blob: 228d8c4bfd18a1925fd57ac3880e2e47031470d2 [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);
Li Zefan88b38782008-07-21 18:06:36 +0800115 if (err)
116 goto out_free_cache;
117
118 if (name) {
119 mnt->mnt_devname = kstrdup(name, GFP_KERNEL);
120 if (!mnt->mnt_devname)
121 goto out_free_id;
Miklos Szeredi73cd49e2008-03-26 22:11:34 +0100122 }
123
Ram Paib58fed82005-11-07 17:16:09 -0500124 atomic_set(&mnt->mnt_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 INIT_LIST_HEAD(&mnt->mnt_hash);
126 INIT_LIST_HEAD(&mnt->mnt_child);
127 INIT_LIST_HEAD(&mnt->mnt_mounts);
128 INIT_LIST_HEAD(&mnt->mnt_list);
Miklos Szeredi55e700b2005-07-07 17:57:30 -0700129 INIT_LIST_HEAD(&mnt->mnt_expire);
Ram Pai03e06e62005-11-07 17:19:33 -0500130 INIT_LIST_HEAD(&mnt->mnt_share);
Ram Paia58b0eb2005-11-07 17:20:48 -0500131 INIT_LIST_HEAD(&mnt->mnt_slave_list);
132 INIT_LIST_HEAD(&mnt->mnt_slave);
Dave Hansen3d733632008-02-15 14:37:59 -0800133 atomic_set(&mnt->__mnt_writers, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 }
135 return mnt;
Li Zefan88b38782008-07-21 18:06:36 +0800136
137out_free_id:
138 mnt_free_id(mnt);
139out_free_cache:
140 kmem_cache_free(mnt_cache, mnt);
141 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142}
143
Dave Hansen83660252008-02-15 14:37:30 -0800144/*
145 * Most r/o checks on a fs are for operations that take
146 * discrete amounts of time, like a write() or unlink().
147 * We must keep track of when those operations start
148 * (for permission checks) and when they end, so that
149 * we can determine when writes are able to occur to
150 * a filesystem.
151 */
Dave Hansen3d733632008-02-15 14:37:59 -0800152/*
153 * __mnt_is_readonly: check whether a mount is read-only
154 * @mnt: the mount to check for its write status
155 *
156 * This shouldn't be used directly ouside of the VFS.
157 * It does not guarantee that the filesystem will stay
158 * r/w, just that it is right *now*. This can not and
159 * should not be used in place of IS_RDONLY(inode).
160 * mnt_want/drop_write() will _keep_ the filesystem
161 * r/w.
162 */
163int __mnt_is_readonly(struct vfsmount *mnt)
164{
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800165 if (mnt->mnt_flags & MNT_READONLY)
166 return 1;
167 if (mnt->mnt_sb->s_flags & MS_RDONLY)
168 return 1;
169 return 0;
Dave Hansen3d733632008-02-15 14:37:59 -0800170}
171EXPORT_SYMBOL_GPL(__mnt_is_readonly);
172
173struct mnt_writer {
174 /*
175 * If holding multiple instances of this lock, they
176 * must be ordered by cpu number.
177 */
178 spinlock_t lock;
179 struct lock_class_key lock_class; /* compiles out with !lockdep */
180 unsigned long count;
181 struct vfsmount *mnt;
182} ____cacheline_aligned_in_smp;
183static DEFINE_PER_CPU(struct mnt_writer, mnt_writers);
184
185static int __init init_mnt_writers(void)
186{
187 int cpu;
188 for_each_possible_cpu(cpu) {
189 struct mnt_writer *writer = &per_cpu(mnt_writers, cpu);
190 spin_lock_init(&writer->lock);
191 lockdep_set_class(&writer->lock, &writer->lock_class);
192 writer->count = 0;
193 }
194 return 0;
195}
196fs_initcall(init_mnt_writers);
197
198static void unlock_mnt_writers(void)
199{
200 int cpu;
201 struct mnt_writer *cpu_writer;
202
203 for_each_possible_cpu(cpu) {
204 cpu_writer = &per_cpu(mnt_writers, cpu);
205 spin_unlock(&cpu_writer->lock);
206 }
207}
208
209static inline void __clear_mnt_count(struct mnt_writer *cpu_writer)
210{
211 if (!cpu_writer->mnt)
212 return;
213 /*
214 * This is in case anyone ever leaves an invalid,
215 * old ->mnt and a count of 0.
216 */
217 if (!cpu_writer->count)
218 return;
219 atomic_add(cpu_writer->count, &cpu_writer->mnt->__mnt_writers);
220 cpu_writer->count = 0;
221}
222 /*
223 * must hold cpu_writer->lock
224 */
225static inline void use_cpu_writer_for_mount(struct mnt_writer *cpu_writer,
226 struct vfsmount *mnt)
227{
228 if (cpu_writer->mnt == mnt)
229 return;
230 __clear_mnt_count(cpu_writer);
231 cpu_writer->mnt = mnt;
232}
233
234/*
235 * Most r/o checks on a fs are for operations that take
236 * discrete amounts of time, like a write() or unlink().
237 * We must keep track of when those operations start
238 * (for permission checks) and when they end, so that
239 * we can determine when writes are able to occur to
240 * a filesystem.
241 */
Dave Hansen83660252008-02-15 14:37:30 -0800242/**
243 * mnt_want_write - get write access to a mount
244 * @mnt: the mount on which to take a write
245 *
246 * This tells the low-level filesystem that a write is
247 * about to be performed to it, and makes sure that
248 * writes are allowed before returning success. When
249 * the write operation is finished, mnt_drop_write()
250 * must be called. This is effectively a refcount.
251 */
252int mnt_want_write(struct vfsmount *mnt)
253{
Dave Hansen3d733632008-02-15 14:37:59 -0800254 int ret = 0;
255 struct mnt_writer *cpu_writer;
256
257 cpu_writer = &get_cpu_var(mnt_writers);
258 spin_lock(&cpu_writer->lock);
259 if (__mnt_is_readonly(mnt)) {
260 ret = -EROFS;
261 goto out;
262 }
263 use_cpu_writer_for_mount(cpu_writer, mnt);
264 cpu_writer->count++;
265out:
266 spin_unlock(&cpu_writer->lock);
267 put_cpu_var(mnt_writers);
268 return ret;
Dave Hansen83660252008-02-15 14:37:30 -0800269}
270EXPORT_SYMBOL_GPL(mnt_want_write);
271
Dave Hansen3d733632008-02-15 14:37:59 -0800272static void lock_mnt_writers(void)
273{
274 int cpu;
275 struct mnt_writer *cpu_writer;
276
277 for_each_possible_cpu(cpu) {
278 cpu_writer = &per_cpu(mnt_writers, cpu);
279 spin_lock(&cpu_writer->lock);
280 __clear_mnt_count(cpu_writer);
281 cpu_writer->mnt = NULL;
282 }
283}
284
285/*
286 * These per-cpu write counts are not guaranteed to have
287 * matched increments and decrements on any given cpu.
288 * A file open()ed for write on one cpu and close()d on
289 * another cpu will imbalance this count. Make sure it
290 * does not get too far out of whack.
291 */
292static void handle_write_count_underflow(struct vfsmount *mnt)
293{
294 if (atomic_read(&mnt->__mnt_writers) >=
295 MNT_WRITER_UNDERFLOW_LIMIT)
296 return;
297 /*
298 * It isn't necessary to hold all of the locks
299 * at the same time, but doing it this way makes
300 * us share a lot more code.
301 */
302 lock_mnt_writers();
303 /*
304 * vfsmount_lock is for mnt_flags.
305 */
306 spin_lock(&vfsmount_lock);
307 /*
308 * If coalescing the per-cpu writer counts did not
309 * get us back to a positive writer count, we have
310 * a bug.
311 */
312 if ((atomic_read(&mnt->__mnt_writers) < 0) &&
313 !(mnt->mnt_flags & MNT_IMBALANCED_WRITE_COUNT)) {
Arjan van de Ven5c752ad2008-07-25 19:45:40 -0700314 WARN(1, KERN_DEBUG "leak detected on mount(%p) writers "
Dave Hansen3d733632008-02-15 14:37:59 -0800315 "count: %d\n",
316 mnt, atomic_read(&mnt->__mnt_writers));
Dave Hansen3d733632008-02-15 14:37:59 -0800317 /* use the flag to keep the dmesg spam down */
318 mnt->mnt_flags |= MNT_IMBALANCED_WRITE_COUNT;
319 }
320 spin_unlock(&vfsmount_lock);
321 unlock_mnt_writers();
322}
323
Dave Hansen83660252008-02-15 14:37:30 -0800324/**
325 * mnt_drop_write - give up write access to a mount
326 * @mnt: the mount on which to give up write access
327 *
328 * Tells the low-level filesystem that we are done
329 * performing writes to it. Must be matched with
330 * mnt_want_write() call above.
331 */
332void mnt_drop_write(struct vfsmount *mnt)
333{
Dave Hansen3d733632008-02-15 14:37:59 -0800334 int must_check_underflow = 0;
335 struct mnt_writer *cpu_writer;
336
337 cpu_writer = &get_cpu_var(mnt_writers);
338 spin_lock(&cpu_writer->lock);
339
340 use_cpu_writer_for_mount(cpu_writer, mnt);
341 if (cpu_writer->count > 0) {
342 cpu_writer->count--;
343 } else {
344 must_check_underflow = 1;
345 atomic_dec(&mnt->__mnt_writers);
346 }
347
348 spin_unlock(&cpu_writer->lock);
349 /*
350 * Logically, we could call this each time,
351 * but the __mnt_writers cacheline tends to
352 * be cold, and makes this expensive.
353 */
354 if (must_check_underflow)
355 handle_write_count_underflow(mnt);
356 /*
357 * This could be done right after the spinlock
358 * is taken because the spinlock keeps us on
359 * the cpu, and disables preemption. However,
360 * putting it here bounds the amount that
361 * __mnt_writers can underflow. Without it,
362 * we could theoretically wrap __mnt_writers.
363 */
364 put_cpu_var(mnt_writers);
Dave Hansen83660252008-02-15 14:37:30 -0800365}
366EXPORT_SYMBOL_GPL(mnt_drop_write);
367
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800368static int mnt_make_readonly(struct vfsmount *mnt)
Dave Hansen83660252008-02-15 14:37:30 -0800369{
Dave Hansen3d733632008-02-15 14:37:59 -0800370 int ret = 0;
371
372 lock_mnt_writers();
373 /*
374 * With all the locks held, this value is stable
375 */
376 if (atomic_read(&mnt->__mnt_writers) > 0) {
377 ret = -EBUSY;
378 goto out;
379 }
380 /*
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800381 * nobody can do a successful mnt_want_write() with all
382 * of the counts in MNT_DENIED_WRITE and the locks held.
Dave Hansen3d733632008-02-15 14:37:59 -0800383 */
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800384 spin_lock(&vfsmount_lock);
385 if (!ret)
386 mnt->mnt_flags |= MNT_READONLY;
387 spin_unlock(&vfsmount_lock);
Dave Hansen3d733632008-02-15 14:37:59 -0800388out:
389 unlock_mnt_writers();
390 return ret;
Dave Hansen83660252008-02-15 14:37:30 -0800391}
Dave Hansen83660252008-02-15 14:37:30 -0800392
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800393static void __mnt_unmake_readonly(struct vfsmount *mnt)
394{
395 spin_lock(&vfsmount_lock);
396 mnt->mnt_flags &= ~MNT_READONLY;
397 spin_unlock(&vfsmount_lock);
398}
399
David Howells454e2392006-06-23 02:02:57 -0700400int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
401{
402 mnt->mnt_sb = sb;
403 mnt->mnt_root = dget(sb->s_root);
404 return 0;
405}
406
407EXPORT_SYMBOL(simple_set_mnt);
408
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409void free_vfsmnt(struct vfsmount *mnt)
410{
411 kfree(mnt->mnt_devname);
Miklos Szeredi73cd49e2008-03-26 22:11:34 +0100412 mnt_free_id(mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 kmem_cache_free(mnt_cache, mnt);
414}
415
416/*
Ram Paia05964f2005-11-07 17:20:17 -0500417 * find the first or last mount at @dentry on vfsmount @mnt depending on
418 * @dir. If @dir is set return the first mount else return the last mount.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 */
Ram Paia05964f2005-11-07 17:20:17 -0500420struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
421 int dir)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422{
Ram Paib58fed82005-11-07 17:16:09 -0500423 struct list_head *head = mount_hashtable + hash(mnt, dentry);
424 struct list_head *tmp = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425 struct vfsmount *p, *found = NULL;
426
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 for (;;) {
Ram Paia05964f2005-11-07 17:20:17 -0500428 tmp = dir ? tmp->next : tmp->prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 p = NULL;
430 if (tmp == head)
431 break;
432 p = list_entry(tmp, struct vfsmount, mnt_hash);
433 if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
Ram Paia05964f2005-11-07 17:20:17 -0500434 found = p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 break;
436 }
437 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 return found;
439}
440
Ram Paia05964f2005-11-07 17:20:17 -0500441/*
442 * lookup_mnt increments the ref count before returning
443 * the vfsmount struct.
444 */
445struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
446{
447 struct vfsmount *child_mnt;
448 spin_lock(&vfsmount_lock);
449 if ((child_mnt = __lookup_mnt(mnt, dentry, 1)))
450 mntget(child_mnt);
451 spin_unlock(&vfsmount_lock);
452 return child_mnt;
453}
454
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455static inline int check_mnt(struct vfsmount *mnt)
456{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800457 return mnt->mnt_ns == current->nsproxy->mnt_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458}
459
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800460static void touch_mnt_namespace(struct mnt_namespace *ns)
Al Viro5addc5d2005-11-07 17:15:49 -0500461{
462 if (ns) {
463 ns->event = ++event;
464 wake_up_interruptible(&ns->poll);
465 }
466}
467
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800468static void __touch_mnt_namespace(struct mnt_namespace *ns)
Al Viro5addc5d2005-11-07 17:15:49 -0500469{
470 if (ns && ns->event != event) {
471 ns->event = event;
472 wake_up_interruptible(&ns->poll);
473 }
474}
475
Al Viro1a390682008-03-21 20:48:19 -0400476static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477{
Al Viro1a390682008-03-21 20:48:19 -0400478 old_path->dentry = mnt->mnt_mountpoint;
479 old_path->mnt = mnt->mnt_parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 mnt->mnt_parent = mnt;
481 mnt->mnt_mountpoint = mnt->mnt_root;
482 list_del_init(&mnt->mnt_child);
483 list_del_init(&mnt->mnt_hash);
Al Viro1a390682008-03-21 20:48:19 -0400484 old_path->dentry->d_mounted--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485}
486
Ram Paib90fa9a2005-11-07 17:19:50 -0500487void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
488 struct vfsmount *child_mnt)
489{
490 child_mnt->mnt_parent = mntget(mnt);
491 child_mnt->mnt_mountpoint = dget(dentry);
492 dentry->d_mounted++;
493}
494
Al Viro1a390682008-03-21 20:48:19 -0400495static void attach_mnt(struct vfsmount *mnt, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496{
Al Viro1a390682008-03-21 20:48:19 -0400497 mnt_set_mountpoint(path->mnt, path->dentry, mnt);
Ram Paib90fa9a2005-11-07 17:19:50 -0500498 list_add_tail(&mnt->mnt_hash, mount_hashtable +
Al Viro1a390682008-03-21 20:48:19 -0400499 hash(path->mnt, path->dentry));
500 list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
Ram Paib90fa9a2005-11-07 17:19:50 -0500501}
502
503/*
504 * the caller must hold vfsmount_lock
505 */
506static void commit_tree(struct vfsmount *mnt)
507{
508 struct vfsmount *parent = mnt->mnt_parent;
509 struct vfsmount *m;
510 LIST_HEAD(head);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800511 struct mnt_namespace *n = parent->mnt_ns;
Ram Paib90fa9a2005-11-07 17:19:50 -0500512
513 BUG_ON(parent == mnt);
514
515 list_add_tail(&head, &mnt->mnt_list);
516 list_for_each_entry(m, &head, mnt_list)
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800517 m->mnt_ns = n;
Ram Paib90fa9a2005-11-07 17:19:50 -0500518 list_splice(&head, n->list.prev);
519
520 list_add_tail(&mnt->mnt_hash, mount_hashtable +
521 hash(parent, mnt->mnt_mountpoint));
522 list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -0800523 touch_mnt_namespace(n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524}
525
526static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
527{
528 struct list_head *next = p->mnt_mounts.next;
529 if (next == &p->mnt_mounts) {
530 while (1) {
531 if (p == root)
532 return NULL;
533 next = p->mnt_child.next;
534 if (next != &p->mnt_parent->mnt_mounts)
535 break;
536 p = p->mnt_parent;
537 }
538 }
539 return list_entry(next, struct vfsmount, mnt_child);
540}
541
Ram Pai9676f0c2005-11-07 17:21:20 -0500542static struct vfsmount *skip_mnt_tree(struct vfsmount *p)
543{
544 struct list_head *prev = p->mnt_mounts.prev;
545 while (prev != &p->mnt_mounts) {
546 p = list_entry(prev, struct vfsmount, mnt_child);
547 prev = p->mnt_mounts.prev;
548 }
549 return p;
550}
551
Ram Pai36341f62005-11-07 17:17:22 -0500552static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
553 int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554{
555 struct super_block *sb = old->mnt_sb;
556 struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
557
558 if (mnt) {
Miklos Szeredi719f5d72008-03-27 13:06:23 +0100559 if (flag & (CL_SLAVE | CL_PRIVATE))
560 mnt->mnt_group_id = 0; /* not a peer of original */
561 else
562 mnt->mnt_group_id = old->mnt_group_id;
563
564 if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
565 int err = mnt_alloc_group_id(mnt);
566 if (err)
567 goto out_free;
568 }
569
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 mnt->mnt_flags = old->mnt_flags;
571 atomic_inc(&sb->s_active);
572 mnt->mnt_sb = sb;
573 mnt->mnt_root = dget(root);
574 mnt->mnt_mountpoint = mnt->mnt_root;
575 mnt->mnt_parent = mnt;
Ram Paib90fa9a2005-11-07 17:19:50 -0500576
Ram Pai5afe0022005-11-07 17:21:01 -0500577 if (flag & CL_SLAVE) {
578 list_add(&mnt->mnt_slave, &old->mnt_slave_list);
579 mnt->mnt_master = old;
580 CLEAR_MNT_SHARED(mnt);
Al Viro8aec0802007-06-07 12:20:32 -0400581 } else if (!(flag & CL_PRIVATE)) {
Ram Pai5afe0022005-11-07 17:21:01 -0500582 if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
583 list_add(&mnt->mnt_share, &old->mnt_share);
584 if (IS_MNT_SLAVE(old))
585 list_add(&mnt->mnt_slave, &old->mnt_slave);
586 mnt->mnt_master = old->mnt_master;
587 }
Ram Paib90fa9a2005-11-07 17:19:50 -0500588 if (flag & CL_MAKE_SHARED)
589 set_mnt_shared(mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590
591 /* stick the duplicate mount on the same expiry list
592 * as the original if that was on one */
Ram Pai36341f62005-11-07 17:17:22 -0500593 if (flag & CL_EXPIRE) {
Ram Pai36341f62005-11-07 17:17:22 -0500594 if (!list_empty(&old->mnt_expire))
595 list_add(&mnt->mnt_expire, &old->mnt_expire);
Ram Pai36341f62005-11-07 17:17:22 -0500596 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 }
598 return mnt;
Miklos Szeredi719f5d72008-03-27 13:06:23 +0100599
600 out_free:
601 free_vfsmnt(mnt);
602 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603}
604
Al Viro7b7b1ac2005-11-07 17:13:39 -0500605static inline void __mntput(struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606{
Dave Hansen3d733632008-02-15 14:37:59 -0800607 int cpu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 struct super_block *sb = mnt->mnt_sb;
Dave Hansen3d733632008-02-15 14:37:59 -0800609 /*
610 * We don't have to hold all of the locks at the
611 * same time here because we know that we're the
612 * last reference to mnt and that no new writers
613 * can come in.
614 */
615 for_each_possible_cpu(cpu) {
616 struct mnt_writer *cpu_writer = &per_cpu(mnt_writers, cpu);
617 if (cpu_writer->mnt != mnt)
618 continue;
619 spin_lock(&cpu_writer->lock);
620 atomic_add(cpu_writer->count, &mnt->__mnt_writers);
621 cpu_writer->count = 0;
622 /*
623 * Might as well do this so that no one
624 * ever sees the pointer and expects
625 * it to be valid.
626 */
627 cpu_writer->mnt = NULL;
628 spin_unlock(&cpu_writer->lock);
629 }
630 /*
631 * This probably indicates that somebody messed
632 * up a mnt_want/drop_write() pair. If this
633 * happens, the filesystem was probably unable
634 * to make r/w->r/o transitions.
635 */
636 WARN_ON(atomic_read(&mnt->__mnt_writers));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 dput(mnt->mnt_root);
638 free_vfsmnt(mnt);
639 deactivate_super(sb);
640}
641
Al Viro7b7b1ac2005-11-07 17:13:39 -0500642void mntput_no_expire(struct vfsmount *mnt)
643{
644repeat:
645 if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
646 if (likely(!mnt->mnt_pinned)) {
647 spin_unlock(&vfsmount_lock);
648 __mntput(mnt);
649 return;
650 }
651 atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
652 mnt->mnt_pinned = 0;
653 spin_unlock(&vfsmount_lock);
654 acct_auto_close_mnt(mnt);
655 security_sb_umount_close(mnt);
656 goto repeat;
657 }
658}
659
660EXPORT_SYMBOL(mntput_no_expire);
661
662void mnt_pin(struct vfsmount *mnt)
663{
664 spin_lock(&vfsmount_lock);
665 mnt->mnt_pinned++;
666 spin_unlock(&vfsmount_lock);
667}
668
669EXPORT_SYMBOL(mnt_pin);
670
671void mnt_unpin(struct vfsmount *mnt)
672{
673 spin_lock(&vfsmount_lock);
674 if (mnt->mnt_pinned) {
675 atomic_inc(&mnt->mnt_count);
676 mnt->mnt_pinned--;
677 }
678 spin_unlock(&vfsmount_lock);
679}
680
681EXPORT_SYMBOL(mnt_unpin);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
Miklos Szeredib3b304a2008-02-08 04:21:35 -0800683static inline void mangle(struct seq_file *m, const char *s)
684{
685 seq_escape(m, s, " \t\n\\");
686}
687
688/*
689 * Simple .show_options callback for filesystems which don't want to
690 * implement more complex mount option showing.
691 *
692 * See also save_mount_options().
693 */
694int generic_show_options(struct seq_file *m, struct vfsmount *mnt)
695{
696 const char *options = mnt->mnt_sb->s_options;
697
698 if (options != NULL && options[0]) {
699 seq_putc(m, ',');
700 mangle(m, options);
701 }
702
703 return 0;
704}
705EXPORT_SYMBOL(generic_show_options);
706
707/*
708 * If filesystem uses generic_show_options(), this function should be
709 * called from the fill_super() callback.
710 *
711 * The .remount_fs callback usually needs to be handled in a special
712 * way, to make sure, that previous options are not overwritten if the
713 * remount fails.
714 *
715 * Also note, that if the filesystem's .remount_fs function doesn't
716 * reset all options to their default value, but changes only newly
717 * given options, then the displayed options will not reflect reality
718 * any more.
719 */
720void save_mount_options(struct super_block *sb, char *options)
721{
722 kfree(sb->s_options);
723 sb->s_options = kstrdup(options, GFP_KERNEL);
724}
725EXPORT_SYMBOL(save_mount_options);
726
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100727#ifdef CONFIG_PROC_FS
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728/* iterator */
729static void *m_start(struct seq_file *m, loff_t *pos)
730{
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100731 struct proc_mounts *p = m->private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732
Ram Pai390c6842005-11-07 17:17:51 -0500733 down_read(&namespace_sem);
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100734 return seq_list_start(&p->ns->list, *pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735}
736
737static void *m_next(struct seq_file *m, void *v, loff_t *pos)
738{
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100739 struct proc_mounts *p = m->private;
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700740
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100741 return seq_list_next(v, &p->ns->list, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742}
743
744static void m_stop(struct seq_file *m, void *v)
745{
Ram Pai390c6842005-11-07 17:17:51 -0500746 up_read(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747}
748
Ram Pai2d4d4862008-03-27 13:06:25 +0100749struct proc_fs_info {
750 int flag;
751 const char *str;
752};
753
Eric Paris2069f452008-07-04 09:47:13 +1000754static int show_sb_opts(struct seq_file *m, struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755{
Ram Pai2d4d4862008-03-27 13:06:25 +0100756 static const struct proc_fs_info fs_info[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 { MS_SYNCHRONOUS, ",sync" },
758 { MS_DIRSYNC, ",dirsync" },
759 { MS_MANDLOCK, ",mand" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 { 0, NULL }
761 };
Ram Pai2d4d4862008-03-27 13:06:25 +0100762 const struct proc_fs_info *fs_infop;
763
764 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
765 if (sb->s_flags & fs_infop->flag)
766 seq_puts(m, fs_infop->str);
767 }
Eric Paris2069f452008-07-04 09:47:13 +1000768
769 return security_sb_show_options(m, sb);
Ram Pai2d4d4862008-03-27 13:06:25 +0100770}
771
772static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
773{
774 static const struct proc_fs_info mnt_info[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 { MNT_NOSUID, ",nosuid" },
776 { MNT_NODEV, ",nodev" },
777 { MNT_NOEXEC, ",noexec" },
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -0800778 { MNT_NOATIME, ",noatime" },
779 { MNT_NODIRATIME, ",nodiratime" },
Valerie Henson47ae32d2006-12-13 00:34:34 -0800780 { MNT_RELATIME, ",relatime" },
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 { 0, NULL }
782 };
Ram Pai2d4d4862008-03-27 13:06:25 +0100783 const struct proc_fs_info *fs_infop;
784
785 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
786 if (mnt->mnt_flags & fs_infop->flag)
787 seq_puts(m, fs_infop->str);
788 }
789}
790
791static void show_type(struct seq_file *m, struct super_block *sb)
792{
793 mangle(m, sb->s_type->name);
794 if (sb->s_subtype && sb->s_subtype[0]) {
795 seq_putc(m, '.');
796 mangle(m, sb->s_subtype);
797 }
798}
799
800static int show_vfsmnt(struct seq_file *m, void *v)
801{
802 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
803 int err = 0;
Jan Blunckc32c2f62008-02-14 19:38:43 -0800804 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805
806 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
807 seq_putc(m, ' ');
Jan Blunckc32c2f62008-02-14 19:38:43 -0800808 seq_path(m, &mnt_path, " \t\n\\");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 seq_putc(m, ' ');
Ram Pai2d4d4862008-03-27 13:06:25 +0100810 show_type(m, mnt->mnt_sb);
Dave Hansen2e4b7fc2008-02-15 14:38:00 -0800811 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
Eric Paris2069f452008-07-04 09:47:13 +1000812 err = show_sb_opts(m, mnt->mnt_sb);
813 if (err)
814 goto out;
Ram Pai2d4d4862008-03-27 13:06:25 +0100815 show_mnt_opts(m, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 if (mnt->mnt_sb->s_op->show_options)
817 err = mnt->mnt_sb->s_op->show_options(m, mnt);
818 seq_puts(m, " 0 0\n");
Eric Paris2069f452008-07-04 09:47:13 +1000819out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 return err;
821}
822
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100823const struct seq_operations mounts_op = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 .start = m_start,
825 .next = m_next,
826 .stop = m_stop,
827 .show = show_vfsmnt
828};
829
Ram Pai2d4d4862008-03-27 13:06:25 +0100830static int show_mountinfo(struct seq_file *m, void *v)
831{
832 struct proc_mounts *p = m->private;
833 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
834 struct super_block *sb = mnt->mnt_sb;
835 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
836 struct path root = p->root;
837 int err = 0;
838
839 seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
840 MAJOR(sb->s_dev), MINOR(sb->s_dev));
841 seq_dentry(m, mnt->mnt_root, " \t\n\\");
842 seq_putc(m, ' ');
843 seq_path_root(m, &mnt_path, &root, " \t\n\\");
844 if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
845 /*
846 * Mountpoint is outside root, discard that one. Ugly,
847 * but less so than trying to do that in iterator in a
848 * race-free way (due to renames).
849 */
850 return SEQ_SKIP;
851 }
852 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
853 show_mnt_opts(m, mnt);
854
855 /* Tagged fields ("foo:X" or "bar") */
856 if (IS_MNT_SHARED(mnt))
857 seq_printf(m, " shared:%i", mnt->mnt_group_id);
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +0100858 if (IS_MNT_SLAVE(mnt)) {
859 int master = mnt->mnt_master->mnt_group_id;
860 int dom = get_dominating_id(mnt, &p->root);
861 seq_printf(m, " master:%i", master);
862 if (dom && dom != master)
863 seq_printf(m, " propagate_from:%i", dom);
864 }
Ram Pai2d4d4862008-03-27 13:06:25 +0100865 if (IS_MNT_UNBINDABLE(mnt))
866 seq_puts(m, " unbindable");
867
868 /* Filesystem specific data */
869 seq_puts(m, " - ");
870 show_type(m, sb);
871 seq_putc(m, ' ');
872 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
873 seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
Eric Paris2069f452008-07-04 09:47:13 +1000874 err = show_sb_opts(m, sb);
875 if (err)
876 goto out;
Ram Pai2d4d4862008-03-27 13:06:25 +0100877 if (sb->s_op->show_options)
878 err = sb->s_op->show_options(m, mnt);
879 seq_putc(m, '\n');
Eric Paris2069f452008-07-04 09:47:13 +1000880out:
Ram Pai2d4d4862008-03-27 13:06:25 +0100881 return err;
882}
883
884const struct seq_operations mountinfo_op = {
885 .start = m_start,
886 .next = m_next,
887 .stop = m_stop,
888 .show = show_mountinfo,
889};
890
Chuck Leverb4629fe2006-03-20 13:44:12 -0500891static int show_vfsstat(struct seq_file *m, void *v)
892{
Pavel Emelianovb0765fb2007-07-15 23:39:55 -0700893 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
Jan Blunckc32c2f62008-02-14 19:38:43 -0800894 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
Chuck Leverb4629fe2006-03-20 13:44:12 -0500895 int err = 0;
896
897 /* device */
898 if (mnt->mnt_devname) {
899 seq_puts(m, "device ");
900 mangle(m, mnt->mnt_devname);
901 } else
902 seq_puts(m, "no device");
903
904 /* mount point */
905 seq_puts(m, " mounted on ");
Jan Blunckc32c2f62008-02-14 19:38:43 -0800906 seq_path(m, &mnt_path, " \t\n\\");
Chuck Leverb4629fe2006-03-20 13:44:12 -0500907 seq_putc(m, ' ');
908
909 /* file system type */
910 seq_puts(m, "with fstype ");
Ram Pai2d4d4862008-03-27 13:06:25 +0100911 show_type(m, mnt->mnt_sb);
Chuck Leverb4629fe2006-03-20 13:44:12 -0500912
913 /* optional statistics */
914 if (mnt->mnt_sb->s_op->show_stats) {
915 seq_putc(m, ' ');
916 err = mnt->mnt_sb->s_op->show_stats(m, mnt);
917 }
918
919 seq_putc(m, '\n');
920 return err;
921}
922
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100923const struct seq_operations mountstats_op = {
Chuck Leverb4629fe2006-03-20 13:44:12 -0500924 .start = m_start,
925 .next = m_next,
926 .stop = m_stop,
927 .show = show_vfsstat,
928};
Miklos Szeredia1a2c402008-03-27 13:06:24 +0100929#endif /* CONFIG_PROC_FS */
Chuck Leverb4629fe2006-03-20 13:44:12 -0500930
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931/**
932 * may_umount_tree - check if a mount tree is busy
933 * @mnt: root of mount tree
934 *
935 * This is called to check if a tree of mounts has any
936 * open files, pwds, chroots or sub mounts that are
937 * busy.
938 */
939int may_umount_tree(struct vfsmount *mnt)
940{
Ram Pai36341f62005-11-07 17:17:22 -0500941 int actual_refs = 0;
942 int minimum_refs = 0;
943 struct vfsmount *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944
945 spin_lock(&vfsmount_lock);
Ram Pai36341f62005-11-07 17:17:22 -0500946 for (p = mnt; p; p = next_mnt(p, mnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947 actual_refs += atomic_read(&p->mnt_count);
948 minimum_refs += 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 }
950 spin_unlock(&vfsmount_lock);
951
952 if (actual_refs > minimum_refs)
Ian Kente3474a82006-03-27 01:14:51 -0800953 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954
Ian Kente3474a82006-03-27 01:14:51 -0800955 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956}
957
958EXPORT_SYMBOL(may_umount_tree);
959
960/**
961 * may_umount - check if a mount point is busy
962 * @mnt: root of mount
963 *
964 * This is called to check if a mount point has any
965 * open files, pwds, chroots or sub mounts. If the
966 * mount has sub mounts this will return busy
967 * regardless of whether the sub mounts are busy.
968 *
969 * Doesn't take quota and stuff into account. IOW, in some cases it will
970 * give false negatives. The main reason why it's here is that we need
971 * a non-destructive way to look for easily umountable filesystems.
972 */
973int may_umount(struct vfsmount *mnt)
974{
Ian Kente3474a82006-03-27 01:14:51 -0800975 int ret = 1;
Ram Paia05964f2005-11-07 17:20:17 -0500976 spin_lock(&vfsmount_lock);
977 if (propagate_mount_busy(mnt, 2))
Ian Kente3474a82006-03-27 01:14:51 -0800978 ret = 0;
Ram Paia05964f2005-11-07 17:20:17 -0500979 spin_unlock(&vfsmount_lock);
980 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981}
982
983EXPORT_SYMBOL(may_umount);
984
Ram Paib90fa9a2005-11-07 17:19:50 -0500985void release_mounts(struct list_head *head)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986{
Ram Pai70fbcdf2005-11-07 17:17:04 -0500987 struct vfsmount *mnt;
Miklos Szeredibf066c72006-01-08 01:03:19 -0800988 while (!list_empty(head)) {
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700989 mnt = list_first_entry(head, struct vfsmount, mnt_hash);
Ram Pai70fbcdf2005-11-07 17:17:04 -0500990 list_del_init(&mnt->mnt_hash);
991 if (mnt->mnt_parent != mnt) {
992 struct dentry *dentry;
993 struct vfsmount *m;
994 spin_lock(&vfsmount_lock);
995 dentry = mnt->mnt_mountpoint;
996 m = mnt->mnt_parent;
997 mnt->mnt_mountpoint = mnt->mnt_root;
998 mnt->mnt_parent = mnt;
Al Viro7c4b93d2008-03-21 23:59:49 -0400999 m->mnt_ghosts--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001001 dput(dentry);
1002 mntput(m);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 }
1004 mntput(mnt);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001005 }
1006}
1007
Ram Paia05964f2005-11-07 17:20:17 -05001008void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
Ram Pai70fbcdf2005-11-07 17:17:04 -05001009{
1010 struct vfsmount *p;
1011
Akinobu Mita1bfba4e2006-06-26 00:24:40 -07001012 for (p = mnt; p; p = next_mnt(p, mnt))
1013 list_move(&p->mnt_hash, kill);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001014
Ram Paia05964f2005-11-07 17:20:17 -05001015 if (propagate)
1016 propagate_umount(kill);
1017
Ram Pai70fbcdf2005-11-07 17:17:04 -05001018 list_for_each_entry(p, kill, mnt_hash) {
1019 list_del_init(&p->mnt_expire);
1020 list_del_init(&p->mnt_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001021 __touch_mnt_namespace(p->mnt_ns);
1022 p->mnt_ns = NULL;
Ram Pai70fbcdf2005-11-07 17:17:04 -05001023 list_del_init(&p->mnt_child);
Al Viro7c4b93d2008-03-21 23:59:49 -04001024 if (p->mnt_parent != p) {
1025 p->mnt_parent->mnt_ghosts++;
Al Virof30ac312006-02-01 07:53:21 -05001026 p->mnt_mountpoint->d_mounted--;
Al Viro7c4b93d2008-03-21 23:59:49 -04001027 }
Ram Paia05964f2005-11-07 17:20:17 -05001028 change_mnt_propagation(p, MS_PRIVATE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 }
1030}
1031
Al Viroc35038b2008-03-22 00:46:23 -04001032static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts);
1033
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034static int do_umount(struct vfsmount *mnt, int flags)
1035{
Ram Paib58fed82005-11-07 17:16:09 -05001036 struct super_block *sb = mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 int retval;
Ram Pai70fbcdf2005-11-07 17:17:04 -05001038 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039
1040 retval = security_sb_umount(mnt, flags);
1041 if (retval)
1042 return retval;
1043
1044 /*
1045 * Allow userspace to request a mountpoint be expired rather than
1046 * unmounting unconditionally. Unmount only happens if:
1047 * (1) the mark is already set (the mark is cleared by mntput())
1048 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
1049 */
1050 if (flags & MNT_EXPIRE) {
Jan Blunck6ac08c32008-02-14 19:34:38 -08001051 if (mnt == current->fs->root.mnt ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 flags & (MNT_FORCE | MNT_DETACH))
1053 return -EINVAL;
1054
1055 if (atomic_read(&mnt->mnt_count) != 2)
1056 return -EBUSY;
1057
1058 if (!xchg(&mnt->mnt_expiry_mark, 1))
1059 return -EAGAIN;
1060 }
1061
1062 /*
1063 * If we may have to abort operations to get out of this
1064 * mount, and they will themselves hold resources we must
1065 * allow the fs to do things. In the Unix tradition of
1066 * 'Gee thats tricky lets do it in userspace' the umount_begin
1067 * might fail to complete on the first run through as other tasks
1068 * must return, and the like. Thats for the mount program to worry
1069 * about for the moment.
1070 */
1071
Al Viro42faad92008-04-24 07:21:56 -04001072 if (flags & MNT_FORCE && sb->s_op->umount_begin) {
1073 lock_kernel();
1074 sb->s_op->umount_begin(sb);
1075 unlock_kernel();
1076 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077
1078 /*
1079 * No sense to grab the lock for this test, but test itself looks
1080 * somewhat bogus. Suggestions for better replacement?
1081 * Ho-hum... In principle, we might treat that as umount + switch
1082 * to rootfs. GC would eventually take care of the old vfsmount.
1083 * Actually it makes sense, especially if rootfs would contain a
1084 * /reboot - static binary that would close all descriptors and
1085 * call reboot(9). Then init(8) could umount root and exec /reboot.
1086 */
Jan Blunck6ac08c32008-02-14 19:34:38 -08001087 if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 /*
1089 * Special case for "unmounting" root ...
1090 * we just try to remount it readonly.
1091 */
1092 down_write(&sb->s_umount);
1093 if (!(sb->s_flags & MS_RDONLY)) {
1094 lock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
1096 unlock_kernel();
1097 }
1098 up_write(&sb->s_umount);
1099 return retval;
1100 }
1101
Ram Pai390c6842005-11-07 17:17:51 -05001102 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 spin_lock(&vfsmount_lock);
Al Viro5addc5d2005-11-07 17:15:49 -05001104 event++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105
Al Viroc35038b2008-03-22 00:46:23 -04001106 if (!(flags & MNT_DETACH))
1107 shrink_submounts(mnt, &umount_list);
1108
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109 retval = -EBUSY;
Ram Paia05964f2005-11-07 17:20:17 -05001110 if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111 if (!list_empty(&mnt->mnt_list))
Ram Paia05964f2005-11-07 17:20:17 -05001112 umount_tree(mnt, 1, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 retval = 0;
1114 }
1115 spin_unlock(&vfsmount_lock);
1116 if (retval)
1117 security_sb_umount_busy(mnt);
Ram Pai390c6842005-11-07 17:17:51 -05001118 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001119 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 return retval;
1121}
1122
1123/*
1124 * Now umount can handle mount points as well as block devices.
1125 * This is important for filesystems which use unnamed block devices.
1126 *
1127 * We now support a flag for forced unmount like the other 'big iron'
1128 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
1129 */
1130
Heiko Carstensbdc480e2009-01-14 14:14:12 +01001131SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132{
Al Viro2d8f3032008-07-22 09:59:21 -04001133 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 int retval;
1135
Al Viro2d8f3032008-07-22 09:59:21 -04001136 retval = user_path(name, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 if (retval)
1138 goto out;
1139 retval = -EINVAL;
Al Viro2d8f3032008-07-22 09:59:21 -04001140 if (path.dentry != path.mnt->mnt_root)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 goto dput_and_out;
Al Viro2d8f3032008-07-22 09:59:21 -04001142 if (!check_mnt(path.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 goto dput_and_out;
1144
1145 retval = -EPERM;
1146 if (!capable(CAP_SYS_ADMIN))
1147 goto dput_and_out;
1148
Al Viro2d8f3032008-07-22 09:59:21 -04001149 retval = do_umount(path.mnt, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150dput_and_out:
Jan Blunck429731b2008-02-14 19:34:31 -08001151 /* we mustn't call path_put() as that would clear mnt_expiry_mark */
Al Viro2d8f3032008-07-22 09:59:21 -04001152 dput(path.dentry);
1153 mntput_no_expire(path.mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154out:
1155 return retval;
1156}
1157
1158#ifdef __ARCH_WANT_SYS_OLDUMOUNT
1159
1160/*
Ram Paib58fed82005-11-07 17:16:09 -05001161 * The 2.0 compatible umount. No flags.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 */
Heiko Carstensbdc480e2009-01-14 14:14:12 +01001163SYSCALL_DEFINE1(oldumount, char __user *, name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164{
Ram Paib58fed82005-11-07 17:16:09 -05001165 return sys_umount(name, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166}
1167
1168#endif
1169
Al Viro2d92ab32008-08-02 00:51:11 -04001170static int mount_is_safe(struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171{
1172 if (capable(CAP_SYS_ADMIN))
1173 return 0;
1174 return -EPERM;
1175#ifdef notyet
Al Viro2d92ab32008-08-02 00:51:11 -04001176 if (S_ISLNK(path->dentry->d_inode->i_mode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 return -EPERM;
Al Viro2d92ab32008-08-02 00:51:11 -04001178 if (path->dentry->d_inode->i_mode & S_ISVTX) {
David Howellsda9592e2008-11-14 10:39:05 +11001179 if (current_uid() != path->dentry->d_inode->i_uid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 return -EPERM;
1181 }
Al Viro2d92ab32008-08-02 00:51:11 -04001182 if (inode_permission(path->dentry->d_inode, MAY_WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183 return -EPERM;
1184 return 0;
1185#endif
1186}
1187
Ram Paib90fa9a2005-11-07 17:19:50 -05001188struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
Ram Pai36341f62005-11-07 17:17:22 -05001189 int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190{
1191 struct vfsmount *res, *p, *q, *r, *s;
Al Viro1a390682008-03-21 20:48:19 -04001192 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193
Ram Pai9676f0c2005-11-07 17:21:20 -05001194 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
1195 return NULL;
1196
Ram Pai36341f62005-11-07 17:17:22 -05001197 res = q = clone_mnt(mnt, dentry, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 if (!q)
1199 goto Enomem;
1200 q->mnt_mountpoint = mnt->mnt_mountpoint;
1201
1202 p = mnt;
Domen Puncerfdadd652005-09-10 00:27:07 -07001203 list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
Jan Blunck7ec02ef2008-04-29 00:59:40 -07001204 if (!is_subdir(r->mnt_mountpoint, dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 continue;
1206
1207 for (s = r; s; s = next_mnt(s, r)) {
Ram Pai9676f0c2005-11-07 17:21:20 -05001208 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
1209 s = skip_mnt_tree(s);
1210 continue;
1211 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 while (p != s->mnt_parent) {
1213 p = p->mnt_parent;
1214 q = q->mnt_parent;
1215 }
1216 p = s;
Al Viro1a390682008-03-21 20:48:19 -04001217 path.mnt = q;
1218 path.dentry = p->mnt_mountpoint;
Ram Pai36341f62005-11-07 17:17:22 -05001219 q = clone_mnt(p, p->mnt_root, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 if (!q)
1221 goto Enomem;
1222 spin_lock(&vfsmount_lock);
1223 list_add_tail(&q->mnt_list, &res->mnt_list);
Al Viro1a390682008-03-21 20:48:19 -04001224 attach_mnt(q, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 spin_unlock(&vfsmount_lock);
1226 }
1227 }
1228 return res;
Ram Paib58fed82005-11-07 17:16:09 -05001229Enomem:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230 if (res) {
Ram Pai70fbcdf2005-11-07 17:17:04 -05001231 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05001233 umount_tree(res, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001235 release_mounts(&umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236 }
1237 return NULL;
1238}
1239
Al Viro8aec0802007-06-07 12:20:32 -04001240struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)
1241{
1242 struct vfsmount *tree;
Al Viro1a60a282008-03-22 16:19:49 -04001243 down_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001244 tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE);
Al Viro1a60a282008-03-22 16:19:49 -04001245 up_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001246 return tree;
1247}
1248
1249void drop_collected_mounts(struct vfsmount *mnt)
1250{
1251 LIST_HEAD(umount_list);
Al Viro1a60a282008-03-22 16:19:49 -04001252 down_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001253 spin_lock(&vfsmount_lock);
1254 umount_tree(mnt, 0, &umount_list);
1255 spin_unlock(&vfsmount_lock);
Al Viro1a60a282008-03-22 16:19:49 -04001256 up_write(&namespace_sem);
Al Viro8aec0802007-06-07 12:20:32 -04001257 release_mounts(&umount_list);
1258}
1259
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001260static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end)
1261{
1262 struct vfsmount *p;
1263
1264 for (p = mnt; p != end; p = next_mnt(p, mnt)) {
1265 if (p->mnt_group_id && !IS_MNT_SHARED(p))
1266 mnt_release_group_id(p);
1267 }
1268}
1269
1270static int invent_group_ids(struct vfsmount *mnt, bool recurse)
1271{
1272 struct vfsmount *p;
1273
1274 for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) {
1275 if (!p->mnt_group_id && !IS_MNT_SHARED(p)) {
1276 int err = mnt_alloc_group_id(p);
1277 if (err) {
1278 cleanup_group_ids(mnt, p);
1279 return err;
1280 }
1281 }
1282 }
1283
1284 return 0;
1285}
1286
Ram Paib90fa9a2005-11-07 17:19:50 -05001287/*
1288 * @source_mnt : mount tree to be attached
Ram Pai21444402005-11-07 17:20:03 -05001289 * @nd : place the mount tree @source_mnt is attached
1290 * @parent_nd : if non-null, detach the source_mnt from its parent and
1291 * store the parent mount and mountpoint dentry.
1292 * (done when source_mnt is moved)
Ram Paib90fa9a2005-11-07 17:19:50 -05001293 *
1294 * NOTE: in the table below explains the semantics when a source mount
1295 * of a given type is attached to a destination mount of a given type.
Ram Pai9676f0c2005-11-07 17:21:20 -05001296 * ---------------------------------------------------------------------------
1297 * | BIND MOUNT OPERATION |
1298 * |**************************************************************************
1299 * | source-->| shared | private | slave | unbindable |
1300 * | dest | | | | |
1301 * | | | | | | |
1302 * | v | | | | |
1303 * |**************************************************************************
1304 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
1305 * | | | | | |
1306 * |non-shared| shared (+) | private | slave (*) | invalid |
1307 * ***************************************************************************
Ram Paib90fa9a2005-11-07 17:19:50 -05001308 * A bind operation clones the source mount and mounts the clone on the
1309 * destination mount.
1310 *
1311 * (++) the cloned mount is propagated to all the mounts in the propagation
1312 * tree of the destination mount and the cloned mount is added to
1313 * the peer group of the source mount.
1314 * (+) the cloned mount is created under the destination mount and is marked
1315 * as shared. The cloned mount is added to the peer group of the source
1316 * mount.
Ram Pai5afe0022005-11-07 17:21:01 -05001317 * (+++) the mount is propagated to all the mounts in the propagation tree
1318 * of the destination mount and the cloned mount is made slave
1319 * of the same master as that of the source mount. The cloned mount
1320 * is marked as 'shared and slave'.
1321 * (*) the cloned mount is made a slave of the same master as that of the
1322 * source mount.
1323 *
Ram Pai9676f0c2005-11-07 17:21:20 -05001324 * ---------------------------------------------------------------------------
1325 * | MOVE MOUNT OPERATION |
1326 * |**************************************************************************
1327 * | source-->| shared | private | slave | unbindable |
1328 * | dest | | | | |
1329 * | | | | | | |
1330 * | v | | | | |
1331 * |**************************************************************************
1332 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
1333 * | | | | | |
1334 * |non-shared| shared (+*) | private | slave (*) | unbindable |
1335 * ***************************************************************************
Ram Pai5afe0022005-11-07 17:21:01 -05001336 *
1337 * (+) the mount is moved to the destination. And is then propagated to
1338 * all the mounts in the propagation tree of the destination mount.
Ram Pai21444402005-11-07 17:20:03 -05001339 * (+*) the mount is moved to the destination.
Ram Pai5afe0022005-11-07 17:21:01 -05001340 * (+++) the mount is moved to the destination and is then propagated to
1341 * all the mounts belonging to the destination mount's propagation tree.
1342 * the mount is marked as 'shared and slave'.
1343 * (*) the mount continues to be a slave at the new location.
Ram Paib90fa9a2005-11-07 17:19:50 -05001344 *
1345 * if the source mount is a tree, the operations explained above is
1346 * applied to each mount in the tree.
1347 * Must be called without spinlocks held, since this function can sleep
1348 * in allocations.
1349 */
1350static int attach_recursive_mnt(struct vfsmount *source_mnt,
Al Viro1a390682008-03-21 20:48:19 -04001351 struct path *path, struct path *parent_path)
Ram Paib90fa9a2005-11-07 17:19:50 -05001352{
1353 LIST_HEAD(tree_list);
Al Viro1a390682008-03-21 20:48:19 -04001354 struct vfsmount *dest_mnt = path->mnt;
1355 struct dentry *dest_dentry = path->dentry;
Ram Paib90fa9a2005-11-07 17:19:50 -05001356 struct vfsmount *child, *p;
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001357 int err;
Ram Paib90fa9a2005-11-07 17:19:50 -05001358
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001359 if (IS_MNT_SHARED(dest_mnt)) {
1360 err = invent_group_ids(source_mnt, true);
1361 if (err)
1362 goto out;
1363 }
1364 err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list);
1365 if (err)
1366 goto out_cleanup_ids;
Ram Paib90fa9a2005-11-07 17:19:50 -05001367
1368 if (IS_MNT_SHARED(dest_mnt)) {
1369 for (p = source_mnt; p; p = next_mnt(p, source_mnt))
1370 set_mnt_shared(p);
1371 }
1372
1373 spin_lock(&vfsmount_lock);
Al Viro1a390682008-03-21 20:48:19 -04001374 if (parent_path) {
1375 detach_mnt(source_mnt, parent_path);
1376 attach_mnt(source_mnt, path);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001377 touch_mnt_namespace(current->nsproxy->mnt_ns);
Ram Pai21444402005-11-07 17:20:03 -05001378 } else {
1379 mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
1380 commit_tree(source_mnt);
1381 }
Ram Paib90fa9a2005-11-07 17:19:50 -05001382
1383 list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
1384 list_del_init(&child->mnt_hash);
1385 commit_tree(child);
1386 }
1387 spin_unlock(&vfsmount_lock);
1388 return 0;
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001389
1390 out_cleanup_ids:
1391 if (IS_MNT_SHARED(dest_mnt))
1392 cleanup_group_ids(source_mnt, NULL);
1393 out:
1394 return err;
Ram Paib90fa9a2005-11-07 17:19:50 -05001395}
1396
Al Viro8c3ee422008-03-22 18:00:39 -04001397static int graft_tree(struct vfsmount *mnt, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398{
1399 int err;
1400 if (mnt->mnt_sb->s_flags & MS_NOUSER)
1401 return -EINVAL;
1402
Al Viro8c3ee422008-03-22 18:00:39 -04001403 if (S_ISDIR(path->dentry->d_inode->i_mode) !=
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 S_ISDIR(mnt->mnt_root->d_inode->i_mode))
1405 return -ENOTDIR;
1406
1407 err = -ENOENT;
Al Viro8c3ee422008-03-22 18:00:39 -04001408 mutex_lock(&path->dentry->d_inode->i_mutex);
1409 if (IS_DEADDIR(path->dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 goto out_unlock;
1411
Al Viro8c3ee422008-03-22 18:00:39 -04001412 err = security_sb_check_sb(mnt, path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 if (err)
1414 goto out_unlock;
1415
1416 err = -ENOENT;
Al Viro8c3ee422008-03-22 18:00:39 -04001417 if (IS_ROOT(path->dentry) || !d_unhashed(path->dentry))
1418 err = attach_recursive_mnt(mnt, path, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419out_unlock:
Al Viro8c3ee422008-03-22 18:00:39 -04001420 mutex_unlock(&path->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421 if (!err)
Al Viro8c3ee422008-03-22 18:00:39 -04001422 security_sb_post_addmount(mnt, path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 return err;
1424}
1425
1426/*
Ram Pai07b20882005-11-07 17:19:07 -05001427 * recursively change the type of the mountpoint.
1428 */
Al Viro0a0d8a42008-08-02 00:55:27 -04001429static int do_change_type(struct path *path, int flag)
Ram Pai07b20882005-11-07 17:19:07 -05001430{
Al Viro2d92ab32008-08-02 00:51:11 -04001431 struct vfsmount *m, *mnt = path->mnt;
Ram Pai07b20882005-11-07 17:19:07 -05001432 int recurse = flag & MS_REC;
1433 int type = flag & ~MS_REC;
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001434 int err = 0;
Ram Pai07b20882005-11-07 17:19:07 -05001435
Miklos Szerediee6f9582007-05-08 00:30:40 -07001436 if (!capable(CAP_SYS_ADMIN))
1437 return -EPERM;
1438
Al Viro2d92ab32008-08-02 00:51:11 -04001439 if (path->dentry != path->mnt->mnt_root)
Ram Pai07b20882005-11-07 17:19:07 -05001440 return -EINVAL;
1441
1442 down_write(&namespace_sem);
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001443 if (type == MS_SHARED) {
1444 err = invent_group_ids(mnt, recurse);
1445 if (err)
1446 goto out_unlock;
1447 }
1448
Ram Pai07b20882005-11-07 17:19:07 -05001449 spin_lock(&vfsmount_lock);
1450 for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
1451 change_mnt_propagation(m, type);
1452 spin_unlock(&vfsmount_lock);
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001453
1454 out_unlock:
Ram Pai07b20882005-11-07 17:19:07 -05001455 up_write(&namespace_sem);
Miklos Szeredi719f5d72008-03-27 13:06:23 +01001456 return err;
Ram Pai07b20882005-11-07 17:19:07 -05001457}
1458
1459/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 * do loopback mount.
1461 */
Al Viro0a0d8a42008-08-02 00:55:27 -04001462static int do_loopback(struct path *path, char *old_name,
Eric Sandeen2dafe1c2008-02-08 04:22:12 -08001463 int recurse)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464{
Al Viro2d92ab32008-08-02 00:51:11 -04001465 struct path old_path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 struct vfsmount *mnt = NULL;
Al Viro2d92ab32008-08-02 00:51:11 -04001467 int err = mount_is_safe(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 if (err)
1469 return err;
1470 if (!old_name || !*old_name)
1471 return -EINVAL;
Al Viro2d92ab32008-08-02 00:51:11 -04001472 err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 if (err)
1474 return err;
1475
Ram Pai390c6842005-11-07 17:17:51 -05001476 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 err = -EINVAL;
Al Viro2d92ab32008-08-02 00:51:11 -04001478 if (IS_MNT_UNBINDABLE(old_path.mnt))
Jan Blunck4ac91372008-02-14 19:34:32 -08001479 goto out;
Ram Pai9676f0c2005-11-07 17:21:20 -05001480
Al Viro2d92ab32008-08-02 00:51:11 -04001481 if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
Al Viroccd48bc2005-11-07 17:15:04 -05001482 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483
Al Viroccd48bc2005-11-07 17:15:04 -05001484 err = -ENOMEM;
1485 if (recurse)
Al Viro2d92ab32008-08-02 00:51:11 -04001486 mnt = copy_tree(old_path.mnt, old_path.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -05001487 else
Al Viro2d92ab32008-08-02 00:51:11 -04001488 mnt = clone_mnt(old_path.mnt, old_path.dentry, 0);
Al Viroccd48bc2005-11-07 17:15:04 -05001489
1490 if (!mnt)
1491 goto out;
1492
Al Viro2d92ab32008-08-02 00:51:11 -04001493 err = graft_tree(mnt, path);
Al Viroccd48bc2005-11-07 17:15:04 -05001494 if (err) {
Ram Pai70fbcdf2005-11-07 17:17:04 -05001495 LIST_HEAD(umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05001497 umount_tree(mnt, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498 spin_unlock(&vfsmount_lock);
Ram Pai70fbcdf2005-11-07 17:17:04 -05001499 release_mounts(&umount_list);
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001500 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501
Al Viroccd48bc2005-11-07 17:15:04 -05001502out:
Ram Pai390c6842005-11-07 17:17:51 -05001503 up_write(&namespace_sem);
Al Viro2d92ab32008-08-02 00:51:11 -04001504 path_put(&old_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 return err;
1506}
1507
Dave Hansen2e4b7fc2008-02-15 14:38:00 -08001508static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
1509{
1510 int error = 0;
1511 int readonly_request = 0;
1512
1513 if (ms_flags & MS_RDONLY)
1514 readonly_request = 1;
1515 if (readonly_request == __mnt_is_readonly(mnt))
1516 return 0;
1517
1518 if (readonly_request)
1519 error = mnt_make_readonly(mnt);
1520 else
1521 __mnt_unmake_readonly(mnt);
1522 return error;
1523}
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525/*
1526 * change filesystem flags. dir should be a physical root of filesystem.
1527 * If you've mounted a non-root directory somewhere and want to do remount
1528 * on it - tough luck.
1529 */
Al Viro0a0d8a42008-08-02 00:55:27 -04001530static int do_remount(struct path *path, int flags, int mnt_flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 void *data)
1532{
1533 int err;
Al Viro2d92ab32008-08-02 00:51:11 -04001534 struct super_block *sb = path->mnt->mnt_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535
1536 if (!capable(CAP_SYS_ADMIN))
1537 return -EPERM;
1538
Al Viro2d92ab32008-08-02 00:51:11 -04001539 if (!check_mnt(path->mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 return -EINVAL;
1541
Al Viro2d92ab32008-08-02 00:51:11 -04001542 if (path->dentry != path->mnt->mnt_root)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 return -EINVAL;
1544
1545 down_write(&sb->s_umount);
Dave Hansen2e4b7fc2008-02-15 14:38:00 -08001546 if (flags & MS_BIND)
Al Viro2d92ab32008-08-02 00:51:11 -04001547 err = change_mount_flags(path->mnt, flags);
Dave Hansen2e4b7fc2008-02-15 14:38:00 -08001548 else
1549 err = do_remount_sb(sb, flags, data, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 if (!err)
Al Viro2d92ab32008-08-02 00:51:11 -04001551 path->mnt->mnt_flags = mnt_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 up_write(&sb->s_umount);
Dan Williams0e55a7c2008-09-26 19:01:20 -07001553 if (!err) {
Al Viro2d92ab32008-08-02 00:51:11 -04001554 security_sb_post_remount(path->mnt, flags, data);
Dan Williams0e55a7c2008-09-26 19:01:20 -07001555
1556 spin_lock(&vfsmount_lock);
1557 touch_mnt_namespace(path->mnt->mnt_ns);
1558 spin_unlock(&vfsmount_lock);
1559 }
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
Al Viro0a0d8a42008-08-02 00:55:27 -04001573static int do_move_mount(struct path *path, char *old_name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574{
Al Viro2d92ab32008-08-02 00:51:11 -04001575 struct path old_path, parent_path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576 struct vfsmount *p;
1577 int err = 0;
1578 if (!capable(CAP_SYS_ADMIN))
1579 return -EPERM;
1580 if (!old_name || !*old_name)
1581 return -EINVAL;
Al Viro2d92ab32008-08-02 00:51:11 -04001582 err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 if (err)
1584 return err;
1585
Ram Pai390c6842005-11-07 17:17:51 -05001586 down_write(&namespace_sem);
Al Viro2d92ab32008-08-02 00:51:11 -04001587 while (d_mountpoint(path->dentry) &&
1588 follow_down(&path->mnt, &path->dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 ;
1590 err = -EINVAL;
Al Viro2d92ab32008-08-02 00:51:11 -04001591 if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592 goto out;
1593
1594 err = -ENOENT;
Al Viro2d92ab32008-08-02 00:51:11 -04001595 mutex_lock(&path->dentry->d_inode->i_mutex);
1596 if (IS_DEADDIR(path->dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597 goto out1;
1598
Al Viro2d92ab32008-08-02 00:51:11 -04001599 if (!IS_ROOT(path->dentry) && d_unhashed(path->dentry))
Ram Pai21444402005-11-07 17:20:03 -05001600 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601
1602 err = -EINVAL;
Al Viro2d92ab32008-08-02 00:51:11 -04001603 if (old_path.dentry != old_path.mnt->mnt_root)
Ram Pai21444402005-11-07 17:20:03 -05001604 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605
Al Viro2d92ab32008-08-02 00:51:11 -04001606 if (old_path.mnt == old_path.mnt->mnt_parent)
Ram Pai21444402005-11-07 17:20:03 -05001607 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608
Al Viro2d92ab32008-08-02 00:51:11 -04001609 if (S_ISDIR(path->dentry->d_inode->i_mode) !=
1610 S_ISDIR(old_path.dentry->d_inode->i_mode))
Ram Pai21444402005-11-07 17:20:03 -05001611 goto out1;
1612 /*
1613 * Don't move a mount residing in a shared parent.
1614 */
Al Viro2d92ab32008-08-02 00:51:11 -04001615 if (old_path.mnt->mnt_parent &&
1616 IS_MNT_SHARED(old_path.mnt->mnt_parent))
Ram Pai21444402005-11-07 17:20:03 -05001617 goto out1;
Ram Pai9676f0c2005-11-07 17:21:20 -05001618 /*
1619 * Don't move a mount tree containing unbindable mounts to a destination
1620 * mount which is shared.
1621 */
Al Viro2d92ab32008-08-02 00:51:11 -04001622 if (IS_MNT_SHARED(path->mnt) &&
1623 tree_contains_unbindable(old_path.mnt))
Ram Pai9676f0c2005-11-07 17:21:20 -05001624 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625 err = -ELOOP;
Al Viro2d92ab32008-08-02 00:51:11 -04001626 for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent)
1627 if (p == old_path.mnt)
Ram Pai21444402005-11-07 17:20:03 -05001628 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629
Al Viro2d92ab32008-08-02 00:51:11 -04001630 err = attach_recursive_mnt(old_path.mnt, path, &parent_path);
Jan Blunck4ac91372008-02-14 19:34:32 -08001631 if (err)
Ram Pai21444402005-11-07 17:20:03 -05001632 goto out1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633
1634 /* if the mount is moved, it should no longer be expire
1635 * automatically */
Al Viro2d92ab32008-08-02 00:51:11 -04001636 list_del_init(&old_path.mnt->mnt_expire);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637out1:
Al Viro2d92ab32008-08-02 00:51:11 -04001638 mutex_unlock(&path->dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639out:
Ram Pai390c6842005-11-07 17:17:51 -05001640 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 if (!err)
Al Viro1a390682008-03-21 20:48:19 -04001642 path_put(&parent_path);
Al Viro2d92ab32008-08-02 00:51:11 -04001643 path_put(&old_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 return err;
1645}
1646
1647/*
1648 * create a new mount for userspace and request it to be added into the
1649 * namespace's tree
1650 */
Al Viro0a0d8a42008-08-02 00:55:27 -04001651static int do_new_mount(struct path *path, char *type, int flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 int mnt_flags, char *name, void *data)
1653{
1654 struct vfsmount *mnt;
1655
1656 if (!type || !memchr(type, 0, PAGE_SIZE))
1657 return -EINVAL;
1658
1659 /* we need capabilities... */
1660 if (!capable(CAP_SYS_ADMIN))
1661 return -EPERM;
1662
1663 mnt = do_kern_mount(type, flags, name, data);
1664 if (IS_ERR(mnt))
1665 return PTR_ERR(mnt);
1666
Al Viro2d92ab32008-08-02 00:51:11 -04001667 return do_add_mount(mnt, path, mnt_flags, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668}
1669
1670/*
1671 * add a mount into a namespace's mount tree
1672 * - provide the option of adding the new mount to an expiration list
1673 */
Al Viro8d66bf52008-08-01 09:05:54 -04001674int do_add_mount(struct vfsmount *newmnt, struct path *path,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675 int mnt_flags, struct list_head *fslist)
1676{
1677 int err;
1678
Ram Pai390c6842005-11-07 17:17:51 -05001679 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 /* Something was mounted here while we slept */
Al Viro8d66bf52008-08-01 09:05:54 -04001681 while (d_mountpoint(path->dentry) &&
1682 follow_down(&path->mnt, &path->dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 ;
1684 err = -EINVAL;
Al Viro8d66bf52008-08-01 09:05:54 -04001685 if (!check_mnt(path->mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 goto unlock;
1687
1688 /* Refuse the same filesystem on the same mount point */
1689 err = -EBUSY;
Al Viro8d66bf52008-08-01 09:05:54 -04001690 if (path->mnt->mnt_sb == newmnt->mnt_sb &&
1691 path->mnt->mnt_root == path->dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 goto unlock;
1693
1694 err = -EINVAL;
1695 if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
1696 goto unlock;
1697
1698 newmnt->mnt_flags = mnt_flags;
Al Viro8d66bf52008-08-01 09:05:54 -04001699 if ((err = graft_tree(newmnt, path)))
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001700 goto unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701
Al Viro6758f952008-03-22 16:14:30 -04001702 if (fslist) /* add to the specified expiration list */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001703 list_add_tail(&newmnt->mnt_expire, fslist);
Al Viro6758f952008-03-22 16:14:30 -04001704
Ram Pai390c6842005-11-07 17:17:51 -05001705 up_write(&namespace_sem);
Ram Pai5b83d2c5c2005-11-07 17:16:29 -05001706 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707
1708unlock:
Ram Pai390c6842005-11-07 17:17:51 -05001709 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710 mntput(newmnt);
1711 return err;
1712}
1713
1714EXPORT_SYMBOL_GPL(do_add_mount);
1715
Trond Myklebust5528f9112006-06-09 09:34:17 -04001716/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 * process a list of expirable mountpoints with the intent of discarding any
1718 * mountpoints that aren't in use and haven't been touched since last we came
1719 * here
1720 */
1721void mark_mounts_for_expiry(struct list_head *mounts)
1722{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723 struct vfsmount *mnt, *next;
1724 LIST_HEAD(graveyard);
Al Virobcc5c7d2008-03-22 00:21:53 -04001725 LIST_HEAD(umounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726
1727 if (list_empty(mounts))
1728 return;
1729
Al Virobcc5c7d2008-03-22 00:21:53 -04001730 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 spin_lock(&vfsmount_lock);
1732
1733 /* extract from the expiration list every vfsmount that matches the
1734 * following criteria:
1735 * - only referenced by its parent vfsmount
1736 * - still marked for expiry (marked on the last call here; marks are
1737 * cleared by mntput())
1738 */
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001739 list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001740 if (!xchg(&mnt->mnt_expiry_mark, 1) ||
Al Virobcc5c7d2008-03-22 00:21:53 -04001741 propagate_mount_busy(mnt, 1))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 continue;
Miklos Szeredi55e700b2005-07-07 17:57:30 -07001743 list_move(&mnt->mnt_expire, &graveyard);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 }
Al Virobcc5c7d2008-03-22 00:21:53 -04001745 while (!list_empty(&graveyard)) {
1746 mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire);
1747 touch_mnt_namespace(mnt->mnt_ns);
1748 umount_tree(mnt, 1, &umounts);
1749 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750 spin_unlock(&vfsmount_lock);
Al Virobcc5c7d2008-03-22 00:21:53 -04001751 up_write(&namespace_sem);
1752
1753 release_mounts(&umounts);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754}
1755
1756EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
1757
1758/*
Trond Myklebust5528f9112006-06-09 09:34:17 -04001759 * Ripoff of 'select_parent()'
1760 *
1761 * search the list of submounts for a given mountpoint, and move any
1762 * shrinkable submounts to the 'graveyard' list.
1763 */
1764static int select_submounts(struct vfsmount *parent, struct list_head *graveyard)
1765{
1766 struct vfsmount *this_parent = parent;
1767 struct list_head *next;
1768 int found = 0;
1769
1770repeat:
1771 next = this_parent->mnt_mounts.next;
1772resume:
1773 while (next != &this_parent->mnt_mounts) {
1774 struct list_head *tmp = next;
1775 struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child);
1776
1777 next = tmp->next;
1778 if (!(mnt->mnt_flags & MNT_SHRINKABLE))
1779 continue;
1780 /*
1781 * Descend a level if the d_mounts list is non-empty.
1782 */
1783 if (!list_empty(&mnt->mnt_mounts)) {
1784 this_parent = mnt;
1785 goto repeat;
1786 }
1787
1788 if (!propagate_mount_busy(mnt, 1)) {
Trond Myklebust5528f9112006-06-09 09:34:17 -04001789 list_move_tail(&mnt->mnt_expire, graveyard);
1790 found++;
1791 }
1792 }
1793 /*
1794 * All done at this level ... ascend and resume the search
1795 */
1796 if (this_parent != parent) {
1797 next = this_parent->mnt_child.next;
1798 this_parent = this_parent->mnt_parent;
1799 goto resume;
1800 }
1801 return found;
1802}
1803
1804/*
1805 * process a list of expirable mountpoints with the intent of discarding any
1806 * submounts of a specific parent mountpoint
1807 */
Al Viroc35038b2008-03-22 00:46:23 -04001808static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts)
Trond Myklebust5528f9112006-06-09 09:34:17 -04001809{
1810 LIST_HEAD(graveyard);
Al Viroc35038b2008-03-22 00:46:23 -04001811 struct vfsmount *m;
Trond Myklebust5528f9112006-06-09 09:34:17 -04001812
Trond Myklebust5528f9112006-06-09 09:34:17 -04001813 /* extract submounts of 'mountpoint' from the expiration list */
Al Viroc35038b2008-03-22 00:46:23 -04001814 while (select_submounts(mnt, &graveyard)) {
Al Virobcc5c7d2008-03-22 00:21:53 -04001815 while (!list_empty(&graveyard)) {
Al Viroc35038b2008-03-22 00:46:23 -04001816 m = list_first_entry(&graveyard, struct vfsmount,
Al Virobcc5c7d2008-03-22 00:21:53 -04001817 mnt_expire);
Eric W. Biedermanafef80b2008-11-12 13:26:54 -08001818 touch_mnt_namespace(m->mnt_ns);
1819 umount_tree(m, 1, umounts);
Al Virobcc5c7d2008-03-22 00:21:53 -04001820 }
1821 }
Trond Myklebust5528f9112006-06-09 09:34:17 -04001822}
1823
Trond Myklebust5528f9112006-06-09 09:34:17 -04001824/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 * Some copy_from_user() implementations do not return the exact number of
1826 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
1827 * Note that this function differs from copy_from_user() in that it will oops
1828 * on bad values of `to', rather than returning a short copy.
1829 */
Ram Paib58fed82005-11-07 17:16:09 -05001830static long exact_copy_from_user(void *to, const void __user * from,
1831 unsigned long n)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832{
1833 char *t = to;
1834 const char __user *f = from;
1835 char c;
1836
1837 if (!access_ok(VERIFY_READ, from, n))
1838 return n;
1839
1840 while (n) {
1841 if (__get_user(c, f)) {
1842 memset(t, 0, n);
1843 break;
1844 }
1845 *t++ = c;
1846 f++;
1847 n--;
1848 }
1849 return n;
1850}
1851
Ram Paib58fed82005-11-07 17:16:09 -05001852int copy_mount_options(const void __user * data, unsigned long *where)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853{
1854 int i;
1855 unsigned long page;
1856 unsigned long size;
Ram Paib58fed82005-11-07 17:16:09 -05001857
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858 *where = 0;
1859 if (!data)
1860 return 0;
1861
1862 if (!(page = __get_free_page(GFP_KERNEL)))
1863 return -ENOMEM;
1864
1865 /* We only care that *some* data at the address the user
1866 * gave us is valid. Just in case, we'll zero
1867 * the remainder of the page.
1868 */
1869 /* copy_from_user cannot cross TASK_SIZE ! */
1870 size = TASK_SIZE - (unsigned long)data;
1871 if (size > PAGE_SIZE)
1872 size = PAGE_SIZE;
1873
1874 i = size - exact_copy_from_user((void *)page, data, size);
1875 if (!i) {
Ram Paib58fed82005-11-07 17:16:09 -05001876 free_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 return -EFAULT;
1878 }
1879 if (i != PAGE_SIZE)
1880 memset((char *)page + i, 0, PAGE_SIZE - i);
1881 *where = page;
1882 return 0;
1883}
1884
1885/*
1886 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
1887 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
1888 *
1889 * data is a (void *) that can point to any structure up to
1890 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
1891 * information (or be NULL).
1892 *
1893 * Pre-0.97 versions of mount() didn't have a flags word.
1894 * When the flags word was introduced its top half was required
1895 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
1896 * Therefore, if this magic number is present, it carries no information
1897 * and must be discarded.
1898 */
Ram Paib58fed82005-11-07 17:16:09 -05001899long do_mount(char *dev_name, char *dir_name, char *type_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900 unsigned long flags, void *data_page)
1901{
Al Viro2d92ab32008-08-02 00:51:11 -04001902 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903 int retval = 0;
1904 int mnt_flags = 0;
1905
1906 /* Discard magic */
1907 if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
1908 flags &= ~MS_MGC_MSK;
1909
1910 /* Basic sanity checks */
1911
1912 if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
1913 return -EINVAL;
1914 if (dev_name && !memchr(dev_name, 0, PAGE_SIZE))
1915 return -EINVAL;
1916
1917 if (data_page)
1918 ((char *)data_page)[PAGE_SIZE - 1] = 0;
1919
1920 /* Separate the per-mountpoint flags */
1921 if (flags & MS_NOSUID)
1922 mnt_flags |= MNT_NOSUID;
1923 if (flags & MS_NODEV)
1924 mnt_flags |= MNT_NODEV;
1925 if (flags & MS_NOEXEC)
1926 mnt_flags |= MNT_NOEXEC;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001927 if (flags & MS_NOATIME)
1928 mnt_flags |= MNT_NOATIME;
1929 if (flags & MS_NODIRATIME)
1930 mnt_flags |= MNT_NODIRATIME;
Valerie Henson47ae32d2006-12-13 00:34:34 -08001931 if (flags & MS_RELATIME)
1932 mnt_flags |= MNT_RELATIME;
Dave Hansen2e4b7fc2008-02-15 14:38:00 -08001933 if (flags & MS_RDONLY)
1934 mnt_flags |= MNT_READONLY;
Christoph Hellwigfc33a7b2006-01-09 20:52:17 -08001935
1936 flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001937 MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938
1939 /* ... and get the mountpoint */
Al Viro2d92ab32008-08-02 00:51:11 -04001940 retval = kern_path(dir_name, LOOKUP_FOLLOW, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941 if (retval)
1942 return retval;
1943
Al Viro2d92ab32008-08-02 00:51:11 -04001944 retval = security_sb_mount(dev_name, &path,
Al Virob5266eb2008-03-22 17:48:24 -04001945 type_page, flags, data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 if (retval)
1947 goto dput_out;
1948
1949 if (flags & MS_REMOUNT)
Al Viro2d92ab32008-08-02 00:51:11 -04001950 retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 data_page);
1952 else if (flags & MS_BIND)
Al Viro2d92ab32008-08-02 00:51:11 -04001953 retval = do_loopback(&path, dev_name, flags & MS_REC);
Ram Pai9676f0c2005-11-07 17:21:20 -05001954 else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
Al Viro2d92ab32008-08-02 00:51:11 -04001955 retval = do_change_type(&path, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956 else if (flags & MS_MOVE)
Al Viro2d92ab32008-08-02 00:51:11 -04001957 retval = do_move_mount(&path, dev_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 else
Al Viro2d92ab32008-08-02 00:51:11 -04001959 retval = do_new_mount(&path, type_page, flags, mnt_flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960 dev_name, data_page);
1961dput_out:
Al Viro2d92ab32008-08-02 00:51:11 -04001962 path_put(&path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 return retval;
1964}
1965
JANAK DESAI741a2952006-02-07 12:59:00 -08001966/*
1967 * Allocate a new namespace structure and populate it with contents
1968 * copied from the namespace of the passed in task structure.
1969 */
Badari Pulavartye3222c42007-05-08 00:25:21 -07001970static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001971 struct fs_struct *fs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001972{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001973 struct mnt_namespace *new_ns;
Al Viro7f2da1e2008-05-10 20:44:54 -04001974 struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001975 struct vfsmount *p, *q;
1976
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001977 new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 if (!new_ns)
Cedric Le Goater467e9f42007-07-15 23:41:06 -07001979 return ERR_PTR(-ENOMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980
1981 atomic_set(&new_ns->count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 INIT_LIST_HEAD(&new_ns->list);
Al Viro5addc5d2005-11-07 17:15:49 -05001983 init_waitqueue_head(&new_ns->poll);
1984 new_ns->event = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985
Ram Pai390c6842005-11-07 17:17:51 -05001986 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987 /* First pass: copy the tree topology */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08001988 new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root,
Ram Pai9676f0c2005-11-07 17:21:20 -05001989 CL_COPY_ALL | CL_EXPIRE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990 if (!new_ns->root) {
Ram Pai390c6842005-11-07 17:17:51 -05001991 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001992 kfree(new_ns);
Julia Lawall5cc4a032008-12-01 14:34:51 -08001993 return ERR_PTR(-ENOMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994 }
1995 spin_lock(&vfsmount_lock);
1996 list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
1997 spin_unlock(&vfsmount_lock);
1998
1999 /*
2000 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
2001 * as belonging to new namespace. We have already acquired a private
2002 * fs_struct, so tsk->fs->lock is not needed.
2003 */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002004 p = mnt_ns->root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005 q = new_ns->root;
2006 while (p) {
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002007 q->mnt_ns = new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008 if (fs) {
Jan Blunck6ac08c32008-02-14 19:34:38 -08002009 if (p == fs->root.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002010 rootmnt = p;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002011 fs->root.mnt = mntget(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012 }
Jan Blunck6ac08c32008-02-14 19:34:38 -08002013 if (p == fs->pwd.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002014 pwdmnt = p;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002015 fs->pwd.mnt = mntget(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017 }
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002018 p = next_mnt(p, mnt_ns->root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019 q = next_mnt(q, new_ns->root);
2020 }
Ram Pai390c6842005-11-07 17:17:51 -05002021 up_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023 if (rootmnt)
2024 mntput(rootmnt);
2025 if (pwdmnt)
2026 mntput(pwdmnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027
JANAK DESAI741a2952006-02-07 12:59:00 -08002028 return new_ns;
2029}
2030
Eric W. Biederman213dd262007-07-15 23:41:15 -07002031struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
Badari Pulavartye3222c42007-05-08 00:25:21 -07002032 struct fs_struct *new_fs)
JANAK DESAI741a2952006-02-07 12:59:00 -08002033{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002034 struct mnt_namespace *new_ns;
JANAK DESAI741a2952006-02-07 12:59:00 -08002035
Badari Pulavartye3222c42007-05-08 00:25:21 -07002036 BUG_ON(!ns);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002037 get_mnt_ns(ns);
JANAK DESAI741a2952006-02-07 12:59:00 -08002038
2039 if (!(flags & CLONE_NEWNS))
Badari Pulavartye3222c42007-05-08 00:25:21 -07002040 return ns;
JANAK DESAI741a2952006-02-07 12:59:00 -08002041
Badari Pulavartye3222c42007-05-08 00:25:21 -07002042 new_ns = dup_mnt_ns(ns, new_fs);
JANAK DESAI741a2952006-02-07 12:59:00 -08002043
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002044 put_mnt_ns(ns);
Badari Pulavartye3222c42007-05-08 00:25:21 -07002045 return new_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002046}
2047
Heiko Carstensbdc480e2009-01-14 14:14:12 +01002048SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
2049 char __user *, type, unsigned long, flags, void __user *, data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050{
2051 int retval;
2052 unsigned long data_page;
2053 unsigned long type_page;
2054 unsigned long dev_page;
2055 char *dir_page;
2056
Ram Paib58fed82005-11-07 17:16:09 -05002057 retval = copy_mount_options(type, &type_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 if (retval < 0)
2059 return retval;
2060
2061 dir_page = getname(dir_name);
2062 retval = PTR_ERR(dir_page);
2063 if (IS_ERR(dir_page))
2064 goto out1;
2065
Ram Paib58fed82005-11-07 17:16:09 -05002066 retval = copy_mount_options(dev_name, &dev_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067 if (retval < 0)
2068 goto out2;
2069
Ram Paib58fed82005-11-07 17:16:09 -05002070 retval = copy_mount_options(data, &data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002071 if (retval < 0)
2072 goto out3;
2073
2074 lock_kernel();
Ram Paib58fed82005-11-07 17:16:09 -05002075 retval = do_mount((char *)dev_page, dir_page, (char *)type_page,
2076 flags, (void *)data_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002077 unlock_kernel();
2078 free_page(data_page);
2079
2080out3:
2081 free_page(dev_page);
2082out2:
2083 putname(dir_page);
2084out1:
2085 free_page(type_page);
2086 return retval;
2087}
2088
2089/*
2090 * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
2091 * It can block. Requires the big lock held.
2092 */
Jan Blunckac748a02008-02-14 19:34:39 -08002093void set_fs_root(struct fs_struct *fs, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094{
Jan Blunck6ac08c32008-02-14 19:34:38 -08002095 struct path old_root;
2096
Linus Torvalds1da177e2005-04-16 15:20:36 -07002097 write_lock(&fs->lock);
2098 old_root = fs->root;
Jan Blunckac748a02008-02-14 19:34:39 -08002099 fs->root = *path;
2100 path_get(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002101 write_unlock(&fs->lock);
Jan Blunck6ac08c32008-02-14 19:34:38 -08002102 if (old_root.dentry)
2103 path_put(&old_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002104}
2105
2106/*
2107 * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
2108 * It can block. Requires the big lock held.
2109 */
Jan Blunckac748a02008-02-14 19:34:39 -08002110void set_fs_pwd(struct fs_struct *fs, struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111{
Jan Blunck6ac08c32008-02-14 19:34:38 -08002112 struct path old_pwd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113
2114 write_lock(&fs->lock);
2115 old_pwd = fs->pwd;
Jan Blunckac748a02008-02-14 19:34:39 -08002116 fs->pwd = *path;
2117 path_get(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118 write_unlock(&fs->lock);
2119
Jan Blunck6ac08c32008-02-14 19:34:38 -08002120 if (old_pwd.dentry)
2121 path_put(&old_pwd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002122}
2123
Al Viro1a390682008-03-21 20:48:19 -04002124static void chroot_fs_refs(struct path *old_root, struct path *new_root)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125{
2126 struct task_struct *g, *p;
2127 struct fs_struct *fs;
2128
2129 read_lock(&tasklist_lock);
2130 do_each_thread(g, p) {
2131 task_lock(p);
2132 fs = p->fs;
2133 if (fs) {
2134 atomic_inc(&fs->count);
2135 task_unlock(p);
Al Viro1a390682008-03-21 20:48:19 -04002136 if (fs->root.dentry == old_root->dentry
2137 && fs->root.mnt == old_root->mnt)
2138 set_fs_root(fs, new_root);
2139 if (fs->pwd.dentry == old_root->dentry
2140 && fs->pwd.mnt == old_root->mnt)
2141 set_fs_pwd(fs, new_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142 put_fs_struct(fs);
2143 } else
2144 task_unlock(p);
2145 } while_each_thread(g, p);
2146 read_unlock(&tasklist_lock);
2147}
2148
2149/*
2150 * pivot_root Semantics:
2151 * Moves the root file system of the current process to the directory put_old,
2152 * makes new_root as the new root file system of the current process, and sets
2153 * root/cwd of all processes which had them on the current root to new_root.
2154 *
2155 * Restrictions:
2156 * The new_root and put_old must be directories, and must not be on the
2157 * same file system as the current process root. The put_old must be
2158 * underneath new_root, i.e. adding a non-zero number of /.. to the string
2159 * pointed to by put_old must yield the same directory as new_root. No other
2160 * file system may be mounted on put_old. After all, new_root is a mountpoint.
2161 *
Neil Brown4a0d11f2006-01-08 01:03:18 -08002162 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
2163 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
2164 * in this situation.
2165 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166 * Notes:
2167 * - we don't move root/cwd if they are not at the root (reason: if something
2168 * cared enough to change them, it's probably wrong to force them elsewhere)
2169 * - it's okay to pick a root that isn't the root of a file system, e.g.
2170 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
2171 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
2172 * first.
2173 */
Heiko Carstens3480b252009-01-14 14:14:16 +01002174SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
2175 const char __user *, put_old)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176{
2177 struct vfsmount *tmp;
Al Viro2d8f3032008-07-22 09:59:21 -04002178 struct path new, old, parent_path, root_parent, root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 int error;
2180
2181 if (!capable(CAP_SYS_ADMIN))
2182 return -EPERM;
2183
Al Viro2d8f3032008-07-22 09:59:21 -04002184 error = user_path_dir(new_root, &new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185 if (error)
2186 goto out0;
2187 error = -EINVAL;
Al Viro2d8f3032008-07-22 09:59:21 -04002188 if (!check_mnt(new.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189 goto out1;
2190
Al Viro2d8f3032008-07-22 09:59:21 -04002191 error = user_path_dir(put_old, &old);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 if (error)
2193 goto out1;
2194
Al Viro2d8f3032008-07-22 09:59:21 -04002195 error = security_sb_pivotroot(&old, &new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196 if (error) {
Al Viro2d8f3032008-07-22 09:59:21 -04002197 path_put(&old);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198 goto out1;
2199 }
2200
2201 read_lock(&current->fs->lock);
Al Viro8c3ee422008-03-22 18:00:39 -04002202 root = current->fs->root;
Jan Blunck6ac08c32008-02-14 19:34:38 -08002203 path_get(&current->fs->root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204 read_unlock(&current->fs->lock);
Ram Pai390c6842005-11-07 17:17:51 -05002205 down_write(&namespace_sem);
Al Viro2d8f3032008-07-22 09:59:21 -04002206 mutex_lock(&old.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 error = -EINVAL;
Al Viro2d8f3032008-07-22 09:59:21 -04002208 if (IS_MNT_SHARED(old.mnt) ||
2209 IS_MNT_SHARED(new.mnt->mnt_parent) ||
Al Viro8c3ee422008-03-22 18:00:39 -04002210 IS_MNT_SHARED(root.mnt->mnt_parent))
Ram Pai21444402005-11-07 17:20:03 -05002211 goto out2;
Al Viro8c3ee422008-03-22 18:00:39 -04002212 if (!check_mnt(root.mnt))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002213 goto out2;
2214 error = -ENOENT;
Al Viro2d8f3032008-07-22 09:59:21 -04002215 if (IS_DEADDIR(new.dentry->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216 goto out2;
Al Viro2d8f3032008-07-22 09:59:21 -04002217 if (d_unhashed(new.dentry) && !IS_ROOT(new.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218 goto out2;
Al Viro2d8f3032008-07-22 09:59:21 -04002219 if (d_unhashed(old.dentry) && !IS_ROOT(old.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 goto out2;
2221 error = -EBUSY;
Al Viro2d8f3032008-07-22 09:59:21 -04002222 if (new.mnt == root.mnt ||
2223 old.mnt == root.mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224 goto out2; /* loop, on the same file system */
2225 error = -EINVAL;
Al Viro8c3ee422008-03-22 18:00:39 -04002226 if (root.mnt->mnt_root != root.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227 goto out2; /* not a mountpoint */
Al Viro8c3ee422008-03-22 18:00:39 -04002228 if (root.mnt->mnt_parent == root.mnt)
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07002229 goto out2; /* not attached */
Al Viro2d8f3032008-07-22 09:59:21 -04002230 if (new.mnt->mnt_root != new.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231 goto out2; /* not a mountpoint */
Al Viro2d8f3032008-07-22 09:59:21 -04002232 if (new.mnt->mnt_parent == new.mnt)
Miklos Szeredi0bb6fcc2005-09-06 15:19:36 -07002233 goto out2; /* not attached */
Jan Blunck4ac91372008-02-14 19:34:32 -08002234 /* make sure we can reach put_old from new_root */
Al Viro2d8f3032008-07-22 09:59:21 -04002235 tmp = old.mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002236 spin_lock(&vfsmount_lock);
Al Viro2d8f3032008-07-22 09:59:21 -04002237 if (tmp != new.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 for (;;) {
2239 if (tmp->mnt_parent == tmp)
2240 goto out3; /* already mounted on put_old */
Al Viro2d8f3032008-07-22 09:59:21 -04002241 if (tmp->mnt_parent == new.mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002242 break;
2243 tmp = tmp->mnt_parent;
2244 }
Al Viro2d8f3032008-07-22 09:59:21 -04002245 if (!is_subdir(tmp->mnt_mountpoint, new.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002246 goto out3;
Al Viro2d8f3032008-07-22 09:59:21 -04002247 } else if (!is_subdir(old.dentry, new.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 goto out3;
Al Viro2d8f3032008-07-22 09:59:21 -04002249 detach_mnt(new.mnt, &parent_path);
Al Viro8c3ee422008-03-22 18:00:39 -04002250 detach_mnt(root.mnt, &root_parent);
Jan Blunck4ac91372008-02-14 19:34:32 -08002251 /* mount old root on put_old */
Al Viro2d8f3032008-07-22 09:59:21 -04002252 attach_mnt(root.mnt, &old);
Jan Blunck4ac91372008-02-14 19:34:32 -08002253 /* mount new_root on / */
Al Viro2d8f3032008-07-22 09:59:21 -04002254 attach_mnt(new.mnt, &root_parent);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002255 touch_mnt_namespace(current->nsproxy->mnt_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256 spin_unlock(&vfsmount_lock);
Al Viro2d8f3032008-07-22 09:59:21 -04002257 chroot_fs_refs(&root, &new);
2258 security_sb_post_pivotroot(&root, &new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002259 error = 0;
Al Viro1a390682008-03-21 20:48:19 -04002260 path_put(&root_parent);
2261 path_put(&parent_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262out2:
Al Viro2d8f3032008-07-22 09:59:21 -04002263 mutex_unlock(&old.dentry->d_inode->i_mutex);
Ram Pai390c6842005-11-07 17:17:51 -05002264 up_write(&namespace_sem);
Al Viro8c3ee422008-03-22 18:00:39 -04002265 path_put(&root);
Al Viro2d8f3032008-07-22 09:59:21 -04002266 path_put(&old);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267out1:
Al Viro2d8f3032008-07-22 09:59:21 -04002268 path_put(&new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269out0:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 return error;
2271out3:
2272 spin_unlock(&vfsmount_lock);
2273 goto out2;
2274}
2275
2276static void __init init_mount_tree(void)
2277{
2278 struct vfsmount *mnt;
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002279 struct mnt_namespace *ns;
Jan Blunckac748a02008-02-14 19:34:39 -08002280 struct path root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002281
2282 mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
2283 if (IS_ERR(mnt))
2284 panic("Can't create rootfs");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002285 ns = kmalloc(sizeof(*ns), GFP_KERNEL);
2286 if (!ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002287 panic("Can't allocate initial namespace");
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002288 atomic_set(&ns->count, 1);
2289 INIT_LIST_HEAD(&ns->list);
2290 init_waitqueue_head(&ns->poll);
2291 ns->event = 0;
2292 list_add(&mnt->mnt_list, &ns->list);
2293 ns->root = mnt;
2294 mnt->mnt_ns = ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002296 init_task.nsproxy->mnt_ns = ns;
2297 get_mnt_ns(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002298
Jan Blunckac748a02008-02-14 19:34:39 -08002299 root.mnt = ns->root;
2300 root.dentry = ns->root->mnt_root;
2301
2302 set_fs_pwd(current->fs, &root);
2303 set_fs_root(current->fs, &root);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304}
2305
Denis Cheng74bf17c2007-10-16 23:26:30 -07002306void __init mnt_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002307{
Eric Dumazet13f14b42008-02-06 01:37:57 -08002308 unsigned u;
Randy Dunlap15a67dd2006-09-29 01:58:57 -07002309 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002310
Ram Pai390c6842005-11-07 17:17:51 -05002311 init_rwsem(&namespace_sem);
2312
Linus Torvalds1da177e2005-04-16 15:20:36 -07002313 mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
Paul Mundt20c2df82007-07-20 10:11:58 +09002314 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002315
Ram Paib58fed82005-11-07 17:16:09 -05002316 mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002317
2318 if (!mount_hashtable)
2319 panic("Failed to allocate mount hash table\n");
2320
Eric Dumazet13f14b42008-02-06 01:37:57 -08002321 printk("Mount-cache hash table entries: %lu\n", HASH_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002322
Eric Dumazet13f14b42008-02-06 01:37:57 -08002323 for (u = 0; u < HASH_SIZE; u++)
2324 INIT_LIST_HEAD(&mount_hashtable[u]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325
Randy Dunlap15a67dd2006-09-29 01:58:57 -07002326 err = sysfs_init();
2327 if (err)
2328 printk(KERN_WARNING "%s: sysfs_init error: %d\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -07002329 __func__, err);
Greg Kroah-Hartman00d26662007-10-29 14:17:23 -06002330 fs_kobj = kobject_create_and_add("fs", NULL);
2331 if (!fs_kobj)
Harvey Harrison8e24eea2008-04-30 00:55:09 -07002332 printk(KERN_WARNING "%s: kobj create error\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333 init_rootfs();
2334 init_mount_tree();
2335}
2336
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002337void __put_mnt_ns(struct mnt_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338{
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002339 struct vfsmount *root = ns->root;
Ram Pai70fbcdf2005-11-07 17:17:04 -05002340 LIST_HEAD(umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002341 ns->root = NULL;
Miklos Szeredi1ce88cf2005-07-07 17:57:24 -07002342 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05002343 down_write(&namespace_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002344 spin_lock(&vfsmount_lock);
Ram Paia05964f2005-11-07 17:20:17 -05002345 umount_tree(root, 0, &umount_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002346 spin_unlock(&vfsmount_lock);
Ram Pai390c6842005-11-07 17:17:51 -05002347 up_write(&namespace_sem);
Ram Pai70fbcdf2005-11-07 17:17:04 -05002348 release_mounts(&umount_list);
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08002349 kfree(ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002350}