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