Commit 82323b1a authored by Mark Harmstone's avatar Mark Harmstone Committed by David Sterba
Browse files

btrfs: fix double-decrement of bytes_may_use in submit_one_async_extent() 



submit_one_async_extent() calls btrfs_reserve_extent(), which decrements
bytes_may_use. If the call btrfs_create_io_em() fails, we jump to
out_free_reserve, which calls extent_clear_unlock_delalloc().

Because we're specifying EXTENT_DO_ACCOUNTING, i.e.
EXTENT_CLEAR_META_RESV | EXTENT_CLEAR_DATA_RESV, this decreases
bytes_may_use again. This can lead to problems later on, as an initial
write can fail only for the writeback to silently ENOSPC.

Fix this by replacing EXTENT_DO_ACCOUNTING with EXTENT_CLEAR_META_RESV.
This parallels a4fe134f ("btrfs: fix a double release on reserved
extents in cow_one_range()"), which is the same fix in cow_one_range().

Fixes: 151a41bc ("Btrfs: fix what bits we clear when erroring out from delalloc")
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarMark Harmstone <mark@harmstone.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent a8d58a7c

fs/btrfs/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -1153,7 +1153,7 @@ static void submit_one_async_extent(struct async_chunk *async_chunk, 
				     NULL, &cached,

				     EXTENT_LOCKED | EXTENT_DELALLOC |

				     EXTENT_DELALLOC_NEW |

				     EXTENT_DEFRAG | EXTENT_DO_ACCOUNTING,

				     EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV,

				     PAGE_UNLOCK | PAGE_START_WRITEBACK |

				     PAGE_END_WRITEBACK);

	if (async_extent->cb)