git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/fs-io-buffered.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #ifndef NO_BCACHEFS_FS
   3
   4 #include "bcachefs.h"
   5 #include "alloc_foreground.h"
   6 #include "bkey_buf.h"
   7 #include "fs-io.h"
   8 #include "fs-io-buffered.h"
   9 #include "fs-io-direct.h"
  10 #include "fs-io-pagecache.h"
  11 #include "io_read.h"
  12 #include "io_write.h"
  13
  14 #include <linux/backing-dev.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/writeback.h>
  17
  18 static inline bool bio_full(struct bio *bio, unsigned len)
  19 {
  20         if (bio->bi_vcnt >= bio->bi_max_vecs)
  21                 return true;
  22         if (bio->bi_iter.bi_size > UINT_MAX - len)
  23                 return true;
  24         return false;
  25 }
  26
  27 /* readpage(s): */
  28
  29 static void bch2_readpages_end_io(struct bio *bio)
  30 {
  31         struct folio_iter fi;
  32
  33         bio_for_each_folio_all(fi, bio) {
  34                 if (!bio->bi_status) {
  35                         folio_mark_uptodate(fi.folio);
  36                 } else {
  37                         folio_clear_uptodate(fi.folio);
  38                         folio_set_error(fi.folio);
  39                 }
  40                 folio_unlock(fi.folio);
  41         }
  42
  43         bio_put(bio);
  44 }
  45
  46 struct readpages_iter {
  47         struct address_space    *mapping;
  48         unsigned                idx;
  49         folios                  folios;
  50 };
  51
  52 static int readpages_iter_init(struct readpages_iter *iter,
  53                                struct readahead_control *ractl)
  54 {
  55         struct folio *folio;
  56
  57         *iter = (struct readpages_iter) { ractl->mapping };
  58
  59         while ((folio = __readahead_folio(ractl))) {
  60                 if (!bch2_folio_create(folio, GFP_KERNEL) ||
  61                     darray_push(&iter->folios, folio)) {
  62                         bch2_folio_release(folio);
  63                         ractl->_nr_pages += folio_nr_pages(folio);
  64                         ractl->_index -= folio_nr_pages(folio);
  65                         return iter->folios.nr ? 0 : -ENOMEM;
  66                 }
  67
  68                 folio_put(folio);
  69         }
  70
  71         return 0;
  72 }
  73
  74 static inline struct folio *readpage_iter_peek(struct readpages_iter *iter)
  75 {
  76         if (iter->idx >= iter->folios.nr)
  77                 return NULL;
  78         return iter->folios.data[iter->idx];
  79 }
  80
  81 static inline void readpage_iter_advance(struct readpages_iter *iter)
  82 {
  83         iter->idx++;
  84 }
  85
  86 static bool extent_partial_reads_expensive(struct bkey_s_c k)
  87 {
  88         struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
  89         struct bch_extent_crc_unpacked crc;
  90         const union bch_extent_entry *i;
  91
  92         bkey_for_each_crc(k.k, ptrs, crc, i)
  93                 if (crc.csum_type || crc.compression_type)
  94                         return true;
  95         return false;
  96 }
  97
  98 static int readpage_bio_extend(struct btree_trans *trans,
  99                                struct readpages_iter *iter,
 100                                struct bio *bio,
 101                                unsigned sectors_this_extent,
 102                                bool get_more)
 103 {
 104         /* Don't hold btree locks while allocating memory: */
 105         bch2_trans_unlock(trans);
 106
 107         while (bio_sectors(bio) < sectors_this_extent &&
 108                bio->bi_vcnt < bio->bi_max_vecs) {
 109                 struct folio *folio = readpage_iter_peek(iter);
 110                 int ret;
 111
 112                 if (folio) {
 113                         readpage_iter_advance(iter);
 114                 } else {
 115                         pgoff_t folio_offset = bio_end_sector(bio) >> PAGE_SECTORS_SHIFT;
 116
 117                         if (!get_more)
 118                                 break;
 119
 120                         folio = xa_load(&iter->mapping->i_pages, folio_offset);
 121                         if (folio && !xa_is_value(folio))
 122                                 break;
 123
 124                         folio = filemap_alloc_folio(readahead_gfp_mask(iter->mapping), 0);
 125                         if (!folio)
 126                                 break;
 127
 128                         if (!__bch2_folio_create(folio, GFP_KERNEL)) {
 129                                 folio_put(folio);
 130                                 break;
 131                         }
 132
 133                         ret = filemap_add_folio(iter->mapping, folio, folio_offset, GFP_KERNEL);
 134                         if (ret) {
 135                                 __bch2_folio_release(folio);
 136                                 folio_put(folio);
 137                                 break;
 138                         }
 139
 140                         folio_put(folio);
 141                 }
 142
 143                 BUG_ON(folio_sector(folio) != bio_end_sector(bio));
 144
 145                 BUG_ON(!bio_add_folio(bio, folio, folio_size(folio), 0));
 146         }
 147
 148         return bch2_trans_relock(trans);
 149 }
 150
 151 static void bchfs_read(struct btree_trans *trans,
 152                        struct bch_read_bio *rbio,
 153                        subvol_inum inum,
 154                        struct readpages_iter *readpages_iter)
 155 {
 156         struct bch_fs *c = trans->c;
 157         struct btree_iter iter;
 158         struct bkey_buf sk;
 159         int flags = BCH_READ_RETRY_IF_STALE|
 160                 BCH_READ_MAY_PROMOTE;
 161         u32 snapshot;
 162         int ret = 0;
 163
 164         rbio->c = c;
 165         rbio->start_time = local_clock();
 166         rbio->subvol = inum.subvol;
 167
 168         bch2_bkey_buf_init(&sk);
 169 retry:
 170         bch2_trans_begin(trans);
 171         iter = (struct btree_iter) { NULL };
 172
 173         ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 174         if (ret)
 175                 goto err;
 176
 177         bch2_trans_iter_init(trans, &iter, BTREE_ID_extents,
 178                              SPOS(inum.inum, rbio->bio.bi_iter.bi_sector, snapshot),
 179                              BTREE_ITER_SLOTS);
 180         while (1) {
 181                 struct bkey_s_c k;
 182                 unsigned bytes, sectors, offset_into_extent;
 183                 enum btree_id data_btree = BTREE_ID_extents;
 184
 185                 /*
 186                  * read_extent -> io_time_reset may cause a transaction restart
 187                  * without returning an error, we need to check for that here:
 188                  */
 189                 ret = bch2_trans_relock(trans);
 190                 if (ret)
 191                         break;
 192
 193                 bch2_btree_iter_set_pos(&iter,
 194                                 POS(inum.inum, rbio->bio.bi_iter.bi_sector));
 195
 196                 k = bch2_btree_iter_peek_slot(&iter);
 197                 ret = bkey_err(k);
 198                 if (ret)
 199                         break;
 200
 201                 offset_into_extent = iter.pos.offset -
 202                         bkey_start_offset(k.k);
 203                 sectors = k.k->size - offset_into_extent;
 204
 205                 bch2_bkey_buf_reassemble(&sk, c, k);
 206
 207                 ret = bch2_read_indirect_extent(trans, &data_btree,
 208                                         &offset_into_extent, &sk);
 209                 if (ret)
 210                         break;
 211
 212                 k = bkey_i_to_s_c(sk.k);
 213
 214                 sectors = min(sectors, k.k->size - offset_into_extent);
 215
 216                 if (readpages_iter) {
 217                         ret = readpage_bio_extend(trans, readpages_iter, &rbio->bio, sectors,
 218                                                   extent_partial_reads_expensive(k));
 219                         if (ret)
 220                                 break;
 221                 }
 222
 223                 bytes = min(sectors, bio_sectors(&rbio->bio)) << 9;
 224                 swap(rbio->bio.bi_iter.bi_size, bytes);
 225
 226                 if (rbio->bio.bi_iter.bi_size == bytes)
 227                         flags |= BCH_READ_LAST_FRAGMENT;
 228
 229                 bch2_bio_page_state_set(&rbio->bio, k);
 230
 231                 bch2_read_extent(trans, rbio, iter.pos,
 232                                  data_btree, k, offset_into_extent, flags);
 233
 234                 if (flags & BCH_READ_LAST_FRAGMENT)
 235                         break;
 236
 237                 swap(rbio->bio.bi_iter.bi_size, bytes);
 238                 bio_advance(&rbio->bio, bytes);
 239
 240                 ret = btree_trans_too_many_iters(trans);
 241                 if (ret)
 242                         break;
 243         }
 244 err:
 245         bch2_trans_iter_exit(trans, &iter);
 246
 247         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 248                 goto retry;
 249
 250         if (ret) {
 251                 bch_err_inum_offset_ratelimited(c,
 252                                 iter.pos.inode,
 253                                 iter.pos.offset << 9,
 254                                 "read error %i from btree lookup", ret);
 255                 rbio->bio.bi_status = BLK_STS_IOERR;
 256                 bio_endio(&rbio->bio);
 257         }
 258
 259         bch2_bkey_buf_exit(&sk, c);
 260 }
 261
 262 void bch2_readahead(struct readahead_control *ractl)
 263 {
 264         struct bch_inode_info *inode = to_bch_ei(ractl->mapping->host);
 265         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 266         struct bch_io_opts opts;
 267         struct btree_trans *trans = bch2_trans_get(c);
 268         struct folio *folio;
 269         struct readpages_iter readpages_iter;
 270
 271         bch2_inode_opts_get(&opts, c, &inode->ei_inode);
 272
 273         int ret = readpages_iter_init(&readpages_iter, ractl);
 274         if (ret)
 275                 return;
 276
 277         bch2_pagecache_add_get(inode);
 278
 279         while ((folio = readpage_iter_peek(&readpages_iter))) {
 280                 unsigned n = min_t(unsigned,
 281                                    readpages_iter.folios.nr -
 282                                    readpages_iter.idx,
 283                                    BIO_MAX_VECS);
 284                 struct bch_read_bio *rbio =
 285                         rbio_init(bio_alloc_bioset(NULL, n, REQ_OP_READ,
 286                                                    GFP_KERNEL, &c->bio_read),
 287                                   opts);
 288
 289                 readpage_iter_advance(&readpages_iter);
 290
 291                 rbio->bio.bi_iter.bi_sector = folio_sector(folio);
 292                 rbio->bio.bi_end_io = bch2_readpages_end_io;
 293                 BUG_ON(!bio_add_folio(&rbio->bio, folio, folio_size(folio), 0));
 294
 295                 bchfs_read(trans, rbio, inode_inum(inode),
 296                            &readpages_iter);
 297                 bch2_trans_unlock(trans);
 298         }
 299
 300         bch2_pagecache_add_put(inode);
 301
 302         bch2_trans_put(trans);
 303         darray_exit(&readpages_iter.folios);
 304 }
 305
 306 static void __bchfs_readfolio(struct bch_fs *c, struct bch_read_bio *rbio,
 307                              subvol_inum inum, struct folio *folio)
 308 {
 309         bch2_folio_create(folio, __GFP_NOFAIL);
 310
 311         rbio->bio.bi_opf = REQ_OP_READ|REQ_SYNC;
 312         rbio->bio.bi_iter.bi_sector = folio_sector(folio);
 313         BUG_ON(!bio_add_folio(&rbio->bio, folio, folio_size(folio), 0));
 314
 315         bch2_trans_run(c, (bchfs_read(trans, rbio, inum, NULL), 0));
 316 }
 317
 318 static void bch2_read_single_folio_end_io(struct bio *bio)
 319 {
 320         complete(bio->bi_private);
 321 }
 322
 323 int bch2_read_single_folio(struct folio *folio, struct address_space *mapping)
 324 {
 325         struct bch_inode_info *inode = to_bch_ei(mapping->host);
 326         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 327         struct bch_read_bio *rbio;
 328         struct bch_io_opts opts;
 329         int ret;
 330         DECLARE_COMPLETION_ONSTACK(done);
 331
 332         bch2_inode_opts_get(&opts, c, &inode->ei_inode);
 333
 334         rbio = rbio_init(bio_alloc_bioset(NULL, 1, REQ_OP_READ, GFP_KERNEL, &c->bio_read),
 335                          opts);
 336         rbio->bio.bi_private = &done;
 337         rbio->bio.bi_end_io = bch2_read_single_folio_end_io;
 338
 339         __bchfs_readfolio(c, rbio, inode_inum(inode), folio);
 340         wait_for_completion(&done);
 341
 342         ret = blk_status_to_errno(rbio->bio.bi_status);
 343         bio_put(&rbio->bio);
 344
 345         if (ret < 0)
 346                 return ret;
 347
 348         folio_mark_uptodate(folio);
 349         return 0;
 350 }
 351
 352 int bch2_read_folio(struct file *file, struct folio *folio)
 353 {
 354         int ret;
 355
 356         ret = bch2_read_single_folio(folio, folio->mapping);
 357         folio_unlock(folio);
 358         return bch2_err_class(ret);
 359 }
 360
 361 /* writepages: */
 362
 363 struct bch_writepage_io {
 364         struct bch_inode_info           *inode;
 365
 366         /* must be last: */
 367         struct bch_write_op             op;
 368 };
 369
 370 struct bch_writepage_state {
 371         struct bch_writepage_io *io;
 372         struct bch_io_opts      opts;
 373         struct bch_folio_sector *tmp;
 374         unsigned                tmp_sectors;
 375 };
 376
 377 static inline struct bch_writepage_state bch_writepage_state_init(struct bch_fs *c,
 378                                                                   struct bch_inode_info *inode)
 379 {
 380         struct bch_writepage_state ret = { 0 };
 381
 382         bch2_inode_opts_get(&ret.opts, c, &inode->ei_inode);
 383         return ret;
 384 }
 385
 386 /*
 387  * Determine when a writepage io is full. We have to limit writepage bios to a
 388  * single page per bvec (i.e. 1MB with 4k pages) because that is the limit to
 389  * what the bounce path in bch2_write_extent() can handle. In theory we could
 390  * loosen this restriction for non-bounce I/O, but we don't have that context
 391  * here. Ideally, we can up this limit and make it configurable in the future
 392  * when the bounce path can be enhanced to accommodate larger source bios.
 393  */
 394 static inline bool bch_io_full(struct bch_writepage_io *io, unsigned len)
 395 {
 396         struct bio *bio = &io->op.wbio.bio;
 397         return bio_full(bio, len) ||
 398                 (bio->bi_iter.bi_size + len > BIO_MAX_VECS * PAGE_SIZE);
 399 }
 400
 401 static void bch2_writepage_io_done(struct bch_write_op *op)
 402 {
 403         struct bch_writepage_io *io =
 404                 container_of(op, struct bch_writepage_io, op);
 405         struct bch_fs *c = io->op.c;
 406         struct bio *bio = &io->op.wbio.bio;
 407         struct folio_iter fi;
 408         unsigned i;
 409
 410         if (io->op.error) {
 411                 set_bit(EI_INODE_ERROR, &io->inode->ei_flags);
 412
 413                 bio_for_each_folio_all(fi, bio) {
 414                         struct bch_folio *s;
 415
 416                         folio_set_error(fi.folio);
 417                         mapping_set_error(fi.folio->mapping, -EIO);
 418
 419                         s = __bch2_folio(fi.folio);
 420                         spin_lock(&s->lock);
 421                         for (i = 0; i < folio_sectors(fi.folio); i++)
 422                                 s->s[i].nr_replicas = 0;
 423                         spin_unlock(&s->lock);
 424                 }
 425         }
 426
 427         if (io->op.flags & BCH_WRITE_WROTE_DATA_INLINE) {
 428                 bio_for_each_folio_all(fi, bio) {
 429                         struct bch_folio *s;
 430
 431                         s = __bch2_folio(fi.folio);
 432                         spin_lock(&s->lock);
 433                         for (i = 0; i < folio_sectors(fi.folio); i++)
 434                                 s->s[i].nr_replicas = 0;
 435                         spin_unlock(&s->lock);
 436                 }
 437         }
 438
 439         /*
 440          * racing with fallocate can cause us to add fewer sectors than
 441          * expected - but we shouldn't add more sectors than expected:
 442          */
 443         WARN_ON_ONCE(io->op.i_sectors_delta > 0);
 444
 445         /*
 446          * (error (due to going RO) halfway through a page can screw that up
 447          * slightly)
 448          * XXX wtf?
 449            BUG_ON(io->op.op.i_sectors_delta >= PAGE_SECTORS);
 450          */
 451
 452         /*
 453          * PageWriteback is effectively our ref on the inode - fixup i_blocks
 454          * before calling end_page_writeback:
 455          */
 456         bch2_i_sectors_acct(c, io->inode, NULL, io->op.i_sectors_delta);
 457
 458         bio_for_each_folio_all(fi, bio) {
 459                 struct bch_folio *s = __bch2_folio(fi.folio);
 460
 461                 if (atomic_dec_and_test(&s->write_count))
 462                         folio_end_writeback(fi.folio);
 463         }
 464
 465         bio_put(&io->op.wbio.bio);
 466 }
 467
 468 static void bch2_writepage_do_io(struct bch_writepage_state *w)
 469 {
 470         struct bch_writepage_io *io = w->io;
 471
 472         w->io = NULL;
 473         closure_call(&io->op.cl, bch2_write, NULL, NULL);
 474 }
 475
 476 /*
 477  * Get a bch_writepage_io and add @page to it - appending to an existing one if
 478  * possible, else allocating a new one:
 479  */
 480 static void bch2_writepage_io_alloc(struct bch_fs *c,
 481                                     struct writeback_control *wbc,
 482                                     struct bch_writepage_state *w,
 483                                     struct bch_inode_info *inode,
 484                                     u64 sector,
 485                                     unsigned nr_replicas)
 486 {
 487         struct bch_write_op *op;
 488
 489         w->io = container_of(bio_alloc_bioset(NULL, BIO_MAX_VECS,
 490                                               REQ_OP_WRITE,
 491                                               GFP_KERNEL,
 492                                               &c->writepage_bioset),
 493                              struct bch_writepage_io, op.wbio.bio);
 494
 495         w->io->inode            = inode;
 496         op                      = &w->io->op;
 497         bch2_write_op_init(op, c, w->opts);
 498         op->target              = w->opts.foreground_target;
 499         op->nr_replicas         = nr_replicas;
 500         op->res.nr_replicas     = nr_replicas;
 501         op->write_point         = writepoint_hashed(inode->ei_last_dirtied);
 502         op->subvol              = inode->ei_subvol;
 503         op->pos                 = POS(inode->v.i_ino, sector);
 504         op->end_io              = bch2_writepage_io_done;
 505         op->devs_need_flush     = &inode->ei_devs_need_flush;
 506         op->wbio.bio.bi_iter.bi_sector = sector;
 507         op->wbio.bio.bi_opf     = wbc_to_write_flags(wbc);
 508 }
 509
 510 static int __bch2_writepage(struct folio *folio,
 511                             struct writeback_control *wbc,
 512                             void *data)
 513 {
 514         struct bch_inode_info *inode = to_bch_ei(folio->mapping->host);
 515         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 516         struct bch_writepage_state *w = data;
 517         struct bch_folio *s;
 518         unsigned i, offset, f_sectors, nr_replicas_this_write = U32_MAX;
 519         loff_t i_size = i_size_read(&inode->v);
 520         int ret;
 521
 522         EBUG_ON(!folio_test_uptodate(folio));
 523
 524         /* Is the folio fully inside i_size? */
 525         if (folio_end_pos(folio) <= i_size)
 526                 goto do_io;
 527
 528         /* Is the folio fully outside i_size? (truncate in progress) */
 529         if (folio_pos(folio) >= i_size) {
 530                 folio_unlock(folio);
 531                 return 0;
 532         }
 533
 534         /*
 535          * The folio straddles i_size.  It must be zeroed out on each and every
 536          * writepage invocation because it may be mmapped.  "A file is mapped
 537          * in multiples of the folio size.  For a file that is not a multiple of
 538          * the  folio size, the remaining memory is zeroed when mapped, and
 539          * writes to that region are not written out to the file."
 540          */
 541         folio_zero_segment(folio,
 542                            i_size - folio_pos(folio),
 543                            folio_size(folio));
 544 do_io:
 545         f_sectors = folio_sectors(folio);
 546         s = bch2_folio(folio);
 547
 548         if (f_sectors > w->tmp_sectors) {
 549                 kfree(w->tmp);
 550                 w->tmp = kcalloc(f_sectors, sizeof(struct bch_folio_sector), __GFP_NOFAIL);
 551                 w->tmp_sectors = f_sectors;
 552         }
 553
 554         /*
 555          * Things get really hairy with errors during writeback:
 556          */
 557         ret = bch2_get_folio_disk_reservation(c, inode, folio, false);
 558         BUG_ON(ret);
 559
 560         /* Before unlocking the page, get copy of reservations: */
 561         spin_lock(&s->lock);
 562         memcpy(w->tmp, s->s, sizeof(struct bch_folio_sector) * f_sectors);
 563
 564         for (i = 0; i < f_sectors; i++) {
 565                 if (s->s[i].state < SECTOR_dirty)
 566                         continue;
 567
 568                 nr_replicas_this_write =
 569                         min_t(unsigned, nr_replicas_this_write,
 570                               s->s[i].nr_replicas +
 571                               s->s[i].replicas_reserved);
 572         }
 573
 574         for (i = 0; i < f_sectors; i++) {
 575                 if (s->s[i].state < SECTOR_dirty)
 576                         continue;
 577
 578                 s->s[i].nr_replicas = w->opts.compression
 579                         ? 0 : nr_replicas_this_write;
 580
 581                 s->s[i].replicas_reserved = 0;
 582                 bch2_folio_sector_set(folio, s, i, SECTOR_allocated);
 583         }
 584         spin_unlock(&s->lock);
 585
 586         BUG_ON(atomic_read(&s->write_count));
 587         atomic_set(&s->write_count, 1);
 588
 589         BUG_ON(folio_test_writeback(folio));
 590         folio_start_writeback(folio);
 591
 592         folio_unlock(folio);
 593
 594         offset = 0;
 595         while (1) {
 596                 unsigned sectors = 0, dirty_sectors = 0, reserved_sectors = 0;
 597                 u64 sector;
 598
 599                 while (offset < f_sectors &&
 600                        w->tmp[offset].state < SECTOR_dirty)
 601                         offset++;
 602
 603                 if (offset == f_sectors)
 604                         break;
 605
 606                 while (offset + sectors < f_sectors &&
 607                        w->tmp[offset + sectors].state >= SECTOR_dirty) {
 608                         reserved_sectors += w->tmp[offset + sectors].replicas_reserved;
 609                         dirty_sectors += w->tmp[offset + sectors].state == SECTOR_dirty;
 610                         sectors++;
 611                 }
 612                 BUG_ON(!sectors);
 613
 614                 sector = folio_sector(folio) + offset;
 615
 616                 if (w->io &&
 617                     (w->io->op.res.nr_replicas != nr_replicas_this_write ||
 618                      bch_io_full(w->io, sectors << 9) ||
 619                      bio_end_sector(&w->io->op.wbio.bio) != sector))
 620                         bch2_writepage_do_io(w);
 621
 622                 if (!w->io)
 623                         bch2_writepage_io_alloc(c, wbc, w, inode, sector,
 624                                                 nr_replicas_this_write);
 625
 626                 atomic_inc(&s->write_count);
 627
 628                 BUG_ON(inode != w->io->inode);
 629                 BUG_ON(!bio_add_folio(&w->io->op.wbio.bio, folio,
 630                                      sectors << 9, offset << 9));
 631
 632                 /* Check for writing past i_size: */
 633                 WARN_ONCE((bio_end_sector(&w->io->op.wbio.bio) << 9) >
 634                           round_up(i_size, block_bytes(c)) &&
 635                           !test_bit(BCH_FS_emergency_ro, &c->flags),
 636                           "writing past i_size: %llu > %llu (unrounded %llu)\n",
 637                           bio_end_sector(&w->io->op.wbio.bio) << 9,
 638                           round_up(i_size, block_bytes(c)),
 639                           i_size);
 640
 641                 w->io->op.res.sectors += reserved_sectors;
 642                 w->io->op.i_sectors_delta -= dirty_sectors;
 643                 w->io->op.new_i_size = i_size;
 644
 645                 offset += sectors;
 646         }
 647
 648         if (atomic_dec_and_test(&s->write_count))
 649                 folio_end_writeback(folio);
 650
 651         return 0;
 652 }
 653
 654 int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 655 {
 656         struct bch_fs *c = mapping->host->i_sb->s_fs_info;
 657         struct bch_writepage_state w =
 658                 bch_writepage_state_init(c, to_bch_ei(mapping->host));
 659         struct blk_plug plug;
 660         int ret;
 661
 662         blk_start_plug(&plug);
 663         ret = write_cache_pages(mapping, wbc, __bch2_writepage, &w);
 664         if (w.io)
 665                 bch2_writepage_do_io(&w);
 666         blk_finish_plug(&plug);
 667         kfree(w.tmp);
 668         return bch2_err_class(ret);
 669 }
 670
 671 /* buffered writes: */
 672
 673 int bch2_write_begin(struct file *file, struct address_space *mapping,
 674                      loff_t pos, unsigned len,
 675                      struct page **pagep, void **fsdata)
 676 {
 677         struct bch_inode_info *inode = to_bch_ei(mapping->host);
 678         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 679         struct bch2_folio_reservation *res;
 680         struct folio *folio;
 681         unsigned offset;
 682         int ret = -ENOMEM;
 683
 684         res = kmalloc(sizeof(*res), GFP_KERNEL);
 685         if (!res)
 686                 return -ENOMEM;
 687
 688         bch2_folio_reservation_init(c, inode, res);
 689         *fsdata = res;
 690
 691         bch2_pagecache_add_get(inode);
 692
 693         folio = __filemap_get_folio(mapping, pos >> PAGE_SHIFT,
 694                                 FGP_LOCK|FGP_WRITE|FGP_CREAT|FGP_STABLE,
 695                                 mapping_gfp_mask(mapping));
 696         if (IS_ERR_OR_NULL(folio))
 697                 goto err_unlock;
 698
 699         offset = pos - folio_pos(folio);
 700         len = min_t(size_t, len, folio_end_pos(folio) - pos);
 701
 702         if (folio_test_uptodate(folio))
 703                 goto out;
 704
 705         /* If we're writing entire folio, don't need to read it in first: */
 706         if (!offset && len == folio_size(folio))
 707                 goto out;
 708
 709         if (!offset && pos + len >= inode->v.i_size) {
 710                 folio_zero_segment(folio, len, folio_size(folio));
 711                 flush_dcache_folio(folio);
 712                 goto out;
 713         }
 714
 715         if (folio_pos(folio) >= inode->v.i_size) {
 716                 folio_zero_segments(folio, 0, offset, offset + len, folio_size(folio));
 717                 flush_dcache_folio(folio);
 718                 goto out;
 719         }
 720 readpage:
 721         ret = bch2_read_single_folio(folio, mapping);
 722         if (ret)
 723                 goto err;
 724 out:
 725         ret = bch2_folio_set(c, inode_inum(inode), &folio, 1);
 726         if (ret)
 727                 goto err;
 728
 729         ret = bch2_folio_reservation_get(c, inode, folio, res, offset, len);
 730         if (ret) {
 731                 if (!folio_test_uptodate(folio)) {
 732                         /*
 733                          * If the folio hasn't been read in, we won't know if we
 734                          * actually need a reservation - we don't actually need
 735                          * to read here, we just need to check if the folio is
 736                          * fully backed by uncompressed data:
 737                          */
 738                         goto readpage;
 739                 }
 740
 741                 goto err;
 742         }
 743
 744         *pagep = &folio->page;
 745         return 0;
 746 err:
 747         folio_unlock(folio);
 748         folio_put(folio);
 749         *pagep = NULL;
 750 err_unlock:
 751         bch2_pagecache_add_put(inode);
 752         kfree(res);
 753         *fsdata = NULL;
 754         return bch2_err_class(ret);
 755 }
 756
 757 int bch2_write_end(struct file *file, struct address_space *mapping,
 758                    loff_t pos, unsigned len, unsigned copied,
 759                    struct page *page, void *fsdata)
 760 {
 761         struct bch_inode_info *inode = to_bch_ei(mapping->host);
 762         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 763         struct bch2_folio_reservation *res = fsdata;
 764         struct folio *folio = page_folio(page);
 765         unsigned offset = pos - folio_pos(folio);
 766
 767         lockdep_assert_held(&inode->v.i_rwsem);
 768         BUG_ON(offset + copied > folio_size(folio));
 769
 770         if (unlikely(copied < len && !folio_test_uptodate(folio))) {
 771                 /*
 772                  * The folio needs to be read in, but that would destroy
 773                  * our partial write - simplest thing is to just force
 774                  * userspace to redo the write:
 775                  */
 776                 folio_zero_range(folio, 0, folio_size(folio));
 777                 flush_dcache_folio(folio);
 778                 copied = 0;
 779         }
 780
 781         spin_lock(&inode->v.i_lock);
 782         if (pos + copied > inode->v.i_size)
 783                 i_size_write(&inode->v, pos + copied);
 784         spin_unlock(&inode->v.i_lock);
 785
 786         if (copied) {
 787                 if (!folio_test_uptodate(folio))
 788                         folio_mark_uptodate(folio);
 789
 790                 bch2_set_folio_dirty(c, inode, folio, res, offset, copied);
 791
 792                 inode->ei_last_dirtied = (unsigned long) current;
 793         }
 794
 795         folio_unlock(folio);
 796         folio_put(folio);
 797         bch2_pagecache_add_put(inode);
 798
 799         bch2_folio_reservation_put(c, inode, res);
 800         kfree(res);
 801
 802         return copied;
 803 }
 804
 805 static noinline void folios_trunc(folios *fs, struct folio **fi)
 806 {
 807         while (fs->data + fs->nr > fi) {
 808                 struct folio *f = darray_pop(fs);
 809
 810                 folio_unlock(f);
 811                 folio_put(f);
 812         }
 813 }
 814
 815 static int __bch2_buffered_write(struct bch_inode_info *inode,
 816                                  struct address_space *mapping,
 817                                  struct iov_iter *iter,
 818                                  loff_t pos, unsigned len)
 819 {
 820         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 821         struct bch2_folio_reservation res;
 822         folios fs;
 823         struct folio *f;
 824         unsigned copied = 0, f_offset, f_copied;
 825         u64 end = pos + len, f_pos, f_len;
 826         loff_t last_folio_pos = inode->v.i_size;
 827         int ret = 0;
 828
 829         BUG_ON(!len);
 830
 831         bch2_folio_reservation_init(c, inode, &res);
 832         darray_init(&fs);
 833
 834         ret = bch2_filemap_get_contig_folios_d(mapping, pos, end,
 835                                    FGP_LOCK|FGP_WRITE|FGP_STABLE|FGP_CREAT,
 836                                    mapping_gfp_mask(mapping),
 837                                    &fs);
 838         if (ret)
 839                 goto out;
 840
 841         BUG_ON(!fs.nr);
 842
 843         f = darray_first(fs);
 844         if (pos != folio_pos(f) && !folio_test_uptodate(f)) {
 845                 ret = bch2_read_single_folio(f, mapping);
 846                 if (ret)
 847                         goto out;
 848         }
 849
 850         f = darray_last(fs);
 851         end = min(end, folio_end_pos(f));
 852         last_folio_pos = folio_pos(f);
 853         if (end != folio_end_pos(f) && !folio_test_uptodate(f)) {
 854                 if (end >= inode->v.i_size) {
 855                         folio_zero_range(f, 0, folio_size(f));
 856                 } else {
 857                         ret = bch2_read_single_folio(f, mapping);
 858                         if (ret)
 859                                 goto out;
 860                 }
 861         }
 862
 863         ret = bch2_folio_set(c, inode_inum(inode), fs.data, fs.nr);
 864         if (ret)
 865                 goto out;
 866
 867         f_pos = pos;
 868         f_offset = pos - folio_pos(darray_first(fs));
 869         darray_for_each(fs, fi) {
 870                 f = *fi;
 871                 f_len = min(end, folio_end_pos(f)) - f_pos;
 872
 873                 /*
 874                  * XXX: per POSIX and fstests generic/275, on -ENOSPC we're
 875                  * supposed to write as much as we have disk space for.
 876                  *
 877                  * On failure here we should still write out a partial page if
 878                  * we aren't completely out of disk space - we don't do that
 879                  * yet:
 880                  */
 881                 ret = bch2_folio_reservation_get(c, inode, f, &res, f_offset, f_len);
 882                 if (unlikely(ret)) {
 883                         folios_trunc(&fs, fi);
 884                         if (!fs.nr)
 885                                 goto out;
 886
 887                         end = min(end, folio_end_pos(darray_last(fs)));
 888                         break;
 889                 }
 890
 891                 f_pos = folio_end_pos(f);
 892                 f_offset = 0;
 893         }
 894
 895         if (mapping_writably_mapped(mapping))
 896                 darray_for_each(fs, fi)
 897                         flush_dcache_folio(*fi);
 898
 899         f_pos = pos;
 900         f_offset = pos - folio_pos(darray_first(fs));
 901         darray_for_each(fs, fi) {
 902                 f = *fi;
 903                 f_len = min(end, folio_end_pos(f)) - f_pos;
 904                 f_copied = copy_page_from_iter_atomic(&f->page, f_offset, f_len, iter);
 905                 if (!f_copied) {
 906                         folios_trunc(&fs, fi);
 907                         break;
 908                 }
 909
 910                 if (!folio_test_uptodate(f) &&
 911                     f_copied != folio_size(f) &&
 912                     pos + copied + f_copied < inode->v.i_size) {
 913                         iov_iter_revert(iter, f_copied);
 914                         folio_zero_range(f, 0, folio_size(f));
 915                         folios_trunc(&fs, fi);
 916                         break;
 917                 }
 918
 919                 flush_dcache_folio(f);
 920                 copied += f_copied;
 921
 922                 if (f_copied != f_len) {
 923                         folios_trunc(&fs, fi + 1);
 924                         break;
 925                 }
 926
 927                 f_pos = folio_end_pos(f);
 928                 f_offset = 0;
 929         }
 930
 931         if (!copied)
 932                 goto out;
 933
 934         end = pos + copied;
 935
 936         spin_lock(&inode->v.i_lock);
 937         if (end > inode->v.i_size)
 938                 i_size_write(&inode->v, end);
 939         spin_unlock(&inode->v.i_lock);
 940
 941         f_pos = pos;
 942         f_offset = pos - folio_pos(darray_first(fs));
 943         darray_for_each(fs, fi) {
 944                 f = *fi;
 945                 f_len = min(end, folio_end_pos(f)) - f_pos;
 946
 947                 if (!folio_test_uptodate(f))
 948                         folio_mark_uptodate(f);
 949
 950                 bch2_set_folio_dirty(c, inode, f, &res, f_offset, f_len);
 951
 952                 f_pos = folio_end_pos(f);
 953                 f_offset = 0;
 954         }
 955
 956         inode->ei_last_dirtied = (unsigned long) current;
 957 out:
 958         darray_for_each(fs, fi) {
 959                 folio_unlock(*fi);
 960                 folio_put(*fi);
 961         }
 962
 963         /*
 964          * If the last folio added to the mapping starts beyond current EOF, we
 965          * performed a short write but left around at least one post-EOF folio.
 966          * Clean up the mapping before we return.
 967          */
 968         if (last_folio_pos >= inode->v.i_size)
 969                 truncate_pagecache(&inode->v, inode->v.i_size);
 970
 971         darray_exit(&fs);
 972         bch2_folio_reservation_put(c, inode, &res);
 973
 974         return copied ?: ret;
 975 }
 976
 977 static ssize_t bch2_buffered_write(struct kiocb *iocb, struct iov_iter *iter)
 978 {
 979         struct file *file = iocb->ki_filp;
 980         struct address_space *mapping = file->f_mapping;
 981         struct bch_inode_info *inode = file_bch_inode(file);
 982         loff_t pos = iocb->ki_pos;
 983         ssize_t written = 0;
 984         int ret = 0;
 985
 986         bch2_pagecache_add_get(inode);
 987
 988         do {
 989                 unsigned offset = pos & (PAGE_SIZE - 1);
 990                 unsigned bytes = iov_iter_count(iter);
 991 again:
 992                 /*
 993                  * Bring in the user page that we will copy from _first_.
 994                  * Otherwise there's a nasty deadlock on copying from the
 995                  * same page as we're writing to, without it being marked
 996                  * up-to-date.
 997                  *
 998                  * Not only is this an optimisation, but it is also required
 999                  * to check that the address is actually valid, when atomic
1000                  * usercopies are used, below.
1001                  */
1002                 if (unlikely(fault_in_iov_iter_readable(iter, bytes))) {
1003                         bytes = min_t(unsigned long, iov_iter_count(iter),
1004                                       PAGE_SIZE - offset);
1005
1006                         if (unlikely(fault_in_iov_iter_readable(iter, bytes))) {
1007                                 ret = -EFAULT;
1008                                 break;
1009                         }
1010                 }
1011
1012                 if (unlikely(fatal_signal_pending(current))) {
1013                         ret = -EINTR;
1014                         break;
1015                 }
1016
1017                 ret = __bch2_buffered_write(inode, mapping, iter, pos, bytes);
1018                 if (unlikely(ret < 0))
1019                         break;
1020
1021                 cond_resched();
1022
1023                 if (unlikely(ret == 0)) {
1024                         /*
1025                          * If we were unable to copy any data at all, we must
1026                          * fall back to a single segment length write.
1027                          *
1028                          * If we didn't fallback here, we could livelock
1029                          * because not all segments in the iov can be copied at
1030                          * once without a pagefault.
1031                          */
1032                         bytes = min_t(unsigned long, PAGE_SIZE - offset,
1033                                       iov_iter_single_seg_count(iter));
1034                         goto again;
1035                 }
1036                 pos += ret;
1037                 written += ret;
1038                 ret = 0;
1039
1040                 balance_dirty_pages_ratelimited(mapping);
1041         } while (iov_iter_count(iter));
1042
1043         bch2_pagecache_add_put(inode);
1044
1045         return written ? written : ret;
1046 }
1047
1048 ssize_t bch2_write_iter(struct kiocb *iocb, struct iov_iter *from)
1049 {
1050         struct file *file = iocb->ki_filp;
1051         struct bch_inode_info *inode = file_bch_inode(file);
1052         ssize_t ret;
1053
1054         if (iocb->ki_flags & IOCB_DIRECT) {
1055                 ret = bch2_direct_write(iocb, from);
1056                 goto out;
1057         }
1058
1059         inode_lock(&inode->v);
1060
1061         ret = generic_write_checks(iocb, from);
1062         if (ret <= 0)
1063                 goto unlock;
1064
1065         ret = file_remove_privs(file);
1066         if (ret)
1067                 goto unlock;
1068
1069         ret = file_update_time(file);
1070         if (ret)
1071                 goto unlock;
1072
1073         ret = bch2_buffered_write(iocb, from);
1074         if (likely(ret > 0))
1075                 iocb->ki_pos += ret;
1076 unlock:
1077         inode_unlock(&inode->v);
1078
1079         if (ret > 0)
1080                 ret = generic_write_sync(iocb, ret);
1081 out:
1082         return bch2_err_class(ret);
1083 }
1084
1085 void bch2_fs_fs_io_buffered_exit(struct bch_fs *c)
1086 {
1087         bioset_exit(&c->writepage_bioset);
1088 }
1089
1090 int bch2_fs_fs_io_buffered_init(struct bch_fs *c)
1091 {
1092         if (bioset_init(&c->writepage_bioset,
1093                         4, offsetof(struct bch_writepage_io, op.wbio.bio),
1094                         BIOSET_NEED_BVECS))
1095                 return -BCH_ERR_ENOMEM_writepage_bioset_init;
1096
1097         return 0;
1098 }
1099
1100 #endif /* NO_BCACHEFS_FS */