Re: [PATCH v2] ext4: propagate errors from fast commit range replay

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2026/7/12 12:41, Guanghui Yang 写道:
> 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
> Fixes: 57a304cfd43b ("btrfs: do not panic in __add_reloc_root")

WTF? Stop hallucinate, no matter if it's from LLM or yourself.

How could a ext4 commit related to btrfs?

> Signed-off-by: Guanghui Yang <3497809730@qq.com>
> ---
> Changes in v2:
> - Add Fixes tag for the commit that made the duplicate-insert error path reachable.
> 
>   fs/ext4/fast_commit.c | 16 ++++++++++++----
>   1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> index 8e2259799614..fbb486d917b0 100644
> --- a/fs/ext4/fast_commit.c
> +++ b/fs/ext4/fast_commit.c
> @@ -2196,8 +2196,11 @@ static int ext4_fc_replay_add_range(struct super_block *sb, u8 *val)
>   		if (ret == 0) {
>   			/* Range is not mapped */
>   			path = ext4_find_extent(inode, cur, path, 0);
> -			if (IS_ERR(path))
> +			if (IS_ERR(path)) {
> +				ret = PTR_ERR(path);
> +				path = NULL;
>   				goto out;
> +			}
>   			memset(&newex, 0, sizeof(newex));
>   			newex.ee_block = cpu_to_le32(cur);
>   			ext4_ext_store_pblock(
> @@ -2209,8 +2212,11 @@ static int ext4_fc_replay_add_range(struct super_block *sb, u8 *val)
>   			path = ext4_ext_insert_extent(NULL, inode,
>   						      path, &newex, 0);
>   			up_write((&EXT4_I(inode)->i_data_sem));
> -			if (IS_ERR(path))
> +			if (IS_ERR(path)) {
> +				ret = PTR_ERR(path);
> +				path = NULL;
>   				goto out;
> +			}
>   			goto next;
>   		}
>   
> @@ -2257,10 +2263,11 @@ static int ext4_fc_replay_add_range(struct super_block *sb, u8 *val)
>   	}
>   	ext4_ext_replay_shrink_inode(inode, i_size_read(inode) >>
>   					sb->s_blocksize_bits);
> +	ret = 0;
>   out:
>   	ext4_free_ext_path(path);
>   	iput(inode);
> -	return 0;
> +	return ret;
>   }
>   
>   /* Replay DEL_RANGE tag */
> @@ -2320,9 +2327,10 @@ ext4_fc_replay_del_range(struct super_block *sb, u8 *val)
>   	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)