linux-kernel - Re: [f2fs-dev] [PATCH v3 3/6] f2fs: compress: fix to check unreleased compressed cluster

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Date: Thu, 11 Jan 2024 09:33:21 +0800
From: Chao Yu <chao@...nel.org>
To: Daeho Jeong <daeho43@...il.com>
Cc: jaegeuk@...nel.org, linux-kernel@...r.kernel.org,
 linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v3 3/6] f2fs: compress: fix to check unreleased
 compressed cluster

On 2024/1/11 9:18, Daeho Jeong wrote:
> On Thu, Dec 28, 2023 at 6:33 AM Chao Yu <chao@...nel.org> wrote:
>>
>> From: Sheng Yong <shengyong@...o.com>
>>
>> Compressed cluster may not be released due to we can fail in
>> release_compress_blocks(), fix to handle reserved compressed
>> cluster correctly in reserve_compress_blocks().
>>
>> Fixes: 4c8ff7095bef ("f2fs: support data compression")
>> Signed-off-by: Sheng Yong <shengyong@...o.com>
>> Signed-off-by: Chao Yu <chao@...nel.org>
>> ---
>>   fs/f2fs/file.c | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 026d05a7edd8..782ae3be48f6 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -3624,6 +3624,15 @@ static int reserve_compress_blocks(struct dnode_of_data *dn, pgoff_t count)
>>                                  goto next;
>>                          }
>>
>> +                       /*
>> +                        * compressed cluster was not released due to
>> +                        * it fails in release_compress_blocks().
>> +                        */
>> +                       if (blkaddr == NEW_ADDR) {
>> +                               compr_blocks++;
>> +                               continue;
>> +                       }
>> +
>>                          if (__is_valid_data_blkaddr(blkaddr)) {
>>                                  compr_blocks++;
>>                                  continue;
> 
> How about merging two conditions like "blkaddr == NEW_ADDR ||
> __is_valid_data_blkaddr(blkaddr)"?

Oh, sure.

> 
>> @@ -3633,6 +3642,9 @@ static int reserve_compress_blocks(struct dnode_of_data *dn, pgoff_t count)
>>                  }
>>
>>                  reserved = cluster_size - compr_blocks;
>> +               if (!reserved)
>> +                       goto next;
>> +
> 
> How can the reserved variable be zero?

I guess it can happen if a cluster was not released during
release_compress_blocks(), then all blocks in the cluster should
has been reserved, so, in this round of reserving, it needs to skip
reserve blocks, right?

Thanks,

> 
>>                  ret = inc_valid_block_count(sbi, dn->inode, &reserved);
>>                  if (ret)
>>                          return ret;
>> --
>> 2.40.1
>>
>>
>>
>> _______________________________________________
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>> Linux-f2fs-devel@...ts.sourceforge.net
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