ext4: Make sure BH_New bit is cleared in ->write_end handler

Currently we clear BH_New bit in case of error and also in the standard
ext4_write_end() handler (in block_commit_write()). However
ext4_journalled_write_end() misses this clearing and thus we are leaving
stale BH_New bits behind. Generally ext4_block_write_begin() clears
these bits before any harm can be done but in case blocksize < pagesize
and we hit some error when processing a page with these stale bits,
we'll try to zero buffers with these stale BH_New bits and jbd2 will
complain (as buffers were not prepared for writing in this transaction).
Fix the problem by clearing BH_New bits in ext4_journalled_write_end()
and WARN if ext4_block_write_begin() sees stale BH_New bits.

Reported-by: Baolin Liu <[email protected]>
Reported-by: Zhi Long <[email protected]>
Fixes: 3910b513fcdf ("ext4: persist the new uptodate buffers in ext4_journalled_zero_new_buffers")
Signed-off-by: Jan Kara <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8bdf2029ebc7..eeccb6f588f9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1189,7 +1189,7 @@ int ext4_block_write_begin(handle_t *handle, struct folio *folio,
 			}
 			continue;
 		}
-		if (buffer_new(bh))
+		if (WARN_ON_ONCE(buffer_new(bh)))
 			clear_buffer_new(bh);
 		if (!buffer_mapped(bh)) {
 			WARN_ON(bh->b_size != blocksize);
@@ -1417,6 +1417,7 @@ static int write_end_fn(handle_t *handle, struct inode *inode,
 	ret = ext4_dirty_journalled_data(handle, bh);
 	clear_buffer_meta(bh);
 	clear_buffer_prio(bh);
+	clear_buffer_new(bh);
 	return ret;
 }