From: Josef Bacik <josef@xxxxxxxxxxxxxx>
commit 92fb94b69c6accf1e49fff699640fa0ce03dc910 upstream.
We set cache_block_group_error if btrfs_cache_block_group() returns an
error, this is because we could end up not finding space to allocate and
mistakenly return -ENOSPC, and which could then abort the transaction
with the incorrect errno, and in the case of ENOSPC result in a
WARN_ON() that will trip up tests like generic/475.
However there's the case where multiple threads can be racing, one
thread gets the proper error, and the other thread doesn't actually call
btrfs_cache_block_group(), it instead sees ->cached ==
BTRFS_CACHE_ERROR. Again the result is the same, we fail to allocate
our space and return -ENOSPC. Instead we need to set
cache_block_group_error to -EIO in this case to make sure that if we do
not make our allocation we get the appropriate error returned back to
the caller.
CC: stable@xxxxxxxxxxxxxxx # 4.14+
Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/extent-tree.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4411,8 +4411,11 @@ have_block_group:
ret = 0;
}
- if (unlikely(block_group->cached == BTRFS_CACHE_ERROR))
+ if (unlikely(block_group->cached == BTRFS_CACHE_ERROR)) {
+ if (!cache_block_group_error)
+ cache_block_group_error = -EIO;
goto loop;
+ }
bg_ret = NULL;
ret = do_allocation(block_group, ffe_ctl, &bg_ret);
