fs/ext4/page-io.c

   1 /*
   2  * linux/fs/ext4/page-io.c
   3  *
   4  * This contains the new page_io functions for ext4
   5  *
   6  * Written by Theodore Ts'o, 2010.
   7  */
   8
   9 #include <linux/fs.h>
  10 #include <linux/time.h>
  11 #include <linux/highuid.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/quotaops.h>
  14 #include <linux/string.h>
  15 #include <linux/buffer_head.h>
  16 #include <linux/writeback.h>
  17 #include <linux/pagevec.h>
  18 #include <linux/mpage.h>
  19 #include <linux/namei.h>
  20 #include <linux/uio.h>
  21 #include <linux/bio.h>
  22 #include <linux/workqueue.h>
  23 #include <linux/kernel.h>
  24 #include <linux/slab.h>
  25 #include <linux/mm.h>
  26 #include <linux/backing-dev.h>
  27
  28 #include "ext4_jbd2.h"
  29 #include "xattr.h"
  30 #include "acl.h"
  31
  32 static struct kmem_cache *io_end_cachep;
  33
  34 int __init ext4_init_pageio(void)
  35 {
  36         io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
  37         if (io_end_cachep == NULL)
  38                 return -ENOMEM;
  39         return 0;
  40 }
  41
  42 void ext4_exit_pageio(void)
  43 {
  44         kmem_cache_destroy(io_end_cachep);
  45 }
  46
  47 /*
  48  * Print an buffer I/O error compatible with the fs/buffer.c.  This
  49  * provides compatibility with dmesg scrapers that look for a specific
  50  * buffer I/O error message.  We really need a unified error reporting
  51  * structure to userspace ala Digital Unix's uerf system, but it's
  52  * probably not going to happen in my lifetime, due to LKML politics...
  53  */
  54 static void buffer_io_error(struct buffer_head *bh)
  55 {
  56         printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n",
  57                        bh->b_bdev,
  58                         (unsigned long long)bh->b_blocknr);
  59 }
  60
  61 static void ext4_finish_bio(struct bio *bio)
  62 {
  63         int i;
  64         struct bio_vec *bvec;
  65
  66         bio_for_each_segment_all(bvec, bio, i) {
  67                 struct page *page = bvec->bv_page;
  68 #ifdef CONFIG_EXT4_FS_ENCRYPTION
  69                 struct page *data_page = NULL;
  70                 struct ext4_crypto_ctx *ctx = NULL;
  71 #endif
  72                 struct buffer_head *bh, *head;
  73                 unsigned bio_start = bvec->bv_offset;
  74                 unsigned bio_end = bio_start + bvec->bv_len;
  75                 unsigned under_io = 0;
  76                 unsigned long flags;
  77
  78                 if (!page)
  79                         continue;
  80
  81 #ifdef CONFIG_EXT4_FS_ENCRYPTION
  82                 if (!page->mapping) {
  83                         /* The bounce data pages are unmapped. */
  84                         data_page = page;
  85                         ctx = (struct ext4_crypto_ctx *)page_private(data_page);
  86                         page = ctx->w.control_page;
  87                 }
  88 #endif
  89
  90                 if (bio->bi_error) {
  91                         SetPageError(page);
  92                         set_bit(AS_EIO, &page->mapping->flags);
  93                 }
  94                 bh = head = page_buffers(page);
  95                 /*
  96                  * We check all buffers in the page under BH_Uptodate_Lock
  97                  * to avoid races with other end io clearing async_write flags
  98                  */
  99                 local_irq_save(flags);
 100                 bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
 101                 do {
 102                         if (bh_offset(bh) < bio_start ||
 103                             bh_offset(bh) + bh->b_size > bio_end) {
 104                                 if (buffer_async_write(bh))
 105                                         under_io++;
 106                                 continue;
 107                         }
 108                         clear_buffer_async_write(bh);
 109                         if (bio->bi_error)
 110                                 buffer_io_error(bh);
 111                 } while ((bh = bh->b_this_page) != head);
 112                 bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
 113                 local_irq_restore(flags);
 114                 if (!under_io) {
 115 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 116                         if (ctx)
 117                                 ext4_restore_control_page(data_page);
 118 #endif
 119                         end_page_writeback(page);
 120                 }
 121         }
 122 }
 123
 124 static void ext4_release_io_end(ext4_io_end_t *io_end)
 125 {
 126         struct bio *bio, *next_bio;
 127
 128         BUG_ON(!list_empty(&io_end->list));
 129         BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
 130         WARN_ON(io_end->handle);
 131
 132         for (bio = io_end->bio; bio; bio = next_bio) {
 133                 next_bio = bio->bi_private;
 134                 ext4_finish_bio(bio);
 135                 bio_put(bio);
 136         }
 137         kmem_cache_free(io_end_cachep, io_end);
 138 }
 139
 140 /*
 141  * Check a range of space and convert unwritten extents to written. Note that
 142  * we are protected from truncate touching same part of extent tree by the
 143  * fact that truncate code waits for all DIO to finish (thus exclusion from
 144  * direct IO is achieved) and also waits for PageWriteback bits. Thus we
 145  * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
 146  * completed (happens from ext4_free_ioend()).
 147  */
 148 static int ext4_end_io(ext4_io_end_t *io)
 149 {
 150         struct inode *inode = io->inode;
 151         loff_t offset = io->offset;
 152         ssize_t size = io->size;
 153         handle_t *handle = io->handle;
 154         int ret = 0;
 155
 156         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
 157                    "list->prev 0x%p\n",
 158                    io, inode->i_ino, io->list.next, io->list.prev);
 159
 160         io->handle = NULL;      /* Following call will use up the handle */
 161         ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
 162         if (ret < 0) {
 163                 ext4_msg(inode->i_sb, KERN_EMERG,
 164                          "failed to convert unwritten extents to written "
 165                          "extents -- potential data loss!  "
 166                          "(inode %lu, offset %llu, size %zd, error %d)",
 167                          inode->i_ino, offset, size, ret);
 168         }
 169         ext4_clear_io_unwritten_flag(io);
 170         ext4_release_io_end(io);
 171         return ret;
 172 }
 173
 174 static void dump_completed_IO(struct inode *inode, struct list_head *head)
 175 {
 176 #ifdef  EXT4FS_DEBUG
 177         struct list_head *cur, *before, *after;
 178         ext4_io_end_t *io, *io0, *io1;
 179
 180         if (list_empty(head))
 181                 return;
 182
 183         ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
 184         list_for_each_entry(io, head, list) {
 185                 cur = &io->list;
 186                 before = cur->prev;
 187                 io0 = container_of(before, ext4_io_end_t, list);
 188                 after = cur->next;
 189                 io1 = container_of(after, ext4_io_end_t, list);
 190
 191                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 192                             io, inode->i_ino, io0, io1);
 193         }
 194 #endif
 195 }
 196
 197 /* Add the io_end to per-inode completed end_io list. */
 198 static void ext4_add_complete_io(ext4_io_end_t *io_end)
 199 {
 200         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 201         struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
 202         struct workqueue_struct *wq;
 203         unsigned long flags;
 204
 205         /* Only reserved conversions from writeback should enter here */
 206         WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 207         WARN_ON(!io_end->handle && sbi->s_journal);
 208         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 209         wq = sbi->rsv_conversion_wq;
 210         if (list_empty(&ei->i_rsv_conversion_list))
 211                 queue_work(wq, &ei->i_rsv_conversion_work);
 212         list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
 213         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 214 }
 215
 216 static int ext4_do_flush_completed_IO(struct inode *inode,
 217                                       struct list_head *head)
 218 {
 219         ext4_io_end_t *io;
 220         struct list_head unwritten;
 221         unsigned long flags;
 222         struct ext4_inode_info *ei = EXT4_I(inode);
 223         int err, ret = 0;
 224
 225         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 226         dump_completed_IO(inode, head);
 227         list_replace_init(head, &unwritten);
 228         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 229
 230         while (!list_empty(&unwritten)) {
 231                 io = list_entry(unwritten.next, ext4_io_end_t, list);
 232                 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
 233                 list_del_init(&io->list);
 234
 235                 err = ext4_end_io(io);
 236                 if (unlikely(!ret && err))
 237                         ret = err;
 238         }
 239         return ret;
 240 }
 241
 242 /*
 243  * work on completed IO, to convert unwritten extents to extents
 244  */
 245 void ext4_end_io_rsv_work(struct work_struct *work)
 246 {
 247         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 248                                                   i_rsv_conversion_work);
 249         ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
 250 }
 251
 252 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 253 {
 254         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 255         if (io) {
 256                 io->inode = inode;
 257                 INIT_LIST_HEAD(&io->list);
 258                 atomic_set(&io->count, 1);
 259         }
 260         return io;
 261 }
 262
 263 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
 264 {
 265         if (atomic_dec_and_test(&io_end->count)) {
 266                 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
 267                         ext4_release_io_end(io_end);
 268                         return;
 269                 }
 270                 ext4_add_complete_io(io_end);
 271         }
 272 }
 273
 274 int ext4_put_io_end(ext4_io_end_t *io_end)
 275 {
 276         int err = 0;
 277
 278         if (atomic_dec_and_test(&io_end->count)) {
 279                 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 280                         err = ext4_convert_unwritten_extents(io_end->handle,
 281                                                 io_end->inode, io_end->offset,
 282                                                 io_end->size);
 283                         io_end->handle = NULL;
 284                         ext4_clear_io_unwritten_flag(io_end);
 285                 }
 286                 ext4_release_io_end(io_end);
 287         }
 288         return err;
 289 }
 290
 291 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
 292 {
 293         atomic_inc(&io_end->count);
 294         return io_end;
 295 }
 296
 297 /* BIO completion function for page writeback */
 298 static void ext4_end_bio(struct bio *bio)
 299 {
 300         ext4_io_end_t *io_end = bio->bi_private;
 301         sector_t bi_sector = bio->bi_iter.bi_sector;
 302
 303         BUG_ON(!io_end);
 304         bio->bi_end_io = NULL;
 305
 306         if (bio->bi_error) {
 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_error, 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, bio->bi_error);
 317         }
 318
 319         if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 320                 /*
 321                  * Link bio into list hanging from io_end. We have to do it
 322                  * atomically as bio completions can be racing against each
 323                  * other.
 324                  */
 325                 bio->bi_private = xchg(&io_end->bio, bio);
 326                 ext4_put_io_end_defer(io_end);
 327         } else {
 328                 /*
 329                  * Drop io_end reference early. Inode can get freed once
 330                  * we finish the bio.
 331                  */
 332                 ext4_put_io_end_defer(io_end);
 333                 ext4_finish_bio(bio);
 334                 bio_put(bio);
 335         }
 336 }
 337
 338 void ext4_io_submit(struct ext4_io_submit *io)
 339 {
 340         struct bio *bio = io->io_bio;
 341
 342         if (bio) {
 343                 int io_op = io->io_wbc->sync_mode == WB_SYNC_ALL ?
 344                             WRITE_SYNC : WRITE;
 345                 bio_get(io->io_bio);
 346                 submit_bio(io_op, io->io_bio);
 347                 bio_put(io->io_bio);
 348         }
 349         io->io_bio = NULL;
 350 }
 351
 352 void ext4_io_submit_init(struct ext4_io_submit *io,
 353                          struct writeback_control *wbc)
 354 {
 355         io->io_wbc = wbc;
 356         io->io_bio = NULL;
 357         io->io_end = NULL;
 358 }
 359
 360 static int io_submit_init_bio(struct ext4_io_submit *io,
 361                               struct buffer_head *bh)
 362 {
 363         struct bio *bio;
 364
 365         bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
 366         if (!bio)
 367                 return -ENOMEM;
 368         wbc_init_bio(io->io_wbc, bio);
 369         bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 370         bio->bi_bdev = 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         return 0;
 376 }
 377
 378 static int io_submit_add_bh(struct ext4_io_submit *io,
 379                             struct inode *inode,
 380                             struct page *page,
 381                             struct buffer_head *bh)
 382 {
 383         int ret;
 384
 385         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 386 submit_and_retry:
 387                 ext4_io_submit(io);
 388         }
 389         if (io->io_bio == NULL) {
 390                 ret = io_submit_init_bio(io, bh);
 391                 if (ret)
 392                         return ret;
 393         }
 394         ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
 395         if (ret != bh->b_size)
 396                 goto submit_and_retry;
 397         wbc_account_io(io->io_wbc, page, bh->b_size);
 398         io->io_next_block++;
 399         return 0;
 400 }
 401
 402 int ext4_bio_write_page(struct ext4_io_submit *io,
 403                         struct page *page,
 404                         int len,
 405                         struct writeback_control *wbc,
 406                         bool keep_towrite)
 407 {
 408         struct page *data_page = NULL;
 409         struct inode *inode = page->mapping->host;
 410         unsigned block_start, blocksize;
 411         struct buffer_head *bh, *head;
 412         int ret = 0;
 413         int nr_submitted = 0;
 414         int nr_to_submit = 0;
 415
 416         blocksize = 1 << inode->i_blkbits;
 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                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 465                 }
 466                 set_buffer_async_write(bh);
 467                 nr_to_submit++;
 468         } while ((bh = bh->b_this_page) != head);
 469
 470         bh = head = page_buffers(page);
 471
 472         if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
 473             nr_to_submit) {
 474                 gfp_t gfp_flags = GFP_NOFS;
 475
 476         retry_encrypt:
 477                 data_page = ext4_encrypt(inode, page, gfp_flags);
 478                 if (IS_ERR(data_page)) {
 479                         ret = PTR_ERR(data_page);
 480                         if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
 481                                 if (io->io_bio) {
 482                                         ext4_io_submit(io);
 483                                         congestion_wait(BLK_RW_ASYNC, HZ/50);
 484                                 }
 485                                 gfp_flags |= __GFP_NOFAIL;
 486                                 goto retry_encrypt;
 487                         }
 488                         data_page = NULL;
 489                         goto out;
 490                 }
 491         }
 492
 493         /* Now submit buffers to write */
 494         do {
 495                 if (!buffer_async_write(bh))
 496                         continue;
 497                 ret = io_submit_add_bh(io, inode,
 498                                        data_page ? data_page : page, bh);
 499                 if (ret) {
 500                         /*
 501                          * We only get here on ENOMEM.  Not much else
 502                          * we can do but mark the page as dirty, and
 503                          * better luck next time.
 504                          */
 505                         break;
 506                 }
 507                 nr_submitted++;
 508                 clear_buffer_dirty(bh);
 509         } while ((bh = bh->b_this_page) != head);
 510
 511         /* Error stopped previous loop? Clean up buffers... */
 512         if (ret) {
 513         out:
 514                 if (data_page)
 515                         ext4_restore_control_page(data_page);
 516                 printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
 517                 redirty_page_for_writepage(wbc, page);
 518                 do {
 519                         clear_buffer_async_write(bh);
 520                         bh = bh->b_this_page;
 521                 } while (bh != head);
 522         }
 523         unlock_page(page);
 524         /* Nothing submitted - we have to end page writeback */
 525         if (!nr_submitted)
 526                 end_page_writeback(page);
 527         return ret;
 528 }