Re: [PATCH v3 3/9] ext4: check return value of ext4_get_block() in ext4_load_tail_bh()

[Jan Kara]

On Wed 08-07-26 14:20:43, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@xxxxxxxxxx>
> 
> ext4_load_tail_bh() ignores the return value of ext4_get_block(), so an
> I/O or allocation failure is silently discarded. buffer_mapped(bh) stays
> false and the function returns NULL, which callers such as
> ext4_block_do_zero_range() treat as "nothing to do" and return success.
> This can mask real failures during zero-range, truncate, or punch-hole
> operations, potentially exposing stale data if the block was not
> actually a hole and needed zeroing. So propagate the error to the
> callers.
> 
> Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/ext4/inode.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index a3f7c71b701d..ba4fc3c93bb6 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4064,7 +4064,9 @@ static struct buffer_head *ext4_load_tail_bh(struct inode *inode, loff_t from)
>  	}
>  	if (!buffer_mapped(bh)) {
>  		BUFFER_TRACE(bh, "unmapped");
> -		ext4_get_block(inode, iblock, bh, 0);
> +		err = ext4_get_block(inode, iblock, bh, 0);
> +		if (err < 0)
> +			goto unlock;
>  		/* unmapped? It's a hole - nothing to do */
>  		if (!buffer_mapped(bh)) {
>  			BUFFER_TRACE(bh, "still unmapped");
> -- 
> 2.52.0
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR