blob: fe376805cf5f3d877d58c3ff03c103ca0538777d [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/syscalls.h>
12#include <linux/slab.h>
13#include <linux/sched.h>
14#include <linux/smp_lock.h>
15#include <linux/init.h>
Randy Dunlap15a67dd2006-09-29 01:58:57 -070016#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/acct.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080018#include <linux/capability.h>
Dave Hansen3d733632008-02-15 14:37:59 -080019#include <linux/cpumask.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/module.h>
Andrew Mortonf20a9ea2006-08-14 22:43:23 -070021#include <linux/sysfs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/seq_file.h>
Kirill Korotaev6b3286e2006-12-08 02:37:56 -080023#include <linux/mnt_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/namei.h>
25#include <linux/security.h>
26#include <linux/mount.h>
David Howells07f3f052006-09-30 20:52:18 +020027#include <linux/ramfs.h>
Eric Dumazet13f14b42008-02-06 01:37:57 -080028#include <linux/log2.h>
Miklos Szeredi73cd49e2008-03-26 22:11:34 +010029#include <linux/idr.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <asm/uaccess.h>
31#include <asm/unistd.h>
Ram Pai07b20882005-11-07 17:19:07 -050032#include "pnode.h"
Adrian Bunk948730b2007-07-15 23:41:25 -070033#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Eric Dumazet13f14b42008-02-06 01:37:57 -080035#define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head))
36#define HASH_SIZE (1UL << HASH_SHIFT)
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038/* spinlock for vfsmount related operations, inplace of dcache_lock */
Al Viro5addc5d2005-11-07 17:15:49 -050039__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
40
41static int event;
Miklos Szeredi73cd49e2008-03-26 22:11:34 +010042static DEFINE_IDA(mnt_id_ida);
Miklos Szeredi719f5d72008-03-27 13:06:23 +010043static DEFINE_IDA(mnt_group_ida);
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
Eric Dumazetfa3536c2006-03-26 01:37:24 -080045static struct list_head *mount_hashtable __read_mostly;
Christoph Lametere18b8902006-12-06 20:33:20 -080046static struct kmem_cache *mnt_cache __read_mostly;
Ram Pai390c6842005-11-07 17:17:51 -050047static struct rw_semaphore namespace_sem;
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Miklos Szeredif87fd4c2006-01-16 22:14:23 -080049/* /sys/fs */
Greg Kroah-Hartman00d26662007-10-29 14:17:23 -060050struct kobject *fs_kobj;
51EXPORT_SYMBOL_GPL(fs_kobj);
Miklos Szeredif87fd4c2006-01-16 22:14:23 -080052
Linus Torvalds1da177e2005-04-16 15:20:36 -070053static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
54{
Ram Paib58fed82005-11-07 17:16:09 -050055 unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
56 tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
Eric Dumazet13f14b42008-02-06 01:37:57 -080057 tmp = tmp + (tmp >> HASH_SHIFT);
58 return tmp & (HASH_SIZE - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059}
60
Dave Hansen3d733632008-02-15 14:37:59 -080061#define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16)
62
Miklos Szeredi73cd49e2008-03-26 22:11:34 +010063/* allocation is serialized by namespace_sem */
64static int mnt_alloc_id(struct vfsmount *mnt)
65{
66 int res;
67
68retry:
69 ida_pre_get(&mnt_id_ida, GFP_KERNEL);
70 spin_lock(&vfsmount_lock);
71 res = ida_get_new(&mnt_id_ida, &mnt->mnt_id);
72 spin_unlock(&vfsmount_lock);
73 if (res == -EAGAIN)
74 goto retry;
75
76 return res;
77}
78
79static void mnt_free_id(struct vfsmount *mnt)
80{
81 spin_lock(&vfsmount_lock);
82 ida_remove(&mnt_id_ida, mnt->mnt_id);
83 spin_unlock(&vfsmount_lock);
84}
85
Miklos Szeredi719f5d72008-03-27 13:06:23 +010086/*
87 * Allocate a new peer group ID
88 *
89 * mnt_group_ida is protected by namespace_sem
90 */
91static int mnt_alloc_group_id(struct vfsmount *mnt)
92{
93 if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL))
94 return -ENOMEM;
95
96 return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id);
97}
98
99/*
100 * Release a peer group ID
101 */
102void mnt_release_group_id(struct vfsmount *mnt)
103{
104 ida_remove(&mnt_group_ida, mnt->mnt_group_id);
105 mnt->mnt_group_id = 0;
106}
107
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108struct vfsmount *alloc_vfsmnt(const char *name)
109{
Robert P. J. Dayc3762222007-02-10 01:45:03 -0800110 struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 if (mnt) {
Miklos Szeredi73cd49e2008-03-26 22:11:34 +0100112 int err;
113
114 err = mnt_alloc_id(mnt);
115 if (err) {
116 kmem_cache_free(mnt_cache, mnt);
117 return NULL;
118 }
119
Ram Paib58fed82005-11-07 17:16:09 -0500120 atomic_set(&mnt->mnt_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 INIT_LIST_HEAD(&mnt->mnt_hash);
122 INIT_LIST_HEAD(&mnt->mnt_child);
123 INIT_LIST_HEAD(&mnt->mnt_mounts);
124 INIT_LIST_HEAD(&mnt->mnt_list);
Miklos Szeredi55e700b2005-07-07 17:57:30 -0700125 INIT_LIST_HEAD(&mnt->mnt_expire);
Ram Pai03e06e62005-11-07 17:19:33 -0500126 INIT_LIST_HEAD(&mnt->mnt_share);
Ram Paia58b0eb2005-11-07 17:20:48 -0500127 INIT_LIST_HEAD(&mnt->mnt_slave_list);
128 INIT_LIST_HEAD(&mnt->mnt_slave);
Dave Hansen3d733632008-02-15 14:37:59 -0800129 atomic_set(&mnt->__mnt_writers, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 if (name) {
Ram Paib58fed82005-11-07 17:16:09 -0500131 int size = strlen(name) + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 char *newname = kmalloc(size, GFP_KERNEL);
133 if (newname) {
134 memcpy(newname, name, size);
135 mnt->mnt_devname = newname;
136 }
137 }
138 }
139 return mnt;
140}
141
Dave Hansen83660252008-02-15 14:37:30 -0800142/*
143 * Most r/o checks on a fs are for operations that take
144 * discrete amounts of time, like a write() or unlink().
145 * We must keep track of when those operations start
146 * (for permission checks) and when they end, so that
147 * we can determine when writes are able to occur to
148 * a filesystem.
149 */
Dave Hansen3d733632008-02-15 14:37:59 -0800150/*
151 * __mnt_is_readonly: check whether a mount is read-only
152 * @mnt: the mount to check for its write status
153 *
154 * This shouldn't be used directly ouside of the VFS.
155 * It does not guarantee that the filesystem will stay
156 * r/w, just that it is right *now*. This can not and
157 * should not be used in place of IS_RDONLY(inode).
158 * mnt_want/drop_write() will _keep_ the filesystem
159 * r/w.
160 */
161int __mnt_is_readonly(struct vfsmount *mnt)
162{
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800163 if (mnt->mnt_flags & MNT_READONLY)
164 return 1;
165 if (mnt->mnt_sb->s_flags & MS_RDONLY)
166 return 1;
167 return 0;
Dave Hansen3d733632008-02-15 14:37:59 -0800168}
169EXPORT_SYMBOL_GPL(__mnt_is_readonly);
170
171struct mnt_writer {
172 /*
173 * If holding multiple instances of this lock, they
174 * must be ordered by cpu number.
175 */
176 spinlock_t lock;
177 struct lock_class_key lock_class; /* compiles out with !lockdep */
178 unsigned long count;
179 struct vfsmount *mnt;
180} ____cacheline_aligned_in_smp;
181static DEFINE_PER_CPU(struct mnt_writer, mnt_writers);
182
183static int __init init_mnt_writers(void)
184{
185 int cpu;
186 for_each_possible_cpu(cpu) {
187 struct mnt_writer *writer = &per_cpu(mnt_writers, cpu);
188 spin_lock_init(&writer->lock);
189 lockdep_set_class(&writer->lock, &writer->lock_class);
190 writer->count = 0;
191 }
192 return 0;
193}
194fs_initcall(init_mnt_writers);
195
196static void unlock_mnt_writers(void)
197{
198 int cpu;
199 struct mnt_writer *cpu_writer;
200
201 for_each_possible_cpu(cpu) {
202 cpu_writer = &per_cpu(mnt_writers, cpu);
203 spin_unlock(&cpu_writer->lock);
204 }
205}
206
207static inline void __clear_mnt_count(struct mnt_writer *cpu_writer)
208{
209 if (!cpu_writer->mnt)
210 return;
211 /*
212 * This is in case anyone ever leaves an invalid,
213 * old ->mnt and a count of 0.
214 */
215 if (!cpu_writer->count)
216 return;
217 atomic_add(cpu_writer->count, &cpu_writer->mnt->__mnt_writers);
218 cpu_writer->count = 0;
219}
220 /*
221 * must hold cpu_writer->lock
222 */
223static inline void use_cpu_writer_for_mount(struct mnt_writer *cpu_writer,
224 struct vfsmount *mnt)
225{
226 if (cpu_writer->mnt == mnt)
227 return;
228 __clear_mnt_count(cpu_writer);
229 cpu_writer->mnt = mnt;
230}
231
232/*
233 * Most r/o checks on a fs are for operations that take
234 * discrete amounts of time, like a write() or unlink().
235 * We must keep track of when those operations start
236 * (for permission checks) and when they end, so that
237 * we can determine when writes are able to occur to
238 * a filesystem.
239 */
Dave Hansen83660252008-02-15 14:37:30 -0800240/**
241 * mnt_want_write - get write access to a mount
242 * @mnt: the mount on which to take a write
243 *
244 * This tells the low-level filesystem that a write is
245 * about to be performed to it, and makes sure that
246 * writes are allowed before returning success. When
247 * the write operation is finished, mnt_drop_write()
248 * must be called. This is effectively a refcount.
249 */
250int mnt_want_write(struct vfsmount *mnt)
251{
Dave Hansen3d733632008-02-15 14:37:59 -0800252 int ret = 0;
253 struct mnt_writer *cpu_writer;
254
255 cpu_writer = &get_cpu_var(mnt_writers);
256 spin_lock(&cpu_writer->lock);
257 if (__mnt_is_readonly(mnt)) {
258 ret = -EROFS;
259 goto out;
260 }
261 use_cpu_writer_for_mount(cpu_writer, mnt);
262 cpu_writer->count++;
263out:
264 spin_unlock(&cpu_writer->lock);
265 put_cpu_var(mnt_writers);
266 return ret;
Dave Hansen83660252008-02-15 14:37:30 -0800267}
268EXPORT_SYMBOL_GPL(mnt_want_write);
269
Dave Hansen3d733632008-02-15 14:37:59 -0800270static void lock_mnt_writers(void)
271{
272 int cpu;
273 struct mnt_writer *cpu_writer;
274
275 for_each_possible_cpu(cpu) {
276 cpu_writer = &per_cpu(mnt_writers, cpu);
277 spin_lock(&cpu_writer->lock);
278 __clear_mnt_count(cpu_writer);
279 cpu_writer->mnt = NULL;
280 }
281}
282
283/*
284 * These per-cpu write counts are not guaranteed to have
285 * matched increments and decrements on any given cpu.
286 * A file open()ed for write on one cpu and close()d on
287 * another cpu will imbalance this count. Make sure it
288 * does not get too far out of whack.
289 */
290static void handle_write_count_underflow(struct vfsmount *mnt)
291{
292 if (atomic_read(&mnt->__mnt_writers) >=
293 MNT_WRITER_UNDERFLOW_LIMIT)
294 return;
295 /*
296 * It isn't necessary to hold all of the locks
297 * at the same time, but doing it this way makes
298 * us share a lot more code.
299 */
300 lock_mnt_writers();
301 /*
302 * vfsmount_lock is for mnt_flags.
303 */
304 spin_lock(&vfsmount_lock);
305 /*
306 * If coalescing the per-cpu writer counts did not
307 * get us back to a positive writer count, we have
308 * a bug.
309 */
310 if ((atomic_read(&mnt->__mnt_writers) < 0) &&
311 !(mnt->mnt_flags & MNT_IMBALANCED_WRITE_COUNT)) {
312 printk(KERN_DEBUG "leak detected on mount(%p) writers "
313 "count: %d\n",
314 mnt, atomic_read(&mnt->__mnt_writers));
315 WARN_ON(1);
316 /* use the flag to keep the dmesg spam down */
317 mnt->mnt_flags |= MNT_IMBALANCED_WRITE_COUNT;
318 }
319 spin_unlock(&vfsmount_lock);
320 unlock_mnt_writers();
321}
322
Dave Hansen83660252008-02-15 14:37:30 -0800323/**
324 * mnt_drop_write - give up write access to a mount
325 * @mnt: the mount on which to give up write access
326 *
327 * Tells the low-level filesystem that we are done
328 * performing writes to it. Must be matched with
329 * mnt_want_write() call above.
330 */
331void mnt_drop_write(struct vfsmount *mnt)
332{
Dave Hansen3d733632008-02-15 14:37:59 -0800333 int must_check_underflow = 0;
334 struct mnt_writer *cpu_writer;
335
336 cpu_writer = &get_cpu_var(mnt_writers);
337 spin_lock(&cpu_writer->lock);
338
339 use_cpu_writer_for_mount(cpu_writer, mnt);
340 if (cpu_writer->count > 0) {
341 cpu_writer->count--;
342 } else {
343 must_check_underflow = 1;
344 atomic_dec(&mnt->__mnt_writers);
345 }
346
347 spin_unlock(&cpu_writer->lock);
348 /*
349 * Logically, we could call this each time,
350 * but the __mnt_writers cacheline tends to
351 * be cold, and makes this expensive.
352 */
353 if (must_check_underflow)
354 handle_write_count_underflow(mnt);
355 /*
356 * This could be done right after the spinlock
357 * is taken because the spinlock keeps us on
358 * the cpu, and disables preemption. However,
359 * putting it here bounds the amount that
360 * __mnt_writers can underflow. Without it,
361 * we could theoretically wrap __mnt_writers.
362 */
363 put_cpu_var(mnt_writers);
Dave Hansen83660252008-02-15 14:37:30 -0800364}
365EXPORT_SYMBOL_GPL(mnt_drop_write);
366
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800367static int mnt_make_readonly(struct vfsmount *mnt)
Dave Hansen83660252008-02-15 14:37:30 -0800368{
Dave Hansen3d733632008-02-15 14:37:59 -0800369 int ret = 0;
370
371 lock_mnt_writers();
372 /*
373 * With all the locks held, this value is stable
374 */
375 if (atomic_read(&mnt->__mnt_writers) > 0) {
376 ret = -EBUSY;
377 goto out;
378 }
379 /*
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800380 * nobody can do a successful mnt_want_write() with all
381 * of the counts in MNT_DENIED_WRITE and the locks held.
Dave Hansen3d733632008-02-15 14:37:59 -0800382 */
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800383 spin_lock(&vfsmount_lock);
384 if (!ret)
385 mnt->mnt_flags |= MNT_READONLY;
386 spin_unlock(&vfsmount_lock);
Dave Hansen3d733632008-02-15 14:37:59 -0800387out:
388 unlock_mnt_writers();
389 return ret;
Dave Hansen83660252008-02-15 14:37:30 -0800390}
Dave Hansen83660252008-02-15 14:37:30 -0800391
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800392static void __mnt_unmake_readonly(struct vfsmount *mnt)
393{
394 spin_lock(&vfsmount_lock);
395 mnt->mnt_flags &= ~MNT_READONLY;
396 spin_unlock(&vfsmount_lock);
397}
398
David Howells454e2392006-06-23 02:02:57 -0700399int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
400{
401 mnt->mnt_sb = sb;
402 mnt->mnt_root = dget(sb->s_root);
403 return 0;
404}
405
406EXPORT_SYMBOL(simple_set_mnt);
407
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408void free_vfsmnt(struct vfsmount *mnt)
409{
410 kfree(mnt->mnt_devname);
Miklos Szeredi73cd49e2008-03-26 22:11:34 +0100411 mnt_free_id(mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 kmem_cache_free(mnt_cache, mnt);
413}
414
415/*
Ram Paia05964f2005-11-07 17:20:17 -0500416 * find the first or last mount at @dentry on vfsmount @mnt depending on
417 * @dir. If @dir is set return the first mount else return the last mount.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 */
Ram Paia05964f2005-11-07 17:20:17 -0500419struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
420 int dir)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421{
Ram Paib58fed82005-11-07 17:16:09 -0500422 struct list_head *head = mount_hashtable + hash(mnt, dentry);
423 struct list_head *tmp = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 struct vfsmount *p, *found = NULL;
425
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 for (;;) {
Ram Paia05964f2005-11-07 17:20:17 -0500427 tmp = dir ? tmp->next : tmp->prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 p = NULL;
429 if (tmp == head)
430 break;
431 p = list_entry(tmp, struct vfsmount, mnt_hash);
432 if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
Ram Paia05964f2005-11-07 17:20:17 -0500433 found = p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 break;
435 }
436 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 return found;
438}
439
Ram Paia05964f2005-11-07 17:20:17 -0500440/*
441 * lookup_mnt increments the ref count before returning
442 * the vfsmount struct.
443 */
444struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
445{
446 struct vfsmount *child_mnt;
447 spin_lock(&vfsmount_lock);
448 if ((child_mnt = __lookup_mnt(mnt, dentry, 1)))
449 mntget(child_mnt);
450 spin_unlock(&vfsmount_lock);
451 return child_mnt;
452}
453
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454static inline int check_mnt(struct vfsmount *mnt)
455{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800456 return mnt->mnt_ns == current->nsproxy->mnt_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457}
458
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800459static void touch_mnt_namespace(struct mnt_namespace *ns)
Al Viro5addc5d2005-11-07 17:15:49 -0500460{
461 if (ns) {
462 ns->event = ++event;
463 wake_up_interruptible(&ns->poll);
464 }
465}
466
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800467static void __touch_mnt_namespace(struct mnt_namespace *ns)
Al Viro5addc5d2005-11-07 17:15:49 -0500468{
469 if (ns && ns->event != event) {
470 ns->event = event;
471 wake_up_interruptible(&ns->poll);
472 }
473}
474
Al Viro1a390682008-03-21 20:48:19 -0400475static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476{
Al Viro1a390682008-03-21 20:48:19 -0400477 old_path->dentry = mnt->mnt_mountpoint;
478 old_path->mnt = mnt->mnt_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 mnt->mnt_parent = mnt;
480 mnt->mnt_mountpoint = mnt->mnt_root;
481 list_del_init(&mnt->mnt_child);
482 list_del_init(&mnt->mnt_hash);
Al Viro1a390682008-03-21 20:48:19 -0400483 old_path->dentry->d_mounted--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484}
485
Ram Paib90fa9a2005-11-07 17:19:50 -0500486void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
487 struct vfsmount *child_mnt)
488{
489 child_mnt->mnt_parent = mntget(mnt);
490 child_mnt->mnt_mountpoint = dget(dentry);
491 dentry->d_mounted++;
492}
493
Al Viro1a390682008-03-21 20:48:19 -0400494static void attach_mnt(struct vfsmount *mnt, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495{
Al Viro1a390682008-03-21 20:48:19 -0400496 mnt_set_mountpoint(path->mnt, path->dentry, mnt);
Ram Paib90fa9a2005-11-07 17:19:50 -0500497 list_add_tail(&mnt->mnt_hash, mount_hashtable +
Al Viro1a390682008-03-21 20:48:19 -0400498 hash(path->mnt, path->dentry));
499 list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
Ram Paib90fa9a2005-11-07 17:19:50 -0500500}
501
502/*
503 * the caller must hold vfsmount_lock
504 */
505static void commit_tree(struct vfsmount *mnt)
506{
507 struct vfsmount *parent = mnt->mnt_parent;
508 struct vfsmount *m;
509 LIST_HEAD(head);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800510 struct mnt_namespace *n = parent->mnt_ns;
Ram Paib90fa9a2005-11-07 17:19:50 -0500511
512 BUG_ON(parent == mnt);
513
514 list_add_tail(&head, &mnt->mnt_list);
515 list_for_each_entry(m, &head, mnt_list)
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800516 m->mnt_ns = n;
Ram Paib90fa9a2005-11-07 17:19:50 -0500517 list_splice(&head, n->list.prev);
518
519 list_add_tail(&mnt->mnt_hash, mount_hashtable +
520 hash(parent, mnt->mnt_mountpoint));
521 list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800522 touch_mnt_namespace(n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523}
524
525static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
526{
527 struct list_head *next = p->mnt_mounts.next;
528 if (next == &p->mnt_mounts) {
529 while (1) {
530 if (p == root)
531 return NULL;
532 next = p->mnt_child.next;
533 if (next != &p->mnt_parent->mnt_mounts)
534 break;
535 p = p->mnt_parent;
536 }
537 }
538 return list_entry(next, struct vfsmount, mnt_child);
539}
540
Ram Pai9676f0c2005-11-07 17:21:20 -0500541static struct vfsmount *skip_mnt_tree(struct vfsmount *p)
542{
543 struct list_head *prev = p->mnt_mounts.prev;
544 while (prev != &p->mnt_mounts) {
545 p = list_entry(prev, struct vfsmount, mnt_child);
546 prev = p->mnt_mounts.prev;
547 }
548 return p;
549}
550
Ram Pai36341f62005-11-07 17:17:22 -0500551static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
552 int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553{
554 struct super_block *sb = old->mnt_sb;
555 struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
556
557 if (mnt) {
Miklos Szeredi719f5d72008-03-27 13:06:23 +0100558 if (flag & (CL_SLAVE | CL_PRIVATE))
559 mnt->mnt_group_id = 0; /* not a peer of original */
560 else
561 mnt->mnt_group_id = old->mnt_group_id;
562
563 if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
564 int err = mnt_alloc_group_id(mnt);
565 if (err)
566 goto out_free;
567 }
568
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 mnt->mnt_flags = old->mnt_flags;
570 atomic_inc(&sb->s_active);
571 mnt->mnt_sb = sb;
572 mnt->mnt_root = dget(root);
573 mnt->mnt_mountpoint = mnt->mnt_root;
574 mnt->mnt_parent = mnt;
Ram Paib90fa9a2005-11-07 17:19:50 -0500575
Ram Pai5afe0022005-11-07 17:21:01 -0500576 if (flag & CL_SLAVE) {
577 list_add(&mnt->mnt_slave, &old->mnt_slave_list);
578 mnt->mnt_master = old;
579 CLEAR_MNT_SHARED(mnt);
Al Viro8aec0802007-06-07 12:20:32 -0400580 } else if (!(flag & CL_PRIVATE)) {
Ram Pai5afe0022005-11-07 17:21:01 -0500581 if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
582 list_add(&mnt->mnt_share, &old->mnt_share);
583 if (IS_MNT_SLAVE(old))
584 list_add(&mnt->mnt_slave, &old->mnt_slave);
585 mnt->mnt_master = old->mnt_master;
586 }
Ram Paib90fa9a2005-11-07 17:19:50 -0500587 if (flag & CL_MAKE_SHARED)
588 set_mnt_shared(mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589
590 /* stick the duplicate mount on the same expiry list
591 * as the original if that was on one */
Ram Pai36341f62005-11-07 17:17:22 -0500592 if (flag & CL_EXPIRE) {
Ram Pai36341f62005-11-07 17:17:22 -0500593 if (!list_empty(&old->mnt_expire))
594 list_add(&mnt->mnt_expire, &old->mnt_expire);
Ram Pai36341f62005-11-07 17:17:22 -0500595 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 }
597 return mnt;
Miklos Szeredi719f5d72008-03-27 13:06:23 +0100598
599 out_free:
600 free_vfsmnt(mnt);
601 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602}
603
Al Viro7b7b1ac2005-11-07 17:13:39 -0500604static inline void __mntput(struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605{
Dave Hansen3d733632008-02-15 14:37:59 -0800606 int cpu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 struct super_block *sb = mnt->mnt_sb;
Dave Hansen3d733632008-02-15 14:37:59 -0800608 /*
609 * We don't have to hold all of the locks at the
610 * same time here because we know that we're the
611 * last reference to mnt and that no new writers
612 * can come in.
613 */
614 for_each_possible_cpu(cpu) {
615 struct mnt_writer *cpu_writer = &per_cpu(mnt_writers, cpu);
616 if (cpu_writer->mnt != mnt)
617 continue;
618 spin_lock(&cpu_writer->lock);
619 atomic_add(cpu_writer->count, &mnt->__mnt_writers);
620 cpu_writer->count = 0;
621 /*
622 * Might as well do this so that no one
623 * ever sees the pointer and expects
624 * it to be valid.
625 */
626 cpu_writer->mnt = NULL;
627 spin_unlock(&cpu_writer->lock);
628 }
629 /*
630 * This probably indicates that somebody messed
631 * up a mnt_want/drop_write() pair. If this
632 * happens, the filesystem was probably unable
633 * to make r/w->r/o transitions.
634 */
635 WARN_ON(atomic_read(&mnt->__mnt_writers));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 dput(mnt->mnt_root);
637 free_vfsmnt(mnt);
638 deactivate_super(sb);
639}
640
Al Viro7b7b1ac2005-11-07 17:13:39 -0500641void mntput_no_expire(struct vfsmount *mnt)
642{
643repeat:
644 if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
645 if (likely(!mnt->mnt_pinned)) {
646 spin_unlock(&vfsmount_lock);
647 __mntput(mnt);
648 return;
649 }
650 atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
651 mnt->mnt_pinned = 0;
652 spin_unlock(&vfsmount_lock);
653 acct_auto_close_mnt(mnt);
654 security_sb_umount_close(mnt);
655 goto repeat;
656 }
657}
658
659EXPORT_SYMBOL(mntput_no_expire);
660
661void mnt_pin(struct vfsmount *mnt)
662{
663 spin_lock(&vfsmount_lock);
664 mnt->mnt_pinned++;
665 spin_unlock(&vfsmount_lock);
666}
667
668EXPORT_SYMBOL(mnt_pin);
669
670void mnt_unpin(struct vfsmount *mnt)
671{
672 spin_lock(&vfsmount_lock);
673 if (mnt->mnt_pinned) {
674 atomic_inc(&mnt->mnt_count);
675 mnt->mnt_pinned--;
676 }
677 spin_unlock(&vfsmount_lock);
678}
679
680EXPORT_SYMBOL(mnt_unpin);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681
Miklos Szeredib3b304a2008-02-08 04:21:35 -0800682static inline void mangle(struct seq_file *m, const char *s)
683{
684 seq_escape(m, s, " \t\n\\");
685}
686
687/*
688 * Simple .show_options callback for filesystems which don't want to
689 * implement more complex mount option showing.
690 *
691 * See also save_mount_options().
692 */
693int generic_show_options(struct seq_file *m, struct vfsmount *mnt)
694{
695 const char *options = mnt->mnt_sb->s_options;
696
697 if (options != NULL && options[0]) {
698 seq_putc(m, ',');
699 mangle(m, options);
700 }
701
702 return 0;
703}
704EXPORT_SYMBOL(generic_show_options);
705
706/*
707 * If filesystem uses generic_show_options(), this function should be
708 * called from the fill_super() callback.
709 *
710 * The .remount_fs callback usually needs to be handled in a special
711 * way, to make sure, that previous options are not overwritten if the
712 * remount fails.
713 *
714 * Also note, that if the filesystem's .remount_fs function doesn't
715 * reset all options to their default value, but changes only newly
716 * given options, then the displayed options will not reflect reality
717 * any more.
718 */
719void save_mount_options(struct super_block *sb, char *options)
720{
721 kfree(sb->s_options);
722 sb->s_options = kstrdup(options, GFP_KERNEL);
723}
724EXPORT_SYMBOL(save_mount_options);
725
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100726#ifdef CONFIG_PROC_FS
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727/* iterator */
728static void *m_start(struct seq_file *m, loff_t *pos)
729{
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100730 struct proc_mounts *p = m->private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
Ram Pai390c6842005-11-07 17:17:51 -0500732 down_read(&namespace_sem);
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100733 return seq_list_start(&p->ns->list, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734}
735
736static void *m_next(struct seq_file *m, void *v, loff_t *pos)
737{
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100738 struct proc_mounts *p = m->private;
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700739
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100740 return seq_list_next(v, &p->ns->list, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741}
742
743static void m_stop(struct seq_file *m, void *v)
744{
Ram Pai390c6842005-11-07 17:17:51 -0500745 up_read(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746}
747
Ram Pai2d4d4862008-03-27 13:06:25 +0100748struct proc_fs_info {
749 int flag;
750 const char *str;
751};
752
753static void show_sb_opts(struct seq_file *m, struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754{
Ram Pai2d4d4862008-03-27 13:06:25 +0100755 static const struct proc_fs_info fs_info[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756 { MS_SYNCHRONOUS, ",sync" },
757 { MS_DIRSYNC, ",dirsync" },
758 { MS_MANDLOCK, ",mand" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 { 0, NULL }
760 };
Ram Pai2d4d4862008-03-27 13:06:25 +0100761 const struct proc_fs_info *fs_infop;
762
763 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
764 if (sb->s_flags & fs_infop->flag)
765 seq_puts(m, fs_infop->str);
766 }
767}
768
769static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
770{
771 static const struct proc_fs_info mnt_info[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772 { MNT_NOSUID, ",nosuid" },
773 { MNT_NODEV, ",nodev" },
774 { MNT_NOEXEC, ",noexec" },
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -0800775 { MNT_NOATIME, ",noatime" },
776 { MNT_NODIRATIME, ",nodiratime" },
Valerie Henson47ae32d2006-12-13 00:34:34 -0800777 { MNT_RELATIME, ",relatime" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 { 0, NULL }
779 };
Ram Pai2d4d4862008-03-27 13:06:25 +0100780 const struct proc_fs_info *fs_infop;
781
782 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
783 if (mnt->mnt_flags & fs_infop->flag)
784 seq_puts(m, fs_infop->str);
785 }
786}
787
788static void show_type(struct seq_file *m, struct super_block *sb)
789{
790 mangle(m, sb->s_type->name);
791 if (sb->s_subtype && sb->s_subtype[0]) {
792 seq_putc(m, '.');
793 mangle(m, sb->s_subtype);
794 }
795}
796
797static int show_vfsmnt(struct seq_file *m, void *v)
798{
799 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
800 int err = 0;
Jan Blunckc32c2f62008-02-14 19:38:43 -0800801 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802
803 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
804 seq_putc(m, ' ');
Jan Blunckc32c2f62008-02-14 19:38:43 -0800805 seq_path(m, &mnt_path, " \t\n\\");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 seq_putc(m, ' ');
Ram Pai2d4d4862008-03-27 13:06:25 +0100807 show_type(m, mnt->mnt_sb);
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800808 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
Ram Pai2d4d4862008-03-27 13:06:25 +0100809 show_sb_opts(m, mnt->mnt_sb);
810 show_mnt_opts(m, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811 if (mnt->mnt_sb->s_op->show_options)
812 err = mnt->mnt_sb->s_op->show_options(m, mnt);
813 seq_puts(m, " 0 0\n");
814 return err;
815}
816
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100817const struct seq_operations mounts_op = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 .start = m_start,
819 .next = m_next,
820 .stop = m_stop,
821 .show = show_vfsmnt
822};
823
Ram Pai2d4d4862008-03-27 13:06:25 +0100824static int show_mountinfo(struct seq_file *m, void *v)
825{
826 struct proc_mounts *p = m->private;
827 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
828 struct super_block *sb = mnt->mnt_sb;
829 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
830 struct path root = p->root;
831 int err = 0;
832
833 seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
834 MAJOR(sb->s_dev), MINOR(sb->s_dev));
835 seq_dentry(m, mnt->mnt_root, " \t\n\\");
836 seq_putc(m, ' ');
837 seq_path_root(m, &mnt_path, &root, " \t\n\\");
838 if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
839 /*
840 * Mountpoint is outside root, discard that one. Ugly,
841 * but less so than trying to do that in iterator in a
842 * race-free way (due to renames).
843 */
844 return SEQ_SKIP;
845 }
846 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
847 show_mnt_opts(m, mnt);
848
849 /* Tagged fields ("foo:X" or "bar") */
850 if (IS_MNT_SHARED(mnt))
851 seq_printf(m, " shared:%i", mnt->mnt_group_id);
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +0100852 if (IS_MNT_SLAVE(mnt)) {
853 int master = mnt->mnt_master->mnt_group_id;
854 int dom = get_dominating_id(mnt, &p->root);
855 seq_printf(m, " master:%i", master);
856 if (dom && dom != master)
857 seq_printf(m, " propagate_from:%i", dom);
858 }
Ram Pai2d4d4862008-03-27 13:06:25 +0100859 if (IS_MNT_UNBINDABLE(mnt))
860 seq_puts(m, " unbindable");
861
862 /* Filesystem specific data */
863 seq_puts(m, " - ");
864 show_type(m, sb);
865 seq_putc(m, ' ');
866 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
867 seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
868 show_sb_opts(m, sb);
869 if (sb->s_op->show_options)
870 err = sb->s_op->show_options(m, mnt);
871 seq_putc(m, '\n');
872 return err;
873}
874
875const struct seq_operations mountinfo_op = {
876 .start = m_start,
877 .next = m_next,
878 .stop = m_stop,
879 .show = show_mountinfo,
880};
881
Chuck Leverb4629fe2006-03-20 13:44:12 -0500882static int show_vfsstat(struct seq_file *m, void *v)
883{
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700884 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
Jan Blunckc32c2f62008-02-14 19:38:43 -0800885 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
Chuck Leverb4629fe2006-03-20 13:44:12 -0500886 int err = 0;
887
888 /* device */
889 if (mnt->mnt_devname) {
890 seq_puts(m, "device ");
891 mangle(m, mnt->mnt_devname);
892 } else
893 seq_puts(m, "no device");
894
895 /* mount point */
896 seq_puts(m, " mounted on ");
Jan Blunckc32c2f62008-02-14 19:38:43 -0800897 seq_path(m, &mnt_path, " \t\n\\");
Chuck Leverb4629fe2006-03-20 13:44:12 -0500898 seq_putc(m, ' ');
899
900 /* file system type */
901 seq_puts(m, "with fstype ");
Ram Pai2d4d4862008-03-27 13:06:25 +0100902 show_type(m, mnt->mnt_sb);
Chuck Leverb4629fe2006-03-20 13:44:12 -0500903
904 /* optional statistics */
905 if (mnt->mnt_sb->s_op->show_stats) {
906 seq_putc(m, ' ');
907 err = mnt->mnt_sb->s_op->show_stats(m, mnt);
908 }
909
910 seq_putc(m, '\n');
911 return err;
912}
913
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100914const struct seq_operations mountstats_op = {
Chuck Leverb4629fe2006-03-20 13:44:12 -0500915 .start = m_start,
916 .next = m_next,
917 .stop = m_stop,
918 .show = show_vfsstat,
919};
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100920#endif /* CONFIG_PROC_FS */
Chuck Leverb4629fe2006-03-20 13:44:12 -0500921
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922/**
923 * may_umount_tree - check if a mount tree is busy
924 * @mnt: root of mount tree
925 *
926 * This is called to check if a tree of mounts has any
927 * open files, pwds, chroots or sub mounts that are
928 * busy.
929 */
930int may_umount_tree(struct vfsmount *mnt)
931{
Ram Pai36341f62005-11-07 17:17:22 -0500932 int actual_refs = 0;
933 int minimum_refs = 0;
934 struct vfsmount *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935
936 spin_lock(&vfsmount_lock);
Ram Pai36341f62005-11-07 17:17:22 -0500937 for (p = mnt; p; p = next_mnt(p, mnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938 actual_refs += atomic_read(&p->mnt_count);
939 minimum_refs += 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940 }
941 spin_unlock(&vfsmount_lock);
942
943 if (actual_refs > minimum_refs)
Ian Kente3474a82006-03-27 01:14:51 -0800944 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945
Ian Kente3474a82006-03-27 01:14:51 -0800946 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947}
948
949EXPORT_SYMBOL(may_umount_tree);
950
951/**
952 * may_umount - check if a mount point is busy
953 * @mnt: root of mount
954 *
955 * This is called to check if a mount point has any
956 * open files, pwds, chroots or sub mounts. If the
957 * mount has sub mounts this will return busy
958 * regardless of whether the sub mounts are busy.
959 *
960 * Doesn't take quota and stuff into account. IOW, in some cases it will
961 * give false negatives. The main reason why it's here is that we need
962 * a non-destructive way to look for easily umountable filesystems.
963 */
964int may_umount(struct vfsmount *mnt)
965{
Ian Kente3474a82006-03-27 01:14:51 -0800966 int ret = 1;
Ram Paia05964f2005-11-07 17:20:17 -0500967 spin_lock(&vfsmount_lock);
968 if (propagate_mount_busy(mnt, 2))
Ian Kente3474a82006-03-27 01:14:51 -0800969 ret = 0;
Ram Paia05964f2005-11-07 17:20:17 -0500970 spin_unlock(&vfsmount_lock);
971 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972}
973
974EXPORT_SYMBOL(may_umount);
975
Ram Paib90fa9a2005-11-07 17:19:50 -0500976void release_mounts(struct list_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977{
Ram Pai70fbcdf2005-11-07 17:17:04 -0500978 struct vfsmount *mnt;
Miklos Szeredibf066c72006-01-08 01:03:19 -0800979 while (!list_empty(head)) {
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700980 mnt = list_first_entry(head, struct vfsmount, mnt_hash);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500981 list_del_init(&mnt->mnt_hash);
982 if (mnt->mnt_parent != mnt) {
983 struct dentry *dentry;
984 struct vfsmount *m;
985 spin_lock(&vfsmount_lock);
986 dentry = mnt->mnt_mountpoint;
987 m = mnt->mnt_parent;
988 mnt->mnt_mountpoint = mnt->mnt_root;
989 mnt->mnt_parent = mnt;
Al Viro7c4b93d2008-03-21 23:59:49 -0400990 m->mnt_ghosts--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500992 dput(dentry);
993 mntput(m);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 }
995 mntput(mnt);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500996 }
997}
998
Ram Paia05964f2005-11-07 17:20:17 -0500999void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
Ram Pai70fbcdf2005-11-07 17:17:04 -05001000{
1001 struct vfsmount *p;
1002
Akinobu Mita1bfba4e2006-06-26 00:24:40 -07001003 for (p = mnt; p; p = next_mnt(p, mnt))
1004 list_move(&p->mnt_hash, kill);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001005
Ram Paia05964f2005-11-07 17:20:17 -05001006 if (propagate)
1007 propagate_umount(kill);
1008
Ram Pai70fbcdf2005-11-07 17:17:04 -05001009 list_for_each_entry(p, kill, mnt_hash) {
1010 list_del_init(&p->mnt_expire);
1011 list_del_init(&p->mnt_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001012 __touch_mnt_namespace(p->mnt_ns);
1013 p->mnt_ns = NULL;
Ram Pai70fbcdf2005-11-07 17:17:04 -05001014 list_del_init(&p->mnt_child);
Al Viro7c4b93d2008-03-21 23:59:49 -04001015 if (p->mnt_parent != p) {
1016 p->mnt_parent->mnt_ghosts++;
Al Virof30ac312006-02-01 07:53:21 -05001017 p->mnt_mountpoint->d_mounted--;
Al Viro7c4b93d2008-03-21 23:59:49 -04001018 }
Ram Paia05964f2005-11-07 17:20:17 -05001019 change_mnt_propagation(p, MS_PRIVATE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 }
1021}
1022
Al Viroc35038b2008-03-22 00:46:23 -04001023static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts);
1024
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025static int do_umount(struct vfsmount *mnt, int flags)
1026{
Ram Paib58fed82005-11-07 17:16:09 -05001027 struct super_block *sb = mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 int retval;
Ram Pai70fbcdf2005-11-07 17:17:04 -05001029 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030
1031 retval = security_sb_umount(mnt, flags);
1032 if (retval)
1033 return retval;
1034
1035 /*
1036 * Allow userspace to request a mountpoint be expired rather than
1037 * unmounting unconditionally. Unmount only happens if:
1038 * (1) the mark is already set (the mark is cleared by mntput())
1039 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
1040 */
1041 if (flags & MNT_EXPIRE) {
Jan Blunck6ac08c32008-02-14 19:34:38 -08001042 if (mnt == current->fs->root.mnt ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 flags & (MNT_FORCE | MNT_DETACH))
1044 return -EINVAL;
1045
1046 if (atomic_read(&mnt->mnt_count) != 2)
1047 return -EBUSY;
1048
1049 if (!xchg(&mnt->mnt_expiry_mark, 1))
1050 return -EAGAIN;
1051 }
1052
1053 /*
1054 * If we may have to abort operations to get out of this
1055 * mount, and they will themselves hold resources we must
1056 * allow the fs to do things. In the Unix tradition of
1057 * 'Gee thats tricky lets do it in userspace' the umount_begin
1058 * might fail to complete on the first run through as other tasks
1059 * must return, and the like. Thats for the mount program to worry
1060 * about for the moment.
1061 */
1062
Al Viro42faad92008-04-24 07:21:56 -04001063 if (flags & MNT_FORCE && sb->s_op->umount_begin) {
1064 lock_kernel();
1065 sb->s_op->umount_begin(sb);
1066 unlock_kernel();
1067 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068
1069 /*
1070 * No sense to grab the lock for this test, but test itself looks
1071 * somewhat bogus. Suggestions for better replacement?
1072 * Ho-hum... In principle, we might treat that as umount + switch
1073 * to rootfs. GC would eventually take care of the old vfsmount.
1074 * Actually it makes sense, especially if rootfs would contain a
1075 * /reboot - static binary that would close all descriptors and
1076 * call reboot(9). Then init(8) could umount root and exec /reboot.
1077 */
Jan Blunck6ac08c32008-02-14 19:34:38 -08001078 if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 /*
1080 * Special case for "unmounting" root ...
1081 * we just try to remount it readonly.
1082 */
1083 down_write(&sb->s_umount);
1084 if (!(sb->s_flags & MS_RDONLY)) {
1085 lock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086 retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
1087 unlock_kernel();
1088 }
1089 up_write(&sb->s_umount);
1090 return retval;
1091 }
1092
Ram Pai390c6842005-11-07 17:17:51 -05001093 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 spin_lock(&vfsmount_lock);
Al Viro5addc5d2005-11-07 17:15:49 -05001095 event++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096
Al Viroc35038b2008-03-22 00:46:23 -04001097 if (!(flags & MNT_DETACH))
1098 shrink_submounts(mnt, &umount_list);
1099
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100 retval = -EBUSY;
Ram Paia05964f2005-11-07 17:20:17 -05001101 if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 if (!list_empty(&mnt->mnt_list))
Ram Paia05964f2005-11-07 17:20:17 -05001103 umount_tree(mnt, 1, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104 retval = 0;
1105 }
1106 spin_unlock(&vfsmount_lock);
1107 if (retval)
1108 security_sb_umount_busy(mnt);
Ram Pai390c6842005-11-07 17:17:51 -05001109 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001110 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111 return retval;
1112}
1113
1114/*
1115 * Now umount can handle mount points as well as block devices.
1116 * This is important for filesystems which use unnamed block devices.
1117 *
1118 * We now support a flag for forced unmount like the other 'big iron'
1119 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
1120 */
1121
1122asmlinkage long sys_umount(char __user * name, int flags)
1123{
1124 struct nameidata nd;
1125 int retval;
1126
1127 retval = __user_walk(name, LOOKUP_FOLLOW, &nd);
1128 if (retval)
1129 goto out;
1130 retval = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -08001131 if (nd.path.dentry != nd.path.mnt->mnt_root)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132 goto dput_and_out;
Jan Blunck4ac91372008-02-14 19:34:32 -08001133 if (!check_mnt(nd.path.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 goto dput_and_out;
1135
1136 retval = -EPERM;
1137 if (!capable(CAP_SYS_ADMIN))
1138 goto dput_and_out;
1139
Jan Blunck4ac91372008-02-14 19:34:32 -08001140 retval = do_umount(nd.path.mnt, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141dput_and_out:
Jan Blunck429731b2008-02-14 19:34:31 -08001142 /* we mustn't call path_put() as that would clear mnt_expiry_mark */
Jan Blunck4ac91372008-02-14 19:34:32 -08001143 dput(nd.path.dentry);
1144 mntput_no_expire(nd.path.mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145out:
1146 return retval;
1147}
1148
1149#ifdef __ARCH_WANT_SYS_OLDUMOUNT
1150
1151/*
Ram Paib58fed82005-11-07 17:16:09 -05001152 * The 2.0 compatible umount. No flags.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154asmlinkage long sys_oldumount(char __user * name)
1155{
Ram Paib58fed82005-11-07 17:16:09 -05001156 return sys_umount(name, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157}
1158
1159#endif
1160
1161static int mount_is_safe(struct nameidata *nd)
1162{
1163 if (capable(CAP_SYS_ADMIN))
1164 return 0;
1165 return -EPERM;
1166#ifdef notyet
Jan Blunck4ac91372008-02-14 19:34:32 -08001167 if (S_ISLNK(nd->path.dentry->d_inode->i_mode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168 return -EPERM;
Jan Blunck4ac91372008-02-14 19:34:32 -08001169 if (nd->path.dentry->d_inode->i_mode & S_ISVTX) {
1170 if (current->uid != nd->path.dentry->d_inode->i_uid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 return -EPERM;
1172 }
Christoph Hellwige4543ed2005-11-08 21:35:04 -08001173 if (vfs_permission(nd, MAY_WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 return -EPERM;
1175 return 0;
1176#endif
1177}
1178
Ram Paib58fed82005-11-07 17:16:09 -05001179static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180{
1181 while (1) {
1182 if (d == dentry)
1183 return 1;
1184 if (d == NULL || d == d->d_parent)
1185 return 0;
1186 d = d->d_parent;
1187 }
1188}
1189
Ram Paib90fa9a2005-11-07 17:19:50 -05001190struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
Ram Pai36341f62005-11-07 17:17:22 -05001191 int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192{
1193 struct vfsmount *res, *p, *q, *r, *s;
Al Viro1a390682008-03-21 20:48:19 -04001194 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195
Ram Pai9676f0c2005-11-07 17:21:20 -05001196 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
1197 return NULL;
1198
Ram Pai36341f62005-11-07 17:17:22 -05001199 res = q = clone_mnt(mnt, dentry, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 if (!q)
1201 goto Enomem;
1202 q->mnt_mountpoint = mnt->mnt_mountpoint;
1203
1204 p = mnt;
Domen Puncerfdadd652005-09-10 00:27:07 -07001205 list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry))
1207 continue;
1208
1209 for (s = r; s; s = next_mnt(s, r)) {
Ram Pai9676f0c2005-11-07 17:21:20 -05001210 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
1211 s = skip_mnt_tree(s);
1212 continue;
1213 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 while (p != s->mnt_parent) {
1215 p = p->mnt_parent;
1216 q = q->mnt_parent;
1217 }
1218 p = s;
Al Viro1a390682008-03-21 20:48:19 -04001219 path.mnt = q;
1220 path.dentry = p->mnt_mountpoint;
Ram Pai36341f62005-11-07 17:17:22 -05001221 q = clone_mnt(p, p->mnt_root, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 if (!q)
1223 goto Enomem;
1224 spin_lock(&vfsmount_lock);
1225 list_add_tail(&q->mnt_list, &res->mnt_list);
Al Viro1a390682008-03-21 20:48:19 -04001226 attach_mnt(q, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227 spin_unlock(&vfsmount_lock);
1228 }
1229 }
1230 return res;
Ram Paib58fed82005-11-07 17:16:09 -05001231Enomem:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232 if (res) {
Ram Pai70fbcdf2005-11-07 17:17:04 -05001233 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05001235 umount_tree(res, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001237 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 }
1239 return NULL;
1240}
1241
Al Viro8aec0802007-06-07 12:20:32 -04001242struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)
1243{
1244 struct vfsmount *tree;
Al Viro1a60a282008-03-22 16:19:49 -04001245 down_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001246 tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE);
Al Viro1a60a282008-03-22 16:19:49 -04001247 up_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001248 return tree;
1249}
1250
1251void drop_collected_mounts(struct vfsmount *mnt)
1252{
1253 LIST_HEAD(umount_list);
Al Viro1a60a282008-03-22 16:19:49 -04001254 down_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001255 spin_lock(&vfsmount_lock);
1256 umount_tree(mnt, 0, &umount_list);
1257 spin_unlock(&vfsmount_lock);
Al Viro1a60a282008-03-22 16:19:49 -04001258 up_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001259 release_mounts(&umount_list);
1260}
1261
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001262static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end)
1263{
1264 struct vfsmount *p;
1265
1266 for (p = mnt; p != end; p = next_mnt(p, mnt)) {
1267 if (p->mnt_group_id && !IS_MNT_SHARED(p))
1268 mnt_release_group_id(p);
1269 }
1270}
1271
1272static int invent_group_ids(struct vfsmount *mnt, bool recurse)
1273{
1274 struct vfsmount *p;
1275
1276 for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) {
1277 if (!p->mnt_group_id && !IS_MNT_SHARED(p)) {
1278 int err = mnt_alloc_group_id(p);
1279 if (err) {
1280 cleanup_group_ids(mnt, p);
1281 return err;
1282 }
1283 }
1284 }
1285
1286 return 0;
1287}
1288
Ram Paib90fa9a2005-11-07 17:19:50 -05001289/*
1290 * @source_mnt : mount tree to be attached
Ram Pai21444402005-11-07 17:20:03 -05001291 * @nd : place the mount tree @source_mnt is attached
1292 * @parent_nd : if non-null, detach the source_mnt from its parent and
1293 * store the parent mount and mountpoint dentry.
1294 * (done when source_mnt is moved)
Ram Paib90fa9a2005-11-07 17:19:50 -05001295 *
1296 * NOTE: in the table below explains the semantics when a source mount
1297 * of a given type is attached to a destination mount of a given type.
Ram Pai9676f0c2005-11-07 17:21:20 -05001298 * ---------------------------------------------------------------------------
1299 * | BIND MOUNT OPERATION |
1300 * |**************************************************************************
1301 * | source-->| shared | private | slave | unbindable |
1302 * | dest | | | | |
1303 * | | | | | | |
1304 * | v | | | | |
1305 * |**************************************************************************
1306 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
1307 * | | | | | |
1308 * |non-shared| shared (+) | private | slave (*) | invalid |
1309 * ***************************************************************************
Ram Paib90fa9a2005-11-07 17:19:50 -05001310 * A bind operation clones the source mount and mounts the clone on the
1311 * destination mount.
1312 *
1313 * (++) the cloned mount is propagated to all the mounts in the propagation
1314 * tree of the destination mount and the cloned mount is added to
1315 * the peer group of the source mount.
1316 * (+) the cloned mount is created under the destination mount and is marked
1317 * as shared. The cloned mount is added to the peer group of the source
1318 * mount.
Ram Pai5afe0022005-11-07 17:21:01 -05001319 * (+++) the mount is propagated to all the mounts in the propagation tree
1320 * of the destination mount and the cloned mount is made slave
1321 * of the same master as that of the source mount. The cloned mount
1322 * is marked as 'shared and slave'.
1323 * (*) the cloned mount is made a slave of the same master as that of the
1324 * source mount.
1325 *
Ram Pai9676f0c2005-11-07 17:21:20 -05001326 * ---------------------------------------------------------------------------
1327 * | MOVE MOUNT OPERATION |
1328 * |**************************************************************************
1329 * | source-->| shared | private | slave | unbindable |
1330 * | dest | | | | |
1331 * | | | | | | |
1332 * | v | | | | |
1333 * |**************************************************************************
1334 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
1335 * | | | | | |
1336 * |non-shared| shared (+*) | private | slave (*) | unbindable |
1337 * ***************************************************************************
Ram Pai5afe0022005-11-07 17:21:01 -05001338 *
1339 * (+) the mount is moved to the destination. And is then propagated to
1340 * all the mounts in the propagation tree of the destination mount.
Ram Pai21444402005-11-07 17:20:03 -05001341 * (+*) the mount is moved to the destination.
Ram Pai5afe0022005-11-07 17:21:01 -05001342 * (+++) the mount is moved to the destination and is then propagated to
1343 * all the mounts belonging to the destination mount's propagation tree.
1344 * the mount is marked as 'shared and slave'.
1345 * (*) the mount continues to be a slave at the new location.
Ram Paib90fa9a2005-11-07 17:19:50 -05001346 *
1347 * if the source mount is a tree, the operations explained above is
1348 * applied to each mount in the tree.
1349 * Must be called without spinlocks held, since this function can sleep
1350 * in allocations.
1351 */
1352static int attach_recursive_mnt(struct vfsmount *source_mnt,
Al Viro1a390682008-03-21 20:48:19 -04001353 struct path *path, struct path *parent_path)
Ram Paib90fa9a2005-11-07 17:19:50 -05001354{
1355 LIST_HEAD(tree_list);
Al Viro1a390682008-03-21 20:48:19 -04001356 struct vfsmount *dest_mnt = path->mnt;
1357 struct dentry *dest_dentry = path->dentry;
Ram Paib90fa9a2005-11-07 17:19:50 -05001358 struct vfsmount *child, *p;
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001359 int err;
Ram Paib90fa9a2005-11-07 17:19:50 -05001360
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001361 if (IS_MNT_SHARED(dest_mnt)) {
1362 err = invent_group_ids(source_mnt, true);
1363 if (err)
1364 goto out;
1365 }
1366 err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list);
1367 if (err)
1368 goto out_cleanup_ids;
Ram Paib90fa9a2005-11-07 17:19:50 -05001369
1370 if (IS_MNT_SHARED(dest_mnt)) {
1371 for (p = source_mnt; p; p = next_mnt(p, source_mnt))
1372 set_mnt_shared(p);
1373 }
1374
1375 spin_lock(&vfsmount_lock);
Al Viro1a390682008-03-21 20:48:19 -04001376 if (parent_path) {
1377 detach_mnt(source_mnt, parent_path);
1378 attach_mnt(source_mnt, path);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001379 touch_mnt_namespace(current->nsproxy->mnt_ns);
Ram Pai21444402005-11-07 17:20:03 -05001380 } else {
1381 mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
1382 commit_tree(source_mnt);
1383 }
Ram Paib90fa9a2005-11-07 17:19:50 -05001384
1385 list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
1386 list_del_init(&child->mnt_hash);
1387 commit_tree(child);
1388 }
1389 spin_unlock(&vfsmount_lock);
1390 return 0;
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001391
1392 out_cleanup_ids:
1393 if (IS_MNT_SHARED(dest_mnt))
1394 cleanup_group_ids(source_mnt, NULL);
1395 out:
1396 return err;
Ram Paib90fa9a2005-11-07 17:19:50 -05001397}
1398
Al Viro8c3ee422008-03-22 18:00:39 -04001399static int graft_tree(struct vfsmount *mnt, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400{
1401 int err;
1402 if (mnt->mnt_sb->s_flags & MS_NOUSER)
1403 return -EINVAL;
1404
Al Viro8c3ee422008-03-22 18:00:39 -04001405 if (S_ISDIR(path->dentry->d_inode->i_mode) !=
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 S_ISDIR(mnt->mnt_root->d_inode->i_mode))
1407 return -ENOTDIR;
1408
1409 err = -ENOENT;
Al Viro8c3ee422008-03-22 18:00:39 -04001410 mutex_lock(&path->dentry->d_inode->i_mutex);
1411 if (IS_DEADDIR(path->dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 goto out_unlock;
1413
Al Viro8c3ee422008-03-22 18:00:39 -04001414 err = security_sb_check_sb(mnt, path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 if (err)
1416 goto out_unlock;
1417
1418 err = -ENOENT;
Al Viro8c3ee422008-03-22 18:00:39 -04001419 if (IS_ROOT(path->dentry) || !d_unhashed(path->dentry))
1420 err = attach_recursive_mnt(mnt, path, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421out_unlock:
Al Viro8c3ee422008-03-22 18:00:39 -04001422 mutex_unlock(&path->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 if (!err)
Al Viro8c3ee422008-03-22 18:00:39 -04001424 security_sb_post_addmount(mnt, path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 return err;
1426}
1427
1428/*
Ram Pai07b20882005-11-07 17:19:07 -05001429 * recursively change the type of the mountpoint.
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001430 * noinline this do_mount helper to save do_mount stack space.
Ram Pai07b20882005-11-07 17:19:07 -05001431 */
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001432static noinline int do_change_type(struct nameidata *nd, int flag)
Ram Pai07b20882005-11-07 17:19:07 -05001433{
Jan Blunck4ac91372008-02-14 19:34:32 -08001434 struct vfsmount *m, *mnt = nd->path.mnt;
Ram Pai07b20882005-11-07 17:19:07 -05001435 int recurse = flag & MS_REC;
1436 int type = flag & ~MS_REC;
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001437 int err = 0;
Ram Pai07b20882005-11-07 17:19:07 -05001438
Miklos Szerediee6f9582007-05-08 00:30:40 -07001439 if (!capable(CAP_SYS_ADMIN))
1440 return -EPERM;
1441
Jan Blunck4ac91372008-02-14 19:34:32 -08001442 if (nd->path.dentry != nd->path.mnt->mnt_root)
Ram Pai07b20882005-11-07 17:19:07 -05001443 return -EINVAL;
1444
1445 down_write(&namespace_sem);
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001446 if (type == MS_SHARED) {
1447 err = invent_group_ids(mnt, recurse);
1448 if (err)
1449 goto out_unlock;
1450 }
1451
Ram Pai07b20882005-11-07 17:19:07 -05001452 spin_lock(&vfsmount_lock);
1453 for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
1454 change_mnt_propagation(m, type);
1455 spin_unlock(&vfsmount_lock);
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001456
1457 out_unlock:
Ram Pai07b20882005-11-07 17:19:07 -05001458 up_write(&namespace_sem);
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001459 return err;
Ram Pai07b20882005-11-07 17:19:07 -05001460}
1461
1462/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 * do loopback mount.
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001464 * noinline this do_mount helper to save do_mount stack space.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 */
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001466static noinline int do_loopback(struct nameidata *nd, char *old_name,
1467 int recurse)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468{
1469 struct nameidata old_nd;
1470 struct vfsmount *mnt = NULL;
1471 int err = mount_is_safe(nd);
1472 if (err)
1473 return err;
1474 if (!old_name || !*old_name)
1475 return -EINVAL;
1476 err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
1477 if (err)
1478 return err;
1479
Ram Pai390c6842005-11-07 17:17:51 -05001480 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 err = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -08001482 if (IS_MNT_UNBINDABLE(old_nd.path.mnt))
1483 goto out;
Ram Pai9676f0c2005-11-07 17:21:20 -05001484
Jan Blunck4ac91372008-02-14 19:34:32 -08001485 if (!check_mnt(nd->path.mnt) || !check_mnt(old_nd.path.mnt))
Al Viroccd48bc2005-11-07 17:15:04 -05001486 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487
Al Viroccd48bc2005-11-07 17:15:04 -05001488 err = -ENOMEM;
1489 if (recurse)
Jan Blunck4ac91372008-02-14 19:34:32 -08001490 mnt = copy_tree(old_nd.path.mnt, old_nd.path.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -05001491 else
Jan Blunck4ac91372008-02-14 19:34:32 -08001492 mnt = clone_mnt(old_nd.path.mnt, old_nd.path.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -05001493
1494 if (!mnt)
1495 goto out;
1496
Al Viro8c3ee422008-03-22 18:00:39 -04001497 err = graft_tree(mnt, &nd->path);
Al Viroccd48bc2005-11-07 17:15:04 -05001498 if (err) {
Ram Pai70fbcdf2005-11-07 17:17:04 -05001499 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05001501 umount_tree(mnt, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001503 release_mounts(&umount_list);
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001504 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505
Al Viroccd48bc2005-11-07 17:15:04 -05001506out:
Ram Pai390c6842005-11-07 17:17:51 -05001507 up_write(&namespace_sem);
Jan Blunck1d957f92008-02-14 19:34:35 -08001508 path_put(&old_nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 return err;
1510}
1511
Dave Hansen2e4b7fc2008-02-15 14:38:00 -08001512static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
1513{
1514 int error = 0;
1515 int readonly_request = 0;
1516
1517 if (ms_flags & MS_RDONLY)
1518 readonly_request = 1;
1519 if (readonly_request == __mnt_is_readonly(mnt))
1520 return 0;
1521
1522 if (readonly_request)
1523 error = mnt_make_readonly(mnt);
1524 else
1525 __mnt_unmake_readonly(mnt);
1526 return error;
1527}
1528
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529/*
1530 * change filesystem flags. dir should be a physical root of filesystem.
1531 * If you've mounted a non-root directory somewhere and want to do remount
1532 * on it - tough luck.
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001533 * noinline this do_mount helper to save do_mount stack space.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534 */
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001535static noinline int do_remount(struct nameidata *nd, int flags, int mnt_flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 void *data)
1537{
1538 int err;
Jan Blunck4ac91372008-02-14 19:34:32 -08001539 struct super_block *sb = nd->path.mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540
1541 if (!capable(CAP_SYS_ADMIN))
1542 return -EPERM;
1543
Jan Blunck4ac91372008-02-14 19:34:32 -08001544 if (!check_mnt(nd->path.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 return -EINVAL;
1546
Jan Blunck4ac91372008-02-14 19:34:32 -08001547 if (nd->path.dentry != nd->path.mnt->mnt_root)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 return -EINVAL;
1549
1550 down_write(&sb->s_umount);
Dave Hansen2e4b7fc2008-02-15 14:38:00 -08001551 if (flags & MS_BIND)
1552 err = change_mount_flags(nd->path.mnt, flags);
1553 else
1554 err = do_remount_sb(sb, flags, data, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 if (!err)
Jan Blunck4ac91372008-02-14 19:34:32 -08001556 nd->path.mnt->mnt_flags = mnt_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 up_write(&sb->s_umount);
1558 if (!err)
Jan Blunck4ac91372008-02-14 19:34:32 -08001559 security_sb_post_remount(nd->path.mnt, flags, data);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 return err;
1561}
1562
Ram Pai9676f0c2005-11-07 17:21:20 -05001563static inline int tree_contains_unbindable(struct vfsmount *mnt)
1564{
1565 struct vfsmount *p;
1566 for (p = mnt; p; p = next_mnt(p, mnt)) {
1567 if (IS_MNT_UNBINDABLE(p))
1568 return 1;
1569 }
1570 return 0;
1571}
1572
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001573/*
1574 * noinline this do_mount helper to save do_mount stack space.
1575 */
1576static noinline int do_move_mount(struct nameidata *nd, char *old_name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577{
Al Viro1a390682008-03-21 20:48:19 -04001578 struct nameidata old_nd;
1579 struct path parent_path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580 struct vfsmount *p;
1581 int err = 0;
1582 if (!capable(CAP_SYS_ADMIN))
1583 return -EPERM;
1584 if (!old_name || !*old_name)
1585 return -EINVAL;
1586 err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
1587 if (err)
1588 return err;
1589
Ram Pai390c6842005-11-07 17:17:51 -05001590 down_write(&namespace_sem);
Jan Blunck4ac91372008-02-14 19:34:32 -08001591 while (d_mountpoint(nd->path.dentry) &&
1592 follow_down(&nd->path.mnt, &nd->path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 ;
1594 err = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -08001595 if (!check_mnt(nd->path.mnt) || !check_mnt(old_nd.path.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 goto out;
1597
1598 err = -ENOENT;
Jan Blunck4ac91372008-02-14 19:34:32 -08001599 mutex_lock(&nd->path.dentry->d_inode->i_mutex);
1600 if (IS_DEADDIR(nd->path.dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601 goto out1;
1602
Jan Blunck4ac91372008-02-14 19:34:32 -08001603 if (!IS_ROOT(nd->path.dentry) && d_unhashed(nd->path.dentry))
Ram Pai21444402005-11-07 17:20:03 -05001604 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605
1606 err = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -08001607 if (old_nd.path.dentry != old_nd.path.mnt->mnt_root)
Ram Pai21444402005-11-07 17:20:03 -05001608 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609
Jan Blunck4ac91372008-02-14 19:34:32 -08001610 if (old_nd.path.mnt == old_nd.path.mnt->mnt_parent)
Ram Pai21444402005-11-07 17:20:03 -05001611 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612
Jan Blunck4ac91372008-02-14 19:34:32 -08001613 if (S_ISDIR(nd->path.dentry->d_inode->i_mode) !=
1614 S_ISDIR(old_nd.path.dentry->d_inode->i_mode))
Ram Pai21444402005-11-07 17:20:03 -05001615 goto out1;
1616 /*
1617 * Don't move a mount residing in a shared parent.
1618 */
Jan Blunck4ac91372008-02-14 19:34:32 -08001619 if (old_nd.path.mnt->mnt_parent &&
1620 IS_MNT_SHARED(old_nd.path.mnt->mnt_parent))
Ram Pai21444402005-11-07 17:20:03 -05001621 goto out1;
Ram Pai9676f0c2005-11-07 17:21:20 -05001622 /*
1623 * Don't move a mount tree containing unbindable mounts to a destination
1624 * mount which is shared.
1625 */
Jan Blunck4ac91372008-02-14 19:34:32 -08001626 if (IS_MNT_SHARED(nd->path.mnt) &&
1627 tree_contains_unbindable(old_nd.path.mnt))
Ram Pai9676f0c2005-11-07 17:21:20 -05001628 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 err = -ELOOP;
Jan Blunck4ac91372008-02-14 19:34:32 -08001630 for (p = nd->path.mnt; p->mnt_parent != p; p = p->mnt_parent)
1631 if (p == old_nd.path.mnt)
Ram Pai21444402005-11-07 17:20:03 -05001632 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633
Al Viro1a390682008-03-21 20:48:19 -04001634 err = attach_recursive_mnt(old_nd.path.mnt, &nd->path, &parent_path);
Jan Blunck4ac91372008-02-14 19:34:32 -08001635 if (err)
Ram Pai21444402005-11-07 17:20:03 -05001636 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637
1638 /* if the mount is moved, it should no longer be expire
1639 * automatically */
Jan Blunck4ac91372008-02-14 19:34:32 -08001640 list_del_init(&old_nd.path.mnt->mnt_expire);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641out1:
Jan Blunck4ac91372008-02-14 19:34:32 -08001642 mutex_unlock(&nd->path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001643out:
Ram Pai390c6842005-11-07 17:17:51 -05001644 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 if (!err)
Al Viro1a390682008-03-21 20:48:19 -04001646 path_put(&parent_path);
Jan Blunck1d957f92008-02-14 19:34:35 -08001647 path_put(&old_nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648 return err;
1649}
1650
1651/*
1652 * create a new mount for userspace and request it to be added into the
1653 * namespace's tree
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001654 * noinline this do_mount helper to save do_mount stack space.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 */
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001656static noinline int do_new_mount(struct nameidata *nd, char *type, int flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001657 int mnt_flags, char *name, void *data)
1658{
1659 struct vfsmount *mnt;
1660
1661 if (!type || !memchr(type, 0, PAGE_SIZE))
1662 return -EINVAL;
1663
1664 /* we need capabilities... */
1665 if (!capable(CAP_SYS_ADMIN))
1666 return -EPERM;
1667
1668 mnt = do_kern_mount(type, flags, name, data);
1669 if (IS_ERR(mnt))
1670 return PTR_ERR(mnt);
1671
1672 return do_add_mount(mnt, nd, mnt_flags, NULL);
1673}
1674
1675/*
1676 * add a mount into a namespace's mount tree
1677 * - provide the option of adding the new mount to an expiration list
1678 */
1679int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
1680 int mnt_flags, struct list_head *fslist)
1681{
1682 int err;
1683
Ram Pai390c6842005-11-07 17:17:51 -05001684 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 /* Something was mounted here while we slept */
Jan Blunck4ac91372008-02-14 19:34:32 -08001686 while (d_mountpoint(nd->path.dentry) &&
1687 follow_down(&nd->path.mnt, &nd->path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688 ;
1689 err = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -08001690 if (!check_mnt(nd->path.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001691 goto unlock;
1692
1693 /* Refuse the same filesystem on the same mount point */
1694 err = -EBUSY;
Jan Blunck4ac91372008-02-14 19:34:32 -08001695 if (nd->path.mnt->mnt_sb == newmnt->mnt_sb &&
1696 nd->path.mnt->mnt_root == nd->path.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 goto unlock;
1698
1699 err = -EINVAL;
1700 if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
1701 goto unlock;
1702
1703 newmnt->mnt_flags = mnt_flags;
Al Viro8c3ee422008-03-22 18:00:39 -04001704 if ((err = graft_tree(newmnt, &nd->path)))
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001705 goto unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706
Al Viro6758f952008-03-22 16:14:30 -04001707 if (fslist) /* add to the specified expiration list */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001708 list_add_tail(&newmnt->mnt_expire, fslist);
Al Viro6758f952008-03-22 16:14:30 -04001709
Ram Pai390c6842005-11-07 17:17:51 -05001710 up_write(&namespace_sem);
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001711 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712
1713unlock:
Ram Pai390c6842005-11-07 17:17:51 -05001714 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 mntput(newmnt);
1716 return err;
1717}
1718
1719EXPORT_SYMBOL_GPL(do_add_mount);
1720
Trond Myklebust5528f9112006-06-09 09:34:17 -04001721/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 * process a list of expirable mountpoints with the intent of discarding any
1723 * mountpoints that aren't in use and haven't been touched since last we came
1724 * here
1725 */
1726void mark_mounts_for_expiry(struct list_head *mounts)
1727{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728 struct vfsmount *mnt, *next;
1729 LIST_HEAD(graveyard);
Al Virobcc5c7d2008-03-22 00:21:53 -04001730 LIST_HEAD(umounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731
1732 if (list_empty(mounts))
1733 return;
1734
Al Virobcc5c7d2008-03-22 00:21:53 -04001735 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 spin_lock(&vfsmount_lock);
1737
1738 /* extract from the expiration list every vfsmount that matches the
1739 * following criteria:
1740 * - only referenced by its parent vfsmount
1741 * - still marked for expiry (marked on the last call here; marks are
1742 * cleared by mntput())
1743 */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001744 list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 if (!xchg(&mnt->mnt_expiry_mark, 1) ||
Al Virobcc5c7d2008-03-22 00:21:53 -04001746 propagate_mount_busy(mnt, 1))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 continue;
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001748 list_move(&mnt->mnt_expire, &graveyard);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001749 }
Al Virobcc5c7d2008-03-22 00:21:53 -04001750 while (!list_empty(&graveyard)) {
1751 mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire);
1752 touch_mnt_namespace(mnt->mnt_ns);
1753 umount_tree(mnt, 1, &umounts);
1754 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 spin_unlock(&vfsmount_lock);
Al Virobcc5c7d2008-03-22 00:21:53 -04001756 up_write(&namespace_sem);
1757
1758 release_mounts(&umounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759}
1760
1761EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
1762
1763/*
Trond Myklebust5528f9112006-06-09 09:34:17 -04001764 * Ripoff of 'select_parent()'
1765 *
1766 * search the list of submounts for a given mountpoint, and move any
1767 * shrinkable submounts to the 'graveyard' list.
1768 */
1769static int select_submounts(struct vfsmount *parent, struct list_head *graveyard)
1770{
1771 struct vfsmount *this_parent = parent;
1772 struct list_head *next;
1773 int found = 0;
1774
1775repeat:
1776 next = this_parent->mnt_mounts.next;
1777resume:
1778 while (next != &this_parent->mnt_mounts) {
1779 struct list_head *tmp = next;
1780 struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child);
1781
1782 next = tmp->next;
1783 if (!(mnt->mnt_flags & MNT_SHRINKABLE))
1784 continue;
1785 /*
1786 * Descend a level if the d_mounts list is non-empty.
1787 */
1788 if (!list_empty(&mnt->mnt_mounts)) {
1789 this_parent = mnt;
1790 goto repeat;
1791 }
1792
1793 if (!propagate_mount_busy(mnt, 1)) {
Trond Myklebust5528f9112006-06-09 09:34:17 -04001794 list_move_tail(&mnt->mnt_expire, graveyard);
1795 found++;
1796 }
1797 }
1798 /*
1799 * All done at this level ... ascend and resume the search
1800 */
1801 if (this_parent != parent) {
1802 next = this_parent->mnt_child.next;
1803 this_parent = this_parent->mnt_parent;
1804 goto resume;
1805 }
1806 return found;
1807}
1808
1809/*
1810 * process a list of expirable mountpoints with the intent of discarding any
1811 * submounts of a specific parent mountpoint
1812 */
Al Viroc35038b2008-03-22 00:46:23 -04001813static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts)
Trond Myklebust5528f9112006-06-09 09:34:17 -04001814{
1815 LIST_HEAD(graveyard);
Al Viroc35038b2008-03-22 00:46:23 -04001816 struct vfsmount *m;
Trond Myklebust5528f9112006-06-09 09:34:17 -04001817
Trond Myklebust5528f9112006-06-09 09:34:17 -04001818 /* extract submounts of 'mountpoint' from the expiration list */
Al Viroc35038b2008-03-22 00:46:23 -04001819 while (select_submounts(mnt, &graveyard)) {
Al Virobcc5c7d2008-03-22 00:21:53 -04001820 while (!list_empty(&graveyard)) {
Al Viroc35038b2008-03-22 00:46:23 -04001821 m = list_first_entry(&graveyard, struct vfsmount,
Al Virobcc5c7d2008-03-22 00:21:53 -04001822 mnt_expire);
1823 touch_mnt_namespace(mnt->mnt_ns);
Al Viroc35038b2008-03-22 00:46:23 -04001824 umount_tree(mnt, 1, umounts);
Al Virobcc5c7d2008-03-22 00:21:53 -04001825 }
1826 }
Trond Myklebust5528f9112006-06-09 09:34:17 -04001827}
1828
Trond Myklebust5528f9112006-06-09 09:34:17 -04001829/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 * Some copy_from_user() implementations do not return the exact number of
1831 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
1832 * Note that this function differs from copy_from_user() in that it will oops
1833 * on bad values of `to', rather than returning a short copy.
1834 */
Ram Paib58fed82005-11-07 17:16:09 -05001835static long exact_copy_from_user(void *to, const void __user * from,
1836 unsigned long n)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837{
1838 char *t = to;
1839 const char __user *f = from;
1840 char c;
1841
1842 if (!access_ok(VERIFY_READ, from, n))
1843 return n;
1844
1845 while (n) {
1846 if (__get_user(c, f)) {
1847 memset(t, 0, n);
1848 break;
1849 }
1850 *t++ = c;
1851 f++;
1852 n--;
1853 }
1854 return n;
1855}
1856
Ram Paib58fed82005-11-07 17:16:09 -05001857int copy_mount_options(const void __user * data, unsigned long *where)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858{
1859 int i;
1860 unsigned long page;
1861 unsigned long size;
Ram Paib58fed82005-11-07 17:16:09 -05001862
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 *where = 0;
1864 if (!data)
1865 return 0;
1866
1867 if (!(page = __get_free_page(GFP_KERNEL)))
1868 return -ENOMEM;
1869
1870 /* We only care that *some* data at the address the user
1871 * gave us is valid. Just in case, we'll zero
1872 * the remainder of the page.
1873 */
1874 /* copy_from_user cannot cross TASK_SIZE ! */
1875 size = TASK_SIZE - (unsigned long)data;
1876 if (size > PAGE_SIZE)
1877 size = PAGE_SIZE;
1878
1879 i = size - exact_copy_from_user((void *)page, data, size);
1880 if (!i) {
Ram Paib58fed82005-11-07 17:16:09 -05001881 free_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 return -EFAULT;
1883 }
1884 if (i != PAGE_SIZE)
1885 memset((char *)page + i, 0, PAGE_SIZE - i);
1886 *where = page;
1887 return 0;
1888}
1889
1890/*
1891 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
1892 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
1893 *
1894 * data is a (void *) that can point to any structure up to
1895 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
1896 * information (or be NULL).
1897 *
1898 * Pre-0.97 versions of mount() didn't have a flags word.
1899 * When the flags word was introduced its top half was required
1900 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
1901 * Therefore, if this magic number is present, it carries no information
1902 * and must be discarded.
1903 */
Ram Paib58fed82005-11-07 17:16:09 -05001904long do_mount(char *dev_name, char *dir_name, char *type_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905 unsigned long flags, void *data_page)
1906{
1907 struct nameidata nd;
1908 int retval = 0;
1909 int mnt_flags = 0;
1910
1911 /* Discard magic */
1912 if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
1913 flags &= ~MS_MGC_MSK;
1914
1915 /* Basic sanity checks */
1916
1917 if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
1918 return -EINVAL;
1919 if (dev_name && !memchr(dev_name, 0, PAGE_SIZE))
1920 return -EINVAL;
1921
1922 if (data_page)
1923 ((char *)data_page)[PAGE_SIZE - 1] = 0;
1924
1925 /* Separate the per-mountpoint flags */
1926 if (flags & MS_NOSUID)
1927 mnt_flags |= MNT_NOSUID;
1928 if (flags & MS_NODEV)
1929 mnt_flags |= MNT_NODEV;
1930 if (flags & MS_NOEXEC)
1931 mnt_flags |= MNT_NOEXEC;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001932 if (flags & MS_NOATIME)
1933 mnt_flags |= MNT_NOATIME;
1934 if (flags & MS_NODIRATIME)
1935 mnt_flags |= MNT_NODIRATIME;
Valerie Henson47ae32d2006-12-13 00:34:34 -08001936 if (flags & MS_RELATIME)
1937 mnt_flags |= MNT_RELATIME;
Dave Hansen2e4b7fc2008-02-15 14:38:00 -08001938 if (flags & MS_RDONLY)
1939 mnt_flags |= MNT_READONLY;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001940
1941 flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001942 MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943
1944 /* ... and get the mountpoint */
1945 retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
1946 if (retval)
1947 return retval;
1948
Al Virob5266eb2008-03-22 17:48:24 -04001949 retval = security_sb_mount(dev_name, &nd.path,
1950 type_page, flags, data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 if (retval)
1952 goto dput_out;
1953
1954 if (flags & MS_REMOUNT)
1955 retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,
1956 data_page);
1957 else if (flags & MS_BIND)
Andrew Mortoneee391a2006-05-15 09:44:30 -07001958 retval = do_loopback(&nd, dev_name, flags & MS_REC);
Ram Pai9676f0c2005-11-07 17:21:20 -05001959 else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
Ram Pai07b20882005-11-07 17:19:07 -05001960 retval = do_change_type(&nd, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 else if (flags & MS_MOVE)
1962 retval = do_move_mount(&nd, dev_name);
1963 else
1964 retval = do_new_mount(&nd, type_page, flags, mnt_flags,
1965 dev_name, data_page);
1966dput_out:
Jan Blunck1d957f92008-02-14 19:34:35 -08001967 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 return retval;
1969}
1970
JANAK DESAI741a2952006-02-07 12:59:00 -08001971/*
1972 * Allocate a new namespace structure and populate it with contents
1973 * copied from the namespace of the passed in task structure.
1974 */
Badari Pulavartye3222c42007-05-08 00:25:21 -07001975static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001976 struct fs_struct *fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001978 struct mnt_namespace *new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980 struct vfsmount *p, *q;
1981
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001982 new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001983 if (!new_ns)
Cedric Le Goater467e9f42007-07-15 23:41:06 -07001984 return ERR_PTR(-ENOMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985
1986 atomic_set(&new_ns->count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987 INIT_LIST_HEAD(&new_ns->list);
Al Viro5addc5d2005-11-07 17:15:49 -05001988 init_waitqueue_head(&new_ns->poll);
1989 new_ns->event = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990
Ram Pai390c6842005-11-07 17:17:51 -05001991 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001992 /* First pass: copy the tree topology */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001993 new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root,
Ram Pai9676f0c2005-11-07 17:21:20 -05001994 CL_COPY_ALL | CL_EXPIRE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995 if (!new_ns->root) {
Ram Pai390c6842005-11-07 17:17:51 -05001996 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997 kfree(new_ns);
Cedric Le Goater467e9f42007-07-15 23:41:06 -07001998 return ERR_PTR(-ENOMEM);;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 }
2000 spin_lock(&vfsmount_lock);
2001 list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
2002 spin_unlock(&vfsmount_lock);
2003
2004 /*
2005 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
2006 * as belonging to new namespace. We have already acquired a private
2007 * fs_struct, so tsk->fs->lock is not needed.
2008 */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002009 p = mnt_ns->root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002010 q = new_ns->root;
2011 while (p) {
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002012 q->mnt_ns = new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002013 if (fs) {
Jan Blunck6ac08c32008-02-14 19:34:38 -08002014 if (p == fs->root.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002015 rootmnt = p;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002016 fs->root.mnt = mntget(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017 }
Jan Blunck6ac08c32008-02-14 19:34:38 -08002018 if (p == fs->pwd.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019 pwdmnt = p;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002020 fs->pwd.mnt = mntget(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002021 }
Jan Blunck6ac08c32008-02-14 19:34:38 -08002022 if (p == fs->altroot.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023 altrootmnt = p;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002024 fs->altroot.mnt = mntget(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002025 }
2026 }
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002027 p = next_mnt(p, mnt_ns->root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002028 q = next_mnt(q, new_ns->root);
2029 }
Ram Pai390c6842005-11-07 17:17:51 -05002030 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002031
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 if (rootmnt)
2033 mntput(rootmnt);
2034 if (pwdmnt)
2035 mntput(pwdmnt);
2036 if (altrootmnt)
2037 mntput(altrootmnt);
2038
JANAK DESAI741a2952006-02-07 12:59:00 -08002039 return new_ns;
2040}
2041
Eric W. Biederman213dd262007-07-15 23:41:15 -07002042struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
Badari Pulavartye3222c42007-05-08 00:25:21 -07002043 struct fs_struct *new_fs)
JANAK DESAI741a2952006-02-07 12:59:00 -08002044{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002045 struct mnt_namespace *new_ns;
JANAK DESAI741a2952006-02-07 12:59:00 -08002046
Badari Pulavartye3222c42007-05-08 00:25:21 -07002047 BUG_ON(!ns);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002048 get_mnt_ns(ns);
JANAK DESAI741a2952006-02-07 12:59:00 -08002049
2050 if (!(flags & CLONE_NEWNS))
Badari Pulavartye3222c42007-05-08 00:25:21 -07002051 return ns;
JANAK DESAI741a2952006-02-07 12:59:00 -08002052
Badari Pulavartye3222c42007-05-08 00:25:21 -07002053 new_ns = dup_mnt_ns(ns, new_fs);
JANAK DESAI741a2952006-02-07 12:59:00 -08002054
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002055 put_mnt_ns(ns);
Badari Pulavartye3222c42007-05-08 00:25:21 -07002056 return new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057}
2058
2059asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name,
2060 char __user * type, unsigned long flags,
2061 void __user * data)
2062{
2063 int retval;
2064 unsigned long data_page;
2065 unsigned long type_page;
2066 unsigned long dev_page;
2067 char *dir_page;
2068
Ram Paib58fed82005-11-07 17:16:09 -05002069 retval = copy_mount_options(type, &type_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 if (retval < 0)
2071 return retval;
2072
2073 dir_page = getname(dir_name);
2074 retval = PTR_ERR(dir_page);
2075 if (IS_ERR(dir_page))
2076 goto out1;
2077
Ram Paib58fed82005-11-07 17:16:09 -05002078 retval = copy_mount_options(dev_name, &dev_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079 if (retval < 0)
2080 goto out2;
2081
Ram Paib58fed82005-11-07 17:16:09 -05002082 retval = copy_mount_options(data, &data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083 if (retval < 0)
2084 goto out3;
2085
2086 lock_kernel();
Ram Paib58fed82005-11-07 17:16:09 -05002087 retval = do_mount((char *)dev_page, dir_page, (char *)type_page,
2088 flags, (void *)data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 unlock_kernel();
2090 free_page(data_page);
2091
2092out3:
2093 free_page(dev_page);
2094out2:
2095 putname(dir_page);
2096out1:
2097 free_page(type_page);
2098 return retval;
2099}
2100
2101/*
2102 * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
2103 * It can block. Requires the big lock held.
2104 */
Jan Blunckac748a02008-02-14 19:34:39 -08002105void set_fs_root(struct fs_struct *fs, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106{
Jan Blunck6ac08c32008-02-14 19:34:38 -08002107 struct path old_root;
2108
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 write_lock(&fs->lock);
2110 old_root = fs->root;
Jan Blunckac748a02008-02-14 19:34:39 -08002111 fs->root = *path;
2112 path_get(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 write_unlock(&fs->lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002114 if (old_root.dentry)
2115 path_put(&old_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002116}
2117
2118/*
2119 * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
2120 * It can block. Requires the big lock held.
2121 */
Jan Blunckac748a02008-02-14 19:34:39 -08002122void set_fs_pwd(struct fs_struct *fs, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002123{
Jan Blunck6ac08c32008-02-14 19:34:38 -08002124 struct path old_pwd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125
2126 write_lock(&fs->lock);
2127 old_pwd = fs->pwd;
Jan Blunckac748a02008-02-14 19:34:39 -08002128 fs->pwd = *path;
2129 path_get(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002130 write_unlock(&fs->lock);
2131
Jan Blunck6ac08c32008-02-14 19:34:38 -08002132 if (old_pwd.dentry)
2133 path_put(&old_pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002134}
2135
Al Viro1a390682008-03-21 20:48:19 -04002136static void chroot_fs_refs(struct path *old_root, struct path *new_root)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137{
2138 struct task_struct *g, *p;
2139 struct fs_struct *fs;
2140
2141 read_lock(&tasklist_lock);
2142 do_each_thread(g, p) {
2143 task_lock(p);
2144 fs = p->fs;
2145 if (fs) {
2146 atomic_inc(&fs->count);
2147 task_unlock(p);
Al Viro1a390682008-03-21 20:48:19 -04002148 if (fs->root.dentry == old_root->dentry
2149 && fs->root.mnt == old_root->mnt)
2150 set_fs_root(fs, new_root);
2151 if (fs->pwd.dentry == old_root->dentry
2152 && fs->pwd.mnt == old_root->mnt)
2153 set_fs_pwd(fs, new_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002154 put_fs_struct(fs);
2155 } else
2156 task_unlock(p);
2157 } while_each_thread(g, p);
2158 read_unlock(&tasklist_lock);
2159}
2160
2161/*
2162 * pivot_root Semantics:
2163 * Moves the root file system of the current process to the directory put_old,
2164 * makes new_root as the new root file system of the current process, and sets
2165 * root/cwd of all processes which had them on the current root to new_root.
2166 *
2167 * Restrictions:
2168 * The new_root and put_old must be directories, and must not be on the
2169 * same file system as the current process root. The put_old must be
2170 * underneath new_root, i.e. adding a non-zero number of /.. to the string
2171 * pointed to by put_old must yield the same directory as new_root. No other
2172 * file system may be mounted on put_old. After all, new_root is a mountpoint.
2173 *
Neil Brown4a0d11f2006-01-08 01:03:18 -08002174 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
2175 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
2176 * in this situation.
2177 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178 * Notes:
2179 * - we don't move root/cwd if they are not at the root (reason: if something
2180 * cared enough to change them, it's probably wrong to force them elsewhere)
2181 * - it's okay to pick a root that isn't the root of a file system, e.g.
2182 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
2183 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
2184 * first.
2185 */
Ram Paib58fed82005-11-07 17:16:09 -05002186asmlinkage long sys_pivot_root(const char __user * new_root,
2187 const char __user * put_old)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188{
2189 struct vfsmount *tmp;
Al Viro8c3ee422008-03-22 18:00:39 -04002190 struct nameidata new_nd, old_nd;
2191 struct path parent_path, root_parent, root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 int error;
2193
2194 if (!capable(CAP_SYS_ADMIN))
2195 return -EPERM;
2196
Ram Paib58fed82005-11-07 17:16:09 -05002197 error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
2198 &new_nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199 if (error)
2200 goto out0;
2201 error = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -08002202 if (!check_mnt(new_nd.path.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 goto out1;
2204
Ram Paib58fed82005-11-07 17:16:09 -05002205 error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002206 if (error)
2207 goto out1;
2208
Al Virob5266eb2008-03-22 17:48:24 -04002209 error = security_sb_pivotroot(&old_nd.path, &new_nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210 if (error) {
Jan Blunck1d957f92008-02-14 19:34:35 -08002211 path_put(&old_nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212 goto out1;
2213 }
2214
2215 read_lock(&current->fs->lock);
Al Viro8c3ee422008-03-22 18:00:39 -04002216 root = current->fs->root;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002217 path_get(&current->fs->root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218 read_unlock(&current->fs->lock);
Ram Pai390c6842005-11-07 17:17:51 -05002219 down_write(&namespace_sem);
Jan Blunck4ac91372008-02-14 19:34:32 -08002220 mutex_lock(&old_nd.path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 error = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -08002222 if (IS_MNT_SHARED(old_nd.path.mnt) ||
2223 IS_MNT_SHARED(new_nd.path.mnt->mnt_parent) ||
Al Viro8c3ee422008-03-22 18:00:39 -04002224 IS_MNT_SHARED(root.mnt->mnt_parent))
Ram Pai21444402005-11-07 17:20:03 -05002225 goto out2;
Al Viro8c3ee422008-03-22 18:00:39 -04002226 if (!check_mnt(root.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227 goto out2;
2228 error = -ENOENT;
Jan Blunck4ac91372008-02-14 19:34:32 -08002229 if (IS_DEADDIR(new_nd.path.dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002230 goto out2;
Jan Blunck4ac91372008-02-14 19:34:32 -08002231 if (d_unhashed(new_nd.path.dentry) && !IS_ROOT(new_nd.path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232 goto out2;
Jan Blunck4ac91372008-02-14 19:34:32 -08002233 if (d_unhashed(old_nd.path.dentry) && !IS_ROOT(old_nd.path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002234 goto out2;
2235 error = -EBUSY;
Al Viro8c3ee422008-03-22 18:00:39 -04002236 if (new_nd.path.mnt == root.mnt ||
2237 old_nd.path.mnt == root.mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 goto out2; /* loop, on the same file system */
2239 error = -EINVAL;
Al Viro8c3ee422008-03-22 18:00:39 -04002240 if (root.mnt->mnt_root != root.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241 goto out2; /* not a mountpoint */
Al Viro8c3ee422008-03-22 18:00:39 -04002242 if (root.mnt->mnt_parent == root.mnt)
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07002243 goto out2; /* not attached */
Jan Blunck4ac91372008-02-14 19:34:32 -08002244 if (new_nd.path.mnt->mnt_root != new_nd.path.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 goto out2; /* not a mountpoint */
Jan Blunck4ac91372008-02-14 19:34:32 -08002246 if (new_nd.path.mnt->mnt_parent == new_nd.path.mnt)
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07002247 goto out2; /* not attached */
Jan Blunck4ac91372008-02-14 19:34:32 -08002248 /* make sure we can reach put_old from new_root */
2249 tmp = old_nd.path.mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002250 spin_lock(&vfsmount_lock);
Jan Blunck4ac91372008-02-14 19:34:32 -08002251 if (tmp != new_nd.path.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252 for (;;) {
2253 if (tmp->mnt_parent == tmp)
2254 goto out3; /* already mounted on put_old */
Jan Blunck4ac91372008-02-14 19:34:32 -08002255 if (tmp->mnt_parent == new_nd.path.mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256 break;
2257 tmp = tmp->mnt_parent;
2258 }
Jan Blunck4ac91372008-02-14 19:34:32 -08002259 if (!is_subdir(tmp->mnt_mountpoint, new_nd.path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260 goto out3;
Jan Blunck4ac91372008-02-14 19:34:32 -08002261 } else if (!is_subdir(old_nd.path.dentry, new_nd.path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 goto out3;
Al Viro1a390682008-03-21 20:48:19 -04002263 detach_mnt(new_nd.path.mnt, &parent_path);
Al Viro8c3ee422008-03-22 18:00:39 -04002264 detach_mnt(root.mnt, &root_parent);
Jan Blunck4ac91372008-02-14 19:34:32 -08002265 /* mount old root on put_old */
Al Viro8c3ee422008-03-22 18:00:39 -04002266 attach_mnt(root.mnt, &old_nd.path);
Jan Blunck4ac91372008-02-14 19:34:32 -08002267 /* mount new_root on / */
2268 attach_mnt(new_nd.path.mnt, &root_parent);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002269 touch_mnt_namespace(current->nsproxy->mnt_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 spin_unlock(&vfsmount_lock);
Al Viro8c3ee422008-03-22 18:00:39 -04002271 chroot_fs_refs(&root, &new_nd.path);
2272 security_sb_post_pivotroot(&root, &new_nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273 error = 0;
Al Viro1a390682008-03-21 20:48:19 -04002274 path_put(&root_parent);
2275 path_put(&parent_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276out2:
Jan Blunck4ac91372008-02-14 19:34:32 -08002277 mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex);
Ram Pai390c6842005-11-07 17:17:51 -05002278 up_write(&namespace_sem);
Al Viro8c3ee422008-03-22 18:00:39 -04002279 path_put(&root);
Jan Blunck1d957f92008-02-14 19:34:35 -08002280 path_put(&old_nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002281out1:
Jan Blunck1d957f92008-02-14 19:34:35 -08002282 path_put(&new_nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283out0:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002284 return error;
2285out3:
2286 spin_unlock(&vfsmount_lock);
2287 goto out2;
2288}
2289
2290static void __init init_mount_tree(void)
2291{
2292 struct vfsmount *mnt;
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002293 struct mnt_namespace *ns;
Jan Blunckac748a02008-02-14 19:34:39 -08002294 struct path root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295
2296 mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
2297 if (IS_ERR(mnt))
2298 panic("Can't create rootfs");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002299 ns = kmalloc(sizeof(*ns), GFP_KERNEL);
2300 if (!ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 panic("Can't allocate initial namespace");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002302 atomic_set(&ns->count, 1);
2303 INIT_LIST_HEAD(&ns->list);
2304 init_waitqueue_head(&ns->poll);
2305 ns->event = 0;
2306 list_add(&mnt->mnt_list, &ns->list);
2307 ns->root = mnt;
2308 mnt->mnt_ns = ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002309
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002310 init_task.nsproxy->mnt_ns = ns;
2311 get_mnt_ns(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312
Jan Blunckac748a02008-02-14 19:34:39 -08002313 root.mnt = ns->root;
2314 root.dentry = ns->root->mnt_root;
2315
2316 set_fs_pwd(current->fs, &root);
2317 set_fs_root(current->fs, &root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318}
2319
Denis Cheng74bf17c2007-10-16 23:26:30 -07002320void __init mnt_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002321{
Eric Dumazet13f14b42008-02-06 01:37:57 -08002322 unsigned u;
Randy Dunlap15a67dd2006-09-29 01:58:57 -07002323 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324
Ram Pai390c6842005-11-07 17:17:51 -05002325 init_rwsem(&namespace_sem);
2326
Linus Torvalds1da177e2005-04-16 15:20:36 -07002327 mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
Paul Mundt20c2df82007-07-20 10:11:58 +09002328 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329
Ram Paib58fed82005-11-07 17:16:09 -05002330 mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331
2332 if (!mount_hashtable)
2333 panic("Failed to allocate mount hash table\n");
2334
Eric Dumazet13f14b42008-02-06 01:37:57 -08002335 printk("Mount-cache hash table entries: %lu\n", HASH_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336
Eric Dumazet13f14b42008-02-06 01:37:57 -08002337 for (u = 0; u < HASH_SIZE; u++)
2338 INIT_LIST_HEAD(&mount_hashtable[u]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002339
Randy Dunlap15a67dd2006-09-29 01:58:57 -07002340 err = sysfs_init();
2341 if (err)
2342 printk(KERN_WARNING "%s: sysfs_init error: %d\n",
2343 __FUNCTION__, err);
Greg Kroah-Hartman00d26662007-10-29 14:17:23 -06002344 fs_kobj = kobject_create_and_add("fs", NULL);
2345 if (!fs_kobj)
2346 printk(KERN_WARNING "%s: kobj create error\n", __FUNCTION__);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347 init_rootfs();
2348 init_mount_tree();
2349}
2350
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002351void __put_mnt_ns(struct mnt_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002353 struct vfsmount *root = ns->root;
Ram Pai70fbcdf2005-11-07 17:17:04 -05002354 LIST_HEAD(umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002355 ns->root = NULL;
Miklos Szeredi1ce88cf2005-07-07 17:57:24 -07002356 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05002357 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002358 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05002359 umount_tree(root, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002360 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05002361 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -05002362 release_mounts(&umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002363 kfree(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002364}