xfs_iomap.c 19.7 KB
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/*
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 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
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 * All Rights Reserved.
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 *
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 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
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 * published by the Free Software Foundation.
 *
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 * 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.
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 *
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 * 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
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 */
#include "xfs.h"
#include "xfs_fs.h"
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#include "xfs_bit.h"
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#include "xfs_log.h"
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#include "xfs_inum.h"
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#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"
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#include "xfs_alloc_btree.h"
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#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
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#include "xfs_inode_item.h"
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#include "xfs_btree.h"
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#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"
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#include "xfs_trace.h"
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#define XFS_WRITEIO_ALIGN(mp,off)	(((off) >> mp->m_writeio_log) \
						<< mp->m_writeio_log)
#define XFS_WRITE_IMAPS		XFS_BMAP_MAX_NMAP

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STATIC int
xfs_iomap_eof_align_last_fsb(
	xfs_mount_t	*mp,
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	xfs_inode_t	*ip,
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	xfs_extlen_t	extsize,
	xfs_fileoff_t	*last_fsb)
{
	xfs_fileoff_t	new_last_fsb = 0;
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	xfs_extlen_t	align = 0;
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	int		eof, error;

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	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;

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		if (align && XFS_ISIZE(ip) >= XFS_FSB_TO_B(mp, align))
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			new_last_fsb = roundup_64(*last_fsb, align);
	}
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	/*
	 * 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) {
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		error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
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		if (error)
			return error;
		if (eof)
			*last_fsb = new_last_fsb;
	}
	return 0;
}

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STATIC int
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xfs_alert_fsblock_zero(
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	xfs_inode_t	*ip,
	xfs_bmbt_irec_t	*imap)
{
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	xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
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			"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;
}

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int
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xfs_iomap_write_direct(
	xfs_inode_t	*ip,
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	xfs_off_t	offset,
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	size_t		count,
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	xfs_bmbt_irec_t *imap,
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	int		nmaps)
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{
	xfs_mount_t	*mp = ip->i_mount;
	xfs_fileoff_t	offset_fsb;
	xfs_fileoff_t	last_fsb;
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	xfs_filblks_t	count_fsb, resaligned;
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	xfs_fsblock_t	firstfsb;
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	xfs_extlen_t	extsz, temp;
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	int		nimaps;
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	int		bmapi_flag;
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	int		quota_flag;
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	int		rt;
	xfs_trans_t	*tp;
	xfs_bmap_free_t free_list;
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	uint		qblocks, resblks, resrtextents;
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	int		committed;
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	int		error;
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	error = xfs_qm_dqattach(ip, 0);
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	if (error)
		return XFS_ERROR(error);

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	rt = XFS_IS_REALTIME_INODE(ip);
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	extsz = xfs_get_extsz_hint(ip);
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	offset_fsb = XFS_B_TO_FSBT(mp, offset);
	last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
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	if ((offset + count) > XFS_ISIZE(ip)) {
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		error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
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		if (error)
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			return XFS_ERROR(error);
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	} else {
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		if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
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			last_fsb = MIN(last_fsb, (xfs_fileoff_t)
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					imap->br_blockcount +
					imap->br_startoff);
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	}
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	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;
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		resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
		quota_flag = XFS_QMOPT_RES_RTBLKS;
	} else {
		resrtextents = 0;
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		resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
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		quota_flag = XFS_QMOPT_RES_REGBLKS;
	}
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	/*
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	 * Allocate and setup the transaction
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	 */
	tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
	error = xfs_trans_reserve(tp, resblks,
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			XFS_WRITE_LOG_RES(mp), resrtextents,
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			XFS_TRANS_PERM_LOG_RES,
			XFS_WRITE_LOG_COUNT);
	/*
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	 * Check for running out of space, note: need lock to return
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	 */
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	if (error) {
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		xfs_trans_cancel(tp, 0);
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		return XFS_ERROR(error);
	}

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	xfs_ilock(ip, XFS_ILOCK_EXCL);

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	error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
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	if (error)
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		goto out_trans_cancel;
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	xfs_trans_ijoin(tp, ip, 0);
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	bmapi_flag = 0;
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	if (offset < XFS_ISIZE(ip) || extsz)
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		bmapi_flag |= XFS_BMAPI_PREALLOC;

	/*
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	 * From this point onwards we overwrite the imap pointer that the
	 * caller gave to us.
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	 */
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	xfs_bmap_init(&free_list, &firstfsb);
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	nimaps = 1;
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	error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flag,
				&firstfsb, 0, imap, &nimaps, &free_list);
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	if (error)
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		goto out_bmap_cancel;
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	/*
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	 * Complete the transaction
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	 */
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	error = xfs_bmap_finish(&tp, &free_list, &committed);
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	if (error)
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		goto out_bmap_cancel;
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	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
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	if (error)
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		goto out_unlock;
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	/*
	 * Copy any maps to caller's array and return any error.
	 */
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	if (nimaps == 0) {
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		error = XFS_ERROR(ENOSPC);
		goto out_unlock;
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	}

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	if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
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		error = xfs_alert_fsblock_zero(ip, imap);
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out_unlock:
	xfs_iunlock(ip, XFS_ILOCK_EXCL);
	return error;
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out_bmap_cancel:
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	xfs_bmap_cancel(&free_list);
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	xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
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out_trans_cancel:
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	xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
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	goto out_unlock;
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}

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/*
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 * 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().
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 *
 * If we find we already have delalloc preallocation beyond EOF, don't do more
 * preallocation as it it not needed.
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 */
STATIC int
xfs_iomap_eof_want_preallocate(
	xfs_mount_t	*mp,
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	xfs_inode_t	*ip,
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	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;
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	int		found_delalloc = 0;
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	*prealloc = 0;
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	if (offset + count <= XFS_ISIZE(ip))
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		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;
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		firstblock = NULLFSBLOCK;
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		error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
				       0);
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		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;
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			if (imap[n].br_startblock == DELAYSTARTBLOCK)
				found_delalloc = 1;
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		}
	}
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	if (!found_delalloc)
		*prealloc = 1;
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	return 0;
}

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/*
 * 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;

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		/*
		 * 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.
		 */
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		alloc_blocks = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)) + 1;
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		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;
}

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int
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xfs_iomap_write_delay(
	xfs_inode_t	*ip,
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	xfs_off_t	offset,
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	size_t		count,
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	xfs_bmbt_irec_t *ret_imap)
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{
	xfs_mount_t	*mp = ip->i_mount;
	xfs_fileoff_t	offset_fsb;
	xfs_fileoff_t	last_fsb;
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	xfs_off_t	aligned_offset;
	xfs_fileoff_t	ioalign;
	xfs_extlen_t	extsz;
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	int		nimaps;
	xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
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	int		prealloc, flushed = 0;
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	int		error;
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	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
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	/*
	 * Make sure that the dquots are there. This doesn't hold
	 * the ilock across a disk read.
	 */
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	error = xfs_qm_dqattach_locked(ip, 0);
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	if (error)
		return XFS_ERROR(error);

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	extsz = xfs_get_extsz_hint(ip);
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	offset_fsb = XFS_B_TO_FSBT(mp, offset);

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	error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
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				imap, XFS_WRITE_IMAPS, &prealloc);
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	if (error)
		return error;
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retry:
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	if (prealloc) {
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		xfs_fsblock_t	alloc_blocks = xfs_iomap_prealloc_size(mp, ip);

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		aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
		ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
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		last_fsb = ioalign + alloc_blocks;
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	} else {
		last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
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	}

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	if (prealloc || extsz) {
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		error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
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		if (error)
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			return error;
	}
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	/*
	 * Make sure preallocation does not create extents beyond the range we
	 * actually support in this filesystem.
	 */
	if (last_fsb > XFS_B_TO_FSB(mp, mp->m_maxioffset))
		last_fsb = XFS_B_TO_FSB(mp, mp->m_maxioffset);

	ASSERT(last_fsb > offset_fsb);

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	nimaps = XFS_WRITE_IMAPS;
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	error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
				imap, &nimaps, XFS_BMAPI_ENTIRE);
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	switch (error) {
	case 0:
	case ENOSPC:
	case EDQUOT:
		break;
	default:
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		return XFS_ERROR(error);
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	}
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	/*
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	 * 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.
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	 */
	if (nimaps == 0) {
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		trace_xfs_delalloc_enospc(ip, offset, count);
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		if (flushed)
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			return XFS_ERROR(error ? error : ENOSPC);
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		if (error == ENOSPC) {
			xfs_iunlock(ip, XFS_ILOCK_EXCL);
			xfs_flush_inodes(ip);
			xfs_ilock(ip, XFS_ILOCK_EXCL);
		}
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		flushed = 1;
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		error = 0;
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		prealloc = 0;
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		goto retry;
	}

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	if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
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		return xfs_alert_fsblock_zero(ip, &imap[0]);
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	*ret_imap = imap[0];
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	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.
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 *
 * We no longer bother to look at the incoming map - all we have to
 * guarantee is that whatever we allocate fills the required range.
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 */
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int
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xfs_iomap_write_allocate(
	xfs_inode_t	*ip,
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	xfs_off_t	offset,
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	size_t		count,
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	xfs_bmbt_irec_t *imap)
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{
	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;
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	int		nimaps, committed;
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	int		error = 0;
	int		nres;

	/*
	 * Make sure that the dquots are there.
	 */
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	error = xfs_qm_dqattach(ip, 0);
	if (error)
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		return XFS_ERROR(error);

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	offset_fsb = XFS_B_TO_FSBT(mp, offset);
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	count_fsb = imap->br_blockcount;
	map_start_fsb = imap->br_startoff;
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	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);
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			tp->t_flags |= XFS_TRANS_RESERVE;
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			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);
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			xfs_trans_ijoin(tp, ip, 0);
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			xfs_bmap_init(&free_list, &first_block);
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			/*
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			 * 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....
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			 */
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			nimaps = 1;
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			end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
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			error = xfs_bmap_last_offset(NULL, ip, &last_block,
							XFS_DATA_FORK);
			if (error)
				goto trans_cancel;

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			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;
				}
			}

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			/*
			 * From this point onwards we overwrite the imap
			 * pointer that the caller gave to us.
			 */
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			error = xfs_bmapi_write(tp, ip, map_start_fsb,
						count_fsb, 0, &first_block, 1,
						imap, &nimaps, &free_list);
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			if (error)
				goto trans_cancel;

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			error = xfs_bmap_finish(&tp, &free_list, &committed);
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			if (error)
				goto trans_cancel;

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			error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
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			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
		 */
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		if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
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			return xfs_alert_fsblock_zero(ip, imap);
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		if ((offset_fsb >= imap->br_startoff) &&
		    (offset_fsb < (imap->br_startoff +
				   imap->br_blockcount))) {
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			XFS_STATS_INC(xs_xstrat_quick);
			return 0;
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		}

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		/*
		 * So far we have not mapped the requested part of the
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		 * file, just surrounding data, try again.
		 */
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		count_fsb -= imap->br_blockcount;
		map_start_fsb = imap->br_startoff + imap->br_blockcount;
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	}

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,
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	xfs_off_t	offset,
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	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;
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	xfs_fsblock_t	firstfsb;
	int		nimaps;
	xfs_trans_t	*tp;
	xfs_bmbt_irec_t imap;
	xfs_bmap_free_t free_list;
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	xfs_fsize_t	i_size;
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	uint		resblks;
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	int		committed;
	int		error;

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	trace_xfs_unwritten_convert(ip, offset, count);
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	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);

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	/*
	 * 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.
	 */
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	resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
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	do {
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		/*
		 * 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.
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		 *
		 * 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.
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		 */
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		xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
		tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
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		tp->t_flags |= XFS_TRANS_RESERVE;
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		error = xfs_trans_reserve(tp, resblks,
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				XFS_WRITE_LOG_RES(mp), 0,
				XFS_TRANS_PERM_LOG_RES,
				XFS_WRITE_LOG_COUNT);
		if (error) {
			xfs_trans_cancel(tp, 0);
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			return XFS_ERROR(error);
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		}

		xfs_ilock(ip, XFS_ILOCK_EXCL);
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		xfs_trans_ijoin(tp, ip, 0);
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		/*
		 * Modify the unwritten extent state of the buffer.
		 */
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		xfs_bmap_init(&free_list, &firstfsb);
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		nimaps = 1;
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		error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
				  XFS_BMAPI_CONVERT, &firstfsb,
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				  1, &imap, &nimaps, &free_list);
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		if (error)
			goto error_on_bmapi_transaction;

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		/*
		 * 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);
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		if (error)
			goto error_on_bmapi_transaction;

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		error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
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		xfs_iunlock(ip, XFS_ILOCK_EXCL);
		if (error)
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			return XFS_ERROR(error);

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		if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
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			return xfs_alert_fsblock_zero(ip, &imap);
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		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);
}