Merge tag 'xfs-rmap-for-linus-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs

Pull more xfs updates from Dave Chinner:
 "This is the second part of the XFS updates for this merge cycle, and
  contains the new reverse block mapping feature for XFS.

  Reverse mapping allows us to track the owner of a specific block on
  disk precisely.  It is implemented as a set of btrees (one per
  allocation group) that track the owners of allocated extents.
  Effectively it is a "used space tree" that is updated when we allocate
  or free extents.  i.e. it is coherent with the free space btrees we
  already maintain and never overlaps with them.

  This reverse mapping infrastructure is the building block of several
  upcoming features - reflink, copy-on-write data, dedupe, online
  metadata and data scrubbing, highly accurate bad sector/data loss
  reporting to users, and significantly improved reconstruction of
  damaged and corrupted filesystems.  There's a lot of new stuff coming
  along in the next couple of cycles,a nd it all builds in the rmap
  infrastructure.

  As such, it's a huge chunk of new code with new on-disk format
  features and internal infrastructure.  It warns at mount time as an
  experimental feature and that it may eat data (as we do with all new
  on-disk features until they stabilise).  We have not released
  userspace suport for it yet - userspace support currently requires
  download from Darrick's xfsprogs repo and build from source, so the
  access to this feature is really developer/tester only at this point.
  Initial userspace support will be released at the same time kernel
  with this code in it is released.

  The new rmap enabled code regresses 3 xfstests - all are ENOSPC
  related corner cases, one of which Darrick posted a fix for a few
  hours ago.  The other two are fixed by infrastructure that is part of
  the upcoming reflink patchset.  This new ENOSPC infrastructure
  requires a on-disk format tweak required to keep mount times in
  check - we need to keep an on-disk count of allocated rmapbt blocks so
  we don't have to scan the entire btrees at mount time to count them.

  This is currently being tested and will be part of the fixes sent in
  the next week or two so users will not be exposed to this change"

* tag 'xfs-rmap-for-linus-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (52 commits)
  xfs: move (and rename) the deferred bmap-free tracepoints
  xfs: collapse single use static functions
  xfs: remove unnecessary parentheses from log redo item recovery functions
  xfs: remove the extents array from the rmap update done log item
  xfs: in btree_lshift, only allocate temporary cursor when needed
  xfs: remove unnecesary lshift/rshift key initialization
  xfs: remove the get*keys and update_keys btree ops pointers
  xfs: enable the rmap btree functionality
  xfs: don't update rmapbt when fixing agfl
  xfs: disable XFS_IOC_SWAPEXT when rmap btree is enabled
  xfs: add rmap btree block detection to log recovery
  xfs: add rmap btree geometry feature flag
  xfs: propagate bmap updates to rmapbt
  xfs: enable the xfs_defer mechanism to process rmaps to update
  xfs: log rmap intent items
  xfs: create rmap update intent log items
  xfs: add rmap btree insert and delete helpers
  xfs: convert unwritten status of reverse mappings
  xfs: remove an extent from the rmap btree
  xfs: add an extent to the rmap btree
  ...

1 files changed, 1399 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
new file mode 100644
index 000000000000..73d05407d663
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -0,0 +1,1399 @@
+/*
+ * Copyright (c) 2014 Red Hat, Inc.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_bit.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_btree.h"
+#include "xfs_trans.h"
+#include "xfs_alloc.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_trans_space.h"
+#include "xfs_trace.h"
+#include "xfs_error.h"
+#include "xfs_extent_busy.h"
+#include "xfs_bmap.h"
+#include "xfs_inode.h"
+
+/*
+ * Lookup the first record less than or equal to [bno, len, owner, offset]
+ * in the btree given by cur.
+ */
+int
+xfs_rmap_lookup_le(
+	struct xfs_btree_cur	*cur,
+	xfs_agblock_t		bno,
+	xfs_extlen_t		len,
+	uint64_t		owner,
+	uint64_t		offset,
+	unsigned int		flags,
+	int			*stat)
+{
+	cur->bc_rec.r.rm_startblock = bno;
+	cur->bc_rec.r.rm_blockcount = len;
+	cur->bc_rec.r.rm_owner = owner;
+	cur->bc_rec.r.rm_offset = offset;
+	cur->bc_rec.r.rm_flags = flags;
+	return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
+}
+
+/*
+ * Lookup the record exactly matching [bno, len, owner, offset]
+ * in the btree given by cur.
+ */
+int
+xfs_rmap_lookup_eq(
+	struct xfs_btree_cur	*cur,
+	xfs_agblock_t		bno,
+	xfs_extlen_t		len,
+	uint64_t		owner,
+	uint64_t		offset,
+	unsigned int		flags,
+	int			*stat)
+{
+	cur->bc_rec.r.rm_startblock = bno;
+	cur->bc_rec.r.rm_blockcount = len;
+	cur->bc_rec.r.rm_owner = owner;
+	cur->bc_rec.r.rm_offset = offset;
+	cur->bc_rec.r.rm_flags = flags;
+	return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
+}
+
+/*
+ * Update the record referred to by cur to the value given
+ * by [bno, len, owner, offset].
+ * This either works (return 0) or gets an EFSCORRUPTED error.
+ */
+STATIC int
+xfs_rmap_update(
+	struct xfs_btree_cur	*cur,
+	struct xfs_rmap_irec	*irec)
+{
+	union xfs_btree_rec	rec;
+	int			error;
+
+	trace_xfs_rmap_update(cur->bc_mp, cur->bc_private.a.agno,
+			irec->rm_startblock, irec->rm_blockcount,
+			irec->rm_owner, irec->rm_offset, irec->rm_flags);
+
+	rec.rmap.rm_startblock = cpu_to_be32(irec->rm_startblock);
+	rec.rmap.rm_blockcount = cpu_to_be32(irec->rm_blockcount);
+	rec.rmap.rm_owner = cpu_to_be64(irec->rm_owner);
+	rec.rmap.rm_offset = cpu_to_be64(
+			xfs_rmap_irec_offset_pack(irec));
+	error = xfs_btree_update(cur, &rec);
+	if (error)
+		trace_xfs_rmap_update_error(cur->bc_mp,
+				cur->bc_private.a.agno, error, _RET_IP_);
+	return error;
+}
+
+int
+xfs_rmap_insert(
+	struct xfs_btree_cur	*rcur,
+	xfs_agblock_t		agbno,
+	xfs_extlen_t		len,
+	uint64_t		owner,
+	uint64_t		offset,
+	unsigned int		flags)
+{
+	int			i;
+	int			error;
+
+	trace_xfs_rmap_insert(rcur->bc_mp, rcur->bc_private.a.agno, agbno,
+			len, owner, offset, flags);
+
+	error = xfs_rmap_lookup_eq(rcur, agbno, len, owner, offset, flags, &i);
+	if (error)
+		goto done;
+	XFS_WANT_CORRUPTED_GOTO(rcur->bc_mp, i == 0, done);
+
+	rcur->bc_rec.r.rm_startblock = agbno;
+	rcur->bc_rec.r.rm_blockcount = len;
+	rcur->bc_rec.r.rm_owner = owner;
+	rcur->bc_rec.r.rm_offset = offset;
+	rcur->bc_rec.r.rm_flags = flags;
+	error = xfs_btree_insert(rcur, &i);
+	if (error)
+		goto done;
+	XFS_WANT_CORRUPTED_GOTO(rcur->bc_mp, i == 1, done);
+done:
+	if (error)
+		trace_xfs_rmap_insert_error(rcur->bc_mp,
+				rcur->bc_private.a.agno, error, _RET_IP_);
+	return error;
+}
+
+static int
+xfs_rmap_btrec_to_irec(
+	union xfs_btree_rec	*rec,
+	struct xfs_rmap_irec	*irec)
+{
+	irec->rm_flags = 0;
+	irec->rm_startblock = be32_to_cpu(rec->rmap.rm_startblock);
+	irec->rm_blockcount = be32_to_cpu(rec->rmap.rm_blockcount);
+	irec->rm_owner = be64_to_cpu(rec->rmap.rm_owner);
+	return xfs_rmap_irec_offset_unpack(be64_to_cpu(rec->rmap.rm_offset),
+			irec);
+}
+
+/*
+ * Get the data from the pointed-to record.
+ */
+int
+xfs_rmap_get_rec(
+	struct xfs_btree_cur	*cur,
+	struct xfs_rmap_irec	*irec,
+	int			*stat)
+{
+	union xfs_btree_rec	*rec;
+	int			error;
+
+	error = xfs_btree_get_rec(cur, &rec, stat);
+	if (error || !*stat)
+		return error;
+
+	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,
+	struct xfs_buf		*agbp,
+	xfs_agnumber_t		agno,
+	xfs_agblock_t		bno,
+	xfs_extlen_t		len,
+	struct xfs_owner_info	*oinfo)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xfs_btree_cur	*cur;
+	int			error;
+
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+		return 0;
+
+	cur = xfs_rmapbt_init_cursor(mp, tp, agbp, agno);
+
+	error = xfs_rmap_unmap(cur, bno, len, false, oinfo);
+	if (error)
+		goto out_error;
+
+	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+	return 0;
+
+out_error:
+	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+	return error;
+}
+
+/*
+ * A mergeable rmap must have the same owner and the same values for
+ * the unwritten, attr_fork, and bmbt flags.  The startblock and
+ * offset are checked separately.
+ */
+static bool
+xfs_rmap_is_mergeable(
+	struct xfs_rmap_irec	*irec,
+	uint64_t		owner,
+	unsigned int		flags)
+{
+	if (irec->rm_owner == XFS_RMAP_OWN_NULL)
+		return false;
+	if (irec->rm_owner != owner)
+		return false;
+	if ((flags & XFS_RMAP_UNWRITTEN) ^
+	    (irec->rm_flags & XFS_RMAP_UNWRITTEN))
+		return false;
+	if ((flags & XFS_RMAP_ATTR_FORK) ^
+	    (irec->rm_flags & XFS_RMAP_ATTR_FORK))
+		return false;
+	if ((flags & XFS_RMAP_BMBT_BLOCK) ^
+	    (irec->rm_flags & XFS_RMAP_BMBT_BLOCK))
+		return false;
+	return true;
+}
+
+/*
+ * When we allocate a new block, the first thing we do is add a reference to
+ * the extent in the rmap btree. This takes the form of a [agbno, length,
+ * owner, offset] record.  Flags are encoded in the high bits of the offset
+ * field.
+ */
+STATIC int
+xfs_rmap_map(
+	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;
+	struct xfs_rmap_irec	gtrec;
+	int			have_gt;
+	int			have_lt;
+	int			error = 0;
+	int			i;
+	uint64_t		owner;
+	uint64_t		offset;
+	unsigned int		flags = 0;
+	bool			ignore_off;
+
+	xfs_owner_info_unpack(oinfo, &owner, &offset, &flags);
+	ASSERT(owner != 0);
+	ignore_off = XFS_RMAP_NON_INODE_OWNER(owner) ||
+			(flags & XFS_RMAP_BMBT_BLOCK);
+	if (unwritten)
+		flags |= XFS_RMAP_UNWRITTEN;
+	trace_xfs_rmap_map(mp, cur->bc_private.a.agno, bno, len,
+			unwritten, oinfo);
+
+	/*
+	 * For the initial lookup, look for an exact match or the left-adjacent
+	 * record for our insertion point. This will also give us the record for
+	 * start block contiguity tests.
+	 */
+	error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, flags,
+			&have_lt);
+	if (error)
+		goto out_error;
+	XFS_WANT_CORRUPTED_GOTO(mp, have_lt == 1, out_error);
+
+	error = xfs_rmap_get_rec(cur, &ltrec, &have_lt);
+	if (error)
+		goto out_error;
+	XFS_WANT_CORRUPTED_GOTO(mp, have_lt == 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);
+
+	if (!xfs_rmap_is_mergeable(&ltrec, owner, flags))
+		have_lt = 0;
+
+	XFS_WANT_CORRUPTED_GOTO(mp,
+		have_lt == 0 ||
+		ltrec.rm_startblock + ltrec.rm_blockcount <= bno, out_error);
+
+	/*
+	 * Increment the cursor to see if we have a right-adjacent record to our
+	 * insertion point. This will give us the record for end block
+	 * contiguity tests.
+	 */
+	error = xfs_btree_increment(cur, 0, &have_gt);
+	if (error)
+		goto out_error;
+	if (have_gt) {
+		error = xfs_rmap_get_rec(cur, &gtrec, &have_gt);
+		if (error)
+			goto out_error;
+		XFS_WANT_CORRUPTED_GOTO(mp, have_gt == 1, out_error);
+		XFS_WANT_CORRUPTED_GOTO(mp, bno + len <= gtrec.rm_startblock,
+					out_error);
+		trace_xfs_rmap_find_right_neighbor_result(cur->bc_mp,
+			cur->bc_private.a.agno, gtrec.rm_startblock,
+			gtrec.rm_blockcount, gtrec.rm_owner,
+			gtrec.rm_offset, gtrec.rm_flags);
+		if (!xfs_rmap_is_mergeable(&gtrec, owner, flags))
+			have_gt = 0;
+	}
+
+	/*
+	 * Note: cursor currently points one record to the right of ltrec, even
+	 * if there is no record in the tree to the right.
+	 */
+	if (have_lt &&
+	    ltrec.rm_startblock + ltrec.rm_blockcount == bno &&
+	    (ignore_off || ltrec.rm_offset + ltrec.rm_blockcount == offset)) {
+		/*
+		 * left edge contiguous, merge into left record.
+		 *
+		 *       ltbno     ltlen
+		 * orig:   |ooooooooo|
+		 * adding:           |aaaaaaaaa|
+		 * result: |rrrrrrrrrrrrrrrrrrr|
+		 *                  bno       len
+		 */
+		ltrec.rm_blockcount += len;
+		if (have_gt &&
+		    bno + len == gtrec.rm_startblock &&
+		    (ignore_off || offset + len == gtrec.rm_offset) &&
+		    (unsigned long)ltrec.rm_blockcount + len +
+				gtrec.rm_blockcount <= XFS_RMAP_LEN_MAX) {
+			/*
+			 * right edge also contiguous, delete right record
+			 * and merge into left record.
+			 *
+			 *       ltbno     ltlen    gtbno     gtlen
+			 * orig:   |ooooooooo|         |ooooooooo|
+			 * adding:           |aaaaaaaaa|
+			 * result: |rrrrrrrrrrrrrrrrrrrrrrrrrrrrr|
+			 */
+			ltrec.rm_blockcount += gtrec.rm_blockcount;
+			trace_xfs_rmap_delete(mp, cur->bc_private.a.agno,
+					gtrec.rm_startblock,
+					gtrec.rm_blockcount,
+					gtrec.rm_owner,
+					gtrec.rm_offset,
+					gtrec.rm_flags);
+			error = xfs_btree_delete(cur, &i);
+			if (error)
+				goto out_error;
+			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+		}
+
+		/* point the cursor back to the left record and update */
+		error = xfs_btree_decrement(cur, 0, &have_gt);
+		if (error)
+			goto out_error;
+		error = xfs_rmap_update(cur, &ltrec);
+		if (error)
+			goto out_error;
+	} else if (have_gt &&
+		   bno + len == gtrec.rm_startblock &&
+		   (ignore_off || offset + len == gtrec.rm_offset)) {
+		/*
+		 * right edge contiguous, merge into right record.
+		 *
+		 *                 gtbno     gtlen
+		 * Orig:             |ooooooooo|
+		 * adding: |aaaaaaaaa|
+		 * Result: |rrrrrrrrrrrrrrrrrrr|
+		 *        bno       len
+		 */
+		gtrec.rm_startblock = bno;
+		gtrec.rm_blockcount += len;
+		if (!ignore_off)
+			gtrec.rm_offset = offset;
+		error = xfs_rmap_update(cur, &gtrec);
+		if (error)
+			goto out_error;
+	} else {
+		/*
+		 * no contiguous edge with identical owner, insert
+		 * new record at current cursor position.
+		 */
+		cur->bc_rec.r.rm_startblock = bno;
+		cur->bc_rec.r.rm_blockcount = len;
+		cur->bc_rec.r.rm_owner = owner;
+		cur->bc_rec.r.rm_offset = offset;
+		cur->bc_rec.r.rm_flags = flags;
+		trace_xfs_rmap_insert(mp, cur->bc_private.a.agno, bno, len,
+			owner, offset, flags);
+		error = xfs_btree_insert(cur, &i);
+		if (error)
+			goto out_error;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+	}
+
+	trace_xfs_rmap_map_done(mp, cur->bc_private.a.agno, bno, len,
+			unwritten, oinfo);
+out_error:
+	if (error)
+		trace_xfs_rmap_map_error(mp, cur->bc_private.a.agno,
+				error, _RET_IP_);
+	return error;
+}
+
+/*
+ * Add a reference to an extent in the rmap btree.
+ */
+int
+xfs_rmap_alloc(
+	struct xfs_trans	*tp,
+	struct xfs_buf		*agbp,
+	xfs_agnumber_t		agno,
+	xfs_agblock_t		bno,
+	xfs_extlen_t		len,
+	struct xfs_owner_info	*oinfo)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xfs_btree_cur	*cur;
+	int			error;
+
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+		return 0;
+
+	cur = xfs_rmapbt_init_cursor(mp, tp, agbp, agno);
+	error = xfs_rmap_map(cur, bno, len, false, oinfo);
+	if (error)
+		goto out_error;
+
+	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+	return 0;
+
+out_error:
+	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+	return error;
+}
+
+#define RMAP_LEFT_CONTIG	(1 << 0)
+#define RMAP_RIGHT_CONTIG	(1 << 1)
+#define RMAP_LEFT_FILLING	(1 << 2)
+#define RMAP_RIGHT_FILLING	(1 << 3)
+#define RMAP_LEFT_VALID		(1 << 6)
+#define RMAP_RIGHT_VALID	(1 << 7)
+
+#define LEFT		r[0]
+#define RIGHT		r[1]
+#define PREV		r[2]
+#define NEW		r[3]
+
+/*
+ * Convert an unwritten extent to a real extent or vice versa.
+ * Does not handle overlapping extents.
+ */
+STATIC int
+xfs_rmap_convert(
+	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	r[4];	/* neighbor extent entries */
+					/* left is 0, right is 1, prev is 2 */
+					/* new is 3 */
+	uint64_t		owner;
+	uint64_t		offset;
+	uint64_t		new_endoff;
+	unsigned int		oldext;
+	unsigned int		newext;
+	unsigned int		flags = 0;
+	int			i;
+	int			state = 0;
+	int			error;
+
+	xfs_owner_info_unpack(oinfo, &owner, &offset, &flags);
+	ASSERT(!(XFS_RMAP_NON_INODE_OWNER(owner) ||
+			(flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))));
+	oldext = unwritten ? XFS_RMAP_UNWRITTEN : 0;
+	new_endoff = offset + len;
+	trace_xfs_rmap_convert(mp, cur->bc_private.a.agno, bno, len,
+			unwritten, oinfo);
+
+	/*
+	 * For the initial lookup, look for an exact match or the left-adjacent
+	 * record for our insertion point. This will also give us the record for
+	 * start block contiguity tests.
+	 */
+	error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, oldext, &i);
+	if (error)
+		goto done;
+	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+
+	error = xfs_rmap_get_rec(cur, &PREV, &i);
+	if (error)
+		goto done;
+	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+	trace_xfs_rmap_lookup_le_range_result(cur->bc_mp,
+			cur->bc_private.a.agno, PREV.rm_startblock,
+			PREV.rm_blockcount, PREV.rm_owner,
+			PREV.rm_offset, PREV.rm_flags);
+
+	ASSERT(PREV.rm_offset <= offset);
+	ASSERT(PREV.rm_offset + PREV.rm_blockcount >= new_endoff);
+	ASSERT((PREV.rm_flags & XFS_RMAP_UNWRITTEN) == oldext);
+	newext = ~oldext & XFS_RMAP_UNWRITTEN;
+
+	/*
+	 * Set flags determining what part of the previous oldext allocation
+	 * extent is being replaced by a newext allocation.
+	 */
+	if (PREV.rm_offset == offset)
+		state |= RMAP_LEFT_FILLING;
+	if (PREV.rm_offset + PREV.rm_blockcount == new_endoff)
+		state |= RMAP_RIGHT_FILLING;
+
+	/*
+	 * Decrement the cursor to see if we have a left-adjacent record to our
+	 * insertion point. This will give us the record for end block
+	 * contiguity tests.
+	 */
+	error = xfs_btree_decrement(cur, 0, &i);
+	if (error)
+		goto done;
+	if (i) {
+		state |= RMAP_LEFT_VALID;
+		error = xfs_rmap_get_rec(cur, &LEFT, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		XFS_WANT_CORRUPTED_GOTO(mp,
+				LEFT.rm_startblock + LEFT.rm_blockcount <= bno,
+				done);
+		trace_xfs_rmap_find_left_neighbor_result(cur->bc_mp,
+				cur->bc_private.a.agno, LEFT.rm_startblock,
+				LEFT.rm_blockcount, LEFT.rm_owner,
+				LEFT.rm_offset, LEFT.rm_flags);
+		if (LEFT.rm_startblock + LEFT.rm_blockcount == bno &&
+		    LEFT.rm_offset + LEFT.rm_blockcount == offset &&
+		    xfs_rmap_is_mergeable(&LEFT, owner, newext))
+			state |= RMAP_LEFT_CONTIG;
+	}
+
+	/*
+	 * Increment the cursor to see if we have a right-adjacent record to our
+	 * insertion point. This will give us the record for end block
+	 * contiguity tests.
+	 */
+	error = xfs_btree_increment(cur, 0, &i);
+	if (error)
+		goto done;
+	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+	error = xfs_btree_increment(cur, 0, &i);
+	if (error)
+		goto done;
+	if (i) {
+		state |= RMAP_RIGHT_VALID;
+		error = xfs_rmap_get_rec(cur, &RIGHT, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		XFS_WANT_CORRUPTED_GOTO(mp, bno + len <= RIGHT.rm_startblock,
+					done);
+		trace_xfs_rmap_find_right_neighbor_result(cur->bc_mp,
+				cur->bc_private.a.agno, RIGHT.rm_startblock,
+				RIGHT.rm_blockcount, RIGHT.rm_owner,
+				RIGHT.rm_offset, RIGHT.rm_flags);
+		if (bno + len == RIGHT.rm_startblock &&
+		    offset + len == RIGHT.rm_offset &&
+		    xfs_rmap_is_mergeable(&RIGHT, owner, newext))
+			state |= RMAP_RIGHT_CONTIG;
+	}
+
+	/* check that left + prev + right is not too long */
+	if ((state & (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
+			 RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG)) ==
+	    (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
+	     RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG) &&
+	    (unsigned long)LEFT.rm_blockcount + len +
+	     RIGHT.rm_blockcount > XFS_RMAP_LEN_MAX)
+		state &= ~RMAP_RIGHT_CONTIG;
+
+	trace_xfs_rmap_convert_state(mp, cur->bc_private.a.agno, state,
+			_RET_IP_);
+
+	/* reset the cursor back to PREV */
+	error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, oldext, &i);
+	if (error)
+		goto done;
+	XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+
+	/*
+	 * Switch out based on the FILLING and CONTIG state bits.
+	 */
+	switch (state & (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
+			 RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG)) {
+	case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
+	     RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * The left and right neighbors are both contiguous with new.
+		 */
+		error = xfs_btree_increment(cur, 0, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		trace_xfs_rmap_delete(mp, cur->bc_private.a.agno,
+				RIGHT.rm_startblock, RIGHT.rm_blockcount,
+				RIGHT.rm_owner, RIGHT.rm_offset,
+				RIGHT.rm_flags);
+		error = xfs_btree_delete(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		error = xfs_btree_decrement(cur, 0, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		trace_xfs_rmap_delete(mp, cur->bc_private.a.agno,
+				PREV.rm_startblock, PREV.rm_blockcount,
+				PREV.rm_owner, PREV.rm_offset,
+				PREV.rm_flags);
+		error = xfs_btree_delete(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		error = xfs_btree_decrement(cur, 0, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		NEW = LEFT;
+		NEW.rm_blockcount += PREV.rm_blockcount + RIGHT.rm_blockcount;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		break;
+
+	case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * The left neighbor is contiguous, the right is not.
+		 */
+		trace_xfs_rmap_delete(mp, cur->bc_private.a.agno,
+				PREV.rm_startblock, PREV.rm_blockcount,
+				PREV.rm_owner, PREV.rm_offset,
+				PREV.rm_flags);
+		error = xfs_btree_delete(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		error = xfs_btree_decrement(cur, 0, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		NEW = LEFT;
+		NEW.rm_blockcount += PREV.rm_blockcount;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		break;
+
+	case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * The right neighbor is contiguous, the left is not.
+		 */
+		error = xfs_btree_increment(cur, 0, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		trace_xfs_rmap_delete(mp, cur->bc_private.a.agno,
+				RIGHT.rm_startblock, RIGHT.rm_blockcount,
+				RIGHT.rm_owner, RIGHT.rm_offset,
+				RIGHT.rm_flags);
+		error = xfs_btree_delete(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		error = xfs_btree_decrement(cur, 0, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		NEW = PREV;
+		NEW.rm_blockcount = len + RIGHT.rm_blockcount;
+		NEW.rm_flags = newext;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		break;
+
+	case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * Neither the left nor right neighbors are contiguous with
+		 * the new one.
+		 */
+		NEW = PREV;
+		NEW.rm_flags = newext;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		break;
+
+	case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG:
+		/*
+		 * Setting the first part of a previous oldext extent to newext.
+		 * The left neighbor is contiguous.
+		 */
+		NEW = PREV;
+		NEW.rm_offset += len;
+		NEW.rm_startblock += len;
+		NEW.rm_blockcount -= len;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		error = xfs_btree_decrement(cur, 0, &i);
+		if (error)
+			goto done;
+		NEW = LEFT;
+		NEW.rm_blockcount += len;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		break;
+
+	case RMAP_LEFT_FILLING:
+		/*
+		 * Setting the first part of a previous oldext extent to newext.
+		 * The left neighbor is not contiguous.
+		 */
+		NEW = PREV;
+		NEW.rm_startblock += len;
+		NEW.rm_offset += len;
+		NEW.rm_blockcount -= len;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		NEW.rm_startblock = bno;
+		NEW.rm_owner = owner;
+		NEW.rm_offset = offset;
+		NEW.rm_blockcount = len;
+		NEW.rm_flags = newext;
+		cur->bc_rec.r = NEW;
+		trace_xfs_rmap_insert(mp, cur->bc_private.a.agno, bno,
+				len, owner, offset, newext);
+		error = xfs_btree_insert(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		break;
+
+	case RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
+		/*
+		 * Setting the last part of a previous oldext extent to newext.
+		 * The right neighbor is contiguous with the new allocation.
+		 */
+		NEW = PREV;
+		NEW.rm_blockcount -= len;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		error = xfs_btree_increment(cur, 0, &i);
+		if (error)
+			goto done;
+		NEW = RIGHT;
+		NEW.rm_offset = offset;
+		NEW.rm_startblock = bno;
+		NEW.rm_blockcount += len;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		break;
+
+	case RMAP_RIGHT_FILLING:
+		/*
+		 * Setting the last part of a previous oldext extent to newext.
+		 * The right neighbor is not contiguous.
+		 */
+		NEW = PREV;
+		NEW.rm_blockcount -= len;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		error = xfs_rmap_lookup_eq(cur, bno, len, owner, offset,
+				oldext, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
+		NEW.rm_startblock = bno;
+		NEW.rm_owner = owner;
+		NEW.rm_offset = offset;
+		NEW.rm_blockcount = len;
+		NEW.rm_flags = newext;
+		cur->bc_rec.r = NEW;
+		trace_xfs_rmap_insert(mp, cur->bc_private.a.agno, bno,
+				len, owner, offset, newext);
+		error = xfs_btree_insert(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		break;
+
+	case 0:
+		/*
+		 * Setting the middle part of a previous oldext extent to
+		 * newext.  Contiguity is impossible here.
+		 * One extent becomes three extents.
+		 */
+		/* new right extent - oldext */
+		NEW.rm_startblock = bno + len;
+		NEW.rm_owner = owner;
+		NEW.rm_offset = new_endoff;
+		NEW.rm_blockcount = PREV.rm_offset + PREV.rm_blockcount -
+				new_endoff;
+		NEW.rm_flags = PREV.rm_flags;
+		error = xfs_rmap_update(cur, &NEW);
+		if (error)
+			goto done;
+		/* new left extent - oldext */
+		NEW = PREV;
+		NEW.rm_blockcount = offset - PREV.rm_offset;
+		cur->bc_rec.r = NEW;
+		trace_xfs_rmap_insert(mp, cur->bc_private.a.agno,
+				NEW.rm_startblock, NEW.rm_blockcount,
+				NEW.rm_owner, NEW.rm_offset,
+				NEW.rm_flags);
+		error = xfs_btree_insert(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		/*
+		 * Reset the cursor to the position of the new extent
+		 * we are about to insert as we can't trust it after
+		 * the previous insert.
+		 */
+		error = xfs_rmap_lookup_eq(cur, bno, len, owner, offset,
+				oldext, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
+		/* new middle extent - newext */
+		cur->bc_rec.r.rm_flags &= ~XFS_RMAP_UNWRITTEN;
+		cur->bc_rec.r.rm_flags |= newext;
+		trace_xfs_rmap_insert(mp, cur->bc_private.a.agno, bno, len,
+				owner, offset, newext);
+		error = xfs_btree_insert(cur, &i);
+		if (error)
+			goto done;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
+		break;
+
+	case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
+	case RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
+	case RMAP_LEFT_FILLING | RMAP_RIGHT_CONTIG:
+	case RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG:
+	case RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
+	case RMAP_LEFT_CONTIG:
+	case RMAP_RIGHT_CONTIG:
+		/*
+		 * These cases are all impossible.
+		 */
+		ASSERT(0);
+	}
+
+	trace_xfs_rmap_convert_done(mp, cur->bc_private.a.agno, bno, len,
+			unwritten, oinfo);
+done:
+	if (error)
+		trace_xfs_rmap_convert_error(cur->bc_mp,
+				cur->bc_private.a.agno, error, _RET_IP_);
+	return error;
+}
+
+#undef	NEW
+#undef	LEFT
+#undef	RIGHT
+#undef	PREV
+
+struct xfs_rmap_query_range_info {
+	xfs_rmap_query_range_fn	fn;
+	void				*priv;
+};
+
+/* Format btree record and pass to our callback. */
+STATIC int
+xfs_rmap_query_range_helper(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_rec	*rec,
+	void			*priv)
+{
+	struct xfs_rmap_query_range_info	*query = priv;
+	struct xfs_rmap_irec			irec;
+	int					error;
+
+	error = xfs_rmap_btrec_to_irec(rec, &irec);
+	if (error)
+		return error;
+	return query->fn(cur, &irec, query->priv);
+}
+
+/* Find all rmaps between two keys. */
+int
+xfs_rmap_query_range(
+	struct xfs_btree_cur		*cur,
+	struct xfs_rmap_irec		*low_rec,
+	struct xfs_rmap_irec		*high_rec,
+	xfs_rmap_query_range_fn	fn,
+	void				*priv)
+{
+	union xfs_btree_irec		low_brec;
+	union xfs_btree_irec		high_brec;
+	struct xfs_rmap_query_range_info	query;
+
+	low_brec.r = *low_rec;
+	high_brec.r = *high_rec;
+	query.priv = priv;
+	query.fn = fn;
+	return xfs_btree_query_range(cur, &low_brec, &high_brec,
+			xfs_rmap_query_range_helper, &query);
+}
+
+/* Clean up after calling xfs_rmap_finish_one. */
+void
+xfs_rmap_finish_one_cleanup(
+	struct xfs_trans	*tp,
+	struct xfs_btree_cur	*rcur,
+	int			error)
+{
+	struct xfs_buf		*agbp;
+
+	if (rcur == NULL)
+		return;
+	agbp = rcur->bc_private.a.agbp;
+	xfs_btree_del_cursor(rcur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
+	if (error)
+		xfs_trans_brelse(tp, agbp);
+}
+
+/*
+ * Process one of the deferred rmap operations.  We pass back the
+ * btree cursor to maintain our lock on the rmapbt between calls.
+ * This saves time and eliminates a buffer deadlock between the
+ * superblock and the AGF because we'll always grab them in the same
+ * order.
+ */
+int
+xfs_rmap_finish_one(
+	struct xfs_trans		*tp,
+	enum xfs_rmap_intent_type	type,
+	__uint64_t			owner,
+	int				whichfork,
+	xfs_fileoff_t			startoff,
+	xfs_fsblock_t			startblock,
+	xfs_filblks_t			blockcount,
+	xfs_exntst_t			state,
+	struct xfs_btree_cur		**pcur)
+{
+	struct xfs_mount		*mp = tp->t_mountp;
+	struct xfs_btree_cur		*rcur;
+	struct xfs_buf			*agbp = NULL;
+	int				error = 0;
+	xfs_agnumber_t			agno;
+	struct xfs_owner_info		oinfo;
+	xfs_agblock_t			bno;
+	bool				unwritten;
+
+	agno = XFS_FSB_TO_AGNO(mp, startblock);
+	ASSERT(agno != NULLAGNUMBER);
+	bno = XFS_FSB_TO_AGBNO(mp, startblock);
+
+	trace_xfs_rmap_deferred(mp, agno, type, bno, owner, whichfork,
+			startoff, blockcount, state);
+
+	if (XFS_TEST_ERROR(false, mp,
+			XFS_ERRTAG_RMAP_FINISH_ONE,
+			XFS_RANDOM_RMAP_FINISH_ONE))
+		return -EIO;
+
+	/*
+	 * If we haven't gotten a cursor or the cursor AG doesn't match
+	 * the startblock, get one now.
+	 */
+	rcur = *pcur;
+	if (rcur != NULL && rcur->bc_private.a.agno != agno) {
+		xfs_rmap_finish_one_cleanup(tp, rcur, 0);
+		rcur = NULL;
+		*pcur = NULL;
+	}
+	if (rcur == NULL) {
+		/*
+		 * Refresh the freelist before we start changing the
+		 * rmapbt, because a shape change could cause us to
+		 * allocate blocks.
+		 */
+		error = xfs_free_extent_fix_freelist(tp, agno, &agbp);
+		if (error)
+			return error;
+		if (!agbp)
+			return -EFSCORRUPTED;
+
+		rcur = xfs_rmapbt_init_cursor(mp, tp, agbp, agno);
+		if (!rcur) {
+			error = -ENOMEM;
+			goto out_cur;
+		}
+	}
+	*pcur = rcur;
+
+	xfs_rmap_ino_owner(&oinfo, owner, whichfork, startoff);
+	unwritten = state == XFS_EXT_UNWRITTEN;
+	bno = XFS_FSB_TO_AGBNO(rcur->bc_mp, startblock);
+
+	switch (type) {
+	case XFS_RMAP_ALLOC:
+	case XFS_RMAP_MAP:
+		error = xfs_rmap_map(rcur, bno, blockcount, unwritten, &oinfo);
+		break;
+	case XFS_RMAP_FREE:
+	case XFS_RMAP_UNMAP:
+		error = xfs_rmap_unmap(rcur, bno, blockcount, unwritten,
+				&oinfo);
+		break;
+	case XFS_RMAP_CONVERT:
+		error = xfs_rmap_convert(rcur, bno, blockcount, !unwritten,
+				&oinfo);
+		break;
+	default:
+		ASSERT(0);
+		error = -EFSCORRUPTED;
+	}
+	return error;
+
+out_cur:
+	xfs_trans_brelse(tp, agbp);
+
+	return error;
+}
+
+/*
+ * Don't defer an rmap if we aren't an rmap filesystem.
+ */
+static bool
+xfs_rmap_update_is_needed(
+	struct xfs_mount	*mp)
+{
+	return xfs_sb_version_hasrmapbt(&mp->m_sb);
+}
+
+/*
+ * Record a rmap intent; the list is kept sorted first by AG and then by
+ * increasing age.
+ */
+static int
+__xfs_rmap_add(
+	struct xfs_mount		*mp,
+	struct xfs_defer_ops		*dfops,
+	enum xfs_rmap_intent_type	type,
+	__uint64_t			owner,
+	int				whichfork,
+	struct xfs_bmbt_irec		*bmap)
+{
+	struct xfs_rmap_intent	*ri;
+
+	trace_xfs_rmap_defer(mp, XFS_FSB_TO_AGNO(mp, bmap->br_startblock),
+			type,
+			XFS_FSB_TO_AGBNO(mp, bmap->br_startblock),
+			owner, whichfork,
+			bmap->br_startoff,
+			bmap->br_blockcount,
+			bmap->br_state);
+
+	ri = kmem_alloc(sizeof(struct xfs_rmap_intent), KM_SLEEP | KM_NOFS);
+	INIT_LIST_HEAD(&ri->ri_list);
+	ri->ri_type = type;
+	ri->ri_owner = owner;
+	ri->ri_whichfork = whichfork;
+	ri->ri_bmap = *bmap;
+
+	xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_RMAP, &ri->ri_list);
+	return 0;
+}
+
+/* Map an extent into a file. */
+int
+xfs_rmap_map_extent(
+	struct xfs_mount	*mp,
+	struct xfs_defer_ops	*dfops,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_bmbt_irec	*PREV)
+{
+	if (!xfs_rmap_update_is_needed(mp))
+		return 0;
+
+	return __xfs_rmap_add(mp, dfops, XFS_RMAP_MAP, ip->i_ino,
+			whichfork, PREV);
+}
+
+/* Unmap an extent out of a file. */
+int
+xfs_rmap_unmap_extent(
+	struct xfs_mount	*mp,
+	struct xfs_defer_ops	*dfops,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_bmbt_irec	*PREV)
+{
+	if (!xfs_rmap_update_is_needed(mp))
+		return 0;
+
+	return __xfs_rmap_add(mp, dfops, XFS_RMAP_UNMAP, ip->i_ino,
+			whichfork, PREV);
+}
+
+/* Convert a data fork extent from unwritten to real or vice versa. */
+int
+xfs_rmap_convert_extent(
+	struct xfs_mount	*mp,
+	struct xfs_defer_ops	*dfops,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_bmbt_irec	*PREV)
+{
+	if (!xfs_rmap_update_is_needed(mp))
+		return 0;
+
+	return __xfs_rmap_add(mp, dfops, XFS_RMAP_CONVERT, ip->i_ino,
+			whichfork, PREV);
+}
+
+/* Schedule the creation of an rmap for non-file data. */
+int
+xfs_rmap_alloc_extent(
+	struct xfs_mount	*mp,
+	struct xfs_defer_ops	*dfops,
+	xfs_agnumber_t		agno,
+	xfs_agblock_t		bno,
+	xfs_extlen_t		len,
+	__uint64_t		owner)
+{
+	struct xfs_bmbt_irec	bmap;
+
+	if (!xfs_rmap_update_is_needed(mp))
+		return 0;
+
+	bmap.br_startblock = XFS_AGB_TO_FSB(mp, agno, bno);
+	bmap.br_blockcount = len;
+	bmap.br_startoff = 0;
+	bmap.br_state = XFS_EXT_NORM;
+
+	return __xfs_rmap_add(mp, dfops, XFS_RMAP_ALLOC, owner,
+			XFS_DATA_FORK, &bmap);
+}
+
+/* Schedule the deletion of an rmap for non-file data. */
+int
+xfs_rmap_free_extent(
+	struct xfs_mount	*mp,
+	struct xfs_defer_ops	*dfops,
+	xfs_agnumber_t		agno,
+	xfs_agblock_t		bno,
+	xfs_extlen_t		len,
+	__uint64_t		owner)
+{
+	struct xfs_bmbt_irec	bmap;
+
+	if (!xfs_rmap_update_is_needed(mp))
+		return 0;
+
+	bmap.br_startblock = XFS_AGB_TO_FSB(mp, agno, bno);
+	bmap.br_blockcount = len;
+	bmap.br_startoff = 0;
+	bmap.br_state = XFS_EXT_NORM;
+
+	return __xfs_rmap_add(mp, dfops, XFS_RMAP_FREE, owner,
+			XFS_DATA_FORK, &bmap);
+}