linux-kernel - Re: [PATCH] f2fs: avoid GC causing encrypted file corrupted

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Message-ID: <19e63fa7-1a48-c1de-eef5-cde242e8300d@kernel.org>
Date:   Tue, 18 Sep 2018 21:21:49 +0800
From:   Chao Yu <chao@...nel.org>
To:     Yunlong Song <yunlong.song@...wei.com>, jaegeuk@...nel.org,
        yuchao0@...wei.com, yunlong.song@...oud.com
Cc:     miaoxie@...wei.com, bintian.wang@...wei.com, shengyong1@...wei.com,
        heyunlei@...wei.com, linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: avoid GC causing encrypted file corrupted

On 2018/9/18 20:39, Yunlong Song wrote:
> The encrypted file may be corrupted by GC in following case:
> 
> Time 1: | segment 1 blkaddr = A |  GC -> | segment 2 blkaddr = B |
> Encrypted block 1 is moved from blkaddr A of segment 1 to blkaddr B of
> segment 2,
> 
> Time 2: | segment 1 blkaddr = B |  GC -> | segment 3 blkaddr = C |
> 
> Before page 1 is written back and if segment 2 become a victim, then
> page 1 is moved from blkaddr B of segment 2 to blkaddr Cof segment 3,
> during the GC process of Time 2, f2fs should wait for page 1 written back
> before reading it, or move_data_block will read a garbage block from
> blkaddr B since page is not written back to blkaddr B yet.
> 
> Commit 6aa58d8a ("f2fs: readahead encrypted block during GC") introduce
> ra_data_block to read encrypted block, but it forgets to add
> f2fs_wait_on_page_writeback to avoid racing between GC and flush.
> 
> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>

Reviewed-by: Chao Yu <yuchao0@...wei.com>

Thanks,