Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 6240 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
new file mode 100644
index 0000000000..30c931b388
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -0,0 +1,6240 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2006 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#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_dir2.h"
+#include "xfs_inode.h"
+#include "xfs_btree.h"
+#include "xfs_trans.h"
+#include "xfs_alloc.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_rtalloc.h"
+#include "xfs_errortag.h"
+#include "xfs_error.h"
+#include "xfs_quota.h"
+#include "xfs_trans_space.h"
+#include "xfs_buf_item.h"
+#include "xfs_trace.h"
+#include "xfs_attr_leaf.h"
+#include "xfs_filestream.h"
+#include "xfs_rmap.h"
+#include "xfs_ag.h"
+#include "xfs_ag_resv.h"
+#include "xfs_refcount.h"
+#include "xfs_icache.h"
+#include "xfs_iomap.h"
+
+struct kmem_cache		*xfs_bmap_intent_cache;
+
+/*
+ * Miscellaneous helper functions
+ */
+
+/*
+ * Compute and fill in the value of the maximum depth of a bmap btree
+ * in this filesystem.  Done once, during mount.
+ */
+void
+xfs_bmap_compute_maxlevels(
+	xfs_mount_t	*mp,		/* file system mount structure */
+	int		whichfork)	/* data or attr fork */
+{
+	uint64_t	maxblocks;	/* max blocks at this level */
+	xfs_extnum_t	maxleafents;	/* max leaf entries possible */
+	int		level;		/* btree level */
+	int		maxrootrecs;	/* max records in root block */
+	int		minleafrecs;	/* min records in leaf block */
+	int		minnoderecs;	/* min records in node block */
+	int		sz;		/* root block size */
+
+	/*
+	 * The maximum number of extents in a fork, hence the maximum number of
+	 * leaf entries, is controlled by the size of the on-disk extent count.
+	 *
+	 * Note that we can no longer assume that if we are in ATTR1 that the
+	 * fork offset of all the inodes will be
+	 * (xfs_default_attroffset(ip) >> 3) because we could have mounted with
+	 * ATTR2 and then mounted back with ATTR1, keeping the i_forkoff's fixed
+	 * but probably at various positions. Therefore, for both ATTR1 and
+	 * ATTR2 we have to assume the worst case scenario of a minimum size
+	 * available.
+	 */
+	maxleafents = xfs_iext_max_nextents(xfs_has_large_extent_counts(mp),
+				whichfork);
+	if (whichfork == XFS_DATA_FORK)
+		sz = XFS_BMDR_SPACE_CALC(MINDBTPTRS);
+	else
+		sz = XFS_BMDR_SPACE_CALC(MINABTPTRS);
+
+	maxrootrecs = xfs_bmdr_maxrecs(sz, 0);
+	minleafrecs = mp->m_bmap_dmnr[0];
+	minnoderecs = mp->m_bmap_dmnr[1];
+	maxblocks = howmany_64(maxleafents, minleafrecs);
+	for (level = 1; maxblocks > 1; level++) {
+		if (maxblocks <= maxrootrecs)
+			maxblocks = 1;
+		else
+			maxblocks = howmany_64(maxblocks, minnoderecs);
+	}
+	mp->m_bm_maxlevels[whichfork] = level;
+	ASSERT(mp->m_bm_maxlevels[whichfork] <= xfs_bmbt_maxlevels_ondisk());
+}
+
+unsigned int
+xfs_bmap_compute_attr_offset(
+	struct xfs_mount	*mp)
+{
+	if (mp->m_sb.sb_inodesize == 256)
+		return XFS_LITINO(mp) - XFS_BMDR_SPACE_CALC(MINABTPTRS);
+	return XFS_BMDR_SPACE_CALC(6 * MINABTPTRS);
+}
+
+STATIC int				/* error */
+xfs_bmbt_lookup_eq(
+	struct xfs_btree_cur	*cur,
+	struct xfs_bmbt_irec	*irec,
+	int			*stat)	/* success/failure */
+{
+	cur->bc_rec.b = *irec;
+	return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
+}
+
+STATIC int				/* error */
+xfs_bmbt_lookup_first(
+	struct xfs_btree_cur	*cur,
+	int			*stat)	/* success/failure */
+{
+	cur->bc_rec.b.br_startoff = 0;
+	cur->bc_rec.b.br_startblock = 0;
+	cur->bc_rec.b.br_blockcount = 0;
+	return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
+}
+
+/*
+ * Check if the inode needs to be converted to btree format.
+ */
+static inline bool xfs_bmap_needs_btree(struct xfs_inode *ip, int whichfork)
+{
+	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
+
+	return whichfork != XFS_COW_FORK &&
+		ifp->if_format == XFS_DINODE_FMT_EXTENTS &&
+		ifp->if_nextents > XFS_IFORK_MAXEXT(ip, whichfork);
+}
+
+/*
+ * Check if the inode should be converted to extent format.
+ */
+static inline bool xfs_bmap_wants_extents(struct xfs_inode *ip, int whichfork)
+{
+	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
+
+	return whichfork != XFS_COW_FORK &&
+		ifp->if_format == XFS_DINODE_FMT_BTREE &&
+		ifp->if_nextents <= XFS_IFORK_MAXEXT(ip, whichfork);
+}
+
+/*
+ * Update the record referred to by cur to the value given by irec
+ * This either works (return 0) or gets an EFSCORRUPTED error.
+ */
+STATIC int
+xfs_bmbt_update(
+	struct xfs_btree_cur	*cur,
+	struct xfs_bmbt_irec	*irec)
+{
+	union xfs_btree_rec	rec;
+
+	xfs_bmbt_disk_set_all(&rec.bmbt, irec);
+	return xfs_btree_update(cur, &rec);
+}
+
+/*
+ * Compute the worst-case number of indirect blocks that will be used
+ * for ip's delayed extent of length "len".
+ */
+STATIC xfs_filblks_t
+xfs_bmap_worst_indlen(
+	xfs_inode_t	*ip,		/* incore inode pointer */
+	xfs_filblks_t	len)		/* delayed extent length */
+{
+	int		level;		/* btree level number */
+	int		maxrecs;	/* maximum record count at this level */
+	xfs_mount_t	*mp;		/* mount structure */
+	xfs_filblks_t	rval;		/* return value */
+
+	mp = ip->i_mount;
+	maxrecs = mp->m_bmap_dmxr[0];
+	for (level = 0, rval = 0;
+	     level < XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK);
+	     level++) {
+		len += maxrecs - 1;
+		do_div(len, maxrecs);
+		rval += len;
+		if (len == 1)
+			return rval + XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK) -
+				level - 1;
+		if (level == 0)
+			maxrecs = mp->m_bmap_dmxr[1];
+	}
+	return rval;
+}
+
+/*
+ * Calculate the default attribute fork offset for newly created inodes.
+ */
+uint
+xfs_default_attroffset(
+	struct xfs_inode	*ip)
+{
+	if (ip->i_df.if_format == XFS_DINODE_FMT_DEV)
+		return roundup(sizeof(xfs_dev_t), 8);
+	return M_IGEO(ip->i_mount)->attr_fork_offset;
+}
+
+/*
+ * Helper routine to reset inode i_forkoff field when switching attribute fork
+ * from local to extent format - we reset it where possible to make space
+ * available for inline data fork extents.
+ */
+STATIC void
+xfs_bmap_forkoff_reset(
+	xfs_inode_t	*ip,
+	int		whichfork)
+{
+	if (whichfork == XFS_ATTR_FORK &&
+	    ip->i_df.if_format != XFS_DINODE_FMT_DEV &&
+	    ip->i_df.if_format != XFS_DINODE_FMT_BTREE) {
+		uint	dfl_forkoff = xfs_default_attroffset(ip) >> 3;
+
+		if (dfl_forkoff > ip->i_forkoff)
+			ip->i_forkoff = dfl_forkoff;
+	}
+}
+
+#ifdef DEBUG
+STATIC struct xfs_buf *
+xfs_bmap_get_bp(
+	struct xfs_btree_cur	*cur,
+	xfs_fsblock_t		bno)
+{
+	struct xfs_log_item	*lip;
+	int			i;
+
+	if (!cur)
+		return NULL;
+
+	for (i = 0; i < cur->bc_maxlevels; i++) {
+		if (!cur->bc_levels[i].bp)
+			break;
+		if (xfs_buf_daddr(cur->bc_levels[i].bp) == bno)
+			return cur->bc_levels[i].bp;
+	}
+
+	/* Chase down all the log items to see if the bp is there */
+	list_for_each_entry(lip, &cur->bc_tp->t_items, li_trans) {
+		struct xfs_buf_log_item	*bip = (struct xfs_buf_log_item *)lip;
+
+		if (bip->bli_item.li_type == XFS_LI_BUF &&
+		    xfs_buf_daddr(bip->bli_buf) == bno)
+			return bip->bli_buf;
+	}
+
+	return NULL;
+}
+
+STATIC void
+xfs_check_block(
+	struct xfs_btree_block	*block,
+	xfs_mount_t		*mp,
+	int			root,
+	short			sz)
+{
+	int			i, j, dmxr;
+	__be64			*pp, *thispa;	/* pointer to block address */
+	xfs_bmbt_key_t		*prevp, *keyp;
+
+	ASSERT(be16_to_cpu(block->bb_level) > 0);
+
+	prevp = NULL;
+	for( i = 1; i <= xfs_btree_get_numrecs(block); i++) {
+		dmxr = mp->m_bmap_dmxr[0];
+		keyp = XFS_BMBT_KEY_ADDR(mp, block, i);
+
+		if (prevp) {
+			ASSERT(be64_to_cpu(prevp->br_startoff) <
+			       be64_to_cpu(keyp->br_startoff));
+		}
+		prevp = keyp;
+
+		/*
+		 * Compare the block numbers to see if there are dups.
+		 */
+		if (root)
+			pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, i, sz);
+		else
+			pp = XFS_BMBT_PTR_ADDR(mp, block, i, dmxr);
+
+		for (j = i+1; j <= be16_to_cpu(block->bb_numrecs); j++) {
+			if (root)
+				thispa = XFS_BMAP_BROOT_PTR_ADDR(mp, block, j, sz);
+			else
+				thispa = XFS_BMBT_PTR_ADDR(mp, block, j, dmxr);
+			if (*thispa == *pp) {
+				xfs_warn(mp, "%s: thispa(%d) == pp(%d) %lld",
+					__func__, j, i,
+					(unsigned long long)be64_to_cpu(*thispa));
+				xfs_err(mp, "%s: ptrs are equal in node\n",
+					__func__);
+				xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+			}
+		}
+	}
+}
+
+/*
+ * Check that the extents for the inode ip are in the right order in all
+ * btree leaves. THis becomes prohibitively expensive for large extent count
+ * files, so don't bother with inodes that have more than 10,000 extents in
+ * them. The btree record ordering checks will still be done, so for such large
+ * bmapbt constructs that is going to catch most corruptions.
+ */
+STATIC void
+xfs_bmap_check_leaf_extents(
+	struct xfs_btree_cur	*cur,	/* btree cursor or null */
+	xfs_inode_t		*ip,		/* incore inode pointer */
+	int			whichfork)	/* data or attr fork */
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_btree_block	*block;	/* current btree block */
+	xfs_fsblock_t		bno;	/* block # of "block" */
+	struct xfs_buf		*bp;	/* buffer for "block" */
+	int			error;	/* error return value */
+	xfs_extnum_t		i=0, j;	/* index into the extents list */
+	int			level;	/* btree level, for checking */
+	__be64			*pp;	/* pointer to block address */
+	xfs_bmbt_rec_t		*ep;	/* pointer to current extent */
+	xfs_bmbt_rec_t		last = {0, 0}; /* last extent in prev block */
+	xfs_bmbt_rec_t		*nextp;	/* pointer to next extent */
+	int			bp_release = 0;
+
+	if (ifp->if_format != XFS_DINODE_FMT_BTREE)
+		return;
+
+	/* skip large extent count inodes */
+	if (ip->i_df.if_nextents > 10000)
+		return;
+
+	bno = NULLFSBLOCK;
+	block = ifp->if_broot;
+	/*
+	 * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
+	 */
+	level = be16_to_cpu(block->bb_level);
+	ASSERT(level > 0);
+	xfs_check_block(block, mp, 1, ifp->if_broot_bytes);
+	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
+	bno = be64_to_cpu(*pp);
+
+	ASSERT(bno != NULLFSBLOCK);
+	ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
+	ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);
+
+	/*
+	 * Go down the tree until leaf level is reached, following the first
+	 * pointer (leftmost) at each level.
+	 */
+	while (level-- > 0) {
+		/* See if buf is in cur first */
+		bp_release = 0;
+		bp = xfs_bmap_get_bp(cur, XFS_FSB_TO_DADDR(mp, bno));
+		if (!bp) {
+			bp_release = 1;
+			error = xfs_btree_read_bufl(mp, NULL, bno, &bp,
+						XFS_BMAP_BTREE_REF,
+						&xfs_bmbt_buf_ops);
+			if (error)
+				goto error_norelse;
+		}
+		block = XFS_BUF_TO_BLOCK(bp);
+		if (level == 0)
+			break;
+
+		/*
+		 * Check this block for basic sanity (increasing keys and
+		 * no duplicate blocks).
+		 */
+
+		xfs_check_block(block, mp, 0, 0);
+		pp = XFS_BMBT_PTR_ADDR(mp, block, 1, mp->m_bmap_dmxr[1]);
+		bno = be64_to_cpu(*pp);
+		if (XFS_IS_CORRUPT(mp, !xfs_verify_fsbno(mp, bno))) {
+			error = -EFSCORRUPTED;
+			goto error0;
+		}
+		if (bp_release) {
+			bp_release = 0;
+			xfs_trans_brelse(NULL, bp);
+		}
+	}
+
+	/*
+	 * Here with bp and block set to the leftmost leaf node in the tree.
+	 */
+	i = 0;
+
+	/*
+	 * Loop over all leaf nodes checking that all extents are in the right order.
+	 */
+	for (;;) {
+		xfs_fsblock_t	nextbno;
+		xfs_extnum_t	num_recs;
+
+
+		num_recs = xfs_btree_get_numrecs(block);
+
+		/*
+		 * Read-ahead the next leaf block, if any.
+		 */
+
+		nextbno = be64_to_cpu(block->bb_u.l.bb_rightsib);
+
+		/*
+		 * Check all the extents to make sure they are OK.
+		 * If we had a previous block, the last entry should
+		 * conform with the first entry in this one.
+		 */
+
+		ep = XFS_BMBT_REC_ADDR(mp, block, 1);
+		if (i) {
+			ASSERT(xfs_bmbt_disk_get_startoff(&last) +
+			       xfs_bmbt_disk_get_blockcount(&last) <=
+			       xfs_bmbt_disk_get_startoff(ep));
+		}
+		for (j = 1; j < num_recs; j++) {
+			nextp = XFS_BMBT_REC_ADDR(mp, block, j + 1);
+			ASSERT(xfs_bmbt_disk_get_startoff(ep) +
+			       xfs_bmbt_disk_get_blockcount(ep) <=
+			       xfs_bmbt_disk_get_startoff(nextp));
+			ep = nextp;
+		}
+
+		last = *ep;
+		i += num_recs;
+		if (bp_release) {
+			bp_release = 0;
+			xfs_trans_brelse(NULL, bp);
+		}
+		bno = nextbno;
+		/*
+		 * If we've reached the end, stop.
+		 */
+		if (bno == NULLFSBLOCK)
+			break;
+
+		bp_release = 0;
+		bp = xfs_bmap_get_bp(cur, XFS_FSB_TO_DADDR(mp, bno));
+		if (!bp) {
+			bp_release = 1;
+			error = xfs_btree_read_bufl(mp, NULL, bno, &bp,
+						XFS_BMAP_BTREE_REF,
+						&xfs_bmbt_buf_ops);
+			if (error)
+				goto error_norelse;
+		}
+		block = XFS_BUF_TO_BLOCK(bp);
+	}
+
+	return;
+
+error0:
+	xfs_warn(mp, "%s: at error0", __func__);
+	if (bp_release)
+		xfs_trans_brelse(NULL, bp);
+error_norelse:
+	xfs_warn(mp, "%s: BAD after btree leaves for %llu extents",
+		__func__, i);
+	xfs_err(mp, "%s: CORRUPTED BTREE OR SOMETHING", __func__);
+	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+	return;
+}
+
+/*
+ * Validate that the bmbt_irecs being returned from bmapi are valid
+ * given the caller's original parameters.  Specifically check the
+ * ranges of the returned irecs to ensure that they only extend beyond
+ * the given parameters if the XFS_BMAPI_ENTIRE flag was set.
+ */
+STATIC void
+xfs_bmap_validate_ret(
+	xfs_fileoff_t		bno,
+	xfs_filblks_t		len,
+	uint32_t		flags,
+	xfs_bmbt_irec_t		*mval,
+	int			nmap,
+	int			ret_nmap)
+{
+	int			i;		/* index to map values */
+
+	ASSERT(ret_nmap <= nmap);
+
+	for (i = 0; i < ret_nmap; i++) {
+		ASSERT(mval[i].br_blockcount > 0);
+		if (!(flags & XFS_BMAPI_ENTIRE)) {
+			ASSERT(mval[i].br_startoff >= bno);
+			ASSERT(mval[i].br_blockcount <= len);
+			ASSERT(mval[i].br_startoff + mval[i].br_blockcount <=
+			       bno + len);
+		} else {
+			ASSERT(mval[i].br_startoff < bno + len);
+			ASSERT(mval[i].br_startoff + mval[i].br_blockcount >
+			       bno);
+		}
+		ASSERT(i == 0 ||
+		       mval[i - 1].br_startoff + mval[i - 1].br_blockcount ==
+		       mval[i].br_startoff);
+		ASSERT(mval[i].br_startblock != DELAYSTARTBLOCK &&
+		       mval[i].br_startblock != HOLESTARTBLOCK);
+		ASSERT(mval[i].br_state == XFS_EXT_NORM ||
+		       mval[i].br_state == XFS_EXT_UNWRITTEN);
+	}
+}
+
+#else
+#define xfs_bmap_check_leaf_extents(cur, ip, whichfork)		do { } while (0)
+#define	xfs_bmap_validate_ret(bno,len,flags,mval,onmap,nmap)	do { } while (0)
+#endif /* DEBUG */
+
+/*
+ * Inode fork format manipulation functions
+ */
+
+/*
+ * Convert the inode format to extent format if it currently is in btree format,
+ * but the extent list is small enough that it fits into the extent format.
+ *
+ * Since the extents are already in-core, all we have to do is give up the space
+ * for the btree root and pitch the leaf block.
+ */
+STATIC int				/* error */
+xfs_bmap_btree_to_extents(
+	struct xfs_trans	*tp,	/* transaction pointer */
+	struct xfs_inode	*ip,	/* incore inode pointer */
+	struct xfs_btree_cur	*cur,	/* btree cursor */
+	int			*logflagsp, /* inode logging flags */
+	int			whichfork)  /* data or attr fork */
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_btree_block	*rblock = ifp->if_broot;
+	struct xfs_btree_block	*cblock;/* child btree block */
+	xfs_fsblock_t		cbno;	/* child block number */
+	struct xfs_buf		*cbp;	/* child block's buffer */
+	int			error;	/* error return value */
+	__be64			*pp;	/* ptr to block address */
+	struct xfs_owner_info	oinfo;
+
+	/* check if we actually need the extent format first: */
+	if (!xfs_bmap_wants_extents(ip, whichfork))
+		return 0;
+
+	ASSERT(cur);
+	ASSERT(whichfork != XFS_COW_FORK);
+	ASSERT(ifp->if_format == XFS_DINODE_FMT_BTREE);
+	ASSERT(be16_to_cpu(rblock->bb_level) == 1);
+	ASSERT(be16_to_cpu(rblock->bb_numrecs) == 1);
+	ASSERT(xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0) == 1);
+
+	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, rblock, 1, ifp->if_broot_bytes);
+	cbno = be64_to_cpu(*pp);
+#ifdef DEBUG
+	if (XFS_IS_CORRUPT(cur->bc_mp, !xfs_btree_check_lptr(cur, cbno, 1)))
+		return -EFSCORRUPTED;
+#endif
+	error = xfs_btree_read_bufl(mp, tp, cbno, &cbp, XFS_BMAP_BTREE_REF,
+				&xfs_bmbt_buf_ops);
+	if (error)
+		return error;
+	cblock = XFS_BUF_TO_BLOCK(cbp);
+	if ((error = xfs_btree_check_block(cur, cblock, 0, cbp)))
+		return error;
+
+	xfs_rmap_ino_bmbt_owner(&oinfo, ip->i_ino, whichfork);
+	error = xfs_free_extent_later(cur->bc_tp, cbno, 1, &oinfo,
+			XFS_AG_RESV_NONE);
+	if (error)
+		return error;
+
+	ip->i_nblocks--;
+	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
+	xfs_trans_binval(tp, cbp);
+	if (cur->bc_levels[0].bp == cbp)
+		cur->bc_levels[0].bp = NULL;
+	xfs_iroot_realloc(ip, -1, whichfork);
+	ASSERT(ifp->if_broot == NULL);
+	ifp->if_format = XFS_DINODE_FMT_EXTENTS;
+	*logflagsp |= XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
+	return 0;
+}
+
+/*
+ * Convert an extents-format file into a btree-format file.
+ * The new file will have a root block (in the inode) and a single child block.
+ */
+STATIC int					/* error */
+xfs_bmap_extents_to_btree(
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* incore inode pointer */
+	struct xfs_btree_cur	**curp,		/* cursor returned to caller */
+	int			wasdel,		/* converting a delayed alloc */
+	int			*logflagsp,	/* inode logging flags */
+	int			whichfork)	/* data or attr fork */
+{
+	struct xfs_btree_block	*ablock;	/* allocated (child) bt block */
+	struct xfs_buf		*abp;		/* buffer for ablock */
+	struct xfs_alloc_arg	args;		/* allocation arguments */
+	struct xfs_bmbt_rec	*arp;		/* child record pointer */
+	struct xfs_btree_block	*block;		/* btree root block */
+	struct xfs_btree_cur	*cur;		/* bmap btree cursor */
+	int			error;		/* error return value */
+	struct xfs_ifork	*ifp;		/* inode fork pointer */
+	struct xfs_bmbt_key	*kp;		/* root block key pointer */
+	struct xfs_mount	*mp;		/* mount structure */
+	xfs_bmbt_ptr_t		*pp;		/* root block address pointer */
+	struct xfs_iext_cursor	icur;
+	struct xfs_bmbt_irec	rec;
+	xfs_extnum_t		cnt = 0;
+
+	mp = ip->i_mount;
+	ASSERT(whichfork != XFS_COW_FORK);
+	ifp = xfs_ifork_ptr(ip, whichfork);
+	ASSERT(ifp->if_format == XFS_DINODE_FMT_EXTENTS);
+
+	/*
+	 * Make space in the inode incore. This needs to be undone if we fail
+	 * to expand the root.
+	 */
+	xfs_iroot_realloc(ip, 1, whichfork);
+
+	/*
+	 * Fill in the root.
+	 */
+	block = ifp->if_broot;
+	xfs_btree_init_block_int(mp, block, XFS_BUF_DADDR_NULL,
+				 XFS_BTNUM_BMAP, 1, 1, ip->i_ino,
+				 XFS_BTREE_LONG_PTRS);
+	/*
+	 * Need a cursor.  Can't allocate until bb_level is filled in.
+	 */
+	cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
+	cur->bc_ino.flags = wasdel ? XFS_BTCUR_BMBT_WASDEL : 0;
+	/*
+	 * Convert to a btree with two levels, one record in root.
+	 */
+	ifp->if_format = XFS_DINODE_FMT_BTREE;
+	memset(&args, 0, sizeof(args));
+	args.tp = tp;
+	args.mp = mp;
+	xfs_rmap_ino_bmbt_owner(&args.oinfo, ip->i_ino, whichfork);
+
+	args.minlen = args.maxlen = args.prod = 1;
+	args.wasdel = wasdel;
+	*logflagsp = 0;
+	error = xfs_alloc_vextent_start_ag(&args,
+				XFS_INO_TO_FSB(mp, ip->i_ino));
+	if (error)
+		goto out_root_realloc;
+
+	/*
+	 * Allocation can't fail, the space was reserved.
+	 */
+	if (WARN_ON_ONCE(args.fsbno == NULLFSBLOCK)) {
+		error = -ENOSPC;
+		goto out_root_realloc;
+	}
+
+	cur->bc_ino.allocated++;
+	ip->i_nblocks++;
+	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, 1L);
+	error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
+			XFS_FSB_TO_DADDR(mp, args.fsbno),
+			mp->m_bsize, 0, &abp);
+	if (error)
+		goto out_unreserve_dquot;
+
+	/*
+	 * Fill in the child block.
+	 */
+	abp->b_ops = &xfs_bmbt_buf_ops;
+	ablock = XFS_BUF_TO_BLOCK(abp);
+	xfs_btree_init_block_int(mp, ablock, xfs_buf_daddr(abp),
+				XFS_BTNUM_BMAP, 0, 0, ip->i_ino,
+				XFS_BTREE_LONG_PTRS);
+
+	for_each_xfs_iext(ifp, &icur, &rec) {
+		if (isnullstartblock(rec.br_startblock))
+			continue;
+		arp = XFS_BMBT_REC_ADDR(mp, ablock, 1 + cnt);
+		xfs_bmbt_disk_set_all(arp, &rec);
+		cnt++;
+	}
+	ASSERT(cnt == ifp->if_nextents);
+	xfs_btree_set_numrecs(ablock, cnt);
+
+	/*
+	 * Fill in the root key and pointer.
+	 */
+	kp = XFS_BMBT_KEY_ADDR(mp, block, 1);
+	arp = XFS_BMBT_REC_ADDR(mp, ablock, 1);
+	kp->br_startoff = cpu_to_be64(xfs_bmbt_disk_get_startoff(arp));
+	pp = XFS_BMBT_PTR_ADDR(mp, block, 1, xfs_bmbt_get_maxrecs(cur,
+						be16_to_cpu(block->bb_level)));
+	*pp = cpu_to_be64(args.fsbno);
+
+	/*
+	 * Do all this logging at the end so that
+	 * the root is at the right level.
+	 */
+	xfs_btree_log_block(cur, abp, XFS_BB_ALL_BITS);
+	xfs_btree_log_recs(cur, abp, 1, be16_to_cpu(ablock->bb_numrecs));
+	ASSERT(*curp == NULL);
+	*curp = cur;
+	*logflagsp = XFS_ILOG_CORE | xfs_ilog_fbroot(whichfork);
+	return 0;
+
+out_unreserve_dquot:
+	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
+out_root_realloc:
+	xfs_iroot_realloc(ip, -1, whichfork);
+	ifp->if_format = XFS_DINODE_FMT_EXTENTS;
+	ASSERT(ifp->if_broot == NULL);
+	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+
+	return error;
+}
+
+/*
+ * Convert a local file to an extents file.
+ * This code is out of bounds for data forks of regular files,
+ * since the file data needs to get logged so things will stay consistent.
+ * (The bmap-level manipulations are ok, though).
+ */
+void
+xfs_bmap_local_to_extents_empty(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	int			whichfork)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+
+	ASSERT(whichfork != XFS_COW_FORK);
+	ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
+	ASSERT(ifp->if_bytes == 0);
+	ASSERT(ifp->if_nextents == 0);
+
+	xfs_bmap_forkoff_reset(ip, whichfork);
+	ifp->if_u1.if_root = NULL;
+	ifp->if_height = 0;
+	ifp->if_format = XFS_DINODE_FMT_EXTENTS;
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+}
+
+
+STATIC int				/* error */
+xfs_bmap_local_to_extents(
+	xfs_trans_t	*tp,		/* transaction pointer */
+	xfs_inode_t	*ip,		/* incore inode pointer */
+	xfs_extlen_t	total,		/* total blocks needed by transaction */
+	int		*logflagsp,	/* inode logging flags */
+	int		whichfork,
+	void		(*init_fn)(struct xfs_trans *tp,
+				   struct xfs_buf *bp,
+				   struct xfs_inode *ip,
+				   struct xfs_ifork *ifp))
+{
+	int		error = 0;
+	int		flags;		/* logging flags returned */
+	struct xfs_ifork *ifp;		/* inode fork pointer */
+	xfs_alloc_arg_t	args;		/* allocation arguments */
+	struct xfs_buf	*bp;		/* buffer for extent block */
+	struct xfs_bmbt_irec rec;
+	struct xfs_iext_cursor icur;
+
+	/*
+	 * We don't want to deal with the case of keeping inode data inline yet.
+	 * So sending the data fork of a regular inode is invalid.
+	 */
+	ASSERT(!(S_ISREG(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK));
+	ifp = xfs_ifork_ptr(ip, whichfork);
+	ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
+
+	if (!ifp->if_bytes) {
+		xfs_bmap_local_to_extents_empty(tp, ip, whichfork);
+		flags = XFS_ILOG_CORE;
+		goto done;
+	}
+
+	flags = 0;
+	error = 0;
+	memset(&args, 0, sizeof(args));
+	args.tp = tp;
+	args.mp = ip->i_mount;
+	args.total = total;
+	args.minlen = args.maxlen = args.prod = 1;
+	xfs_rmap_ino_owner(&args.oinfo, ip->i_ino, whichfork, 0);
+
+	/*
+	 * Allocate a block.  We know we need only one, since the
+	 * file currently fits in an inode.
+	 */
+	args.total = total;
+	args.minlen = args.maxlen = args.prod = 1;
+	error = xfs_alloc_vextent_start_ag(&args,
+			XFS_INO_TO_FSB(args.mp, ip->i_ino));
+	if (error)
+		goto done;
+
+	/* Can't fail, the space was reserved. */
+	ASSERT(args.fsbno != NULLFSBLOCK);
+	ASSERT(args.len == 1);
+	error = xfs_trans_get_buf(tp, args.mp->m_ddev_targp,
+			XFS_FSB_TO_DADDR(args.mp, args.fsbno),
+			args.mp->m_bsize, 0, &bp);
+	if (error)
+		goto done;
+
+	/*
+	 * Initialize the block, copy the data and log the remote buffer.
+	 *
+	 * The callout is responsible for logging because the remote format
+	 * might differ from the local format and thus we don't know how much to
+	 * log here. Note that init_fn must also set the buffer log item type
+	 * correctly.
+	 */
+	init_fn(tp, bp, ip, ifp);
+
+	/* account for the change in fork size */
+	xfs_idata_realloc(ip, -ifp->if_bytes, whichfork);
+	xfs_bmap_local_to_extents_empty(tp, ip, whichfork);
+	flags |= XFS_ILOG_CORE;
+
+	ifp->if_u1.if_root = NULL;
+	ifp->if_height = 0;
+
+	rec.br_startoff = 0;
+	rec.br_startblock = args.fsbno;
+	rec.br_blockcount = 1;
+	rec.br_state = XFS_EXT_NORM;
+	xfs_iext_first(ifp, &icur);
+	xfs_iext_insert(ip, &icur, &rec, 0);
+
+	ifp->if_nextents = 1;
+	ip->i_nblocks = 1;
+	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, 1L);
+	flags |= xfs_ilog_fext(whichfork);
+
+done:
+	*logflagsp = flags;
+	return error;
+}
+
+/*
+ * Called from xfs_bmap_add_attrfork to handle btree format files.
+ */
+STATIC int					/* error */
+xfs_bmap_add_attrfork_btree(
+	xfs_trans_t		*tp,		/* transaction pointer */
+	xfs_inode_t		*ip,		/* incore inode pointer */
+	int			*flags)		/* inode logging flags */
+{
+	struct xfs_btree_block	*block = ip->i_df.if_broot;
+	struct xfs_btree_cur	*cur;		/* btree cursor */
+	int			error;		/* error return value */
+	xfs_mount_t		*mp;		/* file system mount struct */
+	int			stat;		/* newroot status */
+
+	mp = ip->i_mount;
+
+	if (XFS_BMAP_BMDR_SPACE(block) <= xfs_inode_data_fork_size(ip))
+		*flags |= XFS_ILOG_DBROOT;
+	else {
+		cur = xfs_bmbt_init_cursor(mp, tp, ip, XFS_DATA_FORK);
+		error = xfs_bmbt_lookup_first(cur, &stat);
+		if (error)
+			goto error0;
+		/* must be at least one entry */
+		if (XFS_IS_CORRUPT(mp, stat != 1)) {
+			error = -EFSCORRUPTED;
+			goto error0;
+		}
+		if ((error = xfs_btree_new_iroot(cur, flags, &stat)))
+			goto error0;
+		if (stat == 0) {
+			xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+			return -ENOSPC;
+		}
+		cur->bc_ino.allocated = 0;
+		xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+	}
+	return 0;
+error0:
+	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+	return error;
+}
+
+/*
+ * Called from xfs_bmap_add_attrfork to handle extents format files.
+ */
+STATIC int					/* error */
+xfs_bmap_add_attrfork_extents(
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* incore inode pointer */
+	int			*flags)		/* inode logging flags */
+{
+	struct xfs_btree_cur	*cur;		/* bmap btree cursor */
+	int			error;		/* error return value */
+
+	if (ip->i_df.if_nextents * sizeof(struct xfs_bmbt_rec) <=
+	    xfs_inode_data_fork_size(ip))
+		return 0;
+	cur = NULL;
+	error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0, flags,
+					  XFS_DATA_FORK);
+	if (cur) {
+		cur->bc_ino.allocated = 0;
+		xfs_btree_del_cursor(cur, error);
+	}
+	return error;
+}
+
+/*
+ * Called from xfs_bmap_add_attrfork to handle local format files. Each
+ * different data fork content type needs a different callout to do the
+ * conversion. Some are basic and only require special block initialisation
+ * callouts for the data formating, others (directories) are so specialised they
+ * handle everything themselves.
+ *
+ * XXX (dgc): investigate whether directory conversion can use the generic
+ * formatting callout. It should be possible - it's just a very complex
+ * formatter.
+ */
+STATIC int					/* error */
+xfs_bmap_add_attrfork_local(
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* incore inode pointer */
+	int			*flags)		/* inode logging flags */
+{
+	struct xfs_da_args	dargs;		/* args for dir/attr code */
+
+	if (ip->i_df.if_bytes <= xfs_inode_data_fork_size(ip))
+		return 0;
+
+	if (S_ISDIR(VFS_I(ip)->i_mode)) {
+		memset(&dargs, 0, sizeof(dargs));
+		dargs.geo = ip->i_mount->m_dir_geo;
+		dargs.dp = ip;
+		dargs.total = dargs.geo->fsbcount;
+		dargs.whichfork = XFS_DATA_FORK;
+		dargs.trans = tp;
+		return xfs_dir2_sf_to_block(&dargs);
+	}
+
+	if (S_ISLNK(VFS_I(ip)->i_mode))
+		return xfs_bmap_local_to_extents(tp, ip, 1, flags,
+						 XFS_DATA_FORK,
+						 xfs_symlink_local_to_remote);
+
+	/* should only be called for types that support local format data */
+	ASSERT(0);
+	return -EFSCORRUPTED;
+}
+
+/*
+ * Set an inode attr fork offset based on the format of the data fork.
+ */
+static int
+xfs_bmap_set_attrforkoff(
+	struct xfs_inode	*ip,
+	int			size,
+	int			*version)
+{
+	int			default_size = xfs_default_attroffset(ip) >> 3;
+
+	switch (ip->i_df.if_format) {
+	case XFS_DINODE_FMT_DEV:
+		ip->i_forkoff = default_size;
+		break;
+	case XFS_DINODE_FMT_LOCAL:
+	case XFS_DINODE_FMT_EXTENTS:
+	case XFS_DINODE_FMT_BTREE:
+		ip->i_forkoff = xfs_attr_shortform_bytesfit(ip, size);
+		if (!ip->i_forkoff)
+			ip->i_forkoff = default_size;
+		else if (xfs_has_attr2(ip->i_mount) && version)
+			*version = 2;
+		break;
+	default:
+		ASSERT(0);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Convert inode from non-attributed to attributed.
+ * Must not be in a transaction, ip must not be locked.
+ */
+int						/* error code */
+xfs_bmap_add_attrfork(
+	xfs_inode_t		*ip,		/* incore inode pointer */
+	int			size,		/* space new attribute needs */
+	int			rsvd)		/* xact may use reserved blks */
+{
+	xfs_mount_t		*mp;		/* mount structure */
+	xfs_trans_t		*tp;		/* transaction pointer */
+	int			blks;		/* space reservation */
+	int			version = 1;	/* superblock attr version */
+	int			logflags;	/* logging flags */
+	int			error;		/* error return value */
+
+	ASSERT(xfs_inode_has_attr_fork(ip) == 0);
+
+	mp = ip->i_mount;
+	ASSERT(!XFS_NOT_DQATTACHED(mp, ip));
+
+	blks = XFS_ADDAFORK_SPACE_RES(mp);
+
+	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_addafork, blks, 0,
+			rsvd, &tp);
+	if (error)
+		return error;
+	if (xfs_inode_has_attr_fork(ip))
+		goto trans_cancel;
+
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+	error = xfs_bmap_set_attrforkoff(ip, size, &version);
+	if (error)
+		goto trans_cancel;
+
+	xfs_ifork_init_attr(ip, XFS_DINODE_FMT_EXTENTS, 0);
+	logflags = 0;
+	switch (ip->i_df.if_format) {
+	case XFS_DINODE_FMT_LOCAL:
+		error = xfs_bmap_add_attrfork_local(tp, ip, &logflags);
+		break;
+	case XFS_DINODE_FMT_EXTENTS:
+		error = xfs_bmap_add_attrfork_extents(tp, ip, &logflags);
+		break;
+	case XFS_DINODE_FMT_BTREE:
+		error = xfs_bmap_add_attrfork_btree(tp, ip, &logflags);
+		break;
+	default:
+		error = 0;
+		break;
+	}
+	if (logflags)
+		xfs_trans_log_inode(tp, ip, logflags);
+	if (error)
+		goto trans_cancel;
+	if (!xfs_has_attr(mp) ||
+	   (!xfs_has_attr2(mp) && version == 2)) {
+		bool log_sb = false;
+
+		spin_lock(&mp->m_sb_lock);
+		if (!xfs_has_attr(mp)) {
+			xfs_add_attr(mp);
+			log_sb = true;
+		}
+		if (!xfs_has_attr2(mp) && version == 2) {
+			xfs_add_attr2(mp);
+			log_sb = true;
+		}
+		spin_unlock(&mp->m_sb_lock);
+		if (log_sb)
+			xfs_log_sb(tp);
+	}
+
+	error = xfs_trans_commit(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+
+trans_cancel:
+	xfs_trans_cancel(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+}
+
+/*
+ * Internal and external extent tree search functions.
+ */
+
+struct xfs_iread_state {
+	struct xfs_iext_cursor	icur;
+	xfs_extnum_t		loaded;
+};
+
+int
+xfs_bmap_complain_bad_rec(
+	struct xfs_inode		*ip,
+	int				whichfork,
+	xfs_failaddr_t			fa,
+	const struct xfs_bmbt_irec	*irec)
+{
+	struct xfs_mount		*mp = ip->i_mount;
+	const char			*forkname;
+
+	switch (whichfork) {
+	case XFS_DATA_FORK:	forkname = "data"; break;
+	case XFS_ATTR_FORK:	forkname = "attr"; break;
+	case XFS_COW_FORK:	forkname = "CoW"; break;
+	default:		forkname = "???"; break;
+	}
+
+	xfs_warn(mp,
+ "Bmap BTree record corruption in inode 0x%llx %s fork detected at %pS!",
+				ip->i_ino, forkname, fa);
+	xfs_warn(mp,
+		"Offset 0x%llx, start block 0x%llx, block count 0x%llx state 0x%x",
+		irec->br_startoff, irec->br_startblock, irec->br_blockcount,
+		irec->br_state);
+
+	return -EFSCORRUPTED;
+}
+
+/* Stuff every bmbt record from this block into the incore extent map. */
+static int
+xfs_iread_bmbt_block(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	void			*priv)
+{
+	struct xfs_iread_state	*ir = priv;
+	struct xfs_mount	*mp = cur->bc_mp;
+	struct xfs_inode	*ip = cur->bc_ino.ip;
+	struct xfs_btree_block	*block;
+	struct xfs_buf		*bp;
+	struct xfs_bmbt_rec	*frp;
+	xfs_extnum_t		num_recs;
+	xfs_extnum_t		j;
+	int			whichfork = cur->bc_ino.whichfork;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+
+	block = xfs_btree_get_block(cur, level, &bp);
+
+	/* Abort if we find more records than nextents. */
+	num_recs = xfs_btree_get_numrecs(block);
+	if (unlikely(ir->loaded + num_recs > ifp->if_nextents)) {
+		xfs_warn(ip->i_mount, "corrupt dinode %llu, (btree extents).",
+				(unsigned long long)ip->i_ino);
+		xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__, block,
+				sizeof(*block), __this_address);
+		return -EFSCORRUPTED;
+	}
+
+	/* Copy records into the incore cache. */
+	frp = XFS_BMBT_REC_ADDR(mp, block, 1);
+	for (j = 0; j < num_recs; j++, frp++, ir->loaded++) {
+		struct xfs_bmbt_irec	new;
+		xfs_failaddr_t		fa;
+
+		xfs_bmbt_disk_get_all(frp, &new);
+		fa = xfs_bmap_validate_extent(ip, whichfork, &new);
+		if (fa) {
+			xfs_inode_verifier_error(ip, -EFSCORRUPTED,
+					"xfs_iread_extents(2)", frp,
+					sizeof(*frp), fa);
+			return xfs_bmap_complain_bad_rec(ip, whichfork, fa,
+					&new);
+		}
+		xfs_iext_insert(ip, &ir->icur, &new,
+				xfs_bmap_fork_to_state(whichfork));
+		trace_xfs_read_extent(ip, &ir->icur,
+				xfs_bmap_fork_to_state(whichfork), _THIS_IP_);
+		xfs_iext_next(ifp, &ir->icur);
+	}
+
+	return 0;
+}
+
+/*
+ * Read in extents from a btree-format inode.
+ */
+int
+xfs_iread_extents(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	int			whichfork)
+{
+	struct xfs_iread_state	ir;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_btree_cur	*cur;
+	int			error;
+
+	if (!xfs_need_iread_extents(ifp))
+		return 0;
+
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+
+	ir.loaded = 0;
+	xfs_iext_first(ifp, &ir.icur);
+	cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
+	error = xfs_btree_visit_blocks(cur, xfs_iread_bmbt_block,
+			XFS_BTREE_VISIT_RECORDS, &ir);
+	xfs_btree_del_cursor(cur, error);
+	if (error)
+		goto out;
+
+	if (XFS_IS_CORRUPT(mp, ir.loaded != ifp->if_nextents)) {
+		error = -EFSCORRUPTED;
+		goto out;
+	}
+	ASSERT(ir.loaded == xfs_iext_count(ifp));
+	/*
+	 * Use release semantics so that we can use acquire semantics in
+	 * xfs_need_iread_extents and be guaranteed to see a valid mapping tree
+	 * after that load.
+	 */
+	smp_store_release(&ifp->if_needextents, 0);
+	return 0;
+out:
+	xfs_iext_destroy(ifp);
+	return error;
+}
+
+/*
+ * Returns the relative block number of the first unused block(s) in the given
+ * fork with at least "len" logically contiguous blocks free.  This is the
+ * lowest-address hole if the fork has holes, else the first block past the end
+ * of fork.  Return 0 if the fork is currently local (in-inode).
+ */
+int						/* error */
+xfs_bmap_first_unused(
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* incore inode */
+	xfs_extlen_t		len,		/* size of hole to find */
+	xfs_fileoff_t		*first_unused,	/* unused block */
+	int			whichfork)	/* data or attr fork */
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_bmbt_irec	got;
+	struct xfs_iext_cursor	icur;
+	xfs_fileoff_t		lastaddr = 0;
+	xfs_fileoff_t		lowest, max;
+	int			error;
+
+	if (ifp->if_format == XFS_DINODE_FMT_LOCAL) {
+		*first_unused = 0;
+		return 0;
+	}
+
+	ASSERT(xfs_ifork_has_extents(ifp));
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	lowest = max = *first_unused;
+	for_each_xfs_iext(ifp, &icur, &got) {
+		/*
+		 * See if the hole before this extent will work.
+		 */
+		if (got.br_startoff >= lowest + len &&
+		    got.br_startoff - max >= len)
+			break;
+		lastaddr = got.br_startoff + got.br_blockcount;
+		max = XFS_FILEOFF_MAX(lastaddr, lowest);
+	}
+
+	*first_unused = max;
+	return 0;
+}
+
+/*
+ * Returns the file-relative block number of the last block - 1 before
+ * last_block (input value) in the file.
+ * This is not based on i_size, it is based on the extent records.
+ * Returns 0 for local files, as they do not have extent records.
+ */
+int						/* error */
+xfs_bmap_last_before(
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* incore inode */
+	xfs_fileoff_t		*last_block,	/* last block */
+	int			whichfork)	/* data or attr fork */
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_bmbt_irec	got;
+	struct xfs_iext_cursor	icur;
+	int			error;
+
+	switch (ifp->if_format) {
+	case XFS_DINODE_FMT_LOCAL:
+		*last_block = 0;
+		return 0;
+	case XFS_DINODE_FMT_BTREE:
+	case XFS_DINODE_FMT_EXTENTS:
+		break;
+	default:
+		ASSERT(0);
+		return -EFSCORRUPTED;
+	}
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &icur, &got))
+		*last_block = 0;
+	return 0;
+}
+
+int
+xfs_bmap_last_extent(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_bmbt_irec	*rec,
+	int			*is_empty)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_iext_cursor	icur;
+	int			error;
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	xfs_iext_last(ifp, &icur);
+	if (!xfs_iext_get_extent(ifp, &icur, rec))
+		*is_empty = 1;
+	else
+		*is_empty = 0;
+	return 0;
+}
+
+/*
+ * Check the last inode extent to determine whether this allocation will result
+ * in blocks being allocated at the end of the file. When we allocate new data
+ * blocks at the end of the file which do not start at the previous data block,
+ * we will try to align the new blocks at stripe unit boundaries.
+ *
+ * Returns 1 in bma->aeof if the file (fork) is empty as any new write will be
+ * at, or past the EOF.
+ */
+STATIC int
+xfs_bmap_isaeof(
+	struct xfs_bmalloca	*bma,
+	int			whichfork)
+{
+	struct xfs_bmbt_irec	rec;
+	int			is_empty;
+	int			error;
+
+	bma->aeof = false;
+	error = xfs_bmap_last_extent(NULL, bma->ip, whichfork, &rec,
+				     &is_empty);
+	if (error)
+		return error;
+
+	if (is_empty) {
+		bma->aeof = true;
+		return 0;
+	}
+
+	/*
+	 * Check if we are allocation or past the last extent, or at least into
+	 * the last delayed allocated extent.
+	 */
+	bma->aeof = bma->offset >= rec.br_startoff + rec.br_blockcount ||
+		(bma->offset >= rec.br_startoff &&
+		 isnullstartblock(rec.br_startblock));
+	return 0;
+}
+
+/*
+ * Returns the file-relative block number of the first block past eof in
+ * the file.  This is not based on i_size, it is based on the extent records.
+ * Returns 0 for local files, as they do not have extent records.
+ */
+int
+xfs_bmap_last_offset(
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		*last_block,
+	int			whichfork)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_bmbt_irec	rec;
+	int			is_empty;
+	int			error;
+
+	*last_block = 0;
+
+	if (ifp->if_format == XFS_DINODE_FMT_LOCAL)
+		return 0;
+
+	if (XFS_IS_CORRUPT(ip->i_mount, !xfs_ifork_has_extents(ifp)))
+		return -EFSCORRUPTED;
+
+	error = xfs_bmap_last_extent(NULL, ip, whichfork, &rec, &is_empty);
+	if (error || is_empty)
+		return error;
+
+	*last_block = rec.br_startoff + rec.br_blockcount;
+	return 0;
+}
+
+/*
+ * Extent tree manipulation functions used during allocation.
+ */
+
+/*
+ * Convert a delayed allocation to a real allocation.
+ */
+STATIC int				/* error */
+xfs_bmap_add_extent_delay_real(
+	struct xfs_bmalloca	*bma,
+	int			whichfork)
+{
+	struct xfs_mount	*mp = bma->ip->i_mount;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
+	struct xfs_bmbt_irec	*new = &bma->got;
+	int			error;	/* error return value */
+	int			i;	/* temp state */
+	xfs_fileoff_t		new_endoff;	/* end offset of new entry */
+	xfs_bmbt_irec_t		r[3];	/* neighbor extent entries */
+					/* left is 0, right is 1, prev is 2 */
+	int			rval=0;	/* return value (logging flags) */
+	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
+	xfs_filblks_t		da_new; /* new count del alloc blocks used */
+	xfs_filblks_t		da_old; /* old count del alloc blocks used */
+	xfs_filblks_t		temp=0;	/* value for da_new calculations */
+	int			tmp_rval;	/* partial logging flags */
+	struct xfs_bmbt_irec	old;
+
+	ASSERT(whichfork != XFS_ATTR_FORK);
+	ASSERT(!isnullstartblock(new->br_startblock));
+	ASSERT(!bma->cur ||
+	       (bma->cur->bc_ino.flags & XFS_BTCUR_BMBT_WASDEL));
+
+	XFS_STATS_INC(mp, xs_add_exlist);
+
+#define	LEFT		r[0]
+#define	RIGHT		r[1]
+#define	PREV		r[2]
+
+	/*
+	 * Set up a bunch of variables to make the tests simpler.
+	 */
+	xfs_iext_get_extent(ifp, &bma->icur, &PREV);
+	new_endoff = new->br_startoff + new->br_blockcount;
+	ASSERT(isnullstartblock(PREV.br_startblock));
+	ASSERT(PREV.br_startoff <= new->br_startoff);
+	ASSERT(PREV.br_startoff + PREV.br_blockcount >= new_endoff);
+
+	da_old = startblockval(PREV.br_startblock);
+	da_new = 0;
+
+	/*
+	 * Set flags determining what part of the previous delayed allocation
+	 * extent is being replaced by a real allocation.
+	 */
+	if (PREV.br_startoff == new->br_startoff)
+		state |= BMAP_LEFT_FILLING;
+	if (PREV.br_startoff + PREV.br_blockcount == new_endoff)
+		state |= BMAP_RIGHT_FILLING;
+
+	/*
+	 * Check and set flags if this segment has a left neighbor.
+	 * Don't set contiguous if the combined extent would be too large.
+	 */
+	if (xfs_iext_peek_prev_extent(ifp, &bma->icur, &LEFT)) {
+		state |= BMAP_LEFT_VALID;
+		if (isnullstartblock(LEFT.br_startblock))
+			state |= BMAP_LEFT_DELAY;
+	}
+
+	if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
+	    LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
+	    LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
+	    LEFT.br_state == new->br_state &&
+	    LEFT.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
+		state |= BMAP_LEFT_CONTIG;
+
+	/*
+	 * Check and set flags if this segment has a right neighbor.
+	 * Don't set contiguous if the combined extent would be too large.
+	 * Also check for all-three-contiguous being too large.
+	 */
+	if (xfs_iext_peek_next_extent(ifp, &bma->icur, &RIGHT)) {
+		state |= BMAP_RIGHT_VALID;
+		if (isnullstartblock(RIGHT.br_startblock))
+			state |= BMAP_RIGHT_DELAY;
+	}
+
+	if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
+	    new_endoff == RIGHT.br_startoff &&
+	    new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
+	    new->br_state == RIGHT.br_state &&
+	    new->br_blockcount + RIGHT.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
+	    ((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
+		       BMAP_RIGHT_FILLING)) !=
+		      (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
+		       BMAP_RIGHT_FILLING) ||
+	     LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
+			<= XFS_MAX_BMBT_EXTLEN))
+		state |= BMAP_RIGHT_CONTIG;
+
+	error = 0;
+	/*
+	 * Switch out based on the FILLING and CONTIG state bits.
+	 */
+	switch (state & (BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
+			 BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG)) {
+	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
+	     BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
+		/*
+		 * Filling in all of a previously delayed allocation extent.
+		 * The left and right neighbors are both contiguous with new.
+		 */
+		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
+
+		xfs_iext_remove(bma->ip, &bma->icur, state);
+		xfs_iext_remove(bma->ip, &bma->icur, state);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
+		ifp->if_nextents--;
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(bma->cur, &RIGHT, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_delete(bma->cur, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_decrement(bma->cur, 0, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(bma->cur, &LEFT);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
+		/*
+		 * Filling in all of a previously delayed allocation extent.
+		 * The left neighbor is contiguous, the right is not.
+		 */
+		old = LEFT;
+		LEFT.br_blockcount += PREV.br_blockcount;
+
+		xfs_iext_remove(bma->ip, &bma->icur, state);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_DEXT;
+		else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(bma->cur, &LEFT);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
+		/*
+		 * Filling in all of a previously delayed allocation extent.
+		 * The right neighbor is contiguous, the left is not. Take care
+		 * with delay -> unwritten extent allocation here because the
+		 * delalloc record we are overwriting is always written.
+		 */
+		PREV.br_startblock = new->br_startblock;
+		PREV.br_blockcount += RIGHT.br_blockcount;
+		PREV.br_state = new->br_state;
+
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_remove(bma->ip, &bma->icur, state);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_DEXT;
+		else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(bma->cur, &RIGHT, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(bma->cur, &PREV);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
+		/*
+		 * Filling in all of a previously delayed allocation extent.
+		 * Neither the left nor right neighbors are contiguous with
+		 * the new one.
+		 */
+		PREV.br_startblock = new->br_startblock;
+		PREV.br_state = new->br_state;
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
+		ifp->if_nextents++;
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 0)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_insert(bma->cur, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG:
+		/*
+		 * Filling in the first part of a previous delayed allocation.
+		 * The left neighbor is contiguous.
+		 */
+		old = LEFT;
+		temp = PREV.br_blockcount - new->br_blockcount;
+		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
+				startblockval(PREV.br_startblock));
+
+		LEFT.br_blockcount += new->br_blockcount;
+
+		PREV.br_blockcount = temp;
+		PREV.br_startoff += new->br_blockcount;
+		PREV.br_startblock = nullstartblock(da_new);
+
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
+		xfs_iext_prev(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_DEXT;
+		else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(bma->cur, &LEFT);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING:
+		/*
+		 * Filling in the first part of a previous delayed allocation.
+		 * The left neighbor is not contiguous.
+		 */
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
+		ifp->if_nextents++;
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 0)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_insert(bma->cur, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+
+		if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
+			error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
+					&bma->cur, 1, &tmp_rval, whichfork);
+			rval |= tmp_rval;
+			if (error)
+				goto done;
+		}
+
+		temp = PREV.br_blockcount - new->br_blockcount;
+		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
+			startblockval(PREV.br_startblock) -
+			(bma->cur ? bma->cur->bc_ino.allocated : 0));
+
+		PREV.br_startoff = new_endoff;
+		PREV.br_blockcount = temp;
+		PREV.br_startblock = nullstartblock(da_new);
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
+		xfs_iext_prev(ifp, &bma->icur);
+		break;
+
+	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
+		/*
+		 * Filling in the last part of a previous delayed allocation.
+		 * The right neighbor is contiguous with the new allocation.
+		 */
+		old = RIGHT;
+		RIGHT.br_startoff = new->br_startoff;
+		RIGHT.br_startblock = new->br_startblock;
+		RIGHT.br_blockcount += new->br_blockcount;
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_DEXT;
+		else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(bma->cur, &RIGHT);
+			if (error)
+				goto done;
+		}
+
+		temp = PREV.br_blockcount - new->br_blockcount;
+		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
+			startblockval(PREV.br_startblock));
+
+		PREV.br_blockcount = temp;
+		PREV.br_startblock = nullstartblock(da_new);
+
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &RIGHT);
+		break;
+
+	case BMAP_RIGHT_FILLING:
+		/*
+		 * Filling in the last part of a previous delayed allocation.
+		 * The right neighbor is not contiguous.
+		 */
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
+		ifp->if_nextents++;
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 0)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_insert(bma->cur, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+
+		if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
+			error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
+				&bma->cur, 1, &tmp_rval, whichfork);
+			rval |= tmp_rval;
+			if (error)
+				goto done;
+		}
+
+		temp = PREV.br_blockcount - new->br_blockcount;
+		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
+			startblockval(PREV.br_startblock) -
+			(bma->cur ? bma->cur->bc_ino.allocated : 0));
+
+		PREV.br_startblock = nullstartblock(da_new);
+		PREV.br_blockcount = temp;
+		xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
+		xfs_iext_next(ifp, &bma->icur);
+		break;
+
+	case 0:
+		/*
+		 * Filling in the middle part of a previous delayed allocation.
+		 * Contiguity is impossible here.
+		 * This case is avoided almost all the time.
+		 *
+		 * We start with a delayed allocation:
+		 *
+		 * +ddddddddddddddddddddddddddddddddddddddddddddddddddddddd+
+		 *  PREV @ idx
+		 *
+	         * and we are allocating:
+		 *                     +rrrrrrrrrrrrrrrrr+
+		 *			      new
+		 *
+		 * and we set it up for insertion as:
+		 * +ddddddddddddddddddd+rrrrrrrrrrrrrrrrr+ddddddddddddddddd+
+		 *                            new
+		 *  PREV @ idx          LEFT              RIGHT
+		 *                      inserted at idx + 1
+		 */
+		old = PREV;
+
+		/* LEFT is the new middle */
+		LEFT = *new;
+
+		/* RIGHT is the new right */
+		RIGHT.br_state = PREV.br_state;
+		RIGHT.br_startoff = new_endoff;
+		RIGHT.br_blockcount =
+			PREV.br_startoff + PREV.br_blockcount - new_endoff;
+		RIGHT.br_startblock =
+			nullstartblock(xfs_bmap_worst_indlen(bma->ip,
+					RIGHT.br_blockcount));
+
+		/* truncate PREV */
+		PREV.br_blockcount = new->br_startoff - PREV.br_startoff;
+		PREV.br_startblock =
+			nullstartblock(xfs_bmap_worst_indlen(bma->ip,
+					PREV.br_blockcount));
+		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
+
+		xfs_iext_next(ifp, &bma->icur);
+		xfs_iext_insert(bma->ip, &bma->icur, &RIGHT, state);
+		xfs_iext_insert(bma->ip, &bma->icur, &LEFT, state);
+		ifp->if_nextents++;
+
+		if (bma->cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 0)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_insert(bma->cur, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+
+		if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
+			error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
+					&bma->cur, 1, &tmp_rval, whichfork);
+			rval |= tmp_rval;
+			if (error)
+				goto done;
+		}
+
+		da_new = startblockval(PREV.br_startblock) +
+			 startblockval(RIGHT.br_startblock);
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_CONTIG:
+	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
+	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+	case BMAP_LEFT_CONTIG:
+	case BMAP_RIGHT_CONTIG:
+		/*
+		 * These cases are all impossible.
+		 */
+		ASSERT(0);
+	}
+
+	/* add reverse mapping unless caller opted out */
+	if (!(bma->flags & XFS_BMAPI_NORMAP))
+		xfs_rmap_map_extent(bma->tp, bma->ip, whichfork, new);
+
+	/* convert to a btree if necessary */
+	if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
+		int	tmp_logflags;	/* partial log flag return val */
+
+		ASSERT(bma->cur == NULL);
+		error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
+				&bma->cur, da_old > 0, &tmp_logflags,
+				whichfork);
+		bma->logflags |= tmp_logflags;
+		if (error)
+			goto done;
+	}
+
+	if (da_new != da_old)
+		xfs_mod_delalloc(mp, (int64_t)da_new - da_old);
+
+	if (bma->cur) {
+		da_new += bma->cur->bc_ino.allocated;
+		bma->cur->bc_ino.allocated = 0;
+	}
+
+	/* adjust for changes in reserved delayed indirect blocks */
+	if (da_new != da_old) {
+		ASSERT(state == 0 || da_new < da_old);
+		error = xfs_mod_fdblocks(mp, (int64_t)(da_old - da_new),
+				false);
+	}
+
+	xfs_bmap_check_leaf_extents(bma->cur, bma->ip, whichfork);
+done:
+	if (whichfork != XFS_COW_FORK)
+		bma->logflags |= rval;
+	return error;
+#undef	LEFT
+#undef	RIGHT
+#undef	PREV
+}
+
+/*
+ * Convert an unwritten allocation to a real allocation or vice versa.
+ */
+int					/* error */
+xfs_bmap_add_extent_unwritten_real(
+	struct xfs_trans	*tp,
+	xfs_inode_t		*ip,	/* incore inode pointer */
+	int			whichfork,
+	struct xfs_iext_cursor	*icur,
+	struct xfs_btree_cur	**curp,	/* if *curp is null, not a btree */
+	xfs_bmbt_irec_t		*new,	/* new data to add to file extents */
+	int			*logflagsp) /* inode logging flags */
+{
+	struct xfs_btree_cur	*cur;	/* btree cursor */
+	int			error;	/* error return value */
+	int			i;	/* temp state */
+	struct xfs_ifork	*ifp;	/* inode fork pointer */
+	xfs_fileoff_t		new_endoff;	/* end offset of new entry */
+	xfs_bmbt_irec_t		r[3];	/* neighbor extent entries */
+					/* left is 0, right is 1, prev is 2 */
+	int			rval=0;	/* return value (logging flags) */
+	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_bmbt_irec	old;
+
+	*logflagsp = 0;
+
+	cur = *curp;
+	ifp = xfs_ifork_ptr(ip, whichfork);
+
+	ASSERT(!isnullstartblock(new->br_startblock));
+
+	XFS_STATS_INC(mp, xs_add_exlist);
+
+#define	LEFT		r[0]
+#define	RIGHT		r[1]
+#define	PREV		r[2]
+
+	/*
+	 * Set up a bunch of variables to make the tests simpler.
+	 */
+	error = 0;
+	xfs_iext_get_extent(ifp, icur, &PREV);
+	ASSERT(new->br_state != PREV.br_state);
+	new_endoff = new->br_startoff + new->br_blockcount;
+	ASSERT(PREV.br_startoff <= new->br_startoff);
+	ASSERT(PREV.br_startoff + PREV.br_blockcount >= new_endoff);
+
+	/*
+	 * Set flags determining what part of the previous oldext allocation
+	 * extent is being replaced by a newext allocation.
+	 */
+	if (PREV.br_startoff == new->br_startoff)
+		state |= BMAP_LEFT_FILLING;
+	if (PREV.br_startoff + PREV.br_blockcount == new_endoff)
+		state |= BMAP_RIGHT_FILLING;
+
+	/*
+	 * Check and set flags if this segment has a left neighbor.
+	 * Don't set contiguous if the combined extent would be too large.
+	 */
+	if (xfs_iext_peek_prev_extent(ifp, icur, &LEFT)) {
+		state |= BMAP_LEFT_VALID;
+		if (isnullstartblock(LEFT.br_startblock))
+			state |= BMAP_LEFT_DELAY;
+	}
+
+	if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
+	    LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
+	    LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
+	    LEFT.br_state == new->br_state &&
+	    LEFT.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
+		state |= BMAP_LEFT_CONTIG;
+
+	/*
+	 * Check and set flags if this segment has a right neighbor.
+	 * Don't set contiguous if the combined extent would be too large.
+	 * Also check for all-three-contiguous being too large.
+	 */
+	if (xfs_iext_peek_next_extent(ifp, icur, &RIGHT)) {
+		state |= BMAP_RIGHT_VALID;
+		if (isnullstartblock(RIGHT.br_startblock))
+			state |= BMAP_RIGHT_DELAY;
+	}
+
+	if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
+	    new_endoff == RIGHT.br_startoff &&
+	    new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
+	    new->br_state == RIGHT.br_state &&
+	    new->br_blockcount + RIGHT.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
+	    ((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
+		       BMAP_RIGHT_FILLING)) !=
+		      (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
+		       BMAP_RIGHT_FILLING) ||
+	     LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
+			<= XFS_MAX_BMBT_EXTLEN))
+		state |= BMAP_RIGHT_CONTIG;
+
+	/*
+	 * Switch out based on the FILLING and CONTIG state bits.
+	 */
+	switch (state & (BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
+			 BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG)) {
+	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
+	     BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * The left and right neighbors are both contiguous with new.
+		 */
+		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
+
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &LEFT);
+		ifp->if_nextents -= 2;
+		if (cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, &RIGHT, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_delete(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_decrement(cur, 0, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_delete(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_decrement(cur, 0, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &LEFT);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * The left neighbor is contiguous, the right is not.
+		 */
+		LEFT.br_blockcount += PREV.br_blockcount;
+
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &LEFT);
+		ifp->if_nextents--;
+		if (cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, &PREV, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_delete(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_decrement(cur, 0, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &LEFT);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * The right neighbor is contiguous, the left is not.
+		 */
+		PREV.br_blockcount += RIGHT.br_blockcount;
+		PREV.br_state = new->br_state;
+
+		xfs_iext_next(ifp, icur);
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		ifp->if_nextents--;
+
+		if (cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, &RIGHT, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_delete(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_decrement(cur, 0, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &PREV);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
+		/*
+		 * Setting all of a previous oldext extent to newext.
+		 * Neither the left nor right neighbors are contiguous with
+		 * the new one.
+		 */
+		PREV.br_state = new->br_state;
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+
+		if (cur == NULL)
+			rval = XFS_ILOG_DEXT;
+		else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &PREV);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG:
+		/*
+		 * Setting the first part of a previous oldext extent to newext.
+		 * The left neighbor is contiguous.
+		 */
+		LEFT.br_blockcount += new->br_blockcount;
+
+		old = PREV;
+		PREV.br_startoff += new->br_blockcount;
+		PREV.br_startblock += new->br_blockcount;
+		PREV.br_blockcount -= new->br_blockcount;
+
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &LEFT);
+
+		if (cur == NULL)
+			rval = XFS_ILOG_DEXT;
+		else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &PREV);
+			if (error)
+				goto done;
+			error = xfs_btree_decrement(cur, 0, &i);
+			if (error)
+				goto done;
+			error = xfs_bmbt_update(cur, &LEFT);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_FILLING:
+		/*
+		 * Setting the first part of a previous oldext extent to newext.
+		 * The left neighbor is not contiguous.
+		 */
+		old = PREV;
+		PREV.br_startoff += new->br_blockcount;
+		PREV.br_startblock += new->br_blockcount;
+		PREV.br_blockcount -= new->br_blockcount;
+
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_insert(ip, icur, new, state);
+		ifp->if_nextents++;
+
+		if (cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &PREV);
+			if (error)
+				goto done;
+			cur->bc_rec.b = *new;
+			if ((error = xfs_btree_insert(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+		break;
+
+	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
+		/*
+		 * Setting the last part of a previous oldext extent to newext.
+		 * The right neighbor is contiguous with the new allocation.
+		 */
+		old = PREV;
+		PREV.br_blockcount -= new->br_blockcount;
+
+		RIGHT.br_startoff = new->br_startoff;
+		RIGHT.br_startblock = new->br_startblock;
+		RIGHT.br_blockcount += new->br_blockcount;
+
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &RIGHT);
+
+		if (cur == NULL)
+			rval = XFS_ILOG_DEXT;
+		else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &PREV);
+			if (error)
+				goto done;
+			error = xfs_btree_increment(cur, 0, &i);
+			if (error)
+				goto done;
+			error = xfs_bmbt_update(cur, &RIGHT);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_RIGHT_FILLING:
+		/*
+		 * Setting the last part of a previous oldext extent to newext.
+		 * The right neighbor is not contiguous.
+		 */
+		old = PREV;
+		PREV.br_blockcount -= new->br_blockcount;
+
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, new, state);
+		ifp->if_nextents++;
+
+		if (cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &PREV);
+			if (error)
+				goto done;
+			error = xfs_bmbt_lookup_eq(cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 0)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			if ((error = xfs_btree_insert(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+		break;
+
+	case 0:
+		/*
+		 * Setting the middle part of a previous oldext extent to
+		 * newext.  Contiguity is impossible here.
+		 * One extent becomes three extents.
+		 */
+		old = PREV;
+		PREV.br_blockcount = new->br_startoff - PREV.br_startoff;
+
+		r[0] = *new;
+		r[1].br_startoff = new_endoff;
+		r[1].br_blockcount =
+			old.br_startoff + old.br_blockcount - new_endoff;
+		r[1].br_startblock = new->br_startblock + new->br_blockcount;
+		r[1].br_state = PREV.br_state;
+
+		xfs_iext_update_extent(ip, state, icur, &PREV);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, &r[1], state);
+		xfs_iext_insert(ip, icur, &r[0], state);
+		ifp->if_nextents += 2;
+
+		if (cur == NULL)
+			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
+		else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			/* new right extent - oldext */
+			error = xfs_bmbt_update(cur, &r[1]);
+			if (error)
+				goto done;
+			/* new left extent - oldext */
+			cur->bc_rec.b = PREV;
+			if ((error = xfs_btree_insert(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto 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_bmbt_lookup_eq(cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 0)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			/* new middle extent - newext */
+			if ((error = xfs_btree_insert(cur, &i)))
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+		break;
+
+	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_CONTIG:
+	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
+	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+	case BMAP_LEFT_CONTIG:
+	case BMAP_RIGHT_CONTIG:
+		/*
+		 * These cases are all impossible.
+		 */
+		ASSERT(0);
+	}
+
+	/* update reverse mappings */
+	xfs_rmap_convert_extent(mp, tp, ip, whichfork, new);
+
+	/* convert to a btree if necessary */
+	if (xfs_bmap_needs_btree(ip, whichfork)) {
+		int	tmp_logflags;	/* partial log flag return val */
+
+		ASSERT(cur == NULL);
+		error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
+				&tmp_logflags, whichfork);
+		*logflagsp |= tmp_logflags;
+		if (error)
+			goto done;
+	}
+
+	/* clear out the allocated field, done with it now in any case. */
+	if (cur) {
+		cur->bc_ino.allocated = 0;
+		*curp = cur;
+	}
+
+	xfs_bmap_check_leaf_extents(*curp, ip, whichfork);
+done:
+	*logflagsp |= rval;
+	return error;
+#undef	LEFT
+#undef	RIGHT
+#undef	PREV
+}
+
+/*
+ * Convert a hole to a delayed allocation.
+ */
+STATIC void
+xfs_bmap_add_extent_hole_delay(
+	xfs_inode_t		*ip,	/* incore inode pointer */
+	int			whichfork,
+	struct xfs_iext_cursor	*icur,
+	xfs_bmbt_irec_t		*new)	/* new data to add to file extents */
+{
+	struct xfs_ifork	*ifp;	/* inode fork pointer */
+	xfs_bmbt_irec_t		left;	/* left neighbor extent entry */
+	xfs_filblks_t		newlen=0;	/* new indirect size */
+	xfs_filblks_t		oldlen=0;	/* old indirect size */
+	xfs_bmbt_irec_t		right;	/* right neighbor extent entry */
+	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
+	xfs_filblks_t		temp;	 /* temp for indirect calculations */
+
+	ifp = xfs_ifork_ptr(ip, whichfork);
+	ASSERT(isnullstartblock(new->br_startblock));
+
+	/*
+	 * Check and set flags if this segment has a left neighbor
+	 */
+	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
+		state |= BMAP_LEFT_VALID;
+		if (isnullstartblock(left.br_startblock))
+			state |= BMAP_LEFT_DELAY;
+	}
+
+	/*
+	 * Check and set flags if the current (right) segment exists.
+	 * If it doesn't exist, we're converting the hole at end-of-file.
+	 */
+	if (xfs_iext_get_extent(ifp, icur, &right)) {
+		state |= BMAP_RIGHT_VALID;
+		if (isnullstartblock(right.br_startblock))
+			state |= BMAP_RIGHT_DELAY;
+	}
+
+	/*
+	 * Set contiguity flags on the left and right neighbors.
+	 * Don't let extents get too large, even if the pieces are contiguous.
+	 */
+	if ((state & BMAP_LEFT_VALID) && (state & BMAP_LEFT_DELAY) &&
+	    left.br_startoff + left.br_blockcount == new->br_startoff &&
+	    left.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
+		state |= BMAP_LEFT_CONTIG;
+
+	if ((state & BMAP_RIGHT_VALID) && (state & BMAP_RIGHT_DELAY) &&
+	    new->br_startoff + new->br_blockcount == right.br_startoff &&
+	    new->br_blockcount + right.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
+	    (!(state & BMAP_LEFT_CONTIG) ||
+	     (left.br_blockcount + new->br_blockcount +
+	      right.br_blockcount <= XFS_MAX_BMBT_EXTLEN)))
+		state |= BMAP_RIGHT_CONTIG;
+
+	/*
+	 * Switch out based on the contiguity flags.
+	 */
+	switch (state & (BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG)) {
+	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+		/*
+		 * New allocation is contiguous with delayed allocations
+		 * on the left and on the right.
+		 * Merge all three into a single extent record.
+		 */
+		temp = left.br_blockcount + new->br_blockcount +
+			right.br_blockcount;
+
+		oldlen = startblockval(left.br_startblock) +
+			startblockval(new->br_startblock) +
+			startblockval(right.br_startblock);
+		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
+					 oldlen);
+		left.br_startblock = nullstartblock(newlen);
+		left.br_blockcount = temp;
+
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
+		break;
+
+	case BMAP_LEFT_CONTIG:
+		/*
+		 * New allocation is contiguous with a delayed allocation
+		 * on the left.
+		 * Merge the new allocation with the left neighbor.
+		 */
+		temp = left.br_blockcount + new->br_blockcount;
+
+		oldlen = startblockval(left.br_startblock) +
+			startblockval(new->br_startblock);
+		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
+					 oldlen);
+		left.br_blockcount = temp;
+		left.br_startblock = nullstartblock(newlen);
+
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
+		break;
+
+	case BMAP_RIGHT_CONTIG:
+		/*
+		 * New allocation is contiguous with a delayed allocation
+		 * on the right.
+		 * Merge the new allocation with the right neighbor.
+		 */
+		temp = new->br_blockcount + right.br_blockcount;
+		oldlen = startblockval(new->br_startblock) +
+			startblockval(right.br_startblock);
+		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
+					 oldlen);
+		right.br_startoff = new->br_startoff;
+		right.br_startblock = nullstartblock(newlen);
+		right.br_blockcount = temp;
+		xfs_iext_update_extent(ip, state, icur, &right);
+		break;
+
+	case 0:
+		/*
+		 * New allocation is not contiguous with another
+		 * delayed allocation.
+		 * Insert a new entry.
+		 */
+		oldlen = newlen = 0;
+		xfs_iext_insert(ip, icur, new, state);
+		break;
+	}
+	if (oldlen != newlen) {
+		ASSERT(oldlen > newlen);
+		xfs_mod_fdblocks(ip->i_mount, (int64_t)(oldlen - newlen),
+				 false);
+		/*
+		 * Nothing to do for disk quota accounting here.
+		 */
+		xfs_mod_delalloc(ip->i_mount, (int64_t)newlen - oldlen);
+	}
+}
+
+/*
+ * Convert a hole to a real allocation.
+ */
+STATIC int				/* error */
+xfs_bmap_add_extent_hole_real(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_iext_cursor	*icur,
+	struct xfs_btree_cur	**curp,
+	struct xfs_bmbt_irec	*new,
+	int			*logflagsp,
+	uint32_t		flags)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_btree_cur	*cur = *curp;
+	int			error;	/* error return value */
+	int			i;	/* temp state */
+	xfs_bmbt_irec_t		left;	/* left neighbor extent entry */
+	xfs_bmbt_irec_t		right;	/* right neighbor extent entry */
+	int			rval=0;	/* return value (logging flags) */
+	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
+	struct xfs_bmbt_irec	old;
+
+	ASSERT(!isnullstartblock(new->br_startblock));
+	ASSERT(!cur || !(cur->bc_ino.flags & XFS_BTCUR_BMBT_WASDEL));
+
+	XFS_STATS_INC(mp, xs_add_exlist);
+
+	/*
+	 * Check and set flags if this segment has a left neighbor.
+	 */
+	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
+		state |= BMAP_LEFT_VALID;
+		if (isnullstartblock(left.br_startblock))
+			state |= BMAP_LEFT_DELAY;
+	}
+
+	/*
+	 * Check and set flags if this segment has a current value.
+	 * Not true if we're inserting into the "hole" at eof.
+	 */
+	if (xfs_iext_get_extent(ifp, icur, &right)) {
+		state |= BMAP_RIGHT_VALID;
+		if (isnullstartblock(right.br_startblock))
+			state |= BMAP_RIGHT_DELAY;
+	}
+
+	/*
+	 * We're inserting a real allocation between "left" and "right".
+	 * Set the contiguity flags.  Don't let extents get too large.
+	 */
+	if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
+	    left.br_startoff + left.br_blockcount == new->br_startoff &&
+	    left.br_startblock + left.br_blockcount == new->br_startblock &&
+	    left.br_state == new->br_state &&
+	    left.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
+		state |= BMAP_LEFT_CONTIG;
+
+	if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
+	    new->br_startoff + new->br_blockcount == right.br_startoff &&
+	    new->br_startblock + new->br_blockcount == right.br_startblock &&
+	    new->br_state == right.br_state &&
+	    new->br_blockcount + right.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
+	    (!(state & BMAP_LEFT_CONTIG) ||
+	     left.br_blockcount + new->br_blockcount +
+	     right.br_blockcount <= XFS_MAX_BMBT_EXTLEN))
+		state |= BMAP_RIGHT_CONTIG;
+
+	error = 0;
+	/*
+	 * Select which case we're in here, and implement it.
+	 */
+	switch (state & (BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG)) {
+	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
+		/*
+		 * New allocation is contiguous with real allocations on the
+		 * left and on the right.
+		 * Merge all three into a single extent record.
+		 */
+		left.br_blockcount += new->br_blockcount + right.br_blockcount;
+
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
+		ifp->if_nextents--;
+
+		if (cur == NULL) {
+			rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
+		} else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, &right, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_delete(cur, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_decrement(cur, 0, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &left);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_LEFT_CONTIG:
+		/*
+		 * New allocation is contiguous with a real allocation
+		 * on the left.
+		 * Merge the new allocation with the left neighbor.
+		 */
+		old = left;
+		left.br_blockcount += new->br_blockcount;
+
+		xfs_iext_prev(ifp, icur);
+		xfs_iext_update_extent(ip, state, icur, &left);
+
+		if (cur == NULL) {
+			rval = xfs_ilog_fext(whichfork);
+		} else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &left);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case BMAP_RIGHT_CONTIG:
+		/*
+		 * New allocation is contiguous with a real allocation
+		 * on the right.
+		 * Merge the new allocation with the right neighbor.
+		 */
+		old = right;
+
+		right.br_startoff = new->br_startoff;
+		right.br_startblock = new->br_startblock;
+		right.br_blockcount += new->br_blockcount;
+		xfs_iext_update_extent(ip, state, icur, &right);
+
+		if (cur == NULL) {
+			rval = xfs_ilog_fext(whichfork);
+		} else {
+			rval = 0;
+			error = xfs_bmbt_lookup_eq(cur, &old, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_bmbt_update(cur, &right);
+			if (error)
+				goto done;
+		}
+		break;
+
+	case 0:
+		/*
+		 * New allocation is not contiguous with another
+		 * real allocation.
+		 * Insert a new entry.
+		 */
+		xfs_iext_insert(ip, icur, new, state);
+		ifp->if_nextents++;
+
+		if (cur == NULL) {
+			rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
+		} else {
+			rval = XFS_ILOG_CORE;
+			error = xfs_bmbt_lookup_eq(cur, new, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 0)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+			error = xfs_btree_insert(cur, &i);
+			if (error)
+				goto done;
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		}
+		break;
+	}
+
+	/* add reverse mapping unless caller opted out */
+	if (!(flags & XFS_BMAPI_NORMAP))
+		xfs_rmap_map_extent(tp, ip, whichfork, new);
+
+	/* convert to a btree if necessary */
+	if (xfs_bmap_needs_btree(ip, whichfork)) {
+		int	tmp_logflags;	/* partial log flag return val */
+
+		ASSERT(cur == NULL);
+		error = xfs_bmap_extents_to_btree(tp, ip, curp, 0,
+				&tmp_logflags, whichfork);
+		*logflagsp |= tmp_logflags;
+		cur = *curp;
+		if (error)
+			goto done;
+	}
+
+	/* clear out the allocated field, done with it now in any case. */
+	if (cur)
+		cur->bc_ino.allocated = 0;
+
+	xfs_bmap_check_leaf_extents(cur, ip, whichfork);
+done:
+	*logflagsp |= rval;
+	return error;
+}
+
+/*
+ * Functions used in the extent read, allocate and remove paths
+ */
+
+/*
+ * Adjust the size of the new extent based on i_extsize and rt extsize.
+ */
+int
+xfs_bmap_extsize_align(
+	xfs_mount_t	*mp,
+	xfs_bmbt_irec_t	*gotp,		/* next extent pointer */
+	xfs_bmbt_irec_t	*prevp,		/* previous extent pointer */
+	xfs_extlen_t	extsz,		/* align to this extent size */
+	int		rt,		/* is this a realtime inode? */
+	int		eof,		/* is extent at end-of-file? */
+	int		delay,		/* creating delalloc extent? */
+	int		convert,	/* overwriting unwritten extent? */
+	xfs_fileoff_t	*offp,		/* in/out: aligned offset */
+	xfs_extlen_t	*lenp)		/* in/out: aligned length */
+{
+	xfs_fileoff_t	orig_off;	/* original offset */
+	xfs_extlen_t	orig_alen;	/* original length */
+	xfs_fileoff_t	orig_end;	/* original off+len */
+	xfs_fileoff_t	nexto;		/* next file offset */
+	xfs_fileoff_t	prevo;		/* previous file offset */
+	xfs_fileoff_t	align_off;	/* temp for offset */
+	xfs_extlen_t	align_alen;	/* temp for length */
+	xfs_extlen_t	temp;		/* temp for calculations */
+
+	if (convert)
+		return 0;
+
+	orig_off = align_off = *offp;
+	orig_alen = align_alen = *lenp;
+	orig_end = orig_off + orig_alen;
+
+	/*
+	 * If this request overlaps an existing extent, then don't
+	 * attempt to perform any additional alignment.
+	 */
+	if (!delay && !eof &&
+	    (orig_off >= gotp->br_startoff) &&
+	    (orig_end <= gotp->br_startoff + gotp->br_blockcount)) {
+		return 0;
+	}
+
+	/*
+	 * If the file offset is unaligned vs. the extent size
+	 * we need to align it.  This will be possible unless
+	 * the file was previously written with a kernel that didn't
+	 * perform this alignment, or if a truncate shot us in the
+	 * foot.
+	 */
+	div_u64_rem(orig_off, extsz, &temp);
+	if (temp) {
+		align_alen += temp;
+		align_off -= temp;
+	}
+
+	/* Same adjustment for the end of the requested area. */
+	temp = (align_alen % extsz);
+	if (temp)
+		align_alen += extsz - temp;
+
+	/*
+	 * For large extent hint sizes, the aligned extent might be larger than
+	 * XFS_BMBT_MAX_EXTLEN. In that case, reduce the size by an extsz so
+	 * that it pulls the length back under XFS_BMBT_MAX_EXTLEN. The outer
+	 * allocation loops handle short allocation just fine, so it is safe to
+	 * do this. We only want to do it when we are forced to, though, because
+	 * it means more allocation operations are required.
+	 */
+	while (align_alen > XFS_MAX_BMBT_EXTLEN)
+		align_alen -= extsz;
+	ASSERT(align_alen <= XFS_MAX_BMBT_EXTLEN);
+
+	/*
+	 * If the previous block overlaps with this proposed allocation
+	 * then move the start forward without adjusting the length.
+	 */
+	if (prevp->br_startoff != NULLFILEOFF) {
+		if (prevp->br_startblock == HOLESTARTBLOCK)
+			prevo = prevp->br_startoff;
+		else
+			prevo = prevp->br_startoff + prevp->br_blockcount;
+	} else
+		prevo = 0;
+	if (align_off != orig_off && align_off < prevo)
+		align_off = prevo;
+	/*
+	 * If the next block overlaps with this proposed allocation
+	 * then move the start back without adjusting the length,
+	 * but not before offset 0.
+	 * This may of course make the start overlap previous block,
+	 * and if we hit the offset 0 limit then the next block
+	 * can still overlap too.
+	 */
+	if (!eof && gotp->br_startoff != NULLFILEOFF) {
+		if ((delay && gotp->br_startblock == HOLESTARTBLOCK) ||
+		    (!delay && gotp->br_startblock == DELAYSTARTBLOCK))
+			nexto = gotp->br_startoff + gotp->br_blockcount;
+		else
+			nexto = gotp->br_startoff;
+	} else
+		nexto = NULLFILEOFF;
+	if (!eof &&
+	    align_off + align_alen != orig_end &&
+	    align_off + align_alen > nexto)
+		align_off = nexto > align_alen ? nexto - align_alen : 0;
+	/*
+	 * If we're now overlapping the next or previous extent that
+	 * means we can't fit an extsz piece in this hole.  Just move
+	 * the start forward to the first valid spot and set
+	 * the length so we hit the end.
+	 */
+	if (align_off != orig_off && align_off < prevo)
+		align_off = prevo;
+	if (align_off + align_alen != orig_end &&
+	    align_off + align_alen > nexto &&
+	    nexto != NULLFILEOFF) {
+		ASSERT(nexto > prevo);
+		align_alen = nexto - align_off;
+	}
+
+	/*
+	 * If realtime, and the result isn't a multiple of the realtime
+	 * extent size we need to remove blocks until it is.
+	 */
+	if (rt && (temp = (align_alen % mp->m_sb.sb_rextsize))) {
+		/*
+		 * We're not covering the original request, or
+		 * we won't be able to once we fix the length.
+		 */
+		if (orig_off < align_off ||
+		    orig_end > align_off + align_alen ||
+		    align_alen - temp < orig_alen)
+			return -EINVAL;
+		/*
+		 * Try to fix it by moving the start up.
+		 */
+		if (align_off + temp <= orig_off) {
+			align_alen -= temp;
+			align_off += temp;
+		}
+		/*
+		 * Try to fix it by moving the end in.
+		 */
+		else if (align_off + align_alen - temp >= orig_end)
+			align_alen -= temp;
+		/*
+		 * Set the start to the minimum then trim the length.
+		 */
+		else {
+			align_alen -= orig_off - align_off;
+			align_off = orig_off;
+			align_alen -= align_alen % mp->m_sb.sb_rextsize;
+		}
+		/*
+		 * Result doesn't cover the request, fail it.
+		 */
+		if (orig_off < align_off || orig_end > align_off + align_alen)
+			return -EINVAL;
+	} else {
+		ASSERT(orig_off >= align_off);
+		/* see XFS_BMBT_MAX_EXTLEN handling above */
+		ASSERT(orig_end <= align_off + align_alen ||
+		       align_alen + extsz > XFS_MAX_BMBT_EXTLEN);
+	}
+
+#ifdef DEBUG
+	if (!eof && gotp->br_startoff != NULLFILEOFF)
+		ASSERT(align_off + align_alen <= gotp->br_startoff);
+	if (prevp->br_startoff != NULLFILEOFF)
+		ASSERT(align_off >= prevp->br_startoff + prevp->br_blockcount);
+#endif
+
+	*lenp = align_alen;
+	*offp = align_off;
+	return 0;
+}
+
+#define XFS_ALLOC_GAP_UNITS	4
+
+void
+xfs_bmap_adjacent(
+	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
+{
+	xfs_fsblock_t	adjust;		/* adjustment to block numbers */
+	xfs_mount_t	*mp;		/* mount point structure */
+	int		rt;		/* true if inode is realtime */
+
+#define	ISVALID(x,y)	\
+	(rt ? \
+		(x) < mp->m_sb.sb_rblocks : \
+		XFS_FSB_TO_AGNO(mp, x) == XFS_FSB_TO_AGNO(mp, y) && \
+		XFS_FSB_TO_AGNO(mp, x) < mp->m_sb.sb_agcount && \
+		XFS_FSB_TO_AGBNO(mp, x) < mp->m_sb.sb_agblocks)
+
+	mp = ap->ip->i_mount;
+	rt = XFS_IS_REALTIME_INODE(ap->ip) &&
+		(ap->datatype & XFS_ALLOC_USERDATA);
+	/*
+	 * If allocating at eof, and there's a previous real block,
+	 * try to use its last block as our starting point.
+	 */
+	if (ap->eof && ap->prev.br_startoff != NULLFILEOFF &&
+	    !isnullstartblock(ap->prev.br_startblock) &&
+	    ISVALID(ap->prev.br_startblock + ap->prev.br_blockcount,
+		    ap->prev.br_startblock)) {
+		ap->blkno = ap->prev.br_startblock + ap->prev.br_blockcount;
+		/*
+		 * Adjust for the gap between prevp and us.
+		 */
+		adjust = ap->offset -
+			(ap->prev.br_startoff + ap->prev.br_blockcount);
+		if (adjust &&
+		    ISVALID(ap->blkno + adjust, ap->prev.br_startblock))
+			ap->blkno += adjust;
+	}
+	/*
+	 * If not at eof, then compare the two neighbor blocks.
+	 * Figure out whether either one gives us a good starting point,
+	 * and pick the better one.
+	 */
+	else if (!ap->eof) {
+		xfs_fsblock_t	gotbno;		/* right side block number */
+		xfs_fsblock_t	gotdiff=0;	/* right side difference */
+		xfs_fsblock_t	prevbno;	/* left side block number */
+		xfs_fsblock_t	prevdiff=0;	/* left side difference */
+
+		/*
+		 * If there's a previous (left) block, select a requested
+		 * start block based on it.
+		 */
+		if (ap->prev.br_startoff != NULLFILEOFF &&
+		    !isnullstartblock(ap->prev.br_startblock) &&
+		    (prevbno = ap->prev.br_startblock +
+			       ap->prev.br_blockcount) &&
+		    ISVALID(prevbno, ap->prev.br_startblock)) {
+			/*
+			 * Calculate gap to end of previous block.
+			 */
+			adjust = prevdiff = ap->offset -
+				(ap->prev.br_startoff +
+				 ap->prev.br_blockcount);
+			/*
+			 * Figure the startblock based on the previous block's
+			 * end and the gap size.
+			 * Heuristic!
+			 * If the gap is large relative to the piece we're
+			 * allocating, or using it gives us an invalid block
+			 * number, then just use the end of the previous block.
+			 */
+			if (prevdiff <= XFS_ALLOC_GAP_UNITS * ap->length &&
+			    ISVALID(prevbno + prevdiff,
+				    ap->prev.br_startblock))
+				prevbno += adjust;
+			else
+				prevdiff += adjust;
+		}
+		/*
+		 * No previous block or can't follow it, just default.
+		 */
+		else
+			prevbno = NULLFSBLOCK;
+		/*
+		 * If there's a following (right) block, select a requested
+		 * start block based on it.
+		 */
+		if (!isnullstartblock(ap->got.br_startblock)) {
+			/*
+			 * Calculate gap to start of next block.
+			 */
+			adjust = gotdiff = ap->got.br_startoff - ap->offset;
+			/*
+			 * Figure the startblock based on the next block's
+			 * start and the gap size.
+			 */
+			gotbno = ap->got.br_startblock;
+			/*
+			 * Heuristic!
+			 * If the gap is large relative to the piece we're
+			 * allocating, or using it gives us an invalid block
+			 * number, then just use the start of the next block
+			 * offset by our length.
+			 */
+			if (gotdiff <= XFS_ALLOC_GAP_UNITS * ap->length &&
+			    ISVALID(gotbno - gotdiff, gotbno))
+				gotbno -= adjust;
+			else if (ISVALID(gotbno - ap->length, gotbno)) {
+				gotbno -= ap->length;
+				gotdiff += adjust - ap->length;
+			} else
+				gotdiff += adjust;
+		}
+		/*
+		 * No next block, just default.
+		 */
+		else
+			gotbno = NULLFSBLOCK;
+		/*
+		 * If both valid, pick the better one, else the only good
+		 * one, else ap->blkno is already set (to 0 or the inode block).
+		 */
+		if (prevbno != NULLFSBLOCK && gotbno != NULLFSBLOCK)
+			ap->blkno = prevdiff <= gotdiff ? prevbno : gotbno;
+		else if (prevbno != NULLFSBLOCK)
+			ap->blkno = prevbno;
+		else if (gotbno != NULLFSBLOCK)
+			ap->blkno = gotbno;
+	}
+#undef ISVALID
+}
+
+int
+xfs_bmap_longest_free_extent(
+	struct xfs_perag	*pag,
+	struct xfs_trans	*tp,
+	xfs_extlen_t		*blen)
+{
+	xfs_extlen_t		longest;
+	int			error = 0;
+
+	if (!xfs_perag_initialised_agf(pag)) {
+		error = xfs_alloc_read_agf(pag, tp, XFS_ALLOC_FLAG_TRYLOCK,
+				NULL);
+		if (error)
+			return error;
+	}
+
+	longest = xfs_alloc_longest_free_extent(pag,
+				xfs_alloc_min_freelist(pag->pag_mount, pag),
+				xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE));
+	if (*blen < longest)
+		*blen = longest;
+
+	return 0;
+}
+
+static xfs_extlen_t
+xfs_bmap_select_minlen(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	xfs_extlen_t		blen)
+{
+
+	/*
+	 * Since we used XFS_ALLOC_FLAG_TRYLOCK in _longest_free_extent(), it is
+	 * possible that there is enough contiguous free space for this request.
+	 */
+	if (blen < ap->minlen)
+		return ap->minlen;
+
+	/*
+	 * If the best seen length is less than the request length,
+	 * use the best as the minimum, otherwise we've got the maxlen we
+	 * were asked for.
+	 */
+	if (blen < args->maxlen)
+		return blen;
+	return args->maxlen;
+}
+
+static int
+xfs_bmap_btalloc_select_lengths(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	xfs_extlen_t		*blen)
+{
+	struct xfs_mount	*mp = args->mp;
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		agno, startag;
+	int			error = 0;
+
+	if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
+		args->total = ap->minlen;
+		args->minlen = ap->minlen;
+		return 0;
+	}
+
+	args->total = ap->total;
+	startag = XFS_FSB_TO_AGNO(mp, ap->blkno);
+	if (startag == NULLAGNUMBER)
+		startag = 0;
+
+	*blen = 0;
+	for_each_perag_wrap(mp, startag, agno, pag) {
+		error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
+		if (error && error != -EAGAIN)
+			break;
+		error = 0;
+		if (*blen >= args->maxlen)
+			break;
+	}
+	if (pag)
+		xfs_perag_rele(pag);
+
+	args->minlen = xfs_bmap_select_minlen(ap, args, *blen);
+	return error;
+}
+
+/* Update all inode and quota accounting for the allocation we just did. */
+static void
+xfs_bmap_btalloc_accounting(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args)
+{
+	if (ap->flags & XFS_BMAPI_COWFORK) {
+		/*
+		 * COW fork blocks are in-core only and thus are treated as
+		 * in-core quota reservation (like delalloc blocks) even when
+		 * converted to real blocks. The quota reservation is not
+		 * accounted to disk until blocks are remapped to the data
+		 * fork. So if these blocks were previously delalloc, we
+		 * already have quota reservation and there's nothing to do
+		 * yet.
+		 */
+		if (ap->wasdel) {
+			xfs_mod_delalloc(ap->ip->i_mount, -(int64_t)args->len);
+			return;
+		}
+
+		/*
+		 * Otherwise, we've allocated blocks in a hole. The transaction
+		 * has acquired in-core quota reservation for this extent.
+		 * Rather than account these as real blocks, however, we reduce
+		 * the transaction quota reservation based on the allocation.
+		 * This essentially transfers the transaction quota reservation
+		 * to that of a delalloc extent.
+		 */
+		ap->ip->i_delayed_blks += args->len;
+		xfs_trans_mod_dquot_byino(ap->tp, ap->ip, XFS_TRANS_DQ_RES_BLKS,
+				-(long)args->len);
+		return;
+	}
+
+	/* data/attr fork only */
+	ap->ip->i_nblocks += args->len;
+	xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
+	if (ap->wasdel) {
+		ap->ip->i_delayed_blks -= args->len;
+		xfs_mod_delalloc(ap->ip->i_mount, -(int64_t)args->len);
+	}
+	xfs_trans_mod_dquot_byino(ap->tp, ap->ip,
+		ap->wasdel ? XFS_TRANS_DQ_DELBCOUNT : XFS_TRANS_DQ_BCOUNT,
+		args->len);
+}
+
+static int
+xfs_bmap_compute_alignments(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args)
+{
+	struct xfs_mount	*mp = args->mp;
+	xfs_extlen_t		align = 0; /* minimum allocation alignment */
+	int			stripe_align = 0;
+
+	/* stripe alignment for allocation is determined by mount parameters */
+	if (mp->m_swidth && xfs_has_swalloc(mp))
+		stripe_align = mp->m_swidth;
+	else if (mp->m_dalign)
+		stripe_align = mp->m_dalign;
+
+	if (ap->flags & XFS_BMAPI_COWFORK)
+		align = xfs_get_cowextsz_hint(ap->ip);
+	else if (ap->datatype & XFS_ALLOC_USERDATA)
+		align = xfs_get_extsz_hint(ap->ip);
+	if (align) {
+		if (xfs_bmap_extsize_align(mp, &ap->got, &ap->prev, align, 0,
+					ap->eof, 0, ap->conv, &ap->offset,
+					&ap->length))
+			ASSERT(0);
+		ASSERT(ap->length);
+	}
+
+	/* apply extent size hints if obtained earlier */
+	if (align) {
+		args->prod = align;
+		div_u64_rem(ap->offset, args->prod, &args->mod);
+		if (args->mod)
+			args->mod = args->prod - args->mod;
+	} else if (mp->m_sb.sb_blocksize >= PAGE_SIZE) {
+		args->prod = 1;
+		args->mod = 0;
+	} else {
+		args->prod = PAGE_SIZE >> mp->m_sb.sb_blocklog;
+		div_u64_rem(ap->offset, args->prod, &args->mod);
+		if (args->mod)
+			args->mod = args->prod - args->mod;
+	}
+
+	return stripe_align;
+}
+
+static void
+xfs_bmap_process_allocated_extent(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	xfs_fileoff_t		orig_offset,
+	xfs_extlen_t		orig_length)
+{
+	ap->blkno = args->fsbno;
+	ap->length = args->len;
+	/*
+	 * If the extent size hint is active, we tried to round the
+	 * caller's allocation request offset down to extsz and the
+	 * length up to another extsz boundary.  If we found a free
+	 * extent we mapped it in starting at this new offset.  If the
+	 * newly mapped space isn't long enough to cover any of the
+	 * range of offsets that was originally requested, move the
+	 * mapping up so that we can fill as much of the caller's
+	 * original request as possible.  Free space is apparently
+	 * very fragmented so we're unlikely to be able to satisfy the
+	 * hints anyway.
+	 */
+	if (ap->length <= orig_length)
+		ap->offset = orig_offset;
+	else if (ap->offset + ap->length < orig_offset + orig_length)
+		ap->offset = orig_offset + orig_length - ap->length;
+	xfs_bmap_btalloc_accounting(ap, args);
+}
+
+#ifdef DEBUG
+static int
+xfs_bmap_exact_minlen_extent_alloc(
+	struct xfs_bmalloca	*ap)
+{
+	struct xfs_mount	*mp = ap->ip->i_mount;
+	struct xfs_alloc_arg	args = { .tp = ap->tp, .mp = mp };
+	xfs_fileoff_t		orig_offset;
+	xfs_extlen_t		orig_length;
+	int			error;
+
+	ASSERT(ap->length);
+
+	if (ap->minlen != 1) {
+		ap->blkno = NULLFSBLOCK;
+		ap->length = 0;
+		return 0;
+	}
+
+	orig_offset = ap->offset;
+	orig_length = ap->length;
+
+	args.alloc_minlen_only = 1;
+
+	xfs_bmap_compute_alignments(ap, &args);
+
+	/*
+	 * Unlike the longest extent available in an AG, we don't track
+	 * the length of an AG's shortest extent.
+	 * XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT is a debug only knob and
+	 * hence we can afford to start traversing from the 0th AG since
+	 * we need not be concerned about a drop in performance in
+	 * "debug only" code paths.
+	 */
+	ap->blkno = XFS_AGB_TO_FSB(mp, 0, 0);
+
+	args.oinfo = XFS_RMAP_OINFO_SKIP_UPDATE;
+	args.minlen = args.maxlen = ap->minlen;
+	args.total = ap->total;
+
+	args.alignment = 1;
+	args.minalignslop = 0;
+
+	args.minleft = ap->minleft;
+	args.wasdel = ap->wasdel;
+	args.resv = XFS_AG_RESV_NONE;
+	args.datatype = ap->datatype;
+
+	error = xfs_alloc_vextent_first_ag(&args, ap->blkno);
+	if (error)
+		return error;
+
+	if (args.fsbno != NULLFSBLOCK) {
+		xfs_bmap_process_allocated_extent(ap, &args, orig_offset,
+			orig_length);
+	} else {
+		ap->blkno = NULLFSBLOCK;
+		ap->length = 0;
+	}
+
+	return 0;
+}
+#else
+
+#define xfs_bmap_exact_minlen_extent_alloc(bma) (-EFSCORRUPTED)
+
+#endif
+
+/*
+ * If we are not low on available data blocks and we are allocating at
+ * EOF, optimise allocation for contiguous file extension and/or stripe
+ * alignment of the new extent.
+ *
+ * NOTE: ap->aeof is only set if the allocation length is >= the
+ * stripe unit and the allocation offset is at the end of file.
+ */
+static int
+xfs_bmap_btalloc_at_eof(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	xfs_extlen_t		blen,
+	int			stripe_align,
+	bool			ag_only)
+{
+	struct xfs_mount	*mp = args->mp;
+	struct xfs_perag	*caller_pag = args->pag;
+	int			error;
+
+	/*
+	 * If there are already extents in the file, try an exact EOF block
+	 * allocation to extend the file as a contiguous extent. If that fails,
+	 * or it's the first allocation in a file, just try for a stripe aligned
+	 * allocation.
+	 */
+	if (ap->offset) {
+		xfs_extlen_t	nextminlen = 0;
+
+		/*
+		 * Compute the minlen+alignment for the next case.  Set slop so
+		 * that the value of minlen+alignment+slop doesn't go up between
+		 * the calls.
+		 */
+		args->alignment = 1;
+		if (blen > stripe_align && blen <= args->maxlen)
+			nextminlen = blen - stripe_align;
+		else
+			nextminlen = args->minlen;
+		if (nextminlen + stripe_align > args->minlen + 1)
+			args->minalignslop = nextminlen + stripe_align -
+					args->minlen - 1;
+		else
+			args->minalignslop = 0;
+
+		if (!caller_pag)
+			args->pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, ap->blkno));
+		error = xfs_alloc_vextent_exact_bno(args, ap->blkno);
+		if (!caller_pag) {
+			xfs_perag_put(args->pag);
+			args->pag = NULL;
+		}
+		if (error)
+			return error;
+
+		if (args->fsbno != NULLFSBLOCK)
+			return 0;
+		/*
+		 * Exact allocation failed. Reset to try an aligned allocation
+		 * according to the original allocation specification.
+		 */
+		args->alignment = stripe_align;
+		args->minlen = nextminlen;
+		args->minalignslop = 0;
+	} else {
+		/*
+		 * Adjust minlen to try and preserve alignment if we
+		 * can't guarantee an aligned maxlen extent.
+		 */
+		args->alignment = stripe_align;
+		if (blen > args->alignment &&
+		    blen <= args->maxlen + args->alignment)
+			args->minlen = blen - args->alignment;
+		args->minalignslop = 0;
+	}
+
+	if (ag_only) {
+		error = xfs_alloc_vextent_near_bno(args, ap->blkno);
+	} else {
+		args->pag = NULL;
+		error = xfs_alloc_vextent_start_ag(args, ap->blkno);
+		ASSERT(args->pag == NULL);
+		args->pag = caller_pag;
+	}
+	if (error)
+		return error;
+
+	if (args->fsbno != NULLFSBLOCK)
+		return 0;
+
+	/*
+	 * Allocation failed, so turn return the allocation args to their
+	 * original non-aligned state so the caller can proceed on allocation
+	 * failure as if this function was never called.
+	 */
+	args->alignment = 1;
+	return 0;
+}
+
+/*
+ * We have failed multiple allocation attempts so now are in a low space
+ * allocation situation. Try a locality first full filesystem minimum length
+ * allocation whilst still maintaining necessary total block reservation
+ * requirements.
+ *
+ * If that fails, we are now critically low on space, so perform a last resort
+ * allocation attempt: no reserve, no locality, blocking, minimum length, full
+ * filesystem free space scan. We also indicate to future allocations in this
+ * transaction that we are critically low on space so they don't waste time on
+ * allocation modes that are unlikely to succeed.
+ */
+int
+xfs_bmap_btalloc_low_space(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args)
+{
+	int			error;
+
+	if (args->minlen > ap->minlen) {
+		args->minlen = ap->minlen;
+		error = xfs_alloc_vextent_start_ag(args, ap->blkno);
+		if (error || args->fsbno != NULLFSBLOCK)
+			return error;
+	}
+
+	/* Last ditch attempt before failure is declared. */
+	args->total = ap->minlen;
+	error = xfs_alloc_vextent_first_ag(args, 0);
+	if (error)
+		return error;
+	ap->tp->t_flags |= XFS_TRANS_LOWMODE;
+	return 0;
+}
+
+static int
+xfs_bmap_btalloc_filestreams(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	int			stripe_align)
+{
+	xfs_extlen_t		blen = 0;
+	int			error = 0;
+
+
+	error = xfs_filestream_select_ag(ap, args, &blen);
+	if (error)
+		return error;
+	ASSERT(args->pag);
+
+	/*
+	 * If we are in low space mode, then optimal allocation will fail so
+	 * prepare for minimal allocation and jump to the low space algorithm
+	 * immediately.
+	 */
+	if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
+		args->minlen = ap->minlen;
+		ASSERT(args->fsbno == NULLFSBLOCK);
+		goto out_low_space;
+	}
+
+	args->minlen = xfs_bmap_select_minlen(ap, args, blen);
+	if (ap->aeof)
+		error = xfs_bmap_btalloc_at_eof(ap, args, blen, stripe_align,
+				true);
+
+	if (!error && args->fsbno == NULLFSBLOCK)
+		error = xfs_alloc_vextent_near_bno(args, ap->blkno);
+
+out_low_space:
+	/*
+	 * We are now done with the perag reference for the filestreams
+	 * association provided by xfs_filestream_select_ag(). Release it now as
+	 * we've either succeeded, had a fatal error or we are out of space and
+	 * need to do a full filesystem scan for free space which will take it's
+	 * own references.
+	 */
+	xfs_perag_rele(args->pag);
+	args->pag = NULL;
+	if (error || args->fsbno != NULLFSBLOCK)
+		return error;
+
+	return xfs_bmap_btalloc_low_space(ap, args);
+}
+
+static int
+xfs_bmap_btalloc_best_length(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args,
+	int			stripe_align)
+{
+	xfs_extlen_t		blen = 0;
+	int			error;
+
+	ap->blkno = XFS_INO_TO_FSB(args->mp, ap->ip->i_ino);
+	xfs_bmap_adjacent(ap);
+
+	/*
+	 * Search for an allocation group with a single extent large enough for
+	 * the request.  If one isn't found, then adjust the minimum allocation
+	 * size to the largest space found.
+	 */
+	error = xfs_bmap_btalloc_select_lengths(ap, args, &blen);
+	if (error)
+		return error;
+
+	/*
+	 * Don't attempt optimal EOF allocation if previous allocations barely
+	 * succeeded due to being near ENOSPC. It is highly unlikely we'll get
+	 * optimal or even aligned allocations in this case, so don't waste time
+	 * trying.
+	 */
+	if (ap->aeof && !(ap->tp->t_flags & XFS_TRANS_LOWMODE)) {
+		error = xfs_bmap_btalloc_at_eof(ap, args, blen, stripe_align,
+				false);
+		if (error || args->fsbno != NULLFSBLOCK)
+			return error;
+	}
+
+	error = xfs_alloc_vextent_start_ag(args, ap->blkno);
+	if (error || args->fsbno != NULLFSBLOCK)
+		return error;
+
+	return xfs_bmap_btalloc_low_space(ap, args);
+}
+
+static int
+xfs_bmap_btalloc(
+	struct xfs_bmalloca	*ap)
+{
+	struct xfs_mount	*mp = ap->ip->i_mount;
+	struct xfs_alloc_arg	args = {
+		.tp		= ap->tp,
+		.mp		= mp,
+		.fsbno		= NULLFSBLOCK,
+		.oinfo		= XFS_RMAP_OINFO_SKIP_UPDATE,
+		.minleft	= ap->minleft,
+		.wasdel		= ap->wasdel,
+		.resv		= XFS_AG_RESV_NONE,
+		.datatype	= ap->datatype,
+		.alignment	= 1,
+		.minalignslop	= 0,
+	};
+	xfs_fileoff_t		orig_offset;
+	xfs_extlen_t		orig_length;
+	int			error;
+	int			stripe_align;
+
+	ASSERT(ap->length);
+	orig_offset = ap->offset;
+	orig_length = ap->length;
+
+	stripe_align = xfs_bmap_compute_alignments(ap, &args);
+
+	/* Trim the allocation back to the maximum an AG can fit. */
+	args.maxlen = min(ap->length, mp->m_ag_max_usable);
+
+	if ((ap->datatype & XFS_ALLOC_USERDATA) &&
+	    xfs_inode_is_filestream(ap->ip))
+		error = xfs_bmap_btalloc_filestreams(ap, &args, stripe_align);
+	else
+		error = xfs_bmap_btalloc_best_length(ap, &args, stripe_align);
+	if (error)
+		return error;
+
+	if (args.fsbno != NULLFSBLOCK) {
+		xfs_bmap_process_allocated_extent(ap, &args, orig_offset,
+			orig_length);
+	} else {
+		ap->blkno = NULLFSBLOCK;
+		ap->length = 0;
+	}
+	return 0;
+}
+
+/* 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
+ */
+STATIC void
+xfs_bmapi_trim_map(
+	struct xfs_bmbt_irec	*mval,
+	struct xfs_bmbt_irec	*got,
+	xfs_fileoff_t		*bno,
+	xfs_filblks_t		len,
+	xfs_fileoff_t		obno,
+	xfs_fileoff_t		end,
+	int			n,
+	uint32_t		flags)
+{
+	if ((flags & XFS_BMAPI_ENTIRE) ||
+	    got->br_startoff + got->br_blockcount <= obno) {
+		*mval = *got;
+		if (isnullstartblock(got->br_startblock))
+			mval->br_startblock = DELAYSTARTBLOCK;
+		return;
+	}
+
+	if (obno > *bno)
+		*bno = obno;
+	ASSERT((*bno >= obno) || (n == 0));
+	ASSERT(*bno < end);
+	mval->br_startoff = *bno;
+	if (isnullstartblock(got->br_startblock))
+		mval->br_startblock = DELAYSTARTBLOCK;
+	else
+		mval->br_startblock = got->br_startblock +
+					(*bno - got->br_startoff);
+	/*
+	 * Return the minimum of what we got and what we asked for for
+	 * the length.  We can use the len variable here because it is
+	 * modified below and we could have been there before coming
+	 * here if the first part of the allocation didn't overlap what
+	 * was asked for.
+	 */
+	mval->br_blockcount = XFS_FILBLKS_MIN(end - *bno,
+			got->br_blockcount - (*bno - got->br_startoff));
+	mval->br_state = got->br_state;
+	ASSERT(mval->br_blockcount <= len);
+	return;
+}
+
+/*
+ * Update and validate the extent map to return
+ */
+STATIC void
+xfs_bmapi_update_map(
+	struct xfs_bmbt_irec	**map,
+	xfs_fileoff_t		*bno,
+	xfs_filblks_t		*len,
+	xfs_fileoff_t		obno,
+	xfs_fileoff_t		end,
+	int			*n,
+	uint32_t		flags)
+{
+	xfs_bmbt_irec_t	*mval = *map;
+
+	ASSERT((flags & XFS_BMAPI_ENTIRE) ||
+	       ((mval->br_startoff + mval->br_blockcount) <= end));
+	ASSERT((flags & XFS_BMAPI_ENTIRE) || (mval->br_blockcount <= *len) ||
+	       (mval->br_startoff < obno));
+
+	*bno = mval->br_startoff + mval->br_blockcount;
+	*len = end - *bno;
+	if (*n > 0 && mval->br_startoff == mval[-1].br_startoff) {
+		/* update previous map with new information */
+		ASSERT(mval->br_startblock == mval[-1].br_startblock);
+		ASSERT(mval->br_blockcount > mval[-1].br_blockcount);
+		ASSERT(mval->br_state == mval[-1].br_state);
+		mval[-1].br_blockcount = mval->br_blockcount;
+		mval[-1].br_state = mval->br_state;
+	} else if (*n > 0 && mval->br_startblock != DELAYSTARTBLOCK &&
+		   mval[-1].br_startblock != DELAYSTARTBLOCK &&
+		   mval[-1].br_startblock != HOLESTARTBLOCK &&
+		   mval->br_startblock == mval[-1].br_startblock +
+					  mval[-1].br_blockcount &&
+		   mval[-1].br_state == mval->br_state) {
+		ASSERT(mval->br_startoff ==
+		       mval[-1].br_startoff + mval[-1].br_blockcount);
+		mval[-1].br_blockcount += mval->br_blockcount;
+	} else if (*n > 0 &&
+		   mval->br_startblock == DELAYSTARTBLOCK &&
+		   mval[-1].br_startblock == DELAYSTARTBLOCK &&
+		   mval->br_startoff ==
+		   mval[-1].br_startoff + mval[-1].br_blockcount) {
+		mval[-1].br_blockcount += mval->br_blockcount;
+		mval[-1].br_state = mval->br_state;
+	} else if (!((*n == 0) &&
+		     ((mval->br_startoff + mval->br_blockcount) <=
+		      obno))) {
+		mval++;
+		(*n)++;
+	}
+	*map = mval;
+}
+
+/*
+ * Map file blocks to filesystem blocks without allocation.
+ */
+int
+xfs_bmapi_read(
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		bno,
+	xfs_filblks_t		len,
+	struct xfs_bmbt_irec	*mval,
+	int			*nmap,
+	uint32_t		flags)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	int			whichfork = xfs_bmapi_whichfork(flags);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_bmbt_irec	got;
+	xfs_fileoff_t		obno;
+	xfs_fileoff_t		end;
+	struct xfs_iext_cursor	icur;
+	int			error;
+	bool			eof = false;
+	int			n = 0;
+
+	ASSERT(*nmap >= 1);
+	ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_ENTIRE)));
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED|XFS_ILOCK_EXCL));
+
+	if (WARN_ON_ONCE(!ifp))
+		return -EFSCORRUPTED;
+
+	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
+	    XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT))
+		return -EFSCORRUPTED;
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	XFS_STATS_INC(mp, xs_blk_mapr);
+
+	error = xfs_iread_extents(NULL, ip, whichfork);
+	if (error)
+		return error;
+
+	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got))
+		eof = true;
+	end = bno + len;
+	obno = bno;
+
+	while (bno < end && n < *nmap) {
+		/* Reading past eof, act as though there's a hole up to end. */
+		if (eof)
+			got.br_startoff = end;
+		if (got.br_startoff > bno) {
+			/* Reading in a hole.  */
+			mval->br_startoff = bno;
+			mval->br_startblock = HOLESTARTBLOCK;
+			mval->br_blockcount =
+				XFS_FILBLKS_MIN(len, got.br_startoff - bno);
+			mval->br_state = XFS_EXT_NORM;
+			bno += mval->br_blockcount;
+			len -= mval->br_blockcount;
+			mval++;
+			n++;
+			continue;
+		}
+
+		/* set up the extent map to return. */
+		xfs_bmapi_trim_map(mval, &got, &bno, len, obno, end, n, flags);
+		xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);
+
+		/* If we're done, stop now. */
+		if (bno >= end || n >= *nmap)
+			break;
+
+		/* Else go on to the next record. */
+		if (!xfs_iext_next_extent(ifp, &icur, &got))
+			eof = true;
+	}
+	*nmap = n;
+	return 0;
+}
+
+/*
+ * Add a delayed allocation extent to an inode. Blocks are reserved from the
+ * global pool and the extent inserted into the inode in-core extent tree.
+ *
+ * On entry, got refers to the first extent beyond the offset of the extent to
+ * allocate or eof is specified if no such extent exists. On return, got refers
+ * to the extent record that was inserted to the inode fork.
+ *
+ * Note that the allocated extent may have been merged with contiguous extents
+ * during insertion into the inode fork. Thus, got does not reflect the current
+ * state of the inode fork on return. If necessary, the caller can use lastx to
+ * look up the updated record in the inode fork.
+ */
+int
+xfs_bmapi_reserve_delalloc(
+	struct xfs_inode	*ip,
+	int			whichfork,
+	xfs_fileoff_t		off,
+	xfs_filblks_t		len,
+	xfs_filblks_t		prealloc,
+	struct xfs_bmbt_irec	*got,
+	struct xfs_iext_cursor	*icur,
+	int			eof)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	xfs_extlen_t		alen;
+	xfs_extlen_t		indlen;
+	int			error;
+	xfs_fileoff_t		aoff = off;
+
+	/*
+	 * Cap the alloc length. Keep track of prealloc so we know whether to
+	 * tag the inode before we return.
+	 */
+	alen = XFS_FILBLKS_MIN(len + prealloc, XFS_MAX_BMBT_EXTLEN);
+	if (!eof)
+		alen = XFS_FILBLKS_MIN(alen, got->br_startoff - aoff);
+	if (prealloc && alen >= len)
+		prealloc = alen - len;
+
+	/* Figure out the extent size, adjust alen */
+	if (whichfork == XFS_COW_FORK) {
+		struct xfs_bmbt_irec	prev;
+		xfs_extlen_t		extsz = xfs_get_cowextsz_hint(ip);
+
+		if (!xfs_iext_peek_prev_extent(ifp, icur, &prev))
+			prev.br_startoff = NULLFILEOFF;
+
+		error = xfs_bmap_extsize_align(mp, got, &prev, extsz, 0, eof,
+					       1, 0, &aoff, &alen);
+		ASSERT(!error);
+	}
+
+	/*
+	 * Make a transaction-less quota reservation for delayed allocation
+	 * blocks.  This number gets adjusted later.  We return if we haven't
+	 * allocated blocks already inside this loop.
+	 */
+	error = xfs_quota_reserve_blkres(ip, alen);
+	if (error)
+		return error;
+
+	/*
+	 * Split changing sb for alen and indlen since they could be coming
+	 * from different places.
+	 */
+	indlen = (xfs_extlen_t)xfs_bmap_worst_indlen(ip, alen);
+	ASSERT(indlen > 0);
+
+	error = xfs_mod_fdblocks(mp, -((int64_t)alen), false);
+	if (error)
+		goto out_unreserve_quota;
+
+	error = xfs_mod_fdblocks(mp, -((int64_t)indlen), false);
+	if (error)
+		goto out_unreserve_blocks;
+
+
+	ip->i_delayed_blks += alen;
+	xfs_mod_delalloc(ip->i_mount, alen + indlen);
+
+	got->br_startoff = aoff;
+	got->br_startblock = nullstartblock(indlen);
+	got->br_blockcount = alen;
+	got->br_state = XFS_EXT_NORM;
+
+	xfs_bmap_add_extent_hole_delay(ip, whichfork, icur, got);
+
+	/*
+	 * Tag the inode if blocks were preallocated. Note that COW fork
+	 * preallocation can occur at the start or end of the extent, even when
+	 * prealloc == 0, so we must also check the aligned offset and length.
+	 */
+	if (whichfork == XFS_DATA_FORK && prealloc)
+		xfs_inode_set_eofblocks_tag(ip);
+	if (whichfork == XFS_COW_FORK && (prealloc || aoff < off || alen > len))
+		xfs_inode_set_cowblocks_tag(ip);
+
+	return 0;
+
+out_unreserve_blocks:
+	xfs_mod_fdblocks(mp, alen, false);
+out_unreserve_quota:
+	if (XFS_IS_QUOTA_ON(mp))
+		xfs_quota_unreserve_blkres(ip, alen);
+	return error;
+}
+
+static int
+xfs_bmap_alloc_userdata(
+	struct xfs_bmalloca	*bma)
+{
+	struct xfs_mount	*mp = bma->ip->i_mount;
+	int			whichfork = xfs_bmapi_whichfork(bma->flags);
+	int			error;
+
+	/*
+	 * Set the data type being allocated. For the data fork, the first data
+	 * in the file is treated differently to all other allocations. For the
+	 * attribute fork, we only need to ensure the allocated range is not on
+	 * the busy list.
+	 */
+	bma->datatype = XFS_ALLOC_NOBUSY;
+	if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK) {
+		bma->datatype |= XFS_ALLOC_USERDATA;
+		if (bma->offset == 0)
+			bma->datatype |= XFS_ALLOC_INITIAL_USER_DATA;
+
+		if (mp->m_dalign && bma->length >= mp->m_dalign) {
+			error = xfs_bmap_isaeof(bma, whichfork);
+			if (error)
+				return error;
+		}
+
+		if (XFS_IS_REALTIME_INODE(bma->ip))
+			return xfs_bmap_rtalloc(bma);
+	}
+
+	if (unlikely(XFS_TEST_ERROR(false, mp,
+			XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
+		return xfs_bmap_exact_minlen_extent_alloc(bma);
+
+	return xfs_bmap_btalloc(bma);
+}
+
+static int
+xfs_bmapi_allocate(
+	struct xfs_bmalloca	*bma)
+{
+	struct xfs_mount	*mp = bma->ip->i_mount;
+	int			whichfork = xfs_bmapi_whichfork(bma->flags);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
+	int			tmp_logflags = 0;
+	int			error;
+
+	ASSERT(bma->length > 0);
+
+	/*
+	 * For the wasdelay case, we could also just allocate the stuff asked
+	 * for in this bmap call but that wouldn't be as good.
+	 */
+	if (bma->wasdel) {
+		bma->length = (xfs_extlen_t)bma->got.br_blockcount;
+		bma->offset = bma->got.br_startoff;
+		if (!xfs_iext_peek_prev_extent(ifp, &bma->icur, &bma->prev))
+			bma->prev.br_startoff = NULLFILEOFF;
+	} else {
+		bma->length = XFS_FILBLKS_MIN(bma->length, XFS_MAX_BMBT_EXTLEN);
+		if (!bma->eof)
+			bma->length = XFS_FILBLKS_MIN(bma->length,
+					bma->got.br_startoff - bma->offset);
+	}
+
+	if (bma->flags & XFS_BMAPI_CONTIG)
+		bma->minlen = bma->length;
+	else
+		bma->minlen = 1;
+
+	if (bma->flags & XFS_BMAPI_METADATA) {
+		if (unlikely(XFS_TEST_ERROR(false, mp,
+				XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT)))
+			error = xfs_bmap_exact_minlen_extent_alloc(bma);
+		else
+			error = xfs_bmap_btalloc(bma);
+	} else {
+		error = xfs_bmap_alloc_userdata(bma);
+	}
+	if (error || bma->blkno == NULLFSBLOCK)
+		return error;
+
+	if (bma->flags & XFS_BMAPI_ZERO) {
+		error = xfs_zero_extent(bma->ip, bma->blkno, bma->length);
+		if (error)
+			return error;
+	}
+
+	if (ifp->if_format == XFS_DINODE_FMT_BTREE && !bma->cur)
+		bma->cur = xfs_bmbt_init_cursor(mp, bma->tp, bma->ip, whichfork);
+	/*
+	 * Bump the number of extents we've allocated
+	 * in this call.
+	 */
+	bma->nallocs++;
+
+	if (bma->cur)
+		bma->cur->bc_ino.flags =
+			bma->wasdel ? XFS_BTCUR_BMBT_WASDEL : 0;
+
+	bma->got.br_startoff = bma->offset;
+	bma->got.br_startblock = bma->blkno;
+	bma->got.br_blockcount = bma->length;
+	bma->got.br_state = XFS_EXT_NORM;
+
+	if (bma->flags & XFS_BMAPI_PREALLOC)
+		bma->got.br_state = XFS_EXT_UNWRITTEN;
+
+	if (bma->wasdel)
+		error = xfs_bmap_add_extent_delay_real(bma, whichfork);
+	else
+		error = xfs_bmap_add_extent_hole_real(bma->tp, bma->ip,
+				whichfork, &bma->icur, &bma->cur, &bma->got,
+				&bma->logflags, bma->flags);
+
+	bma->logflags |= tmp_logflags;
+	if (error)
+		return error;
+
+	/*
+	 * Update our extent pointer, given that xfs_bmap_add_extent_delay_real
+	 * or xfs_bmap_add_extent_hole_real might have merged it into one of
+	 * the neighbouring ones.
+	 */
+	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
+
+	ASSERT(bma->got.br_startoff <= bma->offset);
+	ASSERT(bma->got.br_startoff + bma->got.br_blockcount >=
+	       bma->offset + bma->length);
+	ASSERT(bma->got.br_state == XFS_EXT_NORM ||
+	       bma->got.br_state == XFS_EXT_UNWRITTEN);
+	return 0;
+}
+
+STATIC int
+xfs_bmapi_convert_unwritten(
+	struct xfs_bmalloca	*bma,
+	struct xfs_bmbt_irec	*mval,
+	xfs_filblks_t		len,
+	uint32_t		flags)
+{
+	int			whichfork = xfs_bmapi_whichfork(flags);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
+	int			tmp_logflags = 0;
+	int			error;
+
+	/* check if we need to do unwritten->real conversion */
+	if (mval->br_state == XFS_EXT_UNWRITTEN &&
+	    (flags & XFS_BMAPI_PREALLOC))
+		return 0;
+
+	/* check if we need to do real->unwritten conversion */
+	if (mval->br_state == XFS_EXT_NORM &&
+	    (flags & (XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT)) !=
+			(XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT))
+		return 0;
+
+	/*
+	 * Modify (by adding) the state flag, if writing.
+	 */
+	ASSERT(mval->br_blockcount <= len);
+	if (ifp->if_format == XFS_DINODE_FMT_BTREE && !bma->cur) {
+		bma->cur = xfs_bmbt_init_cursor(bma->ip->i_mount, bma->tp,
+					bma->ip, whichfork);
+	}
+	mval->br_state = (mval->br_state == XFS_EXT_UNWRITTEN)
+				? XFS_EXT_NORM : XFS_EXT_UNWRITTEN;
+
+	/*
+	 * Before insertion into the bmbt, zero the range being converted
+	 * if required.
+	 */
+	if (flags & XFS_BMAPI_ZERO) {
+		error = xfs_zero_extent(bma->ip, mval->br_startblock,
+					mval->br_blockcount);
+		if (error)
+			return error;
+	}
+
+	error = xfs_bmap_add_extent_unwritten_real(bma->tp, bma->ip, whichfork,
+			&bma->icur, &bma->cur, mval, &tmp_logflags);
+	/*
+	 * Log the inode core unconditionally in the unwritten extent conversion
+	 * path because the conversion might not have done so (e.g., if the
+	 * extent count hasn't changed). We need to make sure the inode is dirty
+	 * in the transaction for the sake of fsync(), even if nothing has
+	 * changed, because fsync() will not force the log for this transaction
+	 * unless it sees the inode pinned.
+	 *
+	 * Note: If we're only converting cow fork extents, there aren't
+	 * any on-disk updates to make, so we don't need to log anything.
+	 */
+	if (whichfork != XFS_COW_FORK)
+		bma->logflags |= tmp_logflags | XFS_ILOG_CORE;
+	if (error)
+		return error;
+
+	/*
+	 * Update our extent pointer, given that
+	 * xfs_bmap_add_extent_unwritten_real might have merged it into one
+	 * of the neighbouring ones.
+	 */
+	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
+
+	/*
+	 * We may have combined previously unwritten space with written space,
+	 * so generate another request.
+	 */
+	if (mval->br_blockcount < len)
+		return -EAGAIN;
+	return 0;
+}
+
+xfs_extlen_t
+xfs_bmapi_minleft(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	int			fork)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, fork);
+
+	if (tp && tp->t_highest_agno != NULLAGNUMBER)
+		return 0;
+	if (ifp->if_format != XFS_DINODE_FMT_BTREE)
+		return 1;
+	return be16_to_cpu(ifp->if_broot->bb_level) + 1;
+}
+
+/*
+ * Log whatever the flags say, even if error.  Otherwise we might miss detecting
+ * a case where the data is changed, there's an error, and it's not logged so we
+ * don't shutdown when we should.  Don't bother logging extents/btree changes if
+ * we converted to the other format.
+ */
+static void
+xfs_bmapi_finish(
+	struct xfs_bmalloca	*bma,
+	int			whichfork,
+	int			error)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
+
+	if ((bma->logflags & xfs_ilog_fext(whichfork)) &&
+	    ifp->if_format != XFS_DINODE_FMT_EXTENTS)
+		bma->logflags &= ~xfs_ilog_fext(whichfork);
+	else if ((bma->logflags & xfs_ilog_fbroot(whichfork)) &&
+		 ifp->if_format != XFS_DINODE_FMT_BTREE)
+		bma->logflags &= ~xfs_ilog_fbroot(whichfork);
+
+	if (bma->logflags)
+		xfs_trans_log_inode(bma->tp, bma->ip, bma->logflags);
+	if (bma->cur)
+		xfs_btree_del_cursor(bma->cur, error);
+}
+
+/*
+ * Map file blocks to filesystem blocks, and allocate blocks or convert the
+ * extent state if necessary.  Details behaviour is controlled by the flags
+ * parameter.  Only allocates blocks from a single allocation group, to avoid
+ * locking problems.
+ */
+int
+xfs_bmapi_write(
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* incore inode */
+	xfs_fileoff_t		bno,		/* starting file offs. mapped */
+	xfs_filblks_t		len,		/* length to map in file */
+	uint32_t		flags,		/* XFS_BMAPI_... */
+	xfs_extlen_t		total,		/* total blocks needed */
+	struct xfs_bmbt_irec	*mval,		/* output: map values */
+	int			*nmap)		/* i/o: mval size/count */
+{
+	struct xfs_bmalloca	bma = {
+		.tp		= tp,
+		.ip		= ip,
+		.total		= total,
+	};
+	struct xfs_mount	*mp = ip->i_mount;
+	int			whichfork = xfs_bmapi_whichfork(flags);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	xfs_fileoff_t		end;		/* end of mapped file region */
+	bool			eof = false;	/* after the end of extents */
+	int			error;		/* error return */
+	int			n;		/* current extent index */
+	xfs_fileoff_t		obno;		/* old block number (offset) */
+
+#ifdef DEBUG
+	xfs_fileoff_t		orig_bno;	/* original block number value */
+	int			orig_flags;	/* original flags arg value */
+	xfs_filblks_t		orig_len;	/* original value of len arg */
+	struct xfs_bmbt_irec	*orig_mval;	/* original value of mval */
+	int			orig_nmap;	/* original value of *nmap */
+
+	orig_bno = bno;
+	orig_len = len;
+	orig_flags = flags;
+	orig_mval = mval;
+	orig_nmap = *nmap;
+#endif
+
+	ASSERT(*nmap >= 1);
+	ASSERT(*nmap <= XFS_BMAP_MAX_NMAP);
+	ASSERT(tp != NULL);
+	ASSERT(len > 0);
+	ASSERT(ifp->if_format != XFS_DINODE_FMT_LOCAL);
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	ASSERT(!(flags & XFS_BMAPI_REMAP));
+
+	/* zeroing is for currently only for data extents, not metadata */
+	ASSERT((flags & (XFS_BMAPI_METADATA | XFS_BMAPI_ZERO)) !=
+			(XFS_BMAPI_METADATA | XFS_BMAPI_ZERO));
+	/*
+	 * we can allocate unwritten extents or pre-zero allocated blocks,
+	 * but it makes no sense to do both at once. This would result in
+	 * zeroing the unwritten extent twice, but it still being an
+	 * unwritten extent....
+	 */
+	ASSERT((flags & (XFS_BMAPI_PREALLOC | XFS_BMAPI_ZERO)) !=
+			(XFS_BMAPI_PREALLOC | XFS_BMAPI_ZERO));
+
+	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
+	    XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) {
+		return -EFSCORRUPTED;
+	}
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	XFS_STATS_INC(mp, xs_blk_mapw);
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		goto error0;
+
+	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.icur, &bma.got))
+		eof = true;
+	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
+		bma.prev.br_startoff = NULLFILEOFF;
+	bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);
+
+	n = 0;
+	end = bno + len;
+	obno = bno;
+	while (bno < end && n < *nmap) {
+		bool			need_alloc = false, wasdelay = false;
+
+		/* in hole or beyond EOF? */
+		if (eof || bma.got.br_startoff > bno) {
+			/*
+			 * CoW fork conversions should /never/ hit EOF or
+			 * holes.  There should always be something for us
+			 * to work on.
+			 */
+			ASSERT(!((flags & XFS_BMAPI_CONVERT) &&
+			         (flags & XFS_BMAPI_COWFORK)));
+
+			need_alloc = true;
+		} else if (isnullstartblock(bma.got.br_startblock)) {
+			wasdelay = true;
+		}
+
+		/*
+		 * First, deal with the hole before the allocated space
+		 * that we found, if any.
+		 */
+		if (need_alloc || wasdelay) {
+			bma.eof = eof;
+			bma.conv = !!(flags & XFS_BMAPI_CONVERT);
+			bma.wasdel = wasdelay;
+			bma.offset = bno;
+			bma.flags = flags;
+
+			/*
+			 * There's a 32/64 bit type mismatch between the
+			 * allocation length request (which can be 64 bits in
+			 * length) and the bma length request, which is
+			 * xfs_extlen_t and therefore 32 bits. Hence we have to
+			 * check for 32-bit overflows and handle them here.
+			 */
+			if (len > (xfs_filblks_t)XFS_MAX_BMBT_EXTLEN)
+				bma.length = XFS_MAX_BMBT_EXTLEN;
+			else
+				bma.length = len;
+
+			ASSERT(len > 0);
+			ASSERT(bma.length > 0);
+			error = xfs_bmapi_allocate(&bma);
+			if (error)
+				goto error0;
+			if (bma.blkno == NULLFSBLOCK)
+				break;
+
+			/*
+			 * If this is a CoW allocation, record the data in
+			 * the refcount btree for orphan recovery.
+			 */
+			if (whichfork == XFS_COW_FORK)
+				xfs_refcount_alloc_cow_extent(tp, bma.blkno,
+						bma.length);
+		}
+
+		/* Deal with the allocated space we found.  */
+		xfs_bmapi_trim_map(mval, &bma.got, &bno, len, obno,
+							end, n, flags);
+
+		/* Execute unwritten extent conversion if necessary */
+		error = xfs_bmapi_convert_unwritten(&bma, mval, len, flags);
+		if (error == -EAGAIN)
+			continue;
+		if (error)
+			goto error0;
+
+		/* update the extent map to return */
+		xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);
+
+		/*
+		 * If we're done, stop now.  Stop when we've allocated
+		 * XFS_BMAP_MAX_NMAP extents no matter what.  Otherwise
+		 * the transaction may get too big.
+		 */
+		if (bno >= end || n >= *nmap || bma.nallocs >= *nmap)
+			break;
+
+		/* Else go on to the next record. */
+		bma.prev = bma.got;
+		if (!xfs_iext_next_extent(ifp, &bma.icur, &bma.got))
+			eof = true;
+	}
+	*nmap = n;
+
+	error = xfs_bmap_btree_to_extents(tp, ip, bma.cur, &bma.logflags,
+			whichfork);
+	if (error)
+		goto error0;
+
+	ASSERT(ifp->if_format != XFS_DINODE_FMT_BTREE ||
+	       ifp->if_nextents > XFS_IFORK_MAXEXT(ip, whichfork));
+	xfs_bmapi_finish(&bma, whichfork, 0);
+	xfs_bmap_validate_ret(orig_bno, orig_len, orig_flags, orig_mval,
+		orig_nmap, *nmap);
+	return 0;
+error0:
+	xfs_bmapi_finish(&bma, whichfork, error);
+	return error;
+}
+
+/*
+ * Convert an existing delalloc extent to real blocks based on file offset. This
+ * attempts to allocate the entire delalloc extent and may require multiple
+ * invocations to allocate the target offset if a large enough physical extent
+ * is not available.
+ */
+int
+xfs_bmapi_convert_delalloc(
+	struct xfs_inode	*ip,
+	int			whichfork,
+	xfs_off_t		offset,
+	struct iomap		*iomap,
+	unsigned int		*seq)
+{
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	struct xfs_bmalloca	bma = { NULL };
+	uint16_t		flags = 0;
+	struct xfs_trans	*tp;
+	int			error;
+
+	if (whichfork == XFS_COW_FORK)
+		flags |= IOMAP_F_SHARED;
+
+	/*
+	 * Space for the extent and indirect blocks was reserved when the
+	 * delalloc extent was created so there's no need to do so here.
+	 */
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0,
+				XFS_TRANS_RESERVE, &tp);
+	if (error)
+		return error;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, 0);
+
+	error = xfs_iext_count_may_overflow(ip, whichfork,
+			XFS_IEXT_ADD_NOSPLIT_CNT);
+	if (error == -EFBIG)
+		error = xfs_iext_count_upgrade(tp, ip,
+				XFS_IEXT_ADD_NOSPLIT_CNT);
+	if (error)
+		goto out_trans_cancel;
+
+	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &bma.icur, &bma.got) ||
+	    bma.got.br_startoff > offset_fsb) {
+		/*
+		 * No extent found in the range we are trying to convert.  This
+		 * should only happen for the COW fork, where another thread
+		 * might have moved the extent to the data fork in the meantime.
+		 */
+		WARN_ON_ONCE(whichfork != XFS_COW_FORK);
+		error = -EAGAIN;
+		goto out_trans_cancel;
+	}
+
+	/*
+	 * If we find a real extent here we raced with another thread converting
+	 * the extent.  Just return the real extent at this offset.
+	 */
+	if (!isnullstartblock(bma.got.br_startblock)) {
+		xfs_bmbt_to_iomap(ip, iomap, &bma.got, 0, flags,
+				xfs_iomap_inode_sequence(ip, flags));
+		*seq = READ_ONCE(ifp->if_seq);
+		goto out_trans_cancel;
+	}
+
+	bma.tp = tp;
+	bma.ip = ip;
+	bma.wasdel = true;
+	bma.offset = bma.got.br_startoff;
+	bma.length = max_t(xfs_filblks_t, bma.got.br_blockcount,
+			XFS_MAX_BMBT_EXTLEN);
+	bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);
+
+	/*
+	 * When we're converting the delalloc reservations backing dirty pages
+	 * in the page cache, we must be careful about how we create the new
+	 * extents:
+	 *
+	 * New CoW fork extents are created unwritten, turned into real extents
+	 * when we're about to write the data to disk, and mapped into the data
+	 * fork after the write finishes.  End of story.
+	 *
+	 * New data fork extents must be mapped in as unwritten and converted
+	 * to real extents after the write succeeds to avoid exposing stale
+	 * disk contents if we crash.
+	 */
+	bma.flags = XFS_BMAPI_PREALLOC;
+	if (whichfork == XFS_COW_FORK)
+		bma.flags |= XFS_BMAPI_COWFORK;
+
+	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
+		bma.prev.br_startoff = NULLFILEOFF;
+
+	error = xfs_bmapi_allocate(&bma);
+	if (error)
+		goto out_finish;
+
+	error = -ENOSPC;
+	if (WARN_ON_ONCE(bma.blkno == NULLFSBLOCK))
+		goto out_finish;
+	error = -EFSCORRUPTED;
+	if (WARN_ON_ONCE(!xfs_valid_startblock(ip, bma.got.br_startblock)))
+		goto out_finish;
+
+	XFS_STATS_ADD(mp, xs_xstrat_bytes, XFS_FSB_TO_B(mp, bma.length));
+	XFS_STATS_INC(mp, xs_xstrat_quick);
+
+	ASSERT(!isnullstartblock(bma.got.br_startblock));
+	xfs_bmbt_to_iomap(ip, iomap, &bma.got, 0, flags,
+				xfs_iomap_inode_sequence(ip, flags));
+	*seq = READ_ONCE(ifp->if_seq);
+
+	if (whichfork == XFS_COW_FORK)
+		xfs_refcount_alloc_cow_extent(tp, bma.blkno, bma.length);
+
+	error = xfs_bmap_btree_to_extents(tp, ip, bma.cur, &bma.logflags,
+			whichfork);
+	if (error)
+		goto out_finish;
+
+	xfs_bmapi_finish(&bma, whichfork, 0);
+	error = xfs_trans_commit(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+
+out_finish:
+	xfs_bmapi_finish(&bma, whichfork, error);
+out_trans_cancel:
+	xfs_trans_cancel(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+}
+
+int
+xfs_bmapi_remap(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		bno,
+	xfs_filblks_t		len,
+	xfs_fsblock_t		startblock,
+	uint32_t		flags)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp;
+	struct xfs_btree_cur	*cur = NULL;
+	struct xfs_bmbt_irec	got;
+	struct xfs_iext_cursor	icur;
+	int			whichfork = xfs_bmapi_whichfork(flags);
+	int			logflags = 0, error;
+
+	ifp = xfs_ifork_ptr(ip, whichfork);
+	ASSERT(len > 0);
+	ASSERT(len <= (xfs_filblks_t)XFS_MAX_BMBT_EXTLEN);
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC |
+			   XFS_BMAPI_NORMAP)));
+	ASSERT((flags & (XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC)) !=
+			(XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC));
+
+	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
+	    XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) {
+		return -EFSCORRUPTED;
+	}
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	if (xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
+		/* make sure we only reflink into a hole. */
+		ASSERT(got.br_startoff > bno);
+		ASSERT(got.br_startoff - bno >= len);
+	}
+
+	ip->i_nblocks += len;
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+
+	if (ifp->if_format == XFS_DINODE_FMT_BTREE) {
+		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
+		cur->bc_ino.flags = 0;
+	}
+
+	got.br_startoff = bno;
+	got.br_startblock = startblock;
+	got.br_blockcount = len;
+	if (flags & XFS_BMAPI_PREALLOC)
+		got.br_state = XFS_EXT_UNWRITTEN;
+	else
+		got.br_state = XFS_EXT_NORM;
+
+	error = xfs_bmap_add_extent_hole_real(tp, ip, whichfork, &icur,
+			&cur, &got, &logflags, flags);
+	if (error)
+		goto error0;
+
+	error = xfs_bmap_btree_to_extents(tp, ip, cur, &logflags, whichfork);
+
+error0:
+	if (ip->i_df.if_format != XFS_DINODE_FMT_EXTENTS)
+		logflags &= ~XFS_ILOG_DEXT;
+	else if (ip->i_df.if_format != XFS_DINODE_FMT_BTREE)
+		logflags &= ~XFS_ILOG_DBROOT;
+
+	if (logflags)
+		xfs_trans_log_inode(tp, ip, logflags);
+	if (cur)
+		xfs_btree_del_cursor(cur, error);
+	return error;
+}
+
+/*
+ * When a delalloc extent is split (e.g., due to a hole punch), the original
+ * indlen reservation must be shared across the two new extents that are left
+ * behind.
+ *
+ * Given the original reservation and the worst case indlen for the two new
+ * extents (as calculated by xfs_bmap_worst_indlen()), split the original
+ * reservation fairly across the two new extents. If necessary, steal available
+ * blocks from a deleted extent to make up a reservation deficiency (e.g., if
+ * ores == 1). The number of stolen blocks is returned. The availability and
+ * subsequent accounting of stolen blocks is the responsibility of the caller.
+ */
+static xfs_filblks_t
+xfs_bmap_split_indlen(
+	xfs_filblks_t			ores,		/* original res. */
+	xfs_filblks_t			*indlen1,	/* ext1 worst indlen */
+	xfs_filblks_t			*indlen2,	/* ext2 worst indlen */
+	xfs_filblks_t			avail)		/* stealable blocks */
+{
+	xfs_filblks_t			len1 = *indlen1;
+	xfs_filblks_t			len2 = *indlen2;
+	xfs_filblks_t			nres = len1 + len2; /* new total res. */
+	xfs_filblks_t			stolen = 0;
+	xfs_filblks_t			resfactor;
+
+	/*
+	 * Steal as many blocks as we can to try and satisfy the worst case
+	 * indlen for both new extents.
+	 */
+	if (ores < nres && avail)
+		stolen = XFS_FILBLKS_MIN(nres - ores, avail);
+	ores += stolen;
+
+	 /* nothing else to do if we've satisfied the new reservation */
+	if (ores >= nres)
+		return stolen;
+
+	/*
+	 * We can't meet the total required reservation for the two extents.
+	 * Calculate the percent of the overall shortage between both extents
+	 * and apply this percentage to each of the requested indlen values.
+	 * This distributes the shortage fairly and reduces the chances that one
+	 * of the two extents is left with nothing when extents are repeatedly
+	 * split.
+	 */
+	resfactor = (ores * 100);
+	do_div(resfactor, nres);
+	len1 *= resfactor;
+	do_div(len1, 100);
+	len2 *= resfactor;
+	do_div(len2, 100);
+	ASSERT(len1 + len2 <= ores);
+	ASSERT(len1 < *indlen1 && len2 < *indlen2);
+
+	/*
+	 * Hand out the remainder to each extent. If one of the two reservations
+	 * is zero, we want to make sure that one gets a block first. The loop
+	 * below starts with len1, so hand len2 a block right off the bat if it
+	 * is zero.
+	 */
+	ores -= (len1 + len2);
+	ASSERT((*indlen1 - len1) + (*indlen2 - len2) >= ores);
+	if (ores && !len2 && *indlen2) {
+		len2++;
+		ores--;
+	}
+	while (ores) {
+		if (len1 < *indlen1) {
+			len1++;
+			ores--;
+		}
+		if (!ores)
+			break;
+		if (len2 < *indlen2) {
+			len2++;
+			ores--;
+		}
+	}
+
+	*indlen1 = len1;
+	*indlen2 = len2;
+
+	return stolen;
+}
+
+int
+xfs_bmap_del_extent_delay(
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_iext_cursor	*icur,
+	struct xfs_bmbt_irec	*got,
+	struct xfs_bmbt_irec	*del)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_bmbt_irec	new;
+	int64_t			da_old, da_new, da_diff = 0;
+	xfs_fileoff_t		del_endoff, got_endoff;
+	xfs_filblks_t		got_indlen, new_indlen, stolen;
+	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
+	int			error = 0;
+	bool			isrt;
+
+	XFS_STATS_INC(mp, xs_del_exlist);
+
+	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
+	del_endoff = del->br_startoff + del->br_blockcount;
+	got_endoff = got->br_startoff + got->br_blockcount;
+	da_old = startblockval(got->br_startblock);
+	da_new = 0;
+
+	ASSERT(del->br_blockcount > 0);
+	ASSERT(got->br_startoff <= del->br_startoff);
+	ASSERT(got_endoff >= del_endoff);
+
+	if (isrt) {
+		uint64_t rtexts = XFS_FSB_TO_B(mp, del->br_blockcount);
+
+		do_div(rtexts, mp->m_sb.sb_rextsize);
+		xfs_mod_frextents(mp, rtexts);
+	}
+
+	/*
+	 * Update the inode delalloc counter now and wait to update the
+	 * sb counters as we might have to borrow some blocks for the
+	 * indirect block accounting.
+	 */
+	ASSERT(!isrt);
+	error = xfs_quota_unreserve_blkres(ip, del->br_blockcount);
+	if (error)
+		return error;
+	ip->i_delayed_blks -= del->br_blockcount;
+
+	if (got->br_startoff == del->br_startoff)
+		state |= BMAP_LEFT_FILLING;
+	if (got_endoff == del_endoff)
+		state |= BMAP_RIGHT_FILLING;
+
+	switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
+		/*
+		 * Matches the whole extent.  Delete the entry.
+		 */
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		break;
+	case BMAP_LEFT_FILLING:
+		/*
+		 * Deleting the first part of the extent.
+		 */
+		got->br_startoff = del_endoff;
+		got->br_blockcount -= del->br_blockcount;
+		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
+				got->br_blockcount), da_old);
+		got->br_startblock = nullstartblock((int)da_new);
+		xfs_iext_update_extent(ip, state, icur, got);
+		break;
+	case BMAP_RIGHT_FILLING:
+		/*
+		 * Deleting the last part of the extent.
+		 */
+		got->br_blockcount = got->br_blockcount - del->br_blockcount;
+		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
+				got->br_blockcount), da_old);
+		got->br_startblock = nullstartblock((int)da_new);
+		xfs_iext_update_extent(ip, state, icur, got);
+		break;
+	case 0:
+		/*
+		 * Deleting the middle of the extent.
+		 *
+		 * Distribute the original indlen reservation across the two new
+		 * extents.  Steal blocks from the deleted extent if necessary.
+		 * Stealing blocks simply fudges the fdblocks accounting below.
+		 * Warn if either of the new indlen reservations is zero as this
+		 * can lead to delalloc problems.
+		 */
+		got->br_blockcount = del->br_startoff - got->br_startoff;
+		got_indlen = xfs_bmap_worst_indlen(ip, got->br_blockcount);
+
+		new.br_blockcount = got_endoff - del_endoff;
+		new_indlen = xfs_bmap_worst_indlen(ip, new.br_blockcount);
+
+		WARN_ON_ONCE(!got_indlen || !new_indlen);
+		stolen = xfs_bmap_split_indlen(da_old, &got_indlen, &new_indlen,
+						       del->br_blockcount);
+
+		got->br_startblock = nullstartblock((int)got_indlen);
+
+		new.br_startoff = del_endoff;
+		new.br_state = got->br_state;
+		new.br_startblock = nullstartblock((int)new_indlen);
+
+		xfs_iext_update_extent(ip, state, icur, got);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, &new, state);
+
+		da_new = got_indlen + new_indlen - stolen;
+		del->br_blockcount -= stolen;
+		break;
+	}
+
+	ASSERT(da_old >= da_new);
+	da_diff = da_old - da_new;
+	if (!isrt)
+		da_diff += del->br_blockcount;
+	if (da_diff) {
+		xfs_mod_fdblocks(mp, da_diff, false);
+		xfs_mod_delalloc(mp, -da_diff);
+	}
+	return error;
+}
+
+void
+xfs_bmap_del_extent_cow(
+	struct xfs_inode	*ip,
+	struct xfs_iext_cursor	*icur,
+	struct xfs_bmbt_irec	*got,
+	struct xfs_bmbt_irec	*del)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
+	struct xfs_bmbt_irec	new;
+	xfs_fileoff_t		del_endoff, got_endoff;
+	uint32_t		state = BMAP_COWFORK;
+
+	XFS_STATS_INC(mp, xs_del_exlist);
+
+	del_endoff = del->br_startoff + del->br_blockcount;
+	got_endoff = got->br_startoff + got->br_blockcount;
+
+	ASSERT(del->br_blockcount > 0);
+	ASSERT(got->br_startoff <= del->br_startoff);
+	ASSERT(got_endoff >= del_endoff);
+	ASSERT(!isnullstartblock(got->br_startblock));
+
+	if (got->br_startoff == del->br_startoff)
+		state |= BMAP_LEFT_FILLING;
+	if (got_endoff == del_endoff)
+		state |= BMAP_RIGHT_FILLING;
+
+	switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
+		/*
+		 * Matches the whole extent.  Delete the entry.
+		 */
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		break;
+	case BMAP_LEFT_FILLING:
+		/*
+		 * Deleting the first part of the extent.
+		 */
+		got->br_startoff = del_endoff;
+		got->br_blockcount -= del->br_blockcount;
+		got->br_startblock = del->br_startblock + del->br_blockcount;
+		xfs_iext_update_extent(ip, state, icur, got);
+		break;
+	case BMAP_RIGHT_FILLING:
+		/*
+		 * Deleting the last part of the extent.
+		 */
+		got->br_blockcount -= del->br_blockcount;
+		xfs_iext_update_extent(ip, state, icur, got);
+		break;
+	case 0:
+		/*
+		 * Deleting the middle of the extent.
+		 */
+		got->br_blockcount = del->br_startoff - got->br_startoff;
+
+		new.br_startoff = del_endoff;
+		new.br_blockcount = got_endoff - del_endoff;
+		new.br_state = got->br_state;
+		new.br_startblock = del->br_startblock + del->br_blockcount;
+
+		xfs_iext_update_extent(ip, state, icur, got);
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, &new, state);
+		break;
+	}
+	ip->i_delayed_blks -= del->br_blockcount;
+}
+
+/*
+ * Called by xfs_bmapi to update file extent records and the btree
+ * after removing space.
+ */
+STATIC int				/* error */
+xfs_bmap_del_extent_real(
+	xfs_inode_t		*ip,	/* incore inode pointer */
+	xfs_trans_t		*tp,	/* current transaction pointer */
+	struct xfs_iext_cursor	*icur,
+	struct xfs_btree_cur	*cur,	/* if null, not a btree */
+	xfs_bmbt_irec_t		*del,	/* data to remove from extents */
+	int			*logflagsp, /* inode logging flags */
+	int			whichfork, /* data or attr fork */
+	uint32_t		bflags)	/* bmapi flags */
+{
+	xfs_fsblock_t		del_endblock=0;	/* first block past del */
+	xfs_fileoff_t		del_endoff;	/* first offset past del */
+	int			do_fx;	/* free extent at end of routine */
+	int			error;	/* error return value */
+	int			flags = 0;/* inode logging flags */
+	struct xfs_bmbt_irec	got;	/* current extent entry */
+	xfs_fileoff_t		got_endoff;	/* first offset past got */
+	int			i;	/* temp state */
+	struct xfs_ifork	*ifp;	/* inode fork pointer */
+	xfs_mount_t		*mp;	/* mount structure */
+	xfs_filblks_t		nblks;	/* quota/sb block count */
+	xfs_bmbt_irec_t		new;	/* new record to be inserted */
+	/* REFERENCED */
+	uint			qfield;	/* quota field to update */
+	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
+	struct xfs_bmbt_irec	old;
+
+	mp = ip->i_mount;
+	XFS_STATS_INC(mp, xs_del_exlist);
+
+	ifp = xfs_ifork_ptr(ip, whichfork);
+	ASSERT(del->br_blockcount > 0);
+	xfs_iext_get_extent(ifp, icur, &got);
+	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);
+	ASSERT(!isnullstartblock(got.br_startblock));
+	qfield = 0;
+	error = 0;
+
+	/*
+	 * If it's the case where the directory code is running with no block
+	 * reservation, and the deleted block is in the middle of its extent,
+	 * and the resulting insert of an extent would cause transformation to
+	 * btree format, then reject it.  The calling code will then swap blocks
+	 * around instead.  We have to do this now, rather than waiting for the
+	 * conversion to btree format, since the transaction will be dirty then.
+	 */
+	if (tp->t_blk_res == 0 &&
+	    ifp->if_format == XFS_DINODE_FMT_EXTENTS &&
+	    ifp->if_nextents >= XFS_IFORK_MAXEXT(ip, whichfork) &&
+	    del->br_startoff > got.br_startoff && del_endoff < got_endoff)
+		return -ENOSPC;
+
+	flags = XFS_ILOG_CORE;
+	if (whichfork == XFS_DATA_FORK && XFS_IS_REALTIME_INODE(ip)) {
+		xfs_filblks_t	len;
+		xfs_extlen_t	mod;
+
+		len = div_u64_rem(del->br_blockcount, mp->m_sb.sb_rextsize,
+				  &mod);
+		ASSERT(mod == 0);
+
+		if (!(bflags & XFS_BMAPI_REMAP)) {
+			xfs_fsblock_t	bno;
+
+			bno = div_u64_rem(del->br_startblock,
+					mp->m_sb.sb_rextsize, &mod);
+			ASSERT(mod == 0);
+
+			error = xfs_rtfree_extent(tp, bno, (xfs_extlen_t)len);
+			if (error)
+				goto done;
+		}
+
+		do_fx = 0;
+		nblks = len * mp->m_sb.sb_rextsize;
+		qfield = XFS_TRANS_DQ_RTBCOUNT;
+	} else {
+		do_fx = 1;
+		nblks = del->br_blockcount;
+		qfield = XFS_TRANS_DQ_BCOUNT;
+	}
+
+	del_endblock = del->br_startblock + del->br_blockcount;
+	if (cur) {
+		error = xfs_bmbt_lookup_eq(cur, &got, &i);
+		if (error)
+			goto done;
+		if (XFS_IS_CORRUPT(mp, i != 1)) {
+			error = -EFSCORRUPTED;
+			goto done;
+		}
+	}
+
+	if (got.br_startoff == del->br_startoff)
+		state |= BMAP_LEFT_FILLING;
+	if (got_endoff == del_endoff)
+		state |= BMAP_RIGHT_FILLING;
+
+	switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
+	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
+		/*
+		 * Matches the whole extent.  Delete the entry.
+		 */
+		xfs_iext_remove(ip, icur, state);
+		xfs_iext_prev(ifp, icur);
+		ifp->if_nextents--;
+
+		flags |= XFS_ILOG_CORE;
+		if (!cur) {
+			flags |= xfs_ilog_fext(whichfork);
+			break;
+		}
+		if ((error = xfs_btree_delete(cur, &i)))
+			goto done;
+		if (XFS_IS_CORRUPT(mp, i != 1)) {
+			error = -EFSCORRUPTED;
+			goto done;
+		}
+		break;
+	case BMAP_LEFT_FILLING:
+		/*
+		 * Deleting the first part of the extent.
+		 */
+		got.br_startoff = del_endoff;
+		got.br_startblock = del_endblock;
+		got.br_blockcount -= del->br_blockcount;
+		xfs_iext_update_extent(ip, state, icur, &got);
+		if (!cur) {
+			flags |= xfs_ilog_fext(whichfork);
+			break;
+		}
+		error = xfs_bmbt_update(cur, &got);
+		if (error)
+			goto done;
+		break;
+	case BMAP_RIGHT_FILLING:
+		/*
+		 * Deleting the last part of the extent.
+		 */
+		got.br_blockcount -= del->br_blockcount;
+		xfs_iext_update_extent(ip, state, icur, &got);
+		if (!cur) {
+			flags |= xfs_ilog_fext(whichfork);
+			break;
+		}
+		error = xfs_bmbt_update(cur, &got);
+		if (error)
+			goto done;
+		break;
+	case 0:
+		/*
+		 * Deleting the middle of the extent.
+		 */
+
+		old = got;
+
+		got.br_blockcount = del->br_startoff - got.br_startoff;
+		xfs_iext_update_extent(ip, state, icur, &got);
+
+		new.br_startoff = del_endoff;
+		new.br_blockcount = got_endoff - del_endoff;
+		new.br_state = got.br_state;
+		new.br_startblock = del_endblock;
+
+		flags |= XFS_ILOG_CORE;
+		if (cur) {
+			error = xfs_bmbt_update(cur, &got);
+			if (error)
+				goto done;
+			error = xfs_btree_increment(cur, 0, &i);
+			if (error)
+				goto done;
+			cur->bc_rec.b = new;
+			error = xfs_btree_insert(cur, &i);
+			if (error && error != -ENOSPC)
+				goto done;
+			/*
+			 * If get no-space back from btree insert, it tried a
+			 * split, and we have a zero block reservation.  Fix up
+			 * our state and return the error.
+			 */
+			if (error == -ENOSPC) {
+				/*
+				 * Reset the cursor, don't trust it after any
+				 * insert operation.
+				 */
+				error = xfs_bmbt_lookup_eq(cur, &got, &i);
+				if (error)
+					goto done;
+				if (XFS_IS_CORRUPT(mp, i != 1)) {
+					error = -EFSCORRUPTED;
+					goto done;
+				}
+				/*
+				 * Update the btree record back
+				 * to the original value.
+				 */
+				error = xfs_bmbt_update(cur, &old);
+				if (error)
+					goto done;
+				/*
+				 * Reset the extent record back
+				 * to the original value.
+				 */
+				xfs_iext_update_extent(ip, state, icur, &old);
+				flags = 0;
+				error = -ENOSPC;
+				goto done;
+			}
+			if (XFS_IS_CORRUPT(mp, i != 1)) {
+				error = -EFSCORRUPTED;
+				goto done;
+			}
+		} else
+			flags |= xfs_ilog_fext(whichfork);
+
+		ifp->if_nextents++;
+		xfs_iext_next(ifp, icur);
+		xfs_iext_insert(ip, icur, &new, state);
+		break;
+	}
+
+	/* remove reverse mapping */
+	xfs_rmap_unmap_extent(tp, ip, whichfork, del);
+
+	/*
+	 * If we need to, add to list of extents to delete.
+	 */
+	if (do_fx && !(bflags & XFS_BMAPI_REMAP)) {
+		if (xfs_is_reflink_inode(ip) && whichfork == XFS_DATA_FORK) {
+			xfs_refcount_decrease_extent(tp, del);
+		} else {
+			error = __xfs_free_extent_later(tp, del->br_startblock,
+					del->br_blockcount, NULL,
+					XFS_AG_RESV_NONE,
+					((bflags & XFS_BMAPI_NODISCARD) ||
+					del->br_state == XFS_EXT_UNWRITTEN));
+			if (error)
+				goto done;
+		}
+	}
+
+	/*
+	 * Adjust inode # blocks in the file.
+	 */
+	if (nblks)
+		ip->i_nblocks -= nblks;
+	/*
+	 * Adjust quota data.
+	 */
+	if (qfield && !(bflags & XFS_BMAPI_REMAP))
+		xfs_trans_mod_dquot_byino(tp, ip, qfield, (long)-nblks);
+
+done:
+	*logflagsp = flags;
+	return error;
+}
+
+/*
+ * Unmap (remove) blocks from a file.
+ * If nexts is nonzero then the number of extents to remove is limited to
+ * that value.  If not all extents in the block range can be removed then
+ * *done is set.
+ */
+int						/* error */
+__xfs_bunmapi(
+	struct xfs_trans	*tp,		/* transaction pointer */
+	struct xfs_inode	*ip,		/* incore inode */
+	xfs_fileoff_t		start,		/* first file offset deleted */
+	xfs_filblks_t		*rlen,		/* i/o: amount remaining */
+	uint32_t		flags,		/* misc flags */
+	xfs_extnum_t		nexts)		/* number of extents max */
+{
+	struct xfs_btree_cur	*cur;		/* bmap btree cursor */
+	struct xfs_bmbt_irec	del;		/* extent being deleted */
+	int			error;		/* error return value */
+	xfs_extnum_t		extno;		/* extent number in list */
+	struct xfs_bmbt_irec	got;		/* current extent record */
+	struct xfs_ifork	*ifp;		/* inode fork pointer */
+	int			isrt;		/* freeing in rt area */
+	int			logflags;	/* transaction logging flags */
+	xfs_extlen_t		mod;		/* rt extent offset */
+	struct xfs_mount	*mp = ip->i_mount;
+	int			tmp_logflags;	/* partial logging flags */
+	int			wasdel;		/* was a delayed alloc extent */
+	int			whichfork;	/* data or attribute fork */
+	xfs_fsblock_t		sum;
+	xfs_filblks_t		len = *rlen;	/* length to unmap in file */
+	xfs_fileoff_t		end;
+	struct xfs_iext_cursor	icur;
+	bool			done = false;
+
+	trace_xfs_bunmap(ip, start, len, flags, _RET_IP_);
+
+	whichfork = xfs_bmapi_whichfork(flags);
+	ASSERT(whichfork != XFS_COW_FORK);
+	ifp = xfs_ifork_ptr(ip, whichfork);
+	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)))
+		return -EFSCORRUPTED;
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	ASSERT(len > 0);
+	ASSERT(nexts >= 0);
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	if (xfs_iext_count(ifp) == 0) {
+		*rlen = 0;
+		return 0;
+	}
+	XFS_STATS_INC(mp, xs_blk_unmap);
+	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
+	end = start + len;
+
+	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &icur, &got)) {
+		*rlen = 0;
+		return 0;
+	}
+	end--;
+
+	logflags = 0;
+	if (ifp->if_format == XFS_DINODE_FMT_BTREE) {
+		ASSERT(ifp->if_format == XFS_DINODE_FMT_BTREE);
+		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
+		cur->bc_ino.flags = 0;
+	} else
+		cur = NULL;
+
+	if (isrt) {
+		/*
+		 * Synchronize by locking the bitmap inode.
+		 */
+		xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL|XFS_ILOCK_RTBITMAP);
+		xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
+		xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL|XFS_ILOCK_RTSUM);
+		xfs_trans_ijoin(tp, mp->m_rsumip, XFS_ILOCK_EXCL);
+	}
+
+	extno = 0;
+	while (end != (xfs_fileoff_t)-1 && end >= start &&
+	       (nexts == 0 || extno < nexts)) {
+		/*
+		 * Is the found extent after a hole in which end lives?
+		 * Just back up to the previous extent, if so.
+		 */
+		if (got.br_startoff > end &&
+		    !xfs_iext_prev_extent(ifp, &icur, &got)) {
+			done = true;
+			break;
+		}
+		/*
+		 * Is the last block of this extent before the range
+		 * we're supposed to delete?  If so, we're done.
+		 */
+		end = XFS_FILEOFF_MIN(end,
+			got.br_startoff + got.br_blockcount - 1);
+		if (end < start)
+			break;
+		/*
+		 * Then deal with the (possibly delayed) allocated space
+		 * we found.
+		 */
+		del = got;
+		wasdel = isnullstartblock(del.br_startblock);
+
+		if (got.br_startoff < start) {
+			del.br_startoff = start;
+			del.br_blockcount -= start - got.br_startoff;
+			if (!wasdel)
+				del.br_startblock += start - got.br_startoff;
+		}
+		if (del.br_startoff + del.br_blockcount > end + 1)
+			del.br_blockcount = end + 1 - del.br_startoff;
+
+		if (!isrt)
+			goto delete;
+
+		sum = del.br_startblock + del.br_blockcount;
+		div_u64_rem(sum, mp->m_sb.sb_rextsize, &mod);
+		if (mod) {
+			/*
+			 * Realtime extent not lined up at the end.
+			 * The extent could have been split into written
+			 * and unwritten pieces, or we could just be
+			 * unmapping part of it.  But we can't really
+			 * get rid of part of a realtime extent.
+			 */
+			if (del.br_state == XFS_EXT_UNWRITTEN) {
+				/*
+				 * This piece is unwritten, or we're not
+				 * using unwritten extents.  Skip over it.
+				 */
+				ASSERT(end >= mod);
+				end -= mod > del.br_blockcount ?
+					del.br_blockcount : mod;
+				if (end < got.br_startoff &&
+				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
+					done = true;
+					break;
+				}
+				continue;
+			}
+			/*
+			 * It's written, turn it unwritten.
+			 * This is better than zeroing it.
+			 */
+			ASSERT(del.br_state == XFS_EXT_NORM);
+			ASSERT(tp->t_blk_res > 0);
+			/*
+			 * If this spans a realtime extent boundary,
+			 * chop it back to the start of the one we end at.
+			 */
+			if (del.br_blockcount > mod) {
+				del.br_startoff += del.br_blockcount - mod;
+				del.br_startblock += del.br_blockcount - mod;
+				del.br_blockcount = mod;
+			}
+			del.br_state = XFS_EXT_UNWRITTEN;
+			error = xfs_bmap_add_extent_unwritten_real(tp, ip,
+					whichfork, &icur, &cur, &del,
+					&logflags);
+			if (error)
+				goto error0;
+			goto nodelete;
+		}
+		div_u64_rem(del.br_startblock, mp->m_sb.sb_rextsize, &mod);
+		if (mod) {
+			xfs_extlen_t off = mp->m_sb.sb_rextsize - mod;
+
+			/*
+			 * Realtime extent is lined up at the end but not
+			 * at the front.  We'll get rid of full extents if
+			 * we can.
+			 */
+			if (del.br_blockcount > off) {
+				del.br_blockcount -= off;
+				del.br_startoff += off;
+				del.br_startblock += off;
+			} else if (del.br_startoff == start &&
+				   (del.br_state == XFS_EXT_UNWRITTEN ||
+				    tp->t_blk_res == 0)) {
+				/*
+				 * Can't make it unwritten.  There isn't
+				 * a full extent here so just skip it.
+				 */
+				ASSERT(end >= del.br_blockcount);
+				end -= del.br_blockcount;
+				if (got.br_startoff > end &&
+				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
+					done = true;
+					break;
+				}
+				continue;
+			} else if (del.br_state == XFS_EXT_UNWRITTEN) {
+				struct xfs_bmbt_irec	prev;
+				xfs_fileoff_t		unwrite_start;
+
+				/*
+				 * This one is already unwritten.
+				 * It must have a written left neighbor.
+				 * Unwrite the killed part of that one and
+				 * try again.
+				 */
+				if (!xfs_iext_prev_extent(ifp, &icur, &prev))
+					ASSERT(0);
+				ASSERT(prev.br_state == XFS_EXT_NORM);
+				ASSERT(!isnullstartblock(prev.br_startblock));
+				ASSERT(del.br_startblock ==
+				       prev.br_startblock + prev.br_blockcount);
+				unwrite_start = max3(start,
+						     del.br_startoff - mod,
+						     prev.br_startoff);
+				mod = unwrite_start - prev.br_startoff;
+				prev.br_startoff = unwrite_start;
+				prev.br_startblock += mod;
+				prev.br_blockcount -= mod;
+				prev.br_state = XFS_EXT_UNWRITTEN;
+				error = xfs_bmap_add_extent_unwritten_real(tp,
+						ip, whichfork, &icur, &cur,
+						&prev, &logflags);
+				if (error)
+					goto error0;
+				goto nodelete;
+			} else {
+				ASSERT(del.br_state == XFS_EXT_NORM);
+				del.br_state = XFS_EXT_UNWRITTEN;
+				error = xfs_bmap_add_extent_unwritten_real(tp,
+						ip, whichfork, &icur, &cur,
+						&del, &logflags);
+				if (error)
+					goto error0;
+				goto nodelete;
+			}
+		}
+
+delete:
+		if (wasdel) {
+			error = xfs_bmap_del_extent_delay(ip, whichfork, &icur,
+					&got, &del);
+		} else {
+			error = xfs_bmap_del_extent_real(ip, tp, &icur, cur,
+					&del, &tmp_logflags, whichfork,
+					flags);
+			logflags |= tmp_logflags;
+		}
+
+		if (error)
+			goto error0;
+
+		end = del.br_startoff - 1;
+nodelete:
+		/*
+		 * If not done go on to the next (previous) record.
+		 */
+		if (end != (xfs_fileoff_t)-1 && end >= start) {
+			if (!xfs_iext_get_extent(ifp, &icur, &got) ||
+			    (got.br_startoff > end &&
+			     !xfs_iext_prev_extent(ifp, &icur, &got))) {
+				done = true;
+				break;
+			}
+			extno++;
+		}
+	}
+	if (done || end == (xfs_fileoff_t)-1 || end < start)
+		*rlen = 0;
+	else
+		*rlen = end - start + 1;
+
+	/*
+	 * Convert to a btree if necessary.
+	 */
+	if (xfs_bmap_needs_btree(ip, whichfork)) {
+		ASSERT(cur == NULL);
+		error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
+				&tmp_logflags, whichfork);
+		logflags |= tmp_logflags;
+	} else {
+		error = xfs_bmap_btree_to_extents(tp, ip, cur, &logflags,
+			whichfork);
+	}
+
+error0:
+	/*
+	 * Log everything.  Do this after conversion, there's no point in
+	 * logging the extent records if we've converted to btree format.
+	 */
+	if ((logflags & xfs_ilog_fext(whichfork)) &&
+	    ifp->if_format != XFS_DINODE_FMT_EXTENTS)
+		logflags &= ~xfs_ilog_fext(whichfork);
+	else if ((logflags & xfs_ilog_fbroot(whichfork)) &&
+		 ifp->if_format != XFS_DINODE_FMT_BTREE)
+		logflags &= ~xfs_ilog_fbroot(whichfork);
+	/*
+	 * Log inode even in the error case, if the transaction
+	 * is dirty we'll need to shut down the filesystem.
+	 */
+	if (logflags)
+		xfs_trans_log_inode(tp, ip, logflags);
+	if (cur) {
+		if (!error)
+			cur->bc_ino.allocated = 0;
+		xfs_btree_del_cursor(cur, error);
+	}
+	return error;
+}
+
+/* Unmap a range of a file. */
+int
+xfs_bunmapi(
+	xfs_trans_t		*tp,
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		bno,
+	xfs_filblks_t		len,
+	uint32_t		flags,
+	xfs_extnum_t		nexts,
+	int			*done)
+{
+	int			error;
+
+	error = __xfs_bunmapi(tp, ip, bno, &len, flags, nexts);
+	*done = (len == 0);
+	return error;
+}
+
+/*
+ * Determine whether an extent shift can be accomplished by a merge with the
+ * extent that precedes the target hole of the shift.
+ */
+STATIC bool
+xfs_bmse_can_merge(
+	struct xfs_bmbt_irec	*left,	/* preceding extent */
+	struct xfs_bmbt_irec	*got,	/* current extent to shift */
+	xfs_fileoff_t		shift)	/* shift fsb */
+{
+	xfs_fileoff_t		startoff;
+
+	startoff = got->br_startoff - shift;
+
+	/*
+	 * The extent, once shifted, must be adjacent in-file and on-disk with
+	 * the preceding extent.
+	 */
+	if ((left->br_startoff + left->br_blockcount != startoff) ||
+	    (left->br_startblock + left->br_blockcount != got->br_startblock) ||
+	    (left->br_state != got->br_state) ||
+	    (left->br_blockcount + got->br_blockcount > XFS_MAX_BMBT_EXTLEN))
+		return false;
+
+	return true;
+}
+
+/*
+ * A bmap extent shift adjusts the file offset of an extent to fill a preceding
+ * hole in the file. If an extent shift would result in the extent being fully
+ * adjacent to the extent that currently precedes the hole, we can merge with
+ * the preceding extent rather than do the shift.
+ *
+ * This function assumes the caller has verified a shift-by-merge is possible
+ * with the provided extents via xfs_bmse_can_merge().
+ */
+STATIC int
+xfs_bmse_merge(
+	struct xfs_trans		*tp,
+	struct xfs_inode		*ip,
+	int				whichfork,
+	xfs_fileoff_t			shift,		/* shift fsb */
+	struct xfs_iext_cursor		*icur,
+	struct xfs_bmbt_irec		*got,		/* extent to shift */
+	struct xfs_bmbt_irec		*left,		/* preceding extent */
+	struct xfs_btree_cur		*cur,
+	int				*logflags)	/* output */
+{
+	struct xfs_ifork		*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_bmbt_irec		new;
+	xfs_filblks_t			blockcount;
+	int				error, i;
+	struct xfs_mount		*mp = ip->i_mount;
+
+	blockcount = left->br_blockcount + got->br_blockcount;
+
+	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	ASSERT(xfs_bmse_can_merge(left, got, shift));
+
+	new = *left;
+	new.br_blockcount = blockcount;
+
+	/*
+	 * Update the on-disk extent count, the btree if necessary and log the
+	 * inode.
+	 */
+	ifp->if_nextents--;
+	*logflags |= XFS_ILOG_CORE;
+	if (!cur) {
+		*logflags |= XFS_ILOG_DEXT;
+		goto done;
+	}
+
+	/* lookup and remove the extent to merge */
+	error = xfs_bmbt_lookup_eq(cur, got, &i);
+	if (error)
+		return error;
+	if (XFS_IS_CORRUPT(mp, i != 1))
+		return -EFSCORRUPTED;
+
+	error = xfs_btree_delete(cur, &i);
+	if (error)
+		return error;
+	if (XFS_IS_CORRUPT(mp, i != 1))
+		return -EFSCORRUPTED;
+
+	/* lookup and update size of the previous extent */
+	error = xfs_bmbt_lookup_eq(cur, left, &i);
+	if (error)
+		return error;
+	if (XFS_IS_CORRUPT(mp, i != 1))
+		return -EFSCORRUPTED;
+
+	error = xfs_bmbt_update(cur, &new);
+	if (error)
+		return error;
+
+	/* change to extent format if required after extent removal */
+	error = xfs_bmap_btree_to_extents(tp, ip, cur, logflags, whichfork);
+	if (error)
+		return error;
+
+done:
+	xfs_iext_remove(ip, icur, 0);
+	xfs_iext_prev(ifp, icur);
+	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
+			&new);
+
+	/* update reverse mapping. rmap functions merge the rmaps for us */
+	xfs_rmap_unmap_extent(tp, ip, whichfork, got);
+	memcpy(&new, got, sizeof(new));
+	new.br_startoff = left->br_startoff + left->br_blockcount;
+	xfs_rmap_map_extent(tp, ip, whichfork, &new);
+	return 0;
+}
+
+static int
+xfs_bmap_shift_update_extent(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_iext_cursor	*icur,
+	struct xfs_bmbt_irec	*got,
+	struct xfs_btree_cur	*cur,
+	int			*logflags,
+	xfs_fileoff_t		startoff)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_bmbt_irec	prev = *got;
+	int			error, i;
+
+	*logflags |= XFS_ILOG_CORE;
+
+	got->br_startoff = startoff;
+
+	if (cur) {
+		error = xfs_bmbt_lookup_eq(cur, &prev, &i);
+		if (error)
+			return error;
+		if (XFS_IS_CORRUPT(mp, i != 1))
+			return -EFSCORRUPTED;
+
+		error = xfs_bmbt_update(cur, got);
+		if (error)
+			return error;
+	} else {
+		*logflags |= XFS_ILOG_DEXT;
+	}
+
+	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
+			got);
+
+	/* update reverse mapping */
+	xfs_rmap_unmap_extent(tp, ip, whichfork, &prev);
+	xfs_rmap_map_extent(tp, ip, whichfork, got);
+	return 0;
+}
+
+int
+xfs_bmap_collapse_extents(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		*next_fsb,
+	xfs_fileoff_t		offset_shift_fsb,
+	bool			*done)
+{
+	int			whichfork = XFS_DATA_FORK;
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_btree_cur	*cur = NULL;
+	struct xfs_bmbt_irec	got, prev;
+	struct xfs_iext_cursor	icur;
+	xfs_fileoff_t		new_startoff;
+	int			error = 0;
+	int			logflags = 0;
+
+	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
+	    XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) {
+		return -EFSCORRUPTED;
+	}
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL));
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	if (ifp->if_format == XFS_DINODE_FMT_BTREE) {
+		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
+		cur->bc_ino.flags = 0;
+	}
+
+	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
+		*done = true;
+		goto del_cursor;
+	}
+	if (XFS_IS_CORRUPT(mp, isnullstartblock(got.br_startblock))) {
+		error = -EFSCORRUPTED;
+		goto del_cursor;
+	}
+
+	new_startoff = got.br_startoff - offset_shift_fsb;
+	if (xfs_iext_peek_prev_extent(ifp, &icur, &prev)) {
+		if (new_startoff < prev.br_startoff + prev.br_blockcount) {
+			error = -EINVAL;
+			goto del_cursor;
+		}
+
+		if (xfs_bmse_can_merge(&prev, &got, offset_shift_fsb)) {
+			error = xfs_bmse_merge(tp, ip, whichfork,
+					offset_shift_fsb, &icur, &got, &prev,
+					cur, &logflags);
+			if (error)
+				goto del_cursor;
+			goto done;
+		}
+	} else {
+		if (got.br_startoff < offset_shift_fsb) {
+			error = -EINVAL;
+			goto del_cursor;
+		}
+	}
+
+	error = xfs_bmap_shift_update_extent(tp, ip, whichfork, &icur, &got,
+			cur, &logflags, new_startoff);
+	if (error)
+		goto del_cursor;
+
+done:
+	if (!xfs_iext_next_extent(ifp, &icur, &got)) {
+		*done = true;
+		goto del_cursor;
+	}
+
+	*next_fsb = got.br_startoff;
+del_cursor:
+	if (cur)
+		xfs_btree_del_cursor(cur, error);
+	if (logflags)
+		xfs_trans_log_inode(tp, ip, logflags);
+	return error;
+}
+
+/* Make sure we won't be right-shifting an extent past the maximum bound. */
+int
+xfs_bmap_can_insert_extents(
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		off,
+	xfs_fileoff_t		shift)
+{
+	struct xfs_bmbt_irec	got;
+	int			is_empty;
+	int			error = 0;
+
+	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+
+	if (xfs_is_shutdown(ip->i_mount))
+		return -EIO;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	error = xfs_bmap_last_extent(NULL, ip, XFS_DATA_FORK, &got, &is_empty);
+	if (!error && !is_empty && got.br_startoff >= off &&
+	    ((got.br_startoff + shift) & BMBT_STARTOFF_MASK) < got.br_startoff)
+		error = -EINVAL;
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+	return error;
+}
+
+int
+xfs_bmap_insert_extents(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		*next_fsb,
+	xfs_fileoff_t		offset_shift_fsb,
+	bool			*done,
+	xfs_fileoff_t		stop_fsb)
+{
+	int			whichfork = XFS_DATA_FORK;
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_btree_cur	*cur = NULL;
+	struct xfs_bmbt_irec	got, next;
+	struct xfs_iext_cursor	icur;
+	xfs_fileoff_t		new_startoff;
+	int			error = 0;
+	int			logflags = 0;
+
+	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
+	    XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) {
+		return -EFSCORRUPTED;
+	}
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL));
+
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	if (ifp->if_format == XFS_DINODE_FMT_BTREE) {
+		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
+		cur->bc_ino.flags = 0;
+	}
+
+	if (*next_fsb == NULLFSBLOCK) {
+		xfs_iext_last(ifp, &icur);
+		if (!xfs_iext_get_extent(ifp, &icur, &got) ||
+		    stop_fsb > got.br_startoff) {
+			*done = true;
+			goto del_cursor;
+		}
+	} else {
+		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
+			*done = true;
+			goto del_cursor;
+		}
+	}
+	if (XFS_IS_CORRUPT(mp, isnullstartblock(got.br_startblock))) {
+		error = -EFSCORRUPTED;
+		goto del_cursor;
+	}
+
+	if (XFS_IS_CORRUPT(mp, stop_fsb > got.br_startoff)) {
+		error = -EFSCORRUPTED;
+		goto del_cursor;
+	}
+
+	new_startoff = got.br_startoff + offset_shift_fsb;
+	if (xfs_iext_peek_next_extent(ifp, &icur, &next)) {
+		if (new_startoff + got.br_blockcount > next.br_startoff) {
+			error = -EINVAL;
+			goto del_cursor;
+		}
+
+		/*
+		 * Unlike a left shift (which involves a hole punch), a right
+		 * shift does not modify extent neighbors in any way.  We should
+		 * never find mergeable extents in this scenario.  Check anyways
+		 * and warn if we encounter two extents that could be one.
+		 */
+		if (xfs_bmse_can_merge(&got, &next, offset_shift_fsb))
+			WARN_ON_ONCE(1);
+	}
+
+	error = xfs_bmap_shift_update_extent(tp, ip, whichfork, &icur, &got,
+			cur, &logflags, new_startoff);
+	if (error)
+		goto del_cursor;
+
+	if (!xfs_iext_prev_extent(ifp, &icur, &got) ||
+	    stop_fsb >= got.br_startoff + got.br_blockcount) {
+		*done = true;
+		goto del_cursor;
+	}
+
+	*next_fsb = got.br_startoff;
+del_cursor:
+	if (cur)
+		xfs_btree_del_cursor(cur, error);
+	if (logflags)
+		xfs_trans_log_inode(tp, ip, logflags);
+	return error;
+}
+
+/*
+ * Splits an extent into two extents at split_fsb block such that it is the
+ * first block of the current_ext. @ext is a target extent to be split.
+ * @split_fsb is a block where the extents is split.  If split_fsb lies in a
+ * hole or the first block of extents, just return 0.
+ */
+int
+xfs_bmap_split_extent(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		split_fsb)
+{
+	int				whichfork = XFS_DATA_FORK;
+	struct xfs_ifork		*ifp = xfs_ifork_ptr(ip, whichfork);
+	struct xfs_btree_cur		*cur = NULL;
+	struct xfs_bmbt_irec		got;
+	struct xfs_bmbt_irec		new; /* split extent */
+	struct xfs_mount		*mp = ip->i_mount;
+	xfs_fsblock_t			gotblkcnt; /* new block count for got */
+	struct xfs_iext_cursor		icur;
+	int				error = 0;
+	int				logflags = 0;
+	int				i = 0;
+
+	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)) ||
+	    XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) {
+		return -EFSCORRUPTED;
+	}
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	/* Read in all the extents */
+	error = xfs_iread_extents(tp, ip, whichfork);
+	if (error)
+		return error;
+
+	/*
+	 * If there are not extents, or split_fsb lies in a hole we are done.
+	 */
+	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &icur, &got) ||
+	    got.br_startoff >= split_fsb)
+		return 0;
+
+	gotblkcnt = split_fsb - got.br_startoff;
+	new.br_startoff = split_fsb;
+	new.br_startblock = got.br_startblock + gotblkcnt;
+	new.br_blockcount = got.br_blockcount - gotblkcnt;
+	new.br_state = got.br_state;
+
+	if (ifp->if_format == XFS_DINODE_FMT_BTREE) {
+		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
+		cur->bc_ino.flags = 0;
+		error = xfs_bmbt_lookup_eq(cur, &got, &i);
+		if (error)
+			goto del_cursor;
+		if (XFS_IS_CORRUPT(mp, i != 1)) {
+			error = -EFSCORRUPTED;
+			goto del_cursor;
+		}
+	}
+
+	got.br_blockcount = gotblkcnt;
+	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), &icur,
+			&got);
+
+	logflags = XFS_ILOG_CORE;
+	if (cur) {
+		error = xfs_bmbt_update(cur, &got);
+		if (error)
+			goto del_cursor;
+	} else
+		logflags |= XFS_ILOG_DEXT;
+
+	/* Add new extent */
+	xfs_iext_next(ifp, &icur);
+	xfs_iext_insert(ip, &icur, &new, 0);
+	ifp->if_nextents++;
+
+	if (cur) {
+		error = xfs_bmbt_lookup_eq(cur, &new, &i);
+		if (error)
+			goto del_cursor;
+		if (XFS_IS_CORRUPT(mp, i != 0)) {
+			error = -EFSCORRUPTED;
+			goto del_cursor;
+		}
+		error = xfs_btree_insert(cur, &i);
+		if (error)
+			goto del_cursor;
+		if (XFS_IS_CORRUPT(mp, i != 1)) {
+			error = -EFSCORRUPTED;
+			goto del_cursor;
+		}
+	}
+
+	/*
+	 * Convert to a btree if necessary.
+	 */
+	if (xfs_bmap_needs_btree(ip, whichfork)) {
+		int tmp_logflags; /* partial log flag return val */
+
+		ASSERT(cur == NULL);
+		error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
+				&tmp_logflags, whichfork);
+		logflags |= tmp_logflags;
+	}
+
+del_cursor:
+	if (cur) {
+		cur->bc_ino.allocated = 0;
+		xfs_btree_del_cursor(cur, error);
+	}
+
+	if (logflags)
+		xfs_trans_log_inode(tp, ip, logflags);
+	return error;
+}
+
+/* Deferred mapping is only for real extents in the data fork. */
+static bool
+xfs_bmap_is_update_needed(
+	struct xfs_bmbt_irec	*bmap)
+{
+	return  bmap->br_startblock != HOLESTARTBLOCK &&
+		bmap->br_startblock != DELAYSTARTBLOCK;
+}
+
+/* Record a bmap intent. */
+static int
+__xfs_bmap_add(
+	struct xfs_trans		*tp,
+	enum xfs_bmap_intent_type	type,
+	struct xfs_inode		*ip,
+	int				whichfork,
+	struct xfs_bmbt_irec		*bmap)
+{
+	struct xfs_bmap_intent		*bi;
+
+	trace_xfs_bmap_defer(tp->t_mountp,
+			XFS_FSB_TO_AGNO(tp->t_mountp, bmap->br_startblock),
+			type,
+			XFS_FSB_TO_AGBNO(tp->t_mountp, bmap->br_startblock),
+			ip->i_ino, whichfork,
+			bmap->br_startoff,
+			bmap->br_blockcount,
+			bmap->br_state);
+
+	bi = kmem_cache_alloc(xfs_bmap_intent_cache, GFP_NOFS | __GFP_NOFAIL);
+	INIT_LIST_HEAD(&bi->bi_list);
+	bi->bi_type = type;
+	bi->bi_owner = ip;
+	bi->bi_whichfork = whichfork;
+	bi->bi_bmap = *bmap;
+
+	xfs_bmap_update_get_group(tp->t_mountp, bi);
+	xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_BMAP, &bi->bi_list);
+	return 0;
+}
+
+/* Map an extent into a file. */
+void
+xfs_bmap_map_extent(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	struct xfs_bmbt_irec	*PREV)
+{
+	if (!xfs_bmap_is_update_needed(PREV))
+		return;
+
+	__xfs_bmap_add(tp, XFS_BMAP_MAP, ip, XFS_DATA_FORK, PREV);
+}
+
+/* Unmap an extent out of a file. */
+void
+xfs_bmap_unmap_extent(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	struct xfs_bmbt_irec	*PREV)
+{
+	if (!xfs_bmap_is_update_needed(PREV))
+		return;
+
+	__xfs_bmap_add(tp, XFS_BMAP_UNMAP, ip, XFS_DATA_FORK, PREV);
+}
+
+/*
+ * Process one of the deferred bmap operations.  We pass back the
+ * btree cursor to maintain our lock on the bmapbt between calls.
+ */
+int
+xfs_bmap_finish_one(
+	struct xfs_trans		*tp,
+	struct xfs_bmap_intent		*bi)
+{
+	struct xfs_bmbt_irec		*bmap = &bi->bi_bmap;
+	int				error = 0;
+
+	ASSERT(tp->t_highest_agno == NULLAGNUMBER);
+
+	trace_xfs_bmap_deferred(tp->t_mountp,
+			XFS_FSB_TO_AGNO(tp->t_mountp, bmap->br_startblock),
+			bi->bi_type,
+			XFS_FSB_TO_AGBNO(tp->t_mountp, bmap->br_startblock),
+			bi->bi_owner->i_ino, bi->bi_whichfork,
+			bmap->br_startoff, bmap->br_blockcount,
+			bmap->br_state);
+
+	if (WARN_ON_ONCE(bi->bi_whichfork != XFS_DATA_FORK))
+		return -EFSCORRUPTED;
+
+	if (XFS_TEST_ERROR(false, tp->t_mountp,
+			XFS_ERRTAG_BMAP_FINISH_ONE))
+		return -EIO;
+
+	switch (bi->bi_type) {
+	case XFS_BMAP_MAP:
+		error = xfs_bmapi_remap(tp, bi->bi_owner, bmap->br_startoff,
+				bmap->br_blockcount, bmap->br_startblock, 0);
+		bmap->br_blockcount = 0;
+		break;
+	case XFS_BMAP_UNMAP:
+		error = __xfs_bunmapi(tp, bi->bi_owner, bmap->br_startoff,
+				&bmap->br_blockcount, XFS_BMAPI_REMAP, 1);
+		break;
+	default:
+		ASSERT(0);
+		error = -EFSCORRUPTED;
+	}
+
+	return error;
+}
+
+/* Check that an inode's extent does not have invalid flags or bad ranges. */
+xfs_failaddr_t
+xfs_bmap_validate_extent(
+	struct xfs_inode	*ip,
+	int			whichfork,
+	struct xfs_bmbt_irec	*irec)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	if (!xfs_verify_fileext(mp, irec->br_startoff, irec->br_blockcount))
+		return __this_address;
+
+	if (XFS_IS_REALTIME_INODE(ip) && whichfork == XFS_DATA_FORK) {
+		if (!xfs_verify_rtext(mp, irec->br_startblock,
+					  irec->br_blockcount))
+			return __this_address;
+	} else {
+		if (!xfs_verify_fsbext(mp, irec->br_startblock,
+					   irec->br_blockcount))
+			return __this_address;
+	}
+	if (irec->br_state != XFS_EXT_NORM && whichfork != XFS_DATA_FORK)
+		return __this_address;
+	return NULL;
+}
+
+int __init
+xfs_bmap_intent_init_cache(void)
+{
+	xfs_bmap_intent_cache = kmem_cache_create("xfs_bmap_intent",
+			sizeof(struct xfs_bmap_intent),
+			0, 0, NULL);
+
+	return xfs_bmap_intent_cache != NULL ? 0 : -ENOMEM;
+}
+
+void
+xfs_bmap_intent_destroy_cache(void)
+{
+	kmem_cache_destroy(xfs_bmap_intent_cache);
+	xfs_bmap_intent_cache = NULL;
+}