xfs: create xfs_bmap_util.[ch]

There is a bunch of code in xfs_bmap.c that is kernel specific and
not shared with userspace. To minimise the difference between the
kernel and userspace code, shift this unshared code to
xfs_bmap_util.c, and the declarations to xfs_bmap_util.h.

The biggest issue here is xfs_bmap_finish() - userspace has it's own
definition of this function, and so we need to move it out of
xfs_bmap.[ch]. This means several other files need to include
xfs_bmap_util.h as well.

It also introduces and interesting dance for the stack switching
code in xfs_bmapi_allocate(). The stack switching/workqueue code is
actually moved to xfs_bmap_util.c, so that userspace can simply use
a #define in a header file to connect the dots without needing to
know about the stack switch code at all.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 834 insertions, 0 deletions

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
new file mode 100644
index 0000000..8e48ddf
--- /dev/null
+++ b/fs/xfs/xfs_bmap_util.c
@@ -0,0 +1,834 @@
+/*
+ * Copyright (c) 2000-2006 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_format.h"
+#include "xfs_bit.h"
+#include "xfs_log.h"
+#include "xfs_inum.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_mount.h"
+#include "xfs_da_btree.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_dinode.h"
+#include "xfs_inode.h"
+#include "xfs_btree.h"
+#include "xfs_extfree_item.h"
+#include "xfs_alloc.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_rtalloc.h"
+#include "xfs_error.h"
+#include "xfs_quota.h"
+#include "xfs_trans_space.h"
+#include "xfs_trace.h"
+
+/* Kernel only BMAP related definitions and functions */
+
+/*
+ * Convert the given file system block to a disk block.  We have to treat it
+ * differently based on whether the file is a real time file or not, because the
+ * bmap code does.
+ */
+xfs_daddr_t
+xfs_fsb_to_db(struct xfs_inode *ip, xfs_fsblock_t fsb)
+{
+	return (XFS_IS_REALTIME_INODE(ip) ? \
+		 (xfs_daddr_t)XFS_FSB_TO_BB((ip)->i_mount, (fsb)) : \
+		 XFS_FSB_TO_DADDR((ip)->i_mount, (fsb)));
+}
+
+/*
+ * Routine to be called at transaction's end by xfs_bmapi, xfs_bunmapi
+ * caller.  Frees all the extents that need freeing, which must be done
+ * last due to locking considerations.  We never free any extents in
+ * the first transaction.
+ *
+ * Return 1 if the given transaction was committed and a new one
+ * started, and 0 otherwise in the committed parameter.
+ */
+int						/* error */
+xfs_bmap_finish(
+	xfs_trans_t		**tp,		/* transaction pointer addr */
+	xfs_bmap_free_t		*flist,		/* i/o: list extents to free */
+	int			*committed)	/* xact committed or not */
+{
+	xfs_efd_log_item_t	*efd;		/* extent free data */
+	xfs_efi_log_item_t	*efi;		/* extent free intention */
+	int			error;		/* error return value */
+	xfs_bmap_free_item_t	*free;		/* free extent item */
+	unsigned int		logres;		/* new log reservation */
+	unsigned int		logcount;	/* new log count */
+	xfs_mount_t		*mp;		/* filesystem mount structure */
+	xfs_bmap_free_item_t	*next;		/* next item on free list */
+	xfs_trans_t		*ntp;		/* new transaction pointer */
+
+	ASSERT((*tp)->t_flags & XFS_TRANS_PERM_LOG_RES);
+	if (flist->xbf_count == 0) {
+		*committed = 0;
+		return 0;
+	}
+	ntp = *tp;
+	efi = xfs_trans_get_efi(ntp, flist->xbf_count);
+	for (free = flist->xbf_first; free; free = free->xbfi_next)
+		xfs_trans_log_efi_extent(ntp, efi, free->xbfi_startblock,
+			free->xbfi_blockcount);
+	logres = ntp->t_log_res;
+	logcount = ntp->t_log_count;
+	ntp = xfs_trans_dup(*tp);
+	error = xfs_trans_commit(*tp, 0);
+	*tp = ntp;
+	*committed = 1;
+	/*
+	 * We have a new transaction, so we should return committed=1,
+	 * even though we're returning an error.
+	 */
+	if (error)
+		return error;
+
+	/*
+	 * transaction commit worked ok so we can drop the extra ticket
+	 * reference that we gained in xfs_trans_dup()
+	 */
+	xfs_log_ticket_put(ntp->t_ticket);
+
+	if ((error = xfs_trans_reserve(ntp, 0, logres, 0, XFS_TRANS_PERM_LOG_RES,
+			logcount)))
+		return error;
+	efd = xfs_trans_get_efd(ntp, efi, flist->xbf_count);
+	for (free = flist->xbf_first; free != NULL; free = next) {
+		next = free->xbfi_next;
+		if ((error = xfs_free_extent(ntp, free->xbfi_startblock,
+				free->xbfi_blockcount))) {
+			/*
+			 * The bmap free list will be cleaned up at a
+			 * higher level.  The EFI will be canceled when
+			 * this transaction is aborted.
+			 * Need to force shutdown here to make sure it
+			 * happens, since this transaction may not be
+			 * dirty yet.
+			 */
+			mp = ntp->t_mountp;
+			if (!XFS_FORCED_SHUTDOWN(mp))
+				xfs_force_shutdown(mp,
+						   (error == EFSCORRUPTED) ?
+						   SHUTDOWN_CORRUPT_INCORE :
+						   SHUTDOWN_META_IO_ERROR);
+			return error;
+		}
+		xfs_trans_log_efd_extent(ntp, efd, free->xbfi_startblock,
+			free->xbfi_blockcount);
+		xfs_bmap_del_free(flist, NULL, free);
+	}
+	return 0;
+}
+
+int
+xfs_bmap_rtalloc(
+	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
+{
+	xfs_alloctype_t	atype = 0;	/* type for allocation routines */
+	int		error;		/* error return value */
+	xfs_mount_t	*mp;		/* mount point structure */
+	xfs_extlen_t	prod = 0;	/* product factor for allocators */
+	xfs_extlen_t	ralen = 0;	/* realtime allocation length */
+	xfs_extlen_t	align;		/* minimum allocation alignment */
+	xfs_rtblock_t	rtb;
+
+	mp = ap->ip->i_mount;
+	align = xfs_get_extsz_hint(ap->ip);
+	prod = align / mp->m_sb.sb_rextsize;
+	error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev,
+					align, 1, ap->eof, 0,
+					ap->conv, &ap->offset, &ap->length);
+	if (error)
+		return error;
+	ASSERT(ap->length);
+	ASSERT(ap->length % mp->m_sb.sb_rextsize == 0);
+
+	/*
+	 * If the offset & length are not perfectly aligned
+	 * then kill prod, it will just get us in trouble.
+	 */
+	if (do_mod(ap->offset, align) || ap->length % align)
+		prod = 1;
+	/*
+	 * Set ralen to be the actual requested length in rtextents.
+	 */
+	ralen = ap->length / mp->m_sb.sb_rextsize;
+	/*
+	 * If the old value was close enough to MAXEXTLEN that
+	 * we rounded up to it, cut it back so it's valid again.
+	 * Note that if it's a really large request (bigger than
+	 * MAXEXTLEN), we don't hear about that number, and can't
+	 * adjust the starting point to match it.
+	 */
+	if (ralen * mp->m_sb.sb_rextsize >= MAXEXTLEN)
+		ralen = MAXEXTLEN / mp->m_sb.sb_rextsize;
+
+	/*
+	 * Lock out other modifications to the RT bitmap inode.
+	 */
+	xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(ap->tp, mp->m_rbmip, XFS_ILOCK_EXCL);
+
+	/*
+	 * If it's an allocation to an empty file at offset 0,
+	 * pick an extent that will space things out in the rt area.
+	 */
+	if (ap->eof && ap->offset == 0) {
+		xfs_rtblock_t uninitialized_var(rtx); /* realtime extent no */
+
+		error = xfs_rtpick_extent(mp, ap->tp, ralen, &rtx);
+		if (error)
+			return error;
+		ap->blkno = rtx * mp->m_sb.sb_rextsize;
+	} else {
+		ap->blkno = 0;
+	}
+
+	xfs_bmap_adjacent(ap);
+
+	/*
+	 * Realtime allocation, done through xfs_rtallocate_extent.
+	 */
+	atype = ap->blkno == 0 ?  XFS_ALLOCTYPE_ANY_AG : XFS_ALLOCTYPE_NEAR_BNO;
+	do_div(ap->blkno, mp->m_sb.sb_rextsize);
+	rtb = ap->blkno;
+	ap->length = ralen;
+	if ((error = xfs_rtallocate_extent(ap->tp, ap->blkno, 1, ap->length,
+				&ralen, atype, ap->wasdel, prod, &rtb)))
+		return error;
+	if (rtb == NULLFSBLOCK && prod > 1 &&
+	    (error = xfs_rtallocate_extent(ap->tp, ap->blkno, 1,
+					   ap->length, &ralen, atype,
+					   ap->wasdel, 1, &rtb)))
+		return error;
+	ap->blkno = rtb;
+	if (ap->blkno != NULLFSBLOCK) {
+		ap->blkno *= mp->m_sb.sb_rextsize;
+		ralen *= mp->m_sb.sb_rextsize;
+		ap->length = ralen;
+		ap->ip->i_d.di_nblocks += ralen;
+		xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
+		if (ap->wasdel)
+			ap->ip->i_delayed_blks -= ralen;
+		/*
+		 * Adjust the disk quota also. This was reserved
+		 * earlier.
+		 */
+		xfs_trans_mod_dquot_byino(ap->tp, ap->ip,
+			ap->wasdel ? XFS_TRANS_DQ_DELRTBCOUNT :
+					XFS_TRANS_DQ_RTBCOUNT, (long) ralen);
+	} else {
+		ap->length = 0;
+	}
+	return 0;
+}
+
+/*
+ * Stack switching interfaces for allocation
+ */
+static void
+xfs_bmapi_allocate_worker(
+	struct work_struct	*work)
+{
+	struct xfs_bmalloca	*args = container_of(work,
+						struct xfs_bmalloca, work);
+	unsigned long		pflags;
+
+	/* we are in a transaction context here */
+	current_set_flags_nested(&pflags, PF_FSTRANS);
+
+	args->result = __xfs_bmapi_allocate(args);
+	complete(args->done);
+
+	current_restore_flags_nested(&pflags, PF_FSTRANS);
+}
+
+/*
+ * Some allocation requests often come in with little stack to work on. Push
+ * them off to a worker thread so there is lots of stack to use. Otherwise just
+ * call directly to avoid the context switch overhead here.
+ */
+int
+xfs_bmapi_allocate(
+	struct xfs_bmalloca	*args)
+{
+	DECLARE_COMPLETION_ONSTACK(done);
+
+	if (!args->stack_switch)
+		return __xfs_bmapi_allocate(args);
+
+
+	args->done = &done;
+	INIT_WORK_ONSTACK(&args->work, xfs_bmapi_allocate_worker);
+	queue_work(xfs_alloc_wq, &args->work);
+	wait_for_completion(&done);
+	return args->result;
+}
+
+/*
+ * Check if the endoff is outside the last extent. If so the caller will grow
+ * the allocation to a stripe unit boundary.  All offsets are considered outside
+ * the end of file for an empty fork, so 1 is returned in *eof in that case.
+ */
+int
+xfs_bmap_eof(
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		endoff,
+	int			whichfork,
+	int			*eof)
+{
+	struct xfs_bmbt_irec	rec;
+	int			error;
+
+	error = xfs_bmap_last_extent(NULL, ip, whichfork, &rec, eof);
+	if (error || *eof)
+		return error;
+
+	*eof = endoff >= rec.br_startoff + rec.br_blockcount;
+	return 0;
+}
+
+/*
+ * Extent tree block counting routines.
+ */
+
+/*
+ * Count leaf blocks given a range of extent records.
+ */
+STATIC void
+xfs_bmap_count_leaves(
+	xfs_ifork_t		*ifp,
+	xfs_extnum_t		idx,
+	int			numrecs,
+	int			*count)
+{
+	int		b;
+
+	for (b = 0; b < numrecs; b++) {
+		xfs_bmbt_rec_host_t *frp = xfs_iext_get_ext(ifp, idx + b);
+		*count += xfs_bmbt_get_blockcount(frp);
+	}
+}
+
+/*
+ * Count leaf blocks given a range of extent records originally
+ * in btree format.
+ */
+STATIC void
+xfs_bmap_disk_count_leaves(
+	struct xfs_mount	*mp,
+	struct xfs_btree_block	*block,
+	int			numrecs,
+	int			*count)
+{
+	int		b;
+	xfs_bmbt_rec_t	*frp;
+
+	for (b = 1; b <= numrecs; b++) {
+		frp = XFS_BMBT_REC_ADDR(mp, block, b);
+		*count += xfs_bmbt_disk_get_blockcount(frp);
+	}
+}
+
+/*
+ * Recursively walks each level of a btree
+ * to count total fsblocks is use.
+ */
+STATIC int                                     /* error */
+xfs_bmap_count_tree(
+	xfs_mount_t     *mp,            /* file system mount point */
+	xfs_trans_t     *tp,            /* transaction pointer */
+	xfs_ifork_t	*ifp,		/* inode fork pointer */
+	xfs_fsblock_t   blockno,	/* file system block number */
+	int             levelin,	/* level in btree */
+	int		*count)		/* Count of blocks */
+{
+	int			error;
+	xfs_buf_t		*bp, *nbp;
+	int			level = levelin;
+	__be64			*pp;
+	xfs_fsblock_t           bno = blockno;
+	xfs_fsblock_t		nextbno;
+	struct xfs_btree_block	*block, *nextblock;
+	int			numrecs;
+
+	error = xfs_btree_read_bufl(mp, tp, bno, 0, &bp, XFS_BMAP_BTREE_REF,
+						&xfs_bmbt_buf_ops);
+	if (error)
+		return error;
+	*count += 1;
+	block = XFS_BUF_TO_BLOCK(bp);
+
+	if (--level) {
+		/* Not at node above leaves, count this level of nodes */
+		nextbno = be64_to_cpu(block->bb_u.l.bb_rightsib);
+		while (nextbno != NULLFSBLOCK) {
+			error = xfs_btree_read_bufl(mp, tp, nextbno, 0, &nbp,
+						XFS_BMAP_BTREE_REF,
+						&xfs_bmbt_buf_ops);
+			if (error)
+				return error;
+			*count += 1;
+			nextblock = XFS_BUF_TO_BLOCK(nbp);
+			nextbno = be64_to_cpu(nextblock->bb_u.l.bb_rightsib);
+			xfs_trans_brelse(tp, nbp);
+		}
+
+		/* Dive to the next level */
+		pp = XFS_BMBT_PTR_ADDR(mp, block, 1, mp->m_bmap_dmxr[1]);
+		bno = be64_to_cpu(*pp);
+		if (unlikely((error =
+		     xfs_bmap_count_tree(mp, tp, ifp, bno, level, count)) < 0)) {
+			xfs_trans_brelse(tp, bp);
+			XFS_ERROR_REPORT("xfs_bmap_count_tree(1)",
+					 XFS_ERRLEVEL_LOW, mp);
+			return XFS_ERROR(EFSCORRUPTED);
+		}
+		xfs_trans_brelse(tp, bp);
+	} else {
+		/* count all level 1 nodes and their leaves */
+		for (;;) {
+			nextbno = be64_to_cpu(block->bb_u.l.bb_rightsib);
+			numrecs = be16_to_cpu(block->bb_numrecs);
+			xfs_bmap_disk_count_leaves(mp, block, numrecs, count);
+			xfs_trans_brelse(tp, bp);
+			if (nextbno == NULLFSBLOCK)
+				break;
+			bno = nextbno;
+			error = xfs_btree_read_bufl(mp, tp, bno, 0, &bp,
+						XFS_BMAP_BTREE_REF,
+						&xfs_bmbt_buf_ops);
+			if (error)
+				return error;
+			*count += 1;
+			block = XFS_BUF_TO_BLOCK(bp);
+		}
+	}
+	return 0;
+}
+
+/*
+ * Count fsblocks of the given fork.
+ */
+int						/* error */
+xfs_bmap_count_blocks(
+	xfs_trans_t		*tp,		/* transaction pointer */
+	xfs_inode_t		*ip,		/* incore inode */
+	int			whichfork,	/* data or attr fork */
+	int			*count)		/* out: count of blocks */
+{
+	struct xfs_btree_block	*block;	/* current btree block */
+	xfs_fsblock_t		bno;	/* block # of "block" */
+	xfs_ifork_t		*ifp;	/* fork structure */
+	int			level;	/* btree level, for checking */
+	xfs_mount_t		*mp;	/* file system mount structure */
+	__be64			*pp;	/* pointer to block address */
+
+	bno = NULLFSBLOCK;
+	mp = ip->i_mount;
+	ifp = XFS_IFORK_PTR(ip, whichfork);
+	if ( XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_EXTENTS ) {
+		xfs_bmap_count_leaves(ifp, 0,
+			ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t),
+			count);
+		return 0;
+	}
+
+	/*
+	 * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
+	 */
+	block = ifp->if_broot;
+	level = be16_to_cpu(block->bb_level);
+	ASSERT(level > 0);
+	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
+	bno = be64_to_cpu(*pp);
+	ASSERT(bno != NULLDFSBNO);
+	ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
+	ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);
+
+	if (unlikely(xfs_bmap_count_tree(mp, tp, ifp, bno, level, count) < 0)) {
+		XFS_ERROR_REPORT("xfs_bmap_count_blocks(2)", XFS_ERRLEVEL_LOW,
+				 mp);
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+
+	return 0;
+}
+
+/*
+ * returns 1 for success, 0 if we failed to map the extent.
+ */
+STATIC int
+xfs_getbmapx_fix_eof_hole(
+	xfs_inode_t		*ip,		/* xfs incore inode pointer */
+	struct getbmapx		*out,		/* output structure */
+	int			prealloced,	/* this is a file with
+						 * preallocated data space */
+	__int64_t		end,		/* last block requested */
+	xfs_fsblock_t		startblock)
+{
+	__int64_t		fixlen;
+	xfs_mount_t		*mp;		/* file system mount point */
+	xfs_ifork_t		*ifp;		/* inode fork pointer */
+	xfs_extnum_t		lastx;		/* last extent pointer */
+	xfs_fileoff_t		fileblock;
+
+	if (startblock == HOLESTARTBLOCK) {
+		mp = ip->i_mount;
+		out->bmv_block = -1;
+		fixlen = XFS_FSB_TO_BB(mp, XFS_B_TO_FSB(mp, XFS_ISIZE(ip)));
+		fixlen -= out->bmv_offset;
+		if (prealloced && out->bmv_offset + out->bmv_length == end) {
+			/* Came to hole at EOF. Trim it. */
+			if (fixlen <= 0)
+				return 0;
+			out->bmv_length = fixlen;
+		}
+	} else {
+		if (startblock == DELAYSTARTBLOCK)
+			out->bmv_block = -2;
+		else
+			out->bmv_block = xfs_fsb_to_db(ip, startblock);
+		fileblock = XFS_BB_TO_FSB(ip->i_mount, out->bmv_offset);
+		ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
+		if (xfs_iext_bno_to_ext(ifp, fileblock, &lastx) &&
+		   (lastx == (ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t))-1))
+			out->bmv_oflags |= BMV_OF_LAST;
+	}
+
+	return 1;
+}
+
+/*
+ * Get inode's extents as described in bmv, and format for output.
+ * Calls formatter to fill the user's buffer until all extents
+ * are mapped, until the passed-in bmv->bmv_count slots have
+ * been filled, or until the formatter short-circuits the loop,
+ * if it is tracking filled-in extents on its own.
+ */
+int						/* error code */
+xfs_getbmap(
+	xfs_inode_t		*ip,
+	struct getbmapx		*bmv,		/* user bmap structure */
+	xfs_bmap_format_t	formatter,	/* format to user */
+	void			*arg)		/* formatter arg */
+{
+	__int64_t		bmvend;		/* last block requested */
+	int			error = 0;	/* return value */
+	__int64_t		fixlen;		/* length for -1 case */
+	int			i;		/* extent number */
+	int			lock;		/* lock state */
+	xfs_bmbt_irec_t		*map;		/* buffer for user's data */
+	xfs_mount_t		*mp;		/* file system mount point */
+	int			nex;		/* # of user extents can do */
+	int			nexleft;	/* # of user extents left */
+	int			subnex;		/* # of bmapi's can do */
+	int			nmap;		/* number of map entries */
+	struct getbmapx		*out;		/* output structure */
+	int			whichfork;	/* data or attr fork */
+	int			prealloced;	/* this is a file with
+						 * preallocated data space */
+	int			iflags;		/* interface flags */
+	int			bmapi_flags;	/* flags for xfs_bmapi */
+	int			cur_ext = 0;
+
+	mp = ip->i_mount;
+	iflags = bmv->bmv_iflags;
+	whichfork = iflags & BMV_IF_ATTRFORK ? XFS_ATTR_FORK : XFS_DATA_FORK;
+
+	if (whichfork == XFS_ATTR_FORK) {
+		if (XFS_IFORK_Q(ip)) {
+			if (ip->i_d.di_aformat != XFS_DINODE_FMT_EXTENTS &&
+			    ip->i_d.di_aformat != XFS_DINODE_FMT_BTREE &&
+			    ip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL)
+				return XFS_ERROR(EINVAL);
+		} else if (unlikely(
+			   ip->i_d.di_aformat != 0 &&
+			   ip->i_d.di_aformat != XFS_DINODE_FMT_EXTENTS)) {
+			XFS_ERROR_REPORT("xfs_getbmap", XFS_ERRLEVEL_LOW,
+					 ip->i_mount);
+			return XFS_ERROR(EFSCORRUPTED);
+		}
+
+		prealloced = 0;
+		fixlen = 1LL << 32;
+	} else {
+		if (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS &&
+		    ip->i_d.di_format != XFS_DINODE_FMT_BTREE &&
+		    ip->i_d.di_format != XFS_DINODE_FMT_LOCAL)
+			return XFS_ERROR(EINVAL);
+
+		if (xfs_get_extsz_hint(ip) ||
+		    ip->i_d.di_flags & (XFS_DIFLAG_PREALLOC|XFS_DIFLAG_APPEND)){
+			prealloced = 1;
+			fixlen = mp->m_super->s_maxbytes;
+		} else {
+			prealloced = 0;
+			fixlen = XFS_ISIZE(ip);
+		}
+	}
+
+	if (bmv->bmv_length == -1) {
+		fixlen = XFS_FSB_TO_BB(mp, XFS_B_TO_FSB(mp, fixlen));
+		bmv->bmv_length =
+			max_t(__int64_t, fixlen - bmv->bmv_offset, 0);
+	} else if (bmv->bmv_length == 0) {
+		bmv->bmv_entries = 0;
+		return 0;
+	} else if (bmv->bmv_length < 0) {
+		return XFS_ERROR(EINVAL);
+	}
+
+	nex = bmv->bmv_count - 1;
+	if (nex <= 0)
+		return XFS_ERROR(EINVAL);
+	bmvend = bmv->bmv_offset + bmv->bmv_length;
+
+
+	if (bmv->bmv_count > ULONG_MAX / sizeof(struct getbmapx))
+		return XFS_ERROR(ENOMEM);
+	out = kmem_zalloc(bmv->bmv_count * sizeof(struct getbmapx), KM_MAYFAIL);
+	if (!out) {
+		out = kmem_zalloc_large(bmv->bmv_count *
+					sizeof(struct getbmapx));
+		if (!out)
+			return XFS_ERROR(ENOMEM);
+	}
+
+	xfs_ilock(ip, XFS_IOLOCK_SHARED);
+	if (whichfork == XFS_DATA_FORK && !(iflags & BMV_IF_DELALLOC)) {
+		if (ip->i_delayed_blks || XFS_ISIZE(ip) > ip->i_d.di_size) {
+			error = -filemap_write_and_wait(VFS_I(ip)->i_mapping);
+			if (error)
+				goto out_unlock_iolock;
+		}
+		/*
+		 * even after flushing the inode, there can still be delalloc
+		 * blocks on the inode beyond EOF due to speculative
+		 * preallocation. These are not removed until the release
+		 * function is called or the inode is inactivated. Hence we
+		 * cannot assert here that ip->i_delayed_blks == 0.
+		 */
+	}
+
+	lock = xfs_ilock_map_shared(ip);
+
+	/*
+	 * Don't let nex be bigger than the number of extents
+	 * we can have assuming alternating holes and real extents.
+	 */
+	if (nex > XFS_IFORK_NEXTENTS(ip, whichfork) * 2 + 1)
+		nex = XFS_IFORK_NEXTENTS(ip, whichfork) * 2 + 1;
+
+	bmapi_flags = xfs_bmapi_aflag(whichfork);
+	if (!(iflags & BMV_IF_PREALLOC))
+		bmapi_flags |= XFS_BMAPI_IGSTATE;
+
+	/*
+	 * Allocate enough space to handle "subnex" maps at a time.
+	 */
+	error = ENOMEM;
+	subnex = 16;
+	map = kmem_alloc(subnex * sizeof(*map), KM_MAYFAIL | KM_NOFS);
+	if (!map)
+		goto out_unlock_ilock;
+
+	bmv->bmv_entries = 0;
+
+	if (XFS_IFORK_NEXTENTS(ip, whichfork) == 0 &&
+	    (whichfork == XFS_ATTR_FORK || !(iflags & BMV_IF_DELALLOC))) {
+		error = 0;
+		goto out_free_map;
+	}
+
+	nexleft = nex;
+
+	do {
+		nmap = (nexleft > subnex) ? subnex : nexleft;
+		error = xfs_bmapi_read(ip, XFS_BB_TO_FSBT(mp, bmv->bmv_offset),
+				       XFS_BB_TO_FSB(mp, bmv->bmv_length),
+				       map, &nmap, bmapi_flags);
+		if (error)
+			goto out_free_map;
+		ASSERT(nmap <= subnex);
+
+		for (i = 0; i < nmap && nexleft && bmv->bmv_length; i++) {
+			out[cur_ext].bmv_oflags = 0;
+			if (map[i].br_state == XFS_EXT_UNWRITTEN)
+				out[cur_ext].bmv_oflags |= BMV_OF_PREALLOC;
+			else if (map[i].br_startblock == DELAYSTARTBLOCK)
+				out[cur_ext].bmv_oflags |= BMV_OF_DELALLOC;
+			out[cur_ext].bmv_offset =
+				XFS_FSB_TO_BB(mp, map[i].br_startoff);
+			out[cur_ext].bmv_length =
+				XFS_FSB_TO_BB(mp, map[i].br_blockcount);
+			out[cur_ext].bmv_unused1 = 0;
+			out[cur_ext].bmv_unused2 = 0;
+
+			/*
+			 * delayed allocation extents that start beyond EOF can
+			 * occur due to speculative EOF allocation when the
+			 * delalloc extent is larger than the largest freespace
+			 * extent at conversion time. These extents cannot be
+			 * converted by data writeback, so can exist here even
+			 * if we are not supposed to be finding delalloc
+			 * extents.
+			 */
+			if (map[i].br_startblock == DELAYSTARTBLOCK &&
+			    map[i].br_startoff <= XFS_B_TO_FSB(mp, XFS_ISIZE(ip)))
+				ASSERT((iflags & BMV_IF_DELALLOC) != 0);
+
+                        if (map[i].br_startblock == HOLESTARTBLOCK &&
+			    whichfork == XFS_ATTR_FORK) {
+				/* came to the end of attribute fork */
+				out[cur_ext].bmv_oflags |= BMV_OF_LAST;
+				goto out_free_map;
+			}
+
+			if (!xfs_getbmapx_fix_eof_hole(ip, &out[cur_ext],
+					prealloced, bmvend,
+					map[i].br_startblock))
+				goto out_free_map;
+
+			bmv->bmv_offset =
+				out[cur_ext].bmv_offset +
+				out[cur_ext].bmv_length;
+			bmv->bmv_length =
+				max_t(__int64_t, 0, bmvend - bmv->bmv_offset);
+
+			/*
+			 * In case we don't want to return the hole,
+			 * don't increase cur_ext so that we can reuse
+			 * it in the next loop.
+			 */
+			if ((iflags & BMV_IF_NO_HOLES) &&
+			    map[i].br_startblock == HOLESTARTBLOCK) {
+				memset(&out[cur_ext], 0, sizeof(out[cur_ext]));
+				continue;
+			}
+
+			nexleft--;
+			bmv->bmv_entries++;
+			cur_ext++;
+		}
+	} while (nmap && nexleft && bmv->bmv_length);
+
+ out_free_map:
+	kmem_free(map);
+ out_unlock_ilock:
+	xfs_iunlock_map_shared(ip, lock);
+ out_unlock_iolock:
+	xfs_iunlock(ip, XFS_IOLOCK_SHARED);
+
+	for (i = 0; i < cur_ext; i++) {
+		int full = 0;	/* user array is full */
+
+		/* format results & advance arg */
+		error = formatter(&arg, &out[i], &full);
+		if (error || full)
+			break;
+	}
+
+	if (is_vmalloc_addr(out))
+		kmem_free_large(out);
+	else
+		kmem_free(out);
+	return error;
+}
+
+/*
+ * dead simple method of punching delalyed allocation blocks from a range in
+ * the inode. Walks a block at a time so will be slow, but is only executed in
+ * rare error cases so the overhead is not critical. This will alays punch out
+ * both the start and end blocks, even if the ranges only partially overlap
+ * them, so it is up to the caller to ensure that partial blocks are not
+ * passed in.
+ */
+int
+xfs_bmap_punch_delalloc_range(
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		start_fsb,
+	xfs_fileoff_t		length)
+{
+	xfs_fileoff_t		remaining = length;
+	int			error = 0;
+
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+
+	do {
+		int		done;
+		xfs_bmbt_irec_t	imap;
+		int		nimaps = 1;
+		xfs_fsblock_t	firstblock;
+		xfs_bmap_free_t flist;
+
+		/*
+		 * Map the range first and check that it is a delalloc extent
+		 * before trying to unmap the range. Otherwise we will be
+		 * trying to remove a real extent (which requires a
+		 * transaction) or a hole, which is probably a bad idea...
+		 */
+		error = xfs_bmapi_read(ip, start_fsb, 1, &imap, &nimaps,
+				       XFS_BMAPI_ENTIRE);
+
+		if (error) {
+			/* something screwed, just bail */
+			if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+				xfs_alert(ip->i_mount,
+			"Failed delalloc mapping lookup ino %lld fsb %lld.",
+						ip->i_ino, start_fsb);
+			}
+			break;
+		}
+		if (!nimaps) {
+			/* nothing there */
+			goto next_block;
+		}
+		if (imap.br_startblock != DELAYSTARTBLOCK) {
+			/* been converted, ignore */
+			goto next_block;
+		}
+		WARN_ON(imap.br_blockcount == 0);
+
+		/*
+		 * Note: while we initialise the firstblock/flist pair, they
+		 * should never be used because blocks should never be
+		 * allocated or freed for a delalloc extent and hence we need
+		 * don't cancel or finish them after the xfs_bunmapi() call.
+		 */
+		xfs_bmap_init(&flist, &firstblock);
+		error = xfs_bunmapi(NULL, ip, start_fsb, 1, 0, 1, &firstblock,
+					&flist, &done);
+		if (error)
+			break;
+
+		ASSERT(!flist.xbf_count && !flist.xbf_first);
+next_block:
+		start_fsb++;
+		remaining--;
+	} while(remaining > 0);
+
+	return error;
+}