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 void ext4_free_io_end(ext4_io_end_t *io)
  66 {
  67         BUG_ON(!io);
  68         BUG_ON(!list_empty(&io->list));
  69         BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
  70
  71         if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
  72                 wake_up_all(ext4_ioend_wq(io->inode));
  73         kmem_cache_free(io_end_cachep, io);
  74 }
  75
  76 /* check a range of space and convert unwritten extents to written. */
  77 static int ext4_end_io(ext4_io_end_t *io)
  78 {
  79         struct inode *inode = io->inode;
  80         loff_t offset = io->offset;
  81         ssize_t size = io->size;
  82         int ret = 0;
  83
  84         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
  85                    "list->prev 0x%p\n",
  86                    io, inode->i_ino, io->list.next, io->list.prev);
  87
  88         ret = ext4_convert_unwritten_extents(inode, offset, size);
  89         if (ret < 0) {
  90                 ext4_msg(inode->i_sb, KERN_EMERG,
  91                          "failed to convert unwritten extents to written "
  92                          "extents -- potential data loss!  "
  93                          "(inode %lu, offset %llu, size %zd, error %d)",
  94                          inode->i_ino, offset, size, ret);
  95         }
  96         /* Wake up anyone waiting on unwritten extent conversion */
  97         if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
  98                 wake_up_all(ext4_ioend_wq(inode));
  99         if (io->flag & EXT4_IO_END_DIRECT)
 100                 inode_dio_done(inode);
 101         if (io->iocb)
 102                 aio_complete(io->iocb, io->result, 0);
 103         return ret;
 104 }
 105
 106 static void dump_completed_IO(struct inode *inode)
 107 {
 108 #ifdef  EXT4FS_DEBUG
 109         struct list_head *cur, *before, *after;
 110         ext4_io_end_t *io, *io0, *io1;
 111
 112         if (list_empty(&EXT4_I(inode)->i_completed_io_list)) {
 113                 ext4_debug("inode %lu completed_io list is empty\n",
 114                            inode->i_ino);
 115                 return;
 116         }
 117
 118         ext4_debug("Dump inode %lu completed_io list\n", inode->i_ino);
 119         list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list) {
 120                 cur = &io->list;
 121                 before = cur->prev;
 122                 io0 = container_of(before, ext4_io_end_t, list);
 123                 after = cur->next;
 124                 io1 = container_of(after, ext4_io_end_t, list);
 125
 126                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 127                             io, inode->i_ino, io0, io1);
 128         }
 129 #endif
 130 }
 131
 132 /* Add the io_end to per-inode completed end_io list. */
 133 void ext4_add_complete_io(ext4_io_end_t *io_end)
 134 {
 135         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 136         struct workqueue_struct *wq;
 137         unsigned long flags;
 138
 139         BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 140         wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
 141
 142         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 143         if (list_empty(&ei->i_completed_io_list))
 144                 queue_work(wq, &ei->i_unwritten_work);
 145         list_add_tail(&io_end->list, &ei->i_completed_io_list);
 146         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 147 }
 148
 149 static int ext4_do_flush_completed_IO(struct inode *inode)
 150 {
 151         ext4_io_end_t *io;
 152         struct list_head unwritten;
 153         unsigned long flags;
 154         struct ext4_inode_info *ei = EXT4_I(inode);
 155         int err, ret = 0;
 156
 157         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 158         dump_completed_IO(inode);
 159         list_replace_init(&ei->i_completed_io_list, &unwritten);
 160         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 161
 162         while (!list_empty(&unwritten)) {
 163                 io = list_entry(unwritten.next, ext4_io_end_t, list);
 164                 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
 165                 list_del_init(&io->list);
 166
 167                 err = ext4_end_io(io);
 168                 if (unlikely(!ret && err))
 169                         ret = err;
 170                 io->flag &= ~EXT4_IO_END_UNWRITTEN;
 171                 ext4_free_io_end(io);
 172         }
 173         return ret;
 174 }
 175
 176 /*
 177  * work on completed aio dio IO, to convert unwritten extents to extents
 178  */
 179 void ext4_end_io_work(struct work_struct *work)
 180 {
 181         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 182                                                   i_unwritten_work);
 183         ext4_do_flush_completed_IO(&ei->vfs_inode);
 184 }
 185
 186 int ext4_flush_unwritten_io(struct inode *inode)
 187 {
 188         int ret;
 189         WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) &&
 190                      !(inode->i_state & I_FREEING));
 191         ret = ext4_do_flush_completed_IO(inode);
 192         ext4_unwritten_wait(inode);
 193         return ret;
 194 }
 195
 196 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 197 {
 198         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 199         if (io) {
 200                 atomic_inc(&EXT4_I(inode)->i_ioend_count);
 201                 io->inode = inode;
 202                 INIT_LIST_HEAD(&io->list);
 203         }
 204         return io;
 205 }
 206
 207 /*
 208  * Print an buffer I/O error compatible with the fs/buffer.c.  This
 209  * provides compatibility with dmesg scrapers that look for a specific
 210  * buffer I/O error message.  We really need a unified error reporting
 211  * structure to userspace ala Digital Unix's uerf system, but it's
 212  * probably not going to happen in my lifetime, due to LKML politics...
 213  */
 214 static void buffer_io_error(struct buffer_head *bh)
 215 {
 216         char b[BDEVNAME_SIZE];
 217         printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
 218                         bdevname(bh->b_bdev, b),
 219                         (unsigned long long)bh->b_blocknr);
 220 }
 221
 222 static void ext4_end_bio(struct bio *bio, int error)
 223 {
 224         ext4_io_end_t *io_end = bio->bi_private;
 225         struct inode *inode;
 226         int i;
 227         int blocksize;
 228         sector_t bi_sector = bio->bi_sector;
 229
 230         BUG_ON(!io_end);
 231         inode = io_end->inode;
 232         blocksize = 1 << inode->i_blkbits;
 233         bio->bi_private = NULL;
 234         bio->bi_end_io = NULL;
 235         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
 236                 error = 0;
 237         for (i = 0; i < bio->bi_vcnt; i++) {
 238                 struct bio_vec *bvec = &bio->bi_io_vec[i];
 239                 struct page *page = bvec->bv_page;
 240                 struct buffer_head *bh, *head;
 241                 unsigned bio_start = bvec->bv_offset;
 242                 unsigned bio_end = bio_start + bvec->bv_len;
 243                 unsigned under_io = 0;
 244                 unsigned long flags;
 245
 246                 if (!page)
 247                         continue;
 248
 249                 if (error) {
 250                         SetPageError(page);
 251                         set_bit(AS_EIO, &page->mapping->flags);
 252                 }
 253                 bh = head = page_buffers(page);
 254                 /*
 255                  * We check all buffers in the page under BH_Uptodate_Lock
 256                  * to avoid races with other end io clearing async_write flags
 257                  */
 258                 local_irq_save(flags);
 259                 bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
 260                 do {
 261                         if (bh_offset(bh) < bio_start ||
 262                             bh_offset(bh) + blocksize > bio_end) {
 263                                 if (buffer_async_write(bh))
 264                                         under_io++;
 265                                 continue;
 266                         }
 267                         clear_buffer_async_write(bh);
 268                         if (error)
 269                                 buffer_io_error(bh);
 270                 } while ((bh = bh->b_this_page) != head);
 271                 bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
 272                 local_irq_restore(flags);
 273                 if (!under_io)
 274                         end_page_writeback(page);
 275         }
 276         bio_put(bio);
 277
 278         if (error) {
 279                 io_end->flag |= EXT4_IO_END_ERROR;
 280                 ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
 281                              "(offset %llu size %ld starting block %llu)",
 282                              inode->i_ino,
 283                              (unsigned long long) io_end->offset,
 284                              (long) io_end->size,
 285                              (unsigned long long)
 286                              bi_sector >> (inode->i_blkbits - 9));
 287         }
 288
 289         if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
 290                 ext4_free_io_end(io_end);
 291                 return;
 292         }
 293
 294         ext4_add_complete_io(io_end);
 295 }
 296
 297 void ext4_io_submit(struct ext4_io_submit *io)
 298 {
 299         struct bio *bio = io->io_bio;
 300
 301         if (bio) {
 302                 bio_get(io->io_bio);
 303                 submit_bio(io->io_op, io->io_bio);
 304                 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
 305                 bio_put(io->io_bio);
 306         }
 307         io->io_bio = NULL;
 308         io->io_op = 0;
 309         io->io_end = NULL;
 310 }
 311
 312 static int io_submit_init(struct ext4_io_submit *io,
 313                           struct inode *inode,
 314                           struct writeback_control *wbc,
 315                           struct buffer_head *bh)
 316 {
 317         ext4_io_end_t *io_end;
 318         struct page *page = bh->b_page;
 319         int nvecs = bio_get_nr_vecs(bh->b_bdev);
 320         struct bio *bio;
 321
 322         io_end = ext4_init_io_end(inode, GFP_NOFS);
 323         if (!io_end)
 324                 return -ENOMEM;
 325         bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
 326         bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 327         bio->bi_bdev = bh->b_bdev;
 328         bio->bi_private = io->io_end = io_end;
 329         bio->bi_end_io = ext4_end_bio;
 330
 331         io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
 332
 333         io->io_bio = bio;
 334         io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
 335         io->io_next_block = bh->b_blocknr;
 336         return 0;
 337 }
 338
 339 static int io_submit_add_bh(struct ext4_io_submit *io,
 340                             struct inode *inode,
 341                             struct writeback_control *wbc,
 342                             struct buffer_head *bh)
 343 {
 344         ext4_io_end_t *io_end;
 345         int ret;
 346
 347         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 348 submit_and_retry:
 349                 ext4_io_submit(io);
 350         }
 351         if (io->io_bio == NULL) {
 352                 ret = io_submit_init(io, inode, wbc, bh);
 353                 if (ret)
 354                         return ret;
 355         }
 356         io_end = io->io_end;
 357         if (test_clear_buffer_uninit(bh))
 358                 ext4_set_io_unwritten_flag(inode, io_end);
 359         io->io_end->size += bh->b_size;
 360         io->io_next_block++;
 361         ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
 362         if (ret != bh->b_size)
 363                 goto submit_and_retry;
 364         return 0;
 365 }
 366
 367 int ext4_bio_write_page(struct ext4_io_submit *io,
 368                         struct page *page,
 369                         int len,
 370                         struct writeback_control *wbc)
 371 {
 372         struct inode *inode = page->mapping->host;
 373         unsigned block_start, blocksize;
 374         struct buffer_head *bh, *head;
 375         int ret = 0;
 376         int nr_submitted = 0;
 377
 378         blocksize = 1 << inode->i_blkbits;
 379
 380         BUG_ON(!PageLocked(page));
 381         BUG_ON(PageWriteback(page));
 382
 383         set_page_writeback(page);
 384         ClearPageError(page);
 385
 386         /*
 387          * In the first loop we prepare and mark buffers to submit. We have to
 388          * mark all buffers in the page before submitting so that
 389          * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
 390          * on the first buffer finishes and we are still working on submitting
 391          * the second buffer.
 392          */
 393         bh = head = page_buffers(page);
 394         do {
 395                 block_start = bh_offset(bh);
 396                 if (block_start >= len) {
 397                         /*
 398                          * Comments copied from block_write_full_page_endio:
 399                          *
 400                          * The page straddles i_size.  It must be zeroed out on
 401                          * each and every writepage invocation because it may
 402                          * be mmapped.  "A file is mapped in multiples of the
 403                          * page size.  For a file that is not a multiple of
 404                          * the  page size, the remaining memory is zeroed when
 405                          * mapped, and writes to that region are not written
 406                          * out to the file."
 407                          */
 408                         zero_user_segment(page, block_start,
 409                                           block_start + blocksize);
 410                         clear_buffer_dirty(bh);
 411                         set_buffer_uptodate(bh);
 412                         continue;
 413                 }
 414                 if (!buffer_dirty(bh) || buffer_delay(bh) ||
 415                     !buffer_mapped(bh) || buffer_unwritten(bh)) {
 416                         /* A hole? We can safely clear the dirty bit */
 417                         if (!buffer_mapped(bh))
 418                                 clear_buffer_dirty(bh);
 419                         if (io->io_bio)
 420                                 ext4_io_submit(io);
 421                         continue;
 422                 }
 423                 if (buffer_new(bh)) {
 424                         clear_buffer_new(bh);
 425                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 426                 }
 427                 set_buffer_async_write(bh);
 428         } while ((bh = bh->b_this_page) != head);
 429
 430         /* Now submit buffers to write */
 431         bh = head = page_buffers(page);
 432         do {
 433                 if (!buffer_async_write(bh))
 434                         continue;
 435                 ret = io_submit_add_bh(io, inode, wbc, bh);
 436                 if (ret) {
 437                         /*
 438                          * We only get here on ENOMEM.  Not much else
 439                          * we can do but mark the page as dirty, and
 440                          * better luck next time.
 441                          */
 442                         redirty_page_for_writepage(wbc, page);
 443                         break;
 444                 }
 445                 nr_submitted++;
 446                 clear_buffer_dirty(bh);
 447         } while ((bh = bh->b_this_page) != head);
 448
 449         /* Error stopped previous loop? Clean up buffers... */
 450         if (ret) {
 451                 do {
 452                         clear_buffer_async_write(bh);
 453                         bh = bh->b_this_page;
 454                 } while (bh != head);
 455         }
 456         unlock_page(page);
 457         /* Nothing submitted - we have to end page writeback */
 458         if (!nr_submitted)
 459                 end_page_writeback(page);
 460         return ret;
 461 }