[PATCH 2/5] btrfs: clear dirty blocks after a delalloc failure

[Josef Bacik]

If writepage_delalloc() runs the first delalloc ranges of a folio and
then btrfs_run_delalloc_range() fails, the blocks that already got an
ordered extent are finished with an error through
btrfs_mark_ordered_io_finished(), but their dirty bits are left set. The
next writeback then submits blocks whose ordered extent is gone, or is
about to be completed a second time.

Fix by clearing the dirty bits and cycling the writeback state for those
blocks, as submit_write_sector() does for a block it fails to submit.

Fixes: 72dad8e377af ("btrfs: fix double accounting race when btrfs_run_delalloc_range() failed")
CC: stable@xxxxxxxxxxxxxxx # 6.14+
Assisted-by: LLM
Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
---
 fs/btrfs/extent_io.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 5ff630630490..3283835ccb5e 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1746,6 +1746,16 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
 			u64 start = page_start + (start_bit << fs_info->sectorsize_bits);
 			u32 len = (end_bit - start_bit) << fs_info->sectorsize_bits;
 
+			/*
+			 * The blocks are not going to be submitted, so they
+			 * must not stay dirty. Otherwise they are written back
+			 * later without an ordered extent, or worse, with this
+			 * one if it is still around, and invalidating the folio
+			 * would account for them again.
+			 */
+			btrfs_folio_clear_dirty(fs_info, folio, start, len);
+			btrfs_folio_set_writeback(fs_info, folio, start, len);
+			btrfs_folio_clear_writeback(fs_info, folio, start, len);
 			btrfs_mark_ordered_io_finished(inode, start, len, false);
 		}
 		return ret;

-- 
2.55.0