fs/ext4/page-io.c

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This source file includes following definitions.
ext4_init_pageio
ext4_exit_pageio
buffer_io_error
ext4_finish_bio
ext4_release_io_end
ext4_end_io
dump_completed_IO
ext4_add_complete_io
ext4_do_flush_completed_IO
ext4_end_io_rsv_work
ext4_init_io_end
ext4_put_io_end_defer
ext4_put_io_end
ext4_get_io_end
ext4_end_bio
ext4_io_submit
ext4_io_submit_init
io_submit_init_bio
io_submit_add_bh
ext4_bio_write_page
   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 
  35 int __init ext4_init_pageio(void)
  36 {
  37         io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
  38         if (io_end_cachep == NULL)
  39                 return -ENOMEM;
  40         return 0;
  41 }
  42 
  43 void ext4_exit_pageio(void)
  44 {
  45         kmem_cache_destroy(io_end_cachep);
  46 }
  47 
  48 /*
  49  * Print an buffer I/O error compatible with the fs/buffer.c.  This
  50  * provides compatibility with dmesg scrapers that look for a specific
  51  * buffer I/O error message.  We really need a unified error reporting
  52  * structure to userspace ala Digital Unix's uerf system, but it's
  53  * probably not going to happen in my lifetime, due to LKML politics...
  54  */
  55 static void buffer_io_error(struct buffer_head *bh)
  56 {
  57         printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n",
  58                        bh->b_bdev,
  59                         (unsigned long long)bh->b_blocknr);
  60 }
  61 
  62 static void ext4_finish_bio(struct bio *bio)
  63 {
  64         struct bio_vec *bvec;
  65         struct bvec_iter_all iter_all;
  66 
  67         bio_for_each_segment_all(bvec, bio, iter_all) {
  68                 struct page *page = bvec->bv_page;
  69                 struct page *bounce_page = NULL;
  70                 struct buffer_head *bh, *head;
  71                 unsigned bio_start = bvec->bv_offset;
  72                 unsigned bio_end = bio_start + bvec->bv_len;
  73                 unsigned under_io = 0;
  74                 unsigned long flags;
  75 
  76                 if (!page)
  77                         continue;
  78 
  79                 if (fscrypt_is_bounce_page(page)) {
  80                         bounce_page = page;
  81                         page = fscrypt_pagecache_page(bounce_page);
  82                 }
  83 
  84                 if (bio->bi_status) {
  85                         SetPageError(page);
  86                         mapping_set_error(page->mapping, -EIO);
  87                 }
  88                 bh = head = page_buffers(page);
  89                 /*
  90                  * We check all buffers in the page under BH_Uptodate_Lock
  91                  * to avoid races with other end io clearing async_write flags
  92                  */
  93                 local_irq_save(flags);
  94                 bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
  95                 do {
  96                         if (bh_offset(bh) < bio_start ||
  97                             bh_offset(bh) + bh->b_size > bio_end) {
  98                                 if (buffer_async_write(bh))
  99                                         under_io++;
 100                                 continue;
 101                         }
 102                         clear_buffer_async_write(bh);
 103                         if (bio->bi_status)
 104                                 buffer_io_error(bh);
 105                 } while ((bh = bh->b_this_page) != head);
 106                 bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
 107                 local_irq_restore(flags);
 108                 if (!under_io) {
 109                         fscrypt_free_bounce_page(bounce_page);
 110                         end_page_writeback(page);
 111                 }
 112         }
 113 }
 114 
 115 static void ext4_release_io_end(ext4_io_end_t *io_end)
 116 {
 117         struct bio *bio, *next_bio;
 118 
 119         BUG_ON(!list_empty(&io_end->list));
 120         BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
 121         WARN_ON(io_end->handle);
 122 
 123         for (bio = io_end->bio; bio; bio = next_bio) {
 124                 next_bio = bio->bi_private;
 125                 ext4_finish_bio(bio);
 126                 bio_put(bio);
 127         }
 128         kmem_cache_free(io_end_cachep, io_end);
 129 }
 130 
 131 /*
 132  * Check a range of space and convert unwritten extents to written. Note that
 133  * we are protected from truncate touching same part of extent tree by the
 134  * fact that truncate code waits for all DIO to finish (thus exclusion from
 135  * direct IO is achieved) and also waits for PageWriteback bits. Thus we
 136  * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
 137  * completed (happens from ext4_free_ioend()).
 138  */
 139 static int ext4_end_io(ext4_io_end_t *io)
 140 {
 141         struct inode *inode = io->inode;
 142         loff_t offset = io->offset;
 143         ssize_t size = io->size;
 144         handle_t *handle = io->handle;
 145         int ret = 0;
 146 
 147         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
 148                    "list->prev 0x%p\n",
 149                    io, inode->i_ino, io->list.next, io->list.prev);
 150 
 151         io->handle = NULL;      /* Following call will use up the handle */
 152         ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
 153         if (ret < 0 && !ext4_forced_shutdown(EXT4_SB(inode->i_sb))) {
 154                 ext4_msg(inode->i_sb, KERN_EMERG,
 155                          "failed to convert unwritten extents to written "
 156                          "extents -- potential data loss!  "
 157                          "(inode %lu, offset %llu, size %zd, error %d)",
 158                          inode->i_ino, offset, size, ret);
 159         }
 160         ext4_clear_io_unwritten_flag(io);
 161         ext4_release_io_end(io);
 162         return ret;
 163 }
 164 
 165 static void dump_completed_IO(struct inode *inode, struct list_head *head)
 166 {
 167 #ifdef  EXT4FS_DEBUG
 168         struct list_head *cur, *before, *after;
 169         ext4_io_end_t *io, *io0, *io1;
 170 
 171         if (list_empty(head))
 172                 return;
 173 
 174         ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
 175         list_for_each_entry(io, head, list) {
 176                 cur = &io->list;
 177                 before = cur->prev;
 178                 io0 = container_of(before, ext4_io_end_t, list);
 179                 after = cur->next;
 180                 io1 = container_of(after, ext4_io_end_t, list);
 181 
 182                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 183                             io, inode->i_ino, io0, io1);
 184         }
 185 #endif
 186 }
 187 
 188 /* Add the io_end to per-inode completed end_io list. */
 189 static void ext4_add_complete_io(ext4_io_end_t *io_end)
 190 {
 191         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 192         struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
 193         struct workqueue_struct *wq;
 194         unsigned long flags;
 195 
 196         /* Only reserved conversions from writeback should enter here */
 197         WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 198         WARN_ON(!io_end->handle && sbi->s_journal);
 199         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 200         wq = sbi->rsv_conversion_wq;
 201         if (list_empty(&ei->i_rsv_conversion_list))
 202                 queue_work(wq, &ei->i_rsv_conversion_work);
 203         list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
 204         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 205 }
 206 
 207 static int ext4_do_flush_completed_IO(struct inode *inode,
 208                                       struct list_head *head)
 209 {
 210         ext4_io_end_t *io;
 211         struct list_head unwritten;
 212         unsigned long flags;
 213         struct ext4_inode_info *ei = EXT4_I(inode);
 214         int err, ret = 0;
 215 
 216         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 217         dump_completed_IO(inode, head);
 218         list_replace_init(head, &unwritten);
 219         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 220 
 221         while (!list_empty(&unwritten)) {
 222                 io = list_entry(unwritten.next, ext4_io_end_t, list);
 223                 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
 224                 list_del_init(&io->list);
 225 
 226                 err = ext4_end_io(io);
 227                 if (unlikely(!ret && err))
 228                         ret = err;
 229         }
 230         return ret;
 231 }
 232 
 233 /*
 234  * work on completed IO, to convert unwritten extents to extents
 235  */
 236 void ext4_end_io_rsv_work(struct work_struct *work)
 237 {
 238         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 239                                                   i_rsv_conversion_work);
 240         ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
 241 }
 242 
 243 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 244 {
 245         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 246         if (io) {
 247                 io->inode = inode;
 248                 INIT_LIST_HEAD(&io->list);
 249                 atomic_set(&io->count, 1);
 250         }
 251         return io;
 252 }
 253 
 254 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
 255 {
 256         if (atomic_dec_and_test(&io_end->count)) {
 257                 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
 258                         ext4_release_io_end(io_end);
 259                         return;
 260                 }
 261                 ext4_add_complete_io(io_end);
 262         }
 263 }
 264 
 265 int ext4_put_io_end(ext4_io_end_t *io_end)
 266 {
 267         int err = 0;
 268 
 269         if (atomic_dec_and_test(&io_end->count)) {
 270                 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 271                         err = ext4_convert_unwritten_extents(io_end->handle,
 272                                                 io_end->inode, io_end->offset,
 273                                                 io_end->size);
 274                         io_end->handle = NULL;
 275                         ext4_clear_io_unwritten_flag(io_end);
 276                 }
 277                 ext4_release_io_end(io_end);
 278         }
 279         return err;
 280 }
 281 
 282 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
 283 {
 284         atomic_inc(&io_end->count);
 285         return io_end;
 286 }
 287 
 288 /* BIO completion function for page writeback */
 289 static void ext4_end_bio(struct bio *bio)
 290 {
 291         ext4_io_end_t *io_end = bio->bi_private;
 292         sector_t bi_sector = bio->bi_iter.bi_sector;
 293         char b[BDEVNAME_SIZE];
 294 
 295         if (WARN_ONCE(!io_end, "io_end is NULL: %s: sector %Lu len %u err %d\n",
 296                       bio_devname(bio, b),
 297                       (long long) bio->bi_iter.bi_sector,
 298                       (unsigned) bio_sectors(bio),
 299                       bio->bi_status)) {
 300                 ext4_finish_bio(bio);
 301                 bio_put(bio);
 302                 return;
 303         }
 304         bio->bi_end_io = NULL;
 305 
 306         if (bio->bi_status) {
 307                 struct inode *inode = io_end->inode;
 308 
 309                 ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
 310                              "(offset %llu size %ld starting block %llu)",
 311                              bio->bi_status, inode->i_ino,
 312                              (unsigned long long) io_end->offset,
 313                              (long) io_end->size,
 314                              (unsigned long long)
 315                              bi_sector >> (inode->i_blkbits - 9));
 316                 mapping_set_error(inode->i_mapping,
 317                                 blk_status_to_errno(bio->bi_status));
 318         }
 319 
 320         if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 321                 /*
 322                  * Link bio into list hanging from io_end. We have to do it
 323                  * atomically as bio completions can be racing against each
 324                  * other.
 325                  */
 326                 bio->bi_private = xchg(&io_end->bio, bio);
 327                 ext4_put_io_end_defer(io_end);
 328         } else {
 329                 /*
 330                  * Drop io_end reference early. Inode can get freed once
 331                  * we finish the bio.
 332                  */
 333                 ext4_put_io_end_defer(io_end);
 334                 ext4_finish_bio(bio);
 335                 bio_put(bio);
 336         }
 337 }
 338 
 339 void ext4_io_submit(struct ext4_io_submit *io)
 340 {
 341         struct bio *bio = io->io_bio;
 342 
 343         if (bio) {
 344                 int io_op_flags = io->io_wbc->sync_mode == WB_SYNC_ALL ?
 345                                   REQ_SYNC : 0;
 346                 io->io_bio->bi_write_hint = io->io_end->inode->i_write_hint;
 347                 bio_set_op_attrs(io->io_bio, REQ_OP_WRITE, io_op_flags);
 348                 submit_bio(io->io_bio);
 349         }
 350         io->io_bio = NULL;
 351 }
 352 
 353 void ext4_io_submit_init(struct ext4_io_submit *io,
 354                          struct writeback_control *wbc)
 355 {
 356         io->io_wbc = wbc;
 357         io->io_bio = NULL;
 358         io->io_end = NULL;
 359 }
 360 
 361 static int io_submit_init_bio(struct ext4_io_submit *io,
 362                               struct buffer_head *bh)
 363 {
 364         struct bio *bio;
 365 
 366         bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
 367         if (!bio)
 368                 return -ENOMEM;
 369         bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 370         bio_set_dev(bio, bh->b_bdev);
 371         bio->bi_end_io = ext4_end_bio;
 372         bio->bi_private = ext4_get_io_end(io->io_end);
 373         io->io_bio = bio;
 374         io->io_next_block = bh->b_blocknr;
 375         wbc_init_bio(io->io_wbc, bio);
 376         return 0;
 377 }
 378 
 379 static int io_submit_add_bh(struct ext4_io_submit *io,
 380                             struct inode *inode,
 381                             struct page *page,
 382                             struct buffer_head *bh)
 383 {
 384         int ret;
 385 
 386         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 387 submit_and_retry:
 388                 ext4_io_submit(io);
 389         }
 390         if (io->io_bio == NULL) {
 391                 ret = io_submit_init_bio(io, bh);
 392                 if (ret)
 393                         return ret;
 394                 io->io_bio->bi_write_hint = inode->i_write_hint;
 395         }
 396         ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
 397         if (ret != bh->b_size)
 398                 goto submit_and_retry;
 399         wbc_account_cgroup_owner(io->io_wbc, page, bh->b_size);
 400         io->io_next_block++;
 401         return 0;
 402 }
 403 
 404 int ext4_bio_write_page(struct ext4_io_submit *io,
 405                         struct page *page,
 406                         int len,
 407                         struct writeback_control *wbc,
 408                         bool keep_towrite)
 409 {
 410         struct page *bounce_page = NULL;
 411         struct inode *inode = page->mapping->host;
 412         unsigned block_start;
 413         struct buffer_head *bh, *head;
 414         int ret = 0;
 415         int nr_submitted = 0;
 416         int nr_to_submit = 0;
 417 
 418         BUG_ON(!PageLocked(page));
 419         BUG_ON(PageWriteback(page));
 420 
 421         if (keep_towrite)
 422                 set_page_writeback_keepwrite(page);
 423         else
 424                 set_page_writeback(page);
 425         ClearPageError(page);
 426 
 427         /*
 428          * Comments copied from block_write_full_page:
 429          *
 430          * The page straddles i_size.  It must be zeroed out on each and every
 431          * writepage invocation because it may be mmapped.  "A file is mapped
 432          * in multiples of the page size.  For a file that is not a multiple of
 433          * the page size, the remaining memory is zeroed when mapped, and
 434          * writes to that region are not written out to the file."
 435          */
 436         if (len < PAGE_SIZE)
 437                 zero_user_segment(page, len, PAGE_SIZE);
 438         /*
 439          * In the first loop we prepare and mark buffers to submit. We have to
 440          * mark all buffers in the page before submitting so that
 441          * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
 442          * on the first buffer finishes and we are still working on submitting
 443          * the second buffer.
 444          */
 445         bh = head = page_buffers(page);
 446         do {
 447                 block_start = bh_offset(bh);
 448                 if (block_start >= len) {
 449                         clear_buffer_dirty(bh);
 450                         set_buffer_uptodate(bh);
 451                         continue;
 452                 }
 453                 if (!buffer_dirty(bh) || buffer_delay(bh) ||
 454                     !buffer_mapped(bh) || buffer_unwritten(bh)) {
 455                         /* A hole? We can safely clear the dirty bit */
 456                         if (!buffer_mapped(bh))
 457                                 clear_buffer_dirty(bh);
 458                         if (io->io_bio)
 459                                 ext4_io_submit(io);
 460                         continue;
 461                 }
 462                 if (buffer_new(bh))
 463                         clear_buffer_new(bh);
 464                 set_buffer_async_write(bh);
 465                 nr_to_submit++;
 466         } while ((bh = bh->b_this_page) != head);
 467 
 468         bh = head = page_buffers(page);
 469 
 470         /*
 471          * If any blocks are being written to an encrypted file, encrypt them
 472          * into a bounce page.  For simplicity, just encrypt until the last
 473          * block which might be needed.  This may cause some unneeded blocks
 474          * (e.g. holes) to be unnecessarily encrypted, but this is rare and
 475          * can't happen in the common case of blocksize == PAGE_SIZE.
 476          */
 477         if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode) && nr_to_submit) {
 478                 gfp_t gfp_flags = GFP_NOFS;
 479                 unsigned int enc_bytes = round_up(len, i_blocksize(inode));
 480 
 481                 /*
 482                  * Since bounce page allocation uses a mempool, we can only use
 483                  * a waiting mask (i.e. request guaranteed allocation) on the
 484                  * first page of the bio.  Otherwise it can deadlock.
 485                  */
 486                 if (io->io_bio)
 487                         gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
 488         retry_encrypt:
 489                 bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes,
 490                                                                0, gfp_flags);
 491                 if (IS_ERR(bounce_page)) {
 492                         ret = PTR_ERR(bounce_page);
 493                         if (ret == -ENOMEM &&
 494                             (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
 495                                 gfp_flags = GFP_NOFS;
 496                                 if (io->io_bio)
 497                                         ext4_io_submit(io);
 498                                 else
 499                                         gfp_flags |= __GFP_NOFAIL;
 500                                 congestion_wait(BLK_RW_ASYNC, HZ/50);
 501                                 goto retry_encrypt;
 502                         }
 503                         bounce_page = NULL;
 504                         goto out;
 505                 }
 506         }
 507 
 508         /* Now submit buffers to write */
 509         do {
 510                 if (!buffer_async_write(bh))
 511                         continue;
 512                 ret = io_submit_add_bh(io, inode, bounce_page ?: page, bh);
 513                 if (ret) {
 514                         /*
 515                          * We only get here on ENOMEM.  Not much else
 516                          * we can do but mark the page as dirty, and
 517                          * better luck next time.
 518                          */
 519                         break;
 520                 }
 521                 nr_submitted++;
 522                 clear_buffer_dirty(bh);
 523         } while ((bh = bh->b_this_page) != head);
 524 
 525         /* Error stopped previous loop? Clean up buffers... */
 526         if (ret) {
 527         out:
 528                 fscrypt_free_bounce_page(bounce_page);
 529                 printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
 530                 redirty_page_for_writepage(wbc, page);
 531                 do {
 532                         clear_buffer_async_write(bh);
 533                         bh = bh->b_this_page;
 534                 } while (bh != head);
 535         }
 536         unlock_page(page);
 537         /* Nothing submitted - we have to end page writeback */
 538         if (!nr_submitted)
 539                 end_page_writeback(page);
 540         return ret;
 541 }
/* [<][>][^][v][top][bottom][index][help] */
root/fs/ext4/page-io.c

DEFINITIONS
