[PATCH AUTOSEL 4.14 293/371] Btrfs: fix inode cache waiters hanging on path allocation failure

Sasha Levin
2020-01-16T18:16:37Z

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit 9d123a35d7e97bb2139747b16127c9b22b6a593e ]

If the caching thread fails to allocate a path, it returns without waking
up any cache waiters, leaving them hang forever. Fix this by following the
same approach as when we fail to start the caching thread: print an error
message, disable inode caching and make the wakers fallback to non-caching
mode behaviour (calling btrfs_find_free_objectid()).

Fixes: 581bb050941b4f ("Btrfs: Cache free inode numbers in memory")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/inode-map.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index b1c3a4ec76c8..2ae32451fb5b 100644
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -55,8 +55,10 @@ static int caching_kthread(void *data)
return 0;

path = btrfs_alloc_path();
- if (!path)
+ if (!path) {
+ fail_caching_thread(root);
return -ENOMEM;
+ }

/* Since the commit root is read-only, we can safely skip locking. */
path->skip_locking = 1;
--
2.20.1