fs/f2fs/data.c

   1 /*
   2  * fs/f2fs/data.c
   3  *
   4  * Copyright (c) 2012 Samsung Electronics Co., Ltd.
   5  *             http://www.samsung.com/
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/fs.h>
  12 #include <linux/f2fs_fs.h>
  13 #include <linux/buffer_head.h>
  14 #include <linux/mpage.h>
  15 #include <linux/aio.h>
  16 #include <linux/writeback.h>
  17 #include <linux/backing-dev.h>
  18 #include <linux/blkdev.h>
  19 #include <linux/bio.h>
  20 #include <linux/prefetch.h>
  21
  22 #include "f2fs.h"
  23 #include "node.h"
  24 #include "segment.h"
  25 #include <trace/events/f2fs.h>
  26
  27 /*
  28  * Lock ordering for the change of data block address:
  29  * ->data_page
  30  *  ->node_page
  31  *    update block addresses in the node page
  32  */
  33 static void __set_data_blkaddr(struct dnode_of_data *dn, block_t new_addr)
  34 {
  35         struct f2fs_node *rn;
  36         __le32 *addr_array;
  37         struct page *node_page = dn->node_page;
  38         unsigned int ofs_in_node = dn->ofs_in_node;
  39
  40         f2fs_wait_on_page_writeback(node_page, NODE, false);
  41
  42         rn = F2FS_NODE(node_page);
  43
  44         /* Get physical address of data block */
  45         addr_array = blkaddr_in_node(rn);
  46         addr_array[ofs_in_node] = cpu_to_le32(new_addr);
  47         set_page_dirty(node_page);
  48 }
  49
  50 int reserve_new_block(struct dnode_of_data *dn)
  51 {
  52         struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
  53
  54         if (is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC))
  55                 return -EPERM;
  56         if (!inc_valid_block_count(sbi, dn->inode, 1))
  57                 return -ENOSPC;
  58
  59         trace_f2fs_reserve_new_block(dn->inode, dn->nid, dn->ofs_in_node);
  60
  61         __set_data_blkaddr(dn, NEW_ADDR);
  62         dn->data_blkaddr = NEW_ADDR;
  63         sync_inode_page(dn);
  64         return 0;
  65 }
  66
  67 static int check_extent_cache(struct inode *inode, pgoff_t pgofs,
  68                                         struct buffer_head *bh_result)
  69 {
  70         struct f2fs_inode_info *fi = F2FS_I(inode);
  71         pgoff_t start_fofs, end_fofs;
  72         block_t start_blkaddr;
  73
  74         read_lock(&fi->ext.ext_lock);
  75         if (fi->ext.len == 0) {
  76                 read_unlock(&fi->ext.ext_lock);
  77                 return 0;
  78         }
  79
  80         stat_inc_total_hit(inode->i_sb);
  81
  82         start_fofs = fi->ext.fofs;
  83         end_fofs = fi->ext.fofs + fi->ext.len - 1;
  84         start_blkaddr = fi->ext.blk_addr;
  85
  86         if (pgofs >= start_fofs && pgofs <= end_fofs) {
  87                 unsigned int blkbits = inode->i_sb->s_blocksize_bits;
  88                 size_t count;
  89
  90                 clear_buffer_new(bh_result);
  91                 map_bh(bh_result, inode->i_sb,
  92                                 start_blkaddr + pgofs - start_fofs);
  93                 count = end_fofs - pgofs + 1;
  94                 if (count < (UINT_MAX >> blkbits))
  95                         bh_result->b_size = (count << blkbits);
  96                 else
  97                         bh_result->b_size = UINT_MAX;
  98
  99                 stat_inc_read_hit(inode->i_sb);
 100                 read_unlock(&fi->ext.ext_lock);
 101                 return 1;
 102         }
 103         read_unlock(&fi->ext.ext_lock);
 104         return 0;
 105 }
 106
 107 void update_extent_cache(block_t blk_addr, struct dnode_of_data *dn)
 108 {
 109         struct f2fs_inode_info *fi = F2FS_I(dn->inode);
 110         pgoff_t fofs, start_fofs, end_fofs;
 111         block_t start_blkaddr, end_blkaddr;
 112
 113         f2fs_bug_on(blk_addr == NEW_ADDR);
 114         fofs = start_bidx_of_node(ofs_of_node(dn->node_page), fi) +
 115                                                         dn->ofs_in_node;
 116
 117         /* Update the page address in the parent node */
 118         __set_data_blkaddr(dn, blk_addr);
 119
 120         write_lock(&fi->ext.ext_lock);
 121
 122         start_fofs = fi->ext.fofs;
 123         end_fofs = fi->ext.fofs + fi->ext.len - 1;
 124         start_blkaddr = fi->ext.blk_addr;
 125         end_blkaddr = fi->ext.blk_addr + fi->ext.len - 1;
 126
 127         /* Drop and initialize the matched extent */
 128         if (fi->ext.len == 1 && fofs == start_fofs)
 129                 fi->ext.len = 0;
 130
 131         /* Initial extent */
 132         if (fi->ext.len == 0) {
 133                 if (blk_addr != NULL_ADDR) {
 134                         fi->ext.fofs = fofs;
 135                         fi->ext.blk_addr = blk_addr;
 136                         fi->ext.len = 1;
 137                 }
 138                 goto end_update;
 139         }
 140
 141         /* Front merge */
 142         if (fofs == start_fofs - 1 && blk_addr == start_blkaddr - 1) {
 143                 fi->ext.fofs--;
 144                 fi->ext.blk_addr--;
 145                 fi->ext.len++;
 146                 goto end_update;
 147         }
 148
 149         /* Back merge */
 150         if (fofs == end_fofs + 1 && blk_addr == end_blkaddr + 1) {
 151                 fi->ext.len++;
 152                 goto end_update;
 153         }
 154
 155         /* Split the existing extent */
 156         if (fi->ext.len > 1 &&
 157                 fofs >= start_fofs && fofs <= end_fofs) {
 158                 if ((end_fofs - fofs) < (fi->ext.len >> 1)) {
 159                         fi->ext.len = fofs - start_fofs;
 160                 } else {
 161                         fi->ext.fofs = fofs + 1;
 162                         fi->ext.blk_addr = start_blkaddr +
 163                                         fofs - start_fofs + 1;
 164                         fi->ext.len -= fofs - start_fofs + 1;
 165                 }
 166                 goto end_update;
 167         }
 168         write_unlock(&fi->ext.ext_lock);
 169         return;
 170
 171 end_update:
 172         write_unlock(&fi->ext.ext_lock);
 173         sync_inode_page(dn);
 174 }
 175
 176 struct page *find_data_page(struct inode *inode, pgoff_t index, bool sync)
 177 {
 178         struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 179         struct address_space *mapping = inode->i_mapping;
 180         struct dnode_of_data dn;
 181         struct page *page;
 182         int err;
 183
 184         page = find_get_page(mapping, index);
 185         if (page && PageUptodate(page))
 186                 return page;
 187         f2fs_put_page(page, 0);
 188
 189         set_new_dnode(&dn, inode, NULL, NULL, 0);
 190         err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
 191         if (err)
 192                 return ERR_PTR(err);
 193         f2fs_put_dnode(&dn);
 194
 195         if (dn.data_blkaddr == NULL_ADDR)
 196                 return ERR_PTR(-ENOENT);
 197
 198         /* By fallocate(), there is no cached page, but with NEW_ADDR */
 199         if (dn.data_blkaddr == NEW_ADDR)
 200                 return ERR_PTR(-EINVAL);
 201
 202         page = grab_cache_page_write_begin(mapping, index, AOP_FLAG_NOFS);
 203         if (!page)
 204                 return ERR_PTR(-ENOMEM);
 205
 206         if (PageUptodate(page)) {
 207                 unlock_page(page);
 208                 return page;
 209         }
 210
 211         err = f2fs_readpage(sbi, page, dn.data_blkaddr,
 212                                         sync ? READ_SYNC : READA);
 213         if (sync) {
 214                 wait_on_page_locked(page);
 215                 if (!PageUptodate(page)) {
 216                         f2fs_put_page(page, 0);
 217                         return ERR_PTR(-EIO);
 218                 }
 219         }
 220         return page;
 221 }
 222
 223 /*
 224  * If it tries to access a hole, return an error.
 225  * Because, the callers, functions in dir.c and GC, should be able to know
 226  * whether this page exists or not.
 227  */
 228 struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
 229 {
 230         struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 231         struct address_space *mapping = inode->i_mapping;
 232         struct dnode_of_data dn;
 233         struct page *page;
 234         int err;
 235
 236 repeat:
 237         page = grab_cache_page_write_begin(mapping, index, AOP_FLAG_NOFS);
 238         if (!page)
 239                 return ERR_PTR(-ENOMEM);
 240
 241         set_new_dnode(&dn, inode, NULL, NULL, 0);
 242         err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
 243         if (err) {
 244                 f2fs_put_page(page, 1);
 245                 return ERR_PTR(err);
 246         }
 247         f2fs_put_dnode(&dn);
 248
 249         if (dn.data_blkaddr == NULL_ADDR) {
 250                 f2fs_put_page(page, 1);
 251                 return ERR_PTR(-ENOENT);
 252         }
 253
 254         if (PageUptodate(page))
 255                 return page;
 256
 257         /*
 258          * A new dentry page is allocated but not able to be written, since its
 259          * new inode page couldn't be allocated due to -ENOSPC.
 260          * In such the case, its blkaddr can be remained as NEW_ADDR.
 261          * see, f2fs_add_link -> get_new_data_page -> init_inode_metadata.
 262          */
 263         if (dn.data_blkaddr == NEW_ADDR) {
 264                 zero_user_segment(page, 0, PAGE_CACHE_SIZE);
 265                 SetPageUptodate(page);
 266                 return page;
 267         }
 268
 269         err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
 270         if (err)
 271                 return ERR_PTR(err);
 272
 273         lock_page(page);
 274         if (!PageUptodate(page)) {
 275                 f2fs_put_page(page, 1);
 276                 return ERR_PTR(-EIO);
 277         }
 278         if (page->mapping != mapping) {
 279                 f2fs_put_page(page, 1);
 280                 goto repeat;
 281         }
 282         return page;
 283 }
 284
 285 /*
 286  * Caller ensures that this data page is never allocated.
 287  * A new zero-filled data page is allocated in the page cache.
 288  *
 289  * Also, caller should grab and release a mutex by calling mutex_lock_op() and
 290  * mutex_unlock_op().
 291  * Note that, npage is set only by make_empty_dir.
 292  */
 293 struct page *get_new_data_page(struct inode *inode,
 294                 struct page *npage, pgoff_t index, bool new_i_size)
 295 {
 296         struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 297         struct address_space *mapping = inode->i_mapping;
 298         struct page *page;
 299         struct dnode_of_data dn;
 300         int err;
 301
 302         set_new_dnode(&dn, inode, npage, npage, 0);
 303         err = get_dnode_of_data(&dn, index, ALLOC_NODE);
 304         if (err)
 305                 return ERR_PTR(err);
 306
 307         if (dn.data_blkaddr == NULL_ADDR) {
 308                 if (reserve_new_block(&dn)) {
 309                         if (!npage)
 310                                 f2fs_put_dnode(&dn);
 311                         return ERR_PTR(-ENOSPC);
 312                 }
 313         }
 314         if (!npage)
 315                 f2fs_put_dnode(&dn);
 316 repeat:
 317         page = grab_cache_page(mapping, index);
 318         if (!page)
 319                 return ERR_PTR(-ENOMEM);
 320
 321         if (PageUptodate(page))
 322                 return page;
 323
 324         if (dn.data_blkaddr == NEW_ADDR) {
 325                 zero_user_segment(page, 0, PAGE_CACHE_SIZE);
 326                 SetPageUptodate(page);
 327         } else {
 328                 err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
 329                 if (err)
 330                         return ERR_PTR(err);
 331                 lock_page(page);
 332                 if (!PageUptodate(page)) {
 333                         f2fs_put_page(page, 1);
 334                         return ERR_PTR(-EIO);
 335                 }
 336                 if (page->mapping != mapping) {
 337                         f2fs_put_page(page, 1);
 338                         goto repeat;
 339                 }
 340         }
 341
 342         if (new_i_size &&
 343                 i_size_read(inode) < ((index + 1) << PAGE_CACHE_SHIFT)) {
 344                 i_size_write(inode, ((index + 1) << PAGE_CACHE_SHIFT));
 345                 /* Only the directory inode sets new_i_size */
 346                 set_inode_flag(F2FS_I(inode), FI_UPDATE_DIR);
 347                 mark_inode_dirty_sync(inode);
 348         }
 349         return page;
 350 }
 351
 352 static void read_end_io(struct bio *bio, int err)
 353 {
 354         struct bio_vec *bvec;
 355         int i;
 356
 357         bio_for_each_segment_all(bvec, bio, i) {
 358                 struct page *page = bvec->bv_page;
 359
 360                 if (!err) {
 361                         SetPageUptodate(page);
 362                 } else {
 363                         ClearPageUptodate(page);
 364                         SetPageError(page);
 365                 }
 366                 unlock_page(page);
 367         }
 368         bio_put(bio);
 369 }
 370
 371 /*
 372  * Fill the locked page with data located in the block address.
 373  * Return unlocked page.
 374  */
 375 int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
 376                                         block_t blk_addr, int type)
 377 {
 378         struct block_device *bdev = sbi->sb->s_bdev;
 379         struct bio *bio;
 380
 381         trace_f2fs_readpage(page, blk_addr, type);
 382
 383         down_read(&sbi->bio_sem);
 384
 385         /* Allocate a new bio */
 386         bio = f2fs_bio_alloc(bdev, 1);
 387
 388         /* Initialize the bio */
 389         bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
 390         bio->bi_end_io = read_end_io;
 391
 392         if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
 393                 bio_put(bio);
 394                 up_read(&sbi->bio_sem);
 395                 f2fs_put_page(page, 1);
 396                 return -EFAULT;
 397         }
 398
 399         submit_bio(type, bio);
 400         up_read(&sbi->bio_sem);
 401         return 0;
 402 }
 403
 404 /*
 405  * This function should be used by the data read flow only where it
 406  * does not check the "create" flag that indicates block allocation.
 407  * The reason for this special functionality is to exploit VFS readahead
 408  * mechanism.
 409  */
 410 static int get_data_block_ro(struct inode *inode, sector_t iblock,
 411                         struct buffer_head *bh_result, int create)
 412 {
 413         unsigned int blkbits = inode->i_sb->s_blocksize_bits;
 414         unsigned maxblocks = bh_result->b_size >> blkbits;
 415         struct dnode_of_data dn;
 416         pgoff_t pgofs;
 417         int err;
 418
 419         /* Get the page offset from the block offset(iblock) */
 420         pgofs = (pgoff_t)(iblock >> (PAGE_CACHE_SHIFT - blkbits));
 421
 422         if (check_extent_cache(inode, pgofs, bh_result)) {
 423                 trace_f2fs_get_data_block(inode, iblock, bh_result, 0);
 424                 return 0;
 425         }
 426
 427         /* When reading holes, we need its node page */
 428         set_new_dnode(&dn, inode, NULL, NULL, 0);
 429         err = get_dnode_of_data(&dn, pgofs, LOOKUP_NODE_RA);
 430         if (err) {
 431                 trace_f2fs_get_data_block(inode, iblock, bh_result, err);
 432                 return (err == -ENOENT) ? 0 : err;
 433         }
 434
 435         /* It does not support data allocation */
 436         f2fs_bug_on(create);
 437
 438         if (dn.data_blkaddr != NEW_ADDR && dn.data_blkaddr != NULL_ADDR) {
 439                 int i;
 440                 unsigned int end_offset;
 441
 442                 end_offset = IS_INODE(dn.node_page) ?
 443                                 ADDRS_PER_INODE(F2FS_I(inode)) :
 444                                 ADDRS_PER_BLOCK;
 445
 446                 clear_buffer_new(bh_result);
 447
 448                 /* Give more consecutive addresses for the read ahead */
 449                 for (i = 0; i < end_offset - dn.ofs_in_node; i++)
 450                         if (((datablock_addr(dn.node_page,
 451                                                         dn.ofs_in_node + i))
 452                                 != (dn.data_blkaddr + i)) || maxblocks == i)
 453                                 break;
 454                 map_bh(bh_result, inode->i_sb, dn.data_blkaddr);
 455                 bh_result->b_size = (i << blkbits);
 456         }
 457         f2fs_put_dnode(&dn);
 458         trace_f2fs_get_data_block(inode, iblock, bh_result, 0);
 459         return 0;
 460 }
 461
 462 static int f2fs_read_data_page(struct file *file, struct page *page)
 463 {
 464         return mpage_readpage(page, get_data_block_ro);
 465 }
 466
 467 static int f2fs_read_data_pages(struct file *file,
 468                         struct address_space *mapping,
 469                         struct list_head *pages, unsigned nr_pages)
 470 {
 471         return mpage_readpages(mapping, pages, nr_pages, get_data_block_ro);
 472 }
 473
 474 int do_write_data_page(struct page *page)
 475 {
 476         struct inode *inode = page->mapping->host;
 477         block_t old_blk_addr, new_blk_addr;
 478         struct dnode_of_data dn;
 479         int err = 0;
 480
 481         set_new_dnode(&dn, inode, NULL, NULL, 0);
 482         err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
 483         if (err)
 484                 return err;
 485
 486         old_blk_addr = dn.data_blkaddr;
 487
 488         /* This page is already truncated */
 489         if (old_blk_addr == NULL_ADDR)
 490                 goto out_writepage;
 491
 492         set_page_writeback(page);
 493
 494         /*
 495          * If current allocation needs SSR,
 496          * it had better in-place writes for updated data.
 497          */
 498         if (unlikely(old_blk_addr != NEW_ADDR &&
 499                         !is_cold_data(page) &&
 500                         need_inplace_update(inode))) {
 501                 rewrite_data_page(F2FS_SB(inode->i_sb), page,
 502                                                 old_blk_addr);
 503         } else {
 504                 write_data_page(inode, page, &dn,
 505                                 old_blk_addr, &new_blk_addr);
 506                 update_extent_cache(new_blk_addr, &dn);
 507         }
 508 out_writepage:
 509         f2fs_put_dnode(&dn);
 510         return err;
 511 }
 512
 513 static int f2fs_write_data_page(struct page *page,
 514                                         struct writeback_control *wbc)
 515 {
 516         struct inode *inode = page->mapping->host;
 517         struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 518         loff_t i_size = i_size_read(inode);
 519         const pgoff_t end_index = ((unsigned long long) i_size)
 520                                                         >> PAGE_CACHE_SHIFT;
 521         unsigned offset;
 522         bool need_balance_fs = false;
 523         int err = 0;
 524
 525         if (page->index < end_index)
 526                 goto write;
 527
 528         /*
 529          * If the offset is out-of-range of file size,
 530          * this page does not have to be written to disk.
 531          */
 532         offset = i_size & (PAGE_CACHE_SIZE - 1);
 533         if ((page->index >= end_index + 1) || !offset) {
 534                 if (S_ISDIR(inode->i_mode)) {
 535                         dec_page_count(sbi, F2FS_DIRTY_DENTS);
 536                         inode_dec_dirty_dents(inode);
 537                 }
 538                 goto out;
 539         }
 540
 541         zero_user_segment(page, offset, PAGE_CACHE_SIZE);
 542 write:
 543         if (sbi->por_doing) {
 544                 err = AOP_WRITEPAGE_ACTIVATE;
 545                 goto redirty_out;
 546         }
 547
 548         /* Dentry blocks are controlled by checkpoint */
 549         if (S_ISDIR(inode->i_mode)) {
 550                 dec_page_count(sbi, F2FS_DIRTY_DENTS);
 551                 inode_dec_dirty_dents(inode);
 552                 err = do_write_data_page(page);
 553         } else {
 554                 f2fs_lock_op(sbi);
 555                 err = do_write_data_page(page);
 556                 f2fs_unlock_op(sbi);
 557                 need_balance_fs = true;
 558         }
 559         if (err == -ENOENT)
 560                 goto out;
 561         else if (err)
 562                 goto redirty_out;
 563
 564         if (wbc->for_reclaim)
 565                 f2fs_submit_bio(sbi, DATA, true);
 566
 567         clear_cold_data(page);
 568 out:
 569         unlock_page(page);
 570         if (need_balance_fs)
 571                 f2fs_balance_fs(sbi);
 572         return 0;
 573
 574 redirty_out:
 575         wbc->pages_skipped++;
 576         set_page_dirty(page);
 577         return err;
 578 }
 579
 580 #define MAX_DESIRED_PAGES_WP    4096
 581
 582 static int __f2fs_writepage(struct page *page, struct writeback_control *wbc,
 583                         void *data)
 584 {
 585         struct address_space *mapping = data;
 586         int ret = mapping->a_ops->writepage(page, wbc);
 587         mapping_set_error(mapping, ret);
 588         return ret;
 589 }
 590
 591 static int f2fs_write_data_pages(struct address_space *mapping,
 592                             struct writeback_control *wbc)
 593 {
 594         struct inode *inode = mapping->host;
 595         struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 596         bool locked = false;
 597         int ret;
 598         long excess_nrtw = 0, desired_nrtw;
 599
 600         /* deal with chardevs and other special file */
 601         if (!mapping->a_ops->writepage)
 602                 return 0;
 603
 604         if (wbc->nr_to_write < MAX_DESIRED_PAGES_WP) {
 605                 desired_nrtw = MAX_DESIRED_PAGES_WP;
 606                 excess_nrtw = desired_nrtw - wbc->nr_to_write;
 607                 wbc->nr_to_write = desired_nrtw;
 608         }
 609
 610         if (!S_ISDIR(inode->i_mode)) {
 611                 mutex_lock(&sbi->writepages);
 612                 locked = true;
 613         }
 614         ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
 615         if (locked)
 616                 mutex_unlock(&sbi->writepages);
 617         f2fs_submit_bio(sbi, DATA, (wbc->sync_mode == WB_SYNC_ALL));
 618
 619         remove_dirty_dir_inode(inode);
 620
 621         wbc->nr_to_write -= excess_nrtw;
 622         return ret;
 623 }
 624
 625 static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 626                 loff_t pos, unsigned len, unsigned flags,
 627                 struct page **pagep, void **fsdata)
 628 {
 629         struct inode *inode = mapping->host;
 630         struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 631         struct page *page;
 632         pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
 633         struct dnode_of_data dn;
 634         int err = 0;
 635
 636         f2fs_balance_fs(sbi);
 637 repeat:
 638         page = grab_cache_page_write_begin(mapping, index, flags);
 639         if (!page)
 640                 return -ENOMEM;
 641         *pagep = page;
 642
 643         f2fs_lock_op(sbi);
 644
 645         set_new_dnode(&dn, inode, NULL, NULL, 0);
 646         err = get_dnode_of_data(&dn, index, ALLOC_NODE);
 647         if (err)
 648                 goto err;
 649
 650         if (dn.data_blkaddr == NULL_ADDR)
 651                 err = reserve_new_block(&dn);
 652
 653         f2fs_put_dnode(&dn);
 654         if (err)
 655                 goto err;
 656
 657         f2fs_unlock_op(sbi);
 658
 659         if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
 660                 return 0;
 661
 662         if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
 663                 unsigned start = pos & (PAGE_CACHE_SIZE - 1);
 664                 unsigned end = start + len;
 665
 666                 /* Reading beyond i_size is simple: memset to zero */
 667                 zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
 668                 goto out;
 669         }
 670
 671         if (dn.data_blkaddr == NEW_ADDR) {
 672                 zero_user_segment(page, 0, PAGE_CACHE_SIZE);
 673         } else {
 674                 err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
 675                 if (err)
 676                         return err;
 677                 lock_page(page);
 678                 if (!PageUptodate(page)) {
 679                         f2fs_put_page(page, 1);
 680                         return -EIO;
 681                 }
 682                 if (page->mapping != mapping) {
 683                         f2fs_put_page(page, 1);
 684                         goto repeat;
 685                 }
 686         }
 687 out:
 688         SetPageUptodate(page);
 689         clear_cold_data(page);
 690         return 0;
 691
 692 err:
 693         f2fs_unlock_op(sbi);
 694         f2fs_put_page(page, 1);
 695         return err;
 696 }
 697
 698 static int f2fs_write_end(struct file *file,
 699                         struct address_space *mapping,
 700                         loff_t pos, unsigned len, unsigned copied,
 701                         struct page *page, void *fsdata)
 702 {
 703         struct inode *inode = page->mapping->host;
 704
 705         SetPageUptodate(page);
 706         set_page_dirty(page);
 707
 708         if (pos + copied > i_size_read(inode)) {
 709                 i_size_write(inode, pos + copied);
 710                 mark_inode_dirty(inode);
 711                 update_inode_page(inode);
 712         }
 713
 714         unlock_page(page);
 715         page_cache_release(page);
 716         return copied;
 717 }
 718
 719 static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
 720                 const struct iovec *iov, loff_t offset, unsigned long nr_segs)
 721 {
 722         struct file *file = iocb->ki_filp;
 723         struct inode *inode = file->f_mapping->host;
 724
 725         if (rw == WRITE)
 726                 return 0;
 727
 728         /* Needs synchronization with the cleaner */
 729         return blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
 730                                                   get_data_block_ro);
 731 }
 732
 733 static void f2fs_invalidate_data_page(struct page *page, unsigned int offset,
 734                                       unsigned int length)
 735 {
 736         struct inode *inode = page->mapping->host;
 737         struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 738         if (S_ISDIR(inode->i_mode) && PageDirty(page)) {
 739                 dec_page_count(sbi, F2FS_DIRTY_DENTS);
 740                 inode_dec_dirty_dents(inode);
 741         }
 742         ClearPagePrivate(page);
 743 }
 744
 745 static int f2fs_release_data_page(struct page *page, gfp_t wait)
 746 {
 747         ClearPagePrivate(page);
 748         return 1;
 749 }
 750
 751 static int f2fs_set_data_page_dirty(struct page *page)
 752 {
 753         struct address_space *mapping = page->mapping;
 754         struct inode *inode = mapping->host;
 755
 756         trace_f2fs_set_page_dirty(page, DATA);
 757
 758         SetPageUptodate(page);
 759         if (!PageDirty(page)) {
 760                 __set_page_dirty_nobuffers(page);
 761                 set_dirty_dir_page(inode, page);
 762                 return 1;
 763         }
 764         return 0;
 765 }
 766
 767 static sector_t f2fs_bmap(struct address_space *mapping, sector_t block)
 768 {
 769         return generic_block_bmap(mapping, block, get_data_block_ro);
 770 }
 771
 772 const struct address_space_operations f2fs_dblock_aops = {
 773         .readpage       = f2fs_read_data_page,
 774         .readpages      = f2fs_read_data_pages,
 775         .writepage      = f2fs_write_data_page,
 776         .writepages     = f2fs_write_data_pages,
 777         .write_begin    = f2fs_write_begin,
 778         .write_end      = f2fs_write_end,
 779         .set_page_dirty = f2fs_set_data_page_dirty,
 780         .invalidatepage = f2fs_invalidate_data_page,
 781         .releasepage    = f2fs_release_data_page,
 782         .direct_IO      = f2fs_direct_IO,
 783         .bmap           = f2fs_bmap,
 784 };