linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: fix wrong block mapping for multi-devices

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Message-ID: <fdfe10ef-7122-4d84-9299-e16294a1e2d5@kernel.org>
Date: Thu, 9 Oct 2025 11:53:28 +0800
From: Chao Yu <chao@...nel.org>
To: Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
 linux-f2fs-devel@...ts.sourceforge.net
Cc: chao@...nel.org, stable@...r.kernel.org
Subject: Re: [f2fs-dev] [PATCH] f2fs: fix wrong block mapping for
 multi-devices

On 10/7/2025 11:53 AM, Jaegeuk Kim via Linux-f2fs-devel wrote:
> Assuming the disk layout as below,
> 
> disk0: 0            --- 0x00035abfff
> disk1: 0x00035ac000 --- 0x00037abfff
> disk2: 0x00037ac000 --- 0x00037ebfff
> 
> and we want to read data from offset=13568 having len=128 across the block
> devices, we can illustrate the block addresses like below.
> 
> 0 .. 0x00037ac000 ------------------- 0x00037ebfff, 0x00037ec000 -------
>            |          ^            ^                                ^
>            |   fofs   0            13568                            13568+128
>            |       ------------------------------------------------------
>            |   LBA    0x37e8aa9    0x37ebfa9                        0x37ec029
>            --- map    0x3caa9      0x3ffa9
> 
> In this example, we should give the relative map of the target block device
> ranging from 0x3caa9 to 0x3ffa9 where the length should be calculated by
> 0x37ebfff + 1 - 0x37ebfa9.
> 
> In the below equation, however, map->m_pblk was supposed to be the original
> address instead of the one from the target block address.
> 
>   - map->m_len = min(map->m_len, dev->end_blk + 1 - map->m_pblk);
> 
> Cc: stable@...r.kernel.org
> Fixes: 71f2c8206202 ("f2fs: multidevice: support direct IO")
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>

Looks good to me, thanks for the fix!

Reviewed-by: Chao Yu <chao@...nel.org>

Thanks,