Commit f922cd90 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Dave Chinner
Browse files

xfs: remove an extent from the rmap btree 



Originally-From: Dave Chinner <dchinner@redhat.com>

Now that we have records in the rmap btree, we need to remove them
when extents are freed. This needs to find the relevant record in
the btree and remove/trim/split it accordingly.

[darrick.wong@oracle.com: make rmap routines handle the enlarged keyspace]
[dchinner: remove remaining unused debug printks]
[darrick: fix a bug when growfs in an AG with an rmap ending at EOFS]

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent 0a1b0b38

fs/xfs/libxfs/xfs_rmap.c

+215 −5
Original line number Diff line number Diff line
@@ -133,6 +133,212 @@ xfs_rmap_get_rec( 
	return xfs_rmap_btrec_to_irec(rec, irec);

}



/*

 * Find the extent in the rmap btree and remove it.

 *

 * The record we find should always be an exact match for the extent that we're

 * looking for, since we insert them into the btree without modification.

 *

 * Special Case #1: when growing the filesystem, we "free" an extent when

 * growing the last AG. This extent is new space and so it is not tracked as

 * used space in the btree. The growfs code will pass in an owner of

 * XFS_RMAP_OWN_NULL to indicate that it expected that there is no owner of this

 * extent. We verify that - the extent lookup result in a record that does not

 * overlap.

 *

 * Special Case #2: EFIs do not record the owner of the extent, so when

 * recovering EFIs from the log we pass in XFS_RMAP_OWN_UNKNOWN to tell the rmap

 * btree to ignore the owner (i.e. wildcard match) so we don't trigger

 * corruption checks during log recovery.

 */

STATIC int

xfs_rmap_unmap(

	struct xfs_btree_cur	*cur,

	xfs_agblock_t		bno,

	xfs_extlen_t		len,

	bool			unwritten,

	struct xfs_owner_info	*oinfo)

{

	struct xfs_mount	*mp = cur->bc_mp;

	struct xfs_rmap_irec	ltrec;

	uint64_t		ltoff;

	int			error = 0;

	int			i;

	uint64_t		owner;

	uint64_t		offset;

	unsigned int		flags;

	bool			ignore_off;



	xfs_owner_info_unpack(oinfo, &owner, &offset, &flags);

	ignore_off = XFS_RMAP_NON_INODE_OWNER(owner) ||

			(flags & XFS_RMAP_BMBT_BLOCK);

	if (unwritten)

		flags |= XFS_RMAP_UNWRITTEN;

	trace_xfs_rmap_unmap(mp, cur->bc_private.a.agno, bno, len,

			unwritten, oinfo);



	/*

	 * We should always have a left record because there's a static record

	 * for the AG headers at rm_startblock == 0 created by mkfs/growfs that

	 * will not ever be removed from the tree.

	 */

	error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, flags, &i);

	if (error)

		goto out_error;

	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);



	error = xfs_rmap_get_rec(cur, &ltrec, &i);

	if (error)

		goto out_error;

	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);

	trace_xfs_rmap_lookup_le_range_result(cur->bc_mp,

			cur->bc_private.a.agno, ltrec.rm_startblock,

			ltrec.rm_blockcount, ltrec.rm_owner,

			ltrec.rm_offset, ltrec.rm_flags);

	ltoff = ltrec.rm_offset;



	/*

	 * For growfs, the incoming extent must be beyond the left record we

	 * just found as it is new space and won't be used by anyone. This is

	 * just a corruption check as we don't actually do anything with this

	 * extent.  Note that we need to use >= instead of > because it might

	 * be the case that the "left" extent goes all the way to EOFS.

	 */

	if (owner == XFS_RMAP_OWN_NULL) {

		XFS_WANT_CORRUPTED_GOTO(mp, bno >= ltrec.rm_startblock +

						ltrec.rm_blockcount, out_error);

		goto out_done;

	}



	/* Make sure the unwritten flag matches. */

	XFS_WANT_CORRUPTED_GOTO(mp, (flags & XFS_RMAP_UNWRITTEN) ==

			(ltrec.rm_flags & XFS_RMAP_UNWRITTEN), out_error);



	/* Make sure the extent we found covers the entire freeing range. */

	XFS_WANT_CORRUPTED_GOTO(mp, ltrec.rm_startblock <= bno &&

		ltrec.rm_startblock + ltrec.rm_blockcount >=

		bno + len, out_error);



	/* Make sure the owner matches what we expect to find in the tree. */

	XFS_WANT_CORRUPTED_GOTO(mp, owner == ltrec.rm_owner ||

				    XFS_RMAP_NON_INODE_OWNER(owner), out_error);



	/* Check the offset, if necessary. */

	if (!XFS_RMAP_NON_INODE_OWNER(owner)) {

		if (flags & XFS_RMAP_BMBT_BLOCK) {

			XFS_WANT_CORRUPTED_GOTO(mp,

					ltrec.rm_flags & XFS_RMAP_BMBT_BLOCK,

					out_error);

		} else {

			XFS_WANT_CORRUPTED_GOTO(mp,

					ltrec.rm_offset <= offset, out_error);

			XFS_WANT_CORRUPTED_GOTO(mp,

					ltoff + ltrec.rm_blockcount >= offset + len,

					out_error);

		}

	}



	if (ltrec.rm_startblock == bno && ltrec.rm_blockcount == len) {

		/* exact match, simply remove the record from rmap tree */

		trace_xfs_rmap_delete(mp, cur->bc_private.a.agno,

				ltrec.rm_startblock, ltrec.rm_blockcount,

				ltrec.rm_owner, ltrec.rm_offset,

				ltrec.rm_flags);

		error = xfs_btree_delete(cur, &i);

		if (error)

			goto out_error;

		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);

	} else if (ltrec.rm_startblock == bno) {

		/*

		 * overlap left hand side of extent: move the start, trim the

		 * length and update the current record.

		 *

		 *       ltbno                ltlen

		 * Orig:    |oooooooooooooooooooo|

		 * Freeing: |fffffffff|

		 * Result:            |rrrrrrrrrr|

		 *         bno       len

		 */

		ltrec.rm_startblock += len;

		ltrec.rm_blockcount -= len;

		if (!ignore_off)

			ltrec.rm_offset += len;

		error = xfs_rmap_update(cur, &ltrec);

		if (error)

			goto out_error;

	} else if (ltrec.rm_startblock + ltrec.rm_blockcount == bno + len) {

		/*

		 * overlap right hand side of extent: trim the length and update

		 * the current record.

		 *

		 *       ltbno                ltlen

		 * Orig:    |oooooooooooooooooooo|

		 * Freeing:            |fffffffff|

		 * Result:  |rrrrrrrrrr|

		 *                    bno       len

		 */

		ltrec.rm_blockcount -= len;

		error = xfs_rmap_update(cur, &ltrec);

		if (error)

			goto out_error;

	} else {



		/*

		 * overlap middle of extent: trim the length of the existing

		 * record to the length of the new left-extent size, increment

		 * the insertion position so we can insert a new record

		 * containing the remaining right-extent space.

		 *

		 *       ltbno                ltlen

		 * Orig:    |oooooooooooooooooooo|

		 * Freeing:       |fffffffff|

		 * Result:  |rrrrr|         |rrrr|

		 *               bno       len

		 */

		xfs_extlen_t	orig_len = ltrec.rm_blockcount;



		ltrec.rm_blockcount = bno - ltrec.rm_startblock;

		error = xfs_rmap_update(cur, &ltrec);

		if (error)

			goto out_error;



		error = xfs_btree_increment(cur, 0, &i);

		if (error)

			goto out_error;



		cur->bc_rec.r.rm_startblock = bno + len;

		cur->bc_rec.r.rm_blockcount = orig_len - len -

						     ltrec.rm_blockcount;

		cur->bc_rec.r.rm_owner = ltrec.rm_owner;

		if (ignore_off)

			cur->bc_rec.r.rm_offset = 0;

		else

			cur->bc_rec.r.rm_offset = offset + len;

		cur->bc_rec.r.rm_flags = flags;

		trace_xfs_rmap_insert(mp, cur->bc_private.a.agno,

				cur->bc_rec.r.rm_startblock,

				cur->bc_rec.r.rm_blockcount,

				cur->bc_rec.r.rm_owner,

				cur->bc_rec.r.rm_offset,

				cur->bc_rec.r.rm_flags);

		error = xfs_btree_insert(cur, &i);

		if (error)

			goto out_error;

	}



out_done:

	trace_xfs_rmap_unmap_done(mp, cur->bc_private.a.agno, bno, len,

			unwritten, oinfo);

out_error:

	if (error)

		trace_xfs_rmap_unmap_error(mp, cur->bc_private.a.agno,

				error, _RET_IP_);

	return error;

}



/*

 * Remove a reference to an extent in the rmap btree.

 */

int

xfs_rmap_free(

	struct xfs_trans	*tp,
@@ -143,19 +349,23 @@ xfs_rmap_free( 
	struct xfs_owner_info	*oinfo)

{

	struct xfs_mount	*mp = tp->t_mountp;

	int			error = 0;

	struct xfs_btree_cur	*cur;

	int			error;



	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))

		return 0;



	trace_xfs_rmap_unmap(mp, agno, bno, len, false, oinfo);

	if (1)

	cur = xfs_rmapbt_init_cursor(mp, tp, agbp, agno);



	error = xfs_rmap_unmap(cur, bno, len, false, oinfo);

	if (error)

		goto out_error;

	trace_xfs_rmap_unmap_done(mp, agno, bno, len, false, oinfo);



	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);

	return 0;



out_error:

	trace_xfs_rmap_unmap_error(mp, agno, error, _RET_IP_);

	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);

	return error;

}

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