fs/ext4/file.c

   1 /*
   2  *  linux/fs/ext4/file.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/file.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  ext4 fs regular file handling primitives
  16  *
  17  *  64-bit file support on 64-bit platforms by Jakub Jelinek
  18  *      (jj@sunsite.ms.mff.cuni.cz)
  19  */
  20
  21 #include <linux/time.h>
  22 #include <linux/fs.h>
  23 #include <linux/jbd2.h>
  24 #include <linux/mount.h>
  25 #include <linux/path.h>
  26 #include <linux/aio.h>
  27 #include <linux/quotaops.h>
  28 #include <linux/pagevec.h>
  29 #include "ext4.h"
  30 #include "ext4_jbd2.h"
  31 #include "xattr.h"
  32 #include "acl.h"
  33
  34 /*
  35  * Called when an inode is released. Note that this is different
  36  * from ext4_file_open: open gets called at every open, but release
  37  * gets called only when /all/ the files are closed.
  38  */
  39 static int ext4_release_file(struct inode *inode, struct file *filp)
  40 {
  41         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
  42                 ext4_alloc_da_blocks(inode);
  43                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
  44         }
  45         /* if we are the last writer on the inode, drop the block reservation */
  46         if ((filp->f_mode & FMODE_WRITE) &&
  47                         (atomic_read(&inode->i_writecount) == 1) &&
  48                         !EXT4_I(inode)->i_reserved_data_blocks)
  49         {
  50                 down_write(&EXT4_I(inode)->i_data_sem);
  51                 ext4_discard_preallocations(inode);
  52                 up_write(&EXT4_I(inode)->i_data_sem);
  53         }
  54         if (is_dx(inode) && filp->private_data)
  55                 ext4_htree_free_dir_info(filp->private_data);
  56
  57         return 0;
  58 }
  59
  60 static void ext4_unwritten_wait(struct inode *inode)
  61 {
  62         wait_queue_head_t *wq = ext4_ioend_wq(inode);
  63
  64         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
  65 }
  66
  67 /*
  68  * This tests whether the IO in question is block-aligned or not.
  69  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
  70  * are converted to written only after the IO is complete.  Until they are
  71  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
  72  * it needs to zero out portions of the start and/or end block.  If 2 AIO
  73  * threads are at work on the same unwritten block, they must be synchronized
  74  * or one thread will zero the other's data, causing corruption.
  75  */
  76 static int
  77 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
  78 {
  79         struct super_block *sb = inode->i_sb;
  80         int blockmask = sb->s_blocksize - 1;
  81
  82         if (pos >= i_size_read(inode))
  83                 return 0;
  84
  85         if ((pos | iov_iter_alignment(from)) & blockmask)
  86                 return 1;
  87
  88         return 0;
  89 }
  90
  91 static ssize_t
  92 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
  93 {
  94         struct file *file = iocb->ki_filp;
  95         struct inode *inode = file_inode(iocb->ki_filp);
  96         struct mutex *aio_mutex = NULL;
  97         struct blk_plug plug;
  98         int o_direct = file->f_flags & O_DIRECT;
  99         int overwrite = 0;
 100         size_t length = iov_iter_count(from);
 101         ssize_t ret;
 102         loff_t pos = iocb->ki_pos;
 103
 104         /*
 105          * Unaligned direct AIO must be serialized; see comment above
 106          * In the case of O_APPEND, assume that we must always serialize
 107          */
 108         if (o_direct &&
 109             ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
 110             !is_sync_kiocb(iocb) &&
 111             (file->f_flags & O_APPEND ||
 112              ext4_unaligned_aio(inode, from, pos))) {
 113                 aio_mutex = ext4_aio_mutex(inode);
 114                 mutex_lock(aio_mutex);
 115                 ext4_unwritten_wait(inode);
 116         }
 117
 118         mutex_lock(&inode->i_mutex);
 119         if (file->f_flags & O_APPEND)
 120                 iocb->ki_pos = pos = i_size_read(inode);
 121
 122         /*
 123          * If we have encountered a bitmap-format file, the size limit
 124          * is smaller than s_maxbytes, which is for extent-mapped files.
 125          */
 126         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 127                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 128
 129                 if ((pos > sbi->s_bitmap_maxbytes) ||
 130                     (pos == sbi->s_bitmap_maxbytes && length > 0)) {
 131                         mutex_unlock(&inode->i_mutex);
 132                         ret = -EFBIG;
 133                         goto errout;
 134                 }
 135
 136                 if (pos + length > sbi->s_bitmap_maxbytes)
 137                         iov_iter_truncate(from, sbi->s_bitmap_maxbytes - pos);
 138         }
 139
 140         iocb->private = &overwrite;
 141         if (o_direct) {
 142                 blk_start_plug(&plug);
 143
 144
 145                 /* check whether we do a DIO overwrite or not */
 146                 if (ext4_should_dioread_nolock(inode) && !aio_mutex &&
 147                     !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
 148                         struct ext4_map_blocks map;
 149                         unsigned int blkbits = inode->i_blkbits;
 150                         int err, len;
 151
 152                         map.m_lblk = pos >> blkbits;
 153                         map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
 154                                 - map.m_lblk;
 155                         len = map.m_len;
 156
 157                         err = ext4_map_blocks(NULL, inode, &map, 0);
 158                         /*
 159                          * 'err==len' means that all of blocks has
 160                          * been preallocated no matter they are
 161                          * initialized or not.  For excluding
 162                          * unwritten extents, we need to check
 163                          * m_flags.  There are two conditions that
 164                          * indicate for initialized extents.  1) If we
 165                          * hit extent cache, EXT4_MAP_MAPPED flag is
 166                          * returned; 2) If we do a real lookup,
 167                          * non-flags are returned.  So we should check
 168                          * these two conditions.
 169                          */
 170                         if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
 171                                 overwrite = 1;
 172                 }
 173         }
 174
 175         ret = __generic_file_write_iter(iocb, from);
 176         mutex_unlock(&inode->i_mutex);
 177
 178         if (ret > 0) {
 179                 ssize_t err;
 180
 181                 err = generic_write_sync(file, iocb->ki_pos - ret, ret);
 182                 if (err < 0)
 183                         ret = err;
 184         }
 185         if (o_direct)
 186                 blk_finish_plug(&plug);
 187
 188 errout:
 189         if (aio_mutex)
 190                 mutex_unlock(aio_mutex);
 191         return ret;
 192 }
 193
 194 static const struct vm_operations_struct ext4_file_vm_ops = {
 195         .fault          = filemap_fault,
 196         .map_pages      = filemap_map_pages,
 197         .page_mkwrite   = ext4_page_mkwrite,
 198 };
 199
 200 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 201 {
 202         file_accessed(file);
 203         vma->vm_ops = &ext4_file_vm_ops;
 204         return 0;
 205 }
 206
 207 static int ext4_file_open(struct inode * inode, struct file * filp)
 208 {
 209         struct super_block *sb = inode->i_sb;
 210         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 211         struct vfsmount *mnt = filp->f_path.mnt;
 212         struct path path;
 213         char buf[64], *cp;
 214
 215         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 216                      !(sb->s_flags & MS_RDONLY))) {
 217                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 218                 /*
 219                  * Sample where the filesystem has been mounted and
 220                  * store it in the superblock for sysadmin convenience
 221                  * when trying to sort through large numbers of block
 222                  * devices or filesystem images.
 223                  */
 224                 memset(buf, 0, sizeof(buf));
 225                 path.mnt = mnt;
 226                 path.dentry = mnt->mnt_root;
 227                 cp = d_path(&path, buf, sizeof(buf));
 228                 if (!IS_ERR(cp)) {
 229                         handle_t *handle;
 230                         int err;
 231
 232                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 233                         if (IS_ERR(handle))
 234                                 return PTR_ERR(handle);
 235                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 236                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 237                         if (err) {
 238                                 ext4_journal_stop(handle);
 239                                 return err;
 240                         }
 241                         strlcpy(sbi->s_es->s_last_mounted, cp,
 242                                 sizeof(sbi->s_es->s_last_mounted));
 243                         ext4_handle_dirty_super(handle, sb);
 244                         ext4_journal_stop(handle);
 245                 }
 246         }
 247         /*
 248          * Set up the jbd2_inode if we are opening the inode for
 249          * writing and the journal is present
 250          */
 251         if (filp->f_mode & FMODE_WRITE) {
 252                 int ret = ext4_inode_attach_jinode(inode);
 253                 if (ret < 0)
 254                         return ret;
 255         }
 256         return dquot_file_open(inode, filp);
 257 }
 258
 259 /*
 260  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 261  * file rather than ext4_ext_walk_space() because we can introduce
 262  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 263  * function.  When extent status tree has been fully implemented, it will
 264  * track all extent status for a file and we can directly use it to
 265  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 266  */
 267
 268 /*
 269  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 270  * lookup page cache to check whether or not there has some data between
 271  * [startoff, endoff] because, if this range contains an unwritten extent,
 272  * we determine this extent as a data or a hole according to whether the
 273  * page cache has data or not.
 274  */
 275 static int ext4_find_unwritten_pgoff(struct inode *inode,
 276                                      int whence,
 277                                      struct ext4_map_blocks *map,
 278                                      loff_t *offset)
 279 {
 280         struct pagevec pvec;
 281         unsigned int blkbits;
 282         pgoff_t index;
 283         pgoff_t end;
 284         loff_t endoff;
 285         loff_t startoff;
 286         loff_t lastoff;
 287         int found = 0;
 288
 289         blkbits = inode->i_sb->s_blocksize_bits;
 290         startoff = *offset;
 291         lastoff = startoff;
 292         endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
 293
 294         index = startoff >> PAGE_CACHE_SHIFT;
 295         end = endoff >> PAGE_CACHE_SHIFT;
 296
 297         pagevec_init(&pvec, 0);
 298         do {
 299                 int i, num;
 300                 unsigned long nr_pages;
 301
 302                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
 303                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 304                                           (pgoff_t)num);
 305                 if (nr_pages == 0) {
 306                         if (whence == SEEK_DATA)
 307                                 break;
 308
 309                         BUG_ON(whence != SEEK_HOLE);
 310                         /*
 311                          * If this is the first time to go into the loop and
 312                          * offset is not beyond the end offset, it will be a
 313                          * hole at this offset
 314                          */
 315                         if (lastoff == startoff || lastoff < endoff)
 316                                 found = 1;
 317                         break;
 318                 }
 319
 320                 /*
 321                  * If this is the first time to go into the loop and
 322                  * offset is smaller than the first page offset, it will be a
 323                  * hole at this offset.
 324                  */
 325                 if (lastoff == startoff && whence == SEEK_HOLE &&
 326                     lastoff < page_offset(pvec.pages[0])) {
 327                         found = 1;
 328                         break;
 329                 }
 330
 331                 for (i = 0; i < nr_pages; i++) {
 332                         struct page *page = pvec.pages[i];
 333                         struct buffer_head *bh, *head;
 334
 335                         /*
 336                          * If the current offset is not beyond the end of given
 337                          * range, it will be a hole.
 338                          */
 339                         if (lastoff < endoff && whence == SEEK_HOLE &&
 340                             page->index > end) {
 341                                 found = 1;
 342                                 *offset = lastoff;
 343                                 goto out;
 344                         }
 345
 346                         lock_page(page);
 347
 348                         if (unlikely(page->mapping != inode->i_mapping)) {
 349                                 unlock_page(page);
 350                                 continue;
 351                         }
 352
 353                         if (!page_has_buffers(page)) {
 354                                 unlock_page(page);
 355                                 continue;
 356                         }
 357
 358                         if (page_has_buffers(page)) {
 359                                 lastoff = page_offset(page);
 360                                 bh = head = page_buffers(page);
 361                                 do {
 362                                         if (buffer_uptodate(bh) ||
 363                                             buffer_unwritten(bh)) {
 364                                                 if (whence == SEEK_DATA)
 365                                                         found = 1;
 366                                         } else {
 367                                                 if (whence == SEEK_HOLE)
 368                                                         found = 1;
 369                                         }
 370                                         if (found) {
 371                                                 *offset = max_t(loff_t,
 372                                                         startoff, lastoff);
 373                                                 unlock_page(page);
 374                                                 goto out;
 375                                         }
 376                                         lastoff += bh->b_size;
 377                                         bh = bh->b_this_page;
 378                                 } while (bh != head);
 379                         }
 380
 381                         lastoff = page_offset(page) + PAGE_SIZE;
 382                         unlock_page(page);
 383                 }
 384
 385                 /*
 386                  * The no. of pages is less than our desired, that would be a
 387                  * hole in there.
 388                  */
 389                 if (nr_pages < num && whence == SEEK_HOLE) {
 390                         found = 1;
 391                         *offset = lastoff;
 392                         break;
 393                 }
 394
 395                 index = pvec.pages[i - 1]->index + 1;
 396                 pagevec_release(&pvec);
 397         } while (index <= end);
 398
 399 out:
 400         pagevec_release(&pvec);
 401         return found;
 402 }
 403
 404 /*
 405  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 406  */
 407 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 408 {
 409         struct inode *inode = file->f_mapping->host;
 410         struct ext4_map_blocks map;
 411         struct extent_status es;
 412         ext4_lblk_t start, last, end;
 413         loff_t dataoff, isize;
 414         int blkbits;
 415         int ret = 0;
 416
 417         mutex_lock(&inode->i_mutex);
 418
 419         isize = i_size_read(inode);
 420         if (offset >= isize) {
 421                 mutex_unlock(&inode->i_mutex);
 422                 return -ENXIO;
 423         }
 424
 425         blkbits = inode->i_sb->s_blocksize_bits;
 426         start = offset >> blkbits;
 427         last = start;
 428         end = isize >> blkbits;
 429         dataoff = offset;
 430
 431         do {
 432                 map.m_lblk = last;
 433                 map.m_len = end - last + 1;
 434                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 435                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 436                         if (last != start)
 437                                 dataoff = (loff_t)last << blkbits;
 438                         break;
 439                 }
 440
 441                 /*
 442                  * If there is a delay extent at this offset,
 443                  * it will be as a data.
 444                  */
 445                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 446                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 447                         if (last != start)
 448                                 dataoff = (loff_t)last << blkbits;
 449                         break;
 450                 }
 451
 452                 /*
 453                  * If there is a unwritten extent at this offset,
 454                  * it will be as a data or a hole according to page
 455                  * cache that has data or not.
 456                  */
 457                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 458                         int unwritten;
 459                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 460                                                               &map, &dataoff);
 461                         if (unwritten)
 462                                 break;
 463                 }
 464
 465                 last++;
 466                 dataoff = (loff_t)last << blkbits;
 467         } while (last <= end);
 468
 469         mutex_unlock(&inode->i_mutex);
 470
 471         if (dataoff > isize)
 472                 return -ENXIO;
 473
 474         return vfs_setpos(file, dataoff, maxsize);
 475 }
 476
 477 /*
 478  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 479  */
 480 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 481 {
 482         struct inode *inode = file->f_mapping->host;
 483         struct ext4_map_blocks map;
 484         struct extent_status es;
 485         ext4_lblk_t start, last, end;
 486         loff_t holeoff, isize;
 487         int blkbits;
 488         int ret = 0;
 489
 490         mutex_lock(&inode->i_mutex);
 491
 492         isize = i_size_read(inode);
 493         if (offset >= isize) {
 494                 mutex_unlock(&inode->i_mutex);
 495                 return -ENXIO;
 496         }
 497
 498         blkbits = inode->i_sb->s_blocksize_bits;
 499         start = offset >> blkbits;
 500         last = start;
 501         end = isize >> blkbits;
 502         holeoff = offset;
 503
 504         do {
 505                 map.m_lblk = last;
 506                 map.m_len = end - last + 1;
 507                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 508                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 509                         last += ret;
 510                         holeoff = (loff_t)last << blkbits;
 511                         continue;
 512                 }
 513
 514                 /*
 515                  * If there is a delay extent at this offset,
 516                  * we will skip this extent.
 517                  */
 518                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 519                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 520                         last = es.es_lblk + es.es_len;
 521                         holeoff = (loff_t)last << blkbits;
 522                         continue;
 523                 }
 524
 525                 /*
 526                  * If there is a unwritten extent at this offset,
 527                  * it will be as a data or a hole according to page
 528                  * cache that has data or not.
 529                  */
 530                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 531                         int unwritten;
 532                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 533                                                               &map, &holeoff);
 534                         if (!unwritten) {
 535                                 last += ret;
 536                                 holeoff = (loff_t)last << blkbits;
 537                                 continue;
 538                         }
 539                 }
 540
 541                 /* find a hole */
 542                 break;
 543         } while (last <= end);
 544
 545         mutex_unlock(&inode->i_mutex);
 546
 547         if (holeoff > isize)
 548                 holeoff = isize;
 549
 550         return vfs_setpos(file, holeoff, maxsize);
 551 }
 552
 553 /*
 554  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 555  * by calling generic_file_llseek_size() with the appropriate maxbytes
 556  * value for each.
 557  */
 558 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 559 {
 560         struct inode *inode = file->f_mapping->host;
 561         loff_t maxbytes;
 562
 563         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 564                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 565         else
 566                 maxbytes = inode->i_sb->s_maxbytes;
 567
 568         switch (whence) {
 569         case SEEK_SET:
 570         case SEEK_CUR:
 571         case SEEK_END:
 572                 return generic_file_llseek_size(file, offset, whence,
 573                                                 maxbytes, i_size_read(inode));
 574         case SEEK_DATA:
 575                 return ext4_seek_data(file, offset, maxbytes);
 576         case SEEK_HOLE:
 577                 return ext4_seek_hole(file, offset, maxbytes);
 578         }
 579
 580         return -EINVAL;
 581 }
 582
 583 const struct file_operations ext4_file_operations = {
 584         .llseek         = ext4_llseek,
 585         .read           = new_sync_read,
 586         .write          = new_sync_write,
 587         .read_iter      = generic_file_read_iter,
 588         .write_iter     = ext4_file_write_iter,
 589         .unlocked_ioctl = ext4_ioctl,
 590 #ifdef CONFIG_COMPAT
 591         .compat_ioctl   = ext4_compat_ioctl,
 592 #endif
 593         .mmap           = ext4_file_mmap,
 594         .open           = ext4_file_open,
 595         .release        = ext4_release_file,
 596         .fsync          = ext4_sync_file,
 597         .splice_read    = generic_file_splice_read,
 598         .splice_write   = iter_file_splice_write,
 599         .fallocate      = ext4_fallocate,
 600 };
 601
 602 const struct inode_operations ext4_file_inode_operations = {
 603         .setattr        = ext4_setattr,
 604         .getattr        = ext4_getattr,
 605         .setxattr       = generic_setxattr,
 606         .getxattr       = generic_getxattr,
 607         .listxattr      = ext4_listxattr,
 608         .removexattr    = generic_removexattr,
 609         .get_acl        = ext4_get_acl,
 610         .set_acl        = ext4_set_acl,
 611         .fiemap         = ext4_fiemap,
 612 };
 613