From 6b6dc836a195e077e76977b6c020a73de411b46d Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 10 Feb 2012 11:03:00 +0100 Subject: 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 Signed-off-by: Al Viro --- fs/super.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index 6015c02296b7..6277ec6cb60a 100644 --- a/fs/super.c +++ b/fs/super.c @@ -633,6 +633,28 @@ 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 -- cgit v1.2.3-55-g7522