From: Josef Bacik <jbacik@fb.com>
Date: Wed, 15 Nov 2017 21:20:52 +0000 (-0500)
Subject: btrfs: fix deadlock when writing out space cache
X-Git-Tag: v4.14.17~86
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=928066e61940e3c19f85d543d15c55fcae20208f;p=platform%2Fkernel%2Flinux-exynos.git

btrfs: fix deadlock when writing out space cache


[ Upstream commit b77000ed558daa3bef0899d29bf171b8c9b5e6a8 ]

If we fail to prepare our pages for whatever reason (out of memory in
our case) we need to make sure to drop the block_group->data_rwsem,
otherwise hilarity ensues.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add label and use existing unlocking code ]
Signed-off-by: David Sterba <dsterba@suse.com>

Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index cdc9f4015ec3..4426d1c73e50 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1264,7 +1264,7 @@ static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 	/* Lock all pages first so we can lock the extent safely. */
 	ret = io_ctl_prepare_pages(io_ctl, inode, 0);
 	if (ret)
-		goto out;
+		goto out_unlock;
 
 	lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 			 &cached_state);
@@ -1358,6 +1358,7 @@ out_nospc_locked:
 out_nospc:
 	cleanup_write_cache_enospc(inode, io_ctl, &cached_state);
 
+out_unlock:
 	if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
 		up_write(&block_group->data_rwsem);