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
  27 #include "ext4_jbd2.h"
  28 #include "xattr.h"
  29 #include "acl.h"
  30
  31 static struct kmem_cache *io_end_cachep;
  32
  33 int __init ext4_init_pageio(void)
  34 {
  35         io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
  36         if (io_end_cachep == NULL)
  37                 return -ENOMEM;
  38         return 0;
  39 }
  40
  41 void ext4_exit_pageio(void)
  42 {
  43         kmem_cache_destroy(io_end_cachep);
  44 }
  45
  46 /*
  47  * Print an buffer I/O error compatible with the fs/buffer.c.  This
  48  * provides compatibility with dmesg scrapers that look for a specific
  49  * buffer I/O error message.  We really need a unified error reporting
  50  * structure to userspace ala Digital Unix's uerf system, but it's
  51  * probably not going to happen in my lifetime, due to LKML politics...
  52  */
  53 static void buffer_io_error(struct buffer_head *bh)
  54 {
  55         char b[BDEVNAME_SIZE];
  56         printk_ratelimited(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
  57                         bdevname(bh->b_bdev, b),
  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         if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
 133                 wake_up_all(ext4_ioend_wq(io_end->inode));
 134
 135         for (bio = io_end->bio; bio; bio = next_bio) {
 136                 next_bio = bio->bi_private;
 137                 ext4_finish_bio(bio);
 138                 bio_put(bio);
 139         }
 140         kmem_cache_free(io_end_cachep, io_end);
 141 }
 142
 143 static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
 144 {
 145         struct inode *inode = io_end->inode;
 146
 147         io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
 148         /* Wake up anyone waiting on unwritten extent conversion */
 149         if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
 150                 wake_up_all(ext4_ioend_wq(inode));
 151 }
 152
 153 /*
 154  * Check a range of space and convert unwritten extents to written. Note that
 155  * we are protected from truncate touching same part of extent tree by the
 156  * fact that truncate code waits for all DIO to finish (thus exclusion from
 157  * direct IO is achieved) and also waits for PageWriteback bits. Thus we
 158  * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
 159  * completed (happens from ext4_free_ioend()).
 160  */
 161 static int ext4_end_io(ext4_io_end_t *io)
 162 {
 163         struct inode *inode = io->inode;
 164         loff_t offset = io->offset;
 165         ssize_t size = io->size;
 166         handle_t *handle = io->handle;
 167         int ret = 0;
 168
 169         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
 170                    "list->prev 0x%p\n",
 171                    io, inode->i_ino, io->list.next, io->list.prev);
 172
 173         io->handle = NULL;      /* Following call will use up the handle */
 174         ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
 175         if (ret < 0) {
 176                 ext4_msg(inode->i_sb, KERN_EMERG,
 177                          "failed to convert unwritten extents to written "
 178                          "extents -- potential data loss!  "
 179                          "(inode %lu, offset %llu, size %zd, error %d)",
 180                          inode->i_ino, offset, size, ret);
 181         }
 182         ext4_clear_io_unwritten_flag(io);
 183         ext4_release_io_end(io);
 184         return ret;
 185 }
 186
 187 static void dump_completed_IO(struct inode *inode, struct list_head *head)
 188 {
 189 #ifdef  EXT4FS_DEBUG
 190         struct list_head *cur, *before, *after;
 191         ext4_io_end_t *io, *io0, *io1;
 192
 193         if (list_empty(head))
 194                 return;
 195
 196         ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
 197         list_for_each_entry(io, head, list) {
 198                 cur = &io->list;
 199                 before = cur->prev;
 200                 io0 = container_of(before, ext4_io_end_t, list);
 201                 after = cur->next;
 202                 io1 = container_of(after, ext4_io_end_t, list);
 203
 204                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 205                             io, inode->i_ino, io0, io1);
 206         }
 207 #endif
 208 }
 209
 210 /* Add the io_end to per-inode completed end_io list. */
 211 static void ext4_add_complete_io(ext4_io_end_t *io_end)
 212 {
 213         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 214         struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
 215         struct workqueue_struct *wq;
 216         unsigned long flags;
 217
 218         /* Only reserved conversions from writeback should enter here */
 219         WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 220         WARN_ON(!io_end->handle && sbi->s_journal);
 221         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 222         wq = sbi->rsv_conversion_wq;
 223         if (list_empty(&ei->i_rsv_conversion_list))
 224                 queue_work(wq, &ei->i_rsv_conversion_work);
 225         list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
 226         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 227 }
 228
 229 static int ext4_do_flush_completed_IO(struct inode *inode,
 230                                       struct list_head *head)
 231 {
 232         ext4_io_end_t *io;
 233         struct list_head unwritten;
 234         unsigned long flags;
 235         struct ext4_inode_info *ei = EXT4_I(inode);
 236         int err, ret = 0;
 237
 238         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 239         dump_completed_IO(inode, head);
 240         list_replace_init(head, &unwritten);
 241         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 242
 243         while (!list_empty(&unwritten)) {
 244                 io = list_entry(unwritten.next, ext4_io_end_t, list);
 245                 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
 246                 list_del_init(&io->list);
 247
 248                 err = ext4_end_io(io);
 249                 if (unlikely(!ret && err))
 250                         ret = err;
 251         }
 252         return ret;
 253 }
 254
 255 /*
 256  * work on completed IO, to convert unwritten extents to extents
 257  */
 258 void ext4_end_io_rsv_work(struct work_struct *work)
 259 {
 260         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 261                                                   i_rsv_conversion_work);
 262         ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
 263 }
 264
 265 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 266 {
 267         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 268         if (io) {
 269                 atomic_inc(&EXT4_I(inode)->i_ioend_count);
 270                 io->inode = inode;
 271                 INIT_LIST_HEAD(&io->list);
 272                 atomic_set(&io->count, 1);
 273         }
 274         return io;
 275 }
 276
 277 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
 278 {
 279         if (atomic_dec_and_test(&io_end->count)) {
 280                 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
 281                         ext4_release_io_end(io_end);
 282                         return;
 283                 }
 284                 ext4_add_complete_io(io_end);
 285         }
 286 }
 287
 288 int ext4_put_io_end(ext4_io_end_t *io_end)
 289 {
 290         int err = 0;
 291
 292         if (atomic_dec_and_test(&io_end->count)) {
 293                 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 294                         err = ext4_convert_unwritten_extents(io_end->handle,
 295                                                 io_end->inode, io_end->offset,
 296                                                 io_end->size);
 297                         io_end->handle = NULL;
 298                         ext4_clear_io_unwritten_flag(io_end);
 299                 }
 300                 ext4_release_io_end(io_end);
 301         }
 302         return err;
 303 }
 304
 305 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
 306 {
 307         atomic_inc(&io_end->count);
 308         return io_end;
 309 }
 310
 311 /* BIO completion function for page writeback */
 312 static void ext4_end_bio(struct bio *bio)
 313 {
 314         ext4_io_end_t *io_end = bio->bi_private;
 315         sector_t bi_sector = bio->bi_iter.bi_sector;
 316
 317         BUG_ON(!io_end);
 318         bio->bi_end_io = NULL;
 319
 320         if (bio->bi_error) {
 321                 struct inode *inode = io_end->inode;
 322
 323                 ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
 324                              "(offset %llu size %ld starting block %llu)",
 325                              bio->bi_error, inode->i_ino,
 326                              (unsigned long long) io_end->offset,
 327                              (long) io_end->size,
 328                              (unsigned long long)
 329                              bi_sector >> (inode->i_blkbits - 9));
 330                 mapping_set_error(inode->i_mapping, bio->bi_error);
 331         }
 332
 333         if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 334                 /*
 335                  * Link bio into list hanging from io_end. We have to do it
 336                  * atomically as bio completions can be racing against each
 337                  * other.
 338                  */
 339                 bio->bi_private = xchg(&io_end->bio, bio);
 340                 ext4_put_io_end_defer(io_end);
 341         } else {
 342                 /*
 343                  * Drop io_end reference early. Inode can get freed once
 344                  * we finish the bio.
 345                  */
 346                 ext4_put_io_end_defer(io_end);
 347                 ext4_finish_bio(bio);
 348                 bio_put(bio);
 349         }
 350 }
 351
 352 void ext4_io_submit(struct ext4_io_submit *io)
 353 {
 354         struct bio *bio = io->io_bio;
 355
 356         if (bio) {
 357                 int io_op = io->io_wbc->sync_mode == WB_SYNC_ALL ?
 358                             WRITE_SYNC : WRITE;
 359                 bio_get(io->io_bio);
 360                 submit_bio(io_op, io->io_bio);
 361                 bio_put(io->io_bio);
 362         }
 363         io->io_bio = NULL;
 364 }
 365
 366 void ext4_io_submit_init(struct ext4_io_submit *io,
 367                          struct writeback_control *wbc)
 368 {
 369         io->io_wbc = wbc;
 370         io->io_bio = NULL;
 371         io->io_end = NULL;
 372 }
 373
 374 static int io_submit_init_bio(struct ext4_io_submit *io,
 375                               struct buffer_head *bh)
 376 {
 377         struct bio *bio;
 378
 379         bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
 380         if (!bio)
 381                 return -ENOMEM;
 382         wbc_init_bio(io->io_wbc, bio);
 383         bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 384         bio->bi_bdev = bh->b_bdev;
 385         bio->bi_end_io = ext4_end_bio;
 386         bio->bi_private = ext4_get_io_end(io->io_end);
 387         io->io_bio = bio;
 388         io->io_next_block = bh->b_blocknr;
 389         return 0;
 390 }
 391
 392 static int io_submit_add_bh(struct ext4_io_submit *io,
 393                             struct inode *inode,
 394                             struct page *page,
 395                             struct buffer_head *bh)
 396 {
 397         int ret;
 398
 399         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 400 submit_and_retry:
 401                 ext4_io_submit(io);
 402         }
 403         if (io->io_bio == NULL) {
 404                 ret = io_submit_init_bio(io, bh);
 405                 if (ret)
 406                         return ret;
 407         }
 408         ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
 409         if (ret != bh->b_size)
 410                 goto submit_and_retry;
 411         wbc_account_io(io->io_wbc, page, bh->b_size);
 412         io->io_next_block++;
 413         return 0;
 414 }
 415
 416 int ext4_bio_write_page(struct ext4_io_submit *io,
 417                         struct page *page,
 418                         int len,
 419                         struct writeback_control *wbc,
 420                         bool keep_towrite)
 421 {
 422         struct page *data_page = NULL;
 423         struct inode *inode = page->mapping->host;
 424         unsigned block_start, blocksize;
 425         struct buffer_head *bh, *head;
 426         int ret = 0;
 427         int nr_submitted = 0;
 428         int nr_to_submit = 0;
 429
 430         blocksize = 1 << inode->i_blkbits;
 431
 432         BUG_ON(!PageLocked(page));
 433         BUG_ON(PageWriteback(page));
 434
 435         if (keep_towrite)
 436                 set_page_writeback_keepwrite(page);
 437         else
 438                 set_page_writeback(page);
 439         ClearPageError(page);
 440
 441         /*
 442          * Comments copied from block_write_full_page:
 443          *
 444          * The page straddles i_size.  It must be zeroed out on each and every
 445          * writepage invocation because it may be mmapped.  "A file is mapped
 446          * in multiples of the page size.  For a file that is not a multiple of
 447          * the page size, the remaining memory is zeroed when mapped, and
 448          * writes to that region are not written out to the file."
 449          */
 450         if (len < PAGE_CACHE_SIZE)
 451                 zero_user_segment(page, len, PAGE_CACHE_SIZE);
 452         /*
 453          * In the first loop we prepare and mark buffers to submit. We have to
 454          * mark all buffers in the page before submitting so that
 455          * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
 456          * on the first buffer finishes and we are still working on submitting
 457          * the second buffer.
 458          */
 459         bh = head = page_buffers(page);
 460         do {
 461                 block_start = bh_offset(bh);
 462                 if (block_start >= len) {
 463                         clear_buffer_dirty(bh);
 464                         set_buffer_uptodate(bh);
 465                         continue;
 466                 }
 467                 if (!buffer_dirty(bh) || buffer_delay(bh) ||
 468                     !buffer_mapped(bh) || buffer_unwritten(bh)) {
 469                         /* A hole? We can safely clear the dirty bit */
 470                         if (!buffer_mapped(bh))
 471                                 clear_buffer_dirty(bh);
 472                         if (io->io_bio)
 473                                 ext4_io_submit(io);
 474                         continue;
 475                 }
 476                 if (buffer_new(bh)) {
 477                         clear_buffer_new(bh);
 478                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 479                 }
 480                 set_buffer_async_write(bh);
 481                 nr_to_submit++;
 482         } while ((bh = bh->b_this_page) != head);
 483
 484         bh = head = page_buffers(page);
 485
 486         if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
 487             nr_to_submit) {
 488                 data_page = ext4_encrypt(inode, page);
 489                 if (IS_ERR(data_page)) {
 490                         ret = PTR_ERR(data_page);
 491                         data_page = NULL;
 492                         goto out;
 493                 }
 494         }
 495
 496         /* Now submit buffers to write */
 497         do {
 498                 if (!buffer_async_write(bh))
 499                         continue;
 500                 ret = io_submit_add_bh(io, inode,
 501                                        data_page ? data_page : page, bh);
 502                 if (ret) {
 503                         /*
 504                          * We only get here on ENOMEM.  Not much else
 505                          * we can do but mark the page as dirty, and
 506                          * better luck next time.
 507                          */
 508                         break;
 509                 }
 510                 nr_submitted++;
 511                 clear_buffer_dirty(bh);
 512         } while ((bh = bh->b_this_page) != head);
 513
 514         /* Error stopped previous loop? Clean up buffers... */
 515         if (ret) {
 516         out:
 517                 if (data_page)
 518                         ext4_restore_control_page(data_page);
 519                 printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
 520                 redirty_page_for_writepage(wbc, page);
 521                 do {
 522                         clear_buffer_async_write(bh);
 523                         bh = bh->b_this_page;
 524                 } while (bh != head);
 525         }
 526         unlock_page(page);
 527         /* Nothing submitted - we have to end page writeback */
 528         if (!nr_submitted)
 529                 end_page_writeback(page);
 530         return ret;
 531 }