1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2010 Red Hat, Inc.
   4 * Copyright (C) 2016-2023 Christoph Hellwig.
   5 */
   6#include <linux/module.h>
   7#include <linux/compiler.h>
   8#include <linux/fs.h>
   9#include <linux/iomap.h>
  10#include <linux/pagemap.h>
  11#include <linux/uio.h>
  12#include <linux/buffer_head.h>
  13#include <linux/dax.h>
  14#include <linux/writeback.h>
  15#include <linux/list_sort.h>
  16#include <linux/swap.h>
  17#include <linux/bio.h>
  18#include <linux/sched/signal.h>
  19#include <linux/migrate.h>
  20#include "trace.h"
  21
  22#include "../internal.h"
  23
  24#define IOEND_BATCH_SIZE	4096
  25
  26/*
  27 * Structure allocated for each folio to track per-block uptodate, dirty state
  28 * and I/O completions.
  29 */
  30struct iomap_folio_state {
  31	spinlock_t		state_lock;
  32	unsigned int		read_bytes_pending;
  33	atomic_t		write_bytes_pending;
  34
  35	/*
  36	 * Each block has two bits in this bitmap:
  37	 * Bits [0..blocks_per_folio) has the uptodate status.
  38	 * Bits [b_p_f...(2*b_p_f))   has the dirty status.
  39	 */
  40	unsigned long		state[];
  41};
  42
  43static struct bio_set iomap_ioend_bioset;
  44
  45static inline bool ifs_is_fully_uptodate(struct folio *folio,
  46		struct iomap_folio_state *ifs)
  47{
  48	struct inode *inode = folio->mapping->host;
  49
  50	return bitmap_full(ifs->state, i_blocks_per_folio(inode, folio));
  51}
  52
  53static inline bool ifs_block_is_uptodate(struct iomap_folio_state *ifs,
  54		unsigned int block)
  55{
  56	return test_bit(block, ifs->state);
  57}
  58
  59static bool ifs_set_range_uptodate(struct folio *folio,
  60		struct iomap_folio_state *ifs, size_t off, size_t len)
  61{
  62	struct inode *inode = folio->mapping->host;
  63	unsigned int first_blk = off >> inode->i_blkbits;
  64	unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
  65	unsigned int nr_blks = last_blk - first_blk + 1;
  66
  67	bitmap_set(ifs->state, first_blk, nr_blks);
  68	return ifs_is_fully_uptodate(folio, ifs);
  69}
  70
  71static void iomap_set_range_uptodate(struct folio *folio, size_t off,
  72		size_t len)
  73{
  74	struct iomap_folio_state *ifs = folio->private;
  75	unsigned long flags;
  76	bool uptodate = true;
  77
  78	if (ifs) {
  79		spin_lock_irqsave(&ifs->state_lock, flags);
  80		uptodate = ifs_set_range_uptodate(folio, ifs, off, len);
  81		spin_unlock_irqrestore(&ifs->state_lock, flags);
  82	}
  83
  84	if (uptodate)
  85		folio_mark_uptodate(folio);
  86}
  87
  88static inline bool ifs_block_is_dirty(struct folio *folio,
  89		struct iomap_folio_state *ifs, int block)
  90{
  91	struct inode *inode = folio->mapping->host;
  92	unsigned int blks_per_folio = i_blocks_per_folio(inode, folio);
  93
  94	return test_bit(block + blks_per_folio, ifs->state);
  95}
  96
  97static unsigned ifs_find_dirty_range(struct folio *folio,
  98		struct iomap_folio_state *ifs, u64 *range_start, u64 range_end)
  99{
 100	struct inode *inode = folio->mapping->host;
 101	unsigned start_blk =
 102		offset_in_folio(folio, *range_start) >> inode->i_blkbits;
 103	unsigned end_blk = min_not_zero(
 104		offset_in_folio(folio, range_end) >> inode->i_blkbits,
 105		i_blocks_per_folio(inode, folio));
 106	unsigned nblks = 1;
 107
 108	while (!ifs_block_is_dirty(folio, ifs, start_blk))
 109		if (++start_blk == end_blk)
 110			return 0;
 111
 112	while (start_blk + nblks < end_blk) {
 113		if (!ifs_block_is_dirty(folio, ifs, start_blk + nblks))
 114			break;
 115		nblks++;
 116	}
 117
 118	*range_start = folio_pos(folio) + (start_blk << inode->i_blkbits);
 119	return nblks << inode->i_blkbits;
 120}
 121
 122static unsigned iomap_find_dirty_range(struct folio *folio, u64 *range_start,
 123		u64 range_end)
 124{
 125	struct iomap_folio_state *ifs = folio->private;
 126
 127	if (*range_start >= range_end)
 128		return 0;
 129
 130	if (ifs)
 131		return ifs_find_dirty_range(folio, ifs, range_start, range_end);
 132	return range_end - *range_start;
 133}
 134
 135static void ifs_clear_range_dirty(struct folio *folio,
 136		struct iomap_folio_state *ifs, size_t off, size_t len)
 137{
 138	struct inode *inode = folio->mapping->host;
 139	unsigned int blks_per_folio = i_blocks_per_folio(inode, folio);
 140	unsigned int first_blk = (off >> inode->i_blkbits);
 141	unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
 142	unsigned int nr_blks = last_blk - first_blk + 1;
 143	unsigned long flags;
 144
 145	spin_lock_irqsave(&ifs->state_lock, flags);
 146	bitmap_clear(ifs->state, first_blk + blks_per_folio, nr_blks);
 147	spin_unlock_irqrestore(&ifs->state_lock, flags);
 148}
 149
 150static void iomap_clear_range_dirty(struct folio *folio, size_t off, size_t len)
 151{
 152	struct iomap_folio_state *ifs = folio->private;
 153
 154	if (ifs)
 155		ifs_clear_range_dirty(folio, ifs, off, len);
 156}
 157
 158static void ifs_set_range_dirty(struct folio *folio,
 159		struct iomap_folio_state *ifs, size_t off, size_t len)
 160{
 161	struct inode *inode = folio->mapping->host;
 162	unsigned int blks_per_folio = i_blocks_per_folio(inode, folio);
 163	unsigned int first_blk = (off >> inode->i_blkbits);
 164	unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
 165	unsigned int nr_blks = last_blk - first_blk + 1;
 166	unsigned long flags;
 167
 168	spin_lock_irqsave(&ifs->state_lock, flags);
 169	bitmap_set(ifs->state, first_blk + blks_per_folio, nr_blks);
 170	spin_unlock_irqrestore(&ifs->state_lock, flags);
 171}
 172
 173static void iomap_set_range_dirty(struct folio *folio, size_t off, size_t len)
 174{
 175	struct iomap_folio_state *ifs = folio->private;
 176
 177	if (ifs)
 178		ifs_set_range_dirty(folio, ifs, off, len);
 179}
 180
 181static struct iomap_folio_state *ifs_alloc(struct inode *inode,
 182		struct folio *folio, unsigned int flags)
 183{
 184	struct iomap_folio_state *ifs = folio->private;
 185	unsigned int nr_blocks = i_blocks_per_folio(inode, folio);
 186	gfp_t gfp;
 187
 188	if (ifs || nr_blocks <= 1)
 189		return ifs;
 190
 191	if (flags & IOMAP_NOWAIT)
 192		gfp = GFP_NOWAIT;
 193	else
 194		gfp = GFP_NOFS | __GFP_NOFAIL;
 195
 196	/*
 197	 * ifs->state tracks two sets of state flags when the
 198	 * filesystem block size is smaller than the folio size.
 199	 * The first state tracks per-block uptodate and the
 200	 * second tracks per-block dirty state.
 201	 */
 202	ifs = kzalloc(struct_size(ifs, state,
 203		      BITS_TO_LONGS(2 * nr_blocks)), gfp);
 204	if (!ifs)
 205		return ifs;
 206
 207	spin_lock_init(&ifs->state_lock);
 208	if (folio_test_uptodate(folio))
 209		bitmap_set(ifs->state, 0, nr_blocks);
 210	if (folio_test_dirty(folio))
 211		bitmap_set(ifs->state, nr_blocks, nr_blocks);
 212	folio_attach_private(folio, ifs);
 213
 214	return ifs;
 215}
 216
 217static void ifs_free(struct folio *folio)
 218{
 219	struct iomap_folio_state *ifs = folio_detach_private(folio);
 
 
 220
 221	if (!ifs)
 222		return;
 223	WARN_ON_ONCE(ifs->read_bytes_pending != 0);
 224	WARN_ON_ONCE(atomic_read(&ifs->write_bytes_pending));
 225	WARN_ON_ONCE(ifs_is_fully_uptodate(folio, ifs) !=
 226			folio_test_uptodate(folio));
 227	kfree(ifs);
 228}
 229
 230/*
 231 * Calculate the range inside the folio that we actually need to read.
 232 */
 233static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
 234		loff_t *pos, loff_t length, size_t *offp, size_t *lenp)
 235{
 236	struct iomap_folio_state *ifs = folio->private;
 237	loff_t orig_pos = *pos;
 238	loff_t isize = i_size_read(inode);
 239	unsigned block_bits = inode->i_blkbits;
 240	unsigned block_size = (1 << block_bits);
 241	size_t poff = offset_in_folio(folio, *pos);
 242	size_t plen = min_t(loff_t, folio_size(folio) - poff, length);
 243	size_t orig_plen = plen;
 244	unsigned first = poff >> block_bits;
 245	unsigned last = (poff + plen - 1) >> block_bits;
 246
 247	/*
 248	 * If the block size is smaller than the page size, we need to check the
 249	 * per-block uptodate status and adjust the offset and length if needed
 250	 * to avoid reading in already uptodate ranges.
 251	 */
 252	if (ifs) {
 253		unsigned int i;
 254
 255		/* move forward for each leading block marked uptodate */
 256		for (i = first; i <= last; i++) {
 257			if (!ifs_block_is_uptodate(ifs, i))
 258				break;
 259			*pos += block_size;
 260			poff += block_size;
 261			plen -= block_size;
 262			first++;
 263		}
 264
 265		/* truncate len if we find any trailing uptodate block(s) */
 266		for ( ; i <= last; i++) {
 267			if (ifs_block_is_uptodate(ifs, i)) {
 268				plen -= (last - i + 1) * block_size;
 269				last = i - 1;
 270				break;
 271			}
 272		}
 273	}
 274
 275	/*
 276	 * If the extent spans the block that contains the i_size, we need to
 277	 * handle both halves separately so that we properly zero data in the
 278	 * page cache for blocks that are entirely outside of i_size.
 279	 */
 280	if (orig_pos <= isize && orig_pos + orig_plen > isize) {
 281		unsigned end = offset_in_folio(folio, isize - 1) >> block_bits;
 282
 283		if (first <= end && last > end)
 284			plen -= (last - end) * block_size;
 285	}
 286
 287	*offp = poff;
 288	*lenp = plen;
 289}
 290
 291static void iomap_finish_folio_read(struct folio *folio, size_t off,
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 292		size_t len, int error)
 293{
 294	struct iomap_folio_state *ifs = folio->private;
 295	bool uptodate = !error;
 296	bool finished = true;
 297
 298	if (ifs) {
 299		unsigned long flags;
 300
 301		spin_lock_irqsave(&ifs->state_lock, flags);
 302		if (!error)
 303			uptodate = ifs_set_range_uptodate(folio, ifs, off, len);
 304		ifs->read_bytes_pending -= len;
 305		finished = !ifs->read_bytes_pending;
 306		spin_unlock_irqrestore(&ifs->state_lock, flags);
 307	}
 308
 309	if (finished)
 310		folio_end_read(folio, uptodate);
 311}
 312
 313static void iomap_read_end_io(struct bio *bio)
 314{
 315	int error = blk_status_to_errno(bio->bi_status);
 316	struct folio_iter fi;
 317
 318	bio_for_each_folio_all(fi, bio)
 319		iomap_finish_folio_read(fi.folio, fi.offset, fi.length, error);
 320	bio_put(bio);
 321}
 322
 323struct iomap_readpage_ctx {
 324	struct folio		*cur_folio;
 325	bool			cur_folio_in_bio;
 326	struct bio		*bio;
 327	struct readahead_control *rac;
 328};
 329
 330/**
 331 * iomap_read_inline_data - copy inline data into the page cache
 332 * @iter: iteration structure
 333 * @folio: folio to copy to
 334 *
 335 * Copy the inline data in @iter into @folio and zero out the rest of the folio.
 336 * Only a single IOMAP_INLINE extent is allowed at the end of each file.
 337 * Returns zero for success to complete the read, or the usual negative errno.
 338 */
 339static int iomap_read_inline_data(const struct iomap_iter *iter,
 340		struct folio *folio)
 341{
 
 342	const struct iomap *iomap = iomap_iter_srcmap(iter);
 343	size_t size = i_size_read(iter->inode) - iomap->offset;
 
 344	size_t offset = offset_in_folio(folio, iomap->offset);
 
 345
 346	if (folio_test_uptodate(folio))
 347		return 0;
 348
 
 
 
 
 
 349	if (WARN_ON_ONCE(size > iomap->length))
 350		return -EIO;
 351	if (offset > 0)
 352		ifs_alloc(iter->inode, folio, iter->flags);
 
 
 353
 354	folio_fill_tail(folio, offset, iomap->inline_data, size);
 355	iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);
 
 
 
 356	return 0;
 357}
 358
 359static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
 360		loff_t pos)
 361{
 362	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 363
 364	return srcmap->type != IOMAP_MAPPED ||
 365		(srcmap->flags & IOMAP_F_NEW) ||
 366		pos >= i_size_read(iter->inode);
 367}
 368
 369static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
 370		struct iomap_readpage_ctx *ctx, loff_t offset)
 371{
 372	const struct iomap *iomap = &iter->iomap;
 373	loff_t pos = iter->pos + offset;
 374	loff_t length = iomap_length(iter) - offset;
 375	struct folio *folio = ctx->cur_folio;
 376	struct iomap_folio_state *ifs;
 377	loff_t orig_pos = pos;
 378	size_t poff, plen;
 379	sector_t sector;
 380
 381	if (iomap->type == IOMAP_INLINE)
 382		return iomap_read_inline_data(iter, folio);
 383
 384	/* zero post-eof blocks as the page may be mapped */
 385	ifs = ifs_alloc(iter->inode, folio, iter->flags);
 386	iomap_adjust_read_range(iter->inode, folio, &pos, length, &poff, &plen);
 387	if (plen == 0)
 388		goto done;
 389
 390	if (iomap_block_needs_zeroing(iter, pos)) {
 391		folio_zero_range(folio, poff, plen);
 392		iomap_set_range_uptodate(folio, poff, plen);
 393		goto done;
 394	}
 395
 396	ctx->cur_folio_in_bio = true;
 397	if (ifs) {
 398		spin_lock_irq(&ifs->state_lock);
 399		ifs->read_bytes_pending += plen;
 400		spin_unlock_irq(&ifs->state_lock);
 401	}
 402
 403	sector = iomap_sector(iomap, pos);
 404	if (!ctx->bio ||
 405	    bio_end_sector(ctx->bio) != sector ||
 406	    !bio_add_folio(ctx->bio, folio, plen, poff)) {
 407		gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
 408		gfp_t orig_gfp = gfp;
 409		unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
 410
 411		if (ctx->bio)
 412			submit_bio(ctx->bio);
 413
 414		if (ctx->rac) /* same as readahead_gfp_mask */
 415			gfp |= __GFP_NORETRY | __GFP_NOWARN;
 416		ctx->bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs),
 417				     REQ_OP_READ, gfp);
 418		/*
 419		 * If the bio_alloc fails, try it again for a single page to
 420		 * avoid having to deal with partial page reads.  This emulates
 421		 * what do_mpage_read_folio does.
 422		 */
 423		if (!ctx->bio) {
 424			ctx->bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ,
 425					     orig_gfp);
 426		}
 427		if (ctx->rac)
 428			ctx->bio->bi_opf |= REQ_RAHEAD;
 429		ctx->bio->bi_iter.bi_sector = sector;
 430		ctx->bio->bi_end_io = iomap_read_end_io;
 431		bio_add_folio_nofail(ctx->bio, folio, plen, poff);
 432	}
 433
 434done:
 435	/*
 436	 * Move the caller beyond our range so that it keeps making progress.
 437	 * For that, we have to include any leading non-uptodate ranges, but
 438	 * we can skip trailing ones as they will be handled in the next
 439	 * iteration.
 440	 */
 441	return pos - orig_pos + plen;
 442}
 443
 444static loff_t iomap_read_folio_iter(const struct iomap_iter *iter,
 445		struct iomap_readpage_ctx *ctx)
 446{
 447	struct folio *folio = ctx->cur_folio;
 448	size_t offset = offset_in_folio(folio, iter->pos);
 449	loff_t length = min_t(loff_t, folio_size(folio) - offset,
 450			      iomap_length(iter));
 451	loff_t done, ret;
 452
 453	for (done = 0; done < length; done += ret) {
 454		ret = iomap_readpage_iter(iter, ctx, done);
 455		if (ret <= 0)
 456			return ret;
 457	}
 458
 459	return done;
 460}
 461
 462int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
 463{
 464	struct iomap_iter iter = {
 465		.inode		= folio->mapping->host,
 466		.pos		= folio_pos(folio),
 467		.len		= folio_size(folio),
 468	};
 469	struct iomap_readpage_ctx ctx = {
 470		.cur_folio	= folio,
 471	};
 472	int ret;
 473
 474	trace_iomap_readpage(iter.inode, 1);
 475
 476	while ((ret = iomap_iter(&iter, ops)) > 0)
 477		iter.processed = iomap_read_folio_iter(&iter, &ctx);
 
 
 
 478
 479	if (ctx.bio) {
 480		submit_bio(ctx.bio);
 481		WARN_ON_ONCE(!ctx.cur_folio_in_bio);
 482	} else {
 483		WARN_ON_ONCE(ctx.cur_folio_in_bio);
 484		folio_unlock(folio);
 485	}
 486
 487	/*
 488	 * Just like mpage_readahead and block_read_full_folio, we always
 489	 * return 0 and just set the folio error flag on errors.  This
 490	 * should be cleaned up throughout the stack eventually.
 491	 */
 492	return 0;
 493}
 494EXPORT_SYMBOL_GPL(iomap_read_folio);
 495
 496static loff_t iomap_readahead_iter(const struct iomap_iter *iter,
 497		struct iomap_readpage_ctx *ctx)
 498{
 499	loff_t length = iomap_length(iter);
 500	loff_t done, ret;
 501
 502	for (done = 0; done < length; done += ret) {
 503		if (ctx->cur_folio &&
 504		    offset_in_folio(ctx->cur_folio, iter->pos + done) == 0) {
 505			if (!ctx->cur_folio_in_bio)
 506				folio_unlock(ctx->cur_folio);
 507			ctx->cur_folio = NULL;
 508		}
 509		if (!ctx->cur_folio) {
 510			ctx->cur_folio = readahead_folio(ctx->rac);
 511			ctx->cur_folio_in_bio = false;
 512		}
 513		ret = iomap_readpage_iter(iter, ctx, done);
 514		if (ret <= 0)
 515			return ret;
 516	}
 517
 518	return done;
 519}
 520
 521/**
 522 * iomap_readahead - Attempt to read pages from a file.
 523 * @rac: Describes the pages to be read.
 524 * @ops: The operations vector for the filesystem.
 525 *
 526 * This function is for filesystems to call to implement their readahead
 527 * address_space operation.
 528 *
 529 * Context: The @ops callbacks may submit I/O (eg to read the addresses of
 530 * blocks from disc), and may wait for it.  The caller may be trying to
 531 * access a different page, and so sleeping excessively should be avoided.
 532 * It may allocate memory, but should avoid costly allocations.  This
 533 * function is called with memalloc_nofs set, so allocations will not cause
 534 * the filesystem to be reentered.
 535 */
 536void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
 537{
 538	struct iomap_iter iter = {
 539		.inode	= rac->mapping->host,
 540		.pos	= readahead_pos(rac),
 541		.len	= readahead_length(rac),
 542	};
 543	struct iomap_readpage_ctx ctx = {
 544		.rac	= rac,
 545	};
 546
 547	trace_iomap_readahead(rac->mapping->host, readahead_count(rac));
 548
 549	while (iomap_iter(&iter, ops) > 0)
 550		iter.processed = iomap_readahead_iter(&iter, &ctx);
 551
 552	if (ctx.bio)
 553		submit_bio(ctx.bio);
 554	if (ctx.cur_folio) {
 555		if (!ctx.cur_folio_in_bio)
 556			folio_unlock(ctx.cur_folio);
 557	}
 558}
 559EXPORT_SYMBOL_GPL(iomap_readahead);
 560
 561/*
 562 * iomap_is_partially_uptodate checks whether blocks within a folio are
 563 * uptodate or not.
 564 *
 565 * Returns true if all blocks which correspond to the specified part
 566 * of the folio are uptodate.
 567 */
 568bool iomap_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
 569{
 570	struct iomap_folio_state *ifs = folio->private;
 571	struct inode *inode = folio->mapping->host;
 572	unsigned first, last, i;
 573
 574	if (!ifs)
 575		return false;
 576
 577	/* Caller's range may extend past the end of this folio */
 578	count = min(folio_size(folio) - from, count);
 579
 580	/* First and last blocks in range within folio */
 581	first = from >> inode->i_blkbits;
 582	last = (from + count - 1) >> inode->i_blkbits;
 583
 584	for (i = first; i <= last; i++)
 585		if (!ifs_block_is_uptodate(ifs, i))
 586			return false;
 587	return true;
 588}
 589EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
 590
 591/**
 592 * iomap_get_folio - get a folio reference for writing
 593 * @iter: iteration structure
 594 * @pos: start offset of write
 595 * @len: Suggested size of folio to create.
 596 *
 597 * Returns a locked reference to the folio at @pos, or an error pointer if the
 598 * folio could not be obtained.
 599 */
 600struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len)
 601{
 602	fgf_t fgp = FGP_WRITEBEGIN | FGP_NOFS;
 603
 604	if (iter->flags & IOMAP_NOWAIT)
 605		fgp |= FGP_NOWAIT;
 606	fgp |= fgf_set_order(len);
 607
 608	return __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
 609			fgp, mapping_gfp_mask(iter->inode->i_mapping));
 610}
 611EXPORT_SYMBOL_GPL(iomap_get_folio);
 612
 613bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags)
 614{
 615	trace_iomap_release_folio(folio->mapping->host, folio_pos(folio),
 616			folio_size(folio));
 617
 618	/*
 619	 * If the folio is dirty, we refuse to release our metadata because
 620	 * it may be partially dirty.  Once we track per-block dirty state,
 621	 * we can release the metadata if every block is dirty.
 
 622	 */
 623	if (folio_test_dirty(folio))
 624		return false;
 625	ifs_free(folio);
 626	return true;
 627}
 628EXPORT_SYMBOL_GPL(iomap_release_folio);
 629
 630void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len)
 631{
 632	trace_iomap_invalidate_folio(folio->mapping->host,
 633					folio_pos(folio) + offset, len);
 634
 635	/*
 636	 * If we're invalidating the entire folio, clear the dirty state
 637	 * from it and release it to avoid unnecessary buildup of the LRU.
 638	 */
 639	if (offset == 0 && len == folio_size(folio)) {
 640		WARN_ON_ONCE(folio_test_writeback(folio));
 641		folio_cancel_dirty(folio);
 642		ifs_free(folio);
 
 
 
 
 
 643	}
 644}
 645EXPORT_SYMBOL_GPL(iomap_invalidate_folio);
 646
 647bool iomap_dirty_folio(struct address_space *mapping, struct folio *folio)
 648{
 649	struct inode *inode = mapping->host;
 650	size_t len = folio_size(folio);
 651
 652	ifs_alloc(inode, folio, 0);
 653	iomap_set_range_dirty(folio, 0, len);
 654	return filemap_dirty_folio(mapping, folio);
 655}
 656EXPORT_SYMBOL_GPL(iomap_dirty_folio);
 657
 658static void
 659iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
 660{
 661	loff_t i_size = i_size_read(inode);
 662
 663	/*
 664	 * Only truncate newly allocated pages beyoned EOF, even if the
 665	 * write started inside the existing inode size.
 666	 */
 667	if (pos + len > i_size)
 668		truncate_pagecache_range(inode, max(pos, i_size),
 669					 pos + len - 1);
 670}
 671
 672static int iomap_read_folio_sync(loff_t block_start, struct folio *folio,
 673		size_t poff, size_t plen, const struct iomap *iomap)
 674{
 675	struct bio_vec bvec;
 676	struct bio bio;
 677
 678	bio_init(&bio, iomap->bdev, &bvec, 1, REQ_OP_READ);
 679	bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
 680	bio_add_folio_nofail(&bio, folio, plen, poff);
 681	return submit_bio_wait(&bio);
 682}
 683
 684static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
 685		size_t len, struct folio *folio)
 686{
 687	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 688	struct iomap_folio_state *ifs;
 689	loff_t block_size = i_blocksize(iter->inode);
 690	loff_t block_start = round_down(pos, block_size);
 691	loff_t block_end = round_up(pos + len, block_size);
 692	unsigned int nr_blocks = i_blocks_per_folio(iter->inode, folio);
 693	size_t from = offset_in_folio(folio, pos), to = from + len;
 694	size_t poff, plen;
 695
 696	/*
 697	 * If the write or zeroing completely overlaps the current folio, then
 698	 * entire folio will be dirtied so there is no need for
 699	 * per-block state tracking structures to be attached to this folio.
 700	 * For the unshare case, we must read in the ondisk contents because we
 701	 * are not changing pagecache contents.
 702	 */
 703	if (!(iter->flags & IOMAP_UNSHARE) && pos <= folio_pos(folio) &&
 704	    pos + len >= folio_pos(folio) + folio_size(folio))
 705		return 0;
 
 706
 707	ifs = ifs_alloc(iter->inode, folio, iter->flags);
 708	if ((iter->flags & IOMAP_NOWAIT) && !ifs && nr_blocks > 1)
 709		return -EAGAIN;
 710
 711	if (folio_test_uptodate(folio))
 712		return 0;
 713
 714	do {
 715		iomap_adjust_read_range(iter->inode, folio, &block_start,
 716				block_end - block_start, &poff, &plen);
 717		if (plen == 0)
 718			break;
 719
 720		if (!(iter->flags & IOMAP_UNSHARE) &&
 721		    (from <= poff || from >= poff + plen) &&
 722		    (to <= poff || to >= poff + plen))
 723			continue;
 724
 725		if (iomap_block_needs_zeroing(iter, block_start)) {
 726			if (WARN_ON_ONCE(iter->flags & IOMAP_UNSHARE))
 727				return -EIO;
 728			folio_zero_segments(folio, poff, from, to, poff + plen);
 729		} else {
 730			int status;
 731
 732			if (iter->flags & IOMAP_NOWAIT)
 733				return -EAGAIN;
 734
 735			status = iomap_read_folio_sync(block_start, folio,
 736					poff, plen, srcmap);
 737			if (status)
 738				return status;
 739		}
 740		iomap_set_range_uptodate(folio, poff, plen);
 741	} while ((block_start += plen) < block_end);
 742
 743	return 0;
 744}
 745
 746static struct folio *__iomap_get_folio(struct iomap_iter *iter, loff_t pos,
 747		size_t len)
 748{
 749	const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
 750
 751	if (folio_ops && folio_ops->get_folio)
 752		return folio_ops->get_folio(iter, pos, len);
 753	else
 754		return iomap_get_folio(iter, pos, len);
 755}
 756
 757static void __iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret,
 758		struct folio *folio)
 759{
 760	const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
 761
 762	if (folio_ops && folio_ops->put_folio) {
 763		folio_ops->put_folio(iter->inode, pos, ret, folio);
 764	} else {
 765		folio_unlock(folio);
 766		folio_put(folio);
 767	}
 768}
 769
 770static int iomap_write_begin_inline(const struct iomap_iter *iter,
 771		struct folio *folio)
 772{
 773	/* needs more work for the tailpacking case; disable for now */
 774	if (WARN_ON_ONCE(iomap_iter_srcmap(iter)->offset != 0))
 775		return -EIO;
 776	return iomap_read_inline_data(iter, folio);
 777}
 778
 779static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
 780		size_t len, struct folio **foliop)
 781{
 782	const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
 783	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 784	struct folio *folio;
 
 785	int status = 0;
 786
 
 
 
 787	BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
 788	if (srcmap != &iter->iomap)
 789		BUG_ON(pos + len > srcmap->offset + srcmap->length);
 790
 791	if (fatal_signal_pending(current))
 792		return -EINTR;
 793
 794	if (!mapping_large_folio_support(iter->inode->i_mapping))
 795		len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
 796
 797	folio = __iomap_get_folio(iter, pos, len);
 798	if (IS_ERR(folio))
 799		return PTR_ERR(folio);
 
 
 
 
 
 
 
 
 
 800
 801	/*
 802	 * Now we have a locked folio, before we do anything with it we need to
 803	 * check that the iomap we have cached is not stale. The inode extent
 804	 * mapping can change due to concurrent IO in flight (e.g.
 805	 * IOMAP_UNWRITTEN state can change and memory reclaim could have
 806	 * reclaimed a previously partially written page at this index after IO
 807	 * completion before this write reaches this file offset) and hence we
 808	 * could do the wrong thing here (zero a page range incorrectly or fail
 809	 * to zero) and corrupt data.
 810	 */
 811	if (folio_ops && folio_ops->iomap_valid) {
 812		bool iomap_valid = folio_ops->iomap_valid(iter->inode,
 813							 &iter->iomap);
 814		if (!iomap_valid) {
 815			iter->iomap.flags |= IOMAP_F_STALE;
 816			status = 0;
 817			goto out_unlock;
 818		}
 819	}
 820
 821	if (pos + len > folio_pos(folio) + folio_size(folio))
 822		len = folio_pos(folio) + folio_size(folio) - pos;
 823
 824	if (srcmap->type == IOMAP_INLINE)
 825		status = iomap_write_begin_inline(iter, folio);
 826	else if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
 827		status = __block_write_begin_int(folio, pos, len, NULL, srcmap);
 828	else
 829		status = __iomap_write_begin(iter, pos, len, folio);
 830
 831	if (unlikely(status))
 832		goto out_unlock;
 833
 834	*foliop = folio;
 835	return 0;
 836
 837out_unlock:
 838	__iomap_put_folio(iter, pos, 0, folio);
 
 
 839
 
 
 
 840	return status;
 841}
 842
 843static bool __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
 844		size_t copied, struct folio *folio)
 845{
 
 846	flush_dcache_folio(folio);
 847
 848	/*
 849	 * The blocks that were entirely written will now be uptodate, so we
 850	 * don't have to worry about a read_folio reading them and overwriting a
 851	 * partial write.  However, if we've encountered a short write and only
 852	 * partially written into a block, it will not be marked uptodate, so a
 853	 * read_folio might come in and destroy our partial write.
 854	 *
 855	 * Do the simplest thing and just treat any short write to a
 856	 * non-uptodate page as a zero-length write, and force the caller to
 857	 * redo the whole thing.
 858	 */
 859	if (unlikely(copied < len && !folio_test_uptodate(folio)))
 860		return false;
 861	iomap_set_range_uptodate(folio, offset_in_folio(folio, pos), len);
 862	iomap_set_range_dirty(folio, offset_in_folio(folio, pos), copied);
 863	filemap_dirty_folio(inode->i_mapping, folio);
 864	return true;
 865}
 866
 867static void iomap_write_end_inline(const struct iomap_iter *iter,
 868		struct folio *folio, loff_t pos, size_t copied)
 869{
 870	const struct iomap *iomap = &iter->iomap;
 871	void *addr;
 872
 873	WARN_ON_ONCE(!folio_test_uptodate(folio));
 874	BUG_ON(!iomap_inline_data_valid(iomap));
 875
 876	flush_dcache_folio(folio);
 877	addr = kmap_local_folio(folio, pos);
 878	memcpy(iomap_inline_data(iomap, pos), addr, copied);
 879	kunmap_local(addr);
 880
 881	mark_inode_dirty(iter->inode);
 
 882}
 883
 884/*
 885 * Returns true if all copied bytes have been written to the pagecache,
 886 * otherwise return false.
 887 */
 888static bool iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
 889		size_t copied, struct folio *folio)
 890{
 
 891	const struct iomap *srcmap = iomap_iter_srcmap(iter);
 
 
 892
 893	if (srcmap->type == IOMAP_INLINE) {
 894		iomap_write_end_inline(iter, folio, pos, copied);
 895		return true;
 
 
 
 
 896	}
 897
 898	if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
 899		size_t bh_written;
 900
 901		bh_written = block_write_end(NULL, iter->inode->i_mapping, pos,
 902					len, copied, folio, NULL);
 903		WARN_ON_ONCE(bh_written != copied && bh_written != 0);
 904		return bh_written == copied;
 
 905	}
 
 906
 907	return __iomap_write_end(iter->inode, pos, len, copied, folio);
 
 
 
 
 
 
 
 
 908}
 909
 910static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 911{
 912	loff_t length = iomap_length(iter);
 913	loff_t pos = iter->pos;
 914	ssize_t total_written = 0;
 915	long status = 0;
 916	struct address_space *mapping = iter->inode->i_mapping;
 917	size_t chunk = mapping_max_folio_size(mapping);
 918	unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0;
 919
 920	do {
 921		struct folio *folio;
 922		loff_t old_size;
 923		size_t offset;		/* Offset into folio */
 924		size_t bytes;		/* Bytes to write to folio */
 925		size_t copied;		/* Bytes copied from user */
 926		size_t written;		/* Bytes have been written */
 927
 928		bytes = iov_iter_count(i);
 929retry:
 930		offset = pos & (chunk - 1);
 931		bytes = min(chunk - offset, bytes);
 932		status = balance_dirty_pages_ratelimited_flags(mapping,
 933							       bdp_flags);
 934		if (unlikely(status))
 935			break;
 936
 937		if (bytes > length)
 938			bytes = length;
 939
 940		/*
 941		 * Bring in the user page that we'll copy from _first_.
 942		 * Otherwise there's a nasty deadlock on copying from the
 943		 * same page as we're writing to, without it being marked
 944		 * up-to-date.
 945		 *
 946		 * For async buffered writes the assumption is that the user
 947		 * page has already been faulted in. This can be optimized by
 948		 * faulting the user page.
 949		 */
 950		if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) {
 951			status = -EFAULT;
 952			break;
 953		}
 954
 955		status = iomap_write_begin(iter, pos, bytes, &folio);
 956		if (unlikely(status)) {
 957			iomap_write_failed(iter->inode, pos, bytes);
 958			break;
 959		}
 960		if (iter->iomap.flags & IOMAP_F_STALE)
 961			break;
 962
 963		offset = offset_in_folio(folio, pos);
 964		if (bytes > folio_size(folio) - offset)
 965			bytes = folio_size(folio) - offset;
 966
 967		if (mapping_writably_mapped(mapping))
 968			flush_dcache_folio(folio);
 969
 970		copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
 971		written = iomap_write_end(iter, pos, bytes, copied, folio) ?
 972			  copied : 0;
 973
 974		/*
 975		 * Update the in-memory inode size after copying the data into
 976		 * the page cache.  It's up to the file system to write the
 977		 * updated size to disk, preferably after I/O completion so that
 978		 * no stale data is exposed.  Only once that's done can we
 979		 * unlock and release the folio.
 980		 */
 981		old_size = iter->inode->i_size;
 982		if (pos + written > old_size) {
 983			i_size_write(iter->inode, pos + written);
 984			iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
 985		}
 986		__iomap_put_folio(iter, pos, written, folio);
 987
 988		if (old_size < pos)
 989			pagecache_isize_extended(iter->inode, old_size, pos);
 990
 991		cond_resched();
 992		if (unlikely(written == 0)) {
 993			/*
 994			 * A short copy made iomap_write_end() reject the
 995			 * thing entirely.  Might be memory poisoning
 996			 * halfway through, might be a race with munmap,
 997			 * might be severe memory pressure.
 998			 */
 999			iomap_write_failed(iter->inode, pos, bytes);
1000			iov_iter_revert(i, copied);
1001
1002			if (chunk > PAGE_SIZE)
1003				chunk /= 2;
1004			if (copied) {
1005				bytes = copied;
1006				goto retry;
1007			}
1008		} else {
1009			pos += written;
1010			total_written += written;
1011			length -= written;
1012		}
 
 
 
1013	} while (iov_iter_count(i) && length);
1014
1015	if (status == -EAGAIN) {
1016		iov_iter_revert(i, total_written);
1017		return -EAGAIN;
1018	}
1019	return total_written ? total_written : status;
1020}
1021
1022ssize_t
1023iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
1024		const struct iomap_ops *ops, void *private)
1025{
1026	struct iomap_iter iter = {
1027		.inode		= iocb->ki_filp->f_mapping->host,
1028		.pos		= iocb->ki_pos,
1029		.len		= iov_iter_count(i),
1030		.flags		= IOMAP_WRITE,
1031		.private	= private,
1032	};
1033	ssize_t ret;
1034
1035	if (iocb->ki_flags & IOCB_NOWAIT)
1036		iter.flags |= IOMAP_NOWAIT;
1037
1038	while ((ret = iomap_iter(&iter, ops)) > 0)
1039		iter.processed = iomap_write_iter(&iter, i);
1040
1041	if (unlikely(iter.pos == iocb->ki_pos))
1042		return ret;
1043	ret = iter.pos - iocb->ki_pos;
1044	iocb->ki_pos = iter.pos;
1045	return ret;
1046}
1047EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
1048
1049static void iomap_write_delalloc_ifs_punch(struct inode *inode,
1050		struct folio *folio, loff_t start_byte, loff_t end_byte,
1051		struct iomap *iomap, iomap_punch_t punch)
1052{
1053	unsigned int first_blk, last_blk, i;
1054	loff_t last_byte;
1055	u8 blkbits = inode->i_blkbits;
1056	struct iomap_folio_state *ifs;
1057
1058	/*
1059	 * When we have per-block dirty tracking, there can be
1060	 * blocks within a folio which are marked uptodate
1061	 * but not dirty. In that case it is necessary to punch
1062	 * out such blocks to avoid leaking any delalloc blocks.
1063	 */
1064	ifs = folio->private;
1065	if (!ifs)
1066		return;
1067
1068	last_byte = min_t(loff_t, end_byte - 1,
1069			folio_pos(folio) + folio_size(folio) - 1);
1070	first_blk = offset_in_folio(folio, start_byte) >> blkbits;
1071	last_blk = offset_in_folio(folio, last_byte) >> blkbits;
1072	for (i = first_blk; i <= last_blk; i++) {
1073		if (!ifs_block_is_dirty(folio, ifs, i))
1074			punch(inode, folio_pos(folio) + (i << blkbits),
1075				    1 << blkbits, iomap);
1076	}
1077}
1078
1079static void iomap_write_delalloc_punch(struct inode *inode, struct folio *folio,
1080		loff_t *punch_start_byte, loff_t start_byte, loff_t end_byte,
1081		struct iomap *iomap, iomap_punch_t punch)
1082{
1083	if (!folio_test_dirty(folio))
1084		return;
1085
1086	/* if dirty, punch up to offset */
1087	if (start_byte > *punch_start_byte) {
1088		punch(inode, *punch_start_byte, start_byte - *punch_start_byte,
1089				iomap);
1090	}
1091
1092	/* Punch non-dirty blocks within folio */
1093	iomap_write_delalloc_ifs_punch(inode, folio, start_byte, end_byte,
1094			iomap, punch);
1095
1096	/*
1097	 * Make sure the next punch start is correctly bound to
1098	 * the end of this data range, not the end of the folio.
1099	 */
1100	*punch_start_byte = min_t(loff_t, end_byte,
1101				folio_pos(folio) + folio_size(folio));
1102}
1103
1104/*
1105 * Scan the data range passed to us for dirty page cache folios. If we find a
1106 * dirty folio, punch out the preceding range and update the offset from which
1107 * the next punch will start from.
1108 *
1109 * We can punch out storage reservations under clean pages because they either
1110 * contain data that has been written back - in which case the delalloc punch
1111 * over that range is a no-op - or they have been read faults in which case they
1112 * contain zeroes and we can remove the delalloc backing range and any new
1113 * writes to those pages will do the normal hole filling operation...
1114 *
1115 * This makes the logic simple: we only need to keep the delalloc extents only
1116 * over the dirty ranges of the page cache.
1117 *
1118 * This function uses [start_byte, end_byte) intervals (i.e. open ended) to
1119 * simplify range iterations.
1120 */
1121static void iomap_write_delalloc_scan(struct inode *inode,
1122		loff_t *punch_start_byte, loff_t start_byte, loff_t end_byte,
1123		struct iomap *iomap, iomap_punch_t punch)
1124{
1125	while (start_byte < end_byte) {
1126		struct folio	*folio;
1127
1128		/* grab locked page */
1129		folio = filemap_lock_folio(inode->i_mapping,
1130				start_byte >> PAGE_SHIFT);
1131		if (IS_ERR(folio)) {
1132			start_byte = ALIGN_DOWN(start_byte, PAGE_SIZE) +
1133					PAGE_SIZE;
1134			continue;
1135		}
1136
1137		iomap_write_delalloc_punch(inode, folio, punch_start_byte,
1138				start_byte, end_byte, iomap, punch);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1139
1140		/* move offset to start of next folio in range */
1141		start_byte = folio_pos(folio) + folio_size(folio);
1142		folio_unlock(folio);
1143		folio_put(folio);
1144	}
 
1145}
1146
1147/*
1148 * When a short write occurs, the filesystem might need to use ->iomap_end
1149 * to remove space reservations created in ->iomap_begin.
1150 *
1151 * For filesystems that use delayed allocation, there can be dirty pages over
1152 * the delalloc extent outside the range of a short write but still within the
1153 * delalloc extent allocated for this iomap if the write raced with page
1154 * faults.
1155 *
1156 * Punch out all the delalloc blocks in the range given except for those that
1157 * have dirty data still pending in the page cache - those are going to be
1158 * written and so must still retain the delalloc backing for writeback.
1159 *
1160 * The punch() callback *must* only punch delalloc extents in the range passed
1161 * to it. It must skip over all other types of extents in the range and leave
1162 * them completely unchanged. It must do this punch atomically with respect to
1163 * other extent modifications.
1164 *
1165 * The punch() callback may be called with a folio locked to prevent writeback
1166 * extent allocation racing at the edge of the range we are currently punching.
1167 * The locked folio may or may not cover the range being punched, so it is not
1168 * safe for the punch() callback to lock folios itself.
1169 *
1170 * Lock order is:
1171 *
1172 * inode->i_rwsem (shared or exclusive)
1173 *   inode->i_mapping->invalidate_lock (exclusive)
1174 *     folio_lock()
1175 *       ->punch
1176 *         internal filesystem allocation lock
1177 *
1178 * As we are scanning the page cache for data, we don't need to reimplement the
1179 * wheel - mapping_seek_hole_data() does exactly what we need to identify the
1180 * start and end of data ranges correctly even for sub-folio block sizes. This
1181 * byte range based iteration is especially convenient because it means we
1182 * don't have to care about variable size folios, nor where the start or end of
1183 * the data range lies within a folio, if they lie within the same folio or even
1184 * if there are multiple discontiguous data ranges within the folio.
1185 *
1186 * It should be noted that mapping_seek_hole_data() is not aware of EOF, and so
1187 * can return data ranges that exist in the cache beyond EOF. e.g. a page fault
1188 * spanning EOF will initialise the post-EOF data to zeroes and mark it up to
1189 * date. A write page fault can then mark it dirty. If we then fail a write()
1190 * beyond EOF into that up to date cached range, we allocate a delalloc block
1191 * beyond EOF and then have to punch it out. Because the range is up to date,
1192 * mapping_seek_hole_data() will return it, and we will skip the punch because
1193 * the folio is dirty. THis is incorrect - we always need to punch out delalloc
1194 * beyond EOF in this case as writeback will never write back and covert that
1195 * delalloc block beyond EOF. Hence we limit the cached data scan range to EOF,
1196 * resulting in always punching out the range from the EOF to the end of the
1197 * range the iomap spans.
1198 *
1199 * Intervals are of the form [start_byte, end_byte) (i.e. open ended) because it
1200 * matches the intervals returned by mapping_seek_hole_data(). i.e. SEEK_DATA
1201 * returns the start of a data range (start_byte), and SEEK_HOLE(start_byte)
1202 * returns the end of the data range (data_end). Using closed intervals would
1203 * require sprinkling this code with magic "+ 1" and "- 1" arithmetic and expose
1204 * the code to subtle off-by-one bugs....
1205 */
1206void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
1207		loff_t end_byte, unsigned flags, struct iomap *iomap,
1208		iomap_punch_t punch)
1209{
1210	loff_t punch_start_byte = start_byte;
1211	loff_t scan_end_byte = min(i_size_read(inode), end_byte);
 
1212
1213	/*
1214	 * The caller must hold invalidate_lock to avoid races with page faults
1215	 * re-instantiating folios and dirtying them via ->page_mkwrite whilst
1216	 * we walk the cache and perform delalloc extent removal.  Failing to do
1217	 * this can leave dirty pages with no space reservation in the cache.
1218	 */
1219	lockdep_assert_held_write(&inode->i_mapping->invalidate_lock);
1220
1221	while (start_byte < scan_end_byte) {
1222		loff_t		data_end;
1223
1224		start_byte = mapping_seek_hole_data(inode->i_mapping,
1225				start_byte, scan_end_byte, SEEK_DATA);
1226		/*
1227		 * If there is no more data to scan, all that is left is to
1228		 * punch out the remaining range.
1229		 *
1230		 * Note that mapping_seek_hole_data is only supposed to return
1231		 * either an offset or -ENXIO, so WARN on any other error as
1232		 * that would be an API change without updating the callers.
1233		 */
1234		if (start_byte == -ENXIO || start_byte == scan_end_byte)
1235			break;
1236		if (WARN_ON_ONCE(start_byte < 0))
1237			return;
 
 
1238		WARN_ON_ONCE(start_byte < punch_start_byte);
1239		WARN_ON_ONCE(start_byte > scan_end_byte);
1240
1241		/*
1242		 * We find the end of this contiguous cached data range by
1243		 * seeking from start_byte to the beginning of the next hole.
1244		 */
1245		data_end = mapping_seek_hole_data(inode->i_mapping, start_byte,
1246				scan_end_byte, SEEK_HOLE);
1247		if (WARN_ON_ONCE(data_end < 0))
1248			return;
1249
1250		/*
1251		 * If we race with post-direct I/O invalidation of the page cache,
1252		 * there might be no data left at start_byte.
1253		 */
1254		if (data_end == start_byte)
1255			continue;
1256
1257		WARN_ON_ONCE(data_end < start_byte);
1258		WARN_ON_ONCE(data_end > scan_end_byte);
1259
1260		iomap_write_delalloc_scan(inode, &punch_start_byte, start_byte,
1261				data_end, iomap, punch);
 
 
1262
1263		/* The next data search starts at the end of this one. */
1264		start_byte = data_end;
1265	}
1266
1267	if (punch_start_byte < end_byte)
1268		punch(inode, punch_start_byte, end_byte - punch_start_byte,
1269				iomap);
 
 
 
1270}
1271EXPORT_SYMBOL_GPL(iomap_write_delalloc_release);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1272
1273static loff_t iomap_unshare_iter(struct iomap_iter *iter)
1274{
1275	struct iomap *iomap = &iter->iomap;
 
1276	loff_t pos = iter->pos;
1277	loff_t length = iomap_length(iter);
 
1278	loff_t written = 0;
1279
1280	if (!iomap_want_unshare_iter(iter))
 
 
 
 
1281		return length;
1282
1283	do {
 
 
1284		struct folio *folio;
1285		int status;
1286		size_t offset;
1287		size_t bytes = min_t(u64, SIZE_MAX, length);
1288		bool ret;
1289
1290		status = iomap_write_begin(iter, pos, bytes, &folio);
1291		if (unlikely(status))
1292			return status;
1293		if (iomap->flags & IOMAP_F_STALE)
1294			break;
1295
1296		offset = offset_in_folio(folio, pos);
1297		if (bytes > folio_size(folio) - offset)
1298			bytes = folio_size(folio) - offset;
1299
1300		ret = iomap_write_end(iter, pos, bytes, bytes, folio);
1301		__iomap_put_folio(iter, pos, bytes, folio);
1302		if (WARN_ON_ONCE(!ret))
1303			return -EIO;
1304
1305		cond_resched();
1306
1307		pos += bytes;
1308		written += bytes;
1309		length -= bytes;
1310
1311		balance_dirty_pages_ratelimited(iter->inode->i_mapping);
1312	} while (length > 0);
1313
1314	return written;
1315}
1316
1317int
1318iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
1319		const struct iomap_ops *ops)
1320{
1321	struct iomap_iter iter = {
1322		.inode		= inode,
1323		.pos		= pos,
 
1324		.flags		= IOMAP_WRITE | IOMAP_UNSHARE,
1325	};
1326	loff_t size = i_size_read(inode);
1327	int ret;
1328
1329	if (pos < 0 || pos >= size)
1330		return 0;
1331
1332	iter.len = min(len, size - pos);
1333	while ((ret = iomap_iter(&iter, ops)) > 0)
1334		iter.processed = iomap_unshare_iter(&iter);
1335	return ret;
1336}
1337EXPORT_SYMBOL_GPL(iomap_file_unshare);
1338
1339/*
1340 * Flush the remaining range of the iter and mark the current mapping stale.
1341 * This is used when zero range sees an unwritten mapping that may have had
1342 * dirty pagecache over it.
1343 */
1344static inline int iomap_zero_iter_flush_and_stale(struct iomap_iter *i)
1345{
1346	struct address_space *mapping = i->inode->i_mapping;
1347	loff_t end = i->pos + i->len - 1;
1348
1349	i->iomap.flags |= IOMAP_F_STALE;
1350	return filemap_write_and_wait_range(mapping, i->pos, end);
1351}
1352
1353static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
1354{
 
1355	loff_t pos = iter->pos;
1356	loff_t length = iomap_length(iter);
1357	loff_t written = 0;
1358
 
 
 
 
1359	do {
1360		struct folio *folio;
1361		int status;
1362		size_t offset;
1363		size_t bytes = min_t(u64, SIZE_MAX, length);
1364		bool ret;
1365
1366		status = iomap_write_begin(iter, pos, bytes, &folio);
1367		if (status)
1368			return status;
1369		if (iter->iomap.flags & IOMAP_F_STALE)
1370			break;
1371
1372		/* warn about zeroing folios beyond eof that won't write back */
1373		WARN_ON_ONCE(folio_pos(folio) > iter->inode->i_size);
1374		offset = offset_in_folio(folio, pos);
1375		if (bytes > folio_size(folio) - offset)
1376			bytes = folio_size(folio) - offset;
1377
1378		folio_zero_range(folio, offset, bytes);
1379		folio_mark_accessed(folio);
1380
1381		ret = iomap_write_end(iter, pos, bytes, bytes, folio);
1382		__iomap_put_folio(iter, pos, bytes, folio);
1383		if (WARN_ON_ONCE(!ret))
1384			return -EIO;
1385
1386		pos += bytes;
1387		length -= bytes;
1388		written += bytes;
1389	} while (length > 0);
1390
1391	if (did_zero)
1392		*did_zero = true;
1393	return written;
1394}
1395
1396int
1397iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
1398		const struct iomap_ops *ops)
1399{
1400	struct iomap_iter iter = {
1401		.inode		= inode,
1402		.pos		= pos,
1403		.len		= len,
1404		.flags		= IOMAP_ZERO,
1405	};
1406	struct address_space *mapping = inode->i_mapping;
1407	unsigned int blocksize = i_blocksize(inode);
1408	unsigned int off = pos & (blocksize - 1);
1409	loff_t plen = min_t(loff_t, len, blocksize - off);
1410	int ret;
1411	bool range_dirty;
1412
1413	/*
1414	 * Zero range can skip mappings that are zero on disk so long as
1415	 * pagecache is clean. If pagecache was dirty prior to zero range, the
1416	 * mapping converts on writeback completion and so must be zeroed.
1417	 *
1418	 * The simplest way to deal with this across a range is to flush
1419	 * pagecache and process the updated mappings. To avoid excessive
1420	 * flushing on partial eof zeroing, special case it to zero the
1421	 * unaligned start portion if already dirty in pagecache.
1422	 */
1423	if (off &&
1424	    filemap_range_needs_writeback(mapping, pos, pos + plen - 1)) {
1425		iter.len = plen;
1426		while ((ret = iomap_iter(&iter, ops)) > 0)
1427			iter.processed = iomap_zero_iter(&iter, did_zero);
1428
1429		iter.len = len - (iter.pos - pos);
1430		if (ret || !iter.len)
1431			return ret;
1432	}
1433
1434	/*
1435	 * To avoid an unconditional flush, check pagecache state and only flush
1436	 * if dirty and the fs returns a mapping that might convert on
1437	 * writeback.
1438	 */
1439	range_dirty = filemap_range_needs_writeback(inode->i_mapping,
1440					iter.pos, iter.pos + iter.len - 1);
1441	while ((ret = iomap_iter(&iter, ops)) > 0) {
1442		const struct iomap *srcmap = iomap_iter_srcmap(&iter);
1443
1444		if (srcmap->type == IOMAP_HOLE ||
1445		    srcmap->type == IOMAP_UNWRITTEN) {
1446			loff_t proc = iomap_length(&iter);
1447
1448			if (range_dirty) {
1449				range_dirty = false;
1450				proc = iomap_zero_iter_flush_and_stale(&iter);
1451			}
1452			iter.processed = proc;
1453			continue;
1454		}
1455
 
1456		iter.processed = iomap_zero_iter(&iter, did_zero);
1457	}
1458	return ret;
1459}
1460EXPORT_SYMBOL_GPL(iomap_zero_range);
1461
1462int
1463iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
1464		const struct iomap_ops *ops)
1465{
1466	unsigned int blocksize = i_blocksize(inode);
1467	unsigned int off = pos & (blocksize - 1);
1468
1469	/* Block boundary? Nothing to do */
1470	if (!off)
1471		return 0;
1472	return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
1473}
1474EXPORT_SYMBOL_GPL(iomap_truncate_page);
1475
1476static loff_t iomap_folio_mkwrite_iter(struct iomap_iter *iter,
1477		struct folio *folio)
1478{
1479	loff_t length = iomap_length(iter);
1480	int ret;
1481
1482	if (iter->iomap.flags & IOMAP_F_BUFFER_HEAD) {
1483		ret = __block_write_begin_int(folio, iter->pos, length, NULL,
1484					      &iter->iomap);
1485		if (ret)
1486			return ret;
1487		block_commit_write(&folio->page, 0, length);
1488	} else {
1489		WARN_ON_ONCE(!folio_test_uptodate(folio));
1490		folio_mark_dirty(folio);
1491	}
1492
1493	return length;
1494}
1495
1496vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
1497{
1498	struct iomap_iter iter = {
1499		.inode		= file_inode(vmf->vma->vm_file),
1500		.flags		= IOMAP_WRITE | IOMAP_FAULT,
1501	};
1502	struct folio *folio = page_folio(vmf->page);
1503	ssize_t ret;
1504
1505	folio_lock(folio);
1506	ret = folio_mkwrite_check_truncate(folio, iter.inode);
1507	if (ret < 0)
1508		goto out_unlock;
1509	iter.pos = folio_pos(folio);
1510	iter.len = ret;
1511	while ((ret = iomap_iter(&iter, ops)) > 0)
1512		iter.processed = iomap_folio_mkwrite_iter(&iter, folio);
1513
1514	if (ret < 0)
1515		goto out_unlock;
1516	folio_wait_stable(folio);
1517	return VM_FAULT_LOCKED;
1518out_unlock:
1519	folio_unlock(folio);
1520	return vmf_fs_error(ret);
1521}
1522EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
1523
1524static void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
1525		size_t len)
1526{
1527	struct iomap_folio_state *ifs = folio->private;
1528
1529	WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !ifs);
1530	WARN_ON_ONCE(ifs && atomic_read(&ifs->write_bytes_pending) <= 0);
 
 
1531
1532	if (!ifs || atomic_sub_and_test(len, &ifs->write_bytes_pending))
 
 
 
1533		folio_end_writeback(folio);
1534}
1535
1536/*
1537 * We're now finished for good with this ioend structure.  Update the page
1538 * state, release holds on bios, and finally free up memory.  Do not use the
1539 * ioend after this.
1540 */
1541static u32
1542iomap_finish_ioend(struct iomap_ioend *ioend, int error)
1543{
1544	struct inode *inode = ioend->io_inode;
1545	struct bio *bio = &ioend->io_bio;
1546	struct folio_iter fi;
 
 
 
1547	u32 folio_count = 0;
1548
1549	if (error) {
1550		mapping_set_error(inode->i_mapping, error);
1551		if (!bio_flagged(bio, BIO_QUIET)) {
1552			pr_err_ratelimited(
1553"%s: writeback error on inode %lu, offset %lld, sector %llu",
1554				inode->i_sb->s_id, inode->i_ino,
1555				ioend->io_offset, ioend->io_sector);
 
 
 
 
 
 
 
 
 
 
1556		}
 
1557	}
 
1558
1559	/* walk all folios in bio, ending page IO on them */
1560	bio_for_each_folio_all(fi, bio) {
1561		iomap_finish_folio_write(inode, fi.folio, fi.length);
1562		folio_count++;
1563	}
1564
1565	bio_put(bio);	/* frees the ioend */
1566	return folio_count;
1567}
1568
1569/*
1570 * Ioend completion routine for merged bios. This can only be called from task
1571 * contexts as merged ioends can be of unbound length. Hence we have to break up
1572 * the writeback completions into manageable chunks to avoid long scheduler
1573 * holdoffs. We aim to keep scheduler holdoffs down below 10ms so that we get
1574 * good batch processing throughput without creating adverse scheduler latency
1575 * conditions.
1576 */
1577void
1578iomap_finish_ioends(struct iomap_ioend *ioend, int error)
1579{
1580	struct list_head tmp;
1581	u32 completions;
1582
1583	might_sleep();
1584
1585	list_replace_init(&ioend->io_list, &tmp);
1586	completions = iomap_finish_ioend(ioend, error);
1587
1588	while (!list_empty(&tmp)) {
1589		if (completions > IOEND_BATCH_SIZE * 8) {
1590			cond_resched();
1591			completions = 0;
1592		}
1593		ioend = list_first_entry(&tmp, struct iomap_ioend, io_list);
1594		list_del_init(&ioend->io_list);
1595		completions += iomap_finish_ioend(ioend, error);
1596	}
1597}
1598EXPORT_SYMBOL_GPL(iomap_finish_ioends);
1599
1600/*
1601 * We can merge two adjacent ioends if they have the same set of work to do.
1602 */
1603static bool
1604iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
1605{
1606	if (ioend->io_bio.bi_status != next->io_bio.bi_status)
1607		return false;
1608	if (next->io_flags & IOMAP_F_BOUNDARY)
1609		return false;
1610	if ((ioend->io_flags & IOMAP_F_SHARED) ^
1611	    (next->io_flags & IOMAP_F_SHARED))
1612		return false;
1613	if ((ioend->io_type == IOMAP_UNWRITTEN) ^
1614	    (next->io_type == IOMAP_UNWRITTEN))
1615		return false;
1616	if (ioend->io_offset + ioend->io_size != next->io_offset)
1617		return false;
1618	/*
1619	 * Do not merge physically discontiguous ioends. The filesystem
1620	 * completion functions will have to iterate the physical
1621	 * discontiguities even if we merge the ioends at a logical level, so
1622	 * we don't gain anything by merging physical discontiguities here.
1623	 *
1624	 * We cannot use bio->bi_iter.bi_sector here as it is modified during
1625	 * submission so does not point to the start sector of the bio at
1626	 * completion.
1627	 */
1628	if (ioend->io_sector + (ioend->io_size >> 9) != next->io_sector)
1629		return false;
1630	return true;
1631}
1632
1633void
1634iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends)
1635{
1636	struct iomap_ioend *next;
1637
1638	INIT_LIST_HEAD(&ioend->io_list);
1639
1640	while ((next = list_first_entry_or_null(more_ioends, struct iomap_ioend,
1641			io_list))) {
1642		if (!iomap_ioend_can_merge(ioend, next))
1643			break;
1644		list_move_tail(&next->io_list, &ioend->io_list);
1645		ioend->io_size += next->io_size;
1646	}
1647}
1648EXPORT_SYMBOL_GPL(iomap_ioend_try_merge);
1649
1650static int
1651iomap_ioend_compare(void *priv, const struct list_head *a,
1652		const struct list_head *b)
1653{
1654	struct iomap_ioend *ia = container_of(a, struct iomap_ioend, io_list);
1655	struct iomap_ioend *ib = container_of(b, struct iomap_ioend, io_list);
1656
1657	if (ia->io_offset < ib->io_offset)
1658		return -1;
1659	if (ia->io_offset > ib->io_offset)
1660		return 1;
1661	return 0;
1662}
1663
1664void
1665iomap_sort_ioends(struct list_head *ioend_list)
1666{
1667	list_sort(NULL, ioend_list, iomap_ioend_compare);
1668}
1669EXPORT_SYMBOL_GPL(iomap_sort_ioends);
1670
1671static void iomap_writepage_end_bio(struct bio *bio)
1672{
1673	iomap_finish_ioend(iomap_ioend_from_bio(bio),
1674			blk_status_to_errno(bio->bi_status));
 
1675}
1676
1677/*
1678 * Submit the final bio for an ioend.
1679 *
1680 * If @error is non-zero, it means that we have a situation where some part of
1681 * the submission process has failed after we've marked pages for writeback.
1682 * We cannot cancel ioend directly in that case, so call the bio end I/O handler
1683 * with the error status here to run the normal I/O completion handler to clear
1684 * the writeback bit and let the file system proess the errors.
1685 */
1686static int iomap_submit_ioend(struct iomap_writepage_ctx *wpc, int error)
 
 
1687{
1688	if (!wpc->ioend)
1689		return error;
1690
1691	/*
1692	 * Let the file systems prepare the I/O submission and hook in an I/O
1693	 * comletion handler.  This also needs to happen in case after a
1694	 * failure happened so that the file system end I/O handler gets called
1695	 * to clean up.
1696	 */
1697	if (wpc->ops->prepare_ioend)
1698		error = wpc->ops->prepare_ioend(wpc->ioend, error);
1699
1700	if (error) {
1701		wpc->ioend->io_bio.bi_status = errno_to_blk_status(error);
1702		bio_endio(&wpc->ioend->io_bio);
1703	} else {
1704		submit_bio(&wpc->ioend->io_bio);
 
 
 
 
 
1705	}
1706
1707	wpc->ioend = NULL;
1708	return error;
1709}
1710
1711static struct iomap_ioend *iomap_alloc_ioend(struct iomap_writepage_ctx *wpc,
1712		struct writeback_control *wbc, struct inode *inode, loff_t pos)
 
1713{
1714	struct iomap_ioend *ioend;
1715	struct bio *bio;
1716
1717	bio = bio_alloc_bioset(wpc->iomap.bdev, BIO_MAX_VECS,
1718			       REQ_OP_WRITE | wbc_to_write_flags(wbc),
1719			       GFP_NOFS, &iomap_ioend_bioset);
1720	bio->bi_iter.bi_sector = iomap_sector(&wpc->iomap, pos);
1721	bio->bi_end_io = iomap_writepage_end_bio;
1722	wbc_init_bio(wbc, bio);
1723	bio->bi_write_hint = inode->i_write_hint;
1724
1725	ioend = iomap_ioend_from_bio(bio);
1726	INIT_LIST_HEAD(&ioend->io_list);
1727	ioend->io_type = wpc->iomap.type;
1728	ioend->io_flags = wpc->iomap.flags;
1729	if (pos > wpc->iomap.offset)
1730		wpc->iomap.flags &= ~IOMAP_F_BOUNDARY;
1731	ioend->io_inode = inode;
1732	ioend->io_size = 0;
1733	ioend->io_offset = pos;
1734	ioend->io_sector = bio->bi_iter.bi_sector;
1735
1736	wpc->nr_folios = 0;
1737	return ioend;
1738}
1739
1740static bool iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t pos)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1741{
1742	if (wpc->iomap.offset == pos && (wpc->iomap.flags & IOMAP_F_BOUNDARY))
1743		return false;
1744	if ((wpc->iomap.flags & IOMAP_F_SHARED) !=
1745	    (wpc->ioend->io_flags & IOMAP_F_SHARED))
1746		return false;
1747	if (wpc->iomap.type != wpc->ioend->io_type)
1748		return false;
1749	if (pos != wpc->ioend->io_offset + wpc->ioend->io_size)
1750		return false;
1751	if (iomap_sector(&wpc->iomap, pos) !=
1752	    bio_end_sector(&wpc->ioend->io_bio))
1753		return false;
1754	/*
1755	 * Limit ioend bio chain lengths to minimise IO completion latency. This
1756	 * also prevents long tight loops ending page writeback on all the
1757	 * folios in the ioend.
1758	 */
1759	if (wpc->nr_folios >= IOEND_BATCH_SIZE)
1760		return false;
1761	return true;
1762}
1763
1764/*
1765 * Test to see if we have an existing ioend structure that we could append to
1766 * first; otherwise finish off the current ioend and start another.
1767 *
1768 * If a new ioend is created and cached, the old ioend is submitted to the block
1769 * layer instantly.  Batching optimisations are provided by higher level block
1770 * plugging.
1771 *
1772 * At the end of a writeback pass, there will be a cached ioend remaining on the
1773 * writepage context that the caller will need to submit.
1774 */
1775static int iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
1776		struct writeback_control *wbc, struct folio *folio,
1777		struct inode *inode, loff_t pos, loff_t end_pos,
1778		unsigned len)
1779{
1780	struct iomap_folio_state *ifs = folio->private;
 
1781	size_t poff = offset_in_folio(folio, pos);
1782	int error;
1783
1784	if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, pos)) {
1785new_ioend:
1786		error = iomap_submit_ioend(wpc, 0);
1787		if (error)
1788			return error;
1789		wpc->ioend = iomap_alloc_ioend(wpc, wbc, inode, pos);
1790	}
1791
1792	if (!bio_add_folio(&wpc->ioend->io_bio, folio, len, poff))
1793		goto new_ioend;
1794
1795	if (ifs)
1796		atomic_add(len, &ifs->write_bytes_pending);
1797
1798	/*
1799	 * Clamp io_offset and io_size to the incore EOF so that ondisk
1800	 * file size updates in the ioend completion are byte-accurate.
1801	 * This avoids recovering files with zeroed tail regions when
1802	 * writeback races with appending writes:
1803	 *
1804	 *    Thread 1:                  Thread 2:
1805	 *    ------------               -----------
1806	 *    write [A, A+B]
1807	 *    update inode size to A+B
1808	 *    submit I/O [A, A+BS]
1809	 *                               write [A+B, A+B+C]
1810	 *                               update inode size to A+B+C
1811	 *    <I/O completes, updates disk size to min(A+B+C, A+BS)>
1812	 *    <power failure>
1813	 *
1814	 *  After reboot:
1815	 *    1) with A+B+C < A+BS, the file has zero padding in range
1816	 *       [A+B, A+B+C]
1817	 *
1818	 *    |<     Block Size (BS)   >|
1819	 *    |DDDDDDDDDDDD0000000000000|
1820	 *    ^           ^        ^
1821	 *    A          A+B     A+B+C
1822	 *                       (EOF)
1823	 *
1824	 *    2) with A+B+C > A+BS, the file has zero padding in range
1825	 *       [A+B, A+BS]
1826	 *
1827	 *    |<     Block Size (BS)   >|<     Block Size (BS)    >|
1828	 *    |DDDDDDDDDDDD0000000000000|00000000000000000000000000|
1829	 *    ^           ^             ^           ^
1830	 *    A          A+B           A+BS       A+B+C
1831	 *                             (EOF)
1832	 *
1833	 *    D = Valid Data
1834	 *    0 = Zero Padding
1835	 *
1836	 * Note that this defeats the ability to chain the ioends of
1837	 * appending writes.
1838	 */
1839	wpc->ioend->io_size += len;
1840	if (wpc->ioend->io_offset + wpc->ioend->io_size > end_pos)
1841		wpc->ioend->io_size = end_pos - wpc->ioend->io_offset;
1842
1843	wbc_account_cgroup_owner(wbc, folio, len);
1844	return 0;
1845}
1846
1847static int iomap_writepage_map_blocks(struct iomap_writepage_ctx *wpc,
1848		struct writeback_control *wbc, struct folio *folio,
1849		struct inode *inode, u64 pos, u64 end_pos,
1850		unsigned dirty_len, unsigned *count)
1851{
1852	int error;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1853
1854	do {
1855		unsigned map_len;
 
 
 
 
 
 
 
 
1856
1857		error = wpc->ops->map_blocks(wpc, inode, pos, dirty_len);
1858		if (error)
1859			break;
1860		trace_iomap_writepage_map(inode, pos, dirty_len, &wpc->iomap);
 
 
 
 
 
 
 
 
 
 
1861
1862		map_len = min_t(u64, dirty_len,
1863			wpc->iomap.offset + wpc->iomap.length - pos);
1864		WARN_ON_ONCE(!folio->private && map_len < dirty_len);
1865
1866		switch (wpc->iomap.type) {
1867		case IOMAP_INLINE:
1868			WARN_ON_ONCE(1);
1869			error = -EIO;
1870			break;
1871		case IOMAP_HOLE:
1872			break;
1873		default:
1874			error = iomap_add_to_ioend(wpc, wbc, folio, inode, pos,
1875					end_pos, map_len);
1876			if (!error)
1877				(*count)++;
1878			break;
1879		}
1880		dirty_len -= map_len;
1881		pos += map_len;
1882	} while (dirty_len && !error);
1883
1884	/*
1885	 * We cannot cancel the ioend directly here on error.  We may have
1886	 * already set other pages under writeback and hence we have to run I/O
1887	 * completion to mark the error state of the pages under writeback
1888	 * appropriately.
1889	 *
1890	 * Just let the file system know what portion of the folio failed to
1891	 * map.
1892	 */
1893	if (error && wpc->ops->discard_folio)
1894		wpc->ops->discard_folio(folio, pos);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1895	return error;
1896}
1897
1898/*
1899 * Check interaction of the folio with the file end.
1900 *
1901 * If the folio is entirely beyond i_size, return false.  If it straddles
1902 * i_size, adjust end_pos and zero all data beyond i_size.
 
1903 */
1904static bool iomap_writepage_handle_eof(struct folio *folio, struct inode *inode,
1905		u64 *end_pos)
1906{
1907	u64 isize = i_size_read(inode);
 
 
 
 
 
1908
1909	if (*end_pos > isize) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1910		size_t poff = offset_in_folio(folio, isize);
1911		pgoff_t end_index = isize >> PAGE_SHIFT;
1912
1913		/*
1914		 * If the folio is entirely ouside of i_size, skip it.
1915		 *
1916		 * This can happen due to a truncate operation that is in
1917		 * progress and in that case truncate will finish it off once
1918		 * we've dropped the folio lock.
1919		 *
1920		 * Note that the pgoff_t used for end_index is an unsigned long.
1921		 * If the given offset is greater than 16TB on a 32-bit system,
1922		 * then if we checked if the folio is fully outside i_size with
1923		 * "if (folio->index >= end_index + 1)", "end_index + 1" would
1924		 * overflow and evaluate to 0.  Hence this folio would be
1925		 * redirtied and written out repeatedly, which would result in
1926		 * an infinite loop; the user program performing this operation
1927		 * would hang.  Instead, we can detect this situation by
1928		 * checking if the folio is totally beyond i_size or if its
1929		 * offset is just equal to the EOF.
1930		 */
1931		if (folio->index > end_index ||
1932		    (folio->index == end_index && poff == 0))
1933			return false;
1934
1935		/*
1936		 * The folio straddles i_size.
1937		 *
1938		 * It must be zeroed out on each and every writepage invocation
1939		 * because it may be mmapped:
1940		 *
1941		 *    A file is mapped in multiples of the page size.  For a
1942		 *    file that is not a multiple of the page size, the
1943		 *    remaining memory is zeroed when mapped, and writes to that
1944		 *    region are not written out to the file.
1945		 *
1946		 * Also adjust the end_pos to the end of file and skip writeback
1947		 * for all blocks entirely beyond i_size.
1948		 */
1949		folio_zero_segment(folio, poff, folio_size(folio));
1950		*end_pos = isize;
1951	}
1952
1953	return true;
1954}
1955
1956static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
1957		struct writeback_control *wbc, struct folio *folio)
1958{
1959	struct iomap_folio_state *ifs = folio->private;
1960	struct inode *inode = folio->mapping->host;
1961	u64 pos = folio_pos(folio);
1962	u64 end_pos = pos + folio_size(folio);
1963	u64 end_aligned = 0;
1964	unsigned count = 0;
1965	int error = 0;
1966	u32 rlen;
1967
1968	WARN_ON_ONCE(!folio_test_locked(folio));
1969	WARN_ON_ONCE(folio_test_dirty(folio));
1970	WARN_ON_ONCE(folio_test_writeback(folio));
1971
1972	trace_iomap_writepage(inode, pos, folio_size(folio));
1973
1974	if (!iomap_writepage_handle_eof(folio, inode, &end_pos)) {
1975		folio_unlock(folio);
1976		return 0;
1977	}
1978	WARN_ON_ONCE(end_pos <= pos);
1979
1980	if (i_blocks_per_folio(inode, folio) > 1) {
1981		if (!ifs) {
1982			ifs = ifs_alloc(inode, folio, 0);
1983			iomap_set_range_dirty(folio, 0, end_pos - pos);
1984		}
1985
1986		/*
1987		 * Keep the I/O completion handler from clearing the writeback
1988		 * bit until we have submitted all blocks by adding a bias to
1989		 * ifs->write_bytes_pending, which is dropped after submitting
1990		 * all blocks.
1991		 */
1992		WARN_ON_ONCE(atomic_read(&ifs->write_bytes_pending) != 0);
1993		atomic_inc(&ifs->write_bytes_pending);
1994	}
1995
1996	/*
1997	 * Set the writeback bit ASAP, as the I/O completion for the single
1998	 * block per folio case happen hit as soon as we're submitting the bio.
1999	 */
2000	folio_start_writeback(folio);
2001
2002	/*
2003	 * Walk through the folio to find dirty areas to write back.
2004	 */
2005	end_aligned = round_up(end_pos, i_blocksize(inode));
2006	while ((rlen = iomap_find_dirty_range(folio, &pos, end_aligned))) {
2007		error = iomap_writepage_map_blocks(wpc, wbc, folio, inode,
2008				pos, end_pos, rlen, &count);
2009		if (error)
2010			break;
2011		pos += rlen;
2012	}
2013
2014	if (count)
2015		wpc->nr_folios++;
2016
2017	/*
2018	 * We can have dirty bits set past end of file in page_mkwrite path
2019	 * while mapping the last partial folio. Hence it's better to clear
2020	 * all the dirty bits in the folio here.
2021	 */
2022	iomap_clear_range_dirty(folio, 0, folio_size(folio));
2023
2024	/*
2025	 * Usually the writeback bit is cleared by the I/O completion handler.
2026	 * But we may end up either not actually writing any blocks, or (when
2027	 * there are multiple blocks in a folio) all I/O might have finished
2028	 * already at this point.  In that case we need to clear the writeback
2029	 * bit ourselves right after unlocking the page.
2030	 */
2031	folio_unlock(folio);
2032	if (ifs) {
2033		if (atomic_dec_and_test(&ifs->write_bytes_pending))
2034			folio_end_writeback(folio);
2035	} else {
2036		if (!count)
2037			folio_end_writeback(folio);
2038	}
2039	mapping_set_error(inode->i_mapping, error);
2040	return error;
2041}
2042
2043int
2044iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
2045		struct iomap_writepage_ctx *wpc,
2046		const struct iomap_writeback_ops *ops)
2047{
2048	struct folio *folio = NULL;
2049	int error;
2050
2051	/*
2052	 * Writeback from reclaim context should never happen except in the case
2053	 * of a VM regression so warn about it and refuse to write the data.
2054	 */
2055	if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC | PF_KSWAPD)) ==
2056			PF_MEMALLOC))
2057		return -EIO;
2058
2059	wpc->ops = ops;
2060	while ((folio = writeback_iter(mapping, wbc, folio, &error)))
2061		error = iomap_writepage_map(wpc, wbc, folio);
2062	return iomap_submit_ioend(wpc, error);
 
2063}
2064EXPORT_SYMBOL_GPL(iomap_writepages);
2065
2066static int __init iomap_buffered_init(void)
2067{
2068	return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
2069			   offsetof(struct iomap_ioend, io_bio),
2070			   BIOSET_NEED_BVECS);
2071}
2072fs_initcall(iomap_buffered_init);