linux-kernel - Re: [PATCH] f2fs: fix 0 addr of multi devices when dio mapping

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Message-ID: <9172f17e-deb4-4219-b917-330cdffa5a81@kernel.org>
Date: Fri, 29 Mar 2024 18:27:22 +0800
From: Chao Yu <chao@...nel.org>
To: Wu Bo <bo.wu@...o.com>, Jaegeuk Kim <jaegeuk@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
 Wu Bo <wubo.oduw@...il.com>
Subject: Re: [PATCH] f2fs: fix 0 addr of multi devices when dio mapping

On 2024/3/29 14:55, Wu Bo wrote:
> Consider of a f2fs system with 2 devices:
> Info: Device[0] : /dev/block/dm-46 blkaddr = 0--3fffff
> Info: Device[1] : /dev/block/dm-47 blkaddr = 400000--67fffff
> 
> f2fs_map_blocks will return logical addr of fs when doing buffered io:
> f2fs_map_blocks: dev = (254,46), ino = 40020, file offset = 462865, start blkaddr = 0x400000
> 
> While dio mapping will return the addr of device:
> f2fs_map_blocks: dev = (254,47), ino = 40020, file offset = 462865, start blkaddr = 0x0
> 
> So the addr=0 is valid when the map.m_bdev is not s_bdev.

Thanks for catching this, there is already a formal patch as below link:

https://lore.kernel.org/linux-f2fs-devel/20240327074223.2216487-1-chao@kernel.org

Thanks,

> 
> Fixes: 8d3c1fa3fa5e ("f2fs: don't rely on F2FS_MAP_* in f2fs_iomap_begin")
> Signed-off-by: Wu Bo <bo.wu@...o.com>
> ---
>   fs/f2fs/data.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index d9494b5fc7c1..dca3628932c7 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -4185,7 +4185,8 @@ static int f2fs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>   	if (WARN_ON_ONCE(map.m_pblk == COMPRESS_ADDR))
>   		return -EINVAL;
>   
> -	if (map.m_pblk != NULL_ADDR) {
> +	if (map.m_pblk != NULL_ADDR ||
> +		(map.m_multidev_dio && map.m_bdev != inode->i_sb->s_bdev)) {
>   		iomap->length = blks_to_bytes(inode, map.m_len);
>   		iomap->type = IOMAP_MAPPED;
>   		iomap->flags |= IOMAP_F_MERGED;