Re: [PATCH 05/11] xfs: track CoW blocks separately in the inode

[Brian Foster <bfoster@redhat.com>]

On Tue, Jan 23, 2018 at 06:18:29PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Track the number of blocks reserved in the CoW fork so that we can
> move the quota reservations whenever we chown, and don't account for
> CoW fork delalloc reservations in i_delayed_blks.  This should make
> chown work properly for quota reservations, enables us to fully
> account for real extents in the cow fork in the file stat info, and
> improves the post-eof scanning decisions because we're no longer
> confusing data fork delalloc extents with cow fork delalloc extents.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_bmap.c      |   16 ++++++++++++----
>  fs/xfs/libxfs/xfs_inode_buf.c |    1 +
>  fs/xfs/xfs_bmap_util.c        |    5 +++++
>  fs/xfs/xfs_icache.c           |    3 ++-
>  fs/xfs/xfs_inode.c            |   11 +++++------
>  fs/xfs/xfs_inode.h            |    1 +
>  fs/xfs/xfs_iops.c             |    3 ++-
>  fs/xfs/xfs_itable.c           |    3 ++-
>  fs/xfs/xfs_qm.c               |    2 +-
>  fs/xfs/xfs_reflink.c          |    4 ++--
>  fs/xfs/xfs_super.c            |    1 +
>  11 files changed, 34 insertions(+), 16 deletions(-)
> 
> 
...
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 4a38cfc..a208825 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
...
> @@ -1669,7 +1667,7 @@ xfs_release(
>  		truncated = xfs_iflags_test_and_clear(ip, XFS_ITRUNCATED);
>  		if (truncated) {
>  			xfs_iflags_clear(ip, XFS_IDIRTY_RELEASE);
> -			if (ip->i_delayed_blks > 0) {
> +			if (ip->i_delayed_blks > 0 || ip->i_cow_blocks > 0) {
>  				error = filemap_flush(VFS_I(ip)->i_mapping);
>  				if (error)
>  					return error;

Is having cowblocks really relevant to this hunk? I thought this was
purely a delalloc vs. file size thing, but I could be wrong. 

Brian

> @@ -1909,7 +1907,8 @@ xfs_inactive(
>  
>  	if (S_ISREG(VFS_I(ip)->i_mode) &&
>  	    (ip->i_d.di_size != 0 || XFS_ISIZE(ip) != 0 ||
> -	     ip->i_d.di_nextents > 0 || ip->i_delayed_blks > 0))
> +	     ip->i_d.di_nextents > 0 || ip->i_delayed_blks > 0 ||
> +	     ip->i_cow_blocks > 0))
>  		truncate = 1;
>  
>  	error = xfs_qm_dqattach(ip, 0);
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index ff56486..6feee8a 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -62,6 +62,7 @@ typedef struct xfs_inode {
>  	/* Miscellaneous state. */
>  	unsigned long		i_flags;	/* see defined flags below */
>  	unsigned int		i_delayed_blks;	/* count of delay alloc blks */
> +	unsigned int		i_cow_blocks;	/* count of cow fork blocks */
>  
>  	struct xfs_icdinode	i_d;		/* most of ondisk inode */
>  
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 56475fc..6c3381c 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -513,7 +513,8 @@ xfs_vn_getattr(
>  	stat->mtime = inode->i_mtime;
>  	stat->ctime = inode->i_ctime;
>  	stat->blocks =
> -		XFS_FSB_TO_BB(mp, ip->i_d.di_nblocks + ip->i_delayed_blks);
> +		XFS_FSB_TO_BB(mp, ip->i_d.di_nblocks + ip->i_delayed_blks +
> +				  ip->i_cow_blocks);
>  
>  	if (ip->i_d.di_version == 3) {
>  		if (request_mask & STATX_BTIME) {
> diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
> index d583105..412d7eb 100644
> --- a/fs/xfs/xfs_itable.c
> +++ b/fs/xfs/xfs_itable.c
> @@ -122,7 +122,8 @@ xfs_bulkstat_one_int(
>  	case XFS_DINODE_FMT_BTREE:
>  		buf->bs_rdev = 0;
>  		buf->bs_blksize = mp->m_sb.sb_blocksize;
> -		buf->bs_blocks = dic->di_nblocks + ip->i_delayed_blks;
> +		buf->bs_blocks = dic->di_nblocks + ip->i_delayed_blks +
> +				 ip->i_cow_blocks;
>  		break;
>  	}
>  	xfs_iunlock(ip, XFS_ILOCK_SHARED);
> diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
> index 5b848f4..28f12f8 100644
> --- a/fs/xfs/xfs_qm.c
> +++ b/fs/xfs/xfs_qm.c
> @@ -1847,7 +1847,7 @@ xfs_qm_vop_chown_reserve(
>  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
>  	ASSERT(XFS_IS_QUOTA_RUNNING(mp));
>  
> -	delblks = ip->i_delayed_blks;
> +	delblks = ip->i_delayed_blks + ip->i_cow_blocks;
>  	blkflags = XFS_IS_REALTIME_INODE(ip) ?
>  			XFS_QMOPT_RES_RTBLKS : XFS_QMOPT_RES_REGBLKS;
>  
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index e367351..f875ea7 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -619,7 +619,7 @@ xfs_reflink_cancel_cow_blocks(
>  	}
>  
>  	/* clear tag if cow fork is emptied */
> -	if (!ifp->if_bytes)
> +	if (ip->i_cow_blocks == 0)
>  		xfs_inode_clear_cowblocks_tag(ip);
>  
>  	return error;
> @@ -704,7 +704,7 @@ xfs_reflink_end_cow(
>  	trace_xfs_reflink_end_cow(ip, offset, count);
>  
>  	/* No COW extents?  That's easy! */
> -	if (ifp->if_bytes == 0)
> +	if (ip->i_cow_blocks == 0)
>  		return 0;
>  
>  	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index f3e0001..9d04cfb 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -989,6 +989,7 @@ xfs_fs_destroy_inode(
>  	xfs_inactive(ip);
>  
>  	ASSERT(XFS_FORCED_SHUTDOWN(ip->i_mount) || ip->i_delayed_blks == 0);
> +	ASSERT(XFS_FORCED_SHUTDOWN(ip->i_mount) || ip->i_cow_blocks == 0);
>  	XFS_STATS_INC(ip->i_mount, vn_reclaim);
>  
>  	/*
> 
> --
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