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vfs: keep list of mounts for each superblock

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Keep track of vfsmounts belonging to a superblock.  List is protected
by vfsmount_lock.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Miklos Szeredi 2011-11-21 12:11:30 +01:00 committed by Al Viro
parent 34c80b1d93
commit 39f7c4db1d
4 changed files with 11 additions and 0 deletions
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1
fs/mount.h
View file

@ -29,6 +29,7 @@ struct mount {
#endif
struct list_head mnt_mounts; /* list of children, anchored here */
struct list_head mnt_child; /* and going through their mnt_child */
struct list_head mnt_instance; /* mount instance on sb->s_mounts */
const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
struct list_head mnt_list;
struct list_head mnt_expire; /* link in fs-specific expiry list */

7
fs/namespace.c
View file

@ -671,6 +671,9 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
mnt->mnt.mnt_sb = root->d_sb;
mnt->mnt_mountpoint = mnt->mnt.mnt_root;
mnt->mnt_parent = mnt;
br_write_lock(vfsmount_lock);
list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts);
br_write_unlock(vfsmount_lock);
return &mnt->mnt;
}
EXPORT_SYMBOL_GPL(vfs_kern_mount);
@ -699,6 +702,9 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
mnt->mnt.mnt_root = dget(root);
mnt->mnt_mountpoint = mnt->mnt.mnt_root;
mnt->mnt_parent = mnt;
br_write_lock(vfsmount_lock);
list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
br_write_unlock(vfsmount_lock);
if (flag & CL_SLAVE) {
list_add(&mnt->mnt_slave, &old->mnt_slave_list);
@ -781,6 +787,7 @@ static void mntput_no_expire(struct mount *mnt)
acct_auto_close_mnt(&mnt->mnt);
goto put_again;
}
list_del(&mnt->mnt_instance);
br_write_unlock(vfsmount_lock);
mntfree(mnt);
}

2
fs/super.c
View file

@ -142,6 +142,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
INIT_LIST_HEAD(&s->s_dentry_lru);
INIT_LIST_HEAD(&s->s_inode_lru);
spin_lock_init(&s->s_inode_lru_lock);
INIT_LIST_HEAD(&s->s_mounts);
init_rwsem(&s->s_umount);
mutex_init(&s->s_lock);
lockdep_set_class(&s->s_umount, &type->s_umount_key);
@ -200,6 +201,7 @@ static inline void destroy_super(struct super_block *s)
free_percpu(s->s_files);
#endif
security_sb_free(s);
WARN_ON(!list_empty(&s->s_mounts));
kfree(s->s_subtype);
kfree(s->s_options);
kfree(s);

1
include/linux/fs.h
View file

@ -1428,6 +1428,7 @@ struct super_block {
#else
struct list_head s_files;
#endif
struct list_head s_mounts; /* list of mounts; _not_ for fs use */
/* s_dentry_lru, s_nr_dentry_unused protected by dcache.c lru locks */
struct list_head s_dentry_lru; /* unused dentry lru */
int s_nr_dentry_unused; /* # of dentry on lru */