diff options
| author | Jan Kara <jack@suse.cz> | 2012-02-10 11:03:00 +0100 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-02-13 20:45:38 -0500 |
| commit | 6b6dc836a195e077e76977b6c020a73de411b46d (patch) | |
| tree | 59920a3aab6db4997f6b7a95c753219bdc12bd64 | |
| parent | 074b85175a43a23fdbde60f55feea636e0bf0f85 (diff) | |
vfs: Provide function to get superblock and wait for it to thaw
In quota code we need to find a superblock corresponding to a device and wait
for superblock to be unfrozen. However this waiting has to happen without
s_umount semaphore because that is required for superblock to thaw. So provide
a function in VFS for this to keep dances with s_umount where they belong.
[AV: implementation switched to saner variant]
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/super.c | 22 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 |
2 files changed, 23 insertions, 0 deletions
diff --git a/fs/super.c b/fs/super.c index 6015c02296b..6277ec6cb60 100644 --- a/fs/super.c +++ b/fs/super.c @@ -634,6 +634,28 @@ rescan: EXPORT_SYMBOL(get_super); /** + * get_super_thawed - get thawed superblock of a device + * @bdev: device to get the superblock for + * + * Scans the superblock list and finds the superblock of the file system + * mounted on the device. The superblock is returned once it is thawed + * (or immediately if it was not frozen). %NULL is returned if no match + * is found. + */ +struct super_block *get_super_thawed(struct block_device *bdev) +{ + while (1) { + struct super_block *s = get_super(bdev); + if (!s || s->s_frozen == SB_UNFROZEN) + return s; + up_read(&s->s_umount); + vfs_check_frozen(s, SB_FREEZE_WRITE); + put_super(s); + } +} +EXPORT_SYMBOL(get_super_thawed); + +/** * get_active_super - get an active reference to the superblock of a device * @bdev: device to get the superblock for * diff --git a/include/linux/fs.h b/include/linux/fs.h index 386da09f229..69cd5bb640f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2496,6 +2496,7 @@ extern void get_filesystem(struct file_system_type *fs); extern void put_filesystem(struct file_system_type *fs); extern struct file_system_type *get_fs_type(const char *name); extern struct super_block *get_super(struct block_device *); +extern struct super_block *get_super_thawed(struct block_device *); extern struct super_block *get_active_super(struct block_device *bdev); extern void drop_super(struct super_block *sb); extern void iterate_supers(void (*)(struct super_block *, void *), void *); |