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

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Date:	Thu, 9 Feb 2012 13:26:11 +0900
From:	Namjae Jeon <linkinjeon@...il.com>
To:	tytso@....edu
Cc:	adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: Re: [PATCH] ext4: add error handling when discarding is fail in
 FITRIM ioctl

Hi. Ted.

Would you check this patch ? maybe, this patch was posted during your vacation.

Thanks.

2012/1/25 Namjae Jeon <linkinjeon@...il.com>:
> 2012/1/24 Jan Kara <jack@...e.cz>:
>> 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>
> Hi. Jan.
> Thanks for your review.~
>>
>>                                                                Honza
>> --
>> Jan Kara <jack@...e.cz>
>> SUSE Labs, CR
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