[RESEND] ext4: add error handling when discarding is fail in FITRIM ioctl.

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@gmail.com>
Signed-off-by: Amit Sahrawat <amit.sahrawat83@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/mballoc.c |   24 ++++++++++++++++--------
 1 files changed, 16 insertions(+), 8 deletions(-)

Hi Ted,

Can you please update us about the status of this patch? Please let us
know in case there are any suggestions about this.
Looking forward to hear your opinion about the same.

Thanks & Regards,
Amit Sahrawat

On Sun, Mar 4, 2012 at 5:55 PM, Namjae Jeon <linkinjeon@gmail.com> 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@gmail.com>
> Signed-off-by: Amit Sahrawat <amit.sahrawat83@gmail.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> ---
>  fs/ext4/mballoc.c |   24 ++++++++++++++++--------
>  1 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index cb990b2..94182d4 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;
>  }
>
>  /**
> @@ -4951,7 +4953,7 @@ ext4_trim_all_free(struct super_block *sb, ext4_group_t group,
>        void *bitmap;
>        ext4_grpblk_t next, count = 0, free_count = 0;
>        struct ext4_buddy e4b;
> -       int ret;
> +       int ret = 0;
>
>        trace_ext4_trim_all_free(sb, group, start, max);
>
> @@ -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;
>  }
>
>  /**
> --
> 1.7.5.4
>
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