From: Josef Bacik josef@toxicpanda.com
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@vger.kernel.org # 4.14+ Signed-off-by: Josef Bacik josef@toxicpanda.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -4138,8 +4138,11 @@ 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);