
| 807 | } |
| 808 | EXPORT_SYMBOL(mntput); |
| 809 | |
| 810 | struct vfsmount *mntget(struct vfsmount *mnt) |
| 811 | { |
| 812 | if (mnt) |
| 813 | mnt_inc_count(mnt); |
| 814 | return mnt; |
| 815 | } |
| 816 | EXPORT_SYMBOL(mntget); |
| 817 | |
| 818 | void mntput_long(struct vfsmount *mnt) |
| 819 | { |
| 820 | #ifdef CONFIG_SMP |
| 821 | if (mnt) { |
| 822 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
| 823 | if (unlikely(mnt->mnt_expiry_mark)) |
| 824 | mnt->mnt_expiry_mark = 0; |
| 825 | __mntput(mnt, 1); |
| 826 | } |
| 827 | #else |
| 828 | mntput(mnt); |
| 829 | #endif |
| 830 | } |
| 831 | EXPORT_SYMBOL(mntput_long); |
| 832 | |
| 833 | struct vfsmount *mntget_long(struct vfsmount *mnt) |
| 834 | { |
| 835 | #ifdef CONFIG_SMP |
| 836 | if (mnt) |
| 837 | atomic_inc(&mnt->mnt_longrefs); |
| 838 | return mnt; |
| 839 | #else |
| 840 | return mntget(mnt); |
| 841 | #endif |
| 842 | } |
| 843 | EXPORT_SYMBOL(mntget_long); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 844 | |
| 845 | void mnt_pin(struct vfsmount *mnt) |
| 846 | { |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 847 | br_write_lock(vfsmount_lock); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 848 | mnt->mnt_pinned++; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 849 | br_write_unlock(vfsmount_lock); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 850 | } |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 851 | EXPORT_SYMBOL(mnt_pin); |
| 852 | |
| 853 | void mnt_unpin(struct vfsmount *mnt) |
| 854 | { |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 855 | br_write_lock(vfsmount_lock); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 856 | if (mnt->mnt_pinned) { |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 857 | mnt_inc_count(mnt); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 858 | mnt->mnt_pinned--; |
| 859 | } |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 860 | br_write_unlock(vfsmount_lock); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 861 | } |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 862 | EXPORT_SYMBOL(mnt_unpin); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 863 | |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 864 | static inline void mangle(struct seq_file *m, const char *s) |
| 865 | { |
| 866 | seq_escape(m, s, " \t\n\\"); |
| 867 | } |
| 868 | |
| 869 | /* |
| 870 | * Simple .show_options callback for filesystems which don't want to |
| 871 | * implement more complex mount option showing. |
| 872 | * |
| 873 | * See also save_mount_options(). |
| 874 | */ |
| 875 | int generic_show_options(struct seq_file *m, struct vfsmount *mnt) |
| 876 | { |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 877 | const char *options; |
| 878 | |
| 879 | rcu_read_lock(); |
| 880 | options = rcu_dereference(mnt->mnt_sb->s_options); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 881 | |
| 882 | if (options != NULL && options[0]) { |
| 883 | seq_putc(m, ','); |
| 884 | mangle(m, options); |
| 885 | } |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 886 | rcu_read_unlock(); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 887 | |
| 888 | return 0; |
| 889 | } |
| 890 | EXPORT_SYMBOL(generic_show_options); |
| 891 | |
| 892 | /* |
| 893 | * If filesystem uses generic_show_options(), this function should be |
| 894 | * called from the fill_super() callback. |
| 895 | * |
| 896 | * The .remount_fs callback usually needs to be handled in a special |
| 897 | * way, to make sure, that previous options are not overwritten if the |
| 898 | * remount fails. |
| 899 | * |
| 900 | * Also note, that if the filesystem's .remount_fs function doesn't |
| 901 | * reset all options to their default value, but changes only newly |
| 902 | * given options, then the displayed options will not reflect reality |
| 903 | * any more. |
| 904 | */ |
| 905 | void save_mount_options(struct super_block *sb, char *options) |
| 906 | { |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 907 | BUG_ON(sb->s_options); |
| 908 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 909 | } |
| 910 | EXPORT_SYMBOL(save_mount_options); |
| 911 | |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 912 | void replace_mount_options(struct super_block *sb, char *options) |
| 913 | { |
| 914 | char *old = sb->s_options; |
| 915 | rcu_assign_pointer(sb->s_options, options); |
| 916 | if (old) { |
| 917 | synchronize_rcu(); |
| 918 | kfree(old); |
| 919 | } |
| 920 | } |
| 921 | EXPORT_SYMBOL(replace_mount_options); |
| 922 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 923 | #ifdef CONFIG_PROC_FS |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 924 | /* iterator */ |
| 925 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 926 | { |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 927 | struct proc_mounts *p = m->private; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 928 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 929 | down_read(&namespace_sem); |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 930 | return seq_list_start(&p->ns->list, *pos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 931 | } |
| 932 | |
| 933 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 934 | { |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 935 | struct proc_mounts *p = m->private; |
Pavel Emelianov | b0765fb | 2007-07-15 23:39:55 -0700 | [diff] [blame] | 936 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 937 | return seq_list_next(v, &p->ns->list, pos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 938 | } |
| 939 | |
| 940 | static void m_stop(struct seq_file *m, void *v) |
| 941 | { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 942 | up_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 943 | } |
| 944 | |
Al Viro | 9f5596a | 2010-02-05 00:40:25 -0500 | [diff] [blame] | 945 | int mnt_had_events(struct proc_mounts *p) |
| 946 | { |
| 947 | struct mnt_namespace *ns = p->ns; |
| 948 | int res = 0; |
| 949 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 950 | br_read_lock(vfsmount_lock); |
Al Viro | 9f5596a | 2010-02-05 00:40:25 -0500 | [diff] [blame] | 951 | if (p->event != ns->event) { |
| 952 | p->event = ns->event; |
| 953 | res = 1; |
| 954 | } |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 955 | br_read_unlock(vfsmount_lock); |
Al Viro | 9f5596a | 2010-02-05 00:40:25 -0500 | [diff] [blame] | 956 | |
| 957 | return res; |
| 958 | } |
| 959 | |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 960 | struct proc_fs_info { |
| 961 | int flag; |
| 962 | const char *str; |
| 963 | }; |
| 964 | |
Eric Paris | 2069f45 | 2008-07-04 09:47:13 +1000 | [diff] [blame] | 965 | static int show_sb_opts(struct seq_file *m, struct super_block *sb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 966 | { |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 967 | static const struct proc_fs_info fs_info[] = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 968 | { MS_SYNCHRONOUS, ",sync" }, |
| 969 | { MS_DIRSYNC, ",dirsync" }, |
| 970 | { MS_MANDLOCK, ",mand" }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 971 | { 0, NULL } |
| 972 | }; |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 973 | const struct proc_fs_info *fs_infop; |
| 974 | |
| 975 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { |
| 976 | if (sb->s_flags & fs_infop->flag) |
| 977 | seq_puts(m, fs_infop->str); |
| 978 | } |
Eric Paris | 2069f45 | 2008-07-04 09:47:13 +1000 | [diff] [blame] | 979 | |
| 980 | return security_sb_show_options(m, sb); |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 981 | } |
| 982 | |
| 983 | static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) |
| 984 | { |
| 985 | static const struct proc_fs_info mnt_info[] = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 986 | { MNT_NOSUID, ",nosuid" }, |
| 987 | { MNT_NODEV, ",nodev" }, |
| 988 | { MNT_NOEXEC, ",noexec" }, |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 989 | { MNT_NOATIME, ",noatime" }, |
| 990 | { MNT_NODIRATIME, ",nodiratime" }, |
Valerie Henson | 47ae32d | 2006-12-13 00:34:34 -0800 | [diff] [blame] | 991 | { MNT_RELATIME, ",relatime" }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 992 | { 0, NULL } |
| 993 | }; |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 994 | const struct proc_fs_info *fs_infop; |
| 995 | |
| 996 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { |
| 997 | if (mnt->mnt_flags & fs_infop->flag) |
| 998 | seq_puts(m, fs_infop->str); |
| 999 | } |
| 1000 | } |
| 1001 | |
| 1002 | static void show_type(struct seq_file *m, struct super_block *sb) |
| 1003 | { |
| 1004 | mangle(m, sb->s_type->name); |
| 1005 | if (sb->s_subtype && sb->s_subtype[0]) { |
| 1006 | seq_putc(m, '.'); |
| 1007 | mangle(m, sb->s_subtype); |
| 1008 | } |
| 1009 | } |
| 1010 | |
| 1011 | static int show_vfsmnt(struct seq_file *m, void *v) |
| 1012 | { |
| 1013 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
| 1014 | int err = 0; |
Jan Blunck | c32c2f6 | 2008-02-14 19:38:43 -0800 | [diff] [blame] | 1015 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1016 | |
| 1017 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); |
| 1018 | seq_putc(m, ' '); |
Jan Blunck | c32c2f6 | 2008-02-14 19:38:43 -0800 | [diff] [blame] | 1019 | seq_path(m, &mnt_path, " \t\n\\"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1020 | seq_putc(m, ' '); |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 1021 | show_type(m, mnt->mnt_sb); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1022 | seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); |
Eric Paris | 2069f45 | 2008-07-04 09:47:13 +1000 | [diff] [blame] | 1023 | err = show_sb_opts(m, mnt->mnt_sb); |
| 1024 | if (err) |
| 1025 | goto out; |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 1026 | show_mnt_opts(m, mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1027 | if (mnt->mnt_sb->s_op->show_options) |
| 1028 | err = mnt->mnt_sb->s_op->show_options(m, mnt); |
| 1029 | seq_puts(m, " 0 0\n"); |
Eric Paris | 2069f45 | 2008-07-04 09:47:13 +1000 | [diff] [blame] | 1030 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1031 | return err; |
| 1032 | } |
| 1033 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1034 | const struct seq_operations mounts_op = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1035 | .start = m_start, |
| 1036 | .next = m_next, |
| 1037 | .stop = m_stop, |
| 1038 | .show = show_vfsmnt |
| 1039 | }; |
| 1040 | |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 1041 | static int show_mountinfo(struct seq_file *m, void *v) |
| 1042 | { |
| 1043 | struct proc_mounts *p = m->private; |
| 1044 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
| 1045 | struct super_block *sb = mnt->mnt_sb; |
| 1046 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
| 1047 | struct path root = p->root; |
| 1048 | int err = 0; |
| 1049 | |
| 1050 | seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, |
| 1051 | MAJOR(sb->s_dev), MINOR(sb->s_dev)); |
| 1052 | seq_dentry(m, mnt->mnt_root, " \t\n\\"); |
| 1053 | seq_putc(m, ' '); |
| 1054 | seq_path_root(m, &mnt_path, &root, " \t\n\\"); |
| 1055 | if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { |
| 1056 | /* |
| 1057 | * Mountpoint is outside root, discard that one. Ugly, |
| 1058 | * but less so than trying to do that in iterator in a |
| 1059 | * race-free way (due to renames). |
| 1060 | */ |
| 1061 | return SEQ_SKIP; |
| 1062 | } |
| 1063 | seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); |
| 1064 | show_mnt_opts(m, mnt); |
| 1065 | |
| 1066 | /* Tagged fields ("foo:X" or "bar") */ |
| 1067 | if (IS_MNT_SHARED(mnt)) |
| 1068 | seq_printf(m, " shared:%i", mnt->mnt_group_id); |
Miklos Szeredi | 97e7e0f | 2008-03-27 13:06:26 +0100 | [diff] [blame] | 1069 | if (IS_MNT_SLAVE(mnt)) { |
| 1070 | int master = mnt->mnt_master->mnt_group_id; |
| 1071 | int dom = get_dominating_id(mnt, &p->root); |
| 1072 | seq_printf(m, " master:%i", master); |
| 1073 | if (dom && dom != master) |
| 1074 | seq_printf(m, " propagate_from:%i", dom); |
| 1075 | } |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 1076 | if (IS_MNT_UNBINDABLE(mnt)) |
| 1077 | seq_puts(m, " unbindable"); |
| 1078 | |
| 1079 | /* Filesystem specific data */ |
| 1080 | seq_puts(m, " - "); |
| 1081 | show_type(m, sb); |
| 1082 | seq_putc(m, ' '); |
| 1083 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); |
| 1084 | seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); |
Eric Paris | 2069f45 | 2008-07-04 09:47:13 +1000 | [diff] [blame] | 1085 | err = show_sb_opts(m, sb); |
| 1086 | if (err) |
| 1087 | goto out; |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 1088 | if (sb->s_op->show_options) |
| 1089 | err = sb->s_op->show_options(m, mnt); |
| 1090 | seq_putc(m, '\n'); |
Eric Paris | 2069f45 | 2008-07-04 09:47:13 +1000 | [diff] [blame] | 1091 | out: |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 1092 | return err; |
| 1093 | } |
| 1094 | |
| 1095 | const struct seq_operations mountinfo_op = { |
| 1096 | .start = m_start, |
| 1097 | .next = m_next, |
| 1098 | .stop = m_stop, |
| 1099 | .show = show_mountinfo, |
| 1100 | }; |
| 1101 | |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1102 | static int show_vfsstat(struct seq_file *m, void *v) |
| 1103 | { |
Pavel Emelianov | b0765fb | 2007-07-15 23:39:55 -0700 | [diff] [blame] | 1104 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
Jan Blunck | c32c2f6 | 2008-02-14 19:38:43 -0800 | [diff] [blame] | 1105 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1106 | int err = 0; |
| 1107 | |
| 1108 | /* device */ |
| 1109 | if (mnt->mnt_devname) { |
| 1110 | seq_puts(m, "device "); |
| 1111 | mangle(m, mnt->mnt_devname); |
| 1112 | } else |
| 1113 | seq_puts(m, "no device"); |
| 1114 | |
| 1115 | /* mount point */ |
| 1116 | seq_puts(m, " mounted on "); |
Jan Blunck | c32c2f6 | 2008-02-14 19:38:43 -0800 | [diff] [blame] | 1117 | seq_path(m, &mnt_path, " \t\n\\"); |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1118 | seq_putc(m, ' '); |
| 1119 | |
| 1120 | /* file system type */ |
| 1121 | seq_puts(m, "with fstype "); |
Ram Pai | 2d4d486 | 2008-03-27 13:06:25 +0100 | [diff] [blame] | 1122 | show_type(m, mnt->mnt_sb); |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1123 | |
| 1124 | /* optional statistics */ |
| 1125 | if (mnt->mnt_sb->s_op->show_stats) { |
| 1126 | seq_putc(m, ' '); |
| 1127 | err = mnt->mnt_sb->s_op->show_stats(m, mnt); |
| 1128 | } |
| 1129 | |
| 1130 | seq_putc(m, '\n'); |
| 1131 | return err; |
| 1132 | } |
| 1133 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1134 | const struct seq_operations mountstats_op = { |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1135 | .start = m_start, |
| 1136 | .next = m_next, |
| 1137 | .stop = m_stop, |
| 1138 | .show = show_vfsstat, |
| 1139 | }; |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1140 | #endif /* CONFIG_PROC_FS */ |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1141 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1142 | /** |
| 1143 | * may_umount_tree - check if a mount tree is busy |
| 1144 | * @mnt: root of mount tree |
| 1145 | * |
| 1146 | * This is called to check if a tree of mounts has any |
| 1147 | * open files, pwds, chroots or sub mounts that are |
| 1148 | * busy. |
| 1149 | */ |
| 1150 | int may_umount_tree(struct vfsmount *mnt) |
| 1151 | { |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1152 | int actual_refs = 0; |
| 1153 | int minimum_refs = 0; |
| 1154 | struct vfsmount *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1155 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1156 | /* write lock needed for mnt_get_count */ |
| 1157 | br_write_lock(vfsmount_lock); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1158 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1159 | actual_refs += mnt_get_count(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1160 | minimum_refs += 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1161 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1162 | br_write_unlock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1163 | |
| 1164 | if (actual_refs > minimum_refs) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1165 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1166 | |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1167 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1168 | } |
| 1169 | |
| 1170 | EXPORT_SYMBOL(may_umount_tree); |
| 1171 | |
| 1172 | /** |
| 1173 | * may_umount - check if a mount point is busy |
| 1174 | * @mnt: root of mount |
| 1175 | * |
| 1176 | * This is called to check if a mount point has any |
| 1177 | * open files, pwds, chroots or sub mounts. If the |
| 1178 | * mount has sub mounts this will return busy |
| 1179 | * regardless of whether the sub mounts are busy. |
| 1180 | * |
| 1181 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 1182 | * give false negatives. The main reason why it's here is that we need |
| 1183 | * a non-destructive way to look for easily umountable filesystems. |
| 1184 | */ |
| 1185 | int may_umount(struct vfsmount *mnt) |
| 1186 | { |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1187 | int ret = 1; |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1188 | down_read(&namespace_sem); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1189 | br_write_lock(vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1190 | if (propagate_mount_busy(mnt, 2)) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1191 | ret = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1192 | br_write_unlock(vfsmount_lock); |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1193 | up_read(&namespace_sem); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1194 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1195 | } |
| 1196 | |
| 1197 | EXPORT_SYMBOL(may_umount); |
| 1198 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1199 | void release_mounts(struct list_head *head) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1200 | { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1201 | struct vfsmount *mnt; |
Miklos Szeredi | bf066c7 | 2006-01-08 01:03:19 -0800 | [diff] [blame] | 1202 | while (!list_empty(head)) { |
Pavel Emelianov | b5e6181 | 2007-05-08 00:30:19 -0700 | [diff] [blame] | 1203 | mnt = list_first_entry(head, struct vfsmount, mnt_hash); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1204 | list_del_init(&mnt->mnt_hash); |
| 1205 | if (mnt->mnt_parent != mnt) { |
| 1206 | struct dentry *dentry; |
| 1207 | struct vfsmount *m; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1208 | |
| 1209 | br_write_lock(vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1210 | dentry = mnt->mnt_mountpoint; |
| 1211 | m = mnt->mnt_parent; |
| 1212 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 1213 | mnt->mnt_parent = mnt; |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1214 | m->mnt_ghosts--; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1215 | br_write_unlock(vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1216 | dput(dentry); |
| 1217 | mntput(m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1218 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1219 | mntput_long(mnt); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1220 | } |
| 1221 | } |
| 1222 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1223 | /* |
| 1224 | * vfsmount lock must be held for write |
| 1225 | * namespace_sem must be held for write |
| 1226 | */ |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1227 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1228 | { |
| 1229 | struct vfsmount *p; |
| 1230 | |
Akinobu Mita | 1bfba4e | 2006-06-26 00:24:40 -0700 | [diff] [blame] | 1231 | for (p = mnt; p; p = next_mnt(p, mnt)) |
| 1232 | list_move(&p->mnt_hash, kill); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1233 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1234 | if (propagate) |
| 1235 | propagate_umount(kill); |
| 1236 | |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1237 | list_for_each_entry(p, kill, mnt_hash) { |
| 1238 | list_del_init(&p->mnt_expire); |
| 1239 | list_del_init(&p->mnt_list); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 1240 | __touch_mnt_namespace(p->mnt_ns); |
| 1241 | p->mnt_ns = NULL; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1242 | list_del_init(&p->mnt_child); |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1243 | if (p->mnt_parent != p) { |
| 1244 | p->mnt_parent->mnt_ghosts++; |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 1245 | dentry_reset_mounted(p->mnt_parent, p->mnt_mountpoint); |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1246 | } |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1247 | change_mnt_propagation(p, MS_PRIVATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1248 | } |
| 1249 | } |
| 1250 | |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1251 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts); |
| 1252 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1253 | static int do_umount(struct vfsmount *mnt, int flags) |
| 1254 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1255 | struct super_block *sb = mnt->mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1256 | int retval; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1257 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1258 | |
| 1259 | retval = security_sb_umount(mnt, flags); |
| 1260 | if (retval) |
| 1261 | return retval; |
| 1262 | |
| 1263 | /* |
| 1264 | * Allow userspace to request a mountpoint be expired rather than |
| 1265 | * unmounting unconditionally. Unmount only happens if: |
| 1266 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 1267 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 1268 | */ |
| 1269 | if (flags & MNT_EXPIRE) { |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1270 | if (mnt == current->fs->root.mnt || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1271 | flags & (MNT_FORCE | MNT_DETACH)) |
| 1272 | return -EINVAL; |
| 1273 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1274 | /* |
| 1275 | * probably don't strictly need the lock here if we examined |
| 1276 | * all race cases, but it's a slowpath. |
| 1277 | */ |
| 1278 | br_write_lock(vfsmount_lock); |
| 1279 | if (mnt_get_count(mnt) != 2) { |
| 1280 | br_write_lock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1281 | return -EBUSY; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1282 | } |
| 1283 | br_write_unlock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1284 | |
| 1285 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
| 1286 | return -EAGAIN; |
| 1287 | } |
| 1288 | |
| 1289 | /* |
| 1290 | * If we may have to abort operations to get out of this |
| 1291 | * mount, and they will themselves hold resources we must |
| 1292 | * allow the fs to do things. In the Unix tradition of |
| 1293 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 1294 | * might fail to complete on the first run through as other tasks |
| 1295 | * must return, and the like. Thats for the mount program to worry |
| 1296 | * about for the moment. |
| 1297 | */ |
| 1298 | |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1299 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1300 | sb->s_op->umount_begin(sb); |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1301 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1302 | |
| 1303 | /* |
| 1304 | * No sense to grab the lock for this test, but test itself looks |
| 1305 | * somewhat bogus. Suggestions for better replacement? |
| 1306 | * Ho-hum... In principle, we might treat that as umount + switch |
| 1307 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 1308 | * Actually it makes sense, especially if rootfs would contain a |
| 1309 | * /reboot - static binary that would close all descriptors and |
| 1310 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 1311 | */ |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1312 | if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1313 | /* |
| 1314 | * Special case for "unmounting" root ... |
| 1315 | * we just try to remount it readonly. |
| 1316 | */ |
| 1317 | down_write(&sb->s_umount); |
Al Viro | 4aa98cf | 2009-05-08 13:36:58 -0400 | [diff] [blame] | 1318 | if (!(sb->s_flags & MS_RDONLY)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1319 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1320 | up_write(&sb->s_umount); |
| 1321 | return retval; |
| 1322 | } |
| 1323 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1324 | down_write(&namespace_sem); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1325 | br_write_lock(vfsmount_lock); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1326 | event++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1327 | |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1328 | if (!(flags & MNT_DETACH)) |
| 1329 | shrink_submounts(mnt, &umount_list); |
| 1330 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1331 | retval = -EBUSY; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1332 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1333 | if (!list_empty(&mnt->mnt_list)) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1334 | umount_tree(mnt, 1, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1335 | retval = 0; |
| 1336 | } |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1337 | br_write_unlock(vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1338 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1339 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1340 | return retval; |
| 1341 | } |
| 1342 | |
| 1343 | /* |
| 1344 | * Now umount can handle mount points as well as block devices. |
| 1345 | * This is important for filesystems which use unnamed block devices. |
| 1346 | * |
| 1347 | * We now support a flag for forced unmount like the other 'big iron' |
| 1348 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD |
| 1349 | */ |
| 1350 | |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1351 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1352 | { |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1353 | struct path path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1354 | int retval; |
Miklos Szeredi | db1f05b | 2010-02-10 12:15:53 +0100 | [diff] [blame] | 1355 | int lookup_flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1356 | |
Miklos Szeredi | db1f05b | 2010-02-10 12:15:53 +0100 | [diff] [blame] | 1357 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
| 1358 | return -EINVAL; |
| 1359 | |
| 1360 | if (!(flags & UMOUNT_NOFOLLOW)) |
| 1361 | lookup_flags |= LOOKUP_FOLLOW; |
| 1362 | |
| 1363 | retval = user_path_at(AT_FDCWD, name, lookup_flags, &path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1364 | if (retval) |
| 1365 | goto out; |
| 1366 | retval = -EINVAL; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1367 | if (path.dentry != path.mnt->mnt_root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1368 | goto dput_and_out; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1369 | if (!check_mnt(path.mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1370 | goto dput_and_out; |
| 1371 | |
| 1372 | retval = -EPERM; |
| 1373 | if (!capable(CAP_SYS_ADMIN)) |
| 1374 | goto dput_and_out; |
| 1375 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1376 | retval = do_umount(path.mnt, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1377 | dput_and_out: |
Jan Blunck | 429731b | 2008-02-14 19:34:31 -0800 | [diff] [blame] | 1378 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1379 | dput(path.dentry); |
| 1380 | mntput_no_expire(path.mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1381 | out: |
| 1382 | return retval; |
| 1383 | } |
| 1384 | |
| 1385 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 1386 | |
| 1387 | /* |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1388 | * The 2.0 compatible umount. No flags. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1389 | */ |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1390 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1391 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1392 | return sys_umount(name, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1393 | } |
| 1394 | |
| 1395 | #endif |
| 1396 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1397 | static int mount_is_safe(struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1398 | { |
| 1399 | if (capable(CAP_SYS_ADMIN)) |
| 1400 | return 0; |
| 1401 | return -EPERM; |
| 1402 | #ifdef notyet |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1403 | if (S_ISLNK(path->dentry->d_inode->i_mode)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1404 | return -EPERM; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1405 | if (path->dentry->d_inode->i_mode & S_ISVTX) { |
David Howells | da9592e | 2008-11-14 10:39:05 +1100 | [diff] [blame] | 1406 | if (current_uid() != path->dentry->d_inode->i_uid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1407 | return -EPERM; |
| 1408 | } |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1409 | if (inode_permission(path->dentry->d_inode, MAY_WRITE)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1410 | return -EPERM; |
| 1411 | return 0; |
| 1412 | #endif |
| 1413 | } |
| 1414 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1415 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1416 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1417 | { |
| 1418 | struct vfsmount *res, *p, *q, *r, *s; |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1419 | struct path path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1420 | |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1421 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
| 1422 | return NULL; |
| 1423 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1424 | res = q = clone_mnt(mnt, dentry, flag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1425 | if (!q) |
| 1426 | goto Enomem; |
| 1427 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
| 1428 | |
| 1429 | p = mnt; |
Domen Puncer | fdadd65 | 2005-09-10 00:27:07 -0700 | [diff] [blame] | 1430 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
Jan Blunck | 7ec02ef | 2008-04-29 00:59:40 -0700 | [diff] [blame] | 1431 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1432 | continue; |
| 1433 | |
| 1434 | for (s = r; s; s = next_mnt(s, r)) { |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1435 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
| 1436 | s = skip_mnt_tree(s); |
| 1437 | continue; |
| 1438 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1439 | while (p != s->mnt_parent) { |
| 1440 | p = p->mnt_parent; |
| 1441 | q = q->mnt_parent; |
| 1442 | } |
| 1443 | p = s; |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1444 | path.mnt = q; |
| 1445 | path.dentry = p->mnt_mountpoint; |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1446 | q = clone_mnt(p, p->mnt_root, flag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1447 | if (!q) |
| 1448 | goto Enomem; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1449 | br_write_lock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1450 | list_add_tail(&q->mnt_list, &res->mnt_list); |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1451 | attach_mnt(q, &path); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1452 | br_write_unlock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1453 | } |
| 1454 | } |
| 1455 | return res; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1456 | Enomem: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1457 | if (res) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1458 | LIST_HEAD(umount_list); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1459 | br_write_lock(vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1460 | umount_tree(res, 0, &umount_list); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1461 | br_write_unlock(vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1462 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1463 | } |
| 1464 | return NULL; |
| 1465 | } |
| 1466 | |
Al Viro | 589ff87 | 2009-04-18 03:28:19 -0400 | [diff] [blame] | 1467 | struct vfsmount *collect_mounts(struct path *path) |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1468 | { |
| 1469 | struct vfsmount *tree; |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1470 | down_write(&namespace_sem); |
Al Viro | 589ff87 | 2009-04-18 03:28:19 -0400 | [diff] [blame] | 1471 | tree = copy_tree(path->mnt, path->dentry, CL_COPY_ALL | CL_PRIVATE); |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1472 | up_write(&namespace_sem); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1473 | return tree; |
| 1474 | } |
| 1475 | |
| 1476 | void drop_collected_mounts(struct vfsmount *mnt) |
| 1477 | { |
| 1478 | LIST_HEAD(umount_list); |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1479 | down_write(&namespace_sem); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1480 | br_write_lock(vfsmount_lock); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1481 | umount_tree(mnt, 0, &umount_list); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1482 | br_write_unlock(vfsmount_lock); |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1483 | up_write(&namespace_sem); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1484 | release_mounts(&umount_list); |
| 1485 | } |
| 1486 | |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1487 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
| 1488 | struct vfsmount *root) |
| 1489 | { |
| 1490 | struct vfsmount *mnt; |
| 1491 | int res = f(root, arg); |
| 1492 | if (res) |
| 1493 | return res; |
| 1494 | list_for_each_entry(mnt, &root->mnt_list, mnt_list) { |
| 1495 | res = f(mnt, arg); |
| 1496 | if (res) |
| 1497 | return res; |
| 1498 | } |
| 1499 | return 0; |
| 1500 | } |
| 1501 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1502 | static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) |
| 1503 | { |
| 1504 | struct vfsmount *p; |
| 1505 | |
| 1506 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
| 1507 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
| 1508 | mnt_release_group_id(p); |
| 1509 | } |
| 1510 | } |
| 1511 | |
| 1512 | static int invent_group_ids(struct vfsmount *mnt, bool recurse) |
| 1513 | { |
| 1514 | struct vfsmount *p; |
| 1515 | |
| 1516 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
| 1517 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
| 1518 | int err = mnt_alloc_group_id(p); |
| 1519 | if (err) { |
| 1520 | cleanup_group_ids(mnt, p); |
| 1521 | return err; |
| 1522 | } |
| 1523 | } |
| 1524 | } |
| 1525 | |
| 1526 | return 0; |
| 1527 | } |
| 1528 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1529 | /* |
| 1530 | * @source_mnt : mount tree to be attached |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1531 | * @nd : place the mount tree @source_mnt is attached |
| 1532 | * @parent_nd : if non-null, detach the source_mnt from its parent and |
| 1533 | * store the parent mount and mountpoint dentry. |
| 1534 | * (done when source_mnt is moved) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1535 | * |
| 1536 | * NOTE: in the table below explains the semantics when a source mount |
| 1537 | * of a given type is attached to a destination mount of a given type. |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1538 | * --------------------------------------------------------------------------- |
| 1539 | * | BIND MOUNT OPERATION | |
| 1540 | * |************************************************************************** |
| 1541 | * | source-->| shared | private | slave | unbindable | |
| 1542 | * | dest | | | | | |
| 1543 | * | | | | | | | |
| 1544 | * | v | | | | | |
| 1545 | * |************************************************************************** |
| 1546 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | |
| 1547 | * | | | | | | |
| 1548 | * |non-shared| shared (+) | private | slave (*) | invalid | |
| 1549 | * *************************************************************************** |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1550 | * A bind operation clones the source mount and mounts the clone on the |
| 1551 | * destination mount. |
| 1552 | * |
| 1553 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 1554 | * tree of the destination mount and the cloned mount is added to |
| 1555 | * the peer group of the source mount. |
| 1556 | * (+) the cloned mount is created under the destination mount and is marked |
| 1557 | * as shared. The cloned mount is added to the peer group of the source |
| 1558 | * mount. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1559 | * (+++) the mount is propagated to all the mounts in the propagation tree |
| 1560 | * of the destination mount and the cloned mount is made slave |
| 1561 | * of the same master as that of the source mount. The cloned mount |
| 1562 | * is marked as 'shared and slave'. |
| 1563 | * (*) the cloned mount is made a slave of the same master as that of the |
| 1564 | * source mount. |
| 1565 | * |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1566 | * --------------------------------------------------------------------------- |
| 1567 | * | MOVE MOUNT OPERATION | |
| 1568 | * |************************************************************************** |
| 1569 | * | source-->| shared | private | slave | unbindable | |
| 1570 | * | dest | | | | | |
| 1571 | * | | | | | | | |
| 1572 | * | v | | | | | |
| 1573 | * |************************************************************************** |
| 1574 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | |
| 1575 | * | | | | | | |
| 1576 | * |non-shared| shared (+*) | private | slave (*) | unbindable | |
| 1577 | * *************************************************************************** |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1578 | * |
| 1579 | * (+) the mount is moved to the destination. And is then propagated to |
| 1580 | * all the mounts in the propagation tree of the destination mount. |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1581 | * (+*) the mount is moved to the destination. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1582 | * (+++) the mount is moved to the destination and is then propagated to |
| 1583 | * all the mounts belonging to the destination mount's propagation tree. |
| 1584 | * the mount is marked as 'shared and slave'. |
| 1585 | * (*) the mount continues to be a slave at the new location. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1586 | * |
| 1587 | * if the source mount is a tree, the operations explained above is |
| 1588 | * applied to each mount in the tree. |
| 1589 | * Must be called without spinlocks held, since this function can sleep |
| 1590 | * in allocations. |
| 1591 | */ |
| 1592 | static int attach_recursive_mnt(struct vfsmount *source_mnt, |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1593 | struct path *path, struct path *parent_path) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1594 | { |
| 1595 | LIST_HEAD(tree_list); |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1596 | struct vfsmount *dest_mnt = path->mnt; |
| 1597 | struct dentry *dest_dentry = path->dentry; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1598 | struct vfsmount *child, *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1599 | int err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1600 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1601 | if (IS_MNT_SHARED(dest_mnt)) { |
| 1602 | err = invent_group_ids(source_mnt, true); |
| 1603 | if (err) |
| 1604 | goto out; |
| 1605 | } |
| 1606 | err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); |
| 1607 | if (err) |
| 1608 | goto out_cleanup_ids; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1609 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1610 | br_write_lock(vfsmount_lock); |
Al Viro | df1a1ad | 2010-01-16 12:57:40 -0500 | [diff] [blame] | 1611 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1612 | if (IS_MNT_SHARED(dest_mnt)) { |
| 1613 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
| 1614 | set_mnt_shared(p); |
| 1615 | } |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1616 | if (parent_path) { |
| 1617 | detach_mnt(source_mnt, parent_path); |
| 1618 | attach_mnt(source_mnt, path); |
Al Viro | e5d67f0 | 2009-04-07 12:15:39 -0400 | [diff] [blame] | 1619 | touch_mnt_namespace(parent_path->mnt->mnt_ns); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1620 | } else { |
| 1621 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); |
| 1622 | commit_tree(source_mnt); |
| 1623 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1624 | |
| 1625 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { |
| 1626 | list_del_init(&child->mnt_hash); |
| 1627 | commit_tree(child); |
| 1628 | } |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1629 | br_write_unlock(vfsmount_lock); |
| 1630 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1631 | return 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1632 | |
| 1633 | out_cleanup_ids: |
| 1634 | if (IS_MNT_SHARED(dest_mnt)) |
| 1635 | cleanup_group_ids(source_mnt, NULL); |
| 1636 | out: |
| 1637 | return err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1638 | } |
| 1639 | |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 1640 | static int graft_tree(struct vfsmount *mnt, struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1641 | { |
| 1642 | int err; |
| 1643 | if (mnt->mnt_sb->s_flags & MS_NOUSER) |
| 1644 | return -EINVAL; |
| 1645 | |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 1646 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1647 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) |
| 1648 | return -ENOTDIR; |
| 1649 | |
| 1650 | err = -ENOENT; |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 1651 | mutex_lock(&path->dentry->d_inode->i_mutex); |
Al Viro | d83c49f | 2010-04-30 17:17:09 -0400 | [diff] [blame] | 1652 | if (cant_mount(path->dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1653 | goto out_unlock; |
| 1654 | |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 1655 | if (!d_unlinked(path->dentry)) |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 1656 | err = attach_recursive_mnt(mnt, path, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1657 | out_unlock: |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 1658 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1659 | return err; |
| 1660 | } |
| 1661 | |
| 1662 | /* |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 1663 | * Sanity check the flags to change_mnt_propagation. |
| 1664 | */ |
| 1665 | |
| 1666 | static int flags_to_propagation_type(int flags) |
| 1667 | { |
| 1668 | int type = flags & ~MS_REC; |
| 1669 | |
| 1670 | /* Fail if any non-propagation flags are set */ |
| 1671 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 1672 | return 0; |
| 1673 | /* Only one propagation flag should be set */ |
| 1674 | if (!is_power_of_2(type)) |
| 1675 | return 0; |
| 1676 | return type; |
| 1677 | } |
| 1678 | |
| 1679 | /* |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1680 | * recursively change the type of the mountpoint. |
| 1681 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1682 | static int do_change_type(struct path *path, int flag) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1683 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1684 | struct vfsmount *m, *mnt = path->mnt; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1685 | int recurse = flag & MS_REC; |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 1686 | int type; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1687 | int err = 0; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1688 | |
Miklos Szeredi | ee6f958 | 2007-05-08 00:30:40 -0700 | [diff] [blame] | 1689 | if (!capable(CAP_SYS_ADMIN)) |
| 1690 | return -EPERM; |
| 1691 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1692 | if (path->dentry != path->mnt->mnt_root) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1693 | return -EINVAL; |
| 1694 | |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 1695 | type = flags_to_propagation_type(flag); |
| 1696 | if (!type) |
| 1697 | return -EINVAL; |
| 1698 | |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1699 | down_write(&namespace_sem); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1700 | if (type == MS_SHARED) { |
| 1701 | err = invent_group_ids(mnt, recurse); |
| 1702 | if (err) |
| 1703 | goto out_unlock; |
| 1704 | } |
| 1705 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1706 | br_write_lock(vfsmount_lock); |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1707 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
| 1708 | change_mnt_propagation(m, type); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1709 | br_write_unlock(vfsmount_lock); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1710 | |
| 1711 | out_unlock: |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1712 | up_write(&namespace_sem); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1713 | return err; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1714 | } |
| 1715 | |
| 1716 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1717 | * do loopback mount. |
| 1718 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1719 | static int do_loopback(struct path *path, char *old_name, |
Eric Sandeen | 2dafe1c | 2008-02-08 04:22:12 -0800 | [diff] [blame] | 1720 | int recurse) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1721 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1722 | struct path old_path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1723 | struct vfsmount *mnt = NULL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1724 | int err = mount_is_safe(path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1725 | if (err) |
| 1726 | return err; |
| 1727 | if (!old_name || !*old_name) |
| 1728 | return -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1729 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1730 | if (err) |
| 1731 | return err; |
| 1732 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1733 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1734 | err = -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1735 | if (IS_MNT_UNBINDABLE(old_path.mnt)) |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 1736 | goto out; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1737 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1738 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1739 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1740 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1741 | err = -ENOMEM; |
| 1742 | if (recurse) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1743 | mnt = copy_tree(old_path.mnt, old_path.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1744 | else |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1745 | mnt = clone_mnt(old_path.mnt, old_path.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1746 | |
| 1747 | if (!mnt) |
| 1748 | goto out; |
| 1749 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1750 | err = graft_tree(mnt, path); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1751 | if (err) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1752 | LIST_HEAD(umount_list); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1753 | |
| 1754 | br_write_lock(vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1755 | umount_tree(mnt, 0, &umount_list); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1756 | br_write_unlock(vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1757 | release_mounts(&umount_list); |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1758 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1759 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1760 | out: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1761 | up_write(&namespace_sem); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1762 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1763 | return err; |
| 1764 | } |
| 1765 | |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1766 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
| 1767 | { |
| 1768 | int error = 0; |
| 1769 | int readonly_request = 0; |
| 1770 | |
| 1771 | if (ms_flags & MS_RDONLY) |
| 1772 | readonly_request = 1; |
| 1773 | if (readonly_request == __mnt_is_readonly(mnt)) |
| 1774 | return 0; |
| 1775 | |
| 1776 | if (readonly_request) |
| 1777 | error = mnt_make_readonly(mnt); |
| 1778 | else |
| 1779 | __mnt_unmake_readonly(mnt); |
| 1780 | return error; |
| 1781 | } |
| 1782 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1783 | /* |
| 1784 | * change filesystem flags. dir should be a physical root of filesystem. |
| 1785 | * If you've mounted a non-root directory somewhere and want to do remount |
| 1786 | * on it - tough luck. |
| 1787 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1788 | static int do_remount(struct path *path, int flags, int mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1789 | void *data) |
| 1790 | { |
| 1791 | int err; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1792 | struct super_block *sb = path->mnt->mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1793 | |
| 1794 | if (!capable(CAP_SYS_ADMIN)) |
| 1795 | return -EPERM; |
| 1796 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1797 | if (!check_mnt(path->mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1798 | return -EINVAL; |
| 1799 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1800 | if (path->dentry != path->mnt->mnt_root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1801 | return -EINVAL; |
| 1802 | |
| 1803 | down_write(&sb->s_umount); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1804 | if (flags & MS_BIND) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1805 | err = change_mount_flags(path->mnt, flags); |
Al Viro | 4aa98cf | 2009-05-08 13:36:58 -0400 | [diff] [blame] | 1806 | else |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1807 | err = do_remount_sb(sb, flags, data, 0); |
Al Viro | 7b43a79 | 2010-01-16 13:01:26 -0500 | [diff] [blame] | 1808 | if (!err) { |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1809 | br_write_lock(vfsmount_lock); |
Valerie Aurora | 495d6c9 | 2010-01-26 14:20:47 -0500 | [diff] [blame] | 1810 | mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1811 | path->mnt->mnt_flags = mnt_flags; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1812 | br_write_unlock(vfsmount_lock); |
Al Viro | 7b43a79 | 2010-01-16 13:01:26 -0500 | [diff] [blame] | 1813 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1814 | up_write(&sb->s_umount); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 1815 | if (!err) { |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1816 | br_write_lock(vfsmount_lock); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 1817 | touch_mnt_namespace(path->mnt->mnt_ns); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1818 | br_write_unlock(vfsmount_lock); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 1819 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1820 | return err; |
| 1821 | } |
| 1822 | |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1823 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
| 1824 | { |
| 1825 | struct vfsmount *p; |
| 1826 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 1827 | if (IS_MNT_UNBINDABLE(p)) |
| 1828 | return 1; |
| 1829 | } |
| 1830 | return 0; |
| 1831 | } |
| 1832 | |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1833 | static int do_move_mount(struct path *path, char *old_name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1834 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1835 | struct path old_path, parent_path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1836 | struct vfsmount *p; |
| 1837 | int err = 0; |
| 1838 | if (!capable(CAP_SYS_ADMIN)) |
| 1839 | return -EPERM; |
| 1840 | if (!old_name || !*old_name) |
| 1841 | return -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1842 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1843 | if (err) |
| 1844 | return err; |
| 1845 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1846 | down_write(&namespace_sem); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1847 | while (d_mountpoint(path->dentry) && |
Al Viro | 9393bd0 | 2009-04-18 13:58:15 -0400 | [diff] [blame] | 1848 | follow_down(path)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1849 | ; |
| 1850 | err = -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1851 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1852 | goto out; |
| 1853 | |
| 1854 | err = -ENOENT; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1855 | mutex_lock(&path->dentry->d_inode->i_mutex); |
Al Viro | d83c49f | 2010-04-30 17:17:09 -0400 | [diff] [blame] | 1856 | if (cant_mount(path->dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1857 | goto out1; |
| 1858 | |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 1859 | if (d_unlinked(path->dentry)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1860 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1861 | |
| 1862 | err = -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1863 | if (old_path.dentry != old_path.mnt->mnt_root) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1864 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1865 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1866 | if (old_path.mnt == old_path.mnt->mnt_parent) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1867 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1868 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1869 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
| 1870 | S_ISDIR(old_path.dentry->d_inode->i_mode)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1871 | goto out1; |
| 1872 | /* |
| 1873 | * Don't move a mount residing in a shared parent. |
| 1874 | */ |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1875 | if (old_path.mnt->mnt_parent && |
| 1876 | IS_MNT_SHARED(old_path.mnt->mnt_parent)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1877 | goto out1; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1878 | /* |
| 1879 | * Don't move a mount tree containing unbindable mounts to a destination |
| 1880 | * mount which is shared. |
| 1881 | */ |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1882 | if (IS_MNT_SHARED(path->mnt) && |
| 1883 | tree_contains_unbindable(old_path.mnt)) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1884 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1885 | err = -ELOOP; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1886 | for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent) |
| 1887 | if (p == old_path.mnt) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1888 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1889 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1890 | err = attach_recursive_mnt(old_path.mnt, path, &parent_path); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 1891 | if (err) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1892 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1893 | |
| 1894 | /* if the mount is moved, it should no longer be expire |
| 1895 | * automatically */ |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1896 | list_del_init(&old_path.mnt->mnt_expire); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1897 | out1: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1898 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1899 | out: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1900 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1901 | if (!err) |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1902 | path_put(&parent_path); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1903 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1904 | return err; |
| 1905 | } |
| 1906 | |
| 1907 | /* |
| 1908 | * create a new mount for userspace and request it to be added into the |
| 1909 | * namespace's tree |
| 1910 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1911 | static int do_new_mount(struct path *path, char *type, int flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1912 | int mnt_flags, char *name, void *data) |
| 1913 | { |
| 1914 | struct vfsmount *mnt; |
| 1915 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 1916 | if (!type) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1917 | return -EINVAL; |
| 1918 | |
| 1919 | /* we need capabilities... */ |
| 1920 | if (!capable(CAP_SYS_ADMIN)) |
| 1921 | return -EPERM; |
| 1922 | |
| 1923 | mnt = do_kern_mount(type, flags, name, data); |
| 1924 | if (IS_ERR(mnt)) |
| 1925 | return PTR_ERR(mnt); |
| 1926 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1927 | return do_add_mount(mnt, path, mnt_flags, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1928 | } |
| 1929 | |
| 1930 | /* |
| 1931 | * add a mount into a namespace's mount tree |
| 1932 | * - provide the option of adding the new mount to an expiration list |
| 1933 | */ |
Al Viro | 8d66bf5 | 2008-08-01 09:05:54 -0400 | [diff] [blame] | 1934 | int do_add_mount(struct vfsmount *newmnt, struct path *path, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1935 | int mnt_flags, struct list_head *fslist) |
| 1936 | { |
| 1937 | int err; |
| 1938 | |
Al Viro | 8089352 | 2010-02-05 09:30:46 -0500 | [diff] [blame] | 1939 | mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL); |
Al Viro | 27d55f1 | 2010-01-16 13:07:36 -0500 | [diff] [blame] | 1940 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1941 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1942 | /* Something was mounted here while we slept */ |
Al Viro | 8d66bf5 | 2008-08-01 09:05:54 -0400 | [diff] [blame] | 1943 | while (d_mountpoint(path->dentry) && |
Al Viro | 9393bd0 | 2009-04-18 13:58:15 -0400 | [diff] [blame] | 1944 | follow_down(path)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1945 | ; |
| 1946 | err = -EINVAL; |
Al Viro | dd5cae6 | 2009-04-07 12:21:18 -0400 | [diff] [blame] | 1947 | if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1948 | goto unlock; |
| 1949 | |
| 1950 | /* Refuse the same filesystem on the same mount point */ |
| 1951 | err = -EBUSY; |
Al Viro | 8d66bf5 | 2008-08-01 09:05:54 -0400 | [diff] [blame] | 1952 | if (path->mnt->mnt_sb == newmnt->mnt_sb && |
| 1953 | path->mnt->mnt_root == path->dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1954 | goto unlock; |
| 1955 | |
| 1956 | err = -EINVAL; |
| 1957 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) |
| 1958 | goto unlock; |
| 1959 | |
| 1960 | newmnt->mnt_flags = mnt_flags; |
Al Viro | 8d66bf5 | 2008-08-01 09:05:54 -0400 | [diff] [blame] | 1961 | if ((err = graft_tree(newmnt, path))) |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1962 | goto unlock; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1963 | |
Al Viro | 6758f95 | 2008-03-22 16:14:30 -0400 | [diff] [blame] | 1964 | if (fslist) /* add to the specified expiration list */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1965 | list_add_tail(&newmnt->mnt_expire, fslist); |
Al Viro | 6758f95 | 2008-03-22 16:14:30 -0400 | [diff] [blame] | 1966 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1967 | up_write(&namespace_sem); |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1968 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1969 | |
| 1970 | unlock: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1971 | up_write(&namespace_sem); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1972 | mntput_long(newmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1973 | return err; |
| 1974 | } |
| 1975 | |
| 1976 | EXPORT_SYMBOL_GPL(do_add_mount); |
| 1977 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 1978 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1979 | * process a list of expirable mountpoints with the intent of discarding any |
| 1980 | * mountpoints that aren't in use and haven't been touched since last we came |
| 1981 | * here |
| 1982 | */ |
| 1983 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 1984 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1985 | struct vfsmount *mnt, *next; |
| 1986 | LIST_HEAD(graveyard); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 1987 | LIST_HEAD(umounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1988 | |
| 1989 | if (list_empty(mounts)) |
| 1990 | return; |
| 1991 | |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 1992 | down_write(&namespace_sem); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1993 | br_write_lock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1994 | |
| 1995 | /* extract from the expiration list every vfsmount that matches the |
| 1996 | * following criteria: |
| 1997 | * - only referenced by its parent vfsmount |
| 1998 | * - still marked for expiry (marked on the last call here; marks are |
| 1999 | * cleared by mntput()) |
| 2000 | */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 2001 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2002 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2003 | propagate_mount_busy(mnt, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2004 | continue; |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 2005 | list_move(&mnt->mnt_expire, &graveyard); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2006 | } |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2007 | while (!list_empty(&graveyard)) { |
| 2008 | mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire); |
| 2009 | touch_mnt_namespace(mnt->mnt_ns); |
| 2010 | umount_tree(mnt, 1, &umounts); |
| 2011 | } |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2012 | br_write_unlock(vfsmount_lock); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2013 | up_write(&namespace_sem); |
| 2014 | |
| 2015 | release_mounts(&umounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2016 | } |
| 2017 | |
| 2018 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 2019 | |
| 2020 | /* |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2021 | * Ripoff of 'select_parent()' |
| 2022 | * |
| 2023 | * search the list of submounts for a given mountpoint, and move any |
| 2024 | * shrinkable submounts to the 'graveyard' list. |
| 2025 | */ |
| 2026 | static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) |
| 2027 | { |
| 2028 | struct vfsmount *this_parent = parent; |
| 2029 | struct list_head *next; |
| 2030 | int found = 0; |
| 2031 | |
| 2032 | repeat: |
| 2033 | next = this_parent->mnt_mounts.next; |
| 2034 | resume: |
| 2035 | while (next != &this_parent->mnt_mounts) { |
| 2036 | struct list_head *tmp = next; |
| 2037 | struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); |
| 2038 | |
| 2039 | next = tmp->next; |
| 2040 | if (!(mnt->mnt_flags & MNT_SHRINKABLE)) |
| 2041 | continue; |
| 2042 | /* |
| 2043 | * Descend a level if the d_mounts list is non-empty. |
| 2044 | */ |
| 2045 | if (!list_empty(&mnt->mnt_mounts)) { |
| 2046 | this_parent = mnt; |
| 2047 | goto repeat; |
| 2048 | } |
| 2049 | |
| 2050 | if (!propagate_mount_busy(mnt, 1)) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2051 | list_move_tail(&mnt->mnt_expire, graveyard); |
| 2052 | found++; |
| 2053 | } |
| 2054 | } |
| 2055 | /* |
| 2056 | * All done at this level ... ascend and resume the search |
| 2057 | */ |
| 2058 | if (this_parent != parent) { |
| 2059 | next = this_parent->mnt_child.next; |
| 2060 | this_parent = this_parent->mnt_parent; |
| 2061 | goto resume; |
| 2062 | } |
| 2063 | return found; |
| 2064 | } |
| 2065 | |
| 2066 | /* |
| 2067 | * process a list of expirable mountpoints with the intent of discarding any |
| 2068 | * submounts of a specific parent mountpoint |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2069 | * |
| 2070 | * vfsmount_lock must be held for write |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2071 | */ |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 2072 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2073 | { |
| 2074 | LIST_HEAD(graveyard); |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 2075 | struct vfsmount *m; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2076 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2077 | /* extract submounts of 'mountpoint' from the expiration list */ |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 2078 | while (select_submounts(mnt, &graveyard)) { |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2079 | while (!list_empty(&graveyard)) { |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 2080 | m = list_first_entry(&graveyard, struct vfsmount, |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2081 | mnt_expire); |
Eric W. Biederman | afef80b | 2008-11-12 13:26:54 -0800 | [diff] [blame] | 2082 | touch_mnt_namespace(m->mnt_ns); |
| 2083 | umount_tree(m, 1, umounts); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2084 | } |
| 2085 | } |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2086 | } |
| 2087 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2088 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2089 | * Some copy_from_user() implementations do not return the exact number of |
| 2090 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. |
| 2091 | * Note that this function differs from copy_from_user() in that it will oops |
| 2092 | * on bad values of `to', rather than returning a short copy. |
| 2093 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2094 | static long exact_copy_from_user(void *to, const void __user * from, |
| 2095 | unsigned long n) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2096 | { |
| 2097 | char *t = to; |
| 2098 | const char __user *f = from; |
| 2099 | char c; |
| 2100 | |
| 2101 | if (!access_ok(VERIFY_READ, from, n)) |
| 2102 | return n; |
| 2103 | |
| 2104 | while (n) { |
| 2105 | if (__get_user(c, f)) { |
| 2106 | memset(t, 0, n); |
| 2107 | break; |
| 2108 | } |
| 2109 | *t++ = c; |
| 2110 | f++; |
| 2111 | n--; |
| 2112 | } |
| 2113 | return n; |
| 2114 | } |
| 2115 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2116 | int copy_mount_options(const void __user * data, unsigned long *where) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2117 | { |
| 2118 | int i; |
| 2119 | unsigned long page; |
| 2120 | unsigned long size; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2121 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2122 | *where = 0; |
| 2123 | if (!data) |
| 2124 | return 0; |
| 2125 | |
| 2126 | if (!(page = __get_free_page(GFP_KERNEL))) |
| 2127 | return -ENOMEM; |
| 2128 | |
| 2129 | /* We only care that *some* data at the address the user |
| 2130 | * gave us is valid. Just in case, we'll zero |
| 2131 | * the remainder of the page. |
| 2132 | */ |
| 2133 | /* copy_from_user cannot cross TASK_SIZE ! */ |
| 2134 | size = TASK_SIZE - (unsigned long)data; |
| 2135 | if (size > PAGE_SIZE) |
| 2136 | size = PAGE_SIZE; |
| 2137 | |
| 2138 | i = size - exact_copy_from_user((void *)page, data, size); |
| 2139 | if (!i) { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2140 | free_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2141 | return -EFAULT; |
| 2142 | } |
| 2143 | if (i != PAGE_SIZE) |
| 2144 | memset((char *)page + i, 0, PAGE_SIZE - i); |
| 2145 | *where = page; |
| 2146 | return 0; |
| 2147 | } |
| 2148 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2149 | int copy_mount_string(const void __user *data, char **where) |
| 2150 | { |
| 2151 | char *tmp; |
| 2152 | |
| 2153 | if (!data) { |
| 2154 | *where = NULL; |
| 2155 | return 0; |
| 2156 | } |
| 2157 | |
| 2158 | tmp = strndup_user(data, PAGE_SIZE); |
| 2159 | if (IS_ERR(tmp)) |
| 2160 | return PTR_ERR(tmp); |
| 2161 | |
| 2162 | *where = tmp; |
| 2163 | return 0; |
| 2164 | } |
| 2165 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2166 | /* |
| 2167 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 2168 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 2169 | * |
| 2170 | * data is a (void *) that can point to any structure up to |
| 2171 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 2172 | * information (or be NULL). |
| 2173 | * |
| 2174 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 2175 | * When the flags word was introduced its top half was required |
| 2176 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 2177 | * Therefore, if this magic number is present, it carries no information |
| 2178 | * and must be discarded. |
| 2179 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2180 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2181 | unsigned long flags, void *data_page) |
| 2182 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2183 | struct path path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2184 | int retval = 0; |
| 2185 | int mnt_flags = 0; |
| 2186 | |
| 2187 | /* Discard magic */ |
| 2188 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 2189 | flags &= ~MS_MGC_MSK; |
| 2190 | |
| 2191 | /* Basic sanity checks */ |
| 2192 | |
| 2193 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) |
| 2194 | return -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2195 | |
| 2196 | if (data_page) |
| 2197 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 2198 | |
Tetsuo Handa | a27ab9f2 | 2009-10-04 21:49:49 +0900 | [diff] [blame] | 2199 | /* ... and get the mountpoint */ |
| 2200 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); |
| 2201 | if (retval) |
| 2202 | return retval; |
| 2203 | |
| 2204 | retval = security_sb_mount(dev_name, &path, |
| 2205 | type_page, flags, data_page); |
| 2206 | if (retval) |
| 2207 | goto dput_out; |
| 2208 | |
Andi Kleen | 613cbe3 | 2009-04-19 18:40:43 +0200 | [diff] [blame] | 2209 | /* Default to relatime unless overriden */ |
| 2210 | if (!(flags & MS_NOATIME)) |
| 2211 | mnt_flags |= MNT_RELATIME; |
Matthew Garrett | 0a1c01c | 2009-03-26 17:53:14 +0000 | [diff] [blame] | 2212 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2213 | /* Separate the per-mountpoint flags */ |
| 2214 | if (flags & MS_NOSUID) |
| 2215 | mnt_flags |= MNT_NOSUID; |
| 2216 | if (flags & MS_NODEV) |
| 2217 | mnt_flags |= MNT_NODEV; |
| 2218 | if (flags & MS_NOEXEC) |
| 2219 | mnt_flags |= MNT_NOEXEC; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 2220 | if (flags & MS_NOATIME) |
| 2221 | mnt_flags |= MNT_NOATIME; |
| 2222 | if (flags & MS_NODIRATIME) |
| 2223 | mnt_flags |= MNT_NODIRATIME; |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 2224 | if (flags & MS_STRICTATIME) |
| 2225 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2226 | if (flags & MS_RDONLY) |
| 2227 | mnt_flags |= MNT_READONLY; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 2228 | |
Al Viro | 7a4dec5 | 2010-08-09 12:05:43 -0400 | [diff] [blame] | 2229 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 2230 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
| 2231 | MS_STRICTATIME); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2232 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2233 | if (flags & MS_REMOUNT) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2234 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2235 | data_page); |
| 2236 | else if (flags & MS_BIND) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2237 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2238 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2239 | retval = do_change_type(&path, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2240 | else if (flags & MS_MOVE) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2241 | retval = do_move_mount(&path, dev_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2242 | else |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2243 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2244 | dev_name, data_page); |
| 2245 | dput_out: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2246 | path_put(&path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2247 | return retval; |
| 2248 | } |
| 2249 | |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2250 | static struct mnt_namespace *alloc_mnt_ns(void) |
| 2251 | { |
| 2252 | struct mnt_namespace *new_ns; |
| 2253 | |
| 2254 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); |
| 2255 | if (!new_ns) |
| 2256 | return ERR_PTR(-ENOMEM); |
| 2257 | atomic_set(&new_ns->count, 1); |
| 2258 | new_ns->root = NULL; |
| 2259 | INIT_LIST_HEAD(&new_ns->list); |
| 2260 | init_waitqueue_head(&new_ns->poll); |
| 2261 | new_ns->event = 0; |
| 2262 | return new_ns; |
| 2263 | } |
| 2264 | |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2265 | /* |
| 2266 | * Allocate a new namespace structure and populate it with contents |
| 2267 | * copied from the namespace of the passed in task structure. |
| 2268 | */ |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2269 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2270 | struct fs_struct *fs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2271 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2272 | struct mnt_namespace *new_ns; |
Al Viro | 7f2da1e | 2008-05-10 20:44:54 -0400 | [diff] [blame] | 2273 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2274 | struct vfsmount *p, *q; |
| 2275 | |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2276 | new_ns = alloc_mnt_ns(); |
| 2277 | if (IS_ERR(new_ns)) |
| 2278 | return new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2279 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2280 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2281 | /* First pass: copy the tree topology */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2282 | new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2283 | CL_COPY_ALL | CL_EXPIRE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2284 | if (!new_ns->root) { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2285 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2286 | kfree(new_ns); |
Julia Lawall | 5cc4a03 | 2008-12-01 14:34:51 -0800 | [diff] [blame] | 2287 | return ERR_PTR(-ENOMEM); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2288 | } |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2289 | br_write_lock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2290 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2291 | br_write_unlock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2292 | |
| 2293 | /* |
| 2294 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 2295 | * as belonging to new namespace. We have already acquired a private |
| 2296 | * fs_struct, so tsk->fs->lock is not needed. |
| 2297 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2298 | p = mnt_ns->root; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2299 | q = new_ns->root; |
| 2300 | while (p) { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2301 | q->mnt_ns = new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2302 | if (fs) { |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 2303 | if (p == fs->root.mnt) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2304 | rootmnt = p; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 2305 | fs->root.mnt = mntget_long(q); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2306 | } |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 2307 | if (p == fs->pwd.mnt) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2308 | pwdmnt = p; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 2309 | fs->pwd.mnt = mntget_long(q); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2310 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2311 | } |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2312 | p = next_mnt(p, mnt_ns->root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2313 | q = next_mnt(q, new_ns->root); |
| 2314 | } |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2315 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2316 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2317 | if (rootmnt) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 2318 | mntput_long(rootmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2319 | if (pwdmnt) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 2320 | mntput_long(pwdmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2321 | |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2322 | return new_ns; |
| 2323 | } |
| 2324 | |
Eric W. Biederman | 213dd26 | 2007-07-15 23:41:15 -0700 | [diff] [blame] | 2325 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2326 | struct fs_struct *new_fs) |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2327 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2328 | struct mnt_namespace *new_ns; |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2329 | |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2330 | BUG_ON(!ns); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2331 | get_mnt_ns(ns); |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2332 | |
| 2333 | if (!(flags & CLONE_NEWNS)) |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2334 | return ns; |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2335 | |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2336 | new_ns = dup_mnt_ns(ns, new_fs); |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2337 | |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2338 | put_mnt_ns(ns); |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2339 | return new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2340 | } |
| 2341 | |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2342 | /** |
| 2343 | * create_mnt_ns - creates a private namespace and adds a root filesystem |
| 2344 | * @mnt: pointer to the new root filesystem mountpoint |
| 2345 | */ |
Linus Torvalds | a2770d8 | 2009-12-17 12:51:05 -0800 | [diff] [blame] | 2346 | struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2347 | { |
| 2348 | struct mnt_namespace *new_ns; |
| 2349 | |
| 2350 | new_ns = alloc_mnt_ns(); |
| 2351 | if (!IS_ERR(new_ns)) { |
| 2352 | mnt->mnt_ns = new_ns; |
| 2353 | new_ns->root = mnt; |
| 2354 | list_add(&new_ns->list, &new_ns->root->mnt_list); |
| 2355 | } |
| 2356 | return new_ns; |
| 2357 | } |
Linus Torvalds | a2770d8 | 2009-12-17 12:51:05 -0800 | [diff] [blame] | 2358 | EXPORT_SYMBOL(create_mnt_ns); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2359 | |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 2360 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
| 2361 | char __user *, type, unsigned long, flags, void __user *, data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2362 | { |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2363 | int ret; |
| 2364 | char *kernel_type; |
| 2365 | char *kernel_dir; |
| 2366 | char *kernel_dev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2367 | unsigned long data_page; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2368 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2369 | ret = copy_mount_string(type, &kernel_type); |
| 2370 | if (ret < 0) |
| 2371 | goto out_type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2372 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2373 | kernel_dir = getname(dir_name); |
| 2374 | if (IS_ERR(kernel_dir)) { |
| 2375 | ret = PTR_ERR(kernel_dir); |
| 2376 | goto out_dir; |
| 2377 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2378 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2379 | ret = copy_mount_string(dev_name, &kernel_dev); |
| 2380 | if (ret < 0) |
| 2381 | goto out_dev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2382 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2383 | ret = copy_mount_options(data, &data_page); |
| 2384 | if (ret < 0) |
| 2385 | goto out_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2386 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2387 | ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags, |
| 2388 | (void *) data_page); |
| 2389 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2390 | free_page(data_page); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2391 | out_data: |
| 2392 | kfree(kernel_dev); |
| 2393 | out_dev: |
| 2394 | putname(kernel_dir); |
| 2395 | out_dir: |
| 2396 | kfree(kernel_type); |
| 2397 | out_type: |
| 2398 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2399 | } |
| 2400 | |
| 2401 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2402 | * pivot_root Semantics: |
| 2403 | * Moves the root file system of the current process to the directory put_old, |
| 2404 | * makes new_root as the new root file system of the current process, and sets |
| 2405 | * root/cwd of all processes which had them on the current root to new_root. |
| 2406 | * |
| 2407 | * Restrictions: |
| 2408 | * The new_root and put_old must be directories, and must not be on the |
| 2409 | * same file system as the current process root. The put_old must be |
| 2410 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 2411 | * pointed to by put_old must yield the same directory as new_root. No other |
| 2412 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 2413 | * |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 2414 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
| 2415 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives |
| 2416 | * in this situation. |
| 2417 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2418 | * Notes: |
| 2419 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 2420 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 2421 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 2422 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 2423 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 2424 | * first. |
| 2425 | */ |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 2426 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
| 2427 | const char __user *, put_old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2428 | { |
| 2429 | struct vfsmount *tmp; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2430 | struct path new, old, parent_path, root_parent, root; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2431 | int error; |
| 2432 | |
| 2433 | if (!capable(CAP_SYS_ADMIN)) |
| 2434 | return -EPERM; |
| 2435 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2436 | error = user_path_dir(new_root, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2437 | if (error) |
| 2438 | goto out0; |
| 2439 | error = -EINVAL; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2440 | if (!check_mnt(new.mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2441 | goto out1; |
| 2442 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2443 | error = user_path_dir(put_old, &old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2444 | if (error) |
| 2445 | goto out1; |
| 2446 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2447 | error = security_sb_pivotroot(&old, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2448 | if (error) { |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2449 | path_put(&old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2450 | goto out1; |
| 2451 | } |
| 2452 | |
Miklos Szeredi | f7ad3c6 | 2010-08-10 11:41:36 +0200 | [diff] [blame] | 2453 | get_fs_root(current->fs, &root); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2454 | down_write(&namespace_sem); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2455 | mutex_lock(&old.dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2456 | error = -EINVAL; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2457 | if (IS_MNT_SHARED(old.mnt) || |
| 2458 | IS_MNT_SHARED(new.mnt->mnt_parent) || |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2459 | IS_MNT_SHARED(root.mnt->mnt_parent)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2460 | goto out2; |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2461 | if (!check_mnt(root.mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2462 | goto out2; |
| 2463 | error = -ENOENT; |
Al Viro | d83c49f | 2010-04-30 17:17:09 -0400 | [diff] [blame] | 2464 | if (cant_mount(old.dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2465 | goto out2; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 2466 | if (d_unlinked(new.dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2467 | goto out2; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 2468 | if (d_unlinked(old.dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2469 | goto out2; |
| 2470 | error = -EBUSY; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2471 | if (new.mnt == root.mnt || |
| 2472 | old.mnt == root.mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2473 | goto out2; /* loop, on the same file system */ |
| 2474 | error = -EINVAL; |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2475 | if (root.mnt->mnt_root != root.dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2476 | goto out2; /* not a mountpoint */ |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2477 | if (root.mnt->mnt_parent == root.mnt) |
Miklos Szeredi | 0bb6fcc | 2005-09-06 15:19:36 -0700 | [diff] [blame] | 2478 | goto out2; /* not attached */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2479 | if (new.mnt->mnt_root != new.dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2480 | goto out2; /* not a mountpoint */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2481 | if (new.mnt->mnt_parent == new.mnt) |
Miklos Szeredi | 0bb6fcc | 2005-09-06 15:19:36 -0700 | [diff] [blame] | 2482 | goto out2; /* not attached */ |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2483 | /* make sure we can reach put_old from new_root */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2484 | tmp = old.mnt; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2485 | br_write_lock(vfsmount_lock); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2486 | if (tmp != new.mnt) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2487 | for (;;) { |
| 2488 | if (tmp->mnt_parent == tmp) |
| 2489 | goto out3; /* already mounted on put_old */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2490 | if (tmp->mnt_parent == new.mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2491 | break; |
| 2492 | tmp = tmp->mnt_parent; |
| 2493 | } |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2494 | if (!is_subdir(tmp->mnt_mountpoint, new.dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2495 | goto out3; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2496 | } else if (!is_subdir(old.dentry, new.dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2497 | goto out3; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2498 | detach_mnt(new.mnt, &parent_path); |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2499 | detach_mnt(root.mnt, &root_parent); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2500 | /* mount old root on put_old */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2501 | attach_mnt(root.mnt, &old); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2502 | /* mount new_root on / */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2503 | attach_mnt(new.mnt, &root_parent); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2504 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2505 | br_write_unlock(vfsmount_lock); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2506 | chroot_fs_refs(&root, &new); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 2507 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2508 | error = 0; |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 2509 | path_put(&root_parent); |
| 2510 | path_put(&parent_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2511 | out2: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2512 | mutex_unlock(&old.dentry->d_inode->i_mutex); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2513 | up_write(&namespace_sem); |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2514 | path_put(&root); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2515 | path_put(&old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2516 | out1: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2517 | path_put(&new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2518 | out0: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2519 | return error; |
| 2520 | out3: |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2521 | br_write_unlock(vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2522 | goto out2; |
| 2523 | } |
| 2524 | |
| 2525 | static void __init init_mount_tree(void) |
| 2526 | { |
| 2527 | struct vfsmount *mnt; |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2528 | struct mnt_namespace *ns; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 2529 | struct path root; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2530 | |
| 2531 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); |
| 2532 | if (IS_ERR(mnt)) |
| 2533 | panic("Can't create rootfs"); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 2534 | |
Trond Myklebust | 3b22edc | 2009-06-23 17:29:49 -0400 | [diff] [blame] | 2535 | ns = create_mnt_ns(mnt); |
| 2536 | if (IS_ERR(ns)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2537 | panic("Can't allocate initial namespace"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2538 | |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2539 | init_task.nsproxy->mnt_ns = ns; |
| 2540 | get_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2541 | |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 2542 | root.mnt = ns->root; |
| 2543 | root.dentry = ns->root->mnt_root; |
| 2544 | |
| 2545 | set_fs_pwd(current->fs, &root); |
| 2546 | set_fs_root(current->fs, &root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2547 | } |
| 2548 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 2549 | void __init mnt_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2550 | { |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 2551 | unsigned u; |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 2552 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2553 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2554 | init_rwsem(&namespace_sem); |
| 2555 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2556 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 2557 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2558 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2559 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2560 | |
| 2561 | if (!mount_hashtable) |
| 2562 | panic("Failed to allocate mount hash table\n"); |
| 2563 | |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 2564 | printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2565 | |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 2566 | for (u = 0; u < HASH_SIZE; u++) |
| 2567 | INIT_LIST_HEAD(&mount_hashtable[u]); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2568 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2569 | br_lock_init(vfsmount_lock); |
| 2570 | |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 2571 | err = sysfs_init(); |
| 2572 | if (err) |
| 2573 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 2574 | __func__, err); |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 2575 | fs_kobj = kobject_create_and_add("fs", NULL); |
| 2576 | if (!fs_kobj) |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 2577 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2578 | init_rootfs(); |
| 2579 | init_mount_tree(); |
| 2580 | } |
| 2581 | |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2582 | void put_mnt_ns(struct mnt_namespace *ns) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2583 | { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 2584 | LIST_HEAD(umount_list); |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2585 | |
Al Viro | d498b25 | 2010-02-05 02:21:06 -0500 | [diff] [blame] | 2586 | if (!atomic_dec_and_test(&ns->count)) |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2587 | return; |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2588 | down_write(&namespace_sem); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2589 | br_write_lock(vfsmount_lock); |
Al Viro | d498b25 | 2010-02-05 02:21:06 -0500 | [diff] [blame] | 2590 | umount_tree(ns->root, 0, &umount_list); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2591 | br_write_unlock(vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2592 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 2593 | release_mounts(&umount_list); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2594 | kfree(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2595 | } |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2596 | EXPORT_SYMBOL(put_mnt_ns); |