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Commit 4862cfe8 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: support removing extents from CoW fork 



Create a helper method to remove extents from the CoW fork without
any of the side effects (rmapbt/bmbt updates) of the regular extent
deletion routine.  We'll eventually use this to clear out the CoW fork
during ioend processing.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent ef473667

fs/xfs/libxfs/xfs_bmap.c

+170 −0
Original line number Diff line number Diff line
@@ -4908,6 +4908,7 @@ xfs_bmap_del_extent( 
		/*

		 * Matches the whole extent.  Delete the entry.

		 */

		trace_xfs_bmap_pre_update(ip, *idx, state, _THIS_IP_);

		xfs_iext_remove(ip, *idx, 1,

				whichfork == XFS_ATTR_FORK ? BMAP_ATTRFORK : 0);

		--*idx;
@@ -5124,6 +5125,175 @@ xfs_bmap_del_extent( 
	return error;

}



/* Remove an extent from the CoW fork.  Similar to xfs_bmap_del_extent. */

int

xfs_bunmapi_cow(

	struct xfs_inode		*ip,

	struct xfs_bmbt_irec		*del)

{

	xfs_filblks_t			da_new;

	xfs_filblks_t			da_old;

	xfs_fsblock_t			del_endblock = 0;

	xfs_fileoff_t			del_endoff;

	int				delay;

	struct xfs_bmbt_rec_host	*ep;

	int				error;

	struct xfs_bmbt_irec		got;

	xfs_fileoff_t			got_endoff;

	struct xfs_ifork		*ifp;

	struct xfs_mount		*mp;

	xfs_filblks_t			nblks;

	struct xfs_bmbt_irec		new;

	/* REFERENCED */

	uint				qfield;

	xfs_filblks_t			temp;

	xfs_filblks_t			temp2;

	int				state = BMAP_COWFORK;

	int				eof;

	xfs_extnum_t			eidx;



	mp = ip->i_mount;

	XFS_STATS_INC(mp, xs_del_exlist);



	ep = xfs_bmap_search_extents(ip, del->br_startoff, XFS_COW_FORK, &eof,

			&eidx, &got, &new);



	ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); ifp = ifp;

	ASSERT((eidx >= 0) && (eidx < ifp->if_bytes /

		(uint)sizeof(xfs_bmbt_rec_t)));

	ASSERT(del->br_blockcount > 0);

	ASSERT(got.br_startoff <= del->br_startoff);

	del_endoff = del->br_startoff + del->br_blockcount;

	got_endoff = got.br_startoff + got.br_blockcount;

	ASSERT(got_endoff >= del_endoff);

	delay = isnullstartblock(got.br_startblock);

	ASSERT(isnullstartblock(del->br_startblock) == delay);

	qfield = 0;

	error = 0;

	/*

	 * If deleting a real allocation, must free up the disk space.

	 */

	if (!delay) {

		nblks = del->br_blockcount;

		qfield = XFS_TRANS_DQ_BCOUNT;

		/*

		 * Set up del_endblock and cur for later.

		 */

		del_endblock = del->br_startblock + del->br_blockcount;

		da_old = da_new = 0;

	} else {

		da_old = startblockval(got.br_startblock);

		da_new = 0;

		nblks = 0;

	}

	qfield = qfield;

	nblks = nblks;



	/*

	 * Set flag value to use in switch statement.

	 * Left-contig is 2, right-contig is 1.

	 */

	switch (((got.br_startoff == del->br_startoff) << 1) |

		(got_endoff == del_endoff)) {

	case 3:

		/*

		 * Matches the whole extent.  Delete the entry.

		 */

		xfs_iext_remove(ip, eidx, 1, BMAP_COWFORK);

		--eidx;

		break;



	case 2:

		/*

		 * Deleting the first part of the extent.

		 */

		trace_xfs_bmap_pre_update(ip, eidx, state, _THIS_IP_);

		xfs_bmbt_set_startoff(ep, del_endoff);

		temp = got.br_blockcount - del->br_blockcount;

		xfs_bmbt_set_blockcount(ep, temp);

		if (delay) {

			temp = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),

				da_old);

			xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));

			trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);

			da_new = temp;

			break;

		}

		xfs_bmbt_set_startblock(ep, del_endblock);

		trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);

		break;



	case 1:

		/*

		 * Deleting the last part of the extent.

		 */

		temp = got.br_blockcount - del->br_blockcount;

		trace_xfs_bmap_pre_update(ip, eidx, state, _THIS_IP_);

		xfs_bmbt_set_blockcount(ep, temp);

		if (delay) {

			temp = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),

				da_old);

			xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));

			trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);

			da_new = temp;

			break;

		}

		trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);

		break;



	case 0:

		/*

		 * Deleting the middle of the extent.

		 */

		temp = del->br_startoff - got.br_startoff;

		trace_xfs_bmap_pre_update(ip, eidx, state, _THIS_IP_);

		xfs_bmbt_set_blockcount(ep, temp);

		new.br_startoff = del_endoff;

		temp2 = got_endoff - del_endoff;

		new.br_blockcount = temp2;

		new.br_state = got.br_state;

		if (!delay) {

			new.br_startblock = del_endblock;

		} else {

			temp = xfs_bmap_worst_indlen(ip, temp);

			xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));

			temp2 = xfs_bmap_worst_indlen(ip, temp2);

			new.br_startblock = nullstartblock((int)temp2);

			da_new = temp + temp2;

			while (da_new > da_old) {

				if (temp) {

					temp--;

					da_new--;

					xfs_bmbt_set_startblock(ep,

						nullstartblock((int)temp));

				}

				if (da_new == da_old)

					break;

				if (temp2) {

					temp2--;

					da_new--;

					new.br_startblock =

						nullstartblock((int)temp2);

				}

			}

		}

		trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);

		xfs_iext_insert(ip, eidx + 1, 1, &new, state);

		++eidx;

		break;

	}



	/*

	 * Account for change in delayed indirect blocks.

	 * Nothing to do for disk quota accounting here.

	 */

	ASSERT(da_old >= da_new);

	if (da_old > da_new)

		xfs_mod_fdblocks(mp, (int64_t)(da_old - da_new), false);



	return error;

}



/*

 * Unmap (remove) blocks from a file.

 * If nexts is nonzero then the number of extents to remove is limited to

fs/xfs/libxfs/xfs_bmap.h

+1 −0
Original line number Diff line number Diff line
@@ -221,6 +221,7 @@ int xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip, 
		xfs_fileoff_t bno, xfs_filblks_t len, int flags,

		xfs_extnum_t nexts, xfs_fsblock_t *firstblock,

		struct xfs_defer_ops *dfops, int *done);

int	xfs_bunmapi_cow(struct xfs_inode *ip, struct xfs_bmbt_irec *del);

int	xfs_check_nostate_extents(struct xfs_ifork *ifp, xfs_extnum_t idx,

		xfs_extnum_t num);

uint	xfs_default_attroffset(struct xfs_inode *ip);