linux-kernel - Re: [PATCH v2] f2fs: fix to avoid touching checkpointed data in get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 26 Mar 2021 15:33:22 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH v2] f2fs: fix to avoid touching checkpointed data in
 get_victim()

On 2021/3/25 7:49, Jaegeuk Kim wrote:
> On 03/24, Chao Yu wrote:
>> In CP disabling mode, there are two issues when using LFS or SSR | AT_SSR
>> mode to select victim:
>>
>> 1. LFS is set to find source section during GC, the victim should have
>> no checkpointed data, since after GC, section could not be set free for
>> reuse.
>>
>> Previously, we only check valid chpt blocks in current segment rather
>> than section, fix it.
>>
>> 2. SSR | AT_SSR are set to find target segment for writes which can be
>> fully filled by checkpointed and newly written blocks, we should never
>> select such segment, otherwise it can cause panic or data corruption
>> during allocation, potential case is described as below:
>>
>>   a) target segment has 128 ckpt valid blocks
>>   b) GC migrates 'n' (n < 512) valid blocks to other segment (segment is
>>      still in dirty list)

I missed to change 128 to n, so comments should be updated as below:

   a) target segment has 'n' (n < 512) ckpt valid blocks
   b) GC migrates 'n' valid blocks to other segment (segment is still
      in dirty list)

Thanks,

>>   c) GC migrates '512 - n' blocks to target segment (segment has 'n'
>>      cp_vblocks and '512 - n' vblocks)
>>   d) If GC selects target segment via {AT,}SSR allocator, however there
>>      is no free space in targe segment.