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/module.h>
  10 #include <linux/fs.h>
  11 #include <linux/time.h>
  12 #include <linux/jbd2.h>
  13 #include <linux/highuid.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/quotaops.h>
  16 #include <linux/string.h>
  17 #include <linux/buffer_head.h>
  18 #include <linux/writeback.h>
  19 #include <linux/pagevec.h>
  20 #include <linux/mpage.h>
  21 #include <linux/namei.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
  28 #include "ext4_jbd2.h"
  29 #include "xattr.h"
  30 #include "acl.h"
  31 #include "ext4_extents.h"
  32
  33 static struct kmem_cache *io_page_cachep, *io_end_cachep;
  34
  35 int __init ext4_init_pageio(void)
  36 {
  37         io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
  38         if (io_page_cachep == NULL)
  39                 return -ENOMEM;
  40         io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
  41         if (io_end_cachep == NULL) {
  42                 kmem_cache_destroy(io_page_cachep);
  43                 return -ENOMEM;
  44         }
  45         return 0;
  46 }
  47
  48 void ext4_exit_pageio(void)
  49 {
  50         kmem_cache_destroy(io_end_cachep);
  51         kmem_cache_destroy(io_page_cachep);
  52 }
  53
  54 void ext4_ioend_wait(struct inode *inode)
  55 {
  56         wait_queue_head_t *wq = ext4_ioend_wq(inode);
  57
  58         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
  59 }
  60
  61 static void put_io_page(struct ext4_io_page *io_page)
  62 {
  63         if (atomic_dec_and_test(&io_page->p_count)) {
  64                 end_page_writeback(io_page->p_page);
  65                 put_page(io_page->p_page);
  66                 kmem_cache_free(io_page_cachep, io_page);
  67         }
  68 }
  69
  70 void ext4_free_io_end(ext4_io_end_t *io)
  71 {
  72         int i;
  73         wait_queue_head_t *wq;
  74
  75         BUG_ON(!io);
  76         if (io->page)
  77                 put_page(io->page);
  78         for (i = 0; i < io->num_io_pages; i++)
  79                 put_io_page(io->pages[i]);
  80         io->num_io_pages = 0;
  81         wq = ext4_ioend_wq(io->inode);
  82         if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count) &&
  83             waitqueue_active(wq))
  84                 wake_up_all(wq);
  85         kmem_cache_free(io_end_cachep, io);
  86 }
  87
  88 /*
  89  * check a range of space and convert unwritten extents to written.
  90  */
  91 int ext4_end_io_nolock(ext4_io_end_t *io)
  92 {
  93         struct inode *inode = io->inode;
  94         loff_t offset = io->offset;
  95         ssize_t size = io->size;
  96         wait_queue_head_t *wq;
  97         int ret = 0;
  98
  99         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
 100                    "list->prev 0x%p\n",
 101                    io, inode->i_ino, io->list.next, io->list.prev);
 102
 103         if (list_empty(&io->list))
 104                 return ret;
 105
 106         if (!(io->flag & EXT4_IO_END_UNWRITTEN))
 107                 return ret;
 108
 109         ret = ext4_convert_unwritten_extents(inode, offset, size);
 110         if (ret < 0) {
 111                 printk(KERN_EMERG "%s: failed to convert unwritten "
 112                         "extents to written extents, error is %d "
 113                         "io is still on inode %lu aio dio list\n",
 114                        __func__, ret, inode->i_ino);
 115                 return ret;
 116         }
 117
 118         if (io->iocb)
 119                 aio_complete(io->iocb, io->result, 0);
 120         /* clear the DIO AIO unwritten flag */
 121         if (io->flag & EXT4_IO_END_UNWRITTEN) {
 122                 io->flag &= ~EXT4_IO_END_UNWRITTEN;
 123                 /* Wake up anyone waiting on unwritten extent conversion */
 124                 wq = ext4_ioend_wq(io->inode);
 125                 if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten) &&
 126                     waitqueue_active(wq)) {
 127                         wake_up_all(wq);
 128                 }
 129         }
 130
 131         return ret;
 132 }
 133
 134 /*
 135  * work on completed aio dio IO, to convert unwritten extents to extents
 136  */
 137 static void ext4_end_io_work(struct work_struct *work)
 138 {
 139         ext4_io_end_t           *io = container_of(work, ext4_io_end_t, work);
 140         struct inode            *inode = io->inode;
 141         struct ext4_inode_info  *ei = EXT4_I(inode);
 142         unsigned long           flags;
 143         int                     ret;
 144
 145         mutex_lock(&inode->i_mutex);
 146         ret = ext4_end_io_nolock(io);
 147         if (ret < 0) {
 148                 mutex_unlock(&inode->i_mutex);
 149                 return;
 150         }
 151
 152         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 153         if (!list_empty(&io->list))
 154                 list_del_init(&io->list);
 155         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 156         mutex_unlock(&inode->i_mutex);
 157         ext4_free_io_end(io);
 158 }
 159
 160 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 161 {
 162         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 163         if (io) {
 164                 atomic_inc(&EXT4_I(inode)->i_ioend_count);
 165                 io->inode = inode;
 166                 INIT_WORK(&io->work, ext4_end_io_work);
 167                 INIT_LIST_HEAD(&io->list);
 168         }
 169         return io;
 170 }
 171
 172 /*
 173  * Print an buffer I/O error compatible with the fs/buffer.c.  This
 174  * provides compatibility with dmesg scrapers that look for a specific
 175  * buffer I/O error message.  We really need a unified error reporting
 176  * structure to userspace ala Digital Unix's uerf system, but it's
 177  * probably not going to happen in my lifetime, due to LKML politics...
 178  */
 179 static void buffer_io_error(struct buffer_head *bh)
 180 {
 181         char b[BDEVNAME_SIZE];
 182         printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
 183                         bdevname(bh->b_bdev, b),
 184                         (unsigned long long)bh->b_blocknr);
 185 }
 186
 187 static void ext4_end_bio(struct bio *bio, int error)
 188 {
 189         ext4_io_end_t *io_end = bio->bi_private;
 190         struct workqueue_struct *wq;
 191         struct inode *inode;
 192         unsigned long flags;
 193         int i;
 194         sector_t bi_sector = bio->bi_sector;
 195
 196         BUG_ON(!io_end);
 197         bio->bi_private = NULL;
 198         bio->bi_end_io = NULL;
 199         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
 200                 error = 0;
 201         bio_put(bio);
 202
 203         for (i = 0; i < io_end->num_io_pages; i++) {
 204                 struct page *page = io_end->pages[i]->p_page;
 205                 struct buffer_head *bh, *head;
 206                 int partial_write = 0;
 207
 208                 head = page_buffers(page);
 209                 if (error)
 210                         SetPageError(page);
 211                 BUG_ON(!head);
 212                 if (head->b_size != PAGE_CACHE_SIZE) {
 213                         loff_t offset;
 214                         loff_t io_end_offset = io_end->offset + io_end->size;
 215
 216                         offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
 217                         bh = head;
 218                         do {
 219                                 if ((offset >= io_end->offset) &&
 220                                     (offset+bh->b_size <= io_end_offset)) {
 221                                         if (error)
 222                                                 buffer_io_error(bh);
 223
 224                                 }
 225                                 if (buffer_delay(bh))
 226                                         partial_write = 1;
 227                                 else if (!buffer_mapped(bh))
 228                                         clear_buffer_dirty(bh);
 229                                 else if (buffer_dirty(bh))
 230                                         partial_write = 1;
 231                                 offset += bh->b_size;
 232                                 bh = bh->b_this_page;
 233                         } while (bh != head);
 234                 }
 235
 236                 /*
 237                  * If this is a partial write which happened to make
 238                  * all buffers uptodate then we can optimize away a
 239                  * bogus readpage() for the next read(). Here we
 240                  * 'discover' whether the page went uptodate as a
 241                  * result of this (potentially partial) write.
 242                  */
 243                 if (!partial_write)
 244                         SetPageUptodate(page);
 245
 246                 put_io_page(io_end->pages[i]);
 247         }
 248         io_end->num_io_pages = 0;
 249         inode = io_end->inode;
 250
 251         if (error) {
 252                 io_end->flag |= EXT4_IO_END_ERROR;
 253                 ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
 254                              "(offset %llu size %ld starting block %llu)",
 255                              inode->i_ino,
 256                              (unsigned long long) io_end->offset,
 257                              (long) io_end->size,
 258                              (unsigned long long)
 259                              bi_sector >> (inode->i_blkbits - 9));
 260         }
 261
 262         /* Add the io_end to per-inode completed io list*/
 263         spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
 264         list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
 265         spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
 266
 267         wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
 268         /* queue the work to convert unwritten extents to written */
 269         queue_work(wq, &io_end->work);
 270 }
 271
 272 void ext4_io_submit(struct ext4_io_submit *io)
 273 {
 274         struct bio *bio = io->io_bio;
 275
 276         if (bio) {
 277                 bio_get(io->io_bio);
 278                 submit_bio(io->io_op, io->io_bio);
 279                 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
 280                 bio_put(io->io_bio);
 281         }
 282         io->io_bio = 0;
 283         io->io_op = 0;
 284         io->io_end = 0;
 285 }
 286
 287 static int io_submit_init(struct ext4_io_submit *io,
 288                           struct inode *inode,
 289                           struct writeback_control *wbc,
 290                           struct buffer_head *bh)
 291 {
 292         ext4_io_end_t *io_end;
 293         struct page *page = bh->b_page;
 294         int nvecs = bio_get_nr_vecs(bh->b_bdev);
 295         struct bio *bio;
 296
 297         io_end = ext4_init_io_end(inode, GFP_NOFS);
 298         if (!io_end)
 299                 return -ENOMEM;
 300         do {
 301                 bio = bio_alloc(GFP_NOIO, nvecs);
 302                 nvecs >>= 1;
 303         } while (bio == NULL);
 304
 305         bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 306         bio->bi_bdev = bh->b_bdev;
 307         bio->bi_private = io->io_end = io_end;
 308         bio->bi_end_io = ext4_end_bio;
 309
 310         io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
 311
 312         io->io_bio = bio;
 313         io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?
 314                         WRITE_SYNC_PLUG : WRITE);
 315         io->io_next_block = bh->b_blocknr;
 316         return 0;
 317 }
 318
 319 static int io_submit_add_bh(struct ext4_io_submit *io,
 320                             struct ext4_io_page *io_page,
 321                             struct inode *inode,
 322                             struct writeback_control *wbc,
 323                             struct buffer_head *bh)
 324 {
 325         ext4_io_end_t *io_end;
 326         int ret;
 327
 328         if (buffer_new(bh)) {
 329                 clear_buffer_new(bh);
 330                 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 331         }
 332
 333         if (!buffer_mapped(bh) || buffer_delay(bh)) {
 334                 if (!buffer_mapped(bh))
 335                         clear_buffer_dirty(bh);
 336                 if (io->io_bio)
 337                         ext4_io_submit(io);
 338                 return 0;
 339         }
 340
 341         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 342 submit_and_retry:
 343                 ext4_io_submit(io);
 344         }
 345         if (io->io_bio == NULL) {
 346                 ret = io_submit_init(io, inode, wbc, bh);
 347                 if (ret)
 348                         return ret;
 349         }
 350         io_end = io->io_end;
 351         if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
 352             (io_end->pages[io_end->num_io_pages-1] != io_page))
 353                 goto submit_and_retry;
 354         if (buffer_uninit(bh))
 355                 io->io_end->flag |= EXT4_IO_END_UNWRITTEN;
 356         io->io_end->size += bh->b_size;
 357         io->io_next_block++;
 358         ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
 359         if (ret != bh->b_size)
 360                 goto submit_and_retry;
 361         if ((io_end->num_io_pages == 0) ||
 362             (io_end->pages[io_end->num_io_pages-1] != io_page)) {
 363                 io_end->pages[io_end->num_io_pages++] = io_page;
 364                 atomic_inc(&io_page->p_count);
 365         }
 366         return 0;
 367 }
 368
 369 int ext4_bio_write_page(struct ext4_io_submit *io,
 370                         struct page *page,
 371                         int len,
 372                         struct writeback_control *wbc)
 373 {
 374         struct inode *inode = page->mapping->host;
 375         unsigned block_start, block_end, blocksize;
 376         struct ext4_io_page *io_page;
 377         struct buffer_head *bh, *head;
 378         int ret = 0;
 379
 380         blocksize = 1 << inode->i_blkbits;
 381
 382         BUG_ON(!PageLocked(page));
 383         BUG_ON(PageWriteback(page));
 384         set_page_writeback(page);
 385         ClearPageError(page);
 386
 387         io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
 388         if (!io_page) {
 389                 set_page_dirty(page);
 390                 unlock_page(page);
 391                 return -ENOMEM;
 392         }
 393         io_page->p_page = page;
 394         atomic_set(&io_page->p_count, 1);
 395         get_page(page);
 396
 397         for (bh = head = page_buffers(page), block_start = 0;
 398              bh != head || !block_start;
 399              block_start = block_end, bh = bh->b_this_page) {
 400
 401                 block_end = block_start + blocksize;
 402                 if (block_start >= len) {
 403                         clear_buffer_dirty(bh);
 404                         set_buffer_uptodate(bh);
 405                         continue;
 406                 }
 407                 clear_buffer_dirty(bh);
 408                 ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
 409                 if (ret) {
 410                         /*
 411                          * We only get here on ENOMEM.  Not much else
 412                          * we can do but mark the page as dirty, and
 413                          * better luck next time.
 414                          */
 415                         set_page_dirty(page);
 416                         break;
 417                 }
 418         }
 419         unlock_page(page);
 420         /*
 421          * If the page was truncated before we could do the writeback,
 422          * or we had a memory allocation error while trying to write
 423          * the first buffer head, we won't have submitted any pages for
 424          * I/O.  In that case we need to make sure we've cleared the
 425          * PageWriteback bit from the page to prevent the system from
 426          * wedging later on.
 427          */
 428         put_io_page(io_page);
 429         return ret;
 430 }