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/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
  28 #include "ext4_jbd2.h"
  29 #include "xattr.h"
  30 #include "acl.h"
  31
  32 static struct kmem_cache *io_page_cachep, *io_end_cachep;
  33
  34 int __init ext4_init_pageio(void)
  35 {
  36         io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
  37         if (io_page_cachep == NULL)
  38                 return -ENOMEM;
  39         io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
  40         if (io_end_cachep == NULL) {
  41                 kmem_cache_destroy(io_page_cachep);
  42                 return -ENOMEM;
  43         }
  44         return 0;
  45 }
  46
  47 void ext4_exit_pageio(void)
  48 {
  49         kmem_cache_destroy(io_end_cachep);
  50         kmem_cache_destroy(io_page_cachep);
  51 }
  52
  53 /*
  54  * This function is called by ext4_evict_inode() to make sure there is
  55  * no more pending I/O completion work left to do.
  56  */
  57 void ext4_ioend_shutdown(struct inode *inode)
  58 {
  59         wait_queue_head_t *wq = ext4_ioend_wq(inode);
  60
  61         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
  62         /*
  63          * We need to make sure the work structure is finished being
  64          * used before we let the inode get destroyed.
  65          */
  66         if (work_pending(&EXT4_I(inode)->i_unwritten_work))
  67                 cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
  68 }
  69
  70 static void put_io_page(struct ext4_io_page *io_page)
  71 {
  72         if (atomic_dec_and_test(&io_page->p_count)) {
  73                 end_page_writeback(io_page->p_page);
  74                 put_page(io_page->p_page);
  75                 kmem_cache_free(io_page_cachep, io_page);
  76         }
  77 }
  78
  79 void ext4_free_io_end(ext4_io_end_t *io)
  80 {
  81         int i;
  82
  83         BUG_ON(!io);
  84         BUG_ON(!list_empty(&io->list));
  85         BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
  86
  87         for (i = 0; i < io->num_io_pages; i++)
  88                 put_io_page(io->pages[i]);
  89         io->num_io_pages = 0;
  90         if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
  91                 wake_up_all(ext4_ioend_wq(io->inode));
  92         kmem_cache_free(io_end_cachep, io);
  93 }
  94
  95 /* check a range of space and convert unwritten extents to written. */
  96 static int ext4_end_io(ext4_io_end_t *io)
  97 {
  98         struct inode *inode = io->inode;
  99         loff_t offset = io->offset;
 100         ssize_t size = io->size;
 101         int ret = 0;
 102
 103         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
 104                    "list->prev 0x%p\n",
 105                    io, inode->i_ino, io->list.next, io->list.prev);
 106
 107         ret = ext4_convert_unwritten_extents(inode, offset, size);
 108         if (ret < 0) {
 109                 ext4_msg(inode->i_sb, KERN_EMERG,
 110                          "failed to convert unwritten extents to written "
 111                          "extents -- potential data loss!  "
 112                          "(inode %lu, offset %llu, size %zd, error %d)",
 113                          inode->i_ino, offset, size, ret);
 114         }
 115         /* Wake up anyone waiting on unwritten extent conversion */
 116         if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
 117                 wake_up_all(ext4_ioend_wq(inode));
 118         if (io->flag & EXT4_IO_END_DIRECT)
 119                 inode_dio_done(inode);
 120         if (io->iocb)
 121                 aio_complete(io->iocb, io->result, 0);
 122         return ret;
 123 }
 124
 125 static void dump_completed_IO(struct inode *inode)
 126 {
 127 #ifdef  EXT4FS_DEBUG
 128         struct list_head *cur, *before, *after;
 129         ext4_io_end_t *io, *io0, *io1;
 130
 131         if (list_empty(&EXT4_I(inode)->i_completed_io_list)) {
 132                 ext4_debug("inode %lu completed_io list is empty\n",
 133                            inode->i_ino);
 134                 return;
 135         }
 136
 137         ext4_debug("Dump inode %lu completed_io list\n", inode->i_ino);
 138         list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list) {
 139                 cur = &io->list;
 140                 before = cur->prev;
 141                 io0 = container_of(before, ext4_io_end_t, list);
 142                 after = cur->next;
 143                 io1 = container_of(after, ext4_io_end_t, list);
 144
 145                 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
 146                             io, inode->i_ino, io0, io1);
 147         }
 148 #endif
 149 }
 150
 151 /* Add the io_end to per-inode completed end_io list. */
 152 void ext4_add_complete_io(ext4_io_end_t *io_end)
 153 {
 154         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 155         struct workqueue_struct *wq;
 156         unsigned long flags;
 157
 158         BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
 159         wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
 160
 161         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 162         if (list_empty(&ei->i_completed_io_list))
 163                 queue_work(wq, &ei->i_unwritten_work);
 164         list_add_tail(&io_end->list, &ei->i_completed_io_list);
 165         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 166 }
 167
 168 static int ext4_do_flush_completed_IO(struct inode *inode)
 169 {
 170         ext4_io_end_t *io;
 171         struct list_head unwritten;
 172         unsigned long flags;
 173         struct ext4_inode_info *ei = EXT4_I(inode);
 174         int err, ret = 0;
 175
 176         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 177         dump_completed_IO(inode);
 178         list_replace_init(&ei->i_completed_io_list, &unwritten);
 179         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 180
 181         while (!list_empty(&unwritten)) {
 182                 io = list_entry(unwritten.next, ext4_io_end_t, list);
 183                 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
 184                 list_del_init(&io->list);
 185
 186                 err = ext4_end_io(io);
 187                 if (unlikely(!ret && err))
 188                         ret = err;
 189                 io->flag &= ~EXT4_IO_END_UNWRITTEN;
 190                 ext4_free_io_end(io);
 191         }
 192         return ret;
 193 }
 194
 195 /*
 196  * work on completed aio dio IO, to convert unwritten extents to extents
 197  */
 198 void ext4_end_io_work(struct work_struct *work)
 199 {
 200         struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
 201                                                   i_unwritten_work);
 202         ext4_do_flush_completed_IO(&ei->vfs_inode);
 203 }
 204
 205 int ext4_flush_unwritten_io(struct inode *inode)
 206 {
 207         int ret;
 208         WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) &&
 209                      !(inode->i_state & I_FREEING));
 210         ret = ext4_do_flush_completed_IO(inode);
 211         ext4_unwritten_wait(inode);
 212         return ret;
 213 }
 214
 215 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 216 {
 217         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 218         if (io) {
 219                 atomic_inc(&EXT4_I(inode)->i_ioend_count);
 220                 io->inode = inode;
 221                 INIT_LIST_HEAD(&io->list);
 222         }
 223         return io;
 224 }
 225
 226 /*
 227  * Print an buffer I/O error compatible with the fs/buffer.c.  This
 228  * provides compatibility with dmesg scrapers that look for a specific
 229  * buffer I/O error message.  We really need a unified error reporting
 230  * structure to userspace ala Digital Unix's uerf system, but it's
 231  * probably not going to happen in my lifetime, due to LKML politics...
 232  */
 233 static void buffer_io_error(struct buffer_head *bh)
 234 {
 235         char b[BDEVNAME_SIZE];
 236         printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
 237                         bdevname(bh->b_bdev, b),
 238                         (unsigned long long)bh->b_blocknr);
 239 }
 240
 241 static void ext4_end_bio(struct bio *bio, int error)
 242 {
 243         ext4_io_end_t *io_end = bio->bi_private;
 244         struct inode *inode;
 245         int i;
 246         sector_t bi_sector = bio->bi_sector;
 247
 248         BUG_ON(!io_end);
 249         bio->bi_private = NULL;
 250         bio->bi_end_io = NULL;
 251         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
 252                 error = 0;
 253         bio_put(bio);
 254
 255         for (i = 0; i < io_end->num_io_pages; i++) {
 256                 struct page *page = io_end->pages[i]->p_page;
 257                 struct buffer_head *bh, *head;
 258                 loff_t offset;
 259                 loff_t io_end_offset;
 260
 261                 if (error) {
 262                         SetPageError(page);
 263                         set_bit(AS_EIO, &page->mapping->flags);
 264                         head = page_buffers(page);
 265                         BUG_ON(!head);
 266
 267                         io_end_offset = io_end->offset + io_end->size;
 268
 269                         offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
 270                         bh = head;
 271                         do {
 272                                 if ((offset >= io_end->offset) &&
 273                                     (offset+bh->b_size <= io_end_offset))
 274                                         buffer_io_error(bh);
 275
 276                                 offset += bh->b_size;
 277                                 bh = bh->b_this_page;
 278                         } while (bh != head);
 279                 }
 280
 281                 put_io_page(io_end->pages[i]);
 282         }
 283         io_end->num_io_pages = 0;
 284         inode = io_end->inode;
 285
 286         if (error) {
 287                 io_end->flag |= EXT4_IO_END_ERROR;
 288                 ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
 289                              "(offset %llu size %ld starting block %llu)",
 290                              inode->i_ino,
 291                              (unsigned long long) io_end->offset,
 292                              (long) io_end->size,
 293                              (unsigned long long)
 294                              bi_sector >> (inode->i_blkbits - 9));
 295         }
 296
 297         if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
 298                 ext4_free_io_end(io_end);
 299                 return;
 300         }
 301
 302         ext4_add_complete_io(io_end);
 303 }
 304
 305 void ext4_io_submit(struct ext4_io_submit *io)
 306 {
 307         struct bio *bio = io->io_bio;
 308
 309         if (bio) {
 310                 bio_get(io->io_bio);
 311                 submit_bio(io->io_op, io->io_bio);
 312                 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
 313                 bio_put(io->io_bio);
 314         }
 315         io->io_bio = NULL;
 316         io->io_op = 0;
 317         io->io_end = NULL;
 318 }
 319
 320 static int io_submit_init(struct ext4_io_submit *io,
 321                           struct inode *inode,
 322                           struct writeback_control *wbc,
 323                           struct buffer_head *bh)
 324 {
 325         ext4_io_end_t *io_end;
 326         struct page *page = bh->b_page;
 327         int nvecs = bio_get_nr_vecs(bh->b_bdev);
 328         struct bio *bio;
 329
 330         io_end = ext4_init_io_end(inode, GFP_NOFS);
 331         if (!io_end)
 332                 return -ENOMEM;
 333         bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
 334         bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 335         bio->bi_bdev = bh->b_bdev;
 336         bio->bi_private = io->io_end = io_end;
 337         bio->bi_end_io = ext4_end_bio;
 338
 339         io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
 340
 341         io->io_bio = bio;
 342         io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
 343         io->io_next_block = bh->b_blocknr;
 344         return 0;
 345 }
 346
 347 static int io_submit_add_bh(struct ext4_io_submit *io,
 348                             struct ext4_io_page *io_page,
 349                             struct inode *inode,
 350                             struct writeback_control *wbc,
 351                             struct buffer_head *bh)
 352 {
 353         ext4_io_end_t *io_end;
 354         int ret;
 355
 356         if (buffer_new(bh)) {
 357                 clear_buffer_new(bh);
 358                 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 359         }
 360
 361         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 362 submit_and_retry:
 363                 ext4_io_submit(io);
 364         }
 365         if (io->io_bio == NULL) {
 366                 ret = io_submit_init(io, inode, wbc, bh);
 367                 if (ret)
 368                         return ret;
 369         }
 370         io_end = io->io_end;
 371         if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
 372             (io_end->pages[io_end->num_io_pages-1] != io_page))
 373                 goto submit_and_retry;
 374         if (buffer_uninit(bh))
 375                 ext4_set_io_unwritten_flag(inode, io_end);
 376         io->io_end->size += bh->b_size;
 377         io->io_next_block++;
 378         ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
 379         if (ret != bh->b_size)
 380                 goto submit_and_retry;
 381         if ((io_end->num_io_pages == 0) ||
 382             (io_end->pages[io_end->num_io_pages-1] != io_page)) {
 383                 io_end->pages[io_end->num_io_pages++] = io_page;
 384                 atomic_inc(&io_page->p_count);
 385         }
 386         return 0;
 387 }
 388
 389 int ext4_bio_write_page(struct ext4_io_submit *io,
 390                         struct page *page,
 391                         int len,
 392                         struct writeback_control *wbc)
 393 {
 394         struct inode *inode = page->mapping->host;
 395         unsigned block_start, block_end, blocksize;
 396         struct ext4_io_page *io_page;
 397         struct buffer_head *bh, *head;
 398         int ret = 0;
 399
 400         blocksize = 1 << inode->i_blkbits;
 401
 402         BUG_ON(!PageLocked(page));
 403         BUG_ON(PageWriteback(page));
 404
 405         io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
 406         if (!io_page) {
 407                 redirty_page_for_writepage(wbc, page);
 408                 unlock_page(page);
 409                 return -ENOMEM;
 410         }
 411         io_page->p_page = page;
 412         atomic_set(&io_page->p_count, 1);
 413         get_page(page);
 414         set_page_writeback(page);
 415         ClearPageError(page);
 416
 417         for (bh = head = page_buffers(page), block_start = 0;
 418              bh != head || !block_start;
 419              block_start = block_end, bh = bh->b_this_page) {
 420
 421                 block_end = block_start + blocksize;
 422                 if (block_start >= len) {
 423                         /*
 424                          * Comments copied from block_write_full_page_endio:
 425                          *
 426                          * The page straddles i_size.  It must be zeroed out on
 427                          * each and every writepage invocation because it may
 428                          * be mmapped.  "A file is mapped in multiples of the
 429                          * page size.  For a file that is not a multiple of
 430                          * the  page size, the remaining memory is zeroed when
 431                          * mapped, and writes to that region are not written
 432                          * out to the file."
 433                          */
 434                         zero_user_segment(page, block_start, block_end);
 435                         clear_buffer_dirty(bh);
 436                         set_buffer_uptodate(bh);
 437                         continue;
 438                 }
 439                 if (!buffer_dirty(bh) || buffer_delay(bh) ||
 440                     !buffer_mapped(bh) || buffer_unwritten(bh)) {
 441                         /* A hole? We can safely clear the dirty bit */
 442                         if (!buffer_mapped(bh))
 443                                 clear_buffer_dirty(bh);
 444                         if (io->io_bio)
 445                                 ext4_io_submit(io);
 446                         continue;
 447                 }
 448                 ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
 449                 if (ret) {
 450                         /*
 451                          * We only get here on ENOMEM.  Not much else
 452                          * we can do but mark the page as dirty, and
 453                          * better luck next time.
 454                          */
 455                         redirty_page_for_writepage(wbc, page);
 456                         break;
 457                 }
 458                 clear_buffer_dirty(bh);
 459         }
 460         unlock_page(page);
 461         /*
 462          * If the page was truncated before we could do the writeback,
 463          * or we had a memory allocation error while trying to write
 464          * the first buffer head, we won't have submitted any pages for
 465          * I/O.  In that case we need to make sure we've cleared the
 466          * PageWriteback bit from the page to prevent the system from
 467          * wedging later on.
 468          */
 469         put_io_page(io_page);
 470         return ret;
 471 }