Commit 0a0af28c authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Dave Chinner
Browse files

xfs: add xfs_trim_extent 



This helpers allows to trim an extent to a subset of it's original range
while making sure the block numbers in it remain valid,

In the future xfs_trim_extent and xfs_bmapi_trim_map should probably be
merged in some form.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
[hch: split from a previous patch from Darrick, moved around and added
 support for "raw" delayed extents"]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent d33fd776

fs/xfs/libxfs/xfs_bmap.c

+33 −0
Original line number Diff line number Diff line
@@ -3996,6 +3996,39 @@ xfs_bmap_alloc( 
	return xfs_bmap_btalloc(ap);

}



/* Trim extent to fit a logical block range. */

void

xfs_trim_extent(

	struct xfs_bmbt_irec	*irec,

	xfs_fileoff_t		bno,

	xfs_filblks_t		len)

{

	xfs_fileoff_t		distance;

	xfs_fileoff_t		end = bno + len;



	if (irec->br_startoff + irec->br_blockcount <= bno ||

	    irec->br_startoff >= end) {

		irec->br_blockcount = 0;

		return;

	}



	if (irec->br_startoff < bno) {

		distance = bno - irec->br_startoff;

		if (isnullstartblock(irec->br_startblock))

			irec->br_startblock = DELAYSTARTBLOCK;

		if (irec->br_startblock != DELAYSTARTBLOCK &&

		    irec->br_startblock != HOLESTARTBLOCK)

			irec->br_startblock += distance;

		irec->br_startoff += distance;

		irec->br_blockcount -= distance;

	}



	if (end < irec->br_startoff + irec->br_blockcount) {

		distance = irec->br_startoff + irec->br_blockcount - end;

		irec->br_blockcount -= distance;

	}

}



/*

 * Trim the returned map to the required bounds

 */

fs/xfs/libxfs/xfs_bmap.h

+2 −0
Original line number Diff line number Diff line
@@ -190,6 +190,8 @@ void xfs_bmap_trace_exlist(struct xfs_inode *ip, xfs_extnum_t cnt, 
#define	XFS_BMAP_TRACE_EXLIST(ip,c,w)

#endif



void	xfs_trim_extent(struct xfs_bmbt_irec *irec, xfs_fileoff_t bno,

		xfs_filblks_t len);

int	xfs_bmap_add_attrfork(struct xfs_inode *ip, int size, int rsvd);

void	xfs_bmap_local_to_extents_empty(struct xfs_inode *ip, int whichfork);

void	xfs_bmap_add_free(struct xfs_mount *mp, struct xfs_defer_ops *dfops,

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