Re: [PATCH 10/20] xfs: remove xfs_reflink_dirty_extents

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, Oct 08, 2019 at 09:15:17AM +0200, Christoph Hellwig wrote:
> Now that xfs_file_unshare is not completely dumb we can just call it
> directly without iterating the extent and reflink btrees ourselves.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/xfs_reflink.c | 103 +++----------------------------------------
>  1 file changed, 5 insertions(+), 98 deletions(-)
> 
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index a9634110c783..7fc728a8852b 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1381,85 +1381,6 @@ xfs_reflink_remap_prep(
>  	return ret;
>  }
>  
> -/*
> - * The user wants to preemptively CoW all shared blocks in this file,
> - * which enables us to turn off the reflink flag.  Iterate all
> - * extents which are not prealloc/delalloc to see which ranges are
> - * mentioned in the refcount tree, then read those blocks into the
> - * pagecache, dirty them, fsync them back out, and then we can update
> - * the inode flag.  What happens if we run out of memory? :)
> - */
> -STATIC int
> -xfs_reflink_dirty_extents(
> -	struct xfs_inode	*ip,
> -	xfs_fileoff_t		fbno,
> -	xfs_filblks_t		end,
> -	xfs_off_t		isize)
> -{
> -	struct xfs_mount	*mp = ip->i_mount;
> -	xfs_agnumber_t		agno;
> -	xfs_agblock_t		agbno;
> -	xfs_extlen_t		aglen;
> -	xfs_agblock_t		rbno;
> -	xfs_extlen_t		rlen;
> -	xfs_off_t		fpos;
> -	xfs_off_t		flen;
> -	struct xfs_bmbt_irec	map[2];
> -	int			nmaps;
> -	int			error = 0;
> -
> -	while (end - fbno > 0) {
> -		nmaps = 1;
> -		/*
> -		 * Look for extents in the file.  Skip holes, delalloc, or
> -		 * unwritten extents; they can't be reflinked.
> -		 */
> -		error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
> -		if (error)
> -			goto out;
> -		if (nmaps == 0)
> -			break;
> -		if (!xfs_bmap_is_real_extent(&map[0]))
> -			goto next;
> -
> -		map[1] = map[0];
> -		while (map[1].br_blockcount) {
> -			agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
> -			agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
> -			aglen = map[1].br_blockcount;
> -
> -			error = xfs_reflink_find_shared(mp, NULL, agno, agbno,
> -					aglen, &rbno, &rlen, true);
> -			if (error)
> -				goto out;
> -			if (rbno == NULLAGBLOCK)
> -				break;
> -
> -			/* Dirty the pages */
> -			xfs_iunlock(ip, XFS_ILOCK_EXCL);
> -			fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +
> -					(rbno - agbno));
> -			flen = XFS_FSB_TO_B(mp, rlen);
> -			if (fpos + flen > isize)
> -				flen = isize - fpos;
> -			error = iomap_file_unshare(VFS_I(ip), fpos, flen,
> -					&xfs_iomap_ops);
> -			xfs_ilock(ip, XFS_ILOCK_EXCL);
> -			if (error)
> -				goto out;
> -
> -			map[1].br_blockcount -= (rbno - agbno + rlen);
> -			map[1].br_startoff += (rbno - agbno + rlen);
> -			map[1].br_startblock += (rbno - agbno + rlen);
> -		}
> -
> -next:
> -		fbno = map[0].br_startoff + map[0].br_blockcount;
> -	}
> -out:
> -	return error;
> -}
> -
>  /* Does this inode need the reflink flag? */
>  int
>  xfs_reflink_inode_has_shared_extents(
> @@ -1596,10 +1517,7 @@ xfs_reflink_unshare(
>  	xfs_off_t		offset,
>  	xfs_off_t		len)
>  {
> -	struct xfs_mount	*mp = ip->i_mount;
> -	xfs_fileoff_t		fbno;
> -	xfs_filblks_t		end;
> -	xfs_off_t		isize;
> +	struct inode		*inode = VFS_I(ip);
>  	int			error;
>  
>  	if (!xfs_is_reflink_inode(ip))
> @@ -1607,20 +1525,12 @@ xfs_reflink_unshare(
>  
>  	trace_xfs_reflink_unshare(ip, offset, len);
>  
> -	inode_dio_wait(VFS_I(ip));
> +	inode_dio_wait(inode);
>  
> -	/* Try to CoW the selected ranges */
> -	xfs_ilock(ip, XFS_ILOCK_EXCL);
> -	fbno = XFS_B_TO_FSBT(mp, offset);
> -	isize = i_size_read(VFS_I(ip));
> -	end = XFS_B_TO_FSB(mp, offset + len);
> -	error = xfs_reflink_dirty_extents(ip, fbno, end, isize);
> +	error = iomap_file_unshare(inode, offset, len, &xfs_iomap_ops);
>  	if (error)
> -		goto out_unlock;
> -	xfs_iunlock(ip, XFS_ILOCK_EXCL);
> -
> -	/* Wait for the IO to finish */
> -	error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
> +		goto out;
> +	error = filemap_write_and_wait(inode->i_mapping);
>  	if (error)
>  		goto out;
>  
> @@ -1628,11 +1538,8 @@ xfs_reflink_unshare(
>  	error = xfs_reflink_try_clear_inode_flag(ip);
>  	if (error)
>  		goto out;
> -
>  	return 0;
>  
> -out_unlock:
> -	xfs_iunlock(ip, XFS_ILOCK_EXCL);
>  out:
>  	trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
>  	return error;
> -- 
> 2.20.1
>