linux-ext4 - Re: [PATCH] ext4: clear EXT4_GROUP_INFO_WAS_TRIMMED

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Date: Mon, 6 May 2024 08:59:17 +0800
From: yangerkun <yangerkun@...weicloud.com>
To: yangerkun <yangerkun@...wei.com>, Jan Kara <jack@...e.cz>,
 "Theodore Y . Ts'o" <tytso@....edu>
Cc: adilger.kernel@...ger.ca, boyu.mt@...bao.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: clear EXT4_GROUP_INFO_WAS_TRIMMED_BIT even mount
 with discard

Hi, Ted,

Ping again...

在 2024/3/30 16:04, yangerkun 写道:
> Hi, Ted,
> 
> Ping for this patch.
> 
> 
> 在 2024/2/21 19:18, Jan Kara 写道:
>> On Sat 30-12-23 15:06:54, yangerkun wrote:
>>> Commit 3d56b8d2c74c ("ext4: Speed up FITRIM by recording flags in
>>> ext4_group_info") speed up fstrim by skipping trim trimmed group. We
>>> also has the chance to clear trimmed once there exists some block free
>>> for this group(mount without discard), and the next trim for this group
>>> will work well too.
>>>
>>> For mount with discard, we will issue dicard when we free blocks, so
>>> leave trimmed flag keep alive to skip useless trim trigger from
>>> userspace seems reasonable. But for some case like ext4 build on
>>> dm-thinpool(ext4 blocksize 4K, pool blocksize 128K), discard from ext4
>>> maybe unaligned for dm thinpool, and thinpool will just finish this
>>> discard(see process_discard_bio when begein equals to end) without
>>> actually process discard. For this case, trim from userspace can really
>>> help us to free some thinpool block.
>>>
>>> So convert to clear trimmed flag for all case no matter mounted with
>>> discard or not.
>>>
>>> Fixes: 3d56b8d2c74c ("ext4: Speed up FITRIM by recording flags in 
>>> ext4_group_info")
>>> Signed-off-by: yangerkun <yangerkun@...weicloud.com>
>>
>> Thanks for the fix. It looks good. Feel free to add:
>>
>> Reviewed-by: Jan Kara <jack@...e.cz>
>>
>>                                 Honza
>>
>>> ---
>>>   fs/ext4/mballoc.c | 10 ++++------
>>>   1 file changed, 4 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
>>> index d72b5e3c92ec..69240ae775f1 100644
>>> --- a/fs/ext4/mballoc.c
>>> +++ b/fs/ext4/mballoc.c
>>> @@ -3855,11 +3855,8 @@ static void ext4_free_data_in_buddy(struct 
>>> super_block *sb,
>>>       /*
>>>        * Clear the trimmed flag for the group so that the next
>>>        * ext4_trim_fs can trim it.
>>> -     * If the volume is mounted with -o discard, online discard
>>> -     * is supported and the free blocks will be trimmed online.
>>>        */
>>> -    if (!test_opt(sb, DISCARD))
>>> -        EXT4_MB_GRP_CLEAR_TRIMMED(db);
>>> +    EXT4_MB_GRP_CLEAR_TRIMMED(db);
>>>       if (!db->bb_free_root.rb_node) {
>>>           /* No more items in the per group rb tree
>>> @@ -6481,8 +6478,9 @@ static void ext4_mb_clear_bb(handle_t *handle, 
>>> struct inode *inode,
>>>                        " group:%u block:%d count:%lu failed"
>>>                        " with %d", block_group, bit, count,
>>>                        err);
>>> -        } else
>>> -            EXT4_MB_GRP_CLEAR_TRIMMED(e4b.bd_info);
>>> +        }
>>> +
>>> +        EXT4_MB_GRP_CLEAR_TRIMMED(e4b.bd_info);
>>>           ext4_lock_group(sb, block_group);
>>>           mb_free_blocks(inode, &e4b, bit, count_clusters);
>>> -- 
>>> 2.39.2
>>>
>>>