From: David Howells dhowells@redhat.com
[ Upstream commit dd7bc8158b413e0b580c491e8bd18cb91057c7c2 ]
Commit 6fcf0c72e4b9, a fix to get_tree_bdev() put a missing blkdev_put() in the wrong place, before a warnf() that displays the bdev under consideration rather after it.
This results in a silent lockup in printk("%pg") called via warnf() from get_tree_bdev() under some circumstances when there's a race with the blockdev being frozen. This can be caused by xfstests/tests/generic/085 in combination with Lukas Czerner's ext4 mount API conversion patchset. It looks like it ought to occur with other users of get_tree_bdev() such as XFS, but apparently doesn't.
Fix this by switching the order of the lines.
Fixes: 6fcf0c72e4b9 ("vfs: add missing blkdev_put() in get_tree_bdev()") Reported-by: Lukas Czerner lczerner@redhat.com Signed-off-by: David Howells dhowells@redhat.com cc: Ian Kent raven@themaw.net cc: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/super.c b/fs/super.c index cd352530eca90..a288cd60d2aed 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1302,8 +1302,8 @@ int get_tree_bdev(struct fs_context *fc, mutex_lock(&bdev->bd_fsfreeze_mutex); if (bdev->bd_fsfreeze_count > 0) { mutex_unlock(&bdev->bd_fsfreeze_mutex); - blkdev_put(bdev, mode); warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); + blkdev_put(bdev, mode); return -EBUSY; }