1 files changed, 967 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
new file mode 100644
index 000000000000..de65bb8bab04
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -0,0 +1,967 @@
+/*
+ * Copyright (c) 2000-2003,2005 Silicon Graphics, 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_ag.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_inode_item.h"
+#include "xfs_alloc.h"
+#include "xfs_btree.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_bmap.h"
+#include "xfs_error.h"
+#include "xfs_quota.h"
+#include "xfs_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_dinode.h"
+
+/*
+ * Determine the extent state.
+ */
+/* ARGSUSED */
+STATIC xfs_exntst_t
+xfs_extent_state(
+	xfs_filblks_t		blks,
+	int			extent_flag)
+{
+	if (extent_flag) {
+		ASSERT(blks != 0);	/* saved for DMIG */
+		return XFS_EXT_UNWRITTEN;
+	}
+	return XFS_EXT_NORM;
+}
+
+/*
+ * Convert on-disk form of btree root to in-memory form.
+ */
+void
+xfs_bmdr_to_bmbt(
+	struct xfs_inode	*ip,
+	xfs_bmdr_block_t	*dblock,
+	int			dblocklen,
+	struct xfs_btree_block	*rblock,
+	int			rblocklen)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	int			dmxr;
+	xfs_bmbt_key_t		*fkp;
+	__be64			*fpp;
+	xfs_bmbt_key_t		*tkp;
+	__be64			*tpp;
+
+	if (xfs_sb_version_hascrc(&mp->m_sb))
+		xfs_btree_init_block_int(mp, rblock, XFS_BUF_DADDR_NULL,
+				 XFS_BMAP_CRC_MAGIC, 0, 0, ip->i_ino,
+				 XFS_BTREE_LONG_PTRS | XFS_BTREE_CRC_BLOCKS);
+	else
+		xfs_btree_init_block_int(mp, rblock, XFS_BUF_DADDR_NULL,
+				 XFS_BMAP_MAGIC, 0, 0, ip->i_ino,
+				 XFS_BTREE_LONG_PTRS);
+
+	rblock->bb_level = dblock->bb_level;
+	ASSERT(be16_to_cpu(rblock->bb_level) > 0);
+	rblock->bb_numrecs = dblock->bb_numrecs;
+	dmxr = xfs_bmdr_maxrecs(dblocklen, 0);
+	fkp = XFS_BMDR_KEY_ADDR(dblock, 1);
+	tkp = XFS_BMBT_KEY_ADDR(mp, rblock, 1);
+	fpp = XFS_BMDR_PTR_ADDR(dblock, 1, dmxr);
+	tpp = XFS_BMAP_BROOT_PTR_ADDR(mp, rblock, 1, rblocklen);
+	dmxr = be16_to_cpu(dblock->bb_numrecs);
+	memcpy(tkp, fkp, sizeof(*fkp) * dmxr);
+	memcpy(tpp, fpp, sizeof(*fpp) * dmxr);
+}
+
+/*
+ * Convert a compressed bmap extent record to an uncompressed form.
+ * This code must be in sync with the routines xfs_bmbt_get_startoff,
+ * xfs_bmbt_get_startblock, xfs_bmbt_get_blockcount and xfs_bmbt_get_state.
+ */
+STATIC void
+__xfs_bmbt_get_all(
+		__uint64_t l0,
+		__uint64_t l1,
+		xfs_bmbt_irec_t *s)
+{
+	int	ext_flag;
+	xfs_exntst_t st;
+
+	ext_flag = (int)(l0 >> (64 - BMBT_EXNTFLAG_BITLEN));
+	s->br_startoff = ((xfs_fileoff_t)l0 &
+			   xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
+#if XFS_BIG_BLKNOS
+	s->br_startblock = (((xfs_fsblock_t)l0 & xfs_mask64lo(9)) << 43) |
+			   (((xfs_fsblock_t)l1) >> 21);
+#else
+#ifdef DEBUG
+	{
+		xfs_dfsbno_t	b;
+
+		b = (((xfs_dfsbno_t)l0 & xfs_mask64lo(9)) << 43) |
+		    (((xfs_dfsbno_t)l1) >> 21);
+		ASSERT((b >> 32) == 0 || isnulldstartblock(b));
+		s->br_startblock = (xfs_fsblock_t)b;
+	}
+#else	/* !DEBUG */
+	s->br_startblock = (xfs_fsblock_t)(((xfs_dfsbno_t)l1) >> 21);
+#endif	/* DEBUG */
+#endif	/* XFS_BIG_BLKNOS */
+	s->br_blockcount = (xfs_filblks_t)(l1 & xfs_mask64lo(21));
+	/* This is xfs_extent_state() in-line */
+	if (ext_flag) {
+		ASSERT(s->br_blockcount != 0);	/* saved for DMIG */
+		st = XFS_EXT_UNWRITTEN;
+	} else
+		st = XFS_EXT_NORM;
+	s->br_state = st;
+}
+
+void
+xfs_bmbt_get_all(
+	xfs_bmbt_rec_host_t *r,
+	xfs_bmbt_irec_t *s)
+{
+	__xfs_bmbt_get_all(r->l0, r->l1, s);
+}
+
+/*
+ * Extract the blockcount field from an in memory bmap extent record.
+ */
+xfs_filblks_t
+xfs_bmbt_get_blockcount(
+	xfs_bmbt_rec_host_t	*r)
+{
+	return (xfs_filblks_t)(r->l1 & xfs_mask64lo(21));
+}
+
+/*
+ * Extract the startblock field from an in memory bmap extent record.
+ */
+xfs_fsblock_t
+xfs_bmbt_get_startblock(
+	xfs_bmbt_rec_host_t	*r)
+{
+#if XFS_BIG_BLKNOS
+	return (((xfs_fsblock_t)r->l0 & xfs_mask64lo(9)) << 43) |
+	       (((xfs_fsblock_t)r->l1) >> 21);
+#else
+#ifdef DEBUG
+	xfs_dfsbno_t	b;
+
+	b = (((xfs_dfsbno_t)r->l0 & xfs_mask64lo(9)) << 43) |
+	    (((xfs_dfsbno_t)r->l1) >> 21);
+	ASSERT((b >> 32) == 0 || isnulldstartblock(b));
+	return (xfs_fsblock_t)b;
+#else	/* !DEBUG */
+	return (xfs_fsblock_t)(((xfs_dfsbno_t)r->l1) >> 21);
+#endif	/* DEBUG */
+#endif	/* XFS_BIG_BLKNOS */
+}
+
+/*
+ * Extract the startoff field from an in memory bmap extent record.
+ */
+xfs_fileoff_t
+xfs_bmbt_get_startoff(
+	xfs_bmbt_rec_host_t	*r)
+{
+	return ((xfs_fileoff_t)r->l0 &
+		 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
+}
+
+xfs_exntst_t
+xfs_bmbt_get_state(
+	xfs_bmbt_rec_host_t	*r)
+{
+	int	ext_flag;
+
+	ext_flag = (int)((r->l0) >> (64 - BMBT_EXNTFLAG_BITLEN));
+	return xfs_extent_state(xfs_bmbt_get_blockcount(r),
+				ext_flag);
+}
+
+/*
+ * Extract the blockcount field from an on disk bmap extent record.
+ */
+xfs_filblks_t
+xfs_bmbt_disk_get_blockcount(
+	xfs_bmbt_rec_t	*r)
+{
+	return (xfs_filblks_t)(be64_to_cpu(r->l1) & xfs_mask64lo(21));
+}
+
+/*
+ * Extract the startoff field from a disk format bmap extent record.
+ */
+xfs_fileoff_t
+xfs_bmbt_disk_get_startoff(
+	xfs_bmbt_rec_t	*r)
+{
+	return ((xfs_fileoff_t)be64_to_cpu(r->l0) &
+		 xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN)) >> 9;
+}
+
+
+/*
+ * Set all the fields in a bmap extent record from the arguments.
+ */
+void
+xfs_bmbt_set_allf(
+	xfs_bmbt_rec_host_t	*r,
+	xfs_fileoff_t		startoff,
+	xfs_fsblock_t		startblock,
+	xfs_filblks_t		blockcount,
+	xfs_exntst_t		state)
+{
+	int		extent_flag = (state == XFS_EXT_NORM) ? 0 : 1;
+
+	ASSERT(state == XFS_EXT_NORM || state == XFS_EXT_UNWRITTEN);
+	ASSERT((startoff & xfs_mask64hi(64-BMBT_STARTOFF_BITLEN)) == 0);
+	ASSERT((blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)) == 0);
+
+#if XFS_BIG_BLKNOS
+	ASSERT((startblock & xfs_mask64hi(64-BMBT_STARTBLOCK_BITLEN)) == 0);
+
+	r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
+		((xfs_bmbt_rec_base_t)startoff << 9) |
+		((xfs_bmbt_rec_base_t)startblock >> 43);
+	r->l1 = ((xfs_bmbt_rec_base_t)startblock << 21) |
+		((xfs_bmbt_rec_base_t)blockcount &
+		(xfs_bmbt_rec_base_t)xfs_mask64lo(21));
+#else	/* !XFS_BIG_BLKNOS */
+	if (isnullstartblock(startblock)) {
+		r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
+			((xfs_bmbt_rec_base_t)startoff << 9) |
+			 (xfs_bmbt_rec_base_t)xfs_mask64lo(9);
+		r->l1 = xfs_mask64hi(11) |
+			  ((xfs_bmbt_rec_base_t)startblock << 21) |
+			  ((xfs_bmbt_rec_base_t)blockcount &
+			   (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
+	} else {
+		r->l0 = ((xfs_bmbt_rec_base_t)extent_flag << 63) |
+			((xfs_bmbt_rec_base_t)startoff << 9);
+		r->l1 = ((xfs_bmbt_rec_base_t)startblock << 21) |
+			 ((xfs_bmbt_rec_base_t)blockcount &
+			 (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
+	}
+#endif	/* XFS_BIG_BLKNOS */
+}
+
+/*
+ * Set all the fields in a bmap extent record from the uncompressed form.
+ */
+void
+xfs_bmbt_set_all(
+	xfs_bmbt_rec_host_t *r,
+	xfs_bmbt_irec_t	*s)
+{
+	xfs_bmbt_set_allf(r, s->br_startoff, s->br_startblock,
+			     s->br_blockcount, s->br_state);
+}
+
+
+/*
+ * Set all the fields in a disk format bmap extent record from the arguments.
+ */
+void
+xfs_bmbt_disk_set_allf(
+	xfs_bmbt_rec_t		*r,
+	xfs_fileoff_t		startoff,
+	xfs_fsblock_t		startblock,
+	xfs_filblks_t		blockcount,
+	xfs_exntst_t		state)
+{
+	int			extent_flag = (state == XFS_EXT_NORM) ? 0 : 1;
+
+	ASSERT(state == XFS_EXT_NORM || state == XFS_EXT_UNWRITTEN);
+	ASSERT((startoff & xfs_mask64hi(64-BMBT_STARTOFF_BITLEN)) == 0);
+	ASSERT((blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)) == 0);
+
+#if XFS_BIG_BLKNOS
+	ASSERT((startblock & xfs_mask64hi(64-BMBT_STARTBLOCK_BITLEN)) == 0);
+
+	r->l0 = cpu_to_be64(
+		((xfs_bmbt_rec_base_t)extent_flag << 63) |
+		 ((xfs_bmbt_rec_base_t)startoff << 9) |
+		 ((xfs_bmbt_rec_base_t)startblock >> 43));
+	r->l1 = cpu_to_be64(
+		((xfs_bmbt_rec_base_t)startblock << 21) |
+		 ((xfs_bmbt_rec_base_t)blockcount &
+		  (xfs_bmbt_rec_base_t)xfs_mask64lo(21)));
+#else	/* !XFS_BIG_BLKNOS */
+	if (isnullstartblock(startblock)) {
+		r->l0 = cpu_to_be64(
+			((xfs_bmbt_rec_base_t)extent_flag << 63) |
+			 ((xfs_bmbt_rec_base_t)startoff << 9) |
+			  (xfs_bmbt_rec_base_t)xfs_mask64lo(9));
+		r->l1 = cpu_to_be64(xfs_mask64hi(11) |
+			  ((xfs_bmbt_rec_base_t)startblock << 21) |
+			  ((xfs_bmbt_rec_base_t)blockcount &
+			   (xfs_bmbt_rec_base_t)xfs_mask64lo(21)));
+	} else {
+		r->l0 = cpu_to_be64(
+			((xfs_bmbt_rec_base_t)extent_flag << 63) |
+			 ((xfs_bmbt_rec_base_t)startoff << 9));
+		r->l1 = cpu_to_be64(
+			((xfs_bmbt_rec_base_t)startblock << 21) |
+			 ((xfs_bmbt_rec_base_t)blockcount &
+			  (xfs_bmbt_rec_base_t)xfs_mask64lo(21)));
+	}
+#endif	/* XFS_BIG_BLKNOS */
+}
+
+/*
+ * Set all the fields in a bmap extent record from the uncompressed form.
+ */
+STATIC void
+xfs_bmbt_disk_set_all(
+	xfs_bmbt_rec_t	*r,
+	xfs_bmbt_irec_t *s)
+{
+	xfs_bmbt_disk_set_allf(r, s->br_startoff, s->br_startblock,
+				  s->br_blockcount, s->br_state);
+}
+
+/*
+ * Set the blockcount field in a bmap extent record.
+ */
+void
+xfs_bmbt_set_blockcount(
+	xfs_bmbt_rec_host_t *r,
+	xfs_filblks_t	v)
+{
+	ASSERT((v & xfs_mask64hi(43)) == 0);
+	r->l1 = (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64hi(43)) |
+		  (xfs_bmbt_rec_base_t)(v & xfs_mask64lo(21));
+}
+
+/*
+ * Set the startblock field in a bmap extent record.
+ */
+void
+xfs_bmbt_set_startblock(
+	xfs_bmbt_rec_host_t *r,
+	xfs_fsblock_t	v)
+{
+#if XFS_BIG_BLKNOS
+	ASSERT((v & xfs_mask64hi(12)) == 0);
+	r->l0 = (r->l0 & (xfs_bmbt_rec_base_t)xfs_mask64hi(55)) |
+		  (xfs_bmbt_rec_base_t)(v >> 43);
+	r->l1 = (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64lo(21)) |
+		  (xfs_bmbt_rec_base_t)(v << 21);
+#else	/* !XFS_BIG_BLKNOS */
+	if (isnullstartblock(v)) {
+		r->l0 |= (xfs_bmbt_rec_base_t)xfs_mask64lo(9);
+		r->l1 = (xfs_bmbt_rec_base_t)xfs_mask64hi(11) |
+			  ((xfs_bmbt_rec_base_t)v << 21) |
+			  (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
+	} else {
+		r->l0 &= ~(xfs_bmbt_rec_base_t)xfs_mask64lo(9);
+		r->l1 = ((xfs_bmbt_rec_base_t)v << 21) |
+			  (r->l1 & (xfs_bmbt_rec_base_t)xfs_mask64lo(21));
+	}
+#endif	/* XFS_BIG_BLKNOS */
+}
+
+/*
+ * Set the startoff field in a bmap extent record.
+ */
+void
+xfs_bmbt_set_startoff(
+	xfs_bmbt_rec_host_t *r,
+	xfs_fileoff_t	v)
+{
+	ASSERT((v & xfs_mask64hi(9)) == 0);
+	r->l0 = (r->l0 & (xfs_bmbt_rec_base_t) xfs_mask64hi(1)) |
+		((xfs_bmbt_rec_base_t)v << 9) |
+		  (r->l0 & (xfs_bmbt_rec_base_t)xfs_mask64lo(9));
+}
+
+/*
+ * Set the extent state field in a bmap extent record.
+ */
+void
+xfs_bmbt_set_state(
+	xfs_bmbt_rec_host_t *r,
+	xfs_exntst_t	v)
+{
+	ASSERT(v == XFS_EXT_NORM || v == XFS_EXT_UNWRITTEN);
+	if (v == XFS_EXT_NORM)
+		r->l0 &= xfs_mask64lo(64 - BMBT_EXNTFLAG_BITLEN);
+	else
+		r->l0 |= xfs_mask64hi(BMBT_EXNTFLAG_BITLEN);
+}
+
+/*
+ * Convert in-memory form of btree root to on-disk form.
+ */
+void
+xfs_bmbt_to_bmdr(
+	struct xfs_mount	*mp,
+	struct xfs_btree_block	*rblock,
+	int			rblocklen,
+	xfs_bmdr_block_t	*dblock,
+	int			dblocklen)
+{
+	int			dmxr;
+	xfs_bmbt_key_t		*fkp;
+	__be64			*fpp;
+	xfs_bmbt_key_t		*tkp;
+	__be64			*tpp;
+
+	if (xfs_sb_version_hascrc(&mp->m_sb)) {
+		ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_CRC_MAGIC));
+		ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid));
+		ASSERT(rblock->bb_u.l.bb_blkno ==
+		       cpu_to_be64(XFS_BUF_DADDR_NULL));
+	} else
+		ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_MAGIC));
+	ASSERT(rblock->bb_u.l.bb_leftsib == cpu_to_be64(NULLDFSBNO));
+	ASSERT(rblock->bb_u.l.bb_rightsib == cpu_to_be64(NULLDFSBNO));
+	ASSERT(rblock->bb_level != 0);
+	dblock->bb_level = rblock->bb_level;
+	dblock->bb_numrecs = rblock->bb_numrecs;
+	dmxr = xfs_bmdr_maxrecs(dblocklen, 0);
+	fkp = XFS_BMBT_KEY_ADDR(mp, rblock, 1);
+	tkp = XFS_BMDR_KEY_ADDR(dblock, 1);
+	fpp = XFS_BMAP_BROOT_PTR_ADDR(mp, rblock, 1, rblocklen);
+	tpp = XFS_BMDR_PTR_ADDR(dblock, 1, dmxr);
+	dmxr = be16_to_cpu(dblock->bb_numrecs);
+	memcpy(tkp, fkp, sizeof(*fkp) * dmxr);
+	memcpy(tpp, fpp, sizeof(*fpp) * dmxr);
+}
+
+/*
+ * Check extent records, which have just been read, for
+ * any bit in the extent flag field. ASSERT on debug
+ * kernels, as this condition should not occur.
+ * Return an error condition (1) if any flags found,
+ * otherwise return 0.
+ */
+
+int
+xfs_check_nostate_extents(
+	xfs_ifork_t		*ifp,
+	xfs_extnum_t		idx,
+	xfs_extnum_t		num)
+{
+	for (; num > 0; num--, idx++) {
+		xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, idx);
+		if ((ep->l0 >>
+		     (64 - BMBT_EXNTFLAG_BITLEN)) != 0) {
+			ASSERT(0);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+
+STATIC struct xfs_btree_cur *
+xfs_bmbt_dup_cursor(
+	struct xfs_btree_cur	*cur)
+{
+	struct xfs_btree_cur	*new;
+
+	new = xfs_bmbt_init_cursor(cur->bc_mp, cur->bc_tp,
+			cur->bc_private.b.ip, cur->bc_private.b.whichfork);
+
+	/*
+	 * Copy the firstblock, flist, and flags values,
+	 * since init cursor doesn't get them.
+	 */
+	new->bc_private.b.firstblock = cur->bc_private.b.firstblock;
+	new->bc_private.b.flist = cur->bc_private.b.flist;
+	new->bc_private.b.flags = cur->bc_private.b.flags;
+
+	return new;
+}
+
+STATIC void
+xfs_bmbt_update_cursor(
+	struct xfs_btree_cur	*src,
+	struct xfs_btree_cur	*dst)
+{
+	ASSERT((dst->bc_private.b.firstblock != NULLFSBLOCK) ||
+	       (dst->bc_private.b.ip->i_d.di_flags & XFS_DIFLAG_REALTIME));
+	ASSERT(dst->bc_private.b.flist == src->bc_private.b.flist);
+
+	dst->bc_private.b.allocated += src->bc_private.b.allocated;
+	dst->bc_private.b.firstblock = src->bc_private.b.firstblock;
+
+	src->bc_private.b.allocated = 0;
+}
+
+STATIC int
+xfs_bmbt_alloc_block(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*start,
+	union xfs_btree_ptr	*new,
+	int			*stat)
+{
+	xfs_alloc_arg_t		args;		/* block allocation args */
+	int			error;		/* error return value */
+
+	memset(&args, 0, sizeof(args));
+	args.tp = cur->bc_tp;
+	args.mp = cur->bc_mp;
+	args.fsbno = cur->bc_private.b.firstblock;
+	args.firstblock = args.fsbno;
+
+	if (args.fsbno == NULLFSBLOCK) {
+		args.fsbno = be64_to_cpu(start->l);
+		args.type = XFS_ALLOCTYPE_START_BNO;
+		/*
+		 * Make sure there is sufficient room left in the AG to
+		 * complete a full tree split for an extent insert.  If
+		 * we are converting the middle part of an extent then
+		 * we may need space for two tree splits.
+		 *
+		 * We are relying on the caller to make the correct block
+		 * reservation for this operation to succeed.  If the
+		 * reservation amount is insufficient then we may fail a
+		 * block allocation here and corrupt the filesystem.
+		 */
+		args.minleft = xfs_trans_get_block_res(args.tp);
+	} else if (cur->bc_private.b.flist->xbf_low) {
+		args.type = XFS_ALLOCTYPE_START_BNO;
+	} else {
+		args.type = XFS_ALLOCTYPE_NEAR_BNO;
+	}
+
+	args.minlen = args.maxlen = args.prod = 1;
+	args.wasdel = cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL;
+	if (!args.wasdel && xfs_trans_get_block_res(args.tp) == 0) {
+		error = ENOSPC;
+		goto error0;
+	}
+	error = xfs_alloc_vextent(&args);
+	if (error)
+		goto error0;
+
+	if (args.fsbno == NULLFSBLOCK && args.minleft) {
+		/*
+		 * Could not find an AG with enough free space to satisfy
+		 * a full btree split.  Try again without minleft and if
+		 * successful activate the lowspace algorithm.
+		 */
+		args.fsbno = 0;
+		args.type = XFS_ALLOCTYPE_FIRST_AG;
+		args.minleft = 0;
+		error = xfs_alloc_vextent(&args);
+		if (error)
+			goto error0;
+		cur->bc_private.b.flist->xbf_low = 1;
+	}
+	if (args.fsbno == NULLFSBLOCK) {
+		XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+		*stat = 0;
+		return 0;
+	}
+	ASSERT(args.len == 1);
+	cur->bc_private.b.firstblock = args.fsbno;
+	cur->bc_private.b.allocated++;
+	cur->bc_private.b.ip->i_d.di_nblocks++;
+	xfs_trans_log_inode(args.tp, cur->bc_private.b.ip, XFS_ILOG_CORE);
+	xfs_trans_mod_dquot_byino(args.tp, cur->bc_private.b.ip,
+			XFS_TRANS_DQ_BCOUNT, 1L);
+
+	new->l = cpu_to_be64(args.fsbno);
+
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+	*stat = 1;
+	return 0;
+
+ error0:
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+	return error;
+}
+
+STATIC int
+xfs_bmbt_free_block(
+	struct xfs_btree_cur	*cur,
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = cur->bc_mp;
+	struct xfs_inode	*ip = cur->bc_private.b.ip;
+	struct xfs_trans	*tp = cur->bc_tp;
+	xfs_fsblock_t		fsbno = XFS_DADDR_TO_FSB(mp, XFS_BUF_ADDR(bp));
+
+	xfs_bmap_add_free(fsbno, 1, cur->bc_private.b.flist, mp);
+	ip->i_d.di_nblocks--;
+
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
+	xfs_trans_binval(tp, bp);
+	return 0;
+}
+
+STATIC int
+xfs_bmbt_get_minrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level == cur->bc_nlevels - 1) {
+		struct xfs_ifork	*ifp;
+
+		ifp = XFS_IFORK_PTR(cur->bc_private.b.ip,
+				    cur->bc_private.b.whichfork);
+
+		return xfs_bmbt_maxrecs(cur->bc_mp,
+					ifp->if_broot_bytes, level == 0) / 2;
+	}
+
+	return cur->bc_mp->m_bmap_dmnr[level != 0];
+}
+
+int
+xfs_bmbt_get_maxrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level == cur->bc_nlevels - 1) {
+		struct xfs_ifork	*ifp;
+
+		ifp = XFS_IFORK_PTR(cur->bc_private.b.ip,
+				    cur->bc_private.b.whichfork);
+
+		return xfs_bmbt_maxrecs(cur->bc_mp,
+					ifp->if_broot_bytes, level == 0);
+	}
+
+	return cur->bc_mp->m_bmap_dmxr[level != 0];
+
+}
+
+/*
+ * Get the maximum records we could store in the on-disk format.
+ *
+ * For non-root nodes this is equivalent to xfs_bmbt_get_maxrecs, but
+ * for the root node this checks the available space in the dinode fork
+ * so that we can resize the in-memory buffer to match it.  After a
+ * resize to the maximum size this function returns the same value
+ * as xfs_bmbt_get_maxrecs for the root node, too.
+ */
+STATIC int
+xfs_bmbt_get_dmaxrecs(
+	struct xfs_btree_cur	*cur,
+	int			level)
+{
+	if (level != cur->bc_nlevels - 1)
+		return cur->bc_mp->m_bmap_dmxr[level != 0];
+	return xfs_bmdr_maxrecs(cur->bc_private.b.forksize, level == 0);
+}
+
+STATIC void
+xfs_bmbt_init_key_from_rec(
+	union xfs_btree_key	*key,
+	union xfs_btree_rec	*rec)
+{
+	key->bmbt.br_startoff =
+		cpu_to_be64(xfs_bmbt_disk_get_startoff(&rec->bmbt));
+}
+
+STATIC void
+xfs_bmbt_init_rec_from_key(
+	union xfs_btree_key	*key,
+	union xfs_btree_rec	*rec)
+{
+	ASSERT(key->bmbt.br_startoff != 0);
+
+	xfs_bmbt_disk_set_allf(&rec->bmbt, be64_to_cpu(key->bmbt.br_startoff),
+			       0, 0, XFS_EXT_NORM);
+}
+
+STATIC void
+xfs_bmbt_init_rec_from_cur(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_rec	*rec)
+{
+	xfs_bmbt_disk_set_all(&rec->bmbt, &cur->bc_rec.b);
+}
+
+STATIC void
+xfs_bmbt_init_ptr_from_cur(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_ptr	*ptr)
+{
+	ptr->l = 0;
+}
+
+STATIC __int64_t
+xfs_bmbt_key_diff(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_key	*key)
+{
+	return (__int64_t)be64_to_cpu(key->bmbt.br_startoff) -
+				      cur->bc_rec.b.br_startoff;
+}
+
+static bool
+xfs_bmbt_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
+	unsigned int		level;
+
+	switch (block->bb_magic) {
+	case cpu_to_be32(XFS_BMAP_CRC_MAGIC):
+		if (!xfs_sb_version_hascrc(&mp->m_sb))
+			return false;
+		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid))
+			return false;
+		if (be64_to_cpu(block->bb_u.l.bb_blkno) != bp->b_bn)
+			return false;
+		/*
+		 * XXX: need a better way of verifying the owner here. Right now
+		 * just make sure there has been one set.
+		 */
+		if (be64_to_cpu(block->bb_u.l.bb_owner) == 0)
+			return false;
+		/* fall through */
+	case cpu_to_be32(XFS_BMAP_MAGIC):
+		break;
+	default:
+		return false;
+	}
+
+	/*
+	 * numrecs and level verification.
+	 *
+	 * We don't know what fork we belong to, so just verify that the level
+	 * is less than the maximum of the two. Later checks will be more
+	 * precise.
+	 */
+	level = be16_to_cpu(block->bb_level);
+	if (level > max(mp->m_bm_maxlevels[0], mp->m_bm_maxlevels[1]))
+		return false;
+	if (be16_to_cpu(block->bb_numrecs) > mp->m_bmap_dmxr[level != 0])
+		return false;
+
+	/* sibling pointer verification */
+	if (!block->bb_u.l.bb_leftsib ||
+	    (block->bb_u.l.bb_leftsib != cpu_to_be64(NULLDFSBNO) &&
+	     !XFS_FSB_SANITY_CHECK(mp, be64_to_cpu(block->bb_u.l.bb_leftsib))))
+		return false;
+	if (!block->bb_u.l.bb_rightsib ||
+	    (block->bb_u.l.bb_rightsib != cpu_to_be64(NULLDFSBNO) &&
+	     !XFS_FSB_SANITY_CHECK(mp, be64_to_cpu(block->bb_u.l.bb_rightsib))))
+		return false;
+
+	return true;
+}
+
+static void
+xfs_bmbt_read_verify(
+	struct xfs_buf	*bp)
+{
+	if (!xfs_btree_lblock_verify_crc(bp))
+		xfs_buf_ioerror(bp, EFSBADCRC);
+	else if (!xfs_bmbt_verify(bp))
+		xfs_buf_ioerror(bp, EFSCORRUPTED);
+
+	if (bp->b_error) {
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+		xfs_verifier_error(bp);
+	}
+}
+
+static void
+xfs_bmbt_write_verify(
+	struct xfs_buf	*bp)
+{
+	if (!xfs_bmbt_verify(bp)) {
+		trace_xfs_btree_corrupt(bp, _RET_IP_);
+		xfs_buf_ioerror(bp, EFSCORRUPTED);
+		xfs_verifier_error(bp);
+		return;
+	}
+	xfs_btree_lblock_calc_crc(bp);
+}
+
+const struct xfs_buf_ops xfs_bmbt_buf_ops = {
+	.verify_read = xfs_bmbt_read_verify,
+	.verify_write = xfs_bmbt_write_verify,
+};
+
+
+#if defined(DEBUG) || defined(XFS_WARN)
+STATIC int
+xfs_bmbt_keys_inorder(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_key	*k1,
+	union xfs_btree_key	*k2)
+{
+	return be64_to_cpu(k1->bmbt.br_startoff) <
+		be64_to_cpu(k2->bmbt.br_startoff);
+}
+
+STATIC int
+xfs_bmbt_recs_inorder(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_rec	*r1,
+	union xfs_btree_rec	*r2)
+{
+	return xfs_bmbt_disk_get_startoff(&r1->bmbt) +
+		xfs_bmbt_disk_get_blockcount(&r1->bmbt) <=
+		xfs_bmbt_disk_get_startoff(&r2->bmbt);
+}
+#endif	/* DEBUG */
+
+static const struct xfs_btree_ops xfs_bmbt_ops = {
+	.rec_len		= sizeof(xfs_bmbt_rec_t),
+	.key_len		= sizeof(xfs_bmbt_key_t),
+
+	.dup_cursor		= xfs_bmbt_dup_cursor,
+	.update_cursor		= xfs_bmbt_update_cursor,
+	.alloc_block		= xfs_bmbt_alloc_block,
+	.free_block		= xfs_bmbt_free_block,
+	.get_maxrecs		= xfs_bmbt_get_maxrecs,
+	.get_minrecs		= xfs_bmbt_get_minrecs,
+	.get_dmaxrecs		= xfs_bmbt_get_dmaxrecs,
+	.init_key_from_rec	= xfs_bmbt_init_key_from_rec,
+	.init_rec_from_key	= xfs_bmbt_init_rec_from_key,
+	.init_rec_from_cur	= xfs_bmbt_init_rec_from_cur,
+	.init_ptr_from_cur	= xfs_bmbt_init_ptr_from_cur,
+	.key_diff		= xfs_bmbt_key_diff,
+	.buf_ops		= &xfs_bmbt_buf_ops,
+#if defined(DEBUG) || defined(XFS_WARN)
+	.keys_inorder		= xfs_bmbt_keys_inorder,
+	.recs_inorder		= xfs_bmbt_recs_inorder,
+#endif
+};
+
+/*
+ * Allocate a new bmap btree cursor.
+ */
+struct xfs_btree_cur *				/* new bmap btree cursor */
+xfs_bmbt_init_cursor(
+	struct xfs_mount	*mp,		/* file system mount point */
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* inode owning the btree */
+	int			whichfork)	/* data or attr fork */
+{
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_btree_cur	*cur;
+
+	cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_SLEEP);
+
+	cur->bc_tp = tp;
+	cur->bc_mp = mp;
+	cur->bc_nlevels = be16_to_cpu(ifp->if_broot->bb_level) + 1;
+	cur->bc_btnum = XFS_BTNUM_BMAP;
+	cur->bc_blocklog = mp->m_sb.sb_blocklog;
+
+	cur->bc_ops = &xfs_bmbt_ops;
+	cur->bc_flags = XFS_BTREE_LONG_PTRS | XFS_BTREE_ROOT_IN_INODE;
+	if (xfs_sb_version_hascrc(&mp->m_sb))
+		cur->bc_flags |= XFS_BTREE_CRC_BLOCKS;
+
+	cur->bc_private.b.forksize = XFS_IFORK_SIZE(ip, whichfork);
+	cur->bc_private.b.ip = ip;
+	cur->bc_private.b.firstblock = NULLFSBLOCK;
+	cur->bc_private.b.flist = NULL;
+	cur->bc_private.b.allocated = 0;
+	cur->bc_private.b.flags = 0;
+	cur->bc_private.b.whichfork = whichfork;
+
+	return cur;
+}
+
+/*
+ * Calculate number of records in a bmap btree block.
+ */
+int
+xfs_bmbt_maxrecs(
+	struct xfs_mount	*mp,
+	int			blocklen,
+	int			leaf)
+{
+	blocklen -= XFS_BMBT_BLOCK_LEN(mp);
+
+	if (leaf)
+		return blocklen / sizeof(xfs_bmbt_rec_t);
+	return blocklen / (sizeof(xfs_bmbt_key_t) + sizeof(xfs_bmbt_ptr_t));
+}
+
+/*
+ * Calculate number of records in a bmap btree inode root.
+ */
+int
+xfs_bmdr_maxrecs(
+	int			blocklen,
+	int			leaf)
+{
+	blocklen -= sizeof(xfs_bmdr_block_t);
+
+	if (leaf)
+		return blocklen / sizeof(xfs_bmdr_rec_t);
+	return blocklen / (sizeof(xfs_bmdr_key_t) + sizeof(xfs_bmdr_ptr_t));
+}
+
+/*
+ * Change the owner of a btree format fork fo the inode passed in. Change it to
+ * the owner of that is passed in so that we can change owners before or after
+ * we switch forks between inodes. The operation that the caller is doing will
+ * determine whether is needs to change owner before or after the switch.
+ *
+ * For demand paged transactional modification, the fork switch should be done
+ * after reading in all the blocks, modifying them and pinning them in the
+ * transaction. For modification when the buffers are already pinned in memory,
+ * the fork switch can be done before changing the owner as we won't need to
+ * validate the owner until the btree buffers are unpinned and writes can occur
+ * again.
+ *
+ * For recovery based ownership change, there is no transactional context and
+ * so a buffer list must be supplied so that we can record the buffers that we
+ * modified for the caller to issue IO on.
+ */
+int
+xfs_bmbt_change_owner(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	xfs_ino_t		new_owner,
+	struct list_head	*buffer_list)
+{
+	struct xfs_btree_cur	*cur;
+	int			error;
+
+	ASSERT(tp || buffer_list);
+	ASSERT(!(tp && buffer_list));
+	if (whichfork == XFS_DATA_FORK)
+		ASSERT(ip->i_d.di_format == XFS_DINODE_FMT_BTREE);
+	else
+		ASSERT(ip->i_d.di_aformat == XFS_DINODE_FMT_BTREE);
+
+	cur = xfs_bmbt_init_cursor(ip->i_mount, tp, ip, whichfork);
+	if (!cur)
+		return ENOMEM;
+
+	error = xfs_btree_change_owner(cur, new_owner, buffer_list);
+	xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
+	return error;
+}