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  * Called with inode->i_mutex; we depend on this when we manipulate
  92  * io->flag, since we could otherwise race with ext4_flush_completed_IO()
  93  */
  94 int ext4_end_io_nolock(ext4_io_end_t *io)
  95 {
  96         struct inode *inode = io->inode;
  97         loff_t offset = io->offset;
  98         ssize_t size = io->size;
  99         wait_queue_head_t *wq;
 100         int ret = 0;
 101
 102         ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
 103                    "list->prev 0x%p\n",
 104                    io, inode->i_ino, io->list.next, io->list.prev);
 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         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 146         if (list_empty(&io->list)) {
 147                 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 148                 goto free;
 149         }
 150         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 151
 152         if (!mutex_trylock(&inode->i_mutex)) {
 153                 /*
 154                  * Requeue the work instead of waiting so that the work
 155                  * items queued after this can be processed.
 156                  */
 157                 queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work);
 158                 /*
 159                  * To prevent the ext4-dio-unwritten thread from keeping
 160                  * requeueing end_io requests and occupying cpu for too long,
 161                  * yield the cpu if it sees an end_io request that has already
 162                  * been requeued.
 163                  */
 164                 if (io->flag & EXT4_IO_END_QUEUED)
 165                         yield();
 166                 io->flag |= EXT4_IO_END_QUEUED;
 167                 return;
 168         }
 169         ret = ext4_end_io_nolock(io);
 170         if (ret < 0) {
 171                 mutex_unlock(&inode->i_mutex);
 172                 return;
 173         }
 174
 175         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 176         if (!list_empty(&io->list))
 177                 list_del_init(&io->list);
 178         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
 179         mutex_unlock(&inode->i_mutex);
 180 free:
 181         ext4_free_io_end(io);
 182 }
 183
 184 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 185 {
 186         ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
 187         if (io) {
 188                 atomic_inc(&EXT4_I(inode)->i_ioend_count);
 189                 io->inode = inode;
 190                 INIT_WORK(&io->work, ext4_end_io_work);
 191                 INIT_LIST_HEAD(&io->list);
 192         }
 193         return io;
 194 }
 195
 196 /*
 197  * Print an buffer I/O error compatible with the fs/buffer.c.  This
 198  * provides compatibility with dmesg scrapers that look for a specific
 199  * buffer I/O error message.  We really need a unified error reporting
 200  * structure to userspace ala Digital Unix's uerf system, but it's
 201  * probably not going to happen in my lifetime, due to LKML politics...
 202  */
 203 static void buffer_io_error(struct buffer_head *bh)
 204 {
 205         char b[BDEVNAME_SIZE];
 206         printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
 207                         bdevname(bh->b_bdev, b),
 208                         (unsigned long long)bh->b_blocknr);
 209 }
 210
 211 static void ext4_end_bio(struct bio *bio, int error)
 212 {
 213         ext4_io_end_t *io_end = bio->bi_private;
 214         struct workqueue_struct *wq;
 215         struct inode *inode;
 216         unsigned long flags;
 217         int i;
 218         sector_t bi_sector = bio->bi_sector;
 219
 220         BUG_ON(!io_end);
 221         bio->bi_private = NULL;
 222         bio->bi_end_io = NULL;
 223         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
 224                 error = 0;
 225         bio_put(bio);
 226
 227         for (i = 0; i < io_end->num_io_pages; i++) {
 228                 struct page *page = io_end->pages[i]->p_page;
 229                 struct buffer_head *bh, *head;
 230                 loff_t offset;
 231                 loff_t io_end_offset;
 232
 233                 if (error) {
 234                         SetPageError(page);
 235                         set_bit(AS_EIO, &page->mapping->flags);
 236                         head = page_buffers(page);
 237                         BUG_ON(!head);
 238
 239                         io_end_offset = io_end->offset + io_end->size;
 240
 241                         offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
 242                         bh = head;
 243                         do {
 244                                 if ((offset >= io_end->offset) &&
 245                                     (offset+bh->b_size <= io_end_offset))
 246                                         buffer_io_error(bh);
 247
 248                                 offset += bh->b_size;
 249                                 bh = bh->b_this_page;
 250                         } while (bh != head);
 251                 }
 252
 253                 put_io_page(io_end->pages[i]);
 254         }
 255         io_end->num_io_pages = 0;
 256         inode = io_end->inode;
 257
 258         if (error) {
 259                 io_end->flag |= EXT4_IO_END_ERROR;
 260                 ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
 261                              "(offset %llu size %ld starting block %llu)",
 262                              inode->i_ino,
 263                              (unsigned long long) io_end->offset,
 264                              (long) io_end->size,
 265                              (unsigned long long)
 266                              bi_sector >> (inode->i_blkbits - 9));
 267         }
 268
 269         if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
 270                 ext4_free_io_end(io_end);
 271                 return;
 272         }
 273
 274         /* Add the io_end to per-inode completed io list*/
 275         spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
 276         list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
 277         spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
 278
 279         wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
 280         /* queue the work to convert unwritten extents to written */
 281         queue_work(wq, &io_end->work);
 282 }
 283
 284 void ext4_io_submit(struct ext4_io_submit *io)
 285 {
 286         struct bio *bio = io->io_bio;
 287
 288         if (bio) {
 289                 bio_get(io->io_bio);
 290                 submit_bio(io->io_op, io->io_bio);
 291                 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
 292                 bio_put(io->io_bio);
 293         }
 294         io->io_bio = NULL;
 295         io->io_op = 0;
 296         io->io_end = NULL;
 297 }
 298
 299 static int io_submit_init(struct ext4_io_submit *io,
 300                           struct inode *inode,
 301                           struct writeback_control *wbc,
 302                           struct buffer_head *bh)
 303 {
 304         ext4_io_end_t *io_end;
 305         struct page *page = bh->b_page;
 306         int nvecs = bio_get_nr_vecs(bh->b_bdev);
 307         struct bio *bio;
 308
 309         io_end = ext4_init_io_end(inode, GFP_NOFS);
 310         if (!io_end)
 311                 return -ENOMEM;
 312         bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
 313         bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 314         bio->bi_bdev = bh->b_bdev;
 315         bio->bi_private = io->io_end = io_end;
 316         bio->bi_end_io = ext4_end_bio;
 317
 318         io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
 319
 320         io->io_bio = bio;
 321         io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
 322         io->io_next_block = bh->b_blocknr;
 323         return 0;
 324 }
 325
 326 static int io_submit_add_bh(struct ext4_io_submit *io,
 327                             struct ext4_io_page *io_page,
 328                             struct inode *inode,
 329                             struct writeback_control *wbc,
 330                             struct buffer_head *bh)
 331 {
 332         ext4_io_end_t *io_end;
 333         int ret;
 334
 335         if (buffer_new(bh)) {
 336                 clear_buffer_new(bh);
 337                 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 338         }
 339
 340         if (!buffer_mapped(bh) || buffer_delay(bh)) {
 341                 if (!buffer_mapped(bh))
 342                         clear_buffer_dirty(bh);
 343                 if (io->io_bio)
 344                         ext4_io_submit(io);
 345                 return 0;
 346         }
 347
 348         if (io->io_bio && bh->b_blocknr != io->io_next_block) {
 349 submit_and_retry:
 350                 ext4_io_submit(io);
 351         }
 352         if (io->io_bio == NULL) {
 353                 ret = io_submit_init(io, inode, wbc, bh);
 354                 if (ret)
 355                         return ret;
 356         }
 357         io_end = io->io_end;
 358         if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
 359             (io_end->pages[io_end->num_io_pages-1] != io_page))
 360                 goto submit_and_retry;
 361         if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
 362                 io_end->flag |= EXT4_IO_END_UNWRITTEN;
 363                 atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
 364         }
 365         io->io_end->size += bh->b_size;
 366         io->io_next_block++;
 367         ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
 368         if (ret != bh->b_size)
 369                 goto submit_and_retry;
 370         if ((io_end->num_io_pages == 0) ||
 371             (io_end->pages[io_end->num_io_pages-1] != io_page)) {
 372                 io_end->pages[io_end->num_io_pages++] = io_page;
 373                 atomic_inc(&io_page->p_count);
 374         }
 375         return 0;
 376 }
 377
 378 int ext4_bio_write_page(struct ext4_io_submit *io,
 379                         struct page *page,
 380                         int len,
 381                         struct writeback_control *wbc)
 382 {
 383         struct inode *inode = page->mapping->host;
 384         unsigned block_start, block_end, blocksize;
 385         struct ext4_io_page *io_page;
 386         struct buffer_head *bh, *head;
 387         int ret = 0;
 388
 389         blocksize = 1 << inode->i_blkbits;
 390
 391         BUG_ON(!PageLocked(page));
 392         BUG_ON(PageWriteback(page));
 393
 394         io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
 395         if (!io_page) {
 396                 set_page_dirty(page);
 397                 unlock_page(page);
 398                 return -ENOMEM;
 399         }
 400         io_page->p_page = page;
 401         atomic_set(&io_page->p_count, 1);
 402         get_page(page);
 403         set_page_writeback(page);
 404         ClearPageError(page);
 405
 406         for (bh = head = page_buffers(page), block_start = 0;
 407              bh != head || !block_start;
 408              block_start = block_end, bh = bh->b_this_page) {
 409
 410                 block_end = block_start + blocksize;
 411                 if (block_start >= len) {
 412                         clear_buffer_dirty(bh);
 413                         set_buffer_uptodate(bh);
 414                         continue;
 415                 }
 416                 clear_buffer_dirty(bh);
 417                 ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
 418                 if (ret) {
 419                         /*
 420                          * We only get here on ENOMEM.  Not much else
 421                          * we can do but mark the page as dirty, and
 422                          * better luck next time.
 423                          */
 424                         set_page_dirty(page);
 425                         break;
 426                 }
 427         }
 428         unlock_page(page);
 429         /*
 430          * If the page was truncated before we could do the writeback,
 431          * or we had a memory allocation error while trying to write
 432          * the first buffer head, we won't have submitted any pages for
 433          * I/O.  In that case we need to make sure we've cleared the
 434          * PageWriteback bit from the page to prevent the system from
 435          * wedging later on.
 436          */
 437         put_io_page(io_page);
 438         return ret;
 439 }