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/backing-dev.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 bio_vec *bvec;
 103         struct bvec_iter_all iter_all;
 104
 105         bio_for_each_segment_all(bvec, bio, iter_all) {
 106                 struct page *page = bvec->bv_page;
 107                 struct page *bounce_page = NULL;
 108                 struct buffer_head *bh, *head;
 109                 unsigned bio_start = bvec->bv_offset;
 110                 unsigned bio_end = bio_start + bvec->bv_len;
 111                 unsigned under_io = 0;
 112                 unsigned long flags;
 113
 114                 if (!page)
 115                         continue;
 116
 117                 if (fscrypt_is_bounce_page(page)) {
 118                         bounce_page = page;
 119                         page = fscrypt_pagecache_page(bounce_page);
 120                 }
 121
 122                 if (bio->bi_status) {
 123                         SetPageError(page);
 124                         mapping_set_error(page->mapping, -EIO);
 125                 }
 126                 bh = head = page_buffers(page);
 127                 /*
 128                  * We check all buffers in the page under b_uptodate_lock
 129                  * to avoid races with other end io clearing async_write flags
 130                  */
 131                 spin_lock_irqsave(&head->b_uptodate_lock, flags);
 132                 do {
 133                         if (bh_offset(bh) < bio_start ||
 134                             bh_offset(bh) + bh->b_size > bio_end) {
 135                                 if (buffer_async_write(bh))
 136                                         under_io++;
 137                                 continue;
 138                         }
 139                         clear_buffer_async_write(bh);
 140                         if (bio->bi_status)
 141                                 buffer_io_error(bh);
 142                 } while ((bh = bh->b_this_page) != head);
 143                 spin_unlock_irqrestore(&head->b_uptodate_lock, flags);
 144                 if (!under_io) {
 145                         fscrypt_free_bounce_page(bounce_page);
 146                         end_page_writeback(page);
 147                 }
 148         }
 149 }
 150
 151 static void ext4_release_io_end(ext4_io_end_t *io_end)
 152 {
 153         struct bio *bio, *next_bio;
 154
 155         BUG_ON(!list_empty(&io_end->list));
 156         BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
 157         WARN_ON(io_end->handle);
 158
 159         for (bio = io_end->bio; bio; bio = next_bio) {
 160                 next_bio = bio->bi_private;
 161                 ext4_finish_bio(bio);
 162                 bio_put(bio);
 163         }
 164         ext4_free_io_end_vec(io_end);
 165         kmem_cache_free(io_end_cachep, io_end);
 166 }
 167
 168 /*
 169  * Check a range of space and convert unwritten extents to written. Note that
 170  * we are protected from truncate touching same part of extent tree by the
 171  * fact that truncate code waits for all DIO to finish (thus exclusion from
 172  * direct IO is achieved) and also waits for PageWriteback bits. Thus we
 173  * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
 174  * completed (happens from ext4_free_ioend()).
 175  */
 176 static int ext4_end_io_end(ext4_io_end_t *io_end)
 177 {
 178         struct inode *inode = io_end->inode;
 179         handle_t *handle = io_end->handle;
 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         io_end->handle = NULL;  /* Following call will use up the handle */
 187         ret = ext4_convert_unwritten_io_end_vec(handle, io_end);
 188         if (ret < 0 && !ext4_forced_shutdown(EXT4_SB(inode->i_sb))) {
 189                 ext4_msg(inode->i_sb, KERN_EMERG,
 190                          "failed to convert unwritten extents to written "
 191                          "extents -- potential data loss!  "
 192                          "(inode %lu, error %d)", inode->i_ino, ret);
 193         }
 194         ext4_clear_io_unwritten_flag(io_end);
 195         ext4_release_io_end(io_end);
 196         return ret;
 197 }
 198
 199 static void dump_completed_IO(struct inode *inode, struct list_head *head)
 200 {
 201 #ifdef  EXT4FS_DEBUG
 202         struct list_head *cur, *before, *after;
 203         ext4_io_end_t *io_end, *io_end0, *io_end1;
 204
 205         if (list_empty(head))
 206                 return;
 207
 208         ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
 209         list_for_each_entry(io_end, head, list) {
 210                 cur = &io_end->list;
 211                 before = cur->prev;
 212                 io_end0 = container_of(before, ext4_io_end_t, list);
 213                 after = cur->next;
 214                 io_end1 = container_of(after, ext4_io_end_t, list);
 215
 216                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 217                             io_end, inode->i_ino, io_end0, io_end1);
 218         }
 219 #endif
 220 }
 221
 222 /* Add the io_end to per-inode completed end_io list. */
 223 static void ext4_add_complete_io(ext4_io_end_t *io_end)
 224 {
 225         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 226         struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
 227         struct workqueue_struct *wq;
 228         unsigned long flags;
 229
 230         /* Only reserved conversions from writeback should enter here */
 231         WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 232         WARN_ON(!io_end->handle && sbi->s_journal);
 233         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 234         wq = sbi->rsv_conversion_wq;
 235         if (list_empty(&ei->i_rsv_conversion_list))
 236                 queue_work(wq, &ei->i_rsv_conversion_work);
 237         list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
 238         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 239 }
 240
 241 static int ext4_do_flush_completed_IO(struct inode *inode,
 242                                       struct list_head *head)
 243 {
 244         ext4_io_end_t *io_end;
 245         struct list_head unwritten;
 246         unsigned long flags;
 247         struct ext4_inode_info *ei = EXT4_I(inode);
 248         int err, ret = 0;
 249
 250         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 251         dump_completed_IO(inode, head);
 252         list_replace_init(head, &unwritten);
 253         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 254
 255         while (!list_empty(&unwritten)) {
 256                 io_end = list_entry(unwritten.next, ext4_io_end_t, list);
 257                 BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 258                 list_del_init(&io_end->list);
 259
 260                 err = ext4_end_io_end(io_end);
 261                 if (unlikely(!ret && err))
 262                         ret = err;
 263         }
 264         return ret;
 265 }
 266
 267 /*
 268  * work on completed IO, to convert unwritten extents to extents
 269  */
 270 void ext4_end_io_rsv_work(struct work_struct *work)
 271 {
 272         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 273                                                   i_rsv_conversion_work);
 274         ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
 275 }
 276
 277 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 278 {
 279         ext4_io_end_t *io_end = kmem_cache_zalloc(io_end_cachep, flags);
 280
 281         if (io_end) {
 282                 io_end->inode = inode;
 283                 INIT_LIST_HEAD(&io_end->list);
 284                 INIT_LIST_HEAD(&io_end->list_vec);
 285                 atomic_set(&io_end->count, 1);
 286         }
 287         return io_end;
 288 }
 289
 290 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
 291 {
 292         if (atomic_dec_and_test(&io_end->count)) {
 293                 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) ||
 294                                 list_empty(&io_end->list_vec)) {
 295                         ext4_release_io_end(io_end);
 296                         return;
 297                 }
 298                 ext4_add_complete_io(io_end);
 299         }
 300 }
 301
 302 int ext4_put_io_end(ext4_io_end_t *io_end)
 303 {
 304         int err = 0;
 305
 306         if (atomic_dec_and_test(&io_end->count)) {
 307                 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 308                         err = ext4_convert_unwritten_io_end_vec(io_end->handle,
 309                                                                 io_end);
 310                         io_end->handle = NULL;
 311                         ext4_clear_io_unwritten_flag(io_end);
 312                 }
 313                 ext4_release_io_end(io_end);
 314         }
 315         return err;
 316 }
 317
 318 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
 319 {
 320         atomic_inc(&io_end->count);
 321         return io_end;
 322 }
 323
 324 /* BIO completion function for page writeback */
 325 static void ext4_end_bio(struct bio *bio)
 326 {
 327         ext4_io_end_t *io_end = bio->bi_private;
 328         sector_t bi_sector = bio->bi_iter.bi_sector;
 329         char b[BDEVNAME_SIZE];
 330
 331         if (WARN_ONCE(!io_end, "io_end is NULL: %s: sector %Lu len %u err %d\n",
 332                       bio_devname(bio, b),
 333                       (long long) bio->bi_iter.bi_sector,
 334                       (unsigned) bio_sectors(bio),
 335                       bio->bi_status)) {
 336                 ext4_finish_bio(bio);
 337                 bio_put(bio);
 338                 return;
 339         }
 340         bio->bi_end_io = NULL;
 341
 342         if (bio->bi_status) {
 343                 struct inode *inode = io_end->inode;
 344
 345                 ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
 346                              "starting block %llu)",
 347                              bio->bi_status, inode->i_ino,
 348                              (unsigned long long)
 349                              bi_sector >> (inode->i_blkbits - 9));
 350                 mapping_set_error(inode->i_mapping,
 351                                 blk_status_to_errno(bio->bi_status));
 352         }
 353
 354         if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 355                 /*
 356                  * Link bio into list hanging from io_end. We have to do it
 357                  * atomically as bio completions can be racing against each
 358                  * other.
 359                  */
 360                 bio->bi_private = xchg(&io_end->bio, bio);
 361                 ext4_put_io_end_defer(io_end);
 362         } else {
 363                 /*
 364                  * Drop io_end reference early. Inode can get freed once
 365                  * we finish the bio.
 366                  */
 367                 ext4_put_io_end_defer(io_end);
 368                 ext4_finish_bio(bio);
 369                 bio_put(bio);
 370         }
 371 }
 372
 373 void ext4_io_submit(struct ext4_io_submit *io)
 374 {
 375         struct bio *bio = io->io_bio;
 376
 377         if (bio) {
 378                 int io_op_flags = io->io_wbc->sync_mode == WB_SYNC_ALL ?
 379                                   REQ_SYNC : 0;
 380                 io->io_bio->bi_write_hint = io->io_end->inode->i_write_hint;
 381                 bio_set_op_attrs(io->io_bio, REQ_OP_WRITE, io_op_flags);
 382                 submit_bio(io->io_bio);
 383         }
 384         io->io_bio = NULL;
 385 }
 386
 387 void ext4_io_submit_init(struct ext4_io_submit *io,
 388                          struct writeback_control *wbc)
 389 {
 390         io->io_wbc = wbc;
 391         io->io_bio = NULL;
 392         io->io_end = NULL;
 393 }
 394
 395 static void io_submit_init_bio(struct ext4_io_submit *io,
 396                                struct buffer_head *bh)
 397 {
 398         struct bio *bio;
 399
 400         /*
 401          * bio_alloc will _always_ be able to allocate a bio if
 402          * __GFP_DIRECT_RECLAIM is set, see comments for bio_alloc_bioset().
 403          */
 404         bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
 405         bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 406         bio_set_dev(bio, bh->b_bdev);
 407         bio->bi_end_io = ext4_end_bio;
 408         bio->bi_private = ext4_get_io_end(io->io_end);
 409         io->io_bio = bio;
 410         io->io_next_block = bh->b_blocknr;
 411         wbc_init_bio(io->io_wbc, bio);
 412 }
 413
 414 static void io_submit_add_bh(struct ext4_io_submit *io,
 415                              struct inode *inode,
 416                              struct page *page,
 417                              struct buffer_head *bh)
 418 {
 419         int ret;
 420
 421         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 422 submit_and_retry:
 423                 ext4_io_submit(io);
 424         }
 425         if (io->io_bio == NULL) {
 426                 io_submit_init_bio(io, bh);
 427                 io->io_bio->bi_write_hint = inode->i_write_hint;
 428         }
 429         ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
 430         if (ret != bh->b_size)
 431                 goto submit_and_retry;
 432         wbc_account_cgroup_owner(io->io_wbc, page, bh->b_size);
 433         io->io_next_block++;
 434 }
 435
 436 int ext4_bio_write_page(struct ext4_io_submit *io,
 437                         struct page *page,
 438                         int len,
 439                         struct writeback_control *wbc,
 440                         bool keep_towrite)
 441 {
 442         struct page *bounce_page = NULL;
 443         struct inode *inode = page->mapping->host;
 444         unsigned block_start;
 445         struct buffer_head *bh, *head;
 446         int ret = 0;
 447         int nr_submitted = 0;
 448         int nr_to_submit = 0;
 449
 450         BUG_ON(!PageLocked(page));
 451         BUG_ON(PageWriteback(page));
 452
 453         if (keep_towrite)
 454                 set_page_writeback_keepwrite(page);
 455         else
 456                 set_page_writeback(page);
 457         ClearPageError(page);
 458
 459         /*
 460          * Comments copied from block_write_full_page:
 461          *
 462          * The page straddles i_size.  It must be zeroed out on each and every
 463          * writepage invocation because it may be mmapped.  "A file is mapped
 464          * in multiples of the page size.  For a file that is not a multiple of
 465          * the page size, the remaining memory is zeroed when mapped, and
 466          * writes to that region are not written out to the file."
 467          */
 468         if (len < PAGE_SIZE)
 469                 zero_user_segment(page, len, PAGE_SIZE);
 470         /*
 471          * In the first loop we prepare and mark buffers to submit. We have to
 472          * mark all buffers in the page before submitting so that
 473          * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
 474          * on the first buffer finishes and we are still working on submitting
 475          * the second buffer.
 476          */
 477         bh = head = page_buffers(page);
 478         do {
 479                 block_start = bh_offset(bh);
 480                 if (block_start >= len) {
 481                         clear_buffer_dirty(bh);
 482                         set_buffer_uptodate(bh);
 483                         continue;
 484                 }
 485                 if (!buffer_dirty(bh) || buffer_delay(bh) ||
 486                     !buffer_mapped(bh) || buffer_unwritten(bh)) {
 487                         /* A hole? We can safely clear the dirty bit */
 488                         if (!buffer_mapped(bh))
 489                                 clear_buffer_dirty(bh);
 490                         if (io->io_bio)
 491                                 ext4_io_submit(io);
 492                         continue;
 493                 }
 494                 if (buffer_new(bh))
 495                         clear_buffer_new(bh);
 496                 set_buffer_async_write(bh);
 497                 nr_to_submit++;
 498         } while ((bh = bh->b_this_page) != head);
 499
 500         bh = head = page_buffers(page);
 501
 502         /*
 503          * If any blocks are being written to an encrypted file, encrypt them
 504          * into a bounce page.  For simplicity, just encrypt until the last
 505          * block which might be needed.  This may cause some unneeded blocks
 506          * (e.g. holes) to be unnecessarily encrypted, but this is rare and
 507          * can't happen in the common case of blocksize == PAGE_SIZE.
 508          */
 509         if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode) && nr_to_submit) {
 510                 gfp_t gfp_flags = GFP_NOFS;
 511                 unsigned int enc_bytes = round_up(len, i_blocksize(inode));
 512
 513                 /*
 514                  * Since bounce page allocation uses a mempool, we can only use
 515                  * a waiting mask (i.e. request guaranteed allocation) on the
 516                  * first page of the bio.  Otherwise it can deadlock.
 517                  */
 518                 if (io->io_bio)
 519                         gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
 520         retry_encrypt:
 521                 bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes,
 522                                                                0, gfp_flags);
 523                 if (IS_ERR(bounce_page)) {
 524                         ret = PTR_ERR(bounce_page);
 525                         if (ret == -ENOMEM &&
 526                             (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
 527                                 gfp_flags = GFP_NOFS;
 528                                 if (io->io_bio)
 529                                         ext4_io_submit(io);
 530                                 else
 531                                         gfp_flags |= __GFP_NOFAIL;
 532                                 congestion_wait(BLK_RW_ASYNC, HZ/50);
 533                                 goto retry_encrypt;
 534                         }
 535
 536                         printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
 537                         redirty_page_for_writepage(wbc, page);
 538                         do {
 539                                 clear_buffer_async_write(bh);
 540                                 bh = bh->b_this_page;
 541                         } while (bh != head);
 542                         goto unlock;
 543                 }
 544         }
 545
 546         /* Now submit buffers to write */
 547         do {
 548                 if (!buffer_async_write(bh))
 549                         continue;
 550                 io_submit_add_bh(io, inode,
 551                                  bounce_page ? bounce_page : page, bh);
 552                 nr_submitted++;
 553                 clear_buffer_dirty(bh);
 554         } while ((bh = bh->b_this_page) != head);
 555
 556 unlock:
 557         unlock_page(page);
 558         /* Nothing submitted - we have to end page writeback */
 559         if (!nr_submitted)
 560                 end_page_writeback(page);
 561         return ret;
 562 }