fs/ext4/page-io.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/ext4/page-io.c
   4  *
   5  * This contains the new page_io functions for ext4
   6  *
   7  * Written by Theodore Ts'o, 2010.
   8  */
   9
  10 #include <linux/fs.h>
  11 #include <linux/time.h>
  12 #include <linux/highuid.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/quotaops.h>
  15 #include <linux/string.h>
  16 #include <linux/buffer_head.h>
  17 #include <linux/writeback.h>
  18 #include <linux/pagevec.h>
  19 #include <linux/mpage.h>
  20 #include <linux/namei.h>
  21 #include <linux/uio.h>
  22 #include <linux/bio.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/kernel.h>
  25 #include <linux/slab.h>
  26 #include <linux/mm.h>
  27 #include <linux/sched/mm.h>
  28
  29 #include "ext4_jbd2.h"
  30 #include "xattr.h"
  31 #include "acl.h"
  32
  33 static struct kmem_cache *io_end_cachep;
  34 static struct kmem_cache *io_end_vec_cachep;
  35
  36 int __init ext4_init_pageio(void)
  37 {
  38         io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
  39         if (io_end_cachep == NULL)
  40                 return -ENOMEM;
  41
  42         io_end_vec_cachep = KMEM_CACHE(ext4_io_end_vec, 0);
  43         if (io_end_vec_cachep == NULL) {
  44                 kmem_cache_destroy(io_end_cachep);
  45                 return -ENOMEM;
  46         }
  47         return 0;
  48 }
  49
  50 void ext4_exit_pageio(void)
  51 {
  52         kmem_cache_destroy(io_end_cachep);
  53         kmem_cache_destroy(io_end_vec_cachep);
  54 }
  55
  56 struct ext4_io_end_vec *ext4_alloc_io_end_vec(ext4_io_end_t *io_end)
  57 {
  58         struct ext4_io_end_vec *io_end_vec;
  59
  60         io_end_vec = kmem_cache_zalloc(io_end_vec_cachep, GFP_NOFS);
  61         if (!io_end_vec)
  62                 return ERR_PTR(-ENOMEM);
  63         INIT_LIST_HEAD(&io_end_vec->list);
  64         list_add_tail(&io_end_vec->list, &io_end->list_vec);
  65         return io_end_vec;
  66 }
  67
  68 static void ext4_free_io_end_vec(ext4_io_end_t *io_end)
  69 {
  70         struct ext4_io_end_vec *io_end_vec, *tmp;
  71
  72         if (list_empty(&io_end->list_vec))
  73                 return;
  74         list_for_each_entry_safe(io_end_vec, tmp, &io_end->list_vec, list) {
  75                 list_del(&io_end_vec->list);
  76                 kmem_cache_free(io_end_vec_cachep, io_end_vec);
  77         }
  78 }
  79
  80 struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end)
  81 {
  82         BUG_ON(list_empty(&io_end->list_vec));
  83         return list_last_entry(&io_end->list_vec, struct ext4_io_end_vec, list);
  84 }
  85
  86 /*
  87  * Print an buffer I/O error compatible with the fs/buffer.c.  This
  88  * provides compatibility with dmesg scrapers that look for a specific
  89  * buffer I/O error message.  We really need a unified error reporting
  90  * structure to userspace ala Digital Unix's uerf system, but it's
  91  * probably not going to happen in my lifetime, due to LKML politics...
  92  */
  93 static void buffer_io_error(struct buffer_head *bh)
  94 {
  95         printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n",
  96                        bh->b_bdev,
  97                         (unsigned long long)bh->b_blocknr);
  98 }
  99
 100 static void ext4_finish_bio(struct bio *bio)
 101 {
 102         struct folio_iter fi;
 103
 104         bio_for_each_folio_all(fi, bio) {
 105                 struct folio *folio = fi.folio;
 106                 struct folio *io_folio = NULL;
 107                 struct buffer_head *bh, *head;
 108                 size_t bio_start = fi.offset;
 109                 size_t bio_end = bio_start + fi.length;
 110                 unsigned under_io = 0;
 111                 unsigned long flags;
 112
 113                 if (fscrypt_is_bounce_folio(folio)) {
 114                         io_folio = folio;
 115                         folio = fscrypt_pagecache_folio(folio);
 116                 }
 117
 118                 if (bio->bi_status) {
 119                         int err = blk_status_to_errno(bio->bi_status);
 120                         mapping_set_error(folio->mapping, err);
 121                 }
 122                 bh = head = folio_buffers(folio);
 123                 /*
 124                  * We check all buffers in the folio under b_uptodate_lock
 125                  * to avoid races with other end io clearing async_write flags
 126                  */
 127                 spin_lock_irqsave(&head->b_uptodate_lock, flags);
 128                 do {
 129                         if (bh_offset(bh) < bio_start ||
 130                             bh_offset(bh) + bh->b_size > bio_end) {
 131                                 if (buffer_async_write(bh))
 132                                         under_io++;
 133                                 continue;
 134                         }
 135                         clear_buffer_async_write(bh);
 136                         if (bio->bi_status) {
 137                                 set_buffer_write_io_error(bh);
 138                                 buffer_io_error(bh);
 139                         }
 140                 } while ((bh = bh->b_this_page) != head);
 141                 spin_unlock_irqrestore(&head->b_uptodate_lock, flags);
 142                 if (!under_io) {
 143                         fscrypt_free_bounce_page(&io_folio->page);
 144                         folio_end_writeback(folio);
 145                 }
 146         }
 147 }
 148
 149 static void ext4_release_io_end(ext4_io_end_t *io_end)
 150 {
 151         struct bio *bio, *next_bio;
 152
 153         BUG_ON(!list_empty(&io_end->list));
 154         BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
 155         WARN_ON(io_end->handle);
 156
 157         for (bio = io_end->bio; bio; bio = next_bio) {
 158                 next_bio = bio->bi_private;
 159                 ext4_finish_bio(bio);
 160                 bio_put(bio);
 161         }
 162         ext4_free_io_end_vec(io_end);
 163         kmem_cache_free(io_end_cachep, io_end);
 164 }
 165
 166 /*
 167  * On successful IO, check a range of space and convert unwritten extents to
 168  * written. On IO failure, check if journal abort is needed. Note that
 169  * we are protected from truncate touching same part of extent tree by the
 170  * fact that truncate code waits for all DIO to finish (thus exclusion from
 171  * direct IO is achieved) and also waits for PageWriteback bits. Thus we
 172  * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
 173  * completed (happens from ext4_free_ioend()).
 174  */
 175 static int ext4_end_io_end(ext4_io_end_t *io_end)
 176 {
 177         struct inode *inode = io_end->inode;
 178         handle_t *handle = io_end->handle;
 179         struct super_block *sb = inode->i_sb;
 180         int ret = 0;
 181
 182         ext4_debug("ext4_end_io_nolock: io_end 0x%p from inode %lu,list->next 0x%p,"
 183                    "list->prev 0x%p\n",
 184                    io_end, inode->i_ino, io_end->list.next, io_end->list.prev);
 185
 186         /*
 187          * Do not convert the unwritten extents if data writeback fails,
 188          * or stale data may be exposed.
 189          */
 190         io_end->handle = NULL;  /* Following call will use up the handle */
 191         if (unlikely(io_end->flag & EXT4_IO_END_FAILED)) {
 192                 ret = -EIO;
 193                 if (handle)
 194                         jbd2_journal_free_reserved(handle);
 195
 196                 if (test_opt(sb, DATA_ERR_ABORT))
 197                         jbd2_journal_abort(EXT4_SB(sb)->s_journal, ret);
 198         } else {
 199                 ret = ext4_convert_unwritten_io_end_vec(handle, io_end);
 200         }
 201         if (ret < 0 && !ext4_emergency_state(sb) &&
 202             io_end->flag & EXT4_IO_END_UNWRITTEN) {
 203                 ext4_msg(sb, KERN_EMERG,
 204                          "failed to convert unwritten extents to written "
 205                          "extents -- potential data loss!  "
 206                          "(inode %lu, error %d)", inode->i_ino, ret);
 207         }
 208
 209         ext4_clear_io_unwritten_flag(io_end);
 210         ext4_release_io_end(io_end);
 211         return ret;
 212 }
 213
 214 static void dump_completed_IO(struct inode *inode, struct list_head *head)
 215 {
 216 #ifdef  EXT4FS_DEBUG
 217         struct list_head *cur, *before, *after;
 218         ext4_io_end_t *io_end, *io_end0, *io_end1;
 219
 220         if (list_empty(head))
 221                 return;
 222
 223         ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
 224         list_for_each_entry(io_end, head, list) {
 225                 cur = &io_end->list;
 226                 before = cur->prev;
 227                 io_end0 = container_of(before, ext4_io_end_t, list);
 228                 after = cur->next;
 229                 io_end1 = container_of(after, ext4_io_end_t, list);
 230
 231                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 232                             io_end, inode->i_ino, io_end0, io_end1);
 233         }
 234 #endif
 235 }
 236
 237 static bool ext4_io_end_defer_completion(ext4_io_end_t *io_end)
 238 {
 239         if (io_end->flag & EXT4_IO_END_UNWRITTEN)
 240                 return true;
 241         if (test_opt(io_end->inode->i_sb, DATA_ERR_ABORT) &&
 242             io_end->flag & EXT4_IO_END_FAILED)
 243                 return true;
 244         return false;
 245 }
 246
 247 /* Add the io_end to per-inode completed end_io list. */
 248 static void ext4_add_complete_io(ext4_io_end_t *io_end)
 249 {
 250         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 251         struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
 252         struct workqueue_struct *wq;
 253         unsigned long flags;
 254
 255         /* Only reserved conversions or pending IO errors will enter here. */
 256         WARN_ON(!(io_end->flag & EXT4_IO_END_DEFER_COMPLETION));
 257         WARN_ON(io_end->flag & EXT4_IO_END_UNWRITTEN &&
 258                 !io_end->handle && sbi->s_journal);
 259
 260         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 261         wq = sbi->rsv_conversion_wq;
 262         if (list_empty(&ei->i_rsv_conversion_list))
 263                 queue_work(wq, &ei->i_rsv_conversion_work);
 264         list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
 265         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 266 }
 267
 268 static int ext4_do_flush_completed_IO(struct inode *inode,
 269                                       struct list_head *head)
 270 {
 271         ext4_io_end_t *io_end;
 272         struct list_head unwritten;
 273         unsigned long flags;
 274         struct ext4_inode_info *ei = EXT4_I(inode);
 275         int err, ret = 0;
 276
 277         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 278         dump_completed_IO(inode, head);
 279         list_replace_init(head, &unwritten);
 280         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 281
 282         while (!list_empty(&unwritten)) {
 283                 io_end = list_entry(unwritten.next, ext4_io_end_t, list);
 284                 BUG_ON(!(io_end->flag & EXT4_IO_END_DEFER_COMPLETION));
 285                 list_del_init(&io_end->list);
 286
 287                 err = ext4_end_io_end(io_end);
 288                 if (unlikely(!ret && err))
 289                         ret = err;
 290         }
 291         return ret;
 292 }
 293
 294 /*
 295  * Used to convert unwritten extents to written extents upon IO completion,
 296  * or used to abort the journal upon IO errors.
 297  */
 298 void ext4_end_io_rsv_work(struct work_struct *work)
 299 {
 300         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 301                                                   i_rsv_conversion_work);
 302         ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
 303 }
 304
 305 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 306 {
 307         ext4_io_end_t *io_end = kmem_cache_zalloc(io_end_cachep, flags);
 308
 309         if (io_end) {
 310                 io_end->inode = inode;
 311                 INIT_LIST_HEAD(&io_end->list);
 312                 INIT_LIST_HEAD(&io_end->list_vec);
 313                 refcount_set(&io_end->count, 1);
 314         }
 315         return io_end;
 316 }
 317
 318 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
 319 {
 320         if (refcount_dec_and_test(&io_end->count)) {
 321                 if (io_end->flag & EXT4_IO_END_FAILED ||
 322                     (io_end->flag & EXT4_IO_END_UNWRITTEN &&
 323                      !list_empty(&io_end->list_vec))) {
 324                         ext4_add_complete_io(io_end);
 325                         return;
 326                 }
 327                 ext4_release_io_end(io_end);
 328         }
 329 }
 330
 331 int ext4_put_io_end(ext4_io_end_t *io_end)
 332 {
 333         if (refcount_dec_and_test(&io_end->count)) {
 334                 if (ext4_io_end_defer_completion(io_end))
 335                         return ext4_end_io_end(io_end);
 336
 337                 ext4_release_io_end(io_end);
 338         }
 339         return 0;
 340 }
 341
 342 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
 343 {
 344         refcount_inc(&io_end->count);
 345         return io_end;
 346 }
 347
 348 /* BIO completion function for page writeback */
 349 static void ext4_end_bio(struct bio *bio)
 350 {
 351         ext4_io_end_t *io_end = bio->bi_private;
 352         sector_t bi_sector = bio->bi_iter.bi_sector;
 353
 354         if (WARN_ONCE(!io_end, "io_end is NULL: %pg: sector %Lu len %u err %d\n",
 355                       bio->bi_bdev,
 356                       (long long) bio->bi_iter.bi_sector,
 357                       (unsigned) bio_sectors(bio),
 358                       bio->bi_status)) {
 359                 ext4_finish_bio(bio);
 360                 bio_put(bio);
 361                 return;
 362         }
 363         bio->bi_end_io = NULL;
 364
 365         if (bio->bi_status) {
 366                 struct inode *inode = io_end->inode;
 367
 368                 ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
 369                              "starting block %llu)",
 370                              bio->bi_status, inode->i_ino,
 371                              (unsigned long long)
 372                              bi_sector >> (inode->i_blkbits - 9));
 373                 io_end->flag |= EXT4_IO_END_FAILED;
 374                 mapping_set_error(inode->i_mapping,
 375                                 blk_status_to_errno(bio->bi_status));
 376         }
 377
 378         if (ext4_io_end_defer_completion(io_end)) {
 379                 /*
 380                  * Link bio into list hanging from io_end. We have to do it
 381                  * atomically as bio completions can be racing against each
 382                  * other.
 383                  */
 384                 bio->bi_private = xchg(&io_end->bio, bio);
 385                 ext4_put_io_end_defer(io_end);
 386         } else {
 387                 /*
 388                  * Drop io_end reference early. Inode can get freed once
 389                  * we finish the bio.
 390                  */
 391                 ext4_put_io_end_defer(io_end);
 392                 ext4_finish_bio(bio);
 393                 bio_put(bio);
 394         }
 395 }
 396
 397 void ext4_io_submit(struct ext4_io_submit *io)
 398 {
 399         struct bio *bio = io->io_bio;
 400
 401         if (bio) {
 402                 if (io->io_wbc->sync_mode == WB_SYNC_ALL)
 403                         io->io_bio->bi_opf |= REQ_SYNC;
 404                 submit_bio(io->io_bio);
 405         }
 406         io->io_bio = NULL;
 407 }
 408
 409 void ext4_io_submit_init(struct ext4_io_submit *io,
 410                          struct writeback_control *wbc)
 411 {
 412         io->io_wbc = wbc;
 413         io->io_bio = NULL;
 414         io->io_end = NULL;
 415 }
 416
 417 static void io_submit_init_bio(struct ext4_io_submit *io,
 418                                struct buffer_head *bh)
 419 {
 420         struct bio *bio;
 421
 422         /*
 423          * bio_alloc will _always_ be able to allocate a bio if
 424          * __GFP_DIRECT_RECLAIM is set, see comments for bio_alloc_bioset().
 425          */
 426         bio = bio_alloc(bh->b_bdev, BIO_MAX_VECS, REQ_OP_WRITE, GFP_NOIO);
 427         fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
 428         bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 429         bio->bi_end_io = ext4_end_bio;
 430         bio->bi_private = ext4_get_io_end(io->io_end);
 431         io->io_bio = bio;
 432         io->io_next_block = bh->b_blocknr;
 433         wbc_init_bio(io->io_wbc, bio);
 434 }
 435
 436 static void io_submit_add_bh(struct ext4_io_submit *io,
 437                              struct inode *inode,
 438                              struct folio *folio,
 439                              struct folio *io_folio,
 440                              struct buffer_head *bh)
 441 {
 442         if (io->io_bio && (bh->b_blocknr != io->io_next_block ||
 443                            !fscrypt_mergeable_bio_bh(io->io_bio, bh))) {
 444 submit_and_retry:
 445                 ext4_io_submit(io);
 446         }
 447         if (io->io_bio == NULL) {
 448                 io_submit_init_bio(io, bh);
 449                 io->io_bio->bi_write_hint = inode->i_write_hint;
 450         }
 451         if (!bio_add_folio(io->io_bio, io_folio, bh->b_size, bh_offset(bh)))
 452                 goto submit_and_retry;
 453         wbc_account_cgroup_owner(io->io_wbc, folio, bh->b_size);
 454         io->io_next_block++;
 455 }
 456
 457 int ext4_bio_write_folio(struct ext4_io_submit *io, struct folio *folio,
 458                 size_t len)
 459 {
 460         struct folio *io_folio = folio;
 461         struct inode *inode = folio->mapping->host;
 462         unsigned block_start;
 463         struct buffer_head *bh, *head;
 464         int ret = 0;
 465         int nr_to_submit = 0;
 466         struct writeback_control *wbc = io->io_wbc;
 467         bool keep_towrite = false;
 468
 469         BUG_ON(!folio_test_locked(folio));
 470         BUG_ON(folio_test_writeback(folio));
 471
 472         /*
 473          * Comments copied from block_write_full_folio:
 474          *
 475          * The folio straddles i_size.  It must be zeroed out on each and every
 476          * writepage invocation because it may be mmapped.  "A file is mapped
 477          * in multiples of the page size.  For a file that is not a multiple of
 478          * the page size, the remaining memory is zeroed when mapped, and
 479          * writes to that region are not written out to the file."
 480          */
 481         if (len < folio_size(folio))
 482                 folio_zero_segment(folio, len, folio_size(folio));
 483         /*
 484          * In the first loop we prepare and mark buffers to submit. We have to
 485          * mark all buffers in the folio before submitting so that
 486          * folio_end_writeback() cannot be called from ext4_end_bio() when IO
 487          * on the first buffer finishes and we are still working on submitting
 488          * the second buffer.
 489          */
 490         bh = head = folio_buffers(folio);
 491         do {
 492                 block_start = bh_offset(bh);
 493                 if (block_start >= len) {
 494                         clear_buffer_dirty(bh);
 495                         set_buffer_uptodate(bh);
 496                         continue;
 497                 }
 498                 if (!buffer_dirty(bh) || buffer_delay(bh) ||
 499                     !buffer_mapped(bh) || buffer_unwritten(bh)) {
 500                         /* A hole? We can safely clear the dirty bit */
 501                         if (!buffer_mapped(bh))
 502                                 clear_buffer_dirty(bh);
 503                         /*
 504                          * Keeping dirty some buffer we cannot write? Make sure
 505                          * to redirty the folio and keep TOWRITE tag so that
 506                          * racing WB_SYNC_ALL writeback does not skip the folio.
 507                          * This happens e.g. when doing writeout for
 508                          * transaction commit or when journalled data is not
 509                          * yet committed.
 510                          */
 511                         if (buffer_dirty(bh) ||
 512                             (buffer_jbd(bh) && buffer_jbddirty(bh))) {
 513                                 if (!folio_test_dirty(folio))
 514                                         folio_redirty_for_writepage(wbc, folio);
 515                                 keep_towrite = true;
 516                         }
 517                         continue;
 518                 }
 519                 if (buffer_new(bh))
 520                         clear_buffer_new(bh);
 521                 set_buffer_async_write(bh);
 522                 clear_buffer_dirty(bh);
 523                 nr_to_submit++;
 524         } while ((bh = bh->b_this_page) != head);
 525
 526         /* Nothing to submit? Just unlock the folio... */
 527         if (!nr_to_submit)
 528                 return 0;
 529
 530         bh = head = folio_buffers(folio);
 531
 532         /*
 533          * If any blocks are being written to an encrypted file, encrypt them
 534          * into a bounce page.  For simplicity, just encrypt until the last
 535          * block which might be needed.  This may cause some unneeded blocks
 536          * (e.g. holes) to be unnecessarily encrypted, but this is rare and
 537          * can't happen in the common case of blocksize == PAGE_SIZE.
 538          */
 539         if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
 540                 gfp_t gfp_flags = GFP_NOFS;
 541                 unsigned int enc_bytes = round_up(len, i_blocksize(inode));
 542                 struct page *bounce_page;
 543
 544                 /*
 545                  * Since bounce page allocation uses a mempool, we can only use
 546                  * a waiting mask (i.e. request guaranteed allocation) on the
 547                  * first page of the bio.  Otherwise it can deadlock.
 548                  */
 549                 if (io->io_bio)
 550                         gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
 551         retry_encrypt:
 552                 bounce_page = fscrypt_encrypt_pagecache_blocks(folio,
 553                                         enc_bytes, 0, gfp_flags);
 554                 if (IS_ERR(bounce_page)) {
 555                         ret = PTR_ERR(bounce_page);
 556                         if (ret == -ENOMEM &&
 557                             (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
 558                                 gfp_t new_gfp_flags = GFP_NOFS;
 559                                 if (io->io_bio)
 560                                         ext4_io_submit(io);
 561                                 else
 562                                         new_gfp_flags |= __GFP_NOFAIL;
 563                                 memalloc_retry_wait(gfp_flags);
 564                                 gfp_flags = new_gfp_flags;
 565                                 goto retry_encrypt;
 566                         }
 567
 568                         printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
 569                         folio_redirty_for_writepage(wbc, folio);
 570                         do {
 571                                 if (buffer_async_write(bh)) {
 572                                         clear_buffer_async_write(bh);
 573                                         set_buffer_dirty(bh);
 574                                 }
 575                                 bh = bh->b_this_page;
 576                         } while (bh != head);
 577
 578                         return ret;
 579                 }
 580                 io_folio = page_folio(bounce_page);
 581         }
 582
 583         __folio_start_writeback(folio, keep_towrite);
 584
 585         /* Now submit buffers to write */
 586         do {
 587                 if (!buffer_async_write(bh))
 588                         continue;
 589                 io_submit_add_bh(io, inode, folio, io_folio, bh);
 590         } while ((bh = bh->b_this_page) != head);
 591
 592         return 0;
 593 }