[PATCH] xfs: always swap the cow forks when swapping extents

[PATCH] xfs: always swap the cow forks when swapping extents

[Darrick J. Wong]

Since the CoW fork exists as a secondary data structure to the data
fork, we must always swap cow forks during swapext.  We also need to
swap the extent counts and reset the cowblocks tags.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/xfs_bmap_util.c |   24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index bc6c6e1..e9db7fc 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -2122,11 +2122,31 @@ xfs_swap_extents(
 		ip->i_d.di_flags2 |= tip->i_d.di_flags2 & XFS_DIFLAG2_REFLINK;
 		tip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
 		tip->i_d.di_flags2 |= f & XFS_DIFLAG2_REFLINK;
+	}
+
+	/* Swap the cow forks. */
+	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
+		xfs_extnum_t	extnum;
+
+		ASSERT(ip->i_cformat == XFS_DINODE_FMT_EXTENTS);
+		ASSERT(tip->i_cformat == XFS_DINODE_FMT_EXTENTS);
+
+		extnum = ip->i_cnextents;
+		ip->i_cnextents = tip->i_cnextents;
+		tip->i_cnextents = extnum;
+
 		cowfp = ip->i_cowfp;
 		ip->i_cowfp = tip->i_cowfp;
 		tip->i_cowfp = cowfp;
-		xfs_inode_set_cowblocks_tag(ip);
-		xfs_inode_set_cowblocks_tag(tip);
+
+		if (ip->i_cowfp && ip->i_cnextents)
+			xfs_inode_set_cowblocks_tag(ip);
+		else
+			xfs_inode_clear_cowblocks_tag(ip);
+		if (tip->i_cowfp && tip->i_cnextents)
+			xfs_inode_set_cowblocks_tag(tip);
+		else
+			xfs_inode_clear_cowblocks_tag(tip);
 	}
 
 	xfs_trans_log_inode(tp, ip,  src_log_flags);

Re: [PATCH] xfs: always swap the cow forks when swapping extents

[Brian Foster]

On Sat, Sep 23, 2017 at 12:12:08AM -0700, Darrick J. Wong wrote:
> Since the CoW fork exists as a secondary data structure to the data
> fork, we must always swap cow forks during swapext.  We also need to
> swap the extent counts and reset the cowblocks tags.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/xfs_bmap_util.c |   24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index bc6c6e1..e9db7fc 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -2122,11 +2122,31 @@ xfs_swap_extents(
>  		ip->i_d.di_flags2 |= tip->i_d.di_flags2 & XFS_DIFLAG2_REFLINK;
>  		tip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
>  		tip->i_d.di_flags2 |= f & XFS_DIFLAG2_REFLINK;
> +	}
> +
> +	/* Swap the cow forks. */
> +	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
> +		xfs_extnum_t	extnum;
> +
> +		ASSERT(ip->i_cformat == XFS_DINODE_FMT_EXTENTS);
> +		ASSERT(tip->i_cformat == XFS_DINODE_FMT_EXTENTS);
> +
> +		extnum = ip->i_cnextents;
> +		ip->i_cnextents = tip->i_cnextents;
> +		tip->i_cnextents = extnum;
> +
>  		cowfp = ip->i_cowfp;
>  		ip->i_cowfp = tip->i_cowfp;
>  		tip->i_cowfp = cowfp;
> -		xfs_inode_set_cowblocks_tag(ip);
> -		xfs_inode_set_cowblocks_tag(tip);
> +
> +		if (ip->i_cowfp && ip->i_cnextents)
> +			xfs_inode_set_cowblocks_tag(ip);
> +		else
> +			xfs_inode_clear_cowblocks_tag(ip);
> +		if (tip->i_cowfp && tip->i_cnextents)
> +			xfs_inode_set_cowblocks_tag(tip);
> +		else
> +			xfs_inode_clear_cowblocks_tag(tip);
>  	}
>  
>  	xfs_trans_log_inode(tp, ip,  src_log_flags);
> --
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Re: [PATCH] xfs: always swap the cow forks when swapping extents

[Christoph Hellwig]

On Sat, Sep 23, 2017 at 12:12:08AM -0700, Darrick J. Wong wrote:
> Since the CoW fork exists as a secondary data structure to the data
> fork, we must always swap cow forks during swapext.  We also need to
> swap the extent counts and reset the cowblocks tags.

Do you have a test that triggers a problem without this? :)

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH] xfs: always swap the cow forks when swapping extents

[Darrick J. Wong]

On Tue, Sep 26, 2017 at 07:44:21AM -0700, Christoph Hellwig wrote:
> On Sat, Sep 23, 2017 at 12:12:08AM -0700, Darrick J. Wong wrote:
> > Since the CoW fork exists as a secondary data structure to the data
> > fork, we must always swap cow forks during swapext.  We also need to
> > swap the extent counts and reset the cowblocks tags.
> 
> Do you have a test that triggers a problem without this? :)

Yes, but it doesn't trigger it reliably, so I've not yet sent it.

--D

> 
> Looks good:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> --
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