linux-ext4 - Re: [PATCH] ext4: add error handling when discarding is fail in FITRIM ioctl

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Date:	Tue, 24 Jan 2012 15:13:32 +0100
From:	Jan Kara <jack@...e.cz>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	tytso@....edu, adilger.kernel@...ger.ca,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
	Amit Sahrawat <amit.sahrawat83@...il.com>
Subject: Re: [PATCH] ext4: add error handling when discarding is fail in
 FITRIM ioctl

On Sat 21-01-12 02:56:12, Namjae Jeon wrote:
> Although free extents is proper not trimmed(mmc driver return error code while sending trim command), currently FITRIM ioctl return success.
> I tried to add exception routine to inform user error code.
> 
> #> ./fitrim_test 
> end_request: I/O error, dev mmcblk0, sector 27232
> EXT4-fs warning (device mmcblk0): ext4_trim_all_free:4857: Discard command returned error -5
> #>
> 
> Signed-off-by: Namjae Jeon <linkinjeon@...il.com>
> Signed-off-by: Amit Sahrawat <amit.sahrawat83@...il.com>
> ---
>  fs/ext4/mballoc.c |   22 +++++++++++++++-------
>  1 files changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index cb990b2..09cc09a 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -4901,10 +4901,11 @@ error_return:
>   * one will allocate those blocks, mark it as used in buddy bitmap. This must
>   * be called with under the group lock.
>   */
> -static void ext4_trim_extent(struct super_block *sb, int start, int count,
> +static int ext4_trim_extent(struct super_block *sb, int start, int count,
>  			     ext4_group_t group, struct ext4_buddy *e4b)
>  {
>  	struct ext4_free_extent ex;
> +	int err;
>  
>  	trace_ext4_trim_extent(sb, group, start, count);
>  
> @@ -4920,9 +4921,10 @@ static void ext4_trim_extent(struct super_block *sb, int start, int count,
>  	 */
>  	mb_mark_used(e4b, &ex);
>  	ext4_unlock_group(sb, group);
> -	ext4_issue_discard(sb, group, start, count);
> +	err = ext4_issue_discard(sb, group, start, count);
>  	ext4_lock_group(sb, group);
>  	mb_free_blocks(NULL, e4b, start, ex.fe_len);
> +	return err;
>  }
>  
>  /**
> @@ -4978,15 +4980,21 @@ ext4_trim_all_free(struct super_block *sb, ext4_group_t group,
>  		next = mb_find_next_bit(bitmap, max, start);
>  
>  		if ((next - start) >= minblocks) {
> -			ext4_trim_extent(sb, start,
> -					 next - start, group, &e4b);
> -			count += next - start;
> +			ret = ext4_trim_extent(sb, start,
> +						next - start, group, &e4b);
> +			if (ret < 0) {
> +				if (ret != -EOPNOTSUPP)
> +					ext4_warning(sb, "Discard command "
> +						 "returned error %d\n", ret);
> +				break;
> +			} else
> +				count += next - start;
>  		}
>  		free_count += next - start;
>  		start = next + 1;
>  
>  		if (fatal_signal_pending(current)) {
> -			count = -ERESTARTSYS;
> +			ret = -ERESTARTSYS;
>  			break;
>  		}
>  
> @@ -5009,7 +5017,7 @@ out:
>  	ext4_debug("trimmed %d blocks in the group %d\n",
>  		count, group);
>  
> -	return count;
> +	return (ret < 0) ? ret : count;
  I think you need to initialize ret to 0 at the beginning of the function.
Otherwise you could use it uninitialized. Otherwise the patch looks good to
me and makes things consistent with ext3 so after fixing that bug you can add:
  Reviewed-by: Jan Kara <jack@...e.cz>

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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