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/jbd2.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/aio.h>
  22 #include <linux/uio.h>
  23 #include <linux/bio.h>
  24 #include <linux/workqueue.h>
  25 #include <linux/kernel.h>
  26 #include <linux/slab.h>
  27 #include <linux/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
  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  * This function is called by ext4_evict_inode() to make sure there is
  50  * no more pending I/O completion work left to do.
  51  */
  52 void ext4_ioend_shutdown(struct inode *inode)
  53 {
  54         wait_queue_head_t *wq = ext4_ioend_wq(inode);
  55
  56         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
  57         /*
  58          * We need to make sure the work structure is finished being
  59          * used before we let the inode get destroyed.
  60          */
  61         if (work_pending(&EXT4_I(inode)->i_unwritten_work))
  62                 cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
  63 }
  64
  65 static void ext4_release_io_end(ext4_io_end_t *io_end)
  66 {
  67         BUG_ON(!list_empty(&io_end->list));
  68         BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
  69
  70         if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
  71                 wake_up_all(ext4_ioend_wq(io_end->inode));
  72         if (io_end->flag & EXT4_IO_END_DIRECT)
  73                 inode_dio_done(io_end->inode);
  74         if (io_end->iocb)
  75                 aio_complete(io_end->iocb, io_end->result, 0);
  76         kmem_cache_free(io_end_cachep, io_end);
  77 }
  78
  79 static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
  80 {
  81         struct inode *inode = io_end->inode;
  82
  83         io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
  84         /* Wake up anyone waiting on unwritten extent conversion */
  85         if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
  86                 wake_up_all(ext4_ioend_wq(inode));
  87 }
  88
  89 /* check a range of space and convert unwritten extents to written. */
  90 static int ext4_end_io(ext4_io_end_t *io)
  91 {
  92         struct inode *inode = io->inode;
  93         loff_t offset = io->offset;
  94         ssize_t size = io->size;
  95         int ret = 0;
  96
  97         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
  98                    "list->prev 0x%p\n",
  99                    io, inode->i_ino, io->list.next, io->list.prev);
 100
 101         ret = ext4_convert_unwritten_extents(inode, offset, size);
 102         if (ret < 0) {
 103                 ext4_msg(inode->i_sb, KERN_EMERG,
 104                          "failed to convert unwritten extents to written "
 105                          "extents -- potential data loss!  "
 106                          "(inode %lu, offset %llu, size %zd, error %d)",
 107                          inode->i_ino, offset, size, ret);
 108         }
 109         ext4_clear_io_unwritten_flag(io);
 110         ext4_release_io_end(io);
 111         return ret;
 112 }
 113
 114 static void dump_completed_IO(struct inode *inode)
 115 {
 116 #ifdef  EXT4FS_DEBUG
 117         struct list_head *cur, *before, *after;
 118         ext4_io_end_t *io, *io0, *io1;
 119
 120         if (list_empty(&EXT4_I(inode)->i_completed_io_list)) {
 121                 ext4_debug("inode %lu completed_io list is empty\n",
 122                            inode->i_ino);
 123                 return;
 124         }
 125
 126         ext4_debug("Dump inode %lu completed_io list\n", inode->i_ino);
 127         list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list) {
 128                 cur = &io->list;
 129                 before = cur->prev;
 130                 io0 = container_of(before, ext4_io_end_t, list);
 131                 after = cur->next;
 132                 io1 = container_of(after, ext4_io_end_t, list);
 133
 134                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 135                             io, inode->i_ino, io0, io1);
 136         }
 137 #endif
 138 }
 139
 140 /* Add the io_end to per-inode completed end_io list. */
 141 static void ext4_add_complete_io(ext4_io_end_t *io_end)
 142 {
 143         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 144         struct workqueue_struct *wq;
 145         unsigned long flags;
 146
 147         BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 148         wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
 149
 150         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 151         if (list_empty(&ei->i_completed_io_list))
 152                 queue_work(wq, &ei->i_unwritten_work);
 153         list_add_tail(&io_end->list, &ei->i_completed_io_list);
 154         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 155 }
 156
 157 static int ext4_do_flush_completed_IO(struct inode *inode)
 158 {
 159         ext4_io_end_t *io;
 160         struct list_head unwritten;
 161         unsigned long flags;
 162         struct ext4_inode_info *ei = EXT4_I(inode);
 163         int err, ret = 0;
 164
 165         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 166         dump_completed_IO(inode);
 167         list_replace_init(&ei->i_completed_io_list, &unwritten);
 168         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 169
 170         while (!list_empty(&unwritten)) {
 171                 io = list_entry(unwritten.next, ext4_io_end_t, list);
 172                 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
 173                 list_del_init(&io->list);
 174
 175                 err = ext4_end_io(io);
 176                 if (unlikely(!ret && err))
 177                         ret = err;
 178         }
 179         return ret;
 180 }
 181
 182 /*
 183  * work on completed aio dio IO, to convert unwritten extents to extents
 184  */
 185 void ext4_end_io_work(struct work_struct *work)
 186 {
 187         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 188                                                   i_unwritten_work);
 189         ext4_do_flush_completed_IO(&ei->vfs_inode);
 190 }
 191
 192 int ext4_flush_unwritten_io(struct inode *inode)
 193 {
 194         int ret;
 195         WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) &&
 196                      !(inode->i_state & I_FREEING));
 197         ret = ext4_do_flush_completed_IO(inode);
 198         ext4_unwritten_wait(inode);
 199         return ret;
 200 }
 201
 202 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 203 {
 204         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 205         if (io) {
 206                 atomic_inc(&EXT4_I(inode)->i_ioend_count);
 207                 io->inode = inode;
 208                 INIT_LIST_HEAD(&io->list);
 209                 atomic_set(&io->count, 1);
 210         }
 211         return io;
 212 }
 213
 214 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
 215 {
 216         if (atomic_dec_and_test(&io_end->count)) {
 217                 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
 218                         ext4_release_io_end(io_end);
 219                         return;
 220                 }
 221                 ext4_add_complete_io(io_end);
 222         }
 223 }
 224
 225 int ext4_put_io_end(ext4_io_end_t *io_end)
 226 {
 227         int err = 0;
 228
 229         if (atomic_dec_and_test(&io_end->count)) {
 230                 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
 231                         err = ext4_convert_unwritten_extents(io_end->inode,
 232                                                 io_end->offset, io_end->size);
 233                         ext4_clear_io_unwritten_flag(io_end);
 234                 }
 235                 ext4_release_io_end(io_end);
 236         }
 237         return err;
 238 }
 239
 240 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
 241 {
 242         atomic_inc(&io_end->count);
 243         return io_end;
 244 }
 245
 246 /*
 247  * Print an buffer I/O error compatible with the fs/buffer.c.  This
 248  * provides compatibility with dmesg scrapers that look for a specific
 249  * buffer I/O error message.  We really need a unified error reporting
 250  * structure to userspace ala Digital Unix's uerf system, but it's
 251  * probably not going to happen in my lifetime, due to LKML politics...
 252  */
 253 static void buffer_io_error(struct buffer_head *bh)
 254 {
 255         char b[BDEVNAME_SIZE];
 256         printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
 257                         bdevname(bh->b_bdev, b),
 258                         (unsigned long long)bh->b_blocknr);
 259 }
 260
 261 static void ext4_end_bio(struct bio *bio, int error)
 262 {
 263         ext4_io_end_t *io_end = bio->bi_private;
 264         struct inode *inode;
 265         int i;
 266         int blocksize;
 267         sector_t bi_sector = bio->bi_sector;
 268
 269         BUG_ON(!io_end);
 270         inode = io_end->inode;
 271         blocksize = 1 << inode->i_blkbits;
 272         bio->bi_private = NULL;
 273         bio->bi_end_io = NULL;
 274         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
 275                 error = 0;
 276         for (i = 0; i < bio->bi_vcnt; i++) {
 277                 struct bio_vec *bvec = &bio->bi_io_vec[i];
 278                 struct page *page = bvec->bv_page;
 279                 struct buffer_head *bh, *head;
 280                 unsigned bio_start = bvec->bv_offset;
 281                 unsigned bio_end = bio_start + bvec->bv_len;
 282                 unsigned under_io = 0;
 283                 unsigned long flags;
 284
 285                 if (!page)
 286                         continue;
 287
 288                 if (error) {
 289                         SetPageError(page);
 290                         set_bit(AS_EIO, &page->mapping->flags);
 291                 }
 292                 bh = head = page_buffers(page);
 293                 /*
 294                  * We check all buffers in the page under BH_Uptodate_Lock
 295                  * to avoid races with other end io clearing async_write flags
 296                  */
 297                 local_irq_save(flags);
 298                 bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
 299                 do {
 300                         if (bh_offset(bh) < bio_start ||
 301                             bh_offset(bh) + blocksize > bio_end) {
 302                                 if (buffer_async_write(bh))
 303                                         under_io++;
 304                                 continue;
 305                         }
 306                         clear_buffer_async_write(bh);
 307                         if (error)
 308                                 buffer_io_error(bh);
 309                 } while ((bh = bh->b_this_page) != head);
 310                 bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
 311                 local_irq_restore(flags);
 312                 if (!under_io)
 313                         end_page_writeback(page);
 314         }
 315         bio_put(bio);
 316
 317         if (error) {
 318                 io_end->flag |= EXT4_IO_END_ERROR;
 319                 ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
 320                              "(offset %llu size %ld starting block %llu)",
 321                              inode->i_ino,
 322                              (unsigned long long) io_end->offset,
 323                              (long) io_end->size,
 324                              (unsigned long long)
 325                              bi_sector >> (inode->i_blkbits - 9));
 326         }
 327
 328         ext4_put_io_end_defer(io_end);
 329 }
 330
 331 void ext4_io_submit(struct ext4_io_submit *io)
 332 {
 333         struct bio *bio = io->io_bio;
 334
 335         if (bio) {
 336                 bio_get(io->io_bio);
 337                 submit_bio(io->io_op, io->io_bio);
 338                 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
 339                 bio_put(io->io_bio);
 340         }
 341         io->io_bio = NULL;
 342 }
 343
 344 void ext4_io_submit_init(struct ext4_io_submit *io,
 345                          struct writeback_control *wbc)
 346 {
 347         io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
 348         io->io_bio = NULL;
 349         io->io_end = NULL;
 350 }
 351
 352 static int io_submit_init_bio(struct ext4_io_submit *io,
 353                               struct buffer_head *bh)
 354 {
 355         int nvecs = bio_get_nr_vecs(bh->b_bdev);
 356         struct bio *bio;
 357
 358         bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
 359         bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 360         bio->bi_bdev = bh->b_bdev;
 361         bio->bi_end_io = ext4_end_bio;
 362         bio->bi_private = ext4_get_io_end(io->io_end);
 363         if (!io->io_end->size)
 364                 io->io_end->offset = (bh->b_page->index << PAGE_CACHE_SHIFT)
 365                                      + bh_offset(bh);
 366         io->io_bio = bio;
 367         io->io_next_block = bh->b_blocknr;
 368         return 0;
 369 }
 370
 371 static int io_submit_add_bh(struct ext4_io_submit *io,
 372                             struct inode *inode,
 373                             struct buffer_head *bh)
 374 {
 375         ext4_io_end_t *io_end;
 376         int ret;
 377
 378         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 379 submit_and_retry:
 380                 ext4_io_submit(io);
 381         }
 382         if (io->io_bio == NULL) {
 383                 ret = io_submit_init_bio(io, bh);
 384                 if (ret)
 385                         return ret;
 386         }
 387         ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
 388         if (ret != bh->b_size)
 389                 goto submit_and_retry;
 390         io_end = io->io_end;
 391         if (test_clear_buffer_uninit(bh))
 392                 ext4_set_io_unwritten_flag(inode, io_end);
 393         io_end->size += bh->b_size;
 394         io->io_next_block++;
 395         return 0;
 396 }
 397
 398 int ext4_bio_write_page(struct ext4_io_submit *io,
 399                         struct page *page,
 400                         int len,
 401                         struct writeback_control *wbc)
 402 {
 403         struct inode *inode = page->mapping->host;
 404         unsigned block_start, blocksize;
 405         struct buffer_head *bh, *head;
 406         int ret = 0;
 407         int nr_submitted = 0;
 408
 409         blocksize = 1 << inode->i_blkbits;
 410
 411         BUG_ON(!PageLocked(page));
 412         BUG_ON(PageWriteback(page));
 413
 414         set_page_writeback(page);
 415         ClearPageError(page);
 416
 417         /*
 418          * In the first loop we prepare and mark buffers to submit. We have to
 419          * mark all buffers in the page before submitting so that
 420          * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
 421          * on the first buffer finishes and we are still working on submitting
 422          * the second buffer.
 423          */
 424         bh = head = page_buffers(page);
 425         do {
 426                 block_start = bh_offset(bh);
 427                 if (block_start >= len) {
 428                         /*
 429                          * Comments copied from block_write_full_page_endio:
 430                          *
 431                          * The page straddles i_size.  It must be zeroed out on
 432                          * each and every writepage invocation because it may
 433                          * be mmapped.  "A file is mapped in multiples of the
 434                          * page size.  For a file that is not a multiple of
 435                          * the  page size, the remaining memory is zeroed when
 436                          * mapped, and writes to that region are not written
 437                          * out to the file."
 438                          */
 439                         zero_user_segment(page, block_start,
 440                                           block_start + blocksize);
 441                         clear_buffer_dirty(bh);
 442                         set_buffer_uptodate(bh);
 443                         continue;
 444                 }
 445                 if (!buffer_dirty(bh) || buffer_delay(bh) ||
 446                     !buffer_mapped(bh) || buffer_unwritten(bh)) {
 447                         /* A hole? We can safely clear the dirty bit */
 448                         if (!buffer_mapped(bh))
 449                                 clear_buffer_dirty(bh);
 450                         if (io->io_bio)
 451                                 ext4_io_submit(io);
 452                         continue;
 453                 }
 454                 if (buffer_new(bh)) {
 455                         clear_buffer_new(bh);
 456                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 457                 }
 458                 set_buffer_async_write(bh);
 459         } while ((bh = bh->b_this_page) != head);
 460
 461         /* Now submit buffers to write */
 462         bh = head = page_buffers(page);
 463         do {
 464                 if (!buffer_async_write(bh))
 465                         continue;
 466                 ret = io_submit_add_bh(io, inode, bh);
 467                 if (ret) {
 468                         /*
 469                          * We only get here on ENOMEM.  Not much else
 470                          * we can do but mark the page as dirty, and
 471                          * better luck next time.
 472                          */
 473                         redirty_page_for_writepage(wbc, page);
 474                         break;
 475                 }
 476                 nr_submitted++;
 477                 clear_buffer_dirty(bh);
 478         } while ((bh = bh->b_this_page) != head);
 479
 480         /* Error stopped previous loop? Clean up buffers... */
 481         if (ret) {
 482                 do {
 483                         clear_buffer_async_write(bh);
 484                         bh = bh->b_this_page;
 485                 } while (bh != head);
 486         }
 487         unlock_page(page);
 488         /* Nothing submitted - we have to end page writeback */
 489         if (!nr_submitted)
 490                 end_page_writeback(page);
 491         return ret;
 492 }