linux-kernel - Re: [PATCH] ocfs2: fix unexpected zeroing of virtual disk

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Message-ID: <432954d5-3b8e-42f7-8c06-1a489281129e@suse.com>
Date: Sun, 18 Aug 2024 18:31:27 +0800
From: Heming Zhao <heming.zhao@...e.com>
To: Chi Zhiling <chizhiling@....com>, mark@...heh.com, jlbec@...lplan.org,
 joseph.qi@...ux.alibaba.com
Cc: ocfs2-devel@...ts.linux.dev, linux-kernel@...r.kernel.org,
 starzhangzsd@...il.com, Chi Zhiling <chizhiling@...inos.cn>,
 Shida Zhang <zhangshida@...inos.cn>
Subject: Re: [PATCH] ocfs2: fix unexpected zeroing of virtual disk

On 8/15/24 17:21, Chi Zhiling wrote:
> From: Chi Zhiling <chizhiling@...inos.cn>
> 
> In a guest virtual machine, we found that there is unexpected data
> zeroing problem detected occassionly:
> 
> XFS (vdb): Mounting V5 Filesystem
> XFS (vdb): Ending clean mount
> XFS (vdb): Metadata CRC error detected at xfs_refcountbt_read_verify+0x2c/0xf0, xfs_refcountbt block 0x200028
> XFS (vdb): Unmount and run xfs_repair
> XFS (vdb): First 128 bytes of corrupted metadata buffer:
> 00000000e0cd2f5e: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> 00000000cafd57f5: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> 00000000d0298d7d: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> 00000000f0698484: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> 00000000adb789a7: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> 000000005292b878: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> 00000000885b4700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> 00000000fd4b4df7: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> XFS (vdb): metadata I/O error in "xfs_trans_read_buf_map" at daddr 0x200028 len 8 error 74
> XFS (vdb): Error -117 recovering leftover CoW allocations.
> XFS (vdb): xfs_do_force_shutdown(0x8) called from line 994 of file fs/xfs/xfs_mount.c.  Return address = 000000003a53523a
> XFS (vdb): Corruption of in-memory data detected.  Shutting down filesystem
> XFS (vdb): Please umount the filesystem and rectify the problem(s)
> 
> It turns out that the root cause is from the physical host machine.
> More specifically, it is caused by the ocfs2.
> 
> when the page_size is 64k, the block should advance by 16 each time
> instead of 1.
> This will lead to a wrong mapping from the page to the disk, which
> will zero some adjacent part of the disk.
> 
> Suggested-by: Shida Zhang <zhangshida@...inos.cn>
> Signed-off-by: Chi Zhiling <chizhiling@...inos.cn>
> ---
>   fs/ocfs2/aops.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index d6c985cc6353..1fea43c33b6b 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -1187,7 +1187,7 @@ static int ocfs2_write_cluster(struct address_space *mapping,
>   
>   		/* This is the direct io target page. */
>   		if (wc->w_pages[i] == NULL) {
> -			p_blkno++;
> +			p_blkno += (1 << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits));
>   			continue;
>   		}
>   

Looks good to me.
Signed-off-by: Heming Zhao <heming.zhao@...e.com>