init android origin source code

1 files changed, 756 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/fs/xfs/xfs_iomap.c b/ANDROID_3.4.5/fs/xfs/xfs_iomap.c
new file mode 100644
index 00000000..71a46450
--- /dev/null
+++ b/ANDROID_3.4.5/fs/xfs/xfs_iomap.c
@@ -0,0 +1,756 @@
+/*
+ * 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_bit.h"
+#include "xfs_log.h"
+#include "xfs_inum.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_alloc.h"
+#include "xfs_quota.h"
+#include "xfs_mount.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_inode_item.h"
+#include "xfs_btree.h"
+#include "xfs_bmap.h"
+#include "xfs_rtalloc.h"
+#include "xfs_error.h"
+#include "xfs_itable.h"
+#include "xfs_rw.h"
+#include "xfs_attr.h"
+#include "xfs_buf_item.h"
+#include "xfs_trans_space.h"
+#include "xfs_utils.h"
+#include "xfs_iomap.h"
+#include "xfs_trace.h"
+
+
+#define XFS_WRITEIO_ALIGN(mp,off)	(((off) >> mp->m_writeio_log) \
+						<< mp->m_writeio_log)
+#define XFS_WRITE_IMAPS		XFS_BMAP_MAX_NMAP
+
+STATIC int
+xfs_iomap_eof_align_last_fsb(
+	xfs_mount_t	*mp,
+	xfs_inode_t	*ip,
+	xfs_extlen_t	extsize,
+	xfs_fileoff_t	*last_fsb)
+{
+	xfs_fileoff_t	new_last_fsb = 0;
+	xfs_extlen_t	align = 0;
+	int		eof, error;
+
+	if (!XFS_IS_REALTIME_INODE(ip)) {
+		/*
+		 * Round up the allocation request to a stripe unit
+		 * (m_dalign) boundary if the file size is >= stripe unit
+		 * size, and we are allocating past the allocation eof.
+		 *
+		 * If mounted with the "-o swalloc" option the alignment is
+		 * increased from the strip unit size to the stripe width.
+		 */
+		if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
+			align = mp->m_swidth;
+		else if (mp->m_dalign)
+			align = mp->m_dalign;
+
+		if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
+			new_last_fsb = roundup_64(*last_fsb, align);
+	}
+
+	/*
+	 * Always round up the allocation request to an extent boundary
+	 * (when file on a real-time subvolume or has di_extsize hint).
+	 */
+	if (extsize) {
+		if (new_last_fsb)
+			align = roundup_64(new_last_fsb, extsize);
+		else
+			align = extsize;
+		new_last_fsb = roundup_64(*last_fsb, align);
+	}
+
+	if (new_last_fsb) {
+		error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
+		if (error)
+			return error;
+		if (eof)
+			*last_fsb = new_last_fsb;
+	}
+	return 0;
+}
+
+STATIC int
+xfs_alert_fsblock_zero(
+	xfs_inode_t	*ip,
+	xfs_bmbt_irec_t	*imap)
+{
+	xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
+			"Access to block zero in inode %llu "
+			"start_block: %llx start_off: %llx "
+			"blkcnt: %llx extent-state: %x\n",
+		(unsigned long long)ip->i_ino,
+		(unsigned long long)imap->br_startblock,
+		(unsigned long long)imap->br_startoff,
+		(unsigned long long)imap->br_blockcount,
+		imap->br_state);
+	return EFSCORRUPTED;
+}
+
+int
+xfs_iomap_write_direct(
+	xfs_inode_t	*ip,
+	xfs_off_t	offset,
+	size_t		count,
+	xfs_bmbt_irec_t *imap,
+	int		nmaps)
+{
+	xfs_mount_t	*mp = ip->i_mount;
+	xfs_fileoff_t	offset_fsb;
+	xfs_fileoff_t	last_fsb;
+	xfs_filblks_t	count_fsb, resaligned;
+	xfs_fsblock_t	firstfsb;
+	xfs_extlen_t	extsz, temp;
+	int		nimaps;
+	int		bmapi_flag;
+	int		quota_flag;
+	int		rt;
+	xfs_trans_t	*tp;
+	xfs_bmap_free_t free_list;
+	uint		qblocks, resblks, resrtextents;
+	int		committed;
+	int		error;
+
+	/*
+	 * Make sure that the dquots are there. This doesn't hold
+	 * the ilock across a disk read.
+	 */
+	error = xfs_qm_dqattach_locked(ip, 0);
+	if (error)
+		return XFS_ERROR(error);
+
+	rt = XFS_IS_REALTIME_INODE(ip);
+	extsz = xfs_get_extsz_hint(ip);
+
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
+	if ((offset + count) > XFS_ISIZE(ip)) {
+		error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
+		if (error)
+			goto error_out;
+	} else {
+		if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
+			last_fsb = MIN(last_fsb, (xfs_fileoff_t)
+					imap->br_blockcount +
+					imap->br_startoff);
+	}
+	count_fsb = last_fsb - offset_fsb;
+	ASSERT(count_fsb > 0);
+
+	resaligned = count_fsb;
+	if (unlikely(extsz)) {
+		if ((temp = do_mod(offset_fsb, extsz)))
+			resaligned += temp;
+		if ((temp = do_mod(resaligned, extsz)))
+			resaligned += extsz - temp;
+	}
+
+	if (unlikely(rt)) {
+		resrtextents = qblocks = resaligned;
+		resrtextents /= mp->m_sb.sb_rextsize;
+		resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
+		quota_flag = XFS_QMOPT_RES_RTBLKS;
+	} else {
+		resrtextents = 0;
+		resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+		quota_flag = XFS_QMOPT_RES_REGBLKS;
+	}
+
+	/*
+	 * Allocate and setup the transaction
+	 */
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
+	error = xfs_trans_reserve(tp, resblks,
+			XFS_WRITE_LOG_RES(mp), resrtextents,
+			XFS_TRANS_PERM_LOG_RES,
+			XFS_WRITE_LOG_COUNT);
+	/*
+	 * Check for running out of space, note: need lock to return
+	 */
+	if (error)
+		xfs_trans_cancel(tp, 0);
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	if (error)
+		goto error_out;
+
+	error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
+	if (error)
+		goto error1;
+
+	xfs_trans_ijoin(tp, ip, 0);
+
+	bmapi_flag = 0;
+	if (offset < XFS_ISIZE(ip) || extsz)
+		bmapi_flag |= XFS_BMAPI_PREALLOC;
+
+	/*
+	 * From this point onwards we overwrite the imap pointer that the
+	 * caller gave to us.
+	 */
+	xfs_bmap_init(&free_list, &firstfsb);
+	nimaps = 1;
+	error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
+				&firstfsb, 0, imap, &nimaps, &free_list);
+	if (error)
+		goto error0;
+
+	/*
+	 * Complete the transaction
+	 */
+	error = xfs_bmap_finish(&tp, &free_list, &committed);
+	if (error)
+		goto error0;
+	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
+	if (error)
+		goto error_out;
+
+	/*
+	 * Copy any maps to caller's array and return any error.
+	 */
+	if (nimaps == 0) {
+		error = ENOSPC;
+		goto error_out;
+	}
+
+	if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) {
+		error = xfs_alert_fsblock_zero(ip, imap);
+		goto error_out;
+	}
+
+	return 0;
+
+error0:	/* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
+	xfs_bmap_cancel(&free_list);
+	xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
+
+error1:	/* Just cancel transaction */
+	xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
+
+error_out:
+	return XFS_ERROR(error);
+}
+
+/*
+ * If the caller is doing a write at the end of the file, then extend the
+ * allocation out to the file system's write iosize.  We clean up any extra
+ * space left over when the file is closed in xfs_inactive().
+ *
+ * If we find we already have delalloc preallocation beyond EOF, don't do more
+ * preallocation as it it not needed.
+ */
+STATIC int
+xfs_iomap_eof_want_preallocate(
+	xfs_mount_t	*mp,
+	xfs_inode_t	*ip,
+	xfs_off_t	offset,
+	size_t		count,
+	xfs_bmbt_irec_t *imap,
+	int		nimaps,
+	int		*prealloc)
+{
+	xfs_fileoff_t   start_fsb;
+	xfs_filblks_t   count_fsb;
+	xfs_fsblock_t	firstblock;
+	int		n, error, imaps;
+	int		found_delalloc = 0;
+
+	*prealloc = 0;
+	if (offset + count <= XFS_ISIZE(ip))
+		return 0;
+
+	/*
+	 * If there are any real blocks past eof, then don't
+	 * do any speculative allocation.
+	 */
+	start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
+	count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
+	while (count_fsb > 0) {
+		imaps = nimaps;
+		firstblock = NULLFSBLOCK;
+		error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
+				       0);
+		if (error)
+			return error;
+		for (n = 0; n < imaps; n++) {
+			if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
+			    (imap[n].br_startblock != DELAYSTARTBLOCK))
+				return 0;
+			start_fsb += imap[n].br_blockcount;
+			count_fsb -= imap[n].br_blockcount;
+
+			if (imap[n].br_startblock == DELAYSTARTBLOCK)
+				found_delalloc = 1;
+		}
+	}
+	if (!found_delalloc)
+		*prealloc = 1;
+	return 0;
+}
+
+/*
+ * If we don't have a user specified preallocation size, dynamically increase
+ * the preallocation size as the size of the file grows. Cap the maximum size
+ * at a single extent or less if the filesystem is near full. The closer the
+ * filesystem is to full, the smaller the maximum prealocation.
+ */
+STATIC xfs_fsblock_t
+xfs_iomap_prealloc_size(
+	struct xfs_mount	*mp,
+	struct xfs_inode	*ip)
+{
+	xfs_fsblock_t		alloc_blocks = 0;
+
+	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
+		int shift = 0;
+		int64_t freesp;
+
+		/*
+		 * rounddown_pow_of_two() returns an undefined result
+		 * if we pass in alloc_blocks = 0. Hence the "+ 1" to
+		 * ensure we always pass in a non-zero value.
+		 */
+		alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1;
+		alloc_blocks = XFS_FILEOFF_MIN(MAXEXTLEN,
+					rounddown_pow_of_two(alloc_blocks));
+
+		xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
+		freesp = mp->m_sb.sb_fdblocks;
+		if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
+			shift = 2;
+			if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
+				shift++;
+			if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
+				shift++;
+			if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
+				shift++;
+			if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
+				shift++;
+		}
+		if (shift)
+			alloc_blocks >>= shift;
+	}
+
+	if (alloc_blocks < mp->m_writeio_blocks)
+		alloc_blocks = mp->m_writeio_blocks;
+
+	return alloc_blocks;
+}
+
+int
+xfs_iomap_write_delay(
+	xfs_inode_t	*ip,
+	xfs_off_t	offset,
+	size_t		count,
+	xfs_bmbt_irec_t *ret_imap)
+{
+	xfs_mount_t	*mp = ip->i_mount;
+	xfs_fileoff_t	offset_fsb;
+	xfs_fileoff_t	last_fsb;
+	xfs_off_t	aligned_offset;
+	xfs_fileoff_t	ioalign;
+	xfs_extlen_t	extsz;
+	int		nimaps;
+	xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
+	int		prealloc, flushed = 0;
+	int		error;
+
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+
+	/*
+	 * Make sure that the dquots are there. This doesn't hold
+	 * the ilock across a disk read.
+	 */
+	error = xfs_qm_dqattach_locked(ip, 0);
+	if (error)
+		return XFS_ERROR(error);
+
+	extsz = xfs_get_extsz_hint(ip);
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+
+
+	error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
+				imap, XFS_WRITE_IMAPS, &prealloc);
+	if (error)
+		return error;
+
+retry:
+	if (prealloc) {
+		xfs_fsblock_t	alloc_blocks = xfs_iomap_prealloc_size(mp, ip);
+
+		aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
+		ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
+		last_fsb = ioalign + alloc_blocks;
+	} else {
+		last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
+	}
+
+	if (prealloc || extsz) {
+		error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
+		if (error)
+			return error;
+	}
+
+	nimaps = XFS_WRITE_IMAPS;
+	error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
+				imap, &nimaps, XFS_BMAPI_ENTIRE);
+	switch (error) {
+	case 0:
+	case ENOSPC:
+	case EDQUOT:
+		break;
+	default:
+		return XFS_ERROR(error);
+	}
+
+	/*
+	 * If bmapi returned us nothing, we got either ENOSPC or EDQUOT.  For
+	 * ENOSPC, * flush all other inodes with delalloc blocks to free up
+	 * some of the excess reserved metadata space. For both cases, retry
+	 * without EOF preallocation.
+	 */
+	if (nimaps == 0) {
+		trace_xfs_delalloc_enospc(ip, offset, count);
+		if (flushed)
+			return XFS_ERROR(error ? error : ENOSPC);
+
+		if (error == ENOSPC) {
+			xfs_iunlock(ip, XFS_ILOCK_EXCL);
+			xfs_flush_inodes(ip);
+			xfs_ilock(ip, XFS_ILOCK_EXCL);
+		}
+
+		flushed = 1;
+		error = 0;
+		prealloc = 0;
+		goto retry;
+	}
+
+	if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
+		return xfs_alert_fsblock_zero(ip, &imap[0]);
+
+	*ret_imap = imap[0];
+	return 0;
+}
+
+/*
+ * Pass in a delayed allocate extent, convert it to real extents;
+ * return to the caller the extent we create which maps on top of
+ * the originating callers request.
+ *
+ * Called without a lock on the inode.
+ *
+ * We no longer bother to look at the incoming map - all we have to
+ * guarantee is that whatever we allocate fills the required range.
+ */
+int
+xfs_iomap_write_allocate(
+	xfs_inode_t	*ip,
+	xfs_off_t	offset,
+	size_t		count,
+	xfs_bmbt_irec_t *imap)
+{
+	xfs_mount_t	*mp = ip->i_mount;
+	xfs_fileoff_t	offset_fsb, last_block;
+	xfs_fileoff_t	end_fsb, map_start_fsb;
+	xfs_fsblock_t	first_block;
+	xfs_bmap_free_t	free_list;
+	xfs_filblks_t	count_fsb;
+	xfs_trans_t	*tp;
+	int		nimaps, committed;
+	int		error = 0;
+	int		nres;
+
+	/*
+	 * Make sure that the dquots are there.
+	 */
+	error = xfs_qm_dqattach(ip, 0);
+	if (error)
+		return XFS_ERROR(error);
+
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	count_fsb = imap->br_blockcount;
+	map_start_fsb = imap->br_startoff;
+
+	XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
+
+	while (count_fsb != 0) {
+		/*
+		 * Set up a transaction with which to allocate the
+		 * backing store for the file.  Do allocations in a
+		 * loop until we get some space in the range we are
+		 * interested in.  The other space that might be allocated
+		 * is in the delayed allocation extent on which we sit
+		 * but before our buffer starts.
+		 */
+
+		nimaps = 0;
+		while (nimaps == 0) {
+			tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
+			tp->t_flags |= XFS_TRANS_RESERVE;
+			nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
+			error = xfs_trans_reserve(tp, nres,
+					XFS_WRITE_LOG_RES(mp),
+					0, XFS_TRANS_PERM_LOG_RES,
+					XFS_WRITE_LOG_COUNT);
+			if (error) {
+				xfs_trans_cancel(tp, 0);
+				return XFS_ERROR(error);
+			}
+			xfs_ilock(ip, XFS_ILOCK_EXCL);
+			xfs_trans_ijoin(tp, ip, 0);
+
+			xfs_bmap_init(&free_list, &first_block);
+
+			/*
+			 * it is possible that the extents have changed since
+			 * we did the read call as we dropped the ilock for a
+			 * while. We have to be careful about truncates or hole
+			 * punchs here - we are not allowed to allocate
+			 * non-delalloc blocks here.
+			 *
+			 * The only protection against truncation is the pages
+			 * for the range we are being asked to convert are
+			 * locked and hence a truncate will block on them
+			 * first.
+			 *
+			 * As a result, if we go beyond the range we really
+			 * need and hit an delalloc extent boundary followed by
+			 * a hole while we have excess blocks in the map, we
+			 * will fill the hole incorrectly and overrun the
+			 * transaction reservation.
+			 *
+			 * Using a single map prevents this as we are forced to
+			 * check each map we look for overlap with the desired
+			 * range and abort as soon as we find it. Also, given
+			 * that we only return a single map, having one beyond
+			 * what we can return is probably a bit silly.
+			 *
+			 * We also need to check that we don't go beyond EOF;
+			 * this is a truncate optimisation as a truncate sets
+			 * the new file size before block on the pages we
+			 * currently have locked under writeback. Because they
+			 * are about to be tossed, we don't need to write them
+			 * back....
+			 */
+			nimaps = 1;
+			end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
+			error = xfs_bmap_last_offset(NULL, ip, &last_block,
+							XFS_DATA_FORK);
+			if (error)
+				goto trans_cancel;
+
+			last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
+			if ((map_start_fsb + count_fsb) > last_block) {
+				count_fsb = last_block - map_start_fsb;
+				if (count_fsb == 0) {
+					error = EAGAIN;
+					goto trans_cancel;
+				}
+			}
+
+			/*
+			 * From this point onwards we overwrite the imap
+			 * pointer that the caller gave to us.
+			 */
+			error = xfs_bmapi_write(tp, ip, map_start_fsb,
+						count_fsb, 0, &first_block, 1,
+						imap, &nimaps, &free_list);
+			if (error)
+				goto trans_cancel;
+
+			error = xfs_bmap_finish(&tp, &free_list, &committed);
+			if (error)
+				goto trans_cancel;
+
+			error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
+			if (error)
+				goto error0;
+
+			xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		}
+
+		/*
+		 * See if we were able to allocate an extent that
+		 * covers at least part of the callers request
+		 */
+		if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
+			return xfs_alert_fsblock_zero(ip, imap);
+
+		if ((offset_fsb >= imap->br_startoff) &&
+		    (offset_fsb < (imap->br_startoff +
+				   imap->br_blockcount))) {
+			XFS_STATS_INC(xs_xstrat_quick);
+			return 0;
+		}
+
+		/*
+		 * So far we have not mapped the requested part of the
+		 * file, just surrounding data, try again.
+		 */
+		count_fsb -= imap->br_blockcount;
+		map_start_fsb = imap->br_startoff + imap->br_blockcount;
+	}
+
+trans_cancel:
+	xfs_bmap_cancel(&free_list);
+	xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
+error0:
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return XFS_ERROR(error);
+}
+
+int
+xfs_iomap_write_unwritten(
+	xfs_inode_t	*ip,
+	xfs_off_t	offset,
+	size_t		count)
+{
+	xfs_mount_t	*mp = ip->i_mount;
+	xfs_fileoff_t	offset_fsb;
+	xfs_filblks_t	count_fsb;
+	xfs_filblks_t	numblks_fsb;
+	xfs_fsblock_t	firstfsb;
+	int		nimaps;
+	xfs_trans_t	*tp;
+	xfs_bmbt_irec_t imap;
+	xfs_bmap_free_t free_list;
+	xfs_fsize_t	i_size;
+	uint		resblks;
+	int		committed;
+	int		error;
+
+	trace_xfs_unwritten_convert(ip, offset, count);
+
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
+	count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
+
+	/*
+	 * Reserve enough blocks in this transaction for two complete extent
+	 * btree splits.  We may be converting the middle part of an unwritten
+	 * extent and in this case we will insert two new extents in the btree
+	 * each of which could cause a full split.
+	 *
+	 * This reservation amount will be used in the first call to
+	 * xfs_bmbt_split() to select an AG with enough space to satisfy the
+	 * rest of the operation.
+	 */
+	resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
+
+	do {
+		/*
+		 * set up a transaction to convert the range of extents
+		 * from unwritten to real. Do allocations in a loop until
+		 * we have covered the range passed in.
+		 *
+		 * Note that we open code the transaction allocation here
+		 * to pass KM_NOFS--we can't risk to recursing back into
+		 * the filesystem here as we might be asked to write out
+		 * the same inode that we complete here and might deadlock
+		 * on the iolock.
+		 */
+		xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
+		tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
+		tp->t_flags |= XFS_TRANS_RESERVE;
+		error = xfs_trans_reserve(tp, resblks,
+				XFS_WRITE_LOG_RES(mp), 0,
+				XFS_TRANS_PERM_LOG_RES,
+				XFS_WRITE_LOG_COUNT);
+		if (error) {
+			xfs_trans_cancel(tp, 0);
+			return XFS_ERROR(error);
+		}
+
+		xfs_ilock(ip, XFS_ILOCK_EXCL);
+		xfs_trans_ijoin(tp, ip, 0);
+
+		/*
+		 * Modify the unwritten extent state of the buffer.
+		 */
+		xfs_bmap_init(&free_list, &firstfsb);
+		nimaps = 1;
+		error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
+				  XFS_BMAPI_CONVERT, &firstfsb,
+				  1, &imap, &nimaps, &free_list);
+		if (error)
+			goto error_on_bmapi_transaction;
+
+		/*
+		 * Log the updated inode size as we go.  We have to be careful
+		 * to only log it up to the actual write offset if it is
+		 * halfway into a block.
+		 */
+		i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
+		if (i_size > offset + count)
+			i_size = offset + count;
+
+		i_size = xfs_new_eof(ip, i_size);
+		if (i_size) {
+			ip->i_d.di_size = i_size;
+			xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+		}
+
+		error = xfs_bmap_finish(&tp, &free_list, &committed);
+		if (error)
+			goto error_on_bmapi_transaction;
+
+		error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
+		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		if (error)
+			return XFS_ERROR(error);
+
+		if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
+			return xfs_alert_fsblock_zero(ip, &imap);
+
+		if ((numblks_fsb = imap.br_blockcount) == 0) {
+			/*
+			 * The numblks_fsb value should always get
+			 * smaller, otherwise the loop is stuck.
+			 */
+			ASSERT(imap.br_blockcount);
+			break;
+		}
+		offset_fsb += numblks_fsb;
+		count_fsb -= numblks_fsb;
+	} while (count_fsb > 0);
+
+	return 0;
+
+error_on_bmapi_transaction:
+	xfs_bmap_cancel(&free_list);
+	xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT));
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return XFS_ERROR(error);
+}