fs/iomap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2010 Red Hat, Inc.
   4  * Copyright (c) 2016-2018 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/uaccess.h>
  11 #include <linux/gfp.h>
  12 #include <linux/migrate.h>
  13 #include <linux/mm.h>
  14 #include <linux/mm_inline.h>
  15 #include <linux/swap.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/pagevec.h>
  18 #include <linux/file.h>
  19 #include <linux/uio.h>
  20 #include <linux/backing-dev.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/task_io_accounting_ops.h>
  23 #include <linux/dax.h>
  24 #include <linux/sched/signal.h>
  25
  26 #include "internal.h"
  27
  28 /*
  29  * Execute a iomap write on a segment of the mapping that spans a
  30  * contiguous range of pages that have identical block mapping state.
  31  *
  32  * This avoids the need to map pages individually, do individual allocations
  33  * for each page and most importantly avoid the need for filesystem specific
  34  * locking per page. Instead, all the operations are amortised over the entire
  35  * range of pages. It is assumed that the filesystems will lock whatever
  36  * resources they require in the iomap_begin call, and release them in the
  37  * iomap_end call.
  38  */
  39 loff_t
  40 iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
  41                 const struct iomap_ops *ops, void *data, iomap_actor_t actor)
  42 {
  43         struct iomap iomap = { 0 };
  44         loff_t written = 0, ret;
  45
  46         /*
  47          * Need to map a range from start position for length bytes. This can
  48          * span multiple pages - it is only guaranteed to return a range of a
  49          * single type of pages (e.g. all into a hole, all mapped or all
  50          * unwritten). Failure at this point has nothing to undo.
  51          *
  52          * If allocation is required for this range, reserve the space now so
  53          * that the allocation is guaranteed to succeed later on. Once we copy
  54          * the data into the page cache pages, then we cannot fail otherwise we
  55          * expose transient stale data. If the reserve fails, we can safely
  56          * back out at this point as there is nothing to undo.
  57          */
  58         ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
  59         if (ret)
  60                 return ret;
  61         if (WARN_ON(iomap.offset > pos))
  62                 return -EIO;
  63         if (WARN_ON(iomap.length == 0))
  64                 return -EIO;
  65
  66         /*
  67          * Cut down the length to the one actually provided by the filesystem,
  68          * as it might not be able to give us the whole size that we requested.
  69          */
  70         if (iomap.offset + iomap.length < pos + length)
  71                 length = iomap.offset + iomap.length - pos;
  72
  73         /*
  74          * Now that we have guaranteed that the space allocation will succeed.
  75          * we can do the copy-in page by page without having to worry about
  76          * failures exposing transient data.
  77          */
  78         written = actor(inode, pos, length, data, &iomap);
  79
  80         /*
  81          * Now the data has been copied, commit the range we've copied.  This
  82          * should not fail unless the filesystem has had a fatal error.
  83          */
  84         if (ops->iomap_end) {
  85                 ret = ops->iomap_end(inode, pos, length,
  86                                      written > 0 ? written : 0,
  87                                      flags, &iomap);
  88         }
  89
  90         return written ? written : ret;
  91 }
  92
  93 static sector_t
  94 iomap_sector(struct iomap *iomap, loff_t pos)
  95 {
  96         return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
  97 }
  98
  99 static struct iomap_page *
 100 iomap_page_create(struct inode *inode, struct page *page)
 101 {
 102         struct iomap_page *iop = to_iomap_page(page);
 103
 104         if (iop || i_blocksize(inode) == PAGE_SIZE)
 105                 return iop;
 106
 107         iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
 108         atomic_set(&iop->read_count, 0);
 109         atomic_set(&iop->write_count, 0);
 110         bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
 111
 112         /*
 113          * migrate_page_move_mapping() assumes that pages with private data have
 114          * their count elevated by 1.
 115          */
 116         get_page(page);
 117         set_page_private(page, (unsigned long)iop);
 118         SetPagePrivate(page);
 119         return iop;
 120 }
 121
 122 static void
 123 iomap_page_release(struct page *page)
 124 {
 125         struct iomap_page *iop = to_iomap_page(page);
 126
 127         if (!iop)
 128                 return;
 129         WARN_ON_ONCE(atomic_read(&iop->read_count));
 130         WARN_ON_ONCE(atomic_read(&iop->write_count));
 131         ClearPagePrivate(page);
 132         set_page_private(page, 0);
 133         put_page(page);
 134         kfree(iop);
 135 }
 136
 137 /*
 138  * Calculate the range inside the page that we actually need to read.
 139  */
 140 static void
 141 iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
 142                 loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
 143 {
 144         loff_t orig_pos = *pos;
 145         loff_t isize = i_size_read(inode);
 146         unsigned block_bits = inode->i_blkbits;
 147         unsigned block_size = (1 << block_bits);
 148         unsigned poff = offset_in_page(*pos);
 149         unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
 150         unsigned first = poff >> block_bits;
 151         unsigned last = (poff + plen - 1) >> block_bits;
 152
 153         /*
 154          * If the block size is smaller than the page size we need to check the
 155          * per-block uptodate status and adjust the offset and length if needed
 156          * to avoid reading in already uptodate ranges.
 157          */
 158         if (iop) {
 159                 unsigned int i;
 160
 161                 /* move forward for each leading block marked uptodate */
 162                 for (i = first; i <= last; i++) {
 163                         if (!test_bit(i, iop->uptodate))
 164                                 break;
 165                         *pos += block_size;
 166                         poff += block_size;
 167                         plen -= block_size;
 168                         first++;
 169                 }
 170
 171                 /* truncate len if we find any trailing uptodate block(s) */
 172                 for ( ; i <= last; i++) {
 173                         if (test_bit(i, iop->uptodate)) {
 174                                 plen -= (last - i + 1) * block_size;
 175                                 last = i - 1;
 176                                 break;
 177                         }
 178                 }
 179         }
 180
 181         /*
 182          * If the extent spans the block that contains the i_size we need to
 183          * handle both halves separately so that we properly zero data in the
 184          * page cache for blocks that are entirely outside of i_size.
 185          */
 186         if (orig_pos <= isize && orig_pos + length > isize) {
 187                 unsigned end = offset_in_page(isize - 1) >> block_bits;
 188
 189                 if (first <= end && last > end)
 190                         plen -= (last - end) * block_size;
 191         }
 192
 193         *offp = poff;
 194         *lenp = plen;
 195 }
 196
 197 static void
 198 iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
 199 {
 200         struct iomap_page *iop = to_iomap_page(page);
 201         struct inode *inode = page->mapping->host;
 202         unsigned first = off >> inode->i_blkbits;
 203         unsigned last = (off + len - 1) >> inode->i_blkbits;
 204         unsigned int i;
 205         bool uptodate = true;
 206
 207         if (iop) {
 208                 for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
 209                         if (i >= first && i <= last)
 210                                 set_bit(i, iop->uptodate);
 211                         else if (!test_bit(i, iop->uptodate))
 212                                 uptodate = false;
 213                 }
 214         }
 215
 216         if (uptodate && !PageError(page))
 217                 SetPageUptodate(page);
 218 }
 219
 220 static void
 221 iomap_read_finish(struct iomap_page *iop, struct page *page)
 222 {
 223         if (!iop || atomic_dec_and_test(&iop->read_count))
 224                 unlock_page(page);
 225 }
 226
 227 static void
 228 iomap_read_page_end_io(struct bio_vec *bvec, int error)
 229 {
 230         struct page *page = bvec->bv_page;
 231         struct iomap_page *iop = to_iomap_page(page);
 232
 233         if (unlikely(error)) {
 234                 ClearPageUptodate(page);
 235                 SetPageError(page);
 236         } else {
 237                 iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);
 238         }
 239
 240         iomap_read_finish(iop, page);
 241 }
 242
 243 static void
 244 iomap_read_end_io(struct bio *bio)
 245 {
 246         int error = blk_status_to_errno(bio->bi_status);
 247         struct bio_vec *bvec;
 248         struct bvec_iter_all iter_all;
 249
 250         bio_for_each_segment_all(bvec, bio, iter_all)
 251                 iomap_read_page_end_io(bvec, error);
 252         bio_put(bio);
 253 }
 254
 255 struct iomap_readpage_ctx {
 256         struct page             *cur_page;
 257         bool                    cur_page_in_bio;
 258         bool                    is_readahead;
 259         struct bio              *bio;
 260         struct list_head        *pages;
 261 };
 262
 263 static void
 264 iomap_read_inline_data(struct inode *inode, struct page *page,
 265                 struct iomap *iomap)
 266 {
 267         size_t size = i_size_read(inode);
 268         void *addr;
 269
 270         if (PageUptodate(page))
 271                 return;
 272
 273         BUG_ON(page->index);
 274         BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
 275
 276         addr = kmap_atomic(page);
 277         memcpy(addr, iomap->inline_data, size);
 278         memset(addr + size, 0, PAGE_SIZE - size);
 279         kunmap_atomic(addr);
 280         SetPageUptodate(page);
 281 }
 282
 283 static loff_t
 284 iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 285                 struct iomap *iomap)
 286 {
 287         struct iomap_readpage_ctx *ctx = data;
 288         struct page *page = ctx->cur_page;
 289         struct iomap_page *iop = iomap_page_create(inode, page);
 290         bool is_contig = false;
 291         loff_t orig_pos = pos;
 292         unsigned poff, plen;
 293         sector_t sector;
 294
 295         if (iomap->type == IOMAP_INLINE) {
 296                 WARN_ON_ONCE(pos);
 297                 iomap_read_inline_data(inode, page, iomap);
 298                 return PAGE_SIZE;
 299         }
 300
 301         /* zero post-eof blocks as the page may be mapped */
 302         iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
 303         if (plen == 0)
 304                 goto done;
 305
 306         if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) {
 307                 zero_user(page, poff, plen);
 308                 iomap_set_range_uptodate(page, poff, plen);
 309                 goto done;
 310         }
 311
 312         ctx->cur_page_in_bio = true;
 313
 314         /*
 315          * Try to merge into a previous segment if we can.
 316          */
 317         sector = iomap_sector(iomap, pos);
 318         if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
 319                 if (__bio_try_merge_page(ctx->bio, page, plen, poff, true))
 320                         goto done;
 321                 is_contig = true;
 322         }
 323
 324         /*
 325          * If we start a new segment we need to increase the read count, and we
 326          * need to do so before submitting any previous full bio to make sure
 327          * that we don't prematurely unlock the page.
 328          */
 329         if (iop)
 330                 atomic_inc(&iop->read_count);
 331
 332         if (!ctx->bio || !is_contig || bio_full(ctx->bio)) {
 333                 gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
 334                 int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
 335
 336                 if (ctx->bio)
 337                         submit_bio(ctx->bio);
 338
 339                 if (ctx->is_readahead) /* same as readahead_gfp_mask */
 340                         gfp |= __GFP_NORETRY | __GFP_NOWARN;
 341                 ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
 342                 ctx->bio->bi_opf = REQ_OP_READ;
 343                 if (ctx->is_readahead)
 344                         ctx->bio->bi_opf |= REQ_RAHEAD;
 345                 ctx->bio->bi_iter.bi_sector = sector;
 346                 bio_set_dev(ctx->bio, iomap->bdev);
 347                 ctx->bio->bi_end_io = iomap_read_end_io;
 348         }
 349
 350         bio_add_page(ctx->bio, page, plen, poff);
 351 done:
 352         /*
 353          * Move the caller beyond our range so that it keeps making progress.
 354          * For that we have to include any leading non-uptodate ranges, but
 355          * we can skip trailing ones as they will be handled in the next
 356          * iteration.
 357          */
 358         return pos - orig_pos + plen;
 359 }
 360
 361 int
 362 iomap_readpage(struct page *page, const struct iomap_ops *ops)
 363 {
 364         struct iomap_readpage_ctx ctx = { .cur_page = page };
 365         struct inode *inode = page->mapping->host;
 366         unsigned poff;
 367         loff_t ret;
 368
 369         for (poff = 0; poff < PAGE_SIZE; poff += ret) {
 370                 ret = iomap_apply(inode, page_offset(page) + poff,
 371                                 PAGE_SIZE - poff, 0, ops, &ctx,
 372                                 iomap_readpage_actor);
 373                 if (ret <= 0) {
 374                         WARN_ON_ONCE(ret == 0);
 375                         SetPageError(page);
 376                         break;
 377                 }
 378         }
 379
 380         if (ctx.bio) {
 381                 submit_bio(ctx.bio);
 382                 WARN_ON_ONCE(!ctx.cur_page_in_bio);
 383         } else {
 384                 WARN_ON_ONCE(ctx.cur_page_in_bio);
 385                 unlock_page(page);
 386         }
 387
 388         /*
 389          * Just like mpage_readpages and block_read_full_page we always
 390          * return 0 and just mark the page as PageError on errors.  This
 391          * should be cleaned up all through the stack eventually.
 392          */
 393         return 0;
 394 }
 395 EXPORT_SYMBOL_GPL(iomap_readpage);
 396
 397 static struct page *
 398 iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,
 399                 loff_t length, loff_t *done)
 400 {
 401         while (!list_empty(pages)) {
 402                 struct page *page = lru_to_page(pages);
 403
 404                 if (page_offset(page) >= (u64)pos + length)
 405                         break;
 406
 407                 list_del(&page->lru);
 408                 if (!add_to_page_cache_lru(page, inode->i_mapping, page->index,
 409                                 GFP_NOFS))
 410                         return page;
 411
 412                 /*
 413                  * If we already have a page in the page cache at index we are
 414                  * done.  Upper layers don't care if it is uptodate after the
 415                  * readpages call itself as every page gets checked again once
 416                  * actually needed.
 417                  */
 418                 *done += PAGE_SIZE;
 419                 put_page(page);
 420         }
 421
 422         return NULL;
 423 }
 424
 425 static loff_t
 426 iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
 427                 void *data, struct iomap *iomap)
 428 {
 429         struct iomap_readpage_ctx *ctx = data;
 430         loff_t done, ret;
 431
 432         for (done = 0; done < length; done += ret) {
 433                 if (ctx->cur_page && offset_in_page(pos + done) == 0) {
 434                         if (!ctx->cur_page_in_bio)
 435                                 unlock_page(ctx->cur_page);
 436                         put_page(ctx->cur_page);
 437                         ctx->cur_page = NULL;
 438                 }
 439                 if (!ctx->cur_page) {
 440                         ctx->cur_page = iomap_next_page(inode, ctx->pages,
 441                                         pos, length, &done);
 442                         if (!ctx->cur_page)
 443                                 break;
 444                         ctx->cur_page_in_bio = false;
 445                 }
 446                 ret = iomap_readpage_actor(inode, pos + done, length - done,
 447                                 ctx, iomap);
 448         }
 449
 450         return done;
 451 }
 452
 453 int
 454 iomap_readpages(struct address_space *mapping, struct list_head *pages,
 455                 unsigned nr_pages, const struct iomap_ops *ops)
 456 {
 457         struct iomap_readpage_ctx ctx = {
 458                 .pages          = pages,
 459                 .is_readahead   = true,
 460         };
 461         loff_t pos = page_offset(list_entry(pages->prev, struct page, lru));
 462         loff_t last = page_offset(list_entry(pages->next, struct page, lru));
 463         loff_t length = last - pos + PAGE_SIZE, ret = 0;
 464
 465         while (length > 0) {
 466                 ret = iomap_apply(mapping->host, pos, length, 0, ops,
 467                                 &ctx, iomap_readpages_actor);
 468                 if (ret <= 0) {
 469                         WARN_ON_ONCE(ret == 0);
 470                         goto done;
 471                 }
 472                 pos += ret;
 473                 length -= ret;
 474         }
 475         ret = 0;
 476 done:
 477         if (ctx.bio)
 478                 submit_bio(ctx.bio);
 479         if (ctx.cur_page) {
 480                 if (!ctx.cur_page_in_bio)
 481                         unlock_page(ctx.cur_page);
 482                 put_page(ctx.cur_page);
 483         }
 484
 485         /*
 486          * Check that we didn't lose a page due to the arcance calling
 487          * conventions..
 488          */
 489         WARN_ON_ONCE(!ret && !list_empty(ctx.pages));
 490         return ret;
 491 }
 492 EXPORT_SYMBOL_GPL(iomap_readpages);
 493
 494 /*
 495  * iomap_is_partially_uptodate checks whether blocks within a page are
 496  * uptodate or not.
 497  *
 498  * Returns true if all blocks which correspond to a file portion
 499  * we want to read within the page are uptodate.
 500  */
 501 int
 502 iomap_is_partially_uptodate(struct page *page, unsigned long from,
 503                 unsigned long count)
 504 {
 505         struct iomap_page *iop = to_iomap_page(page);
 506         struct inode *inode = page->mapping->host;
 507         unsigned len, first, last;
 508         unsigned i;
 509
 510         /* Limit range to one page */
 511         len = min_t(unsigned, PAGE_SIZE - from, count);
 512
 513         /* First and last blocks in range within page */
 514         first = from >> inode->i_blkbits;
 515         last = (from + len - 1) >> inode->i_blkbits;
 516
 517         if (iop) {
 518                 for (i = first; i <= last; i++)
 519                         if (!test_bit(i, iop->uptodate))
 520                                 return 0;
 521                 return 1;
 522         }
 523
 524         return 0;
 525 }
 526 EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
 527
 528 int
 529 iomap_releasepage(struct page *page, gfp_t gfp_mask)
 530 {
 531         /*
 532          * mm accommodates an old ext3 case where clean pages might not have had
 533          * the dirty bit cleared. Thus, it can send actual dirty pages to
 534          * ->releasepage() via shrink_active_list(), skip those here.
 535          */
 536         if (PageDirty(page) || PageWriteback(page))
 537                 return 0;
 538         iomap_page_release(page);
 539         return 1;
 540 }
 541 EXPORT_SYMBOL_GPL(iomap_releasepage);
 542
 543 void
 544 iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
 545 {
 546         /*
 547          * If we are invalidating the entire page, clear the dirty state from it
 548          * and release it to avoid unnecessary buildup of the LRU.
 549          */
 550         if (offset == 0 && len == PAGE_SIZE) {
 551                 WARN_ON_ONCE(PageWriteback(page));
 552                 cancel_dirty_page(page);
 553                 iomap_page_release(page);
 554         }
 555 }
 556 EXPORT_SYMBOL_GPL(iomap_invalidatepage);
 557
 558 #ifdef CONFIG_MIGRATION
 559 int
 560 iomap_migrate_page(struct address_space *mapping, struct page *newpage,
 561                 struct page *page, enum migrate_mode mode)
 562 {
 563         int ret;
 564
 565         ret = migrate_page_move_mapping(mapping, newpage, page, mode, 0);
 566         if (ret != MIGRATEPAGE_SUCCESS)
 567                 return ret;
 568
 569         if (page_has_private(page)) {
 570                 ClearPagePrivate(page);
 571                 get_page(newpage);
 572                 set_page_private(newpage, page_private(page));
 573                 set_page_private(page, 0);
 574                 put_page(page);
 575                 SetPagePrivate(newpage);
 576         }
 577
 578         if (mode != MIGRATE_SYNC_NO_COPY)
 579                 migrate_page_copy(newpage, page);
 580         else
 581                 migrate_page_states(newpage, page);
 582         return MIGRATEPAGE_SUCCESS;
 583 }
 584 EXPORT_SYMBOL_GPL(iomap_migrate_page);
 585 #endif /* CONFIG_MIGRATION */
 586
 587 static void
 588 iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
 589 {
 590         loff_t i_size = i_size_read(inode);
 591
 592         /*
 593          * Only truncate newly allocated pages beyoned EOF, even if the
 594          * write started inside the existing inode size.
 595          */
 596         if (pos + len > i_size)
 597                 truncate_pagecache_range(inode, max(pos, i_size), pos + len);
 598 }
 599
 600 static int
 601 iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page,
 602                 unsigned poff, unsigned plen, unsigned from, unsigned to,
 603                 struct iomap *iomap)
 604 {
 605         struct bio_vec bvec;
 606         struct bio bio;
 607
 608         if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) {
 609                 zero_user_segments(page, poff, from, to, poff + plen);
 610                 iomap_set_range_uptodate(page, poff, plen);
 611                 return 0;
 612         }
 613
 614         bio_init(&bio, &bvec, 1);
 615         bio.bi_opf = REQ_OP_READ;
 616         bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
 617         bio_set_dev(&bio, iomap->bdev);
 618         __bio_add_page(&bio, page, plen, poff);
 619         return submit_bio_wait(&bio);
 620 }
 621
 622 static int
 623 __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
 624                 struct page *page, struct iomap *iomap)
 625 {
 626         struct iomap_page *iop = iomap_page_create(inode, page);
 627         loff_t block_size = i_blocksize(inode);
 628         loff_t block_start = pos & ~(block_size - 1);
 629         loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
 630         unsigned from = offset_in_page(pos), to = from + len, poff, plen;
 631         int status = 0;
 632
 633         if (PageUptodate(page))
 634                 return 0;
 635
 636         do {
 637                 iomap_adjust_read_range(inode, iop, &block_start,
 638                                 block_end - block_start, &poff, &plen);
 639                 if (plen == 0)
 640                         break;
 641
 642                 if ((from > poff && from < poff + plen) ||
 643                     (to > poff && to < poff + plen)) {
 644                         status = iomap_read_page_sync(inode, block_start, page,
 645                                         poff, plen, from, to, iomap);
 646                         if (status)
 647                                 break;
 648                 }
 649
 650         } while ((block_start += plen) < block_end);
 651
 652         return status;
 653 }
 654
 655 static int
 656 iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
 657                 struct page **pagep, struct iomap *iomap)
 658 {
 659         const struct iomap_page_ops *page_ops = iomap->page_ops;
 660         pgoff_t index = pos >> PAGE_SHIFT;
 661         struct page *page;
 662         int status = 0;
 663
 664         BUG_ON(pos + len > iomap->offset + iomap->length);
 665
 666         if (fatal_signal_pending(current))
 667                 return -EINTR;
 668
 669         if (page_ops && page_ops->page_prepare) {
 670                 status = page_ops->page_prepare(inode, pos, len, iomap);
 671                 if (status)
 672                         return status;
 673         }
 674
 675         page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
 676         if (!page) {
 677                 status = -ENOMEM;
 678                 goto out_no_page;
 679         }
 680
 681         if (iomap->type == IOMAP_INLINE)
 682                 iomap_read_inline_data(inode, page, iomap);
 683         else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
 684                 status = __block_write_begin_int(page, pos, len, NULL, iomap);
 685         else
 686                 status = __iomap_write_begin(inode, pos, len, page, iomap);
 687
 688         if (unlikely(status))
 689                 goto out_unlock;
 690
 691         *pagep = page;
 692         return 0;
 693
 694 out_unlock:
 695         unlock_page(page);
 696         put_page(page);
 697         iomap_write_failed(inode, pos, len);
 698
 699 out_no_page:
 700         if (page_ops && page_ops->page_done)
 701                 page_ops->page_done(inode, pos, 0, NULL, iomap);
 702         return status;
 703 }
 704
 705 int
 706 iomap_set_page_dirty(struct page *page)
 707 {
 708         struct address_space *mapping = page_mapping(page);
 709         int newly_dirty;
 710
 711         if (unlikely(!mapping))
 712                 return !TestSetPageDirty(page);
 713
 714         /*
 715          * Lock out page->mem_cgroup migration to keep PageDirty
 716          * synchronized with per-memcg dirty page counters.
 717          */
 718         lock_page_memcg(page);
 719         newly_dirty = !TestSetPageDirty(page);
 720         if (newly_dirty)
 721                 __set_page_dirty(page, mapping, 0);
 722         unlock_page_memcg(page);
 723
 724         if (newly_dirty)
 725                 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 726         return newly_dirty;
 727 }
 728 EXPORT_SYMBOL_GPL(iomap_set_page_dirty);
 729
 730 static int
 731 __iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
 732                 unsigned copied, struct page *page, struct iomap *iomap)
 733 {
 734         flush_dcache_page(page);
 735
 736         /*
 737          * The blocks that were entirely written will now be uptodate, so we
 738          * don't have to worry about a readpage reading them and overwriting a
 739          * partial write.  However if we have encountered a short write and only
 740          * partially written into a block, it will not be marked uptodate, so a
 741          * readpage might come in and destroy our partial write.
 742          *
 743          * Do the simplest thing, and just treat any short write to a non
 744          * uptodate page as a zero-length write, and force the caller to redo
 745          * the whole thing.
 746          */
 747         if (unlikely(copied < len && !PageUptodate(page)))
 748                 return 0;
 749         iomap_set_range_uptodate(page, offset_in_page(pos), len);
 750         iomap_set_page_dirty(page);
 751         return copied;
 752 }
 753
 754 static int
 755 iomap_write_end_inline(struct inode *inode, struct page *page,
 756                 struct iomap *iomap, loff_t pos, unsigned copied)
 757 {
 758         void *addr;
 759
 760         WARN_ON_ONCE(!PageUptodate(page));
 761         BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
 762
 763         addr = kmap_atomic(page);
 764         memcpy(iomap->inline_data + pos, addr + pos, copied);
 765         kunmap_atomic(addr);
 766
 767         mark_inode_dirty(inode);
 768         return copied;
 769 }
 770
 771 static int
 772 iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
 773                 unsigned copied, struct page *page, struct iomap *iomap)
 774 {
 775         const struct iomap_page_ops *page_ops = iomap->page_ops;
 776         int ret;
 777
 778         if (iomap->type == IOMAP_INLINE) {
 779                 ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
 780         } else if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
 781                 ret = block_write_end(NULL, inode->i_mapping, pos, len, copied,
 782                                 page, NULL);
 783         } else {
 784                 ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
 785         }
 786
 787         __generic_write_end(inode, pos, ret, page);
 788         if (page_ops && page_ops->page_done)
 789                 page_ops->page_done(inode, pos, copied, page, iomap);
 790         put_page(page);
 791
 792         if (ret < len)
 793                 iomap_write_failed(inode, pos, len);
 794         return ret;
 795 }
 796
 797 static loff_t
 798 iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 799                 struct iomap *iomap)
 800 {
 801         struct iov_iter *i = data;
 802         long status = 0;
 803         ssize_t written = 0;
 804         unsigned int flags = AOP_FLAG_NOFS;
 805
 806         do {
 807                 struct page *page;
 808                 unsigned long offset;   /* Offset into pagecache page */
 809                 unsigned long bytes;    /* Bytes to write to page */
 810                 size_t copied;          /* Bytes copied from user */
 811
 812                 offset = offset_in_page(pos);
 813                 bytes = min_t(unsigned long, PAGE_SIZE - offset,
 814                                                 iov_iter_count(i));
 815 again:
 816                 if (bytes > length)
 817                         bytes = length;
 818
 819                 /*
 820                  * Bring in the user page that we will copy from _first_.
 821                  * Otherwise there's a nasty deadlock on copying from the
 822                  * same page as we're writing to, without it being marked
 823                  * up-to-date.
 824                  *
 825                  * Not only is this an optimisation, but it is also required
 826                  * to check that the address is actually valid, when atomic
 827                  * usercopies are used, below.
 828                  */
 829                 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
 830                         status = -EFAULT;
 831                         break;
 832                 }
 833
 834                 status = iomap_write_begin(inode, pos, bytes, flags, &page,
 835                                 iomap);
 836                 if (unlikely(status))
 837                         break;
 838
 839                 if (mapping_writably_mapped(inode->i_mapping))
 840                         flush_dcache_page(page);
 841
 842                 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
 843
 844                 flush_dcache_page(page);
 845
 846                 status = iomap_write_end(inode, pos, bytes, copied, page,
 847                                 iomap);
 848                 if (unlikely(status < 0))
 849                         break;
 850                 copied = status;
 851
 852                 cond_resched();
 853
 854                 iov_iter_advance(i, copied);
 855                 if (unlikely(copied == 0)) {
 856                         /*
 857                          * If we were unable to copy any data at all, we must
 858                          * fall back to a single segment length write.
 859                          *
 860                          * If we didn't fallback here, we could livelock
 861                          * because not all segments in the iov can be copied at
 862                          * once without a pagefault.
 863                          */
 864                         bytes = min_t(unsigned long, PAGE_SIZE - offset,
 865                                                 iov_iter_single_seg_count(i));
 866                         goto again;
 867                 }
 868                 pos += copied;
 869                 written += copied;
 870                 length -= copied;
 871
 872                 balance_dirty_pages_ratelimited(inode->i_mapping);
 873         } while (iov_iter_count(i) && length);
 874
 875         return written ? written : status;
 876 }
 877
 878 ssize_t
 879 iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
 880                 const struct iomap_ops *ops)
 881 {
 882         struct inode *inode = iocb->ki_filp->f_mapping->host;
 883         loff_t pos = iocb->ki_pos, ret = 0, written = 0;
 884
 885         while (iov_iter_count(iter)) {
 886                 ret = iomap_apply(inode, pos, iov_iter_count(iter),
 887                                 IOMAP_WRITE, ops, iter, iomap_write_actor);
 888                 if (ret <= 0)
 889                         break;
 890                 pos += ret;
 891                 written += ret;
 892         }
 893
 894         return written ? written : ret;
 895 }
 896 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
 897
 898 static struct page *
 899 __iomap_read_page(struct inode *inode, loff_t offset)
 900 {
 901         struct address_space *mapping = inode->i_mapping;
 902         struct page *page;
 903
 904         page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
 905         if (IS_ERR(page))
 906                 return page;
 907         if (!PageUptodate(page)) {
 908                 put_page(page);
 909                 return ERR_PTR(-EIO);
 910         }
 911         return page;
 912 }
 913
 914 static loff_t
 915 iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 916                 struct iomap *iomap)
 917 {
 918         long status = 0;
 919         ssize_t written = 0;
 920
 921         do {
 922                 struct page *page, *rpage;
 923                 unsigned long offset;   /* Offset into pagecache page */
 924                 unsigned long bytes;    /* Bytes to write to page */
 925
 926                 offset = offset_in_page(pos);
 927                 bytes = min_t(loff_t, PAGE_SIZE - offset, length);
 928
 929                 rpage = __iomap_read_page(inode, pos);
 930                 if (IS_ERR(rpage))
 931                         return PTR_ERR(rpage);
 932
 933                 status = iomap_write_begin(inode, pos, bytes,
 934                                            AOP_FLAG_NOFS, &page, iomap);
 935                 put_page(rpage);
 936                 if (unlikely(status))
 937                         return status;
 938
 939                 WARN_ON_ONCE(!PageUptodate(page));
 940
 941                 status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
 942                 if (unlikely(status <= 0)) {
 943                         if (WARN_ON_ONCE(status == 0))
 944                                 return -EIO;
 945                         return status;
 946                 }
 947
 948                 cond_resched();
 949
 950                 pos += status;
 951                 written += status;
 952                 length -= status;
 953
 954                 balance_dirty_pages_ratelimited(inode->i_mapping);
 955         } while (length);
 956
 957         return written;
 958 }
 959
 960 int
 961 iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
 962                 const struct iomap_ops *ops)
 963 {
 964         loff_t ret;
 965
 966         while (len) {
 967                 ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
 968                                 iomap_dirty_actor);
 969                 if (ret <= 0)
 970                         return ret;
 971                 pos += ret;
 972                 len -= ret;
 973         }
 974
 975         return 0;
 976 }
 977 EXPORT_SYMBOL_GPL(iomap_file_dirty);
 978
 979 static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
 980                 unsigned bytes, struct iomap *iomap)
 981 {
 982         struct page *page;
 983         int status;
 984
 985         status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page,
 986                                    iomap);
 987         if (status)
 988                 return status;
 989
 990         zero_user(page, offset, bytes);
 991         mark_page_accessed(page);
 992
 993         return iomap_write_end(inode, pos, bytes, bytes, page, iomap);
 994 }
 995
 996 static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
 997                 struct iomap *iomap)
 998 {
 999         return __dax_zero_page_range(iomap->bdev, iomap->dax_dev,
1000                         iomap_sector(iomap, pos & PAGE_MASK), offset, bytes);
1001 }
1002
1003 static loff_t
1004 iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
1005                 void *data, struct iomap *iomap)
1006 {
1007         bool *did_zero = data;
1008         loff_t written = 0;
1009         int status;
1010
1011         /* already zeroed?  we're done. */
1012         if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
1013                 return count;
1014
1015         do {
1016                 unsigned offset, bytes;
1017
1018                 offset = offset_in_page(pos);
1019                 bytes = min_t(loff_t, PAGE_SIZE - offset, count);
1020
1021                 if (IS_DAX(inode))
1022                         status = iomap_dax_zero(pos, offset, bytes, iomap);
1023                 else
1024                         status = iomap_zero(inode, pos, offset, bytes, iomap);
1025                 if (status < 0)
1026                         return status;
1027
1028                 pos += bytes;
1029                 count -= bytes;
1030                 written += bytes;
1031                 if (did_zero)
1032                         *did_zero = true;
1033         } while (count > 0);
1034
1035         return written;
1036 }
1037
1038 int
1039 iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
1040                 const struct iomap_ops *ops)
1041 {
1042         loff_t ret;
1043
1044         while (len > 0) {
1045                 ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
1046                                 ops, did_zero, iomap_zero_range_actor);
1047                 if (ret <= 0)
1048                         return ret;
1049
1050                 pos += ret;
1051                 len -= ret;
1052         }
1053
1054         return 0;
1055 }
1056 EXPORT_SYMBOL_GPL(iomap_zero_range);
1057
1058 int
1059 iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
1060                 const struct iomap_ops *ops)
1061 {
1062         unsigned int blocksize = i_blocksize(inode);
1063         unsigned int off = pos & (blocksize - 1);
1064
1065         /* Block boundary? Nothing to do */
1066         if (!off)
1067                 return 0;
1068         return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
1069 }
1070 EXPORT_SYMBOL_GPL(iomap_truncate_page);
1071
1072 static loff_t
1073 iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
1074                 void *data, struct iomap *iomap)
1075 {
1076         struct page *page = data;
1077         int ret;
1078
1079         if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
1080                 ret = __block_write_begin_int(page, pos, length, NULL, iomap);
1081                 if (ret)
1082                         return ret;
1083                 block_commit_write(page, 0, length);
1084         } else {
1085                 WARN_ON_ONCE(!PageUptodate(page));
1086                 iomap_page_create(inode, page);
1087                 set_page_dirty(page);
1088         }
1089
1090         return length;
1091 }
1092
1093 vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
1094 {
1095         struct page *page = vmf->page;
1096         struct inode *inode = file_inode(vmf->vma->vm_file);
1097         unsigned long length;
1098         loff_t offset, size;
1099         ssize_t ret;
1100
1101         lock_page(page);
1102         size = i_size_read(inode);
1103         if ((page->mapping != inode->i_mapping) ||
1104             (page_offset(page) > size)) {
1105                 /* We overload EFAULT to mean page got truncated */
1106                 ret = -EFAULT;
1107                 goto out_unlock;
1108         }
1109
1110         /* page is wholly or partially inside EOF */
1111         if (((page->index + 1) << PAGE_SHIFT) > size)
1112                 length = offset_in_page(size);
1113         else
1114                 length = PAGE_SIZE;
1115
1116         offset = page_offset(page);
1117         while (length > 0) {
1118                 ret = iomap_apply(inode, offset, length,
1119                                 IOMAP_WRITE | IOMAP_FAULT, ops, page,
1120                                 iomap_page_mkwrite_actor);
1121                 if (unlikely(ret <= 0))
1122                         goto out_unlock;
1123                 offset += ret;
1124                 length -= ret;
1125         }
1126
1127         wait_for_stable_page(page);
1128         return VM_FAULT_LOCKED;
1129 out_unlock:
1130         unlock_page(page);
1131         return block_page_mkwrite_return(ret);
1132 }
1133 EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
1134
1135 struct fiemap_ctx {
1136         struct fiemap_extent_info *fi;
1137         struct iomap prev;
1138 };
1139
1140 static int iomap_to_fiemap(struct fiemap_extent_info *fi,
1141                 struct iomap *iomap, u32 flags)
1142 {
1143         switch (iomap->type) {
1144         case IOMAP_HOLE:
1145                 /* skip holes */
1146                 return 0;
1147         case IOMAP_DELALLOC:
1148                 flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN;
1149                 break;
1150         case IOMAP_MAPPED:
1151                 break;
1152         case IOMAP_UNWRITTEN:
1153                 flags |= FIEMAP_EXTENT_UNWRITTEN;
1154                 break;
1155         case IOMAP_INLINE:
1156                 flags |= FIEMAP_EXTENT_DATA_INLINE;
1157                 break;
1158         }
1159
1160         if (iomap->flags & IOMAP_F_MERGED)
1161                 flags |= FIEMAP_EXTENT_MERGED;
1162         if (iomap->flags & IOMAP_F_SHARED)
1163                 flags |= FIEMAP_EXTENT_SHARED;
1164
1165         return fiemap_fill_next_extent(fi, iomap->offset,
1166                         iomap->addr != IOMAP_NULL_ADDR ? iomap->addr : 0,
1167                         iomap->length, flags);
1168 }
1169
1170 static loff_t
1171 iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
1172                 struct iomap *iomap)
1173 {
1174         struct fiemap_ctx *ctx = data;
1175         loff_t ret = length;
1176
1177         if (iomap->type == IOMAP_HOLE)
1178                 return length;
1179
1180         ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0);
1181         ctx->prev = *iomap;
1182         switch (ret) {
1183         case 0:         /* success */
1184                 return length;
1185         case 1:         /* extent array full */
1186                 return 0;
1187         default:
1188                 return ret;
1189         }
1190 }
1191
1192 int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
1193                 loff_t start, loff_t len, const struct iomap_ops *ops)
1194 {
1195         struct fiemap_ctx ctx;
1196         loff_t ret;
1197
1198         memset(&ctx, 0, sizeof(ctx));
1199         ctx.fi = fi;
1200         ctx.prev.type = IOMAP_HOLE;
1201
1202         ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC);
1203         if (ret)
1204                 return ret;
1205
1206         if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
1207                 ret = filemap_write_and_wait(inode->i_mapping);
1208                 if (ret)
1209                         return ret;
1210         }
1211
1212         while (len > 0) {
1213                 ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
1214                                 iomap_fiemap_actor);
1215                 /* inode with no (attribute) mapping will give ENOENT */
1216                 if (ret == -ENOENT)
1217                         break;
1218                 if (ret < 0)
1219                         return ret;
1220                 if (ret == 0)
1221                         break;
1222
1223                 start += ret;
1224                 len -= ret;
1225         }
1226
1227         if (ctx.prev.type != IOMAP_HOLE) {
1228                 ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST);
1229                 if (ret < 0)
1230                         return ret;
1231         }
1232
1233         return 0;
1234 }
1235 EXPORT_SYMBOL_GPL(iomap_fiemap);
1236
1237 /*
1238  * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
1239  * Returns true if found and updates @lastoff to the offset in file.
1240  */
1241 static bool
1242 page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
1243                 int whence)
1244 {
1245         const struct address_space_operations *ops = inode->i_mapping->a_ops;
1246         unsigned int bsize = i_blocksize(inode), off;
1247         bool seek_data = whence == SEEK_DATA;
1248         loff_t poff = page_offset(page);
1249
1250         if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
1251                 return false;
1252
1253         if (*lastoff < poff) {
1254                 /*
1255                  * Last offset smaller than the start of the page means we found
1256                  * a hole:
1257                  */
1258                 if (whence == SEEK_HOLE)
1259                         return true;
1260                 *lastoff = poff;
1261         }
1262
1263         /*
1264          * Just check the page unless we can and should check block ranges:
1265          */
1266         if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)
1267                 return PageUptodate(page) == seek_data;
1268
1269         lock_page(page);
1270         if (unlikely(page->mapping != inode->i_mapping))
1271                 goto out_unlock_not_found;
1272
1273         for (off = 0; off < PAGE_SIZE; off += bsize) {
1274                 if (offset_in_page(*lastoff) >= off + bsize)
1275                         continue;
1276                 if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
1277                         unlock_page(page);
1278                         return true;
1279                 }
1280                 *lastoff = poff + off + bsize;
1281         }
1282
1283 out_unlock_not_found:
1284         unlock_page(page);
1285         return false;
1286 }
1287
1288 /*
1289  * Seek for SEEK_DATA / SEEK_HOLE in the page cache.
1290  *
1291  * Within unwritten extents, the page cache determines which parts are holes
1292  * and which are data: uptodate buffer heads count as data; everything else
1293  * counts as a hole.
1294  *
1295  * Returns the resulting offset on successs, and -ENOENT otherwise.
1296  */
1297 static loff_t
1298 page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
1299                 int whence)
1300 {
1301         pgoff_t index = offset >> PAGE_SHIFT;
1302         pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
1303         loff_t lastoff = offset;
1304         struct pagevec pvec;
1305
1306         if (length <= 0)
1307                 return -ENOENT;
1308
1309         pagevec_init(&pvec);
1310
1311         do {
1312                 unsigned nr_pages, i;
1313
1314                 nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
1315                                                 end - 1);
1316                 if (nr_pages == 0)
1317                         break;
1318
1319                 for (i = 0; i < nr_pages; i++) {
1320                         struct page *page = pvec.pages[i];
1321
1322                         if (page_seek_hole_data(inode, page, &lastoff, whence))
1323                                 goto check_range;
1324                         lastoff = page_offset(page) + PAGE_SIZE;
1325                 }
1326                 pagevec_release(&pvec);
1327         } while (index < end);
1328
1329         /* When no page at lastoff and we are not done, we found a hole. */
1330         if (whence != SEEK_HOLE)
1331                 goto not_found;
1332
1333 check_range:
1334         if (lastoff < offset + length)
1335                 goto out;
1336 not_found:
1337         lastoff = -ENOENT;
1338 out:
1339         pagevec_release(&pvec);
1340         return lastoff;
1341 }
1342
1343
1344 static loff_t
1345 iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
1346                       void *data, struct iomap *iomap)
1347 {
1348         switch (iomap->type) {
1349         case IOMAP_UNWRITTEN:
1350                 offset = page_cache_seek_hole_data(inode, offset, length,
1351                                                    SEEK_HOLE);
1352                 if (offset < 0)
1353                         return length;
1354                 /* fall through */
1355         case IOMAP_HOLE:
1356                 *(loff_t *)data = offset;
1357                 return 0;
1358         default:
1359                 return length;
1360         }
1361 }
1362
1363 loff_t
1364 iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
1365 {
1366         loff_t size = i_size_read(inode);
1367         loff_t length = size - offset;
1368         loff_t ret;
1369
1370         /* Nothing to be found before or beyond the end of the file. */
1371         if (offset < 0 || offset >= size)
1372                 return -ENXIO;
1373
1374         while (length > 0) {
1375                 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
1376                                   &offset, iomap_seek_hole_actor);
1377                 if (ret < 0)
1378                         return ret;
1379                 if (ret == 0)
1380                         break;
1381
1382                 offset += ret;
1383                 length -= ret;
1384         }
1385
1386         return offset;
1387 }
1388 EXPORT_SYMBOL_GPL(iomap_seek_hole);
1389
1390 static loff_t
1391 iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
1392                       void *data, struct iomap *iomap)
1393 {
1394         switch (iomap->type) {
1395         case IOMAP_HOLE:
1396                 return length;
1397         case IOMAP_UNWRITTEN:
1398                 offset = page_cache_seek_hole_data(inode, offset, length,
1399                                                    SEEK_DATA);
1400                 if (offset < 0)
1401                         return length;
1402                 /*FALLTHRU*/
1403         default:
1404                 *(loff_t *)data = offset;
1405                 return 0;
1406         }
1407 }
1408
1409 loff_t
1410 iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
1411 {
1412         loff_t size = i_size_read(inode);
1413         loff_t length = size - offset;
1414         loff_t ret;
1415
1416         /* Nothing to be found before or beyond the end of the file. */
1417         if (offset < 0 || offset >= size)
1418                 return -ENXIO;
1419
1420         while (length > 0) {
1421                 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
1422                                   &offset, iomap_seek_data_actor);
1423                 if (ret < 0)
1424                         return ret;
1425                 if (ret == 0)
1426                         break;
1427
1428                 offset += ret;
1429                 length -= ret;
1430         }
1431
1432         if (length <= 0)
1433                 return -ENXIO;
1434         return offset;
1435 }
1436 EXPORT_SYMBOL_GPL(iomap_seek_data);
1437
1438 /*
1439  * Private flags for iomap_dio, must not overlap with the public ones in
1440  * iomap.h:
1441  */
1442 #define IOMAP_DIO_WRITE_FUA     (1 << 28)
1443 #define IOMAP_DIO_NEED_SYNC     (1 << 29)
1444 #define IOMAP_DIO_WRITE         (1 << 30)
1445 #define IOMAP_DIO_DIRTY         (1 << 31)
1446
1447 struct iomap_dio {
1448         struct kiocb            *iocb;
1449         iomap_dio_end_io_t      *end_io;
1450         loff_t                  i_size;
1451         loff_t                  size;
1452         atomic_t                ref;
1453         unsigned                flags;
1454         int                     error;
1455         bool                    wait_for_completion;
1456
1457         union {
1458                 /* used during submission and for synchronous completion: */
1459                 struct {
1460                         struct iov_iter         *iter;
1461                         struct task_struct      *waiter;
1462                         struct request_queue    *last_queue;
1463                         blk_qc_t                cookie;
1464                 } submit;
1465
1466                 /* used for aio completion: */
1467                 struct {
1468                         struct work_struct      work;
1469                 } aio;
1470         };
1471 };
1472
1473 int iomap_dio_iopoll(struct kiocb *kiocb, bool spin)
1474 {
1475         struct request_queue *q = READ_ONCE(kiocb->private);
1476
1477         if (!q)
1478                 return 0;
1479         return blk_poll(q, READ_ONCE(kiocb->ki_cookie), spin);
1480 }
1481 EXPORT_SYMBOL_GPL(iomap_dio_iopoll);
1482
1483 static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
1484                 struct bio *bio)
1485 {
1486         atomic_inc(&dio->ref);
1487
1488         if (dio->iocb->ki_flags & IOCB_HIPRI)
1489                 bio_set_polled(bio, dio->iocb);
1490
1491         dio->submit.last_queue = bdev_get_queue(iomap->bdev);
1492         dio->submit.cookie = submit_bio(bio);
1493 }
1494
1495 static ssize_t iomap_dio_complete(struct iomap_dio *dio)
1496 {
1497         struct kiocb *iocb = dio->iocb;
1498         struct inode *inode = file_inode(iocb->ki_filp);
1499         loff_t offset = iocb->ki_pos;
1500         ssize_t ret;
1501
1502         if (dio->end_io) {
1503                 ret = dio->end_io(iocb,
1504                                 dio->error ? dio->error : dio->size,
1505                                 dio->flags);
1506         } else {
1507                 ret = dio->error;
1508         }
1509
1510         if (likely(!ret)) {
1511                 ret = dio->size;
1512                 /* check for short read */
1513                 if (offset + ret > dio->i_size &&
1514                     !(dio->flags & IOMAP_DIO_WRITE))
1515                         ret = dio->i_size - offset;
1516                 iocb->ki_pos += ret;
1517         }
1518
1519         /*
1520          * Try again to invalidate clean pages which might have been cached by
1521          * non-direct readahead, or faulted in by get_user_pages() if the source
1522          * of the write was an mmap'ed region of the file we're writing.  Either
1523          * one is a pretty crazy thing to do, so we don't support it 100%.  If
1524          * this invalidation fails, tough, the write still worked...
1525          *
1526          * And this page cache invalidation has to be after dio->end_io(), as
1527          * some filesystems convert unwritten extents to real allocations in
1528          * end_io() when necessary, otherwise a racing buffer read would cache
1529          * zeros from unwritten extents.
1530          */
1531         if (!dio->error &&
1532             (dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) {
1533                 int err;
1534                 err = invalidate_inode_pages2_range(inode->i_mapping,
1535                                 offset >> PAGE_SHIFT,
1536                                 (offset + dio->size - 1) >> PAGE_SHIFT);
1537                 if (err)
1538                         dio_warn_stale_pagecache(iocb->ki_filp);
1539         }
1540
1541         /*
1542          * If this is a DSYNC write, make sure we push it to stable storage now
1543          * that we've written data.
1544          */
1545         if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
1546                 ret = generic_write_sync(iocb, ret);
1547
1548         inode_dio_end(file_inode(iocb->ki_filp));
1549         kfree(dio);
1550
1551         return ret;
1552 }
1553
1554 static void iomap_dio_complete_work(struct work_struct *work)
1555 {
1556         struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
1557         struct kiocb *iocb = dio->iocb;
1558
1559         iocb->ki_complete(iocb, iomap_dio_complete(dio), 0);
1560 }
1561
1562 /*
1563  * Set an error in the dio if none is set yet.  We have to use cmpxchg
1564  * as the submission context and the completion context(s) can race to
1565  * update the error.
1566  */
1567 static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
1568 {
1569         cmpxchg(&dio->error, 0, ret);
1570 }
1571
1572 static void iomap_dio_bio_end_io(struct bio *bio)
1573 {
1574         struct iomap_dio *dio = bio->bi_private;
1575         bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
1576
1577         if (bio->bi_status)
1578                 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
1579
1580         if (atomic_dec_and_test(&dio->ref)) {
1581                 if (dio->wait_for_completion) {
1582                         struct task_struct *waiter = dio->submit.waiter;
1583                         WRITE_ONCE(dio->submit.waiter, NULL);
1584                         blk_wake_io_task(waiter);
1585                 } else if (dio->flags & IOMAP_DIO_WRITE) {
1586                         struct inode *inode = file_inode(dio->iocb->ki_filp);
1587
1588                         INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
1589                         queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
1590                 } else {
1591                         iomap_dio_complete_work(&dio->aio.work);
1592                 }
1593         }
1594
1595         if (should_dirty) {
1596                 bio_check_pages_dirty(bio);
1597         } else {
1598                 if (!bio_flagged(bio, BIO_NO_PAGE_REF)) {
1599                         struct bvec_iter_all iter_all;
1600                         struct bio_vec *bvec;
1601
1602                         bio_for_each_segment_all(bvec, bio, iter_all)
1603                                 put_page(bvec->bv_page);
1604                 }
1605                 bio_put(bio);
1606         }
1607 }
1608
1609 static void
1610 iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
1611                 unsigned len)
1612 {
1613         struct page *page = ZERO_PAGE(0);
1614         int flags = REQ_SYNC | REQ_IDLE;
1615         struct bio *bio;
1616
1617         bio = bio_alloc(GFP_KERNEL, 1);
1618         bio_set_dev(bio, iomap->bdev);
1619         bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
1620         bio->bi_private = dio;
1621         bio->bi_end_io = iomap_dio_bio_end_io;
1622
1623         get_page(page);
1624         __bio_add_page(bio, page, len, 0);
1625         bio_set_op_attrs(bio, REQ_OP_WRITE, flags);
1626         iomap_dio_submit_bio(dio, iomap, bio);
1627 }
1628
1629 static loff_t
1630 iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
1631                 struct iomap_dio *dio, struct iomap *iomap)
1632 {
1633         unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
1634         unsigned int fs_block_size = i_blocksize(inode), pad;
1635         unsigned int align = iov_iter_alignment(dio->submit.iter);
1636         struct iov_iter iter;
1637         struct bio *bio;
1638         bool need_zeroout = false;
1639         bool use_fua = false;
1640         int nr_pages, ret = 0;
1641         size_t copied = 0;
1642
1643         if ((pos | length | align) & ((1 << blkbits) - 1))
1644                 return -EINVAL;
1645
1646         if (iomap->type == IOMAP_UNWRITTEN) {
1647                 dio->flags |= IOMAP_DIO_UNWRITTEN;
1648                 need_zeroout = true;
1649         }
1650
1651         if (iomap->flags & IOMAP_F_SHARED)
1652                 dio->flags |= IOMAP_DIO_COW;
1653
1654         if (iomap->flags & IOMAP_F_NEW) {
1655                 need_zeroout = true;
1656         } else if (iomap->type == IOMAP_MAPPED) {
1657                 /*
1658                  * Use a FUA write if we need datasync semantics, this is a pure
1659                  * data IO that doesn't require any metadata updates (including
1660                  * after IO completion such as unwritten extent conversion) and
1661                  * the underlying device supports FUA. This allows us to avoid
1662                  * cache flushes on IO completion.
1663                  */
1664                 if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) &&
1665                     (dio->flags & IOMAP_DIO_WRITE_FUA) &&
1666                     blk_queue_fua(bdev_get_queue(iomap->bdev)))
1667                         use_fua = true;
1668         }
1669
1670         /*
1671          * Operate on a partial iter trimmed to the extent we were called for.
1672          * We'll update the iter in the dio once we're done with this extent.
1673          */
1674         iter = *dio->submit.iter;
1675         iov_iter_truncate(&iter, length);
1676
1677         nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
1678         if (nr_pages <= 0)
1679                 return nr_pages;
1680
1681         if (need_zeroout) {
1682                 /* zero out from the start of the block to the write offset */
1683                 pad = pos & (fs_block_size - 1);
1684                 if (pad)
1685                         iomap_dio_zero(dio, iomap, pos - pad, pad);
1686         }
1687
1688         do {
1689                 size_t n;
1690                 if (dio->error) {
1691                         iov_iter_revert(dio->submit.iter, copied);
1692                         return 0;
1693                 }
1694
1695                 bio = bio_alloc(GFP_KERNEL, nr_pages);
1696                 bio_set_dev(bio, iomap->bdev);
1697                 bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
1698                 bio->bi_write_hint = dio->iocb->ki_hint;
1699                 bio->bi_ioprio = dio->iocb->ki_ioprio;
1700                 bio->bi_private = dio;
1701                 bio->bi_end_io = iomap_dio_bio_end_io;
1702
1703                 ret = bio_iov_iter_get_pages(bio, &iter);
1704                 if (unlikely(ret)) {
1705                         /*
1706                          * We have to stop part way through an IO. We must fall
1707                          * through to the sub-block tail zeroing here, otherwise
1708                          * this short IO may expose stale data in the tail of
1709                          * the block we haven't written data to.
1710                          */
1711                         bio_put(bio);
1712                         goto zero_tail;
1713                 }
1714
1715                 n = bio->bi_iter.bi_size;
1716                 if (dio->flags & IOMAP_DIO_WRITE) {
1717                         bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
1718                         if (use_fua)
1719                                 bio->bi_opf |= REQ_FUA;
1720                         else
1721                                 dio->flags &= ~IOMAP_DIO_WRITE_FUA;
1722                         task_io_account_write(n);
1723                 } else {
1724                         bio->bi_opf = REQ_OP_READ;
1725                         if (dio->flags & IOMAP_DIO_DIRTY)
1726                                 bio_set_pages_dirty(bio);
1727                 }
1728
1729                 iov_iter_advance(dio->submit.iter, n);
1730
1731                 dio->size += n;
1732                 pos += n;
1733                 copied += n;
1734
1735                 nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
1736                 iomap_dio_submit_bio(dio, iomap, bio);
1737         } while (nr_pages);
1738
1739         /*
1740          * We need to zeroout the tail of a sub-block write if the extent type
1741          * requires zeroing or the write extends beyond EOF. If we don't zero
1742          * the block tail in the latter case, we can expose stale data via mmap
1743          * reads of the EOF block.
1744          */
1745 zero_tail:
1746         if (need_zeroout ||
1747             ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
1748                 /* zero out from the end of the write to the end of the block */
1749                 pad = pos & (fs_block_size - 1);
1750                 if (pad)
1751                         iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
1752         }
1753         return copied ? copied : ret;
1754 }
1755
1756 static loff_t
1757 iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio)
1758 {
1759         length = iov_iter_zero(length, dio->submit.iter);
1760         dio->size += length;
1761         return length;
1762 }
1763
1764 static loff_t
1765 iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
1766                 struct iomap_dio *dio, struct iomap *iomap)
1767 {
1768         struct iov_iter *iter = dio->submit.iter;
1769         size_t copied;
1770
1771         BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data));
1772
1773         if (dio->flags & IOMAP_DIO_WRITE) {
1774                 loff_t size = inode->i_size;
1775
1776                 if (pos > size)
1777                         memset(iomap->inline_data + size, 0, pos - size);
1778                 copied = copy_from_iter(iomap->inline_data + pos, length, iter);
1779                 if (copied) {
1780                         if (pos + copied > size)
1781                                 i_size_write(inode, pos + copied);
1782                         mark_inode_dirty(inode);
1783                 }
1784         } else {
1785                 copied = copy_to_iter(iomap->inline_data + pos, length, iter);
1786         }
1787         dio->size += copied;
1788         return copied;
1789 }
1790
1791 static loff_t
1792 iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
1793                 void *data, struct iomap *iomap)
1794 {
1795         struct iomap_dio *dio = data;
1796
1797         switch (iomap->type) {
1798         case IOMAP_HOLE:
1799                 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
1800                         return -EIO;
1801                 return iomap_dio_hole_actor(length, dio);
1802         case IOMAP_UNWRITTEN:
1803                 if (!(dio->flags & IOMAP_DIO_WRITE))
1804                         return iomap_dio_hole_actor(length, dio);
1805                 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
1806         case IOMAP_MAPPED:
1807                 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
1808         case IOMAP_INLINE:
1809                 return iomap_dio_inline_actor(inode, pos, length, dio, iomap);
1810         default:
1811                 WARN_ON_ONCE(1);
1812                 return -EIO;
1813         }
1814 }
1815
1816 /*
1817  * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
1818  * is being issued as AIO or not.  This allows us to optimise pure data writes
1819  * to use REQ_FUA rather than requiring generic_write_sync() to issue a
1820  * REQ_FLUSH post write. This is slightly tricky because a single request here
1821  * can be mapped into multiple disjoint IOs and only a subset of the IOs issued
1822  * may be pure data writes. In that case, we still need to do a full data sync
1823  * completion.
1824  */
1825 ssize_t
1826 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
1827                 const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
1828 {
1829         struct address_space *mapping = iocb->ki_filp->f_mapping;
1830         struct inode *inode = file_inode(iocb->ki_filp);
1831         size_t count = iov_iter_count(iter);
1832         loff_t pos = iocb->ki_pos, start = pos;
1833         loff_t end = iocb->ki_pos + count - 1, ret = 0;
1834         unsigned int flags = IOMAP_DIRECT;
1835         bool wait_for_completion = is_sync_kiocb(iocb);
1836         struct blk_plug plug;
1837         struct iomap_dio *dio;
1838
1839         lockdep_assert_held(&inode->i_rwsem);
1840
1841         if (!count)
1842                 return 0;
1843
1844         dio = kmalloc(sizeof(*dio), GFP_KERNEL);
1845         if (!dio)
1846                 return -ENOMEM;
1847
1848         dio->iocb = iocb;
1849         atomic_set(&dio->ref, 1);
1850         dio->size = 0;
1851         dio->i_size = i_size_read(inode);
1852         dio->end_io = end_io;
1853         dio->error = 0;
1854         dio->flags = 0;
1855
1856         dio->submit.iter = iter;
1857         dio->submit.waiter = current;
1858         dio->submit.cookie = BLK_QC_T_NONE;
1859         dio->submit.last_queue = NULL;
1860
1861         if (iov_iter_rw(iter) == READ) {
1862                 if (pos >= dio->i_size)
1863                         goto out_free_dio;
1864
1865                 if (iter_is_iovec(iter) && iov_iter_rw(iter) == READ)
1866                         dio->flags |= IOMAP_DIO_DIRTY;
1867         } else {
1868                 flags |= IOMAP_WRITE;
1869                 dio->flags |= IOMAP_DIO_WRITE;
1870
1871                 /* for data sync or sync, we need sync completion processing */
1872                 if (iocb->ki_flags & IOCB_DSYNC)
1873                         dio->flags |= IOMAP_DIO_NEED_SYNC;
1874
1875                 /*
1876                  * For datasync only writes, we optimistically try using FUA for
1877                  * this IO.  Any non-FUA write that occurs will clear this flag,
1878                  * hence we know before completion whether a cache flush is
1879                  * necessary.
1880                  */
1881                 if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC)
1882                         dio->flags |= IOMAP_DIO_WRITE_FUA;
1883         }
1884
1885         if (iocb->ki_flags & IOCB_NOWAIT) {
1886                 if (filemap_range_has_page(mapping, start, end)) {
1887                         ret = -EAGAIN;
1888                         goto out_free_dio;
1889                 }
1890                 flags |= IOMAP_NOWAIT;
1891         }
1892
1893         ret = filemap_write_and_wait_range(mapping, start, end);
1894         if (ret)
1895                 goto out_free_dio;
1896
1897         /*
1898          * Try to invalidate cache pages for the range we're direct
1899          * writing.  If this invalidation fails, tough, the write will
1900          * still work, but racing two incompatible write paths is a
1901          * pretty crazy thing to do, so we don't support it 100%.
1902          */
1903         ret = invalidate_inode_pages2_range(mapping,
1904                         start >> PAGE_SHIFT, end >> PAGE_SHIFT);
1905         if (ret)
1906                 dio_warn_stale_pagecache(iocb->ki_filp);
1907         ret = 0;
1908
1909         if (iov_iter_rw(iter) == WRITE && !wait_for_completion &&
1910             !inode->i_sb->s_dio_done_wq) {
1911                 ret = sb_init_dio_done_wq(inode->i_sb);
1912                 if (ret < 0)
1913                         goto out_free_dio;
1914         }
1915
1916         inode_dio_begin(inode);
1917
1918         blk_start_plug(&plug);
1919         do {
1920                 ret = iomap_apply(inode, pos, count, flags, ops, dio,
1921                                 iomap_dio_actor);
1922                 if (ret <= 0) {
1923                         /* magic error code to fall back to buffered I/O */
1924                         if (ret == -ENOTBLK) {
1925                                 wait_for_completion = true;
1926                                 ret = 0;
1927                         }
1928                         break;
1929                 }
1930                 pos += ret;
1931
1932                 if (iov_iter_rw(iter) == READ && pos >= dio->i_size)
1933                         break;
1934         } while ((count = iov_iter_count(iter)) > 0);
1935         blk_finish_plug(&plug);
1936
1937         if (ret < 0)
1938                 iomap_dio_set_error(dio, ret);
1939
1940         /*
1941          * If all the writes we issued were FUA, we don't need to flush the
1942          * cache on IO completion. Clear the sync flag for this case.
1943          */
1944         if (dio->flags & IOMAP_DIO_WRITE_FUA)
1945                 dio->flags &= ~IOMAP_DIO_NEED_SYNC;
1946
1947         WRITE_ONCE(iocb->ki_cookie, dio->submit.cookie);
1948         WRITE_ONCE(iocb->private, dio->submit.last_queue);
1949
1950         /*
1951          * We are about to drop our additional submission reference, which
1952          * might be the last reference to the dio.  There are three three
1953          * different ways we can progress here:
1954          *
1955          *  (a) If this is the last reference we will always complete and free
1956          *      the dio ourselves.
1957          *  (b) If this is not the last reference, and we serve an asynchronous
1958          *      iocb, we must never touch the dio after the decrement, the
1959          *      I/O completion handler will complete and free it.
1960          *  (c) If this is not the last reference, but we serve a synchronous
1961          *      iocb, the I/O completion handler will wake us up on the drop
1962          *      of the final reference, and we will complete and free it here
1963          *      after we got woken by the I/O completion handler.
1964          */
1965         dio->wait_for_completion = wait_for_completion;
1966         if (!atomic_dec_and_test(&dio->ref)) {
1967                 if (!wait_for_completion)
1968                         return -EIOCBQUEUED;
1969
1970                 for (;;) {
1971                         set_current_state(TASK_UNINTERRUPTIBLE);
1972                         if (!READ_ONCE(dio->submit.waiter))
1973                                 break;
1974
1975                         if (!(iocb->ki_flags & IOCB_HIPRI) ||
1976                             !dio->submit.last_queue ||
1977                             !blk_poll(dio->submit.last_queue,
1978                                          dio->submit.cookie, true))
1979                                 io_schedule();
1980                 }
1981                 __set_current_state(TASK_RUNNING);
1982         }
1983
1984         return iomap_dio_complete(dio);
1985
1986 out_free_dio:
1987         kfree(dio);
1988         return ret;
1989 }
1990 EXPORT_SYMBOL_GPL(iomap_dio_rw);
1991
1992 /* Swapfile activation */
1993
1994 #ifdef CONFIG_SWAP
1995 struct iomap_swapfile_info {
1996         struct iomap iomap;             /* accumulated iomap */
1997         struct swap_info_struct *sis;
1998         uint64_t lowest_ppage;          /* lowest physical addr seen (pages) */
1999         uint64_t highest_ppage;         /* highest physical addr seen (pages) */
2000         unsigned long nr_pages;         /* number of pages collected */
2001         int nr_extents;                 /* extent count */
2002 };
2003
2004 /*
2005  * Collect physical extents for this swap file.  Physical extents reported to
2006  * the swap code must be trimmed to align to a page boundary.  The logical
2007  * offset within the file is irrelevant since the swapfile code maps logical
2008  * page numbers of the swap device to the physical page-aligned extents.
2009  */
2010 static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
2011 {
2012         struct iomap *iomap = &isi->iomap;
2013         unsigned long nr_pages;
2014         uint64_t first_ppage;
2015         uint64_t first_ppage_reported;
2016         uint64_t next_ppage;
2017         int error;
2018
2019         /*
2020          * Round the start up and the end down so that the physical
2021          * extent aligns to a page boundary.
2022          */
2023         first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT;
2024         next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >>
2025                         PAGE_SHIFT;
2026
2027         /* Skip too-short physical extents. */
2028         if (first_ppage >= next_ppage)
2029                 return 0;
2030         nr_pages = next_ppage - first_ppage;
2031
2032         /*
2033          * Calculate how much swap space we're adding; the first page contains
2034          * the swap header and doesn't count.  The mm still wants that first
2035          * page fed to add_swap_extent, however.
2036          */
2037         first_ppage_reported = first_ppage;
2038         if (iomap->offset == 0)
2039                 first_ppage_reported++;
2040         if (isi->lowest_ppage > first_ppage_reported)
2041                 isi->lowest_ppage = first_ppage_reported;
2042         if (isi->highest_ppage < (next_ppage - 1))
2043                 isi->highest_ppage = next_ppage - 1;
2044
2045         /* Add extent, set up for the next call. */
2046         error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage);
2047         if (error < 0)
2048                 return error;
2049         isi->nr_extents += error;
2050         isi->nr_pages += nr_pages;
2051         return 0;
2052 }
2053
2054 /*
2055  * Accumulate iomaps for this swap file.  We have to accumulate iomaps because
2056  * swap only cares about contiguous page-aligned physical extents and makes no
2057  * distinction between written and unwritten extents.
2058  */
2059 static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
2060                 loff_t count, void *data, struct iomap *iomap)
2061 {
2062         struct iomap_swapfile_info *isi = data;
2063         int error;
2064
2065         switch (iomap->type) {
2066         case IOMAP_MAPPED:
2067         case IOMAP_UNWRITTEN:
2068                 /* Only real or unwritten extents. */
2069                 break;
2070         case IOMAP_INLINE:
2071                 /* No inline data. */
2072                 pr_err("swapon: file is inline\n");
2073                 return -EINVAL;
2074         default:
2075                 pr_err("swapon: file has unallocated extents\n");
2076                 return -EINVAL;
2077         }
2078
2079         /* No uncommitted metadata or shared blocks. */
2080         if (iomap->flags & IOMAP_F_DIRTY) {
2081                 pr_err("swapon: file is not committed\n");
2082                 return -EINVAL;
2083         }
2084         if (iomap->flags & IOMAP_F_SHARED) {
2085                 pr_err("swapon: file has shared extents\n");
2086                 return -EINVAL;
2087         }
2088
2089         /* Only one bdev per swap file. */
2090         if (iomap->bdev != isi->sis->bdev) {
2091                 pr_err("swapon: file is on multiple devices\n");
2092                 return -EINVAL;
2093         }
2094
2095         if (isi->iomap.length == 0) {
2096                 /* No accumulated extent, so just store it. */
2097                 memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
2098         } else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
2099                 /* Append this to the accumulated extent. */
2100                 isi->iomap.length += iomap->length;
2101         } else {
2102                 /* Otherwise, add the retained iomap and store this one. */
2103                 error = iomap_swapfile_add_extent(isi);
2104                 if (error)
2105                         return error;
2106                 memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
2107         }
2108         return count;
2109 }
2110
2111 /*
2112  * Iterate a swap file's iomaps to construct physical extents that can be
2113  * passed to the swapfile subsystem.
2114  */
2115 int iomap_swapfile_activate(struct swap_info_struct *sis,
2116                 struct file *swap_file, sector_t *pagespan,
2117                 const struct iomap_ops *ops)
2118 {
2119         struct iomap_swapfile_info isi = {
2120                 .sis = sis,
2121                 .lowest_ppage = (sector_t)-1ULL,
2122         };
2123         struct address_space *mapping = swap_file->f_mapping;
2124         struct inode *inode = mapping->host;
2125         loff_t pos = 0;
2126         loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE);
2127         loff_t ret;
2128
2129         /*
2130          * Persist all file mapping metadata so that we won't have any
2131          * IOMAP_F_DIRTY iomaps.
2132          */
2133         ret = vfs_fsync(swap_file, 1);
2134         if (ret)
2135                 return ret;
2136
2137         while (len > 0) {
2138                 ret = iomap_apply(inode, pos, len, IOMAP_REPORT,
2139                                 ops, &isi, iomap_swapfile_activate_actor);
2140                 if (ret <= 0)
2141                         return ret;
2142
2143                 pos += ret;
2144                 len -= ret;
2145         }
2146
2147         if (isi.iomap.length) {
2148                 ret = iomap_swapfile_add_extent(&isi);
2149                 if (ret)
2150                         return ret;
2151         }
2152
2153         *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
2154         sis->max = isi.nr_pages;
2155         sis->pages = isi.nr_pages - 1;
2156         sis->highest_bit = isi.nr_pages - 1;
2157         return isi.nr_extents;
2158 }
2159 EXPORT_SYMBOL_GPL(iomap_swapfile_activate);
2160 #endif /* CONFIG_SWAP */
2161
2162 static loff_t
2163 iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
2164                 void *data, struct iomap *iomap)
2165 {
2166         sector_t *bno = data, addr;
2167
2168         if (iomap->type == IOMAP_MAPPED) {
2169                 addr = (pos - iomap->offset + iomap->addr) >> inode->i_blkbits;
2170                 if (addr > INT_MAX)
2171                         WARN(1, "would truncate bmap result\n");
2172                 else
2173                         *bno = addr;
2174         }
2175         return 0;
2176 }
2177
2178 /* legacy ->bmap interface.  0 is the error return (!) */
2179 sector_t
2180 iomap_bmap(struct address_space *mapping, sector_t bno,
2181                 const struct iomap_ops *ops)
2182 {
2183         struct inode *inode = mapping->host;
2184         loff_t pos = bno << inode->i_blkbits;
2185         unsigned blocksize = i_blocksize(inode);
2186
2187         if (filemap_write_and_wait(mapping))
2188                 return 0;
2189
2190         bno = 0;
2191         iomap_apply(inode, pos, blocksize, 0, ops, &bno, iomap_bmap_actor);
2192         return bno;
2193 }
2194 EXPORT_SYMBOL_GPL(iomap_bmap);