xfs_iomap.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   4 * Copyright (c) 2016-2018 Christoph Hellwig.
   5 * All Rights Reserved.
   6 */
   7#include "xfs.h"
   8#include "xfs_fs.h"
   9#include "xfs_shared.h"
  10#include "xfs_format.h"
  11#include "xfs_log_format.h"
  12#include "xfs_trans_resv.h"
  13#include "xfs_mount.h"
  14#include "xfs_inode.h"
  15#include "xfs_btree.h"
  16#include "xfs_bmap_btree.h"
  17#include "xfs_bmap.h"
  18#include "xfs_bmap_util.h"
  19#include "xfs_errortag.h"
  20#include "xfs_error.h"
  21#include "xfs_trans.h"
  22#include "xfs_trans_space.h"
  23#include "xfs_inode_item.h"
  24#include "xfs_iomap.h"
  25#include "xfs_trace.h"
  26#include "xfs_quota.h"
  27#include "xfs_rtgroup.h"
  28#include "xfs_dquot_item.h"
  29#include "xfs_dquot.h"
  30#include "xfs_reflink.h"
  31#include "xfs_health.h"
  32#include "xfs_rtbitmap.h"
  33#include "xfs_icache.h"
  34#include "xfs_zone_alloc.h"
  35
  36#define XFS_ALLOC_ALIGN(mp, off) \
  37	(((off) >> mp->m_allocsize_log) << mp->m_allocsize_log)
  38
  39static int
  40xfs_alert_fsblock_zero(
  41	xfs_inode_t	*ip,
  42	xfs_bmbt_irec_t	*imap)
  43{
  44	xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
  45			"Access to block zero in inode %llu "
  46			"start_block: %llx start_off: %llx "
  47			"blkcnt: %llx extent-state: %x",
  48		(unsigned long long)ip->i_ino,
  49		(unsigned long long)imap->br_startblock,
  50		(unsigned long long)imap->br_startoff,
  51		(unsigned long long)imap->br_blockcount,
  52		imap->br_state);
  53	xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
  54	return -EFSCORRUPTED;
  55}
  56
  57u64
  58xfs_iomap_inode_sequence(
  59	struct xfs_inode	*ip,
  60	u16			iomap_flags)
  61{
  62	u64			cookie = 0;
  63
  64	if (iomap_flags & IOMAP_F_XATTR)
  65		return READ_ONCE(ip->i_af.if_seq);
  66	if ((iomap_flags & IOMAP_F_SHARED) && ip->i_cowfp)
  67		cookie = (u64)READ_ONCE(ip->i_cowfp->if_seq) << 32;
  68	return cookie | READ_ONCE(ip->i_df.if_seq);
  69}
  70
  71/*
  72 * Check that the iomap passed to us is still valid for the given offset and
  73 * length.
  74 */
  75static bool
  76xfs_iomap_valid(
  77	struct inode		*inode,
  78	const struct iomap	*iomap)
  79{
  80	struct xfs_inode	*ip = XFS_I(inode);
  81
  82	if (iomap->type == IOMAP_HOLE)
  83		return true;
  84
  85	if (iomap->validity_cookie !=
  86			xfs_iomap_inode_sequence(ip, iomap->flags)) {
  87		trace_xfs_iomap_invalid(ip, iomap);
  88		return false;
  89	}
  90
  91	XFS_ERRORTAG_DELAY(ip->i_mount, XFS_ERRTAG_WRITE_DELAY_MS);
  92	return true;
  93}
  94
  95const struct iomap_write_ops xfs_iomap_write_ops = {
  96	.iomap_valid		= xfs_iomap_valid,
  97};
  98
  99int
 100xfs_bmbt_to_iomap(
 101	struct xfs_inode	*ip,
 102	struct iomap		*iomap,
 103	struct xfs_bmbt_irec	*imap,
 104	unsigned int		mapping_flags,
 105	u16			iomap_flags,
 106	u64			sequence_cookie)
 107{
 108	struct xfs_mount	*mp = ip->i_mount;
 109	struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
 110
 111	if (unlikely(!xfs_valid_startblock(ip, imap->br_startblock))) {
 112		xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
 113		return xfs_alert_fsblock_zero(ip, imap);
 114	}
 115
 116	if (imap->br_startblock == HOLESTARTBLOCK) {
 117		iomap->addr = IOMAP_NULL_ADDR;
 118		iomap->type = IOMAP_HOLE;
 119	} else if (imap->br_startblock == DELAYSTARTBLOCK ||
 120		   isnullstartblock(imap->br_startblock)) {
 121		iomap->addr = IOMAP_NULL_ADDR;
 122		iomap->type = IOMAP_DELALLOC;
 123	} else {
 124		xfs_daddr_t	daddr = xfs_fsb_to_db(ip, imap->br_startblock);
 125
 126		iomap->addr = BBTOB(daddr);
 127		if (mapping_flags & IOMAP_DAX)
 128			iomap->addr += target->bt_dax_part_off;
 129
 130		if (imap->br_state == XFS_EXT_UNWRITTEN)
 131			iomap->type = IOMAP_UNWRITTEN;
 132		else
 133			iomap->type = IOMAP_MAPPED;
 134
 135		/*
 136		 * Mark iomaps starting at the first sector of a RTG as merge
 137		 * boundary so that each I/O completions is contained to a
 138		 * single RTG.
 139		 */
 140		if (XFS_IS_REALTIME_INODE(ip) && xfs_has_rtgroups(mp) &&
 141		    xfs_rtbno_is_group_start(mp, imap->br_startblock))
 142			iomap->flags |= IOMAP_F_BOUNDARY;
 143	}
 144	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
 145	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
 146	if (mapping_flags & IOMAP_DAX)
 147		iomap->dax_dev = target->bt_daxdev;
 148	else
 149		iomap->bdev = target->bt_bdev;
 150	iomap->flags = iomap_flags;
 151
 152	/*
 153	 * If the inode is dirty for datasync purposes, let iomap know so it
 154	 * doesn't elide the IO completion journal flushes on O_DSYNC IO.
 155	 */
 156	if (ip->i_itemp) {
 157		struct xfs_inode_log_item *iip = ip->i_itemp;
 158
 159		spin_lock(&iip->ili_lock);
 160		if (iip->ili_datasync_seq)
 161			iomap->flags |= IOMAP_F_DIRTY;
 162		spin_unlock(&iip->ili_lock);
 163	}
 164
 165	iomap->validity_cookie = sequence_cookie;
 166	return 0;
 167}
 168
 169static void
 170xfs_hole_to_iomap(
 171	struct xfs_inode	*ip,
 172	struct iomap		*iomap,
 173	xfs_fileoff_t		offset_fsb,
 174	xfs_fileoff_t		end_fsb)
 175{
 176	struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
 177
 178	iomap->addr = IOMAP_NULL_ADDR;
 179	iomap->type = IOMAP_HOLE;
 180	iomap->offset = XFS_FSB_TO_B(ip->i_mount, offset_fsb);
 181	iomap->length = XFS_FSB_TO_B(ip->i_mount, end_fsb - offset_fsb);
 182	iomap->bdev = target->bt_bdev;
 183	iomap->dax_dev = target->bt_daxdev;
 184}
 185
 186static inline xfs_fileoff_t
 187xfs_iomap_end_fsb(
 188	struct xfs_mount	*mp,
 189	loff_t			offset,
 190	loff_t			count)
 191{
 192	ASSERT(offset <= mp->m_super->s_maxbytes);
 193	return min(XFS_B_TO_FSB(mp, offset + count),
 194		   XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes));
 195}
 196
 197static xfs_extlen_t
 198xfs_eof_alignment(
 199	struct xfs_inode	*ip)
 200{
 201	struct xfs_mount	*mp = ip->i_mount;
 202	xfs_extlen_t		align = 0;
 203
 204	if (!XFS_IS_REALTIME_INODE(ip)) {
 205		/*
 206		 * Round up the allocation request to a stripe unit
 207		 * (m_dalign) boundary if the file size is >= stripe unit
 208		 * size, and we are allocating past the allocation eof.
 209		 *
 210		 * If mounted with the "-o swalloc" option the alignment is
 211		 * increased from the strip unit size to the stripe width.
 212		 */
 213		if (mp->m_swidth && xfs_has_swalloc(mp))
 214			align = mp->m_swidth;
 215		else if (mp->m_dalign)
 216			align = mp->m_dalign;
 217
 218		if (align && XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, align))
 219			align = 0;
 220	}
 221
 222	return align;
 223}
 224
 225/*
 226 * Check if last_fsb is outside the last extent, and if so grow it to the next
 227 * stripe unit boundary.
 228 */
 229xfs_fileoff_t
 230xfs_iomap_eof_align_last_fsb(
 231	struct xfs_inode	*ip,
 232	xfs_fileoff_t		end_fsb)
 233{
 234	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
 235	xfs_extlen_t		extsz = xfs_get_extsz_hint(ip);
 236	xfs_extlen_t		align = xfs_eof_alignment(ip);
 237	struct xfs_bmbt_irec	irec;
 238	struct xfs_iext_cursor	icur;
 239
 240	ASSERT(!xfs_need_iread_extents(ifp));
 241
 242	/*
 243	 * Always round up the allocation request to the extent hint boundary.
 244	 */
 245	if (extsz) {
 246		if (align)
 247			align = roundup_64(align, extsz);
 248		else
 249			align = extsz;
 250	}
 251
 252	if (align) {
 253		xfs_fileoff_t	aligned_end_fsb = roundup_64(end_fsb, align);
 254
 255		xfs_iext_last(ifp, &icur);
 256		if (!xfs_iext_get_extent(ifp, &icur, &irec) ||
 257		    aligned_end_fsb >= irec.br_startoff + irec.br_blockcount)
 258			return aligned_end_fsb;
 259	}
 260
 261	return end_fsb;
 262}
 263
 264int
 265xfs_iomap_write_direct(
 266	struct xfs_inode	*ip,
 267	xfs_fileoff_t		offset_fsb,
 268	xfs_fileoff_t		count_fsb,
 269	unsigned int		flags,
 270	struct xfs_bmbt_irec	*imap,
 271	u64			*seq)
 272{
 273	struct xfs_mount	*mp = ip->i_mount;
 274	struct xfs_trans	*tp;
 275	xfs_filblks_t		resaligned;
 276	int			nimaps;
 277	unsigned int		dblocks, rblocks;
 278	bool			force = false;
 279	int			error;
 280	int			bmapi_flags = XFS_BMAPI_PREALLOC;
 281	int			nr_exts = XFS_IEXT_ADD_NOSPLIT_CNT;
 282
 283	ASSERT(count_fsb > 0);
 284
 285	resaligned = xfs_aligned_fsb_count(offset_fsb, count_fsb,
 286					   xfs_get_extsz_hint(ip));
 287	if (unlikely(XFS_IS_REALTIME_INODE(ip))) {
 288		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
 289		rblocks = resaligned;
 290	} else {
 291		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 292		rblocks = 0;
 293	}
 294
 295	error = xfs_qm_dqattach(ip);
 296	if (error)
 297		return error;
 298
 299	/*
 300	 * For DAX, we do not allocate unwritten extents, but instead we zero
 301	 * the block before we commit the transaction.  Ideally we'd like to do
 302	 * this outside the transaction context, but if we commit and then crash
 303	 * we may not have zeroed the blocks and this will be exposed on
 304	 * recovery of the allocation. Hence we must zero before commit.
 305	 *
 306	 * Further, if we are mapping unwritten extents here, we need to zero
 307	 * and convert them to written so that we don't need an unwritten extent
 308	 * callback for DAX. This also means that we need to be able to dip into
 309	 * the reserve block pool for bmbt block allocation if there is no space
 310	 * left but we need to do unwritten extent conversion.
 311	 */
 312	if (flags & IOMAP_DAX) {
 313		bmapi_flags = XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO;
 314		if (imap->br_state == XFS_EXT_UNWRITTEN) {
 315			force = true;
 316			nr_exts = XFS_IEXT_WRITE_UNWRITTEN_CNT;
 317			dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 318		}
 319	}
 320
 321	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, dblocks,
 322			rblocks, force, &tp);
 323	if (error)
 324		return error;
 325
 326	error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK, nr_exts);
 327	if (error)
 328		goto out_trans_cancel;
 329
 330	/*
 331	 * From this point onwards we overwrite the imap pointer that the
 332	 * caller gave to us.
 333	 */
 334	nimaps = 1;
 335	error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flags, 0,
 336				imap, &nimaps);
 337	if (error)
 338		goto out_trans_cancel;
 339
 340	/*
 341	 * Complete the transaction
 342	 */
 343	error = xfs_trans_commit(tp);
 344	if (error)
 345		goto out_unlock;
 346
 347	if (unlikely(!xfs_valid_startblock(ip, imap->br_startblock))) {
 348		xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
 349		error = xfs_alert_fsblock_zero(ip, imap);
 350	}
 351
 352out_unlock:
 353	*seq = xfs_iomap_inode_sequence(ip, 0);
 354	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 355	return error;
 356
 357out_trans_cancel:
 358	xfs_trans_cancel(tp);
 359	goto out_unlock;
 360}
 361
 362STATIC bool
 363xfs_quota_need_throttle(
 364	struct xfs_inode	*ip,
 365	xfs_dqtype_t		type,
 366	xfs_fsblock_t		alloc_blocks)
 367{
 368	struct xfs_dquot	*dq = xfs_inode_dquot(ip, type);
 369	struct xfs_dquot_res	*res;
 370	struct xfs_dquot_pre	*pre;
 371
 372	if (!dq || !xfs_this_quota_on(ip->i_mount, type))
 373		return false;
 374
 375	if (XFS_IS_REALTIME_INODE(ip)) {
 376		res = &dq->q_rtb;
 377		pre = &dq->q_rtb_prealloc;
 378	} else {
 379		res = &dq->q_blk;
 380		pre = &dq->q_blk_prealloc;
 381	}
 382
 383	/* no hi watermark, no throttle */
 384	if (!pre->q_prealloc_hi_wmark)
 385		return false;
 386
 387	/* under the lo watermark, no throttle */
 388	if (res->reserved + alloc_blocks < pre->q_prealloc_lo_wmark)
 389		return false;
 390
 391	return true;
 392}
 393
 394STATIC void
 395xfs_quota_calc_throttle(
 396	struct xfs_inode	*ip,
 397	xfs_dqtype_t		type,
 398	xfs_fsblock_t		*qblocks,
 399	int			*qshift,
 400	int64_t			*qfreesp)
 401{
 402	struct xfs_dquot	*dq = xfs_inode_dquot(ip, type);
 403	struct xfs_dquot_res	*res;
 404	struct xfs_dquot_pre	*pre;
 405	int64_t			freesp;
 406	int			shift = 0;
 407
 408	if (!dq) {
 409		res = NULL;
 410		pre = NULL;
 411	} else if (XFS_IS_REALTIME_INODE(ip)) {
 412		res = &dq->q_rtb;
 413		pre = &dq->q_rtb_prealloc;
 414	} else {
 415		res = &dq->q_blk;
 416		pre = &dq->q_blk_prealloc;
 417	}
 418
 419	/* no dq, or over hi wmark, squash the prealloc completely */
 420	if (!res || res->reserved >= pre->q_prealloc_hi_wmark) {
 421		*qblocks = 0;
 422		*qfreesp = 0;
 423		return;
 424	}
 425
 426	freesp = pre->q_prealloc_hi_wmark - res->reserved;
 427	if (freesp < pre->q_low_space[XFS_QLOWSP_5_PCNT]) {
 428		shift = 2;
 429		if (freesp < pre->q_low_space[XFS_QLOWSP_3_PCNT])
 430			shift += 2;
 431		if (freesp < pre->q_low_space[XFS_QLOWSP_1_PCNT])
 432			shift += 2;
 433	}
 434
 435	if (freesp < *qfreesp)
 436		*qfreesp = freesp;
 437
 438	/* only overwrite the throttle values if we are more aggressive */
 439	if ((freesp >> shift) < (*qblocks >> *qshift)) {
 440		*qblocks = freesp;
 441		*qshift = shift;
 442	}
 443}
 444
 445static int64_t
 446xfs_iomap_freesp(
 447	struct xfs_mount	*mp,
 448	unsigned int		idx,
 449	uint64_t		low_space[XFS_LOWSP_MAX],
 450	int			*shift)
 451{
 452	int64_t			freesp;
 453
 454	freesp = xfs_estimate_freecounter(mp, idx);
 455	if (freesp < low_space[XFS_LOWSP_5_PCNT]) {
 456		*shift = 2;
 457		if (freesp < low_space[XFS_LOWSP_4_PCNT])
 458			(*shift)++;
 459		if (freesp < low_space[XFS_LOWSP_3_PCNT])
 460			(*shift)++;
 461		if (freesp < low_space[XFS_LOWSP_2_PCNT])
 462			(*shift)++;
 463		if (freesp < low_space[XFS_LOWSP_1_PCNT])
 464			(*shift)++;
 465	}
 466	return freesp;
 467}
 468
 469/*
 470 * If we don't have a user specified preallocation size, dynamically increase
 471 * the preallocation size as the size of the file grows.  Cap the maximum size
 472 * at a single extent or less if the filesystem is near full. The closer the
 473 * filesystem is to being full, the smaller the maximum preallocation.
 474 */
 475STATIC xfs_fsblock_t
 476xfs_iomap_prealloc_size(
 477	struct xfs_inode	*ip,
 478	int			whichfork,
 479	loff_t			offset,
 480	loff_t			count,
 481	struct xfs_iext_cursor	*icur)
 482{
 483	struct xfs_iext_cursor	ncur = *icur;
 484	struct xfs_bmbt_irec	prev, got;
 485	struct xfs_mount	*mp = ip->i_mount;
 486	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 487	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 488	int64_t			freesp;
 489	xfs_fsblock_t		qblocks;
 490	xfs_fsblock_t		alloc_blocks = 0;
 491	xfs_extlen_t		plen;
 492	int			shift = 0;
 493	int			qshift = 0;
 494
 495	/*
 496	 * As an exception we don't do any preallocation at all if the file is
 497	 * smaller than the minimum preallocation and we are using the default
 498	 * dynamic preallocation scheme, as it is likely this is the only write
 499	 * to the file that is going to be done.
 500	 */
 501	if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_allocsize_blocks))
 502		return 0;
 503
 504	/*
 505	 * Use the minimum preallocation size for small files or if we are
 506	 * writing right after a hole.
 507	 */
 508	if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
 509	    !xfs_iext_prev_extent(ifp, &ncur, &prev) ||
 510	    prev.br_startoff + prev.br_blockcount < offset_fsb)
 511		return mp->m_allocsize_blocks;
 512
 513	/*
 514	 * Take the size of the preceding data extents as the basis for the
 515	 * preallocation size. Note that we don't care if the previous extents
 516	 * are written or not.
 517	 */
 518	plen = prev.br_blockcount;
 519	while (xfs_iext_prev_extent(ifp, &ncur, &got)) {
 520		if (plen > XFS_MAX_BMBT_EXTLEN / 2 ||
 521		    isnullstartblock(got.br_startblock) ||
 522		    got.br_startoff + got.br_blockcount != prev.br_startoff ||
 523		    got.br_startblock + got.br_blockcount != prev.br_startblock)
 524			break;
 525		plen += got.br_blockcount;
 526		prev = got;
 527	}
 528
 529	/*
 530	 * If the size of the extents is greater than half the maximum extent
 531	 * length, then use the current offset as the basis.  This ensures that
 532	 * for large files the preallocation size always extends to
 533	 * XFS_BMBT_MAX_EXTLEN rather than falling short due to things like stripe
 534	 * unit/width alignment of real extents.
 535	 */
 536	alloc_blocks = plen * 2;
 537	if (alloc_blocks > XFS_MAX_BMBT_EXTLEN)
 538		alloc_blocks = XFS_B_TO_FSB(mp, offset);
 539	qblocks = alloc_blocks;
 540
 541	/*
 542	 * XFS_BMBT_MAX_EXTLEN is not a power of two value but we round the prealloc
 543	 * down to the nearest power of two value after throttling. To prevent
 544	 * the round down from unconditionally reducing the maximum supported
 545	 * prealloc size, we round up first, apply appropriate throttling, round
 546	 * down and cap the value to XFS_BMBT_MAX_EXTLEN.
 547	 */
 548	alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(XFS_MAX_BMBT_EXTLEN),
 549				       alloc_blocks);
 550
 551	if (unlikely(XFS_IS_REALTIME_INODE(ip)))
 552		freesp = xfs_rtbxlen_to_blen(mp,
 553				xfs_iomap_freesp(mp, XC_FREE_RTEXTENTS,
 554					mp->m_low_rtexts, &shift));
 555	else
 556		freesp = xfs_iomap_freesp(mp, XC_FREE_BLOCKS, mp->m_low_space,
 557				&shift);
 558
 559	/*
 560	 * Check each quota to cap the prealloc size, provide a shift value to
 561	 * throttle with and adjust amount of available space.
 562	 */
 563	if (xfs_quota_need_throttle(ip, XFS_DQTYPE_USER, alloc_blocks))
 564		xfs_quota_calc_throttle(ip, XFS_DQTYPE_USER, &qblocks, &qshift,
 565					&freesp);
 566	if (xfs_quota_need_throttle(ip, XFS_DQTYPE_GROUP, alloc_blocks))
 567		xfs_quota_calc_throttle(ip, XFS_DQTYPE_GROUP, &qblocks, &qshift,
 568					&freesp);
 569	if (xfs_quota_need_throttle(ip, XFS_DQTYPE_PROJ, alloc_blocks))
 570		xfs_quota_calc_throttle(ip, XFS_DQTYPE_PROJ, &qblocks, &qshift,
 571					&freesp);
 572
 573	/*
 574	 * The final prealloc size is set to the minimum of free space available
 575	 * in each of the quotas and the overall filesystem.
 576	 *
 577	 * The shift throttle value is set to the maximum value as determined by
 578	 * the global low free space values and per-quota low free space values.
 579	 */
 580	alloc_blocks = min(alloc_blocks, qblocks);
 581	shift = max(shift, qshift);
 582
 583	if (shift)
 584		alloc_blocks >>= shift;
 585	/*
 586	 * rounddown_pow_of_two() returns an undefined result if we pass in
 587	 * alloc_blocks = 0.
 588	 */
 589	if (alloc_blocks)
 590		alloc_blocks = rounddown_pow_of_two(alloc_blocks);
 591	if (alloc_blocks > XFS_MAX_BMBT_EXTLEN)
 592		alloc_blocks = XFS_MAX_BMBT_EXTLEN;
 593
 594	/*
 595	 * If we are still trying to allocate more space than is
 596	 * available, squash the prealloc hard. This can happen if we
 597	 * have a large file on a small filesystem and the above
 598	 * lowspace thresholds are smaller than XFS_BMBT_MAX_EXTLEN.
 599	 */
 600	while (alloc_blocks && alloc_blocks >= freesp)
 601		alloc_blocks >>= 4;
 602	if (alloc_blocks < mp->m_allocsize_blocks)
 603		alloc_blocks = mp->m_allocsize_blocks;
 604	trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
 605				      mp->m_allocsize_blocks);
 606	return alloc_blocks;
 607}
 608
 609int
 610xfs_iomap_write_unwritten(
 611	xfs_inode_t	*ip,
 612	xfs_off_t	offset,
 613	xfs_off_t	count,
 614	bool		update_isize)
 615{
 616	xfs_mount_t	*mp = ip->i_mount;
 617	xfs_fileoff_t	offset_fsb;
 618	xfs_filblks_t	count_fsb;
 619	xfs_filblks_t	numblks_fsb;
 620	int		nimaps;
 621	xfs_trans_t	*tp;
 622	xfs_bmbt_irec_t imap;
 623	struct inode	*inode = VFS_I(ip);
 624	xfs_fsize_t	i_size;
 625	uint		resblks;
 626	int		error;
 627
 628	trace_xfs_unwritten_convert(ip, offset, count);
 629
 630	offset_fsb = XFS_B_TO_FSBT(mp, offset);
 631	count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 632	count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
 633
 634	/*
 635	 * Reserve enough blocks in this transaction for two complete extent
 636	 * btree splits.  We may be converting the middle part of an unwritten
 637	 * extent and in this case we will insert two new extents in the btree
 638	 * each of which could cause a full split.
 639	 *
 640	 * This reservation amount will be used in the first call to
 641	 * xfs_bmbt_split() to select an AG with enough space to satisfy the
 642	 * rest of the operation.
 643	 */
 644	resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
 645
 646	/* Attach dquots so that bmbt splits are accounted correctly. */
 647	error = xfs_qm_dqattach(ip);
 648	if (error)
 649		return error;
 650
 651	do {
 652		/*
 653		 * Set up a transaction to convert the range of extents
 654		 * from unwritten to real. Do allocations in a loop until
 655		 * we have covered the range passed in.
 656		 *
 657		 * Note that we can't risk to recursing back into the filesystem
 658		 * here as we might be asked to write out the same inode that we
 659		 * complete here and might deadlock on the iolock.
 660		 */
 661		error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks,
 662				0, true, &tp);
 663		if (error)
 664			return error;
 665
 666		error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK,
 667				XFS_IEXT_WRITE_UNWRITTEN_CNT);
 668		if (error)
 669			goto error_on_bmapi_transaction;
 670
 671		/*
 672		 * Modify the unwritten extent state of the buffer.
 673		 */
 674		nimaps = 1;
 675		error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
 676					XFS_BMAPI_CONVERT, resblks, &imap,
 677					&nimaps);
 678		if (error)
 679			goto error_on_bmapi_transaction;
 680
 681		/*
 682		 * Log the updated inode size as we go.  We have to be careful
 683		 * to only log it up to the actual write offset if it is
 684		 * halfway into a block.
 685		 */
 686		i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
 687		if (i_size > offset + count)
 688			i_size = offset + count;
 689		if (update_isize && i_size > i_size_read(inode))
 690			i_size_write(inode, i_size);
 691		i_size = xfs_new_eof(ip, i_size);
 692		if (i_size) {
 693			ip->i_disk_size = i_size;
 694			xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 695		}
 696
 697		error = xfs_trans_commit(tp);
 698		xfs_iunlock(ip, XFS_ILOCK_EXCL);
 699		if (error)
 700			return error;
 701
 702		if (unlikely(!xfs_valid_startblock(ip, imap.br_startblock))) {
 703			xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
 704			return xfs_alert_fsblock_zero(ip, &imap);
 705		}
 706
 707		if ((numblks_fsb = imap.br_blockcount) == 0) {
 708			/*
 709			 * The numblks_fsb value should always get
 710			 * smaller, otherwise the loop is stuck.
 711			 */
 712			ASSERT(imap.br_blockcount);
 713			break;
 714		}
 715		offset_fsb += numblks_fsb;
 716		count_fsb -= numblks_fsb;
 717	} while (count_fsb > 0);
 718
 719	return 0;
 720
 721error_on_bmapi_transaction:
 722	xfs_trans_cancel(tp);
 723	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 724	return error;
 725}
 726
 727static inline bool
 728imap_needs_alloc(
 729	struct inode		*inode,
 730	unsigned		flags,
 731	struct xfs_bmbt_irec	*imap,
 732	int			nimaps)
 733{
 734	/* don't allocate blocks when just zeroing */
 735	if (flags & IOMAP_ZERO)
 736		return false;
 737	if (!nimaps ||
 738	    imap->br_startblock == HOLESTARTBLOCK ||
 739	    imap->br_startblock == DELAYSTARTBLOCK)
 740		return true;
 741	/* we convert unwritten extents before copying the data for DAX */
 742	if ((flags & IOMAP_DAX) && imap->br_state == XFS_EXT_UNWRITTEN)
 743		return true;
 744	return false;
 745}
 746
 747static inline bool
 748imap_needs_cow(
 749	struct xfs_inode	*ip,
 750	unsigned int		flags,
 751	struct xfs_bmbt_irec	*imap,
 752	int			nimaps)
 753{
 754	if (!xfs_is_cow_inode(ip))
 755		return false;
 756
 757	/* when zeroing we don't have to COW holes or unwritten extents */
 758	if (flags & (IOMAP_UNSHARE | IOMAP_ZERO)) {
 759		if (!nimaps ||
 760		    imap->br_startblock == HOLESTARTBLOCK ||
 761		    imap->br_state == XFS_EXT_UNWRITTEN)
 762			return false;
 763	}
 764
 765	return true;
 766}
 767
 768/*
 769 * Extents not yet cached requires exclusive access, don't block for
 770 * IOMAP_NOWAIT.
 771 *
 772 * This is basically an opencoded xfs_ilock_data_map_shared() call, but with
 773 * support for IOMAP_NOWAIT.
 774 */
 775static int
 776xfs_ilock_for_iomap(
 777	struct xfs_inode	*ip,
 778	unsigned		flags,
 779	unsigned		*lockmode)
 780{
 781	if (flags & IOMAP_NOWAIT) {
 782		if (xfs_need_iread_extents(&ip->i_df))
 783			return -EAGAIN;
 784		if (!xfs_ilock_nowait(ip, *lockmode))
 785			return -EAGAIN;
 786	} else {
 787		if (xfs_need_iread_extents(&ip->i_df))
 788			*lockmode = XFS_ILOCK_EXCL;
 789		xfs_ilock(ip, *lockmode);
 790	}
 791
 792	return 0;
 793}
 794
 795/*
 796 * Check that the imap we are going to return to the caller spans the entire
 797 * range that the caller requested for the IO.
 798 */
 799static bool
 800imap_spans_range(
 801	struct xfs_bmbt_irec	*imap,
 802	xfs_fileoff_t		offset_fsb,
 803	xfs_fileoff_t		end_fsb)
 804{
 805	if (imap->br_startoff > offset_fsb)
 806		return false;
 807	if (imap->br_startoff + imap->br_blockcount < end_fsb)
 808		return false;
 809	return true;
 810}
 811
 812static bool
 813xfs_bmap_hw_atomic_write_possible(
 814	struct xfs_inode	*ip,
 815	struct xfs_bmbt_irec	*imap,
 816	xfs_fileoff_t		offset_fsb,
 817	xfs_fileoff_t		end_fsb)
 818{
 819	struct xfs_mount	*mp = ip->i_mount;
 820	xfs_fsize_t		len = XFS_FSB_TO_B(mp, end_fsb - offset_fsb);
 821
 822	/*
 823	 * atomic writes are required to be naturally aligned for disk blocks,
 824	 * which ensures that we adhere to block layer rules that we won't
 825	 * straddle any boundary or violate write alignment requirement.
 826	 */
 827	if (!IS_ALIGNED(imap->br_startblock, imap->br_blockcount))
 828		return false;
 829
 830	/*
 831	 * Spanning multiple extents would mean that multiple BIOs would be
 832	 * issued, and so would lose atomicity required for REQ_ATOMIC-based
 833	 * atomics.
 834	 */
 835	if (!imap_spans_range(imap, offset_fsb, end_fsb))
 836		return false;
 837
 838	/*
 839	 * The ->iomap_begin caller should ensure this, but check anyway.
 840	 */
 841	return len <= xfs_inode_buftarg(ip)->bt_awu_max;
 842}
 843
 844static int
 845xfs_direct_write_iomap_begin(
 846	struct inode		*inode,
 847	loff_t			offset,
 848	loff_t			length,
 849	unsigned		flags,
 850	struct iomap		*iomap,
 851	struct iomap		*srcmap)
 852{
 853	struct xfs_inode	*ip = XFS_I(inode);
 854	struct xfs_mount	*mp = ip->i_mount;
 855	struct xfs_bmbt_irec	imap, cmap;
 856	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 857	xfs_fileoff_t		end_fsb = xfs_iomap_end_fsb(mp, offset, length);
 858	xfs_fileoff_t		orig_end_fsb = end_fsb;
 859	int			nimaps = 1, error = 0;
 860	bool			shared = false;
 861	u16			iomap_flags = 0;
 862	bool			needs_alloc;
 863	unsigned int		lockmode;
 864	u64			seq;
 865
 866	ASSERT(flags & (IOMAP_WRITE | IOMAP_ZERO));
 867
 868	if (xfs_is_shutdown(mp))
 869		return -EIO;
 870
 871	/*
 872	 * Writes that span EOF might trigger an IO size update on completion,
 873	 * so consider them to be dirty for the purposes of O_DSYNC even if
 874	 * there is no other metadata changes pending or have been made here.
 875	 */
 876	if (offset + length > i_size_read(inode))
 877		iomap_flags |= IOMAP_F_DIRTY;
 878
 879	/* HW-offload atomics are always used in this path */
 880	if (flags & IOMAP_ATOMIC)
 881		iomap_flags |= IOMAP_F_ATOMIC_BIO;
 882
 883	/*
 884	 * COW writes may allocate delalloc space or convert unwritten COW
 885	 * extents, so we need to make sure to take the lock exclusively here.
 886	 */
 887	if (xfs_is_cow_inode(ip))
 888		lockmode = XFS_ILOCK_EXCL;
 889	else
 890		lockmode = XFS_ILOCK_SHARED;
 891
 892relock:
 893	error = xfs_ilock_for_iomap(ip, flags, &lockmode);
 894	if (error)
 895		return error;
 896
 897	/*
 898	 * The reflink iflag could have changed since the earlier unlocked
 899	 * check, check if it again and relock if needed.
 900	 */
 901	if (xfs_is_cow_inode(ip) && lockmode == XFS_ILOCK_SHARED) {
 902		xfs_iunlock(ip, lockmode);
 903		lockmode = XFS_ILOCK_EXCL;
 904		goto relock;
 905	}
 906
 907	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
 908			       &nimaps, 0);
 909	if (error)
 910		goto out_unlock;
 911
 912	if (imap_needs_cow(ip, flags, &imap, nimaps)) {
 913		error = -EAGAIN;
 914		if (flags & IOMAP_NOWAIT)
 915			goto out_unlock;
 916
 917		/* may drop and re-acquire the ilock */
 918		error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
 919				&lockmode,
 920				(flags & IOMAP_DIRECT) || IS_DAX(inode));
 921		if (error)
 922			goto out_unlock;
 923		if (shared) {
 924			if ((flags & IOMAP_ATOMIC) &&
 925			    !xfs_bmap_hw_atomic_write_possible(ip, &cmap,
 926					offset_fsb, end_fsb)) {
 927				error = -ENOPROTOOPT;
 928				goto out_unlock;
 929			}
 930			goto out_found_cow;
 931		}
 932		end_fsb = imap.br_startoff + imap.br_blockcount;
 933		length = XFS_FSB_TO_B(mp, end_fsb) - offset;
 934	}
 935
 936	needs_alloc = imap_needs_alloc(inode, flags, &imap, nimaps);
 937
 938	if (flags & IOMAP_ATOMIC) {
 939		error = -ENOPROTOOPT;
 940		/*
 941		 * If we allocate less than what is required for the write
 942		 * then we may end up with multiple extents, which means that
 943		 * REQ_ATOMIC-based cannot be used, so avoid this possibility.
 944		 */
 945		if (needs_alloc && orig_end_fsb - offset_fsb > 1)
 946			goto out_unlock;
 947
 948		if (!xfs_bmap_hw_atomic_write_possible(ip, &imap, offset_fsb,
 949				orig_end_fsb))
 950			goto out_unlock;
 951	}
 952
 953	if (needs_alloc)
 954		goto allocate_blocks;
 955
 956	/*
 957	 * NOWAIT and OVERWRITE I/O needs to span the entire requested I/O with
 958	 * a single map so that we avoid partial IO failures due to the rest of
 959	 * the I/O range not covered by this map triggering an EAGAIN condition
 960	 * when it is subsequently mapped and aborting the I/O.
 961	 */
 962	if (flags & (IOMAP_NOWAIT | IOMAP_OVERWRITE_ONLY)) {
 963		error = -EAGAIN;
 964		if (!imap_spans_range(&imap, offset_fsb, end_fsb))
 965			goto out_unlock;
 966	}
 967
 968	/*
 969	 * For overwrite only I/O, we cannot convert unwritten extents without
 970	 * requiring sub-block zeroing.  This can only be done under an
 971	 * exclusive IOLOCK, hence return -EAGAIN if this is not a written
 972	 * extent to tell the caller to try again.
 973	 */
 974	if (flags & IOMAP_OVERWRITE_ONLY) {
 975		error = -EAGAIN;
 976		if (imap.br_state != XFS_EXT_NORM &&
 977	            ((offset | length) & mp->m_blockmask))
 978			goto out_unlock;
 979	}
 980
 981	seq = xfs_iomap_inode_sequence(ip, iomap_flags);
 982	xfs_iunlock(ip, lockmode);
 983	trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
 984	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags, iomap_flags, seq);
 985
 986allocate_blocks:
 987	error = -EAGAIN;
 988	if (flags & (IOMAP_NOWAIT | IOMAP_OVERWRITE_ONLY))
 989		goto out_unlock;
 990
 991	/*
 992	 * We cap the maximum length we map to a sane size  to keep the chunks
 993	 * of work done where somewhat symmetric with the work writeback does.
 994	 * This is a completely arbitrary number pulled out of thin air as a
 995	 * best guess for initial testing.
 996	 *
 997	 * Note that the values needs to be less than 32-bits wide until the
 998	 * lower level functions are updated.
 999	 */
1000	length = min_t(loff_t, length, 1024 * PAGE_SIZE);
1001	end_fsb = xfs_iomap_end_fsb(mp, offset, length);
1002
1003	if (offset + length > XFS_ISIZE(ip))
1004		end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
1005	else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
1006		end_fsb = min(end_fsb, imap.br_startoff + imap.br_blockcount);
1007	xfs_iunlock(ip, lockmode);
1008
1009	error = xfs_iomap_write_direct(ip, offset_fsb, end_fsb - offset_fsb,
1010			flags, &imap, &seq);
1011	if (error)
1012		return error;
1013
1014	trace_xfs_iomap_alloc(ip, offset, length, XFS_DATA_FORK, &imap);
1015	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags,
1016				 iomap_flags | IOMAP_F_NEW, seq);
1017
1018out_found_cow:
1019	length = XFS_FSB_TO_B(mp, cmap.br_startoff + cmap.br_blockcount);
1020	trace_xfs_iomap_found(ip, offset, length - offset, XFS_COW_FORK, &cmap);
1021	if (imap.br_startblock != HOLESTARTBLOCK) {
1022		seq = xfs_iomap_inode_sequence(ip, 0);
1023		error = xfs_bmbt_to_iomap(ip, srcmap, &imap, flags, 0, seq);
1024		if (error)
1025			goto out_unlock;
1026	}
1027	seq = xfs_iomap_inode_sequence(ip, IOMAP_F_SHARED);
1028	xfs_iunlock(ip, lockmode);
1029	return xfs_bmbt_to_iomap(ip, iomap, &cmap, flags, IOMAP_F_SHARED, seq);
1030
1031out_unlock:
1032	if (lockmode)
1033		xfs_iunlock(ip, lockmode);
1034	return error;
1035}
1036
1037const struct iomap_ops xfs_direct_write_iomap_ops = {
1038	.iomap_begin		= xfs_direct_write_iomap_begin,
1039};
1040
1041#ifdef CONFIG_XFS_RT
1042/*
1043 * This is really simple.  The space has already been reserved before taking the
1044 * IOLOCK, the actual block allocation is done just before submitting the bio
1045 * and only recorded in the extent map on I/O completion.
1046 */
1047static int
1048xfs_zoned_direct_write_iomap_begin(
1049	struct inode		*inode,
1050	loff_t			offset,
1051	loff_t			length,
1052	unsigned		flags,
1053	struct iomap		*iomap,
1054	struct iomap		*srcmap)
1055{
1056	struct xfs_inode	*ip = XFS_I(inode);
1057	int			error;
1058
1059	ASSERT(!(flags & IOMAP_OVERWRITE_ONLY));
1060
1061	/*
1062	 * Needs to be pushed down into the allocator so that only writes into
1063	 * a single zone can be supported.
1064	 */
1065	if (flags & IOMAP_NOWAIT)
1066		return -EAGAIN;
1067
1068	/*
1069	 * Ensure the extent list is in memory in so that we don't have to do
1070	 * read it from the I/O completion handler.
1071	 */
1072	if (xfs_need_iread_extents(&ip->i_df)) {
1073		xfs_ilock(ip, XFS_ILOCK_EXCL);
1074		error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
1075		xfs_iunlock(ip, XFS_ILOCK_EXCL);
1076		if (error)
1077			return error;
1078	}
1079
1080	iomap->type = IOMAP_MAPPED;
1081	iomap->flags = IOMAP_F_DIRTY;
1082	iomap->bdev = ip->i_mount->m_rtdev_targp->bt_bdev;
1083	iomap->offset = offset;
1084	iomap->length = length;
1085	iomap->flags = IOMAP_F_ANON_WRITE;
1086	return 0;
1087}
1088
1089const struct iomap_ops xfs_zoned_direct_write_iomap_ops = {
1090	.iomap_begin		= xfs_zoned_direct_write_iomap_begin,
1091};
1092#endif /* CONFIG_XFS_RT */
1093
1094#ifdef DEBUG
1095static void
1096xfs_check_atomic_cow_conversion(
1097	struct xfs_inode		*ip,
1098	xfs_fileoff_t			offset_fsb,
1099	xfs_filblks_t			count_fsb,
1100	const struct xfs_bmbt_irec	*cmap)
1101{
1102	struct xfs_iext_cursor		icur;
1103	struct xfs_bmbt_irec		cmap2 = { };
1104
1105	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &cmap2))
1106		xfs_trim_extent(&cmap2, offset_fsb, count_fsb);
1107
1108	ASSERT(cmap2.br_startoff == cmap->br_startoff);
1109	ASSERT(cmap2.br_blockcount == cmap->br_blockcount);
1110	ASSERT(cmap2.br_startblock == cmap->br_startblock);
1111	ASSERT(cmap2.br_state == cmap->br_state);
1112}
1113#else
1114# define xfs_check_atomic_cow_conversion(...)	((void)0)
1115#endif
1116
1117static int
1118xfs_atomic_write_cow_iomap_begin(
1119	struct inode		*inode,
1120	loff_t			offset,
1121	loff_t			length,
1122	unsigned		flags,
1123	struct iomap		*iomap,
1124	struct iomap		*srcmap)
1125{
1126	struct xfs_inode	*ip = XFS_I(inode);
1127	struct xfs_mount	*mp = ip->i_mount;
1128	const xfs_fileoff_t	offset_fsb = XFS_B_TO_FSBT(mp, offset);
1129	const xfs_fileoff_t	end_fsb = XFS_B_TO_FSB(mp, offset + length);
1130	const xfs_filblks_t	count_fsb = end_fsb - offset_fsb;
1131	xfs_filblks_t		hole_count_fsb;
1132	int			nmaps = 1;
1133	xfs_filblks_t		resaligned;
1134	struct xfs_bmbt_irec	cmap;
1135	struct xfs_iext_cursor	icur;
1136	struct xfs_trans	*tp;
1137	unsigned int		dblocks = 0, rblocks = 0;
1138	int			error;
1139	u64			seq;
1140
1141	ASSERT(flags & IOMAP_WRITE);
1142	ASSERT(flags & IOMAP_DIRECT);
1143
1144	if (xfs_is_shutdown(mp))
1145		return -EIO;
1146
1147	if (!xfs_can_sw_atomic_write(mp)) {
1148		ASSERT(xfs_can_sw_atomic_write(mp));
1149		return -EINVAL;
1150	}
1151
1152	/* blocks are always allocated in this path */
1153	if (flags & IOMAP_NOWAIT)
1154		return -EAGAIN;
1155
1156	trace_xfs_iomap_atomic_write_cow(ip, offset, length);
1157retry:
1158	xfs_ilock(ip, XFS_ILOCK_EXCL);
1159
1160	if (!ip->i_cowfp) {
1161		ASSERT(!xfs_is_reflink_inode(ip));
1162		xfs_ifork_init_cow(ip);
1163	}
1164
1165	if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &cmap))
1166		cmap.br_startoff = end_fsb;
1167	if (cmap.br_startoff <= offset_fsb) {
1168		if (isnullstartblock(cmap.br_startblock))
1169			goto convert_delay;
1170
1171		/*
1172		 * cmap could extend outside the write range due to previous
1173		 * speculative preallocations.  We must trim cmap to the write
1174		 * range because the cow fork treats written mappings to mean
1175		 * "write in progress".
1176		 */
1177		xfs_trim_extent(&cmap, offset_fsb, count_fsb);
1178		goto found;
1179	}
1180
1181	hole_count_fsb = cmap.br_startoff - offset_fsb;
1182
1183	resaligned = xfs_aligned_fsb_count(offset_fsb, hole_count_fsb,
1184			xfs_get_cowextsz_hint(ip));
1185	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1186
1187	if (XFS_IS_REALTIME_INODE(ip)) {
1188		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
1189		rblocks = resaligned;
1190	} else {
1191		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
1192		rblocks = 0;
1193	}
1194
1195	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, dblocks,
1196			rblocks, false, &tp);
1197	if (error)
1198		return error;
1199
1200	/* extent layout could have changed since the unlock, so check again */
1201	if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &cmap))
1202		cmap.br_startoff = end_fsb;
1203	if (cmap.br_startoff <= offset_fsb) {
1204		xfs_trans_cancel(tp);
1205		if (isnullstartblock(cmap.br_startblock))
1206			goto convert_delay;
1207		xfs_trim_extent(&cmap, offset_fsb, count_fsb);
1208		goto found;
1209	}
1210
1211	/*
1212	 * Allocate the entire reservation as unwritten blocks.
1213	 *
1214	 * Use XFS_BMAPI_EXTSZALIGN to hint at aligning new extents according to
1215	 * extszhint, such that there will be a greater chance that future
1216	 * atomic writes to that same range will be aligned (and don't require
1217	 * this COW-based method).
1218	 */
1219	error = xfs_bmapi_write(tp, ip, offset_fsb, hole_count_fsb,
1220			XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC |
1221			XFS_BMAPI_EXTSZALIGN, 0, &cmap, &nmaps);
1222	if (error) {
1223		xfs_trans_cancel(tp);
1224		goto out_unlock;
1225	}
1226
1227	xfs_inode_set_cowblocks_tag(ip);
1228	error = xfs_trans_commit(tp);
1229	if (error)
1230		goto out_unlock;
1231
1232	/*
1233	 * cmap could map more blocks than the range we passed into bmapi_write
1234	 * because of EXTSZALIGN or adjacent pre-existing unwritten mappings
1235	 * that were merged.  Trim cmap to the original write range so that we
1236	 * don't convert more than we were asked to do for this write.
1237	 */
1238	xfs_trim_extent(&cmap, offset_fsb, count_fsb);
1239
1240found:
1241	if (cmap.br_state != XFS_EXT_NORM) {
1242		error = xfs_reflink_convert_cow_locked(ip, cmap.br_startoff,
1243				cmap.br_blockcount);
1244		if (error)
1245			goto out_unlock;
1246		cmap.br_state = XFS_EXT_NORM;
1247		xfs_check_atomic_cow_conversion(ip, offset_fsb, count_fsb,
1248				&cmap);
1249	}
1250
1251	trace_xfs_iomap_found(ip, offset, length, XFS_COW_FORK, &cmap);
1252	seq = xfs_iomap_inode_sequence(ip, IOMAP_F_SHARED);
1253	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1254	return xfs_bmbt_to_iomap(ip, iomap, &cmap, flags, IOMAP_F_SHARED, seq);
1255
1256convert_delay:
1257	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1258	error = xfs_bmapi_convert_delalloc(ip, XFS_COW_FORK, offset, iomap,
1259			NULL);
1260	if (error)
1261		return error;
1262
1263	/*
1264	 * Try the lookup again, because the delalloc conversion might have
1265	 * turned the COW mapping into unwritten, but we need it to be in
1266	 * written state.
1267	 */
1268	goto retry;
1269out_unlock:
1270	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1271	return error;
1272}
1273
1274const struct iomap_ops xfs_atomic_write_cow_iomap_ops = {
1275	.iomap_begin		= xfs_atomic_write_cow_iomap_begin,
1276};
1277
1278static int
1279xfs_dax_write_iomap_end(
1280	struct inode		*inode,
1281	loff_t			pos,
1282	loff_t			length,
1283	ssize_t			written,
1284	unsigned		flags,
1285	struct iomap		*iomap)
1286{
1287	struct xfs_inode	*ip = XFS_I(inode);
1288
1289	if (!xfs_is_cow_inode(ip))
1290		return 0;
1291
1292	if (!written)
1293		return xfs_reflink_cancel_cow_range(ip, pos, length, true);
1294
1295	return xfs_reflink_end_cow(ip, pos, written);
1296}
1297
1298const struct iomap_ops xfs_dax_write_iomap_ops = {
1299	.iomap_begin	= xfs_direct_write_iomap_begin,
1300	.iomap_end	= xfs_dax_write_iomap_end,
1301};
1302
1303/*
1304 * Convert a hole to a delayed allocation.
1305 */
1306static void
1307xfs_bmap_add_extent_hole_delay(
1308	struct xfs_inode	*ip,	/* incore inode pointer */
1309	int			whichfork,
1310	struct xfs_iext_cursor	*icur,
1311	struct xfs_bmbt_irec	*new)	/* new data to add to file extents */
1312{
1313	struct xfs_ifork	*ifp;	/* inode fork pointer */
1314	xfs_bmbt_irec_t		left;	/* left neighbor extent entry */
1315	xfs_filblks_t		newlen=0;	/* new indirect size */
1316	xfs_filblks_t		oldlen=0;	/* old indirect size */
1317	xfs_bmbt_irec_t		right;	/* right neighbor extent entry */
1318	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
1319	xfs_filblks_t		temp;	 /* temp for indirect calculations */
1320
1321	ifp = xfs_ifork_ptr(ip, whichfork);
1322	ASSERT(isnullstartblock(new->br_startblock));
1323
1324	/*
1325	 * Check and set flags if this segment has a left neighbor
1326	 */
1327	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
1328		state |= BMAP_LEFT_VALID;
1329		if (isnullstartblock(left.br_startblock))
1330			state |= BMAP_LEFT_DELAY;
1331	}
1332
1333	/*
1334	 * Check and set flags if the current (right) segment exists.
1335	 * If it doesn't exist, we're converting the hole at end-of-file.
1336	 */
1337	if (xfs_iext_get_extent(ifp, icur, &right)) {
1338		state |= BMAP_RIGHT_VALID;
1339		if (isnullstartblock(right.br_startblock))
1340			state |= BMAP_RIGHT_DELAY;
1341	}
1342
1343	/*
1344	 * Set contiguity flags on the left and right neighbors.
1345	 * Don't let extents get too large, even if the pieces are contiguous.
1346	 */
1347	if ((state & BMAP_LEFT_VALID) && (state & BMAP_LEFT_DELAY) &&
1348	    left.br_startoff + left.br_blockcount == new->br_startoff &&
1349	    left.br_blockcount + new->br_blockcount <= XFS_MAX_BMBT_EXTLEN)
1350		state |= BMAP_LEFT_CONTIG;
1351
1352	if ((state & BMAP_RIGHT_VALID) && (state & BMAP_RIGHT_DELAY) &&
1353	    new->br_startoff + new->br_blockcount == right.br_startoff &&
1354	    new->br_blockcount + right.br_blockcount <= XFS_MAX_BMBT_EXTLEN &&
1355	    (!(state & BMAP_LEFT_CONTIG) ||
1356	     (left.br_blockcount + new->br_blockcount +
1357	      right.br_blockcount <= XFS_MAX_BMBT_EXTLEN)))
1358		state |= BMAP_RIGHT_CONTIG;
1359
1360	/*
1361	 * Switch out based on the contiguity flags.
1362	 */
1363	switch (state & (BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG)) {
1364	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
1365		/*
1366		 * New allocation is contiguous with delayed allocations
1367		 * on the left and on the right.
1368		 * Merge all three into a single extent record.
1369		 */
1370		temp = left.br_blockcount + new->br_blockcount +
1371			right.br_blockcount;
1372
1373		oldlen = startblockval(left.br_startblock) +
1374			startblockval(new->br_startblock) +
1375			startblockval(right.br_startblock);
1376		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
1377					 oldlen);
1378		left.br_startblock = nullstartblock(newlen);
1379		left.br_blockcount = temp;
1380
1381		xfs_iext_remove(ip, icur, state);
1382		xfs_iext_prev(ifp, icur);
1383		xfs_iext_update_extent(ip, state, icur, &left);
1384		break;
1385
1386	case BMAP_LEFT_CONTIG:
1387		/*
1388		 * New allocation is contiguous with a delayed allocation
1389		 * on the left.
1390		 * Merge the new allocation with the left neighbor.
1391		 */
1392		temp = left.br_blockcount + new->br_blockcount;
1393
1394		oldlen = startblockval(left.br_startblock) +
1395			startblockval(new->br_startblock);
1396		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
1397					 oldlen);
1398		left.br_blockcount = temp;
1399		left.br_startblock = nullstartblock(newlen);
1400
1401		xfs_iext_prev(ifp, icur);
1402		xfs_iext_update_extent(ip, state, icur, &left);
1403		break;
1404
1405	case BMAP_RIGHT_CONTIG:
1406		/*
1407		 * New allocation is contiguous with a delayed allocation
1408		 * on the right.
1409		 * Merge the new allocation with the right neighbor.
1410		 */
1411		temp = new->br_blockcount + right.br_blockcount;
1412		oldlen = startblockval(new->br_startblock) +
1413			startblockval(right.br_startblock);
1414		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
1415					 oldlen);
1416		right.br_startoff = new->br_startoff;
1417		right.br_startblock = nullstartblock(newlen);
1418		right.br_blockcount = temp;
1419		xfs_iext_update_extent(ip, state, icur, &right);
1420		break;
1421
1422	case 0:
1423		/*
1424		 * New allocation is not contiguous with another
1425		 * delayed allocation.
1426		 * Insert a new entry.
1427		 */
1428		oldlen = newlen = 0;
1429		xfs_iext_insert(ip, icur, new, state);
1430		break;
1431	}
1432	if (oldlen != newlen) {
1433		ASSERT(oldlen > newlen);
1434		xfs_add_fdblocks(ip->i_mount, oldlen - newlen);
1435
1436		/*
1437		 * Nothing to do for disk quota accounting here.
1438		 */
1439		xfs_mod_delalloc(ip, 0, (int64_t)newlen - oldlen);
1440	}
1441}
1442
1443/*
1444 * Add a delayed allocation extent to an inode. Blocks are reserved from the
1445 * global pool and the extent inserted into the inode in-core extent tree.
1446 *
1447 * On entry, got refers to the first extent beyond the offset of the extent to
1448 * allocate or eof is specified if no such extent exists. On return, got refers
1449 * to the extent record that was inserted to the inode fork.
1450 *
1451 * Note that the allocated extent may have been merged with contiguous extents
1452 * during insertion into the inode fork. Thus, got does not reflect the current
1453 * state of the inode fork on return. If necessary, the caller can use lastx to
1454 * look up the updated record in the inode fork.
1455 */
1456static int
1457xfs_bmapi_reserve_delalloc(
1458	struct xfs_inode	*ip,
1459	int			whichfork,
1460	xfs_fileoff_t		off,
1461	xfs_filblks_t		len,
1462	xfs_filblks_t		prealloc,
1463	struct xfs_bmbt_irec	*got,
1464	struct xfs_iext_cursor	*icur,
1465	int			eof)
1466{
1467	struct xfs_mount	*mp = ip->i_mount;
1468	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
1469	xfs_extlen_t		alen;
1470	xfs_extlen_t		indlen;
1471	uint64_t		fdblocks;
1472	int			error;
1473	xfs_fileoff_t		aoff;
1474	bool			use_cowextszhint =
1475					whichfork == XFS_COW_FORK && !prealloc;
1476
1477retry:
1478	/*
1479	 * Cap the alloc length. Keep track of prealloc so we know whether to
1480	 * tag the inode before we return.
1481	 */
1482	aoff = off;
1483	alen = XFS_FILBLKS_MIN(len + prealloc, XFS_MAX_BMBT_EXTLEN);
1484	if (!eof)
1485		alen = XFS_FILBLKS_MIN(alen, got->br_startoff - aoff);
1486	if (prealloc && alen >= len)
1487		prealloc = alen - len;
1488
1489	/*
1490	 * If we're targetting the COW fork but aren't creating a speculative
1491	 * posteof preallocation, try to expand the reservation to align with
1492	 * the COW extent size hint if there's sufficient free space.
1493	 *
1494	 * Unlike the data fork, the CoW cancellation functions will free all
1495	 * the reservations at inactivation, so we don't require that every
1496	 * delalloc reservation have a dirty pagecache.
1497	 */
1498	if (use_cowextszhint) {
1499		struct xfs_bmbt_irec	prev;
1500		xfs_extlen_t		extsz = xfs_get_cowextsz_hint(ip);
1501
1502		if (!xfs_iext_peek_prev_extent(ifp, icur, &prev))
1503			prev.br_startoff = NULLFILEOFF;
1504
1505		error = xfs_bmap_extsize_align(mp, got, &prev, extsz, 0, eof,
1506					       1, 0, &aoff, &alen);
1507		ASSERT(!error);
1508	}
1509
1510	/*
1511	 * Make a transaction-less quota reservation for delayed allocation
1512	 * blocks.  This number gets adjusted later.  We return if we haven't
1513	 * allocated blocks already inside this loop.
1514	 */
1515	error = xfs_quota_reserve_blkres(ip, alen);
1516	if (error)
1517		goto out;
1518
1519	/*
1520	 * Split changing sb for alen and indlen since they could be coming
1521	 * from different places.
1522	 */
1523	indlen = (xfs_extlen_t)xfs_bmap_worst_indlen(ip, alen);
1524	ASSERT(indlen > 0);
1525
1526	fdblocks = indlen;
1527	if (XFS_IS_REALTIME_INODE(ip)) {
1528		ASSERT(!xfs_is_zoned_inode(ip));
1529		error = xfs_dec_frextents(mp, xfs_blen_to_rtbxlen(mp, alen));
1530		if (error)
1531			goto out_unreserve_quota;
1532	} else {
1533		fdblocks += alen;
1534	}
1535
1536	error = xfs_dec_fdblocks(mp, fdblocks, false);
1537	if (error)
1538		goto out_unreserve_frextents;
1539
1540	ip->i_delayed_blks += alen;
1541	xfs_mod_delalloc(ip, alen, indlen);
1542
1543	got->br_startoff = aoff;
1544	got->br_startblock = nullstartblock(indlen);
1545	got->br_blockcount = alen;
1546	got->br_state = XFS_EXT_NORM;
1547
1548	xfs_bmap_add_extent_hole_delay(ip, whichfork, icur, got);
1549
1550	/*
1551	 * Tag the inode if blocks were preallocated. Note that COW fork
1552	 * preallocation can occur at the start or end of the extent, even when
1553	 * prealloc == 0, so we must also check the aligned offset and length.
1554	 */
1555	if (whichfork == XFS_DATA_FORK && prealloc)
1556		xfs_inode_set_eofblocks_tag(ip);
1557	if (whichfork == XFS_COW_FORK && (prealloc || aoff < off || alen > len))
1558		xfs_inode_set_cowblocks_tag(ip);
1559
1560	return 0;
1561
1562out_unreserve_frextents:
1563	if (XFS_IS_REALTIME_INODE(ip))
1564		xfs_add_frextents(mp, xfs_blen_to_rtbxlen(mp, alen));
1565out_unreserve_quota:
1566	if (XFS_IS_QUOTA_ON(mp))
1567		xfs_quota_unreserve_blkres(ip, alen);
1568out:
1569	if (error == -ENOSPC || error == -EDQUOT) {
1570		trace_xfs_delalloc_enospc(ip, off, len);
1571
1572		if (prealloc || use_cowextszhint) {
1573			/* retry without any preallocation */
1574			use_cowextszhint = false;
1575			prealloc = 0;
1576			goto retry;
1577		}
1578	}
1579	return error;
1580}
1581
1582static int
1583xfs_zoned_buffered_write_iomap_begin(
1584	struct inode		*inode,
1585	loff_t			offset,
1586	loff_t			count,
1587	unsigned		flags,
1588	struct iomap		*iomap,
1589	struct iomap		*srcmap)
1590{
1591	struct iomap_iter	*iter =
1592		container_of(iomap, struct iomap_iter, iomap);
1593	struct xfs_zone_alloc_ctx *ac = iter->private;
1594	struct xfs_inode	*ip = XFS_I(inode);
1595	struct xfs_mount	*mp = ip->i_mount;
1596	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
1597	xfs_fileoff_t		end_fsb = xfs_iomap_end_fsb(mp, offset, count);
1598	u16			iomap_flags = IOMAP_F_SHARED;
1599	unsigned int		lockmode = XFS_ILOCK_EXCL;
1600	xfs_filblks_t		count_fsb;
1601	xfs_extlen_t		indlen;
1602	struct xfs_bmbt_irec	got;
1603	struct xfs_iext_cursor	icur;
1604	int			error = 0;
1605
1606	ASSERT(!xfs_get_extsz_hint(ip));
1607	ASSERT(!(flags & IOMAP_UNSHARE));
1608	ASSERT(ac);
1609
1610	if (xfs_is_shutdown(mp))
1611		return -EIO;
1612
1613	error = xfs_qm_dqattach(ip);
1614	if (error)
1615		return error;
1616
1617	error = xfs_ilock_for_iomap(ip, flags, &lockmode);
1618	if (error)
1619		return error;
1620
1621	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(&ip->i_df)) ||
1622	    XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
1623		xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
1624		error = -EFSCORRUPTED;
1625		goto out_unlock;
1626	}
1627
1628	XFS_STATS_INC(mp, xs_blk_mapw);
1629
1630	error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
1631	if (error)
1632		goto out_unlock;
1633
1634	/*
1635	 * For zeroing operations check if there is any data to zero first.
1636	 *
1637	 * For regular writes we always need to allocate new blocks, but need to
1638	 * provide the source mapping when the range is unaligned to support
1639	 * read-modify-write of the whole block in the page cache.
1640	 *
1641	 * In either case we need to limit the reported range to the boundaries
1642	 * of the source map in the data fork.
1643	 */
1644	if (!IS_ALIGNED(offset, mp->m_sb.sb_blocksize) ||
1645	    !IS_ALIGNED(offset + count, mp->m_sb.sb_blocksize) ||
1646	    (flags & IOMAP_ZERO)) {
1647		struct xfs_bmbt_irec	smap;
1648		struct xfs_iext_cursor	scur;
1649
1650		if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &scur,
1651				&smap))
1652			smap.br_startoff = end_fsb; /* fake hole until EOF */
1653		if (smap.br_startoff > offset_fsb) {
1654			/*
1655			 * We never need to allocate blocks for zeroing a hole.
1656			 */
1657			if (flags & IOMAP_ZERO) {
1658				xfs_hole_to_iomap(ip, iomap, offset_fsb,
1659						smap.br_startoff);
1660				goto out_unlock;
1661			}
1662			end_fsb = min(end_fsb, smap.br_startoff);
1663		} else {
1664			end_fsb = min(end_fsb,
1665				smap.br_startoff + smap.br_blockcount);
1666			xfs_trim_extent(&smap, offset_fsb,
1667					end_fsb - offset_fsb);
1668			error = xfs_bmbt_to_iomap(ip, srcmap, &smap, flags, 0,
1669					xfs_iomap_inode_sequence(ip, 0));
1670			if (error)
1671				goto out_unlock;
1672		}
1673	}
1674
1675	if (!ip->i_cowfp)
1676		xfs_ifork_init_cow(ip);
1677
1678	if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got))
1679		got.br_startoff = end_fsb;
1680	if (got.br_startoff <= offset_fsb) {
1681		trace_xfs_reflink_cow_found(ip, &got);
1682		goto done;
1683	}
1684
1685	/*
1686	 * Cap the maximum length to keep the chunks of work done here somewhat
1687	 * symmetric with the work writeback does.
1688	 */
1689	end_fsb = min(end_fsb, got.br_startoff);
1690	count_fsb = min3(end_fsb - offset_fsb, XFS_MAX_BMBT_EXTLEN,
1691			 XFS_B_TO_FSB(mp, 1024 * PAGE_SIZE));
1692
1693	/*
1694	 * The block reservation is supposed to cover all blocks that the
1695	 * operation could possible write, but there is a nasty corner case
1696	 * where blocks could be stolen from underneath us:
1697	 *
1698	 *  1) while this thread iterates over a larger buffered write,
1699	 *  2) another thread is causing a write fault that calls into
1700	 *     ->page_mkwrite in range this thread writes to, using up the
1701	 *     delalloc reservation created by a previous call to this function.
1702	 *  3) another thread does direct I/O on the range that the write fault
1703	 *     happened on, which causes writeback of the dirty data.
1704	 *  4) this then set the stale flag, which cuts the current iomap
1705	 *     iteration short, causing the new call to ->iomap_begin that gets
1706	 *     us here again, but now without a sufficient reservation.
1707	 *
1708	 * This is a very unusual I/O pattern, and nothing but generic/095 is
1709	 * known to hit it. There's not really much we can do here, so turn this
1710	 * into a short write.
1711	 */
1712	if (count_fsb > ac->reserved_blocks) {
1713		xfs_warn_ratelimited(mp,
1714"Short write on ino 0x%llx comm %.20s due to three-way race with write fault and direct I/O",
1715			ip->i_ino, current->comm);
1716		count_fsb = ac->reserved_blocks;
1717		if (!count_fsb) {
1718			error = -EIO;
1719			goto out_unlock;
1720		}
1721	}
1722
1723	error = xfs_quota_reserve_blkres(ip, count_fsb);
1724	if (error)
1725		goto out_unlock;
1726
1727	indlen = xfs_bmap_worst_indlen(ip, count_fsb);
1728	error = xfs_dec_fdblocks(mp, indlen, false);
1729	if (error)
1730		goto out_unlock;
1731	ip->i_delayed_blks += count_fsb;
1732	xfs_mod_delalloc(ip, count_fsb, indlen);
1733
1734	got.br_startoff = offset_fsb;
1735	got.br_startblock = nullstartblock(indlen);
1736	got.br_blockcount = count_fsb;
1737	got.br_state = XFS_EXT_NORM;
1738	xfs_bmap_add_extent_hole_delay(ip, XFS_COW_FORK, &icur, &got);
1739	ac->reserved_blocks -= count_fsb;
1740	iomap_flags |= IOMAP_F_NEW;
1741
1742	trace_xfs_iomap_alloc(ip, offset, XFS_FSB_TO_B(mp, count_fsb),
1743			XFS_COW_FORK, &got);
1744done:
1745	error = xfs_bmbt_to_iomap(ip, iomap, &got, flags, iomap_flags,
1746			xfs_iomap_inode_sequence(ip, IOMAP_F_SHARED));
1747out_unlock:
1748	xfs_iunlock(ip, lockmode);
1749	return error;
1750}
1751
1752static int
1753xfs_buffered_write_iomap_begin(
1754	struct inode		*inode,
1755	loff_t			offset,
1756	loff_t			count,
1757	unsigned		flags,
1758	struct iomap		*iomap,
1759	struct iomap		*srcmap)
1760{
1761	struct iomap_iter	*iter = container_of(iomap, struct iomap_iter,
1762						     iomap);
1763	struct xfs_inode	*ip = XFS_I(inode);
1764	struct xfs_mount	*mp = ip->i_mount;
1765	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
1766	xfs_fileoff_t		end_fsb = xfs_iomap_end_fsb(mp, offset, count);
1767	struct xfs_bmbt_irec	imap, cmap;
1768	struct xfs_iext_cursor	icur, ccur;
1769	xfs_fsblock_t		prealloc_blocks = 0;
1770	bool			eof = false, cow_eof = false, shared = false;
1771	int			allocfork = XFS_DATA_FORK;
1772	int			error = 0;
1773	unsigned int		lockmode = XFS_ILOCK_EXCL;
1774	unsigned int		iomap_flags = 0;
1775	u64			seq;
1776
1777	if (xfs_is_shutdown(mp))
1778		return -EIO;
1779
1780	if (xfs_is_zoned_inode(ip))
1781		return xfs_zoned_buffered_write_iomap_begin(inode, offset,
1782				count, flags, iomap, srcmap);
1783
1784	/* we can't use delayed allocations when using extent size hints */
1785	if (xfs_get_extsz_hint(ip))
1786		return xfs_direct_write_iomap_begin(inode, offset, count,
1787				flags, iomap, srcmap);
1788
1789	error = xfs_qm_dqattach(ip);
1790	if (error)
1791		return error;
1792
1793	error = xfs_ilock_for_iomap(ip, flags, &lockmode);
1794	if (error)
1795		return error;
1796
1797	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(&ip->i_df)) ||
1798	    XFS_TEST_ERROR(mp, XFS_ERRTAG_BMAPIFORMAT)) {
1799		xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
1800		error = -EFSCORRUPTED;
1801		goto out_unlock;
1802	}
1803
1804	XFS_STATS_INC(mp, xs_blk_mapw);
1805
1806	error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
1807	if (error)
1808		goto out_unlock;
1809
1810	/*
1811	 * Search the data fork first to look up our source mapping.  We
1812	 * always need the data fork map, as we have to return it to the
1813	 * iomap code so that the higher level write code can read data in to
1814	 * perform read-modify-write cycles for unaligned writes.
1815	 */
1816	eof = !xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap);
1817	if (eof)
1818		imap.br_startoff = end_fsb; /* fake hole until the end */
1819
1820	/* We never need to allocate blocks for zeroing or unsharing a hole. */
1821	if ((flags & (IOMAP_UNSHARE | IOMAP_ZERO)) &&
1822	    imap.br_startoff > offset_fsb) {
1823		xfs_hole_to_iomap(ip, iomap, offset_fsb, imap.br_startoff);
1824		goto out_unlock;
1825	}
1826
1827	/*
1828	 * For zeroing, trim extents that extend beyond the EOF block. If a
1829	 * delalloc extent starts beyond the EOF block, convert it to an
1830	 * unwritten extent.
1831	 */
1832	if (flags & IOMAP_ZERO) {
1833		xfs_fileoff_t eof_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
1834
1835		if (isnullstartblock(imap.br_startblock) &&
1836		    offset_fsb >= eof_fsb)
1837			goto convert_delay;
1838		if (offset_fsb < eof_fsb && end_fsb > eof_fsb)
1839			end_fsb = eof_fsb;
1840
1841		/*
1842		 * Look up dirty folios for unwritten mappings within EOF.
1843		 * Providing this bypasses the flush iomap uses to trigger
1844		 * extent conversion when unwritten mappings have dirty
1845		 * pagecache in need of zeroing.
1846		 *
1847		 * Trim the mapping to the end pos of the lookup, which in turn
1848		 * was trimmed to the end of the batch if it became full before
1849		 * the end of the mapping.
1850		 */
1851		if (imap.br_state == XFS_EXT_UNWRITTEN &&
1852		    offset_fsb < eof_fsb) {
1853			loff_t foffset = offset, fend;
1854
1855			fend = offset +
1856			       min(count, XFS_FSB_TO_B(mp, imap.br_blockcount));
1857			iomap_fill_dirty_folios(iter, &foffset, fend,
1858						&iomap_flags);
1859			end_fsb = min_t(xfs_fileoff_t, end_fsb,
1860					XFS_B_TO_FSB(mp, foffset));
1861		}
1862
1863		xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
1864	}
1865
1866	/*
1867	 * Search the COW fork extent list even if we did not find a data fork
1868	 * extent.  This serves two purposes: first this implements the
1869	 * speculative preallocation using cowextsize, so that we also unshare
1870	 * block adjacent to shared blocks instead of just the shared blocks
1871	 * themselves.  Second the lookup in the extent list is generally faster
1872	 * than going out to the shared extent tree.
1873	 */
1874	if (xfs_is_cow_inode(ip)) {
1875		if (!ip->i_cowfp) {
1876			ASSERT(!xfs_is_reflink_inode(ip));
1877			xfs_ifork_init_cow(ip);
1878		}
1879		cow_eof = !xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb,
1880				&ccur, &cmap);
1881		if (!cow_eof && cmap.br_startoff <= offset_fsb) {
1882			trace_xfs_reflink_cow_found(ip, &cmap);
1883			goto found_cow;
1884		}
1885	}
1886
1887	if (imap.br_startoff <= offset_fsb) {
1888		/*
1889		 * For reflink files we may need a delalloc reservation when
1890		 * overwriting shared extents.   This includes zeroing of
1891		 * existing extents that contain data.
1892		 */
1893		if (!xfs_is_cow_inode(ip) ||
1894		    ((flags & IOMAP_ZERO) && imap.br_state != XFS_EXT_NORM)) {
1895			trace_xfs_iomap_found(ip, offset, count, XFS_DATA_FORK,
1896					&imap);
1897			goto found_imap;
1898		}
1899
1900		xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
1901
1902		/* Trim the mapping to the nearest shared extent boundary. */
1903		error = xfs_bmap_trim_cow(ip, &imap, &shared);
1904		if (error)
1905			goto out_unlock;
1906
1907		/* Not shared?  Just report the (potentially capped) extent. */
1908		if (!shared) {
1909			trace_xfs_iomap_found(ip, offset, count, XFS_DATA_FORK,
1910					&imap);
1911			goto found_imap;
1912		}
1913
1914		/*
1915		 * Fork all the shared blocks from our write offset until the
1916		 * end of the extent.
1917		 */
1918		allocfork = XFS_COW_FORK;
1919		end_fsb = imap.br_startoff + imap.br_blockcount;
1920	} else {
1921		/*
1922		 * We cap the maximum length we map here to MAX_WRITEBACK_PAGES
1923		 * pages to keep the chunks of work done where somewhat
1924		 * symmetric with the work writeback does.  This is a completely
1925		 * arbitrary number pulled out of thin air.
1926		 *
1927		 * Note that the values needs to be less than 32-bits wide until
1928		 * the lower level functions are updated.
1929		 */
1930		count = min_t(loff_t, count, 1024 * PAGE_SIZE);
1931		end_fsb = xfs_iomap_end_fsb(mp, offset, count);
1932
1933		if (xfs_is_always_cow_inode(ip))
1934			allocfork = XFS_COW_FORK;
1935	}
1936
1937	if (eof && offset + count > XFS_ISIZE(ip)) {
1938		/*
1939		 * Determine the initial size of the preallocation.
1940		 * We clean up any extra preallocation when the file is closed.
1941		 */
1942		if (xfs_has_allocsize(mp))
1943			prealloc_blocks = mp->m_allocsize_blocks;
1944		else if (allocfork == XFS_DATA_FORK)
1945			prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork,
1946						offset, count, &icur);
1947		else
1948			prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork,
1949						offset, count, &ccur);
1950		if (prealloc_blocks) {
1951			xfs_extlen_t	align;
1952			xfs_off_t	end_offset;
1953			xfs_fileoff_t	p_end_fsb;
1954
1955			end_offset = XFS_ALLOC_ALIGN(mp, offset + count - 1);
1956			p_end_fsb = XFS_B_TO_FSBT(mp, end_offset) +
1957					prealloc_blocks;
1958
1959			align = xfs_eof_alignment(ip);
1960			if (align)
1961				p_end_fsb = roundup_64(p_end_fsb, align);
1962
1963			p_end_fsb = min(p_end_fsb,
1964				XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes));
1965			ASSERT(p_end_fsb > offset_fsb);
1966			prealloc_blocks = p_end_fsb - end_fsb;
1967		}
1968	}
1969
1970	/*
1971	 * Flag newly allocated delalloc blocks with IOMAP_F_NEW so we punch
1972	 * them out if the write happens to fail.
1973	 */
1974	iomap_flags |= IOMAP_F_NEW;
1975	if (allocfork == XFS_COW_FORK) {
1976		error = xfs_bmapi_reserve_delalloc(ip, allocfork, offset_fsb,
1977				end_fsb - offset_fsb, prealloc_blocks, &cmap,
1978				&ccur, cow_eof);
1979		if (error)
1980			goto out_unlock;
1981
1982		trace_xfs_iomap_alloc(ip, offset, count, allocfork, &cmap);
1983		goto found_cow;
1984	}
1985
1986	error = xfs_bmapi_reserve_delalloc(ip, allocfork, offset_fsb,
1987			end_fsb - offset_fsb, prealloc_blocks, &imap, &icur,
1988			eof);
1989	if (error)
1990		goto out_unlock;
1991
1992	trace_xfs_iomap_alloc(ip, offset, count, allocfork, &imap);
1993found_imap:
1994	seq = xfs_iomap_inode_sequence(ip, iomap_flags);
1995	xfs_iunlock(ip, lockmode);
1996	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags, iomap_flags, seq);
1997
1998convert_delay:
1999	xfs_iunlock(ip, lockmode);
2000	truncate_pagecache(inode, offset);
2001	error = xfs_bmapi_convert_delalloc(ip, XFS_DATA_FORK, offset,
2002					   iomap, NULL);
2003	if (error)
2004		return error;
2005
2006	trace_xfs_iomap_alloc(ip, offset, count, XFS_DATA_FORK, &imap);
2007	return 0;
2008
2009found_cow:
2010	if (imap.br_startoff <= offset_fsb) {
2011		error = xfs_bmbt_to_iomap(ip, srcmap, &imap, flags, 0,
2012				xfs_iomap_inode_sequence(ip, 0));
2013		if (error)
2014			goto out_unlock;
2015	} else {
2016		xfs_trim_extent(&cmap, offset_fsb,
2017				imap.br_startoff - offset_fsb);
2018	}
2019
2020	iomap_flags |= IOMAP_F_SHARED;
2021	seq = xfs_iomap_inode_sequence(ip, iomap_flags);
2022	xfs_iunlock(ip, lockmode);
2023	return xfs_bmbt_to_iomap(ip, iomap, &cmap, flags, iomap_flags, seq);
2024
2025out_unlock:
2026	xfs_iunlock(ip, lockmode);
2027	return error;
2028}
2029
2030static void
2031xfs_buffered_write_delalloc_punch(
2032	struct inode		*inode,
2033	loff_t			offset,
2034	loff_t			length,
2035	struct iomap		*iomap)
2036{
2037	struct iomap_iter	*iter =
2038		container_of(iomap, struct iomap_iter, iomap);
2039
2040	xfs_bmap_punch_delalloc_range(XFS_I(inode),
2041			(iomap->flags & IOMAP_F_SHARED) ?
2042				XFS_COW_FORK : XFS_DATA_FORK,
2043			offset, offset + length, iter->private);
2044}
2045
2046static int
2047xfs_buffered_write_iomap_end(
2048	struct inode		*inode,
2049	loff_t			offset,
2050	loff_t			length,
2051	ssize_t			written,
2052	unsigned		flags,
2053	struct iomap		*iomap)
2054{
2055	loff_t			start_byte, end_byte;
2056
2057	/* If we didn't reserve the blocks, we're not allowed to punch them. */
2058	if (iomap->type != IOMAP_DELALLOC || !(iomap->flags & IOMAP_F_NEW))
2059		return 0;
2060
2061	/*
2062	 * iomap_page_mkwrite() will never fail in a way that requires delalloc
2063	 * extents that it allocated to be revoked.  Hence never try to release
2064	 * them here.
2065	 */
2066	if (flags & IOMAP_FAULT)
2067		return 0;
2068
2069	/* Nothing to do if we've written the entire delalloc extent */
2070	start_byte = iomap_last_written_block(inode, offset, written);
2071	end_byte = round_up(offset + length, i_blocksize(inode));
2072	if (start_byte >= end_byte)
2073		return 0;
2074
2075	/* For zeroing operations the callers already hold invalidate_lock. */
2076	if (flags & (IOMAP_UNSHARE | IOMAP_ZERO)) {
2077		rwsem_assert_held_write(&inode->i_mapping->invalidate_lock);
2078		iomap_write_delalloc_release(inode, start_byte, end_byte, flags,
2079				iomap, xfs_buffered_write_delalloc_punch);
2080	} else {
2081		filemap_invalidate_lock(inode->i_mapping);
2082		iomap_write_delalloc_release(inode, start_byte, end_byte, flags,
2083				iomap, xfs_buffered_write_delalloc_punch);
2084		filemap_invalidate_unlock(inode->i_mapping);
2085	}
2086
2087	return 0;
2088}
2089
2090const struct iomap_ops xfs_buffered_write_iomap_ops = {
2091	.iomap_begin		= xfs_buffered_write_iomap_begin,
2092	.iomap_end		= xfs_buffered_write_iomap_end,
2093};
2094
2095static int
2096xfs_read_iomap_begin(
2097	struct inode		*inode,
2098	loff_t			offset,
2099	loff_t			length,
2100	unsigned		flags,
2101	struct iomap		*iomap,
2102	struct iomap		*srcmap)
2103{
2104	struct xfs_inode	*ip = XFS_I(inode);
2105	struct xfs_mount	*mp = ip->i_mount;
2106	struct xfs_bmbt_irec	imap;
2107	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
2108	xfs_fileoff_t		end_fsb = xfs_iomap_end_fsb(mp, offset, length);
2109	int			nimaps = 1, error = 0;
2110	bool			shared = false;
2111	unsigned int		lockmode = XFS_ILOCK_SHARED;
2112	u64			seq;
2113
2114	ASSERT(!(flags & (IOMAP_WRITE | IOMAP_ZERO)));
2115
2116	if (xfs_is_shutdown(mp))
2117		return -EIO;
2118
2119	error = xfs_ilock_for_iomap(ip, flags, &lockmode);
2120	if (error)
2121		return error;
2122	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
2123			       &nimaps, 0);
2124	if (!error && ((flags & IOMAP_REPORT) || IS_DAX(inode)))
2125		error = xfs_reflink_trim_around_shared(ip, &imap, &shared);
2126	seq = xfs_iomap_inode_sequence(ip, shared ? IOMAP_F_SHARED : 0);
2127	xfs_iunlock(ip, lockmode);
2128
2129	if (error)
2130		return error;
2131	trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
2132	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags,
2133				 shared ? IOMAP_F_SHARED : 0, seq);
2134}
2135
2136const struct iomap_ops xfs_read_iomap_ops = {
2137	.iomap_begin		= xfs_read_iomap_begin,
2138};
2139
2140static int
2141xfs_seek_iomap_begin(
2142	struct inode		*inode,
2143	loff_t			offset,
2144	loff_t			length,
2145	unsigned		flags,
2146	struct iomap		*iomap,
2147	struct iomap		*srcmap)
2148{
2149	struct xfs_inode	*ip = XFS_I(inode);
2150	struct xfs_mount	*mp = ip->i_mount;
2151	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
2152	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + length);
2153	xfs_fileoff_t		cow_fsb = NULLFILEOFF, data_fsb = NULLFILEOFF;
2154	struct xfs_iext_cursor	icur;
2155	struct xfs_bmbt_irec	imap, cmap;
2156	int			error = 0;
2157	unsigned		lockmode;
2158	u64			seq;
2159
2160	if (xfs_is_shutdown(mp))
2161		return -EIO;
2162
2163	lockmode = xfs_ilock_data_map_shared(ip);
2164	error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
2165	if (error)
2166		goto out_unlock;
2167
2168	if (xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap)) {
2169		/*
2170		 * If we found a data extent we are done.
2171		 */
2172		if (imap.br_startoff <= offset_fsb)
2173			goto done;
2174		data_fsb = imap.br_startoff;
2175	} else {
2176		/*
2177		 * Fake a hole until the end of the file.
2178		 */
2179		data_fsb = xfs_iomap_end_fsb(mp, offset, length);
2180	}
2181
2182	/*
2183	 * If a COW fork extent covers the hole, report it - capped to the next
2184	 * data fork extent:
2185	 */
2186	if (xfs_inode_has_cow_data(ip) &&
2187	    xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &cmap))
2188		cow_fsb = cmap.br_startoff;
2189	if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) {
2190		if (data_fsb < cow_fsb + cmap.br_blockcount)
2191			end_fsb = min(end_fsb, data_fsb);
2192		xfs_trim_extent(&cmap, offset_fsb, end_fsb - offset_fsb);
2193		seq = xfs_iomap_inode_sequence(ip, IOMAP_F_SHARED);
2194		error = xfs_bmbt_to_iomap(ip, iomap, &cmap, flags,
2195				IOMAP_F_SHARED, seq);
2196		/*
2197		 * This is a COW extent, so we must probe the page cache
2198		 * because there could be dirty page cache being backed
2199		 * by this extent.
2200		 */
2201		iomap->type = IOMAP_UNWRITTEN;
2202		goto out_unlock;
2203	}
2204
2205	/*
2206	 * Else report a hole, capped to the next found data or COW extent.
2207	 */
2208	if (cow_fsb != NULLFILEOFF && cow_fsb < data_fsb)
2209		imap.br_blockcount = cow_fsb - offset_fsb;
2210	else
2211		imap.br_blockcount = data_fsb - offset_fsb;
2212	imap.br_startoff = offset_fsb;
2213	imap.br_startblock = HOLESTARTBLOCK;
2214	imap.br_state = XFS_EXT_NORM;
2215done:
2216	seq = xfs_iomap_inode_sequence(ip, 0);
2217	xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
2218	error = xfs_bmbt_to_iomap(ip, iomap, &imap, flags, 0, seq);
2219out_unlock:
2220	xfs_iunlock(ip, lockmode);
2221	return error;
2222}
2223
2224const struct iomap_ops xfs_seek_iomap_ops = {
2225	.iomap_begin		= xfs_seek_iomap_begin,
2226};
2227
2228static int
2229xfs_xattr_iomap_begin(
2230	struct inode		*inode,
2231	loff_t			offset,
2232	loff_t			length,
2233	unsigned		flags,
2234	struct iomap		*iomap,
2235	struct iomap		*srcmap)
2236{
2237	struct xfs_inode	*ip = XFS_I(inode);
2238	struct xfs_mount	*mp = ip->i_mount;
2239	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
2240	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + length);
2241	struct xfs_bmbt_irec	imap;
2242	int			nimaps = 1, error = 0;
2243	unsigned		lockmode;
2244	int			seq;
2245
2246	if (xfs_is_shutdown(mp))
2247		return -EIO;
2248
2249	lockmode = xfs_ilock_attr_map_shared(ip);
2250
2251	/* if there are no attribute fork or extents, return ENOENT */
2252	if (!xfs_inode_has_attr_fork(ip) || !ip->i_af.if_nextents) {
2253		error = -ENOENT;
2254		goto out_unlock;
2255	}
2256
2257	ASSERT(ip->i_af.if_format != XFS_DINODE_FMT_LOCAL);
2258	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
2259			       &nimaps, XFS_BMAPI_ATTRFORK);
2260out_unlock:
2261
2262	seq = xfs_iomap_inode_sequence(ip, IOMAP_F_XATTR);
2263	xfs_iunlock(ip, lockmode);
2264
2265	if (error)
2266		return error;
2267	ASSERT(nimaps);
2268	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags, IOMAP_F_XATTR, seq);
2269}
2270
2271const struct iomap_ops xfs_xattr_iomap_ops = {
2272	.iomap_begin		= xfs_xattr_iomap_begin,
2273};
2274
2275int
2276xfs_zero_range(
2277	struct xfs_inode	*ip,
2278	loff_t			pos,
2279	loff_t			len,
2280	struct xfs_zone_alloc_ctx *ac,
2281	bool			*did_zero)
2282{
2283	struct inode		*inode = VFS_I(ip);
2284
2285	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
2286
2287	if (IS_DAX(inode))
2288		return dax_zero_range(inode, pos, len, did_zero,
2289				      &xfs_dax_write_iomap_ops);
2290	return iomap_zero_range(inode, pos, len, did_zero,
2291			&xfs_buffered_write_iomap_ops, &xfs_iomap_write_ops,
2292			ac);
2293}
2294
2295int
2296xfs_truncate_page(
2297	struct xfs_inode	*ip,
2298	loff_t			pos,
2299	struct xfs_zone_alloc_ctx *ac,
2300	bool			*did_zero)
2301{
2302	struct inode		*inode = VFS_I(ip);
2303
2304	if (IS_DAX(inode))
2305		return dax_truncate_page(inode, pos, did_zero,
2306					&xfs_dax_write_iomap_ops);
2307	return iomap_truncate_page(inode, pos, did_zero,
2308			&xfs_buffered_write_iomap_ops, &xfs_iomap_write_ops,
2309			ac);
2310}