[PATCH 5.15.y] ext4: propagate errors from fast commit range replay

[Sasha Levin <sashal@kernel.org>]

From: Guanghui Yang <3497809730@qq.com>

[ Upstream commit d8b8dd3530bf41e14b118702cdaf9de64bb96885 ]

ext4_fc_replay() stops replaying fast commit tags only when a tag
handler returns a negative error. However, ext4_fc_replay_add_range()
and ext4_fc_replay_del_range() currently return 0 from their common
exit paths even after internal failures.

This hides errors from ext4_fc_record_modified_inode(),
ext4_map_blocks(), ext4_find_extent(), ext4_ext_insert_extent(),
ext4_ext_replay_update_ex(), and ext4_ext_remove_space(). As a result,
a failed ADD_RANGE or DEL_RANGE replay can be treated as successful and
the replay code may continue with subsequent fast commit tags.

This is particularly problematic for DEL_RANGE because it may already
have marked blocks as free before ext4_ext_remove_space() fails. If the
error is swallowed, replay may continue from a partially applied range
operation.

Return the saved error from the common exit paths and make the
ERR_PTR() cases in ADD_RANGE store PTR_ERR() before jumping to out.

Fixes: 8016e29f4362 ("ext4: fast commit recovery path")
Cc: stable@vger.kernel.org
Signed-off-by: Guanghui Yang <3497809730@qq.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/tencent_E3622146846A84C75C31C7D32AC4D5AD0605@qq.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[ kept the existing `ext4_find_extent(inode, cur, NULL, 0)` call and dropped the `ext4_ext_insert_extent()` error-capture hunk, since this tree's extents API predates the ppath rework and already returns errors via `int` ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ext4/fast_commit.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index b0c7d8e28337e..84b219cde46c8 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -1780,8 +1780,10 @@ static int ext4_fc_replay_add_range(struct super_block *sb,
 		if (ret == 0) {
 			/* Range is not mapped */
 			path = ext4_find_extent(inode, cur, NULL, 0);
-			if (IS_ERR(path))
+			if (IS_ERR(path)) {
+				ret = PTR_ERR(path);
 				goto out;
+			}
 			memset(&newex, 0, sizeof(newex));
 			newex.ee_block = cpu_to_le32(cur);
 			ext4_ext_store_pblock(
@@ -1843,9 +1845,10 @@ static int ext4_fc_replay_add_range(struct super_block *sb,
 	}
 	ext4_ext_replay_shrink_inode(inode, i_size_read(inode) >>
 					sb->s_blocksize_bits);
+	ret = 0;
 out:
 	iput(inode);
-	return 0;
+	return ret;
 }
 
 /* Replay DEL_RANGE tag */
@@ -1906,9 +1909,10 @@ ext4_fc_replay_del_range(struct super_block *sb,
 	ext4_ext_replay_shrink_inode(inode,
 		i_size_read(inode) >> sb->s_blocksize_bits);
 	ext4_mark_inode_dirty(NULL, inode);
+	ret = 0;
 out:
 	iput(inode);
-	return 0;
+	return ret;
 }
 
 static void ext4_fc_set_bitmaps_and_counters(struct super_block *sb)
-- 
2.53.0