From 934b25c597c0e98304a7eaec198a87e4633a42bb Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 23 Apr 2008 00:04:04 -0400 Subject: [PATCH 1/8] [PATCH] remove unused label in xattr.c (noise from ro-bind) Signed-off-by: Al Viro --- fs/xattr.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/xattr.c b/fs/xattr.c index f7062da505d4..89a942f07e1b 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -307,7 +307,6 @@ sys_fsetxattr(int fd, char __user *name, void __user *value, error = setxattr(dentry, name, value, size, flags); mnt_drop_write(f->f_path.mnt); } -out_fput: fput(f); return error; } From 6092d048183b76bfa3f84b32f8158dd8d10bd811 Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Thu, 27 Mar 2008 13:06:20 +0100 Subject: [PATCH 2/8] [patch 1/7] vfs: mountinfo: add dentry_path() [mszeredi@suse.cz] split big patch into managable chunks Add the following functions: dentry_path() seq_dentry() These are similar to d_path() and seq_path(). But instead of calculating the path within a mount namespace, they calculate the path from the root of the filesystem to a given dentry, ignoring mounts completely. Signed-off-by: Ram Pai Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 88 +++++++++++++++++++++++++++++----------- fs/seq_file.c | 65 +++++++++++++++++++++-------- include/linux/dcache.h | 1 + include/linux/seq_file.h | 2 + 4 files changed, 117 insertions(+), 39 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 43455776711e..635c2aa427ed 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1746,6 +1746,17 @@ shouldnt_be_hashed: goto shouldnt_be_hashed; } +static int prepend(char **buffer, int *buflen, const char *str, + int namelen) +{ + *buflen -= namelen; + if (*buflen < 0) + return -ENAMETOOLONG; + *buffer -= namelen; + memcpy(*buffer, str, namelen); + return 0; +} + /** * d_path - return the path of a dentry * @dentry: dentry to report @@ -1767,17 +1778,11 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt, { char * end = buffer+buflen; char * retval; - int namelen; - *--end = '\0'; - buflen--; - if (!IS_ROOT(dentry) && d_unhashed(dentry)) { - buflen -= 10; - end -= 10; - if (buflen < 0) + prepend(&end, &buflen, "\0", 1); + if (!IS_ROOT(dentry) && d_unhashed(dentry) && + (prepend(&end, &buflen, " (deleted)", 10) != 0)) goto Elong; - memcpy(end, " (deleted)", 10); - } if (buflen < 1) goto Elong; @@ -1804,13 +1809,10 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt, } parent = dentry->d_parent; prefetch(parent); - namelen = dentry->d_name.len; - buflen -= namelen + 1; - if (buflen < 0) + if ((prepend(&end, &buflen, dentry->d_name.name, + dentry->d_name.len) != 0) || + (prepend(&end, &buflen, "/", 1) != 0)) goto Elong; - end -= namelen; - memcpy(end, dentry->d_name.name, namelen); - *--end = '/'; retval = end; dentry = parent; } @@ -1818,12 +1820,10 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt, return retval; global_root: - namelen = dentry->d_name.len; - buflen -= namelen; - if (buflen < 0) + retval += 1; /* hit the slash */ + if (prepend(&retval, &buflen, dentry->d_name.name, + dentry->d_name.len) != 0) goto Elong; - retval -= namelen-1; /* hit the slash */ - memcpy(retval, dentry->d_name.name, namelen); return retval; Elong: return ERR_PTR(-ENAMETOOLONG); @@ -1859,7 +1859,7 @@ char *d_path(struct path *path, char *buf, int buflen) read_lock(¤t->fs->lock); root = current->fs->root; - path_get(¤t->fs->root); + path_get(&root); read_unlock(¤t->fs->lock); spin_lock(&dcache_lock); res = __d_path(path->dentry, path->mnt, &root, buf, buflen); @@ -1889,6 +1889,48 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, return memcpy(buffer, temp, sz); } +/* + * Write full pathname from the root of the filesystem into the buffer. + */ +char *dentry_path(struct dentry *dentry, char *buf, int buflen) +{ + char *end = buf + buflen; + char *retval; + + spin_lock(&dcache_lock); + prepend(&end, &buflen, "\0", 1); + if (!IS_ROOT(dentry) && d_unhashed(dentry) && + (prepend(&end, &buflen, "//deleted", 9) != 0)) + goto Elong; + if (buflen < 1) + goto Elong; + /* Get '/' right */ + retval = end-1; + *retval = '/'; + + for (;;) { + struct dentry *parent; + if (IS_ROOT(dentry)) + break; + + parent = dentry->d_parent; + prefetch(parent); + + if ((prepend(&end, &buflen, dentry->d_name.name, + dentry->d_name.len) != 0) || + (prepend(&end, &buflen, "/", 1) != 0)) + goto Elong; + + retval = end; + dentry = parent; + } + spin_unlock(&dcache_lock); + return retval; +Elong: + spin_unlock(&dcache_lock); + return ERR_PTR(-ENAMETOOLONG); +} + /* * NOTE! The user-level library version returns a * character pointer. The kernel system call just @@ -1918,9 +1960,9 @@ asmlinkage long sys_getcwd(char __user *buf, unsigned long size) read_lock(¤t->fs->lock); pwd = current->fs->pwd; - path_get(¤t->fs->pwd); + path_get(&pwd); root = current->fs->root; - path_get(¤t->fs->root); + path_get(&root); read_unlock(¤t->fs->lock); error = -ENOENT; diff --git a/fs/seq_file.c b/fs/seq_file.c index cdfd996ca6ef..ae59f5a6c5c1 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -350,28 +350,40 @@ int seq_printf(struct seq_file *m, const char *f, ...) } EXPORT_SYMBOL(seq_printf); +static char *mangle_path(char *s, char *p, char *esc) +{ + while (s <= p) { + char c = *p++; + if (!c) { + return s; + } else if (!strchr(esc, c)) { + *s++ = c; + } else if (s + 4 > p) { + break; + } else { + *s++ = '\\'; + *s++ = '0' + ((c & 0300) >> 6); + *s++ = '0' + ((c & 070) >> 3); + *s++ = '0' + (c & 07); + } + } + return NULL; +} + +/* + * return the absolute path of 'dentry' residing in mount 'mnt'. + */ int seq_path(struct seq_file *m, struct path *path, char *esc) { if (m->count < m->size) { char *s = m->buf + m->count; char *p = d_path(path, s, m->size - m->count); if (!IS_ERR(p)) { - while (s <= p) { - char c = *p++; - if (!c) { - p = m->buf + m->count; - m->count = s - m->buf; - return s - p; - } else if (!strchr(esc, c)) { - *s++ = c; - } else if (s + 4 > p) { - break; - } else { - *s++ = '\\'; - *s++ = '0' + ((c & 0300) >> 6); - *s++ = '0' + ((c & 070) >> 3); - *s++ = '0' + (c & 07); - } + s = mangle_path(s, p, esc); + if (s) { + p = m->buf + m->count; + m->count = s - m->buf; + return s - p; } } } @@ -380,6 +392,27 @@ int seq_path(struct seq_file *m, struct path *path, char *esc) } EXPORT_SYMBOL(seq_path); +/* + * returns the path of the 'dentry' from the root of its filesystem. + */ +int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc) +{ + if (m->count < m->size) { + char *s = m->buf + m->count; + char *p = dentry_path(dentry, s, m->size - m->count); + if (!IS_ERR(p)) { + s = mangle_path(s, p, esc); + if (s) { + p = m->buf + m->count; + m->count = s - m->buf; + return s - p; + } + } + } + m->count = m->size; + return -1; +} + static void *single_start(struct seq_file *p, loff_t *pos) { return NULL + (*pos == 0); diff --git a/include/linux/dcache.h b/include/linux/dcache.h index fabd16d03a27..63960033b6f5 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -302,6 +302,7 @@ extern int d_validate(struct dentry *, struct dentry *); extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); extern char *d_path(struct path *, char *, int); +extern char *dentry_path(struct dentry *, char *, int); /* Allocation counts.. */ diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index d65796dc26d9..11676ccef7b3 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -10,6 +10,7 @@ struct seq_operations; struct file; struct path; struct inode; +struct dentry; struct seq_file { char *buf; @@ -44,6 +45,7 @@ int seq_printf(struct seq_file *, const char *, ...) __attribute__ ((format (printf,2,3))); int seq_path(struct seq_file *, struct path *, char *); +int seq_dentry(struct seq_file *, struct dentry *, char *); int single_open(struct file *, int (*)(struct seq_file *, void *), void *); int single_release(struct inode *, struct file *); From 9d1bc60138977d9c79471b344a64f2df13b2ccef Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 27 Mar 2008 13:06:21 +0100 Subject: [PATCH 3/8] [patch 2/7] vfs: mountinfo: add seq_file_root() Add a new function: seq_file_root() This is similar to seq_path(), but calculates the path relative to the given root, instead of current->fs->root. If the path was unreachable from root, then modify the root parameter to reflect this. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 24 ++++++++++++++++-------- fs/seq_file.c | 30 ++++++++++++++++++++++++++++++ include/linux/dcache.h | 1 + include/linux/seq_file.h | 2 ++ 4 files changed, 49 insertions(+), 8 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 635c2aa427ed..3ee588d5f585 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1759,10 +1759,8 @@ static int prepend(char **buffer, int *buflen, const char *str, /** * d_path - return the path of a dentry - * @dentry: dentry to report - * @vfsmnt: vfsmnt to which the dentry belongs - * @root: root dentry - * @rootmnt: vfsmnt to which the root dentry belongs + * @path: the dentry/vfsmount to report + * @root: root vfsmnt/dentry (may be modified by this function) * @buffer: buffer to return value in * @buflen: buffer length * @@ -1772,10 +1770,15 @@ static int prepend(char **buffer, int *buflen, const char *str, * Returns the buffer or an error code if the path was too long. * * "buflen" should be positive. Caller holds the dcache_lock. + * + * If path is not reachable from the supplied root, then the value of + * root is changed (without modifying refcounts). */ -static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt, - struct path *root, char *buffer, int buflen) +char *__d_path(const struct path *path, struct path *root, + char *buffer, int buflen) { + struct dentry *dentry = path->dentry; + struct vfsmount *vfsmnt = path->mnt; char * end = buffer+buflen; char * retval; @@ -1824,6 +1827,8 @@ global_root: if (prepend(&retval, &buflen, dentry->d_name.name, dentry->d_name.len) != 0) goto Elong; + root->mnt = vfsmnt; + root->dentry = dentry; return retval; Elong: return ERR_PTR(-ENAMETOOLONG); @@ -1846,6 +1851,7 @@ char *d_path(struct path *path, char *buf, int buflen) { char *res; struct path root; + struct path tmp; /* * We have various synthetic filesystems that never get mounted. On @@ -1862,7 +1868,8 @@ char *d_path(struct path *path, char *buf, int buflen) path_get(&root); read_unlock(¤t->fs->lock); spin_lock(&dcache_lock); - res = __d_path(path->dentry, path->mnt, &root, buf, buflen); + tmp = root; + res = __d_path(path, &tmp, buf, buflen); spin_unlock(&dcache_lock); path_put(&root); return res; @@ -1970,9 +1977,10 @@ asmlinkage long sys_getcwd(char __user *buf, unsigned long size) spin_lock(&dcache_lock); if (pwd.dentry->d_parent == pwd.dentry || !d_unhashed(pwd.dentry)) { unsigned long len; + struct path tmp = root; char * cwd; - cwd = __d_path(pwd.dentry, pwd.mnt, &root, page, PAGE_SIZE); + cwd = __d_path(&pwd, &tmp, page, PAGE_SIZE); spin_unlock(&dcache_lock); error = PTR_ERR(cwd); diff --git a/fs/seq_file.c b/fs/seq_file.c index ae59f5a6c5c1..3f54dbd6c49b 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -392,6 +392,36 @@ int seq_path(struct seq_file *m, struct path *path, char *esc) } EXPORT_SYMBOL(seq_path); +/* + * Same as seq_path, but relative to supplied root. + * + * root may be changed, see __d_path(). + */ +int seq_path_root(struct seq_file *m, struct path *path, struct path *root, + char *esc) +{ + int err = -ENAMETOOLONG; + if (m->count < m->size) { + char *s = m->buf + m->count; + char *p; + + spin_lock(&dcache_lock); + p = __d_path(path, root, s, m->size - m->count); + spin_unlock(&dcache_lock); + err = PTR_ERR(p); + if (!IS_ERR(p)) { + s = mangle_path(s, p, esc); + if (s) { + p = m->buf + m->count; + m->count = s - m->buf; + return 0; + } + } + } + m->count = m->size; + return err; +} + /* * returns the path of the 'dentry' from the root of its filesystem. */ diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 63960033b6f5..cfb1627ac51c 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -301,6 +301,7 @@ extern int d_validate(struct dentry *, struct dentry *); */ extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); +extern char *__d_path(const struct path *path, struct path *root, char *, int); extern char *d_path(struct path *, char *, int); extern char *dentry_path(struct dentry *, char *, int); diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index 11676ccef7b3..5b5369c3c209 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -46,6 +46,8 @@ int seq_printf(struct seq_file *, const char *, ...) int seq_path(struct seq_file *, struct path *, char *); int seq_dentry(struct seq_file *, struct dentry *, char *); +int seq_path_root(struct seq_file *m, struct path *path, struct path *root, + char *esc); int single_open(struct file *, int (*)(struct seq_file *, void *), void *); int single_release(struct inode *, struct file *); From 73cd49ecdde92fdce131938bdaff4993010d181b Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 26 Mar 2008 22:11:34 +0100 Subject: [PATCH 4/8] [patch 3/7] vfs: mountinfo: add mount ID Add a unique ID to each vfsmount using the IDR infrastructure. The identifiers are reused after the vfsmount is freed. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/namespace.c | 34 ++++++++++++++++++++++++++++++++++ include/linux/mount.h | 1 + 2 files changed, 35 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index 1bf302d0478b..8ca6317cb401 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include "pnode.h" @@ -39,6 +40,7 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); static int event; +static DEFINE_IDA(mnt_id_ida); static struct list_head *mount_hashtable __read_mostly; static struct kmem_cache *mnt_cache __read_mostly; @@ -58,10 +60,41 @@ static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) +/* allocation is serialized by namespace_sem */ +static int mnt_alloc_id(struct vfsmount *mnt) +{ + int res; + +retry: + ida_pre_get(&mnt_id_ida, GFP_KERNEL); + spin_lock(&vfsmount_lock); + res = ida_get_new(&mnt_id_ida, &mnt->mnt_id); + spin_unlock(&vfsmount_lock); + if (res == -EAGAIN) + goto retry; + + return res; +} + +static void mnt_free_id(struct vfsmount *mnt) +{ + spin_lock(&vfsmount_lock); + ida_remove(&mnt_id_ida, mnt->mnt_id); + spin_unlock(&vfsmount_lock); +} + struct vfsmount *alloc_vfsmnt(const char *name) { struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); if (mnt) { + int err; + + err = mnt_alloc_id(mnt); + if (err) { + kmem_cache_free(mnt_cache, mnt); + return NULL; + } + atomic_set(&mnt->mnt_count, 1); INIT_LIST_HEAD(&mnt->mnt_hash); INIT_LIST_HEAD(&mnt->mnt_child); @@ -353,6 +386,7 @@ EXPORT_SYMBOL(simple_set_mnt); void free_vfsmnt(struct vfsmount *mnt) { kfree(mnt->mnt_devname); + mnt_free_id(mnt); kmem_cache_free(mnt_cache, mnt); } diff --git a/include/linux/mount.h b/include/linux/mount.h index 87b24cea1863..f0dfb17ffccc 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -56,6 +56,7 @@ struct vfsmount { struct list_head mnt_slave; /* slave list entry */ struct vfsmount *mnt_master; /* slave is on master->mnt_slave_list */ struct mnt_namespace *mnt_ns; /* containing namespace */ + int mnt_id; /* mount identifier */ /* * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount * to let these frequently modified fields in a separate cache line From 719f5d7f0b90ac2c8f8ca4232eb322b266fea01e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 27 Mar 2008 13:06:23 +0100 Subject: [PATCH 5/8] [patch 4/7] vfs: mountinfo: add mount peer group ID Add a unique ID to each peer group using the IDR infrastructure. The identifiers are reused after the peer group dissolves. The IDR structures are protected by holding namepspace_sem for write while allocating or deallocating IDs. IDs are allocated when a previously unshared vfsmount becomes the first member of a peer group. When a new member is added to an existing group, the ID is copied from one of the old members. IDs are freed when the last member of a peer group is unshared. Setting the MNT_SHARED flag on members of a subtree is done as a separate step, after all the IDs have been allocated. This way an allocation failure can be cleaned up easilty, without affecting the propagation state. Based on design sketch by Al Viro. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/namespace.c | 93 +++++++++++++++++++++++++++++++++++++++++-- fs/pnode.c | 5 ++- include/linux/mount.h | 1 + 3 files changed, 95 insertions(+), 4 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 8ca6317cb401..cefa1d9939b0 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -41,6 +41,7 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); static int event; static DEFINE_IDA(mnt_id_ida); +static DEFINE_IDA(mnt_group_ida); static struct list_head *mount_hashtable __read_mostly; static struct kmem_cache *mnt_cache __read_mostly; @@ -83,6 +84,28 @@ static void mnt_free_id(struct vfsmount *mnt) spin_unlock(&vfsmount_lock); } +/* + * Allocate a new peer group ID + * + * mnt_group_ida is protected by namespace_sem + */ +static int mnt_alloc_group_id(struct vfsmount *mnt) +{ + if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) + return -ENOMEM; + + return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id); +} + +/* + * Release a peer group ID + */ +void mnt_release_group_id(struct vfsmount *mnt) +{ + ida_remove(&mnt_group_ida, mnt->mnt_group_id); + mnt->mnt_group_id = 0; +} + struct vfsmount *alloc_vfsmnt(const char *name) { struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); @@ -533,6 +556,17 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); if (mnt) { + if (flag & (CL_SLAVE | CL_PRIVATE)) + mnt->mnt_group_id = 0; /* not a peer of original */ + else + mnt->mnt_group_id = old->mnt_group_id; + + if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { + int err = mnt_alloc_group_id(mnt); + if (err) + goto out_free; + } + mnt->mnt_flags = old->mnt_flags; atomic_inc(&sb->s_active); mnt->mnt_sb = sb; @@ -562,6 +596,10 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, } } return mnt; + + out_free: + free_vfsmnt(mnt); + return NULL; } static inline void __mntput(struct vfsmount *mnt) @@ -1142,6 +1180,33 @@ void drop_collected_mounts(struct vfsmount *mnt) release_mounts(&umount_list); } +static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) +{ + struct vfsmount *p; + + for (p = mnt; p != end; p = next_mnt(p, mnt)) { + if (p->mnt_group_id && !IS_MNT_SHARED(p)) + mnt_release_group_id(p); + } +} + +static int invent_group_ids(struct vfsmount *mnt, bool recurse) +{ + struct vfsmount *p; + + for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { + if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { + int err = mnt_alloc_group_id(p); + if (err) { + cleanup_group_ids(mnt, p); + return err; + } + } + } + + return 0; +} + /* * @source_mnt : mount tree to be attached * @nd : place the mount tree @source_mnt is attached @@ -1212,9 +1277,16 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, struct vfsmount *dest_mnt = path->mnt; struct dentry *dest_dentry = path->dentry; struct vfsmount *child, *p; + int err; - if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) - return -EINVAL; + if (IS_MNT_SHARED(dest_mnt)) { + err = invent_group_ids(source_mnt, true); + if (err) + goto out; + } + err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); + if (err) + goto out_cleanup_ids; if (IS_MNT_SHARED(dest_mnt)) { for (p = source_mnt; p; p = next_mnt(p, source_mnt)) @@ -1237,6 +1309,12 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, } spin_unlock(&vfsmount_lock); return 0; + + out_cleanup_ids: + if (IS_MNT_SHARED(dest_mnt)) + cleanup_group_ids(source_mnt, NULL); + out: + return err; } static int graft_tree(struct vfsmount *mnt, struct path *path) @@ -1277,6 +1355,7 @@ static noinline int do_change_type(struct nameidata *nd, int flag) struct vfsmount *m, *mnt = nd->path.mnt; int recurse = flag & MS_REC; int type = flag & ~MS_REC; + int err = 0; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -1285,12 +1364,20 @@ static noinline int do_change_type(struct nameidata *nd, int flag) return -EINVAL; down_write(&namespace_sem); + if (type == MS_SHARED) { + err = invent_group_ids(mnt, recurse); + if (err) + goto out_unlock; + } + spin_lock(&vfsmount_lock); for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) change_mnt_propagation(m, type); spin_unlock(&vfsmount_lock); + + out_unlock: up_write(&namespace_sem); - return 0; + return err; } /* diff --git a/fs/pnode.c b/fs/pnode.c index f968e35d9785..d18d66491a01 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -46,7 +46,11 @@ static int do_make_slave(struct vfsmount *mnt) if (peer_mnt == mnt) peer_mnt = NULL; } + if (IS_MNT_SHARED(mnt) && list_empty(&mnt->mnt_share)) + mnt_release_group_id(mnt); + list_del_init(&mnt->mnt_share); + mnt->mnt_group_id = 0; if (peer_mnt) master = peer_mnt; @@ -68,7 +72,6 @@ static int do_make_slave(struct vfsmount *mnt) } mnt->mnt_master = master; CLEAR_MNT_SHARED(mnt); - INIT_LIST_HEAD(&mnt->mnt_slave_list); return 0; } diff --git a/include/linux/mount.h b/include/linux/mount.h index f0dfb17ffccc..b4836d58f428 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -57,6 +57,7 @@ struct vfsmount { struct vfsmount *mnt_master; /* slave is on master->mnt_slave_list */ struct mnt_namespace *mnt_ns; /* containing namespace */ int mnt_id; /* mount identifier */ + int mnt_group_id; /* peer group identifier */ /* * We put mnt_count & mnt_expiry_mark at the end of struct vfsmount * to let these frequently modified fields in a separate cache line From a1a2c409b666befc58c2db9c7fbddf200f153470 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 27 Mar 2008 13:06:24 +0100 Subject: [PATCH 6/8] [patch 5/7] vfs: mountinfo: allow using process root Allow /proc//mountinfo to use the root of to calculate mountpoints. - move definition of 'struct proc_mounts' to - add the process's namespace and root to this structure - pass a pointer to 'struct proc_mounts' into seq_operations In addition the following cleanups are made: - use a common open function for /proc//{mounts,mountstat} - surround namespace.c part of these proc files with #ifdef CONFIG_PROC_FS - make the seq_operations structures const Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/namespace.c | 14 +++-- fs/proc/base.c | 108 ++++++++++++++++------------------ include/linux/mnt_namespace.h | 11 ++++ 3 files changed, 70 insertions(+), 63 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index cefa1d9939b0..dfdf51e81c1c 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -724,20 +724,21 @@ void save_mount_options(struct super_block *sb, char *options) } EXPORT_SYMBOL(save_mount_options); +#ifdef CONFIG_PROC_FS /* iterator */ static void *m_start(struct seq_file *m, loff_t *pos) { - struct mnt_namespace *n = m->private; + struct proc_mounts *p = m->private; down_read(&namespace_sem); - return seq_list_start(&n->list, *pos); + return seq_list_start(&p->ns->list, *pos); } static void *m_next(struct seq_file *m, void *v, loff_t *pos) { - struct mnt_namespace *n = m->private; + struct proc_mounts *p = m->private; - return seq_list_next(v, &n->list, pos); + return seq_list_next(v, &p->ns->list, pos); } static void m_stop(struct seq_file *m, void *v) @@ -794,7 +795,7 @@ static int show_vfsmnt(struct seq_file *m, void *v) return err; } -struct seq_operations mounts_op = { +const struct seq_operations mounts_op = { .start = m_start, .next = m_next, .stop = m_stop, @@ -833,12 +834,13 @@ static int show_vfsstat(struct seq_file *m, void *v) return err; } -struct seq_operations mountstats_op = { +const struct seq_operations mountstats_op = { .start = m_start, .next = m_next, .stop = m_stop, .show = show_vfsstat, }; +#endif /* CONFIG_PROC_FS */ /** * may_umount_tree - check if a mount tree is busy diff --git a/fs/proc/base.c b/fs/proc/base.c index 7313c62e3e9d..a04b3db7a296 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -502,17 +502,14 @@ static const struct inode_operations proc_def_inode_operations = { .setattr = proc_setattr, }; -extern const struct seq_operations mounts_op; -struct proc_mounts { - struct seq_file m; - int event; -}; - -static int mounts_open(struct inode *inode, struct file *file) +static int mounts_open_common(struct inode *inode, struct file *file, + const struct seq_operations *op) { struct task_struct *task = get_proc_task(inode); struct nsproxy *nsp; struct mnt_namespace *ns = NULL; + struct fs_struct *fs = NULL; + struct path root; struct proc_mounts *p; int ret = -EINVAL; @@ -525,40 +522,61 @@ static int mounts_open(struct inode *inode, struct file *file) get_mnt_ns(ns); } rcu_read_unlock(); - + if (ns) + fs = get_fs_struct(task); put_task_struct(task); } - if (ns) { - ret = -ENOMEM; - p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL); - if (p) { - file->private_data = &p->m; - ret = seq_open(file, &mounts_op); - if (!ret) { - p->m.private = ns; - p->event = ns->event; - return 0; - } - kfree(p); - } - put_mnt_ns(ns); - } + if (!ns) + goto err; + if (!fs) + goto err_put_ns; + + read_lock(&fs->lock); + root = fs->root; + path_get(&root); + read_unlock(&fs->lock); + put_fs_struct(fs); + + ret = -ENOMEM; + p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL); + if (!p) + goto err_put_path; + + file->private_data = &p->m; + ret = seq_open(file, op); + if (ret) + goto err_free; + + p->m.private = p; + p->ns = ns; + p->root = root; + p->event = ns->event; + + return 0; + + err_free: + kfree(p); + err_put_path: + path_put(&root); + err_put_ns: + put_mnt_ns(ns); + err: return ret; } static int mounts_release(struct inode *inode, struct file *file) { - struct seq_file *m = file->private_data; - struct mnt_namespace *ns = m->private; - put_mnt_ns(ns); + struct proc_mounts *p = file->private_data; + path_put(&p->root); + put_mnt_ns(p->ns); return seq_release(inode, file); } static unsigned mounts_poll(struct file *file, poll_table *wait) { struct proc_mounts *p = file->private_data; - struct mnt_namespace *ns = p->m.private; + struct mnt_namespace *ns = p->ns; unsigned res = 0; poll_wait(file, &ns->poll, wait); @@ -573,6 +591,11 @@ static unsigned mounts_poll(struct file *file, poll_table *wait) return res; } +static int mounts_open(struct inode *inode, struct file *file) +{ + return mounts_open_common(inode, file, &mounts_op); +} + static const struct file_operations proc_mounts_operations = { .open = mounts_open, .read = seq_read, @@ -581,38 +604,9 @@ static const struct file_operations proc_mounts_operations = { .poll = mounts_poll, }; -extern const struct seq_operations mountstats_op; static int mountstats_open(struct inode *inode, struct file *file) { - int ret = seq_open(file, &mountstats_op); - - if (!ret) { - struct seq_file *m = file->private_data; - struct nsproxy *nsp; - struct mnt_namespace *mnt_ns = NULL; - struct task_struct *task = get_proc_task(inode); - - if (task) { - rcu_read_lock(); - nsp = task_nsproxy(task); - if (nsp) { - mnt_ns = nsp->mnt_ns; - if (mnt_ns) - get_mnt_ns(mnt_ns); - } - rcu_read_unlock(); - - put_task_struct(task); - } - - if (mnt_ns) - m->private = mnt_ns; - else { - seq_release(inode, file); - ret = -EINVAL; - } - } - return ret; + return mounts_open_common(inode, file, &mountstats_op); } static const struct file_operations proc_mountstats_operations = { diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h index 8eed44f8ca73..c078aacc8116 100644 --- a/include/linux/mnt_namespace.h +++ b/include/linux/mnt_namespace.h @@ -5,6 +5,7 @@ #include #include #include +#include struct mnt_namespace { atomic_t count; @@ -14,6 +15,13 @@ struct mnt_namespace { int event; }; +struct proc_mounts { + struct seq_file m; /* must be the first element */ + struct mnt_namespace *ns; + struct path root; + int event; +}; + extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *, struct fs_struct *); extern void __put_mnt_ns(struct mnt_namespace *ns); @@ -37,5 +45,8 @@ static inline void get_mnt_ns(struct mnt_namespace *ns) atomic_inc(&ns->count); } +extern const struct seq_operations mounts_op; +extern const struct seq_operations mountstats_op; + #endif #endif From 2d4d4864ac08caff5c204a752bd004eed4f08760 Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Thu, 27 Mar 2008 13:06:25 +0100 Subject: [PATCH 7/8] [patch 6/7] vfs: mountinfo: add /proc//mountinfo [mszeredi@suse.cz] rewrite and split big patch into managable chunks /proc/mounts in its current form lacks important information: - propagation state - root of mount for bind mounts - the st_dev value used within the filesystem - identifier for each mount and it's parent It also suffers from the following problems: - not easily extendable - ambiguity of mountpoints within a chrooted environment - doesn't distinguish between filesystem dependent and independent options - doesn't distinguish between per mount and per super block options This patch introduces /proc//mountinfo which attempts to address all these deficiencies. Code shared between /proc//mounts and /proc//mountinfo is extracted into separate functions. Thanks to Al Viro for the help in getting the design right. Signed-off-by: Ram Pai Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- Documentation/filesystems/proc.txt | 32 ++++++++ fs/namespace.c | 119 +++++++++++++++++++++++------ fs/proc/base.c | 15 ++++ include/linux/mnt_namespace.h | 1 + 4 files changed, 144 insertions(+), 23 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 518ebe609e2b..2cd920f92e5e 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -43,6 +43,7 @@ Table of Contents 2.13 /proc//oom_score - Display current oom-killer score 2.14 /proc//io - Display the IO accounting fields 2.15 /proc//coredump_filter - Core dump filtering settings + 2.16 /proc//mountinfo - Information about mounts ------------------------------------------------------------------------------ Preface @@ -2348,4 +2349,35 @@ For example: $ echo 0x7 > /proc/self/coredump_filter $ ./some_program +2.16 /proc//mountinfo - Information about mounts +-------------------------------------------------------- + +This file contains lines of the form: + +36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue +(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) + +(1) mount ID: unique identifier of the mount (may be reused after umount) +(2) parent ID: ID of parent (or of self for the top of the mount tree) +(3) major:minor: value of st_dev for files on filesystem +(4) root: root of the mount within the filesystem +(5) mount point: mount point relative to the process's root +(6) mount options: per mount options +(7) optional fields: zero or more fields of the form "tag[:value]" +(8) separator: marks the end of the optional fields +(9) filesystem type: name of filesystem of the form "type[.subtype]" +(10) mount source: filesystem specific information or "none" +(11) super options: per super block options + +Parsers should ignore all unrecognised optional fields. Currently the +possible optional fields are: + +shared:X mount is shared in peer group X +master:X mount is slave to peer group X +unbindable mount is unbindable + +For more information on mount propagation see: + + Documentation/filesystems/sharedsubtree.txt + ------------------------------------------------------------------------------ diff --git a/fs/namespace.c b/fs/namespace.c index dfdf51e81c1c..c807b8d5f891 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -746,20 +746,30 @@ static void m_stop(struct seq_file *m, void *v) up_read(&namespace_sem); } -static int show_vfsmnt(struct seq_file *m, void *v) +struct proc_fs_info { + int flag; + const char *str; +}; + +static void show_sb_opts(struct seq_file *m, struct super_block *sb) { - struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); - int err = 0; - static struct proc_fs_info { - int flag; - char *str; - } fs_info[] = { + static const struct proc_fs_info fs_info[] = { { MS_SYNCHRONOUS, ",sync" }, { MS_DIRSYNC, ",dirsync" }, { MS_MANDLOCK, ",mand" }, { 0, NULL } }; - static struct proc_fs_info mnt_info[] = { + const struct proc_fs_info *fs_infop; + + for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { + if (sb->s_flags & fs_infop->flag) + seq_puts(m, fs_infop->str); + } +} + +static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) +{ + static const struct proc_fs_info mnt_info[] = { { MNT_NOSUID, ",nosuid" }, { MNT_NODEV, ",nodev" }, { MNT_NOEXEC, ",noexec" }, @@ -768,27 +778,37 @@ static int show_vfsmnt(struct seq_file *m, void *v) { MNT_RELATIME, ",relatime" }, { 0, NULL } }; - struct proc_fs_info *fs_infop; + const struct proc_fs_info *fs_infop; + + for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { + if (mnt->mnt_flags & fs_infop->flag) + seq_puts(m, fs_infop->str); + } +} + +static void show_type(struct seq_file *m, struct super_block *sb) +{ + mangle(m, sb->s_type->name); + if (sb->s_subtype && sb->s_subtype[0]) { + seq_putc(m, '.'); + mangle(m, sb->s_subtype); + } +} + +static int show_vfsmnt(struct seq_file *m, void *v) +{ + struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); + int err = 0; struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); seq_putc(m, ' '); seq_path(m, &mnt_path, " \t\n\\"); seq_putc(m, ' '); - mangle(m, mnt->mnt_sb->s_type->name); - if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) { - seq_putc(m, '.'); - mangle(m, mnt->mnt_sb->s_subtype); - } + show_type(m, mnt->mnt_sb); seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); - for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { - if (mnt->mnt_sb->s_flags & fs_infop->flag) - seq_puts(m, fs_infop->str); - } - for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { - if (mnt->mnt_flags & fs_infop->flag) - seq_puts(m, fs_infop->str); - } + show_sb_opts(m, mnt->mnt_sb); + show_mnt_opts(m, mnt); if (mnt->mnt_sb->s_op->show_options) err = mnt->mnt_sb->s_op->show_options(m, mnt); seq_puts(m, " 0 0\n"); @@ -802,6 +822,59 @@ const struct seq_operations mounts_op = { .show = show_vfsmnt }; +static int show_mountinfo(struct seq_file *m, void *v) +{ + struct proc_mounts *p = m->private; + struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); + struct super_block *sb = mnt->mnt_sb; + struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; + struct path root = p->root; + int err = 0; + + seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, + MAJOR(sb->s_dev), MINOR(sb->s_dev)); + seq_dentry(m, mnt->mnt_root, " \t\n\\"); + seq_putc(m, ' '); + seq_path_root(m, &mnt_path, &root, " \t\n\\"); + if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { + /* + * Mountpoint is outside root, discard that one. Ugly, + * but less so than trying to do that in iterator in a + * race-free way (due to renames). + */ + return SEQ_SKIP; + } + seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); + show_mnt_opts(m, mnt); + + /* Tagged fields ("foo:X" or "bar") */ + if (IS_MNT_SHARED(mnt)) + seq_printf(m, " shared:%i", mnt->mnt_group_id); + if (IS_MNT_SLAVE(mnt)) + seq_printf(m, " master:%i", mnt->mnt_master->mnt_group_id); + if (IS_MNT_UNBINDABLE(mnt)) + seq_puts(m, " unbindable"); + + /* Filesystem specific data */ + seq_puts(m, " - "); + show_type(m, sb); + seq_putc(m, ' '); + mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); + seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); + show_sb_opts(m, sb); + if (sb->s_op->show_options) + err = sb->s_op->show_options(m, mnt); + seq_putc(m, '\n'); + return err; +} + +const struct seq_operations mountinfo_op = { + .start = m_start, + .next = m_next, + .stop = m_stop, + .show = show_mountinfo, +}; + static int show_vfsstat(struct seq_file *m, void *v) { struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); @@ -822,7 +895,7 @@ static int show_vfsstat(struct seq_file *m, void *v) /* file system type */ seq_puts(m, "with fstype "); - mangle(m, mnt->mnt_sb->s_type->name); + show_type(m, mnt->mnt_sb); /* optional statistics */ if (mnt->mnt_sb->s_op->show_stats) { diff --git a/fs/proc/base.c b/fs/proc/base.c index a04b3db7a296..c5e412a00b17 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -604,6 +604,19 @@ static const struct file_operations proc_mounts_operations = { .poll = mounts_poll, }; +static int mountinfo_open(struct inode *inode, struct file *file) +{ + return mounts_open_common(inode, file, &mountinfo_op); +} + +static const struct file_operations proc_mountinfo_operations = { + .open = mountinfo_open, + .read = seq_read, + .llseek = seq_lseek, + .release = mounts_release, + .poll = mounts_poll, +}; + static int mountstats_open(struct inode *inode, struct file *file) { return mounts_open_common(inode, file, &mountstats_op); @@ -2303,6 +2316,7 @@ static const struct pid_entry tgid_base_stuff[] = { LNK("root", root), LNK("exe", exe), REG("mounts", S_IRUGO, mounts), + REG("mountinfo", S_IRUGO, mountinfo), REG("mountstats", S_IRUSR, mountstats), #ifdef CONFIG_PROC_PAGE_MONITOR REG("clear_refs", S_IWUSR, clear_refs), @@ -2635,6 +2649,7 @@ static const struct pid_entry tid_base_stuff[] = { LNK("root", root), LNK("exe", exe), REG("mounts", S_IRUGO, mounts), + REG("mountinfo", S_IRUGO, mountinfo), #ifdef CONFIG_PROC_PAGE_MONITOR REG("clear_refs", S_IWUSR, clear_refs), REG("smaps", S_IRUGO, smaps), diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h index c078aacc8116..830bbcd449d6 100644 --- a/include/linux/mnt_namespace.h +++ b/include/linux/mnt_namespace.h @@ -46,6 +46,7 @@ static inline void get_mnt_ns(struct mnt_namespace *ns) } extern const struct seq_operations mounts_op; +extern const struct seq_operations mountinfo_op; extern const struct seq_operations mountstats_op; #endif From 97e7e0f71d6d948c25f11f0a33878d9356d9579e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 27 Mar 2008 13:06:26 +0100 Subject: [PATCH 8/8] [patch 7/7] vfs: mountinfo: show dominating group id Show peer group ID of nearest dominating group that has intersection with the mount's namespace. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- Documentation/filesystems/proc.txt | 6 ++++ fs/namespace.c | 9 ++++-- fs/pnode.c | 51 ++++++++++++++++++++++++++++++ fs/pnode.h | 1 + 4 files changed, 65 insertions(+), 2 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 2cd920f92e5e..2a99116edc47 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -2374,8 +2374,14 @@ possible optional fields are: shared:X mount is shared in peer group X master:X mount is slave to peer group X +propagate_from:X mount is slave and receives propagation from peer group X (*) unbindable mount is unbindable +(*) X is the closest dominant peer group under the process's root. If +X is the immediate master of the mount, or if there's no dominant peer +group under the same root, then only the "master:X" field is present +and not the "propagate_from:X" field. + For more information on mount propagation see: Documentation/filesystems/sharedsubtree.txt diff --git a/fs/namespace.c b/fs/namespace.c index c807b8d5f891..0505fb61aa74 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -850,8 +850,13 @@ static int show_mountinfo(struct seq_file *m, void *v) /* Tagged fields ("foo:X" or "bar") */ if (IS_MNT_SHARED(mnt)) seq_printf(m, " shared:%i", mnt->mnt_group_id); - if (IS_MNT_SLAVE(mnt)) - seq_printf(m, " master:%i", mnt->mnt_master->mnt_group_id); + if (IS_MNT_SLAVE(mnt)) { + int master = mnt->mnt_master->mnt_group_id; + int dom = get_dominating_id(mnt, &p->root); + seq_printf(m, " master:%i", master); + if (dom && dom != master) + seq_printf(m, " propagate_from:%i", dom); + } if (IS_MNT_UNBINDABLE(mnt)) seq_puts(m, " unbindable"); diff --git a/fs/pnode.c b/fs/pnode.c index d18d66491a01..8d5f392ec3d3 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -28,6 +28,57 @@ static inline struct vfsmount *next_slave(struct vfsmount *p) return list_entry(p->mnt_slave.next, struct vfsmount, mnt_slave); } +/* + * Return true if path is reachable from root + * + * namespace_sem is held, and mnt is attached + */ +static bool is_path_reachable(struct vfsmount *mnt, struct dentry *dentry, + const struct path *root) +{ + while (mnt != root->mnt && mnt->mnt_parent != mnt) { + dentry = mnt->mnt_mountpoint; + mnt = mnt->mnt_parent; + } + return mnt == root->mnt && is_subdir(dentry, root->dentry); +} + +static struct vfsmount *get_peer_under_root(struct vfsmount *mnt, + struct mnt_namespace *ns, + const struct path *root) +{ + struct vfsmount *m = mnt; + + do { + /* Check the namespace first for optimization */ + if (m->mnt_ns == ns && is_path_reachable(m, m->mnt_root, root)) + return m; + + m = next_peer(m); + } while (m != mnt); + + return NULL; +} + +/* + * Get ID of closest dominating peer group having a representative + * under the given root. + * + * Caller must hold namespace_sem + */ +int get_dominating_id(struct vfsmount *mnt, const struct path *root) +{ + struct vfsmount *m; + + for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) { + struct vfsmount *d = get_peer_under_root(m, mnt->mnt_ns, root); + if (d) + return d->mnt_group_id; + } + + return 0; +} + static int do_make_slave(struct vfsmount *mnt) { struct vfsmount *peer_mnt = mnt, *master = mnt->mnt_master; diff --git a/fs/pnode.h b/fs/pnode.h index 973c3f825e7d..958665d662af 100644 --- a/fs/pnode.h +++ b/fs/pnode.h @@ -36,4 +36,5 @@ int propagate_mnt(struct vfsmount *, struct dentry *, struct vfsmount *, int propagate_umount(struct list_head *); int propagate_mount_busy(struct vfsmount *, int); void mnt_release_group_id(struct vfsmount *); +int get_dominating_id(struct vfsmount *mnt, const struct path *root); #endif /* _LINUX_PNODE_H */