MIPS: Don't write ones to reserved entryhi bits.
[linux-2.6/linux-2.6-openrd.git] / fs / namespace.c
blobbdc3cb4fd2220c6fde0f35159a902768a75d60f6
1 /*
2 * linux/fs/namespace.c
4 * (C) Copyright Al Viro 2000, 2001
5 * Released under GPL v2.
7 * Based on code from fs/super.c, copyright Linus Torvalds and others.
8 * Heavily rewritten.
9 */
11 #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>
16 #include <linux/kernel.h>
17 #include <linux/acct.h>
18 #include <linux/capability.h>
19 #include <linux/cpumask.h>
20 #include <linux/module.h>
21 #include <linux/sysfs.h>
22 #include <linux/seq_file.h>
23 #include <linux/mnt_namespace.h>
24 #include <linux/namei.h>
25 #include <linux/nsproxy.h>
26 #include <linux/security.h>
27 #include <linux/mount.h>
28 #include <linux/ramfs.h>
29 #include <linux/log2.h>
30 #include <linux/idr.h>
31 #include <linux/fs_struct.h>
32 #include <asm/uaccess.h>
33 #include <asm/unistd.h>
34 #include "pnode.h"
35 #include "internal.h"
37 #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head))
38 #define HASH_SIZE (1UL << HASH_SHIFT)
40 /* spinlock for vfsmount related operations, inplace of dcache_lock */
41 __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
43 static int event;
44 static DEFINE_IDA(mnt_id_ida);
45 static DEFINE_IDA(mnt_group_ida);
46 static int mnt_id_start = 0;
47 static int mnt_group_start = 1;
49 static struct list_head *mount_hashtable __read_mostly;
50 static struct kmem_cache *mnt_cache __read_mostly;
51 static struct rw_semaphore namespace_sem;
53 /* /sys/fs */
54 struct kobject *fs_kobj;
55 EXPORT_SYMBOL_GPL(fs_kobj);
57 static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
59 unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
60 tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
61 tmp = tmp + (tmp >> HASH_SHIFT);
62 return tmp & (HASH_SIZE - 1);
65 #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16)
67 /* allocation is serialized by namespace_sem */
68 static int mnt_alloc_id(struct vfsmount *mnt)
70 int res;
72 retry:
73 ida_pre_get(&mnt_id_ida, GFP_KERNEL);
74 spin_lock(&vfsmount_lock);
75 res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id);
76 if (!res)
77 mnt_id_start = mnt->mnt_id + 1;
78 spin_unlock(&vfsmount_lock);
79 if (res == -EAGAIN)
80 goto retry;
82 return res;
85 static void mnt_free_id(struct vfsmount *mnt)
87 int id = mnt->mnt_id;
88 spin_lock(&vfsmount_lock);
89 ida_remove(&mnt_id_ida, id);
90 if (mnt_id_start > id)
91 mnt_id_start = id;
92 spin_unlock(&vfsmount_lock);
96 * Allocate a new peer group ID
98 * mnt_group_ida is protected by namespace_sem
100 static int mnt_alloc_group_id(struct vfsmount *mnt)
102 int res;
104 if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL))
105 return -ENOMEM;
107 res = ida_get_new_above(&mnt_group_ida,
108 mnt_group_start,
109 &mnt->mnt_group_id);
110 if (!res)
111 mnt_group_start = mnt->mnt_group_id + 1;
113 return res;
117 * Release a peer group ID
119 void mnt_release_group_id(struct vfsmount *mnt)
121 int id = mnt->mnt_group_id;
122 ida_remove(&mnt_group_ida, id);
123 if (mnt_group_start > id)
124 mnt_group_start = id;
125 mnt->mnt_group_id = 0;
128 struct vfsmount *alloc_vfsmnt(const char *name)
130 struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
131 if (mnt) {
132 int err;
134 err = mnt_alloc_id(mnt);
135 if (err)
136 goto out_free_cache;
138 if (name) {
139 mnt->mnt_devname = kstrdup(name, GFP_KERNEL);
140 if (!mnt->mnt_devname)
141 goto out_free_id;
144 atomic_set(&mnt->mnt_count, 1);
145 INIT_LIST_HEAD(&mnt->mnt_hash);
146 INIT_LIST_HEAD(&mnt->mnt_child);
147 INIT_LIST_HEAD(&mnt->mnt_mounts);
148 INIT_LIST_HEAD(&mnt->mnt_list);
149 INIT_LIST_HEAD(&mnt->mnt_expire);
150 INIT_LIST_HEAD(&mnt->mnt_share);
151 INIT_LIST_HEAD(&mnt->mnt_slave_list);
152 INIT_LIST_HEAD(&mnt->mnt_slave);
153 #ifdef CONFIG_SMP
154 mnt->mnt_writers = alloc_percpu(int);
155 if (!mnt->mnt_writers)
156 goto out_free_devname;
157 #else
158 mnt->mnt_writers = 0;
159 #endif
161 return mnt;
163 #ifdef CONFIG_SMP
164 out_free_devname:
165 kfree(mnt->mnt_devname);
166 #endif
167 out_free_id:
168 mnt_free_id(mnt);
169 out_free_cache:
170 kmem_cache_free(mnt_cache, mnt);
171 return NULL;
175 * Most r/o checks on a fs are for operations that take
176 * discrete amounts of time, like a write() or unlink().
177 * We must keep track of when those operations start
178 * (for permission checks) and when they end, so that
179 * we can determine when writes are able to occur to
180 * a filesystem.
183 * __mnt_is_readonly: check whether a mount is read-only
184 * @mnt: the mount to check for its write status
186 * This shouldn't be used directly ouside of the VFS.
187 * It does not guarantee that the filesystem will stay
188 * r/w, just that it is right *now*. This can not and
189 * should not be used in place of IS_RDONLY(inode).
190 * mnt_want/drop_write() will _keep_ the filesystem
191 * r/w.
193 int __mnt_is_readonly(struct vfsmount *mnt)
195 if (mnt->mnt_flags & MNT_READONLY)
196 return 1;
197 if (mnt->mnt_sb->s_flags & MS_RDONLY)
198 return 1;
199 return 0;
201 EXPORT_SYMBOL_GPL(__mnt_is_readonly);
203 static inline void inc_mnt_writers(struct vfsmount *mnt)
205 #ifdef CONFIG_SMP
206 (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))++;
207 #else
208 mnt->mnt_writers++;
209 #endif
212 static inline void dec_mnt_writers(struct vfsmount *mnt)
214 #ifdef CONFIG_SMP
215 (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))--;
216 #else
217 mnt->mnt_writers--;
218 #endif
221 static unsigned int count_mnt_writers(struct vfsmount *mnt)
223 #ifdef CONFIG_SMP
224 unsigned int count = 0;
225 int cpu;
227 for_each_possible_cpu(cpu) {
228 count += *per_cpu_ptr(mnt->mnt_writers, cpu);
231 return count;
232 #else
233 return mnt->mnt_writers;
234 #endif
238 * Most r/o checks on a fs are for operations that take
239 * discrete amounts of time, like a write() or unlink().
240 * We must keep track of when those operations start
241 * (for permission checks) and when they end, so that
242 * we can determine when writes are able to occur to
243 * a filesystem.
246 * mnt_want_write - get write access to a mount
247 * @mnt: the mount on which to take a write
249 * This tells the low-level filesystem that a write is
250 * about to be performed to it, and makes sure that
251 * writes are allowed before returning success. When
252 * the write operation is finished, mnt_drop_write()
253 * must be called. This is effectively a refcount.
255 int mnt_want_write(struct vfsmount *mnt)
257 int ret = 0;
259 preempt_disable();
260 inc_mnt_writers(mnt);
262 * The store to inc_mnt_writers must be visible before we pass
263 * MNT_WRITE_HOLD loop below, so that the slowpath can see our
264 * incremented count after it has set MNT_WRITE_HOLD.
266 smp_mb();
267 while (mnt->mnt_flags & MNT_WRITE_HOLD)
268 cpu_relax();
270 * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
271 * be set to match its requirements. So we must not load that until
272 * MNT_WRITE_HOLD is cleared.
274 smp_rmb();
275 if (__mnt_is_readonly(mnt)) {
276 dec_mnt_writers(mnt);
277 ret = -EROFS;
278 goto out;
280 out:
281 preempt_enable();
282 return ret;
284 EXPORT_SYMBOL_GPL(mnt_want_write);
287 * mnt_clone_write - get write access to a mount
288 * @mnt: the mount on which to take a write
290 * This is effectively like mnt_want_write, except
291 * it must only be used to take an extra write reference
292 * on a mountpoint that we already know has a write reference
293 * on it. This allows some optimisation.
295 * After finished, mnt_drop_write must be called as usual to
296 * drop the reference.
298 int mnt_clone_write(struct vfsmount *mnt)
300 /* superblock may be r/o */
301 if (__mnt_is_readonly(mnt))
302 return -EROFS;
303 preempt_disable();
304 inc_mnt_writers(mnt);
305 preempt_enable();
306 return 0;
308 EXPORT_SYMBOL_GPL(mnt_clone_write);
311 * mnt_want_write_file - get write access to a file's mount
312 * @file: the file who's mount on which to take a write
314 * This is like mnt_want_write, but it takes a file and can
315 * do some optimisations if the file is open for write already
317 int mnt_want_write_file(struct file *file)
319 struct inode *inode = file->f_dentry->d_inode;
320 if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode))
321 return mnt_want_write(file->f_path.mnt);
322 else
323 return mnt_clone_write(file->f_path.mnt);
325 EXPORT_SYMBOL_GPL(mnt_want_write_file);
328 * mnt_drop_write - give up write access to a mount
329 * @mnt: the mount on which to give up write access
331 * Tells the low-level filesystem that we are done
332 * performing writes to it. Must be matched with
333 * mnt_want_write() call above.
335 void mnt_drop_write(struct vfsmount *mnt)
337 preempt_disable();
338 dec_mnt_writers(mnt);
339 preempt_enable();
341 EXPORT_SYMBOL_GPL(mnt_drop_write);
343 static int mnt_make_readonly(struct vfsmount *mnt)
345 int ret = 0;
347 spin_lock(&vfsmount_lock);
348 mnt->mnt_flags |= MNT_WRITE_HOLD;
350 * After storing MNT_WRITE_HOLD, we'll read the counters. This store
351 * should be visible before we do.
353 smp_mb();
356 * With writers on hold, if this value is zero, then there are
357 * definitely no active writers (although held writers may subsequently
358 * increment the count, they'll have to wait, and decrement it after
359 * seeing MNT_READONLY).
361 * It is OK to have counter incremented on one CPU and decremented on
362 * another: the sum will add up correctly. The danger would be when we
363 * sum up each counter, if we read a counter before it is incremented,
364 * but then read another CPU's count which it has been subsequently
365 * decremented from -- we would see more decrements than we should.
366 * MNT_WRITE_HOLD protects against this scenario, because
367 * mnt_want_write first increments count, then smp_mb, then spins on
368 * MNT_WRITE_HOLD, so it can't be decremented by another CPU while
369 * we're counting up here.
371 if (count_mnt_writers(mnt) > 0)
372 ret = -EBUSY;
373 else
374 mnt->mnt_flags |= MNT_READONLY;
376 * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
377 * that become unheld will see MNT_READONLY.
379 smp_wmb();
380 mnt->mnt_flags &= ~MNT_WRITE_HOLD;
381 spin_unlock(&vfsmount_lock);
382 return ret;
385 static void __mnt_unmake_readonly(struct vfsmount *mnt)
387 spin_lock(&vfsmount_lock);
388 mnt->mnt_flags &= ~MNT_READONLY;
389 spin_unlock(&vfsmount_lock);
392 void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
394 mnt->mnt_sb = sb;
395 mnt->mnt_root = dget(sb->s_root);
398 EXPORT_SYMBOL(simple_set_mnt);
400 void free_vfsmnt(struct vfsmount *mnt)
402 kfree(mnt->mnt_devname);
403 mnt_free_id(mnt);
404 #ifdef CONFIG_SMP
405 free_percpu(mnt->mnt_writers);
406 #endif
407 kmem_cache_free(mnt_cache, mnt);
411 * find the first or last mount at @dentry on vfsmount @mnt depending on
412 * @dir. If @dir is set return the first mount else return the last mount.
414 struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
415 int dir)
417 struct list_head *head = mount_hashtable + hash(mnt, dentry);
418 struct list_head *tmp = head;
419 struct vfsmount *p, *found = NULL;
421 for (;;) {
422 tmp = dir ? tmp->next : tmp->prev;
423 p = NULL;
424 if (tmp == head)
425 break;
426 p = list_entry(tmp, struct vfsmount, mnt_hash);
427 if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
428 found = p;
429 break;
432 return found;
436 * lookup_mnt increments the ref count before returning
437 * the vfsmount struct.
439 struct vfsmount *lookup_mnt(struct path *path)
441 struct vfsmount *child_mnt;
442 spin_lock(&vfsmount_lock);
443 if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1)))
444 mntget(child_mnt);
445 spin_unlock(&vfsmount_lock);
446 return child_mnt;
449 static inline int check_mnt(struct vfsmount *mnt)
451 return mnt->mnt_ns == current->nsproxy->mnt_ns;
454 static void touch_mnt_namespace(struct mnt_namespace *ns)
456 if (ns) {
457 ns->event = ++event;
458 wake_up_interruptible(&ns->poll);
462 static void __touch_mnt_namespace(struct mnt_namespace *ns)
464 if (ns && ns->event != event) {
465 ns->event = event;
466 wake_up_interruptible(&ns->poll);
470 static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
472 old_path->dentry = mnt->mnt_mountpoint;
473 old_path->mnt = mnt->mnt_parent;
474 mnt->mnt_parent = mnt;
475 mnt->mnt_mountpoint = mnt->mnt_root;
476 list_del_init(&mnt->mnt_child);
477 list_del_init(&mnt->mnt_hash);
478 old_path->dentry->d_mounted--;
481 void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
482 struct vfsmount *child_mnt)
484 child_mnt->mnt_parent = mntget(mnt);
485 child_mnt->mnt_mountpoint = dget(dentry);
486 dentry->d_mounted++;
489 static void attach_mnt(struct vfsmount *mnt, struct path *path)
491 mnt_set_mountpoint(path->mnt, path->dentry, mnt);
492 list_add_tail(&mnt->mnt_hash, mount_hashtable +
493 hash(path->mnt, path->dentry));
494 list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
498 * the caller must hold vfsmount_lock
500 static void commit_tree(struct vfsmount *mnt)
502 struct vfsmount *parent = mnt->mnt_parent;
503 struct vfsmount *m;
504 LIST_HEAD(head);
505 struct mnt_namespace *n = parent->mnt_ns;
507 BUG_ON(parent == mnt);
509 list_add_tail(&head, &mnt->mnt_list);
510 list_for_each_entry(m, &head, mnt_list)
511 m->mnt_ns = n;
512 list_splice(&head, n->list.prev);
514 list_add_tail(&mnt->mnt_hash, mount_hashtable +
515 hash(parent, mnt->mnt_mountpoint));
516 list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
517 touch_mnt_namespace(n);
520 static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
522 struct list_head *next = p->mnt_mounts.next;
523 if (next == &p->mnt_mounts) {
524 while (1) {
525 if (p == root)
526 return NULL;
527 next = p->mnt_child.next;
528 if (next != &p->mnt_parent->mnt_mounts)
529 break;
530 p = p->mnt_parent;
533 return list_entry(next, struct vfsmount, mnt_child);
536 static struct vfsmount *skip_mnt_tree(struct vfsmount *p)
538 struct list_head *prev = p->mnt_mounts.prev;
539 while (prev != &p->mnt_mounts) {
540 p = list_entry(prev, struct vfsmount, mnt_child);
541 prev = p->mnt_mounts.prev;
543 return p;
546 static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
547 int flag)
549 struct super_block *sb = old->mnt_sb;
550 struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
552 if (mnt) {
553 if (flag & (CL_SLAVE | CL_PRIVATE))
554 mnt->mnt_group_id = 0; /* not a peer of original */
555 else
556 mnt->mnt_group_id = old->mnt_group_id;
558 if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
559 int err = mnt_alloc_group_id(mnt);
560 if (err)
561 goto out_free;
564 mnt->mnt_flags = old->mnt_flags;
565 atomic_inc(&sb->s_active);
566 mnt->mnt_sb = sb;
567 mnt->mnt_root = dget(root);
568 mnt->mnt_mountpoint = mnt->mnt_root;
569 mnt->mnt_parent = mnt;
571 if (flag & CL_SLAVE) {
572 list_add(&mnt->mnt_slave, &old->mnt_slave_list);
573 mnt->mnt_master = old;
574 CLEAR_MNT_SHARED(mnt);
575 } else if (!(flag & CL_PRIVATE)) {
576 if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
577 list_add(&mnt->mnt_share, &old->mnt_share);
578 if (IS_MNT_SLAVE(old))
579 list_add(&mnt->mnt_slave, &old->mnt_slave);
580 mnt->mnt_master = old->mnt_master;
582 if (flag & CL_MAKE_SHARED)
583 set_mnt_shared(mnt);
585 /* stick the duplicate mount on the same expiry list
586 * as the original if that was on one */
587 if (flag & CL_EXPIRE) {
588 if (!list_empty(&old->mnt_expire))
589 list_add(&mnt->mnt_expire, &old->mnt_expire);
592 return mnt;
594 out_free:
595 free_vfsmnt(mnt);
596 return NULL;
599 static inline void __mntput(struct vfsmount *mnt)
601 struct super_block *sb = mnt->mnt_sb;
603 * This probably indicates that somebody messed
604 * up a mnt_want/drop_write() pair. If this
605 * happens, the filesystem was probably unable
606 * to make r/w->r/o transitions.
609 * atomic_dec_and_lock() used to deal with ->mnt_count decrements
610 * provides barriers, so count_mnt_writers() below is safe. AV
612 WARN_ON(count_mnt_writers(mnt));
613 dput(mnt->mnt_root);
614 free_vfsmnt(mnt);
615 deactivate_super(sb);
618 void mntput_no_expire(struct vfsmount *mnt)
620 repeat:
621 if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) {
622 if (likely(!mnt->mnt_pinned)) {
623 spin_unlock(&vfsmount_lock);
624 __mntput(mnt);
625 return;
627 atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
628 mnt->mnt_pinned = 0;
629 spin_unlock(&vfsmount_lock);
630 acct_auto_close_mnt(mnt);
631 security_sb_umount_close(mnt);
632 goto repeat;
636 EXPORT_SYMBOL(mntput_no_expire);
638 void mnt_pin(struct vfsmount *mnt)
640 spin_lock(&vfsmount_lock);
641 mnt->mnt_pinned++;
642 spin_unlock(&vfsmount_lock);
645 EXPORT_SYMBOL(mnt_pin);
647 void mnt_unpin(struct vfsmount *mnt)
649 spin_lock(&vfsmount_lock);
650 if (mnt->mnt_pinned) {
651 atomic_inc(&mnt->mnt_count);
652 mnt->mnt_pinned--;
654 spin_unlock(&vfsmount_lock);
657 EXPORT_SYMBOL(mnt_unpin);
659 static inline void mangle(struct seq_file *m, const char *s)
661 seq_escape(m, s, " \t\n\\");
665 * Simple .show_options callback for filesystems which don't want to
666 * implement more complex mount option showing.
668 * See also save_mount_options().
670 int generic_show_options(struct seq_file *m, struct vfsmount *mnt)
672 const char *options;
674 rcu_read_lock();
675 options = rcu_dereference(mnt->mnt_sb->s_options);
677 if (options != NULL && options[0]) {
678 seq_putc(m, ',');
679 mangle(m, options);
681 rcu_read_unlock();
683 return 0;
685 EXPORT_SYMBOL(generic_show_options);
688 * If filesystem uses generic_show_options(), this function should be
689 * called from the fill_super() callback.
691 * The .remount_fs callback usually needs to be handled in a special
692 * way, to make sure, that previous options are not overwritten if the
693 * remount fails.
695 * Also note, that if the filesystem's .remount_fs function doesn't
696 * reset all options to their default value, but changes only newly
697 * given options, then the displayed options will not reflect reality
698 * any more.
700 void save_mount_options(struct super_block *sb, char *options)
702 BUG_ON(sb->s_options);
703 rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL));
705 EXPORT_SYMBOL(save_mount_options);
707 void replace_mount_options(struct super_block *sb, char *options)
709 char *old = sb->s_options;
710 rcu_assign_pointer(sb->s_options, options);
711 if (old) {
712 synchronize_rcu();
713 kfree(old);
716 EXPORT_SYMBOL(replace_mount_options);
718 #ifdef CONFIG_PROC_FS
719 /* iterator */
720 static void *m_start(struct seq_file *m, loff_t *pos)
722 struct proc_mounts *p = m->private;
724 down_read(&namespace_sem);
725 return seq_list_start(&p->ns->list, *pos);
728 static void *m_next(struct seq_file *m, void *v, loff_t *pos)
730 struct proc_mounts *p = m->private;
732 return seq_list_next(v, &p->ns->list, pos);
735 static void m_stop(struct seq_file *m, void *v)
737 up_read(&namespace_sem);
740 struct proc_fs_info {
741 int flag;
742 const char *str;
745 static int show_sb_opts(struct seq_file *m, struct super_block *sb)
747 static const struct proc_fs_info fs_info[] = {
748 { MS_SYNCHRONOUS, ",sync" },
749 { MS_DIRSYNC, ",dirsync" },
750 { MS_MANDLOCK, ",mand" },
751 { 0, NULL }
753 const struct proc_fs_info *fs_infop;
755 for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
756 if (sb->s_flags & fs_infop->flag)
757 seq_puts(m, fs_infop->str);
760 return security_sb_show_options(m, sb);
763 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
765 static const struct proc_fs_info mnt_info[] = {
766 { MNT_NOSUID, ",nosuid" },
767 { MNT_NODEV, ",nodev" },
768 { MNT_NOEXEC, ",noexec" },
769 { MNT_NOATIME, ",noatime" },
770 { MNT_NODIRATIME, ",nodiratime" },
771 { MNT_RELATIME, ",relatime" },
772 { MNT_STRICTATIME, ",strictatime" },
773 { 0, NULL }
775 const struct proc_fs_info *fs_infop;
777 for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
778 if (mnt->mnt_flags & fs_infop->flag)
779 seq_puts(m, fs_infop->str);
783 static void show_type(struct seq_file *m, struct super_block *sb)
785 mangle(m, sb->s_type->name);
786 if (sb->s_subtype && sb->s_subtype[0]) {
787 seq_putc(m, '.');
788 mangle(m, sb->s_subtype);
792 static int show_vfsmnt(struct seq_file *m, void *v)
794 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
795 int err = 0;
796 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
798 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
799 seq_putc(m, ' ');
800 seq_path(m, &mnt_path, " \t\n\\");
801 seq_putc(m, ' ');
802 show_type(m, mnt->mnt_sb);
803 seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
804 err = show_sb_opts(m, mnt->mnt_sb);
805 if (err)
806 goto out;
807 show_mnt_opts(m, mnt);
808 if (mnt->mnt_sb->s_op->show_options)
809 err = mnt->mnt_sb->s_op->show_options(m, mnt);
810 seq_puts(m, " 0 0\n");
811 out:
812 return err;
815 const struct seq_operations mounts_op = {
816 .start = m_start,
817 .next = m_next,
818 .stop = m_stop,
819 .show = show_vfsmnt
822 static int show_mountinfo(struct seq_file *m, void *v)
824 struct proc_mounts *p = m->private;
825 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
826 struct super_block *sb = mnt->mnt_sb;
827 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
828 struct path root = p->root;
829 int err = 0;
831 seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
832 MAJOR(sb->s_dev), MINOR(sb->s_dev));
833 seq_dentry(m, mnt->mnt_root, " \t\n\\");
834 seq_putc(m, ' ');
835 seq_path_root(m, &mnt_path, &root, " \t\n\\");
836 if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
838 * Mountpoint is outside root, discard that one. Ugly,
839 * but less so than trying to do that in iterator in a
840 * race-free way (due to renames).
842 return SEQ_SKIP;
844 seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
845 show_mnt_opts(m, mnt);
847 /* Tagged fields ("foo:X" or "bar") */
848 if (IS_MNT_SHARED(mnt))
849 seq_printf(m, " shared:%i", mnt->mnt_group_id);
850 if (IS_MNT_SLAVE(mnt)) {
851 int master = mnt->mnt_master->mnt_group_id;
852 int dom = get_dominating_id(mnt, &p->root);
853 seq_printf(m, " master:%i", master);
854 if (dom && dom != master)
855 seq_printf(m, " propagate_from:%i", dom);
857 if (IS_MNT_UNBINDABLE(mnt))
858 seq_puts(m, " unbindable");
860 /* Filesystem specific data */
861 seq_puts(m, " - ");
862 show_type(m, sb);
863 seq_putc(m, ' ');
864 mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
865 seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
866 err = show_sb_opts(m, sb);
867 if (err)
868 goto out;
869 if (sb->s_op->show_options)
870 err = sb->s_op->show_options(m, mnt);
871 seq_putc(m, '\n');
872 out:
873 return err;
876 const struct seq_operations mountinfo_op = {
877 .start = m_start,
878 .next = m_next,
879 .stop = m_stop,
880 .show = show_mountinfo,
883 static int show_vfsstat(struct seq_file *m, void *v)
885 struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
886 struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
887 int err = 0;
889 /* device */
890 if (mnt->mnt_devname) {
891 seq_puts(m, "device ");
892 mangle(m, mnt->mnt_devname);
893 } else
894 seq_puts(m, "no device");
896 /* mount point */
897 seq_puts(m, " mounted on ");
898 seq_path(m, &mnt_path, " \t\n\\");
899 seq_putc(m, ' ');
901 /* file system type */
902 seq_puts(m, "with fstype ");
903 show_type(m, mnt->mnt_sb);
905 /* optional statistics */
906 if (mnt->mnt_sb->s_op->show_stats) {
907 seq_putc(m, ' ');
908 err = mnt->mnt_sb->s_op->show_stats(m, mnt);
911 seq_putc(m, '\n');
912 return err;
915 const struct seq_operations mountstats_op = {
916 .start = m_start,
917 .next = m_next,
918 .stop = m_stop,
919 .show = show_vfsstat,
921 #endif /* CONFIG_PROC_FS */
924 * may_umount_tree - check if a mount tree is busy
925 * @mnt: root of mount tree
927 * This is called to check if a tree of mounts has any
928 * open files, pwds, chroots or sub mounts that are
929 * busy.
931 int may_umount_tree(struct vfsmount *mnt)
933 int actual_refs = 0;
934 int minimum_refs = 0;
935 struct vfsmount *p;
937 spin_lock(&vfsmount_lock);
938 for (p = mnt; p; p = next_mnt(p, mnt)) {
939 actual_refs += atomic_read(&p->mnt_count);
940 minimum_refs += 2;
942 spin_unlock(&vfsmount_lock);
944 if (actual_refs > minimum_refs)
945 return 0;
947 return 1;
950 EXPORT_SYMBOL(may_umount_tree);
953 * may_umount - check if a mount point is busy
954 * @mnt: root of mount
956 * This is called to check if a mount point has any
957 * open files, pwds, chroots or sub mounts. If the
958 * mount has sub mounts this will return busy
959 * regardless of whether the sub mounts are busy.
961 * Doesn't take quota and stuff into account. IOW, in some cases it will
962 * give false negatives. The main reason why it's here is that we need
963 * a non-destructive way to look for easily umountable filesystems.
965 int may_umount(struct vfsmount *mnt)
967 int ret = 1;
968 spin_lock(&vfsmount_lock);
969 if (propagate_mount_busy(mnt, 2))
970 ret = 0;
971 spin_unlock(&vfsmount_lock);
972 return ret;
975 EXPORT_SYMBOL(may_umount);
977 void release_mounts(struct list_head *head)
979 struct vfsmount *mnt;
980 while (!list_empty(head)) {
981 mnt = list_first_entry(head, struct vfsmount, mnt_hash);
982 list_del_init(&mnt->mnt_hash);
983 if (mnt->mnt_parent != mnt) {
984 struct dentry *dentry;
985 struct vfsmount *m;
986 spin_lock(&vfsmount_lock);
987 dentry = mnt->mnt_mountpoint;
988 m = mnt->mnt_parent;
989 mnt->mnt_mountpoint = mnt->mnt_root;
990 mnt->mnt_parent = mnt;
991 m->mnt_ghosts--;
992 spin_unlock(&vfsmount_lock);
993 dput(dentry);
994 mntput(m);
996 mntput(mnt);
1000 void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
1002 struct vfsmount *p;
1004 for (p = mnt; p; p = next_mnt(p, mnt))
1005 list_move(&p->mnt_hash, kill);
1007 if (propagate)
1008 propagate_umount(kill);
1010 list_for_each_entry(p, kill, mnt_hash) {
1011 list_del_init(&p->mnt_expire);
1012 list_del_init(&p->mnt_list);
1013 __touch_mnt_namespace(p->mnt_ns);
1014 p->mnt_ns = NULL;
1015 list_del_init(&p->mnt_child);
1016 if (p->mnt_parent != p) {
1017 p->mnt_parent->mnt_ghosts++;
1018 p->mnt_mountpoint->d_mounted--;
1020 change_mnt_propagation(p, MS_PRIVATE);
1024 static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts);
1026 static int do_umount(struct vfsmount *mnt, int flags)
1028 struct super_block *sb = mnt->mnt_sb;
1029 int retval;
1030 LIST_HEAD(umount_list);
1032 retval = security_sb_umount(mnt, flags);
1033 if (retval)
1034 return retval;
1037 * Allow userspace to request a mountpoint be expired rather than
1038 * unmounting unconditionally. Unmount only happens if:
1039 * (1) the mark is already set (the mark is cleared by mntput())
1040 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
1042 if (flags & MNT_EXPIRE) {
1043 if (mnt == current->fs->root.mnt ||
1044 flags & (MNT_FORCE | MNT_DETACH))
1045 return -EINVAL;
1047 if (atomic_read(&mnt->mnt_count) != 2)
1048 return -EBUSY;
1050 if (!xchg(&mnt->mnt_expiry_mark, 1))
1051 return -EAGAIN;
1055 * If we may have to abort operations to get out of this
1056 * mount, and they will themselves hold resources we must
1057 * allow the fs to do things. In the Unix tradition of
1058 * 'Gee thats tricky lets do it in userspace' the umount_begin
1059 * might fail to complete on the first run through as other tasks
1060 * must return, and the like. Thats for the mount program to worry
1061 * about for the moment.
1064 if (flags & MNT_FORCE && sb->s_op->umount_begin) {
1065 sb->s_op->umount_begin(sb);
1069 * No sense to grab the lock for this test, but test itself looks
1070 * somewhat bogus. Suggestions for better replacement?
1071 * Ho-hum... In principle, we might treat that as umount + switch
1072 * to rootfs. GC would eventually take care of the old vfsmount.
1073 * Actually it makes sense, especially if rootfs would contain a
1074 * /reboot - static binary that would close all descriptors and
1075 * call reboot(9). Then init(8) could umount root and exec /reboot.
1077 if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
1079 * Special case for "unmounting" root ...
1080 * we just try to remount it readonly.
1082 down_write(&sb->s_umount);
1083 if (!(sb->s_flags & MS_RDONLY))
1084 retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
1085 up_write(&sb->s_umount);
1086 return retval;
1089 down_write(&namespace_sem);
1090 spin_lock(&vfsmount_lock);
1091 event++;
1093 if (!(flags & MNT_DETACH))
1094 shrink_submounts(mnt, &umount_list);
1096 retval = -EBUSY;
1097 if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
1098 if (!list_empty(&mnt->mnt_list))
1099 umount_tree(mnt, 1, &umount_list);
1100 retval = 0;
1102 spin_unlock(&vfsmount_lock);
1103 if (retval)
1104 security_sb_umount_busy(mnt);
1105 up_write(&namespace_sem);
1106 release_mounts(&umount_list);
1107 return retval;
1111 * Now umount can handle mount points as well as block devices.
1112 * This is important for filesystems which use unnamed block devices.
1114 * We now support a flag for forced unmount like the other 'big iron'
1115 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
1118 SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
1120 struct path path;
1121 int retval;
1123 retval = user_path(name, &path);
1124 if (retval)
1125 goto out;
1126 retval = -EINVAL;
1127 if (path.dentry != path.mnt->mnt_root)
1128 goto dput_and_out;
1129 if (!check_mnt(path.mnt))
1130 goto dput_and_out;
1132 retval = -EPERM;
1133 if (!capable(CAP_SYS_ADMIN))
1134 goto dput_and_out;
1136 retval = do_umount(path.mnt, flags);
1137 dput_and_out:
1138 /* we mustn't call path_put() as that would clear mnt_expiry_mark */
1139 dput(path.dentry);
1140 mntput_no_expire(path.mnt);
1141 out:
1142 return retval;
1145 #ifdef __ARCH_WANT_SYS_OLDUMOUNT
1148 * The 2.0 compatible umount. No flags.
1150 SYSCALL_DEFINE1(oldumount, char __user *, name)
1152 return sys_umount(name, 0);
1155 #endif
1157 static int mount_is_safe(struct path *path)
1159 if (capable(CAP_SYS_ADMIN))
1160 return 0;
1161 return -EPERM;
1162 #ifdef notyet
1163 if (S_ISLNK(path->dentry->d_inode->i_mode))
1164 return -EPERM;
1165 if (path->dentry->d_inode->i_mode & S_ISVTX) {
1166 if (current_uid() != path->dentry->d_inode->i_uid)
1167 return -EPERM;
1169 if (inode_permission(path->dentry->d_inode, MAY_WRITE))
1170 return -EPERM;
1171 return 0;
1172 #endif
1175 struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
1176 int flag)
1178 struct vfsmount *res, *p, *q, *r, *s;
1179 struct path path;
1181 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
1182 return NULL;
1184 res = q = clone_mnt(mnt, dentry, flag);
1185 if (!q)
1186 goto Enomem;
1187 q->mnt_mountpoint = mnt->mnt_mountpoint;
1189 p = mnt;
1190 list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
1191 if (!is_subdir(r->mnt_mountpoint, dentry))
1192 continue;
1194 for (s = r; s; s = next_mnt(s, r)) {
1195 if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
1196 s = skip_mnt_tree(s);
1197 continue;
1199 while (p != s->mnt_parent) {
1200 p = p->mnt_parent;
1201 q = q->mnt_parent;
1203 p = s;
1204 path.mnt = q;
1205 path.dentry = p->mnt_mountpoint;
1206 q = clone_mnt(p, p->mnt_root, flag);
1207 if (!q)
1208 goto Enomem;
1209 spin_lock(&vfsmount_lock);
1210 list_add_tail(&q->mnt_list, &res->mnt_list);
1211 attach_mnt(q, &path);
1212 spin_unlock(&vfsmount_lock);
1215 return res;
1216 Enomem:
1217 if (res) {
1218 LIST_HEAD(umount_list);
1219 spin_lock(&vfsmount_lock);
1220 umount_tree(res, 0, &umount_list);
1221 spin_unlock(&vfsmount_lock);
1222 release_mounts(&umount_list);
1224 return NULL;
1227 struct vfsmount *collect_mounts(struct path *path)
1229 struct vfsmount *tree;
1230 down_write(&namespace_sem);
1231 tree = copy_tree(path->mnt, path->dentry, CL_COPY_ALL | CL_PRIVATE);
1232 up_write(&namespace_sem);
1233 return tree;
1236 void drop_collected_mounts(struct vfsmount *mnt)
1238 LIST_HEAD(umount_list);
1239 down_write(&namespace_sem);
1240 spin_lock(&vfsmount_lock);
1241 umount_tree(mnt, 0, &umount_list);
1242 spin_unlock(&vfsmount_lock);
1243 up_write(&namespace_sem);
1244 release_mounts(&umount_list);
1247 static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end)
1249 struct vfsmount *p;
1251 for (p = mnt; p != end; p = next_mnt(p, mnt)) {
1252 if (p->mnt_group_id && !IS_MNT_SHARED(p))
1253 mnt_release_group_id(p);
1257 static int invent_group_ids(struct vfsmount *mnt, bool recurse)
1259 struct vfsmount *p;
1261 for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) {
1262 if (!p->mnt_group_id && !IS_MNT_SHARED(p)) {
1263 int err = mnt_alloc_group_id(p);
1264 if (err) {
1265 cleanup_group_ids(mnt, p);
1266 return err;
1271 return 0;
1275 * @source_mnt : mount tree to be attached
1276 * @nd : place the mount tree @source_mnt is attached
1277 * @parent_nd : if non-null, detach the source_mnt from its parent and
1278 * store the parent mount and mountpoint dentry.
1279 * (done when source_mnt is moved)
1281 * NOTE: in the table below explains the semantics when a source mount
1282 * of a given type is attached to a destination mount of a given type.
1283 * ---------------------------------------------------------------------------
1284 * | BIND MOUNT OPERATION |
1285 * |**************************************************************************
1286 * | source-->| shared | private | slave | unbindable |
1287 * | dest | | | | |
1288 * | | | | | | |
1289 * | v | | | | |
1290 * |**************************************************************************
1291 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
1292 * | | | | | |
1293 * |non-shared| shared (+) | private | slave (*) | invalid |
1294 * ***************************************************************************
1295 * A bind operation clones the source mount and mounts the clone on the
1296 * destination mount.
1298 * (++) the cloned mount is propagated to all the mounts in the propagation
1299 * tree of the destination mount and the cloned mount is added to
1300 * the peer group of the source mount.
1301 * (+) the cloned mount is created under the destination mount and is marked
1302 * as shared. The cloned mount is added to the peer group of the source
1303 * mount.
1304 * (+++) the mount is propagated to all the mounts in the propagation tree
1305 * of the destination mount and the cloned mount is made slave
1306 * of the same master as that of the source mount. The cloned mount
1307 * is marked as 'shared and slave'.
1308 * (*) the cloned mount is made a slave of the same master as that of the
1309 * source mount.
1311 * ---------------------------------------------------------------------------
1312 * | MOVE MOUNT OPERATION |
1313 * |**************************************************************************
1314 * | source-->| shared | private | slave | unbindable |
1315 * | dest | | | | |
1316 * | | | | | | |
1317 * | v | | | | |
1318 * |**************************************************************************
1319 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
1320 * | | | | | |
1321 * |non-shared| shared (+*) | private | slave (*) | unbindable |
1322 * ***************************************************************************
1324 * (+) the mount is moved to the destination. And is then propagated to
1325 * all the mounts in the propagation tree of the destination mount.
1326 * (+*) the mount is moved to the destination.
1327 * (+++) the mount is moved to the destination and is then propagated to
1328 * all the mounts belonging to the destination mount's propagation tree.
1329 * the mount is marked as 'shared and slave'.
1330 * (*) the mount continues to be a slave at the new location.
1332 * if the source mount is a tree, the operations explained above is
1333 * applied to each mount in the tree.
1334 * Must be called without spinlocks held, since this function can sleep
1335 * in allocations.
1337 static int attach_recursive_mnt(struct vfsmount *source_mnt,
1338 struct path *path, struct path *parent_path)
1340 LIST_HEAD(tree_list);
1341 struct vfsmount *dest_mnt = path->mnt;
1342 struct dentry *dest_dentry = path->dentry;
1343 struct vfsmount *child, *p;
1344 int err;
1346 if (IS_MNT_SHARED(dest_mnt)) {
1347 err = invent_group_ids(source_mnt, true);
1348 if (err)
1349 goto out;
1351 err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list);
1352 if (err)
1353 goto out_cleanup_ids;
1355 if (IS_MNT_SHARED(dest_mnt)) {
1356 for (p = source_mnt; p; p = next_mnt(p, source_mnt))
1357 set_mnt_shared(p);
1360 spin_lock(&vfsmount_lock);
1361 if (parent_path) {
1362 detach_mnt(source_mnt, parent_path);
1363 attach_mnt(source_mnt, path);
1364 touch_mnt_namespace(parent_path->mnt->mnt_ns);
1365 } else {
1366 mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
1367 commit_tree(source_mnt);
1370 list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
1371 list_del_init(&child->mnt_hash);
1372 commit_tree(child);
1374 spin_unlock(&vfsmount_lock);
1375 return 0;
1377 out_cleanup_ids:
1378 if (IS_MNT_SHARED(dest_mnt))
1379 cleanup_group_ids(source_mnt, NULL);
1380 out:
1381 return err;
1384 static int graft_tree(struct vfsmount *mnt, struct path *path)
1386 int err;
1387 if (mnt->mnt_sb->s_flags & MS_NOUSER)
1388 return -EINVAL;
1390 if (S_ISDIR(path->dentry->d_inode->i_mode) !=
1391 S_ISDIR(mnt->mnt_root->d_inode->i_mode))
1392 return -ENOTDIR;
1394 err = -ENOENT;
1395 mutex_lock(&path->dentry->d_inode->i_mutex);
1396 if (IS_DEADDIR(path->dentry->d_inode))
1397 goto out_unlock;
1399 err = security_sb_check_sb(mnt, path);
1400 if (err)
1401 goto out_unlock;
1403 err = -ENOENT;
1404 if (!d_unlinked(path->dentry))
1405 err = attach_recursive_mnt(mnt, path, NULL);
1406 out_unlock:
1407 mutex_unlock(&path->dentry->d_inode->i_mutex);
1408 if (!err)
1409 security_sb_post_addmount(mnt, path);
1410 return err;
1414 * recursively change the type of the mountpoint.
1416 static int do_change_type(struct path *path, int flag)
1418 struct vfsmount *m, *mnt = path->mnt;
1419 int recurse = flag & MS_REC;
1420 int type = flag & ~MS_REC;
1421 int err = 0;
1423 if (!capable(CAP_SYS_ADMIN))
1424 return -EPERM;
1426 if (path->dentry != path->mnt->mnt_root)
1427 return -EINVAL;
1429 down_write(&namespace_sem);
1430 if (type == MS_SHARED) {
1431 err = invent_group_ids(mnt, recurse);
1432 if (err)
1433 goto out_unlock;
1436 spin_lock(&vfsmount_lock);
1437 for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
1438 change_mnt_propagation(m, type);
1439 spin_unlock(&vfsmount_lock);
1441 out_unlock:
1442 up_write(&namespace_sem);
1443 return err;
1447 * do loopback mount.
1449 static int do_loopback(struct path *path, char *old_name,
1450 int recurse)
1452 struct path old_path;
1453 struct vfsmount *mnt = NULL;
1454 int err = mount_is_safe(path);
1455 if (err)
1456 return err;
1457 if (!old_name || !*old_name)
1458 return -EINVAL;
1459 err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
1460 if (err)
1461 return err;
1463 down_write(&namespace_sem);
1464 err = -EINVAL;
1465 if (IS_MNT_UNBINDABLE(old_path.mnt))
1466 goto out;
1468 if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
1469 goto out;
1471 err = -ENOMEM;
1472 if (recurse)
1473 mnt = copy_tree(old_path.mnt, old_path.dentry, 0);
1474 else
1475 mnt = clone_mnt(old_path.mnt, old_path.dentry, 0);
1477 if (!mnt)
1478 goto out;
1480 err = graft_tree(mnt, path);
1481 if (err) {
1482 LIST_HEAD(umount_list);
1483 spin_lock(&vfsmount_lock);
1484 umount_tree(mnt, 0, &umount_list);
1485 spin_unlock(&vfsmount_lock);
1486 release_mounts(&umount_list);
1489 out:
1490 up_write(&namespace_sem);
1491 path_put(&old_path);
1492 return err;
1495 static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
1497 int error = 0;
1498 int readonly_request = 0;
1500 if (ms_flags & MS_RDONLY)
1501 readonly_request = 1;
1502 if (readonly_request == __mnt_is_readonly(mnt))
1503 return 0;
1505 if (readonly_request)
1506 error = mnt_make_readonly(mnt);
1507 else
1508 __mnt_unmake_readonly(mnt);
1509 return error;
1513 * change filesystem flags. dir should be a physical root of filesystem.
1514 * If you've mounted a non-root directory somewhere and want to do remount
1515 * on it - tough luck.
1517 static int do_remount(struct path *path, int flags, int mnt_flags,
1518 void *data)
1520 int err;
1521 struct super_block *sb = path->mnt->mnt_sb;
1523 if (!capable(CAP_SYS_ADMIN))
1524 return -EPERM;
1526 if (!check_mnt(path->mnt))
1527 return -EINVAL;
1529 if (path->dentry != path->mnt->mnt_root)
1530 return -EINVAL;
1532 down_write(&sb->s_umount);
1533 if (flags & MS_BIND)
1534 err = change_mount_flags(path->mnt, flags);
1535 else
1536 err = do_remount_sb(sb, flags, data, 0);
1537 if (!err)
1538 path->mnt->mnt_flags = mnt_flags;
1539 up_write(&sb->s_umount);
1540 if (!err) {
1541 security_sb_post_remount(path->mnt, flags, data);
1543 spin_lock(&vfsmount_lock);
1544 touch_mnt_namespace(path->mnt->mnt_ns);
1545 spin_unlock(&vfsmount_lock);
1547 return err;
1550 static inline int tree_contains_unbindable(struct vfsmount *mnt)
1552 struct vfsmount *p;
1553 for (p = mnt; p; p = next_mnt(p, mnt)) {
1554 if (IS_MNT_UNBINDABLE(p))
1555 return 1;
1557 return 0;
1560 static int do_move_mount(struct path *path, char *old_name)
1562 struct path old_path, parent_path;
1563 struct vfsmount *p;
1564 int err = 0;
1565 if (!capable(CAP_SYS_ADMIN))
1566 return -EPERM;
1567 if (!old_name || !*old_name)
1568 return -EINVAL;
1569 err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
1570 if (err)
1571 return err;
1573 down_write(&namespace_sem);
1574 while (d_mountpoint(path->dentry) &&
1575 follow_down(path))
1577 err = -EINVAL;
1578 if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
1579 goto out;
1581 err = -ENOENT;
1582 mutex_lock(&path->dentry->d_inode->i_mutex);
1583 if (IS_DEADDIR(path->dentry->d_inode))
1584 goto out1;
1586 if (d_unlinked(path->dentry))
1587 goto out1;
1589 err = -EINVAL;
1590 if (old_path.dentry != old_path.mnt->mnt_root)
1591 goto out1;
1593 if (old_path.mnt == old_path.mnt->mnt_parent)
1594 goto out1;
1596 if (S_ISDIR(path->dentry->d_inode->i_mode) !=
1597 S_ISDIR(old_path.dentry->d_inode->i_mode))
1598 goto out1;
1600 * Don't move a mount residing in a shared parent.
1602 if (old_path.mnt->mnt_parent &&
1603 IS_MNT_SHARED(old_path.mnt->mnt_parent))
1604 goto out1;
1606 * Don't move a mount tree containing unbindable mounts to a destination
1607 * mount which is shared.
1609 if (IS_MNT_SHARED(path->mnt) &&
1610 tree_contains_unbindable(old_path.mnt))
1611 goto out1;
1612 err = -ELOOP;
1613 for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent)
1614 if (p == old_path.mnt)
1615 goto out1;
1617 err = attach_recursive_mnt(old_path.mnt, path, &parent_path);
1618 if (err)
1619 goto out1;
1621 /* if the mount is moved, it should no longer be expire
1622 * automatically */
1623 list_del_init(&old_path.mnt->mnt_expire);
1624 out1:
1625 mutex_unlock(&path->dentry->d_inode->i_mutex);
1626 out:
1627 up_write(&namespace_sem);
1628 if (!err)
1629 path_put(&parent_path);
1630 path_put(&old_path);
1631 return err;
1635 * create a new mount for userspace and request it to be added into the
1636 * namespace's tree
1638 static int do_new_mount(struct path *path, char *type, int flags,
1639 int mnt_flags, char *name, void *data)
1641 struct vfsmount *mnt;
1643 if (!type)
1644 return -EINVAL;
1646 /* we need capabilities... */
1647 if (!capable(CAP_SYS_ADMIN))
1648 return -EPERM;
1650 lock_kernel();
1651 mnt = do_kern_mount(type, flags, name, data);
1652 unlock_kernel();
1653 if (IS_ERR(mnt))
1654 return PTR_ERR(mnt);
1656 return do_add_mount(mnt, path, mnt_flags, NULL);
1660 * add a mount into a namespace's mount tree
1661 * - provide the option of adding the new mount to an expiration list
1663 int do_add_mount(struct vfsmount *newmnt, struct path *path,
1664 int mnt_flags, struct list_head *fslist)
1666 int err;
1668 down_write(&namespace_sem);
1669 /* Something was mounted here while we slept */
1670 while (d_mountpoint(path->dentry) &&
1671 follow_down(path))
1673 err = -EINVAL;
1674 if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt))
1675 goto unlock;
1677 /* Refuse the same filesystem on the same mount point */
1678 err = -EBUSY;
1679 if (path->mnt->mnt_sb == newmnt->mnt_sb &&
1680 path->mnt->mnt_root == path->dentry)
1681 goto unlock;
1683 err = -EINVAL;
1684 if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
1685 goto unlock;
1687 newmnt->mnt_flags = mnt_flags;
1688 if ((err = graft_tree(newmnt, path)))
1689 goto unlock;
1691 if (fslist) /* add to the specified expiration list */
1692 list_add_tail(&newmnt->mnt_expire, fslist);
1694 up_write(&namespace_sem);
1695 return 0;
1697 unlock:
1698 up_write(&namespace_sem);
1699 mntput(newmnt);
1700 return err;
1703 EXPORT_SYMBOL_GPL(do_add_mount);
1706 * process a list of expirable mountpoints with the intent of discarding any
1707 * mountpoints that aren't in use and haven't been touched since last we came
1708 * here
1710 void mark_mounts_for_expiry(struct list_head *mounts)
1712 struct vfsmount *mnt, *next;
1713 LIST_HEAD(graveyard);
1714 LIST_HEAD(umounts);
1716 if (list_empty(mounts))
1717 return;
1719 down_write(&namespace_sem);
1720 spin_lock(&vfsmount_lock);
1722 /* extract from the expiration list every vfsmount that matches the
1723 * following criteria:
1724 * - only referenced by its parent vfsmount
1725 * - still marked for expiry (marked on the last call here; marks are
1726 * cleared by mntput())
1728 list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
1729 if (!xchg(&mnt->mnt_expiry_mark, 1) ||
1730 propagate_mount_busy(mnt, 1))
1731 continue;
1732 list_move(&mnt->mnt_expire, &graveyard);
1734 while (!list_empty(&graveyard)) {
1735 mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire);
1736 touch_mnt_namespace(mnt->mnt_ns);
1737 umount_tree(mnt, 1, &umounts);
1739 spin_unlock(&vfsmount_lock);
1740 up_write(&namespace_sem);
1742 release_mounts(&umounts);
1745 EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
1748 * Ripoff of 'select_parent()'
1750 * search the list of submounts for a given mountpoint, and move any
1751 * shrinkable submounts to the 'graveyard' list.
1753 static int select_submounts(struct vfsmount *parent, struct list_head *graveyard)
1755 struct vfsmount *this_parent = parent;
1756 struct list_head *next;
1757 int found = 0;
1759 repeat:
1760 next = this_parent->mnt_mounts.next;
1761 resume:
1762 while (next != &this_parent->mnt_mounts) {
1763 struct list_head *tmp = next;
1764 struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child);
1766 next = tmp->next;
1767 if (!(mnt->mnt_flags & MNT_SHRINKABLE))
1768 continue;
1770 * Descend a level if the d_mounts list is non-empty.
1772 if (!list_empty(&mnt->mnt_mounts)) {
1773 this_parent = mnt;
1774 goto repeat;
1777 if (!propagate_mount_busy(mnt, 1)) {
1778 list_move_tail(&mnt->mnt_expire, graveyard);
1779 found++;
1783 * All done at this level ... ascend and resume the search
1785 if (this_parent != parent) {
1786 next = this_parent->mnt_child.next;
1787 this_parent = this_parent->mnt_parent;
1788 goto resume;
1790 return found;
1794 * process a list of expirable mountpoints with the intent of discarding any
1795 * submounts of a specific parent mountpoint
1797 static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts)
1799 LIST_HEAD(graveyard);
1800 struct vfsmount *m;
1802 /* extract submounts of 'mountpoint' from the expiration list */
1803 while (select_submounts(mnt, &graveyard)) {
1804 while (!list_empty(&graveyard)) {
1805 m = list_first_entry(&graveyard, struct vfsmount,
1806 mnt_expire);
1807 touch_mnt_namespace(m->mnt_ns);
1808 umount_tree(m, 1, umounts);
1814 * Some copy_from_user() implementations do not return the exact number of
1815 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
1816 * Note that this function differs from copy_from_user() in that it will oops
1817 * on bad values of `to', rather than returning a short copy.
1819 static long exact_copy_from_user(void *to, const void __user * from,
1820 unsigned long n)
1822 char *t = to;
1823 const char __user *f = from;
1824 char c;
1826 if (!access_ok(VERIFY_READ, from, n))
1827 return n;
1829 while (n) {
1830 if (__get_user(c, f)) {
1831 memset(t, 0, n);
1832 break;
1834 *t++ = c;
1835 f++;
1836 n--;
1838 return n;
1841 int copy_mount_options(const void __user * data, unsigned long *where)
1843 int i;
1844 unsigned long page;
1845 unsigned long size;
1847 *where = 0;
1848 if (!data)
1849 return 0;
1851 if (!(page = __get_free_page(GFP_KERNEL)))
1852 return -ENOMEM;
1854 /* We only care that *some* data at the address the user
1855 * gave us is valid. Just in case, we'll zero
1856 * the remainder of the page.
1858 /* copy_from_user cannot cross TASK_SIZE ! */
1859 size = TASK_SIZE - (unsigned long)data;
1860 if (size > PAGE_SIZE)
1861 size = PAGE_SIZE;
1863 i = size - exact_copy_from_user((void *)page, data, size);
1864 if (!i) {
1865 free_page(page);
1866 return -EFAULT;
1868 if (i != PAGE_SIZE)
1869 memset((char *)page + i, 0, PAGE_SIZE - i);
1870 *where = page;
1871 return 0;
1874 int copy_mount_string(const void __user *data, char **where)
1876 char *tmp;
1878 if (!data) {
1879 *where = NULL;
1880 return 0;
1883 tmp = strndup_user(data, PAGE_SIZE);
1884 if (IS_ERR(tmp))
1885 return PTR_ERR(tmp);
1887 *where = tmp;
1888 return 0;
1892 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
1893 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
1895 * data is a (void *) that can point to any structure up to
1896 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
1897 * information (or be NULL).
1899 * Pre-0.97 versions of mount() didn't have a flags word.
1900 * When the flags word was introduced its top half was required
1901 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
1902 * Therefore, if this magic number is present, it carries no information
1903 * and must be discarded.
1905 long do_mount(char *dev_name, char *dir_name, char *type_page,
1906 unsigned long flags, void *data_page)
1908 struct path path;
1909 int retval = 0;
1910 int mnt_flags = 0;
1912 /* Discard magic */
1913 if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
1914 flags &= ~MS_MGC_MSK;
1916 /* Basic sanity checks */
1918 if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
1919 return -EINVAL;
1921 if (data_page)
1922 ((char *)data_page)[PAGE_SIZE - 1] = 0;
1924 /* Default to relatime unless overriden */
1925 if (!(flags & MS_NOATIME))
1926 mnt_flags |= MNT_RELATIME;
1928 /* Separate the per-mountpoint flags */
1929 if (flags & MS_NOSUID)
1930 mnt_flags |= MNT_NOSUID;
1931 if (flags & MS_NODEV)
1932 mnt_flags |= MNT_NODEV;
1933 if (flags & MS_NOEXEC)
1934 mnt_flags |= MNT_NOEXEC;
1935 if (flags & MS_NOATIME)
1936 mnt_flags |= MNT_NOATIME;
1937 if (flags & MS_NODIRATIME)
1938 mnt_flags |= MNT_NODIRATIME;
1939 if (flags & MS_STRICTATIME)
1940 mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
1941 if (flags & MS_RDONLY)
1942 mnt_flags |= MNT_READONLY;
1944 flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
1945 MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
1946 MS_STRICTATIME);
1948 /* ... and get the mountpoint */
1949 retval = kern_path(dir_name, LOOKUP_FOLLOW, &path);
1950 if (retval)
1951 return retval;
1953 retval = security_sb_mount(dev_name, &path,
1954 type_page, flags, data_page);
1955 if (retval)
1956 goto dput_out;
1958 if (flags & MS_REMOUNT)
1959 retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags,
1960 data_page);
1961 else if (flags & MS_BIND)
1962 retval = do_loopback(&path, dev_name, flags & MS_REC);
1963 else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
1964 retval = do_change_type(&path, flags);
1965 else if (flags & MS_MOVE)
1966 retval = do_move_mount(&path, dev_name);
1967 else
1968 retval = do_new_mount(&path, type_page, flags, mnt_flags,
1969 dev_name, data_page);
1970 dput_out:
1971 path_put(&path);
1972 return retval;
1975 static struct mnt_namespace *alloc_mnt_ns(void)
1977 struct mnt_namespace *new_ns;
1979 new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
1980 if (!new_ns)
1981 return ERR_PTR(-ENOMEM);
1982 atomic_set(&new_ns->count, 1);
1983 new_ns->root = NULL;
1984 INIT_LIST_HEAD(&new_ns->list);
1985 init_waitqueue_head(&new_ns->poll);
1986 new_ns->event = 0;
1987 return new_ns;
1991 * Allocate a new namespace structure and populate it with contents
1992 * copied from the namespace of the passed in task structure.
1994 static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
1995 struct fs_struct *fs)
1997 struct mnt_namespace *new_ns;
1998 struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
1999 struct vfsmount *p, *q;
2001 new_ns = alloc_mnt_ns();
2002 if (IS_ERR(new_ns))
2003 return new_ns;
2005 down_write(&namespace_sem);
2006 /* First pass: copy the tree topology */
2007 new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root,
2008 CL_COPY_ALL | CL_EXPIRE);
2009 if (!new_ns->root) {
2010 up_write(&namespace_sem);
2011 kfree(new_ns);
2012 return ERR_PTR(-ENOMEM);
2014 spin_lock(&vfsmount_lock);
2015 list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
2016 spin_unlock(&vfsmount_lock);
2019 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
2020 * as belonging to new namespace. We have already acquired a private
2021 * fs_struct, so tsk->fs->lock is not needed.
2023 p = mnt_ns->root;
2024 q = new_ns->root;
2025 while (p) {
2026 q->mnt_ns = new_ns;
2027 if (fs) {
2028 if (p == fs->root.mnt) {
2029 rootmnt = p;
2030 fs->root.mnt = mntget(q);
2032 if (p == fs->pwd.mnt) {
2033 pwdmnt = p;
2034 fs->pwd.mnt = mntget(q);
2037 p = next_mnt(p, mnt_ns->root);
2038 q = next_mnt(q, new_ns->root);
2040 up_write(&namespace_sem);
2042 if (rootmnt)
2043 mntput(rootmnt);
2044 if (pwdmnt)
2045 mntput(pwdmnt);
2047 return new_ns;
2050 struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
2051 struct fs_struct *new_fs)
2053 struct mnt_namespace *new_ns;
2055 BUG_ON(!ns);
2056 get_mnt_ns(ns);
2058 if (!(flags & CLONE_NEWNS))
2059 return ns;
2061 new_ns = dup_mnt_ns(ns, new_fs);
2063 put_mnt_ns(ns);
2064 return new_ns;
2068 * create_mnt_ns - creates a private namespace and adds a root filesystem
2069 * @mnt: pointer to the new root filesystem mountpoint
2071 struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt)
2073 struct mnt_namespace *new_ns;
2075 new_ns = alloc_mnt_ns();
2076 if (!IS_ERR(new_ns)) {
2077 mnt->mnt_ns = new_ns;
2078 new_ns->root = mnt;
2079 list_add(&new_ns->list, &new_ns->root->mnt_list);
2081 return new_ns;
2083 EXPORT_SYMBOL(create_mnt_ns);
2085 SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
2086 char __user *, type, unsigned long, flags, void __user *, data)
2088 int ret;
2089 char *kernel_type;
2090 char *kernel_dir;
2091 char *kernel_dev;
2092 unsigned long data_page;
2094 ret = copy_mount_string(type, &kernel_type);
2095 if (ret < 0)
2096 goto out_type;
2098 kernel_dir = getname(dir_name);
2099 if (IS_ERR(kernel_dir)) {
2100 ret = PTR_ERR(kernel_dir);
2101 goto out_dir;
2104 ret = copy_mount_string(dev_name, &kernel_dev);
2105 if (ret < 0)
2106 goto out_dev;
2108 ret = copy_mount_options(data, &data_page);
2109 if (ret < 0)
2110 goto out_data;
2112 ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags,
2113 (void *) data_page);
2115 free_page(data_page);
2116 out_data:
2117 kfree(kernel_dev);
2118 out_dev:
2119 putname(kernel_dir);
2120 out_dir:
2121 kfree(kernel_type);
2122 out_type:
2123 return ret;
2127 * pivot_root Semantics:
2128 * Moves the root file system of the current process to the directory put_old,
2129 * makes new_root as the new root file system of the current process, and sets
2130 * root/cwd of all processes which had them on the current root to new_root.
2132 * Restrictions:
2133 * The new_root and put_old must be directories, and must not be on the
2134 * same file system as the current process root. The put_old must be
2135 * underneath new_root, i.e. adding a non-zero number of /.. to the string
2136 * pointed to by put_old must yield the same directory as new_root. No other
2137 * file system may be mounted on put_old. After all, new_root is a mountpoint.
2139 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
2140 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
2141 * in this situation.
2143 * Notes:
2144 * - we don't move root/cwd if they are not at the root (reason: if something
2145 * cared enough to change them, it's probably wrong to force them elsewhere)
2146 * - it's okay to pick a root that isn't the root of a file system, e.g.
2147 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
2148 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
2149 * first.
2151 SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
2152 const char __user *, put_old)
2154 struct vfsmount *tmp;
2155 struct path new, old, parent_path, root_parent, root;
2156 int error;
2158 if (!capable(CAP_SYS_ADMIN))
2159 return -EPERM;
2161 error = user_path_dir(new_root, &new);
2162 if (error)
2163 goto out0;
2164 error = -EINVAL;
2165 if (!check_mnt(new.mnt))
2166 goto out1;
2168 error = user_path_dir(put_old, &old);
2169 if (error)
2170 goto out1;
2172 error = security_sb_pivotroot(&old, &new);
2173 if (error) {
2174 path_put(&old);
2175 goto out1;
2178 read_lock(&current->fs->lock);
2179 root = current->fs->root;
2180 path_get(&current->fs->root);
2181 read_unlock(&current->fs->lock);
2182 down_write(&namespace_sem);
2183 mutex_lock(&old.dentry->d_inode->i_mutex);
2184 error = -EINVAL;
2185 if (IS_MNT_SHARED(old.mnt) ||
2186 IS_MNT_SHARED(new.mnt->mnt_parent) ||
2187 IS_MNT_SHARED(root.mnt->mnt_parent))
2188 goto out2;
2189 if (!check_mnt(root.mnt))
2190 goto out2;
2191 error = -ENOENT;
2192 if (IS_DEADDIR(new.dentry->d_inode))
2193 goto out2;
2194 if (d_unlinked(new.dentry))
2195 goto out2;
2196 if (d_unlinked(old.dentry))
2197 goto out2;
2198 error = -EBUSY;
2199 if (new.mnt == root.mnt ||
2200 old.mnt == root.mnt)
2201 goto out2; /* loop, on the same file system */
2202 error = -EINVAL;
2203 if (root.mnt->mnt_root != root.dentry)
2204 goto out2; /* not a mountpoint */
2205 if (root.mnt->mnt_parent == root.mnt)
2206 goto out2; /* not attached */
2207 if (new.mnt->mnt_root != new.dentry)
2208 goto out2; /* not a mountpoint */
2209 if (new.mnt->mnt_parent == new.mnt)
2210 goto out2; /* not attached */
2211 /* make sure we can reach put_old from new_root */
2212 tmp = old.mnt;
2213 spin_lock(&vfsmount_lock);
2214 if (tmp != new.mnt) {
2215 for (;;) {
2216 if (tmp->mnt_parent == tmp)
2217 goto out3; /* already mounted on put_old */
2218 if (tmp->mnt_parent == new.mnt)
2219 break;
2220 tmp = tmp->mnt_parent;
2222 if (!is_subdir(tmp->mnt_mountpoint, new.dentry))
2223 goto out3;
2224 } else if (!is_subdir(old.dentry, new.dentry))
2225 goto out3;
2226 detach_mnt(new.mnt, &parent_path);
2227 detach_mnt(root.mnt, &root_parent);
2228 /* mount old root on put_old */
2229 attach_mnt(root.mnt, &old);
2230 /* mount new_root on / */
2231 attach_mnt(new.mnt, &root_parent);
2232 touch_mnt_namespace(current->nsproxy->mnt_ns);
2233 spin_unlock(&vfsmount_lock);
2234 chroot_fs_refs(&root, &new);
2235 security_sb_post_pivotroot(&root, &new);
2236 error = 0;
2237 path_put(&root_parent);
2238 path_put(&parent_path);
2239 out2:
2240 mutex_unlock(&old.dentry->d_inode->i_mutex);
2241 up_write(&namespace_sem);
2242 path_put(&root);
2243 path_put(&old);
2244 out1:
2245 path_put(&new);
2246 out0:
2247 return error;
2248 out3:
2249 spin_unlock(&vfsmount_lock);
2250 goto out2;
2253 static void __init init_mount_tree(void)
2255 struct vfsmount *mnt;
2256 struct mnt_namespace *ns;
2257 struct path root;
2259 mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
2260 if (IS_ERR(mnt))
2261 panic("Can't create rootfs");
2262 ns = create_mnt_ns(mnt);
2263 if (IS_ERR(ns))
2264 panic("Can't allocate initial namespace");
2266 init_task.nsproxy->mnt_ns = ns;
2267 get_mnt_ns(ns);
2269 root.mnt = ns->root;
2270 root.dentry = ns->root->mnt_root;
2272 set_fs_pwd(current->fs, &root);
2273 set_fs_root(current->fs, &root);
2276 void __init mnt_init(void)
2278 unsigned u;
2279 int err;
2281 init_rwsem(&namespace_sem);
2283 mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
2284 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
2286 mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
2288 if (!mount_hashtable)
2289 panic("Failed to allocate mount hash table\n");
2291 printk("Mount-cache hash table entries: %lu\n", HASH_SIZE);
2293 for (u = 0; u < HASH_SIZE; u++)
2294 INIT_LIST_HEAD(&mount_hashtable[u]);
2296 err = sysfs_init();
2297 if (err)
2298 printk(KERN_WARNING "%s: sysfs_init error: %d\n",
2299 __func__, err);
2300 fs_kobj = kobject_create_and_add("fs", NULL);
2301 if (!fs_kobj)
2302 printk(KERN_WARNING "%s: kobj create error\n", __func__);
2303 init_rootfs();
2304 init_mount_tree();
2307 void put_mnt_ns(struct mnt_namespace *ns)
2309 struct vfsmount *root;
2310 LIST_HEAD(umount_list);
2312 if (!atomic_dec_and_lock(&ns->count, &vfsmount_lock))
2313 return;
2314 root = ns->root;
2315 ns->root = NULL;
2316 spin_unlock(&vfsmount_lock);
2317 down_write(&namespace_sem);
2318 spin_lock(&vfsmount_lock);
2319 umount_tree(root, 0, &umount_list);
2320 spin_unlock(&vfsmount_lock);
2321 up_write(&namespace_sem);
2322 release_mounts(&umount_list);
2323 kfree(ns);
2325 EXPORT_SYMBOL(put_mnt_ns);