fs/ext4/file.c

   1 /*
   2  *  linux/fs/ext4/file.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card ([email protected])
   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  *      ([email protected])
  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/quotaops.h>
  27 #include <linux/pagevec.h>
  28 #include "ext4.h"
  29 #include "ext4_jbd2.h"
  30 #include "xattr.h"
  31 #include "acl.h"
  32
  33 /*
  34  * Called when an inode is released. Note that this is different
  35  * from ext4_file_open: open gets called at every open, but release
  36  * gets called only when /all/ the files are closed.
  37  */
  38 static int ext4_release_file(struct inode *inode, struct file *filp)
  39 {
  40         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
  41                 ext4_alloc_da_blocks(inode);
  42                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
  43         }
  44         /* if we are the last writer on the inode, drop the block reservation */
  45         if ((filp->f_mode & FMODE_WRITE) &&
  46                         (atomic_read(&inode->i_writecount) == 1) &&
  47                         !EXT4_I(inode)->i_reserved_data_blocks)
  48         {
  49                 down_write(&EXT4_I(inode)->i_data_sem);
  50                 ext4_discard_preallocations(inode);
  51                 up_write(&EXT4_I(inode)->i_data_sem);
  52         }
  53         if (is_dx(inode) && filp->private_data)
  54                 ext4_htree_free_dir_info(filp->private_data);
  55
  56         return 0;
  57 }
  58
  59 void ext4_unwritten_wait(struct inode *inode)
  60 {
  61         wait_queue_head_t *wq = ext4_ioend_wq(inode);
  62
  63         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
  64 }
  65
  66 /*
  67  * This tests whether the IO in question is block-aligned or not.
  68  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
  69  * are converted to written only after the IO is complete.  Until they are
  70  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
  71  * it needs to zero out portions of the start and/or end block.  If 2 AIO
  72  * threads are at work on the same unwritten block, they must be synchronized
  73  * or one thread will zero the other's data, causing corruption.
  74  */
  75 static int
  76 ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
  77                    unsigned long nr_segs, loff_t pos)
  78 {
  79         struct super_block *sb = inode->i_sb;
  80         int blockmask = sb->s_blocksize - 1;
  81         size_t count = iov_length(iov, nr_segs);
  82         loff_t final_size = pos + count;
  83
  84         if (pos >= inode->i_size)
  85                 return 0;
  86
  87         if ((pos & blockmask) || (final_size & blockmask))
  88                 return 1;
  89
  90         return 0;
  91 }
  92
  93 static ssize_t
  94 ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov,
  95                     unsigned long nr_segs, loff_t pos)
  96 {
  97         struct file *file = iocb->ki_filp;
  98         struct inode *inode = file->f_mapping->host;
  99         struct blk_plug plug;
 100         int unaligned_aio = 0;
 101         ssize_t ret;
 102         int overwrite = 0;
 103         size_t length = iov_length(iov, nr_segs);
 104
 105         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
 106             !is_sync_kiocb(iocb))
 107                 unaligned_aio = ext4_unaligned_aio(inode, iov, nr_segs, pos);
 108
 109         /* Unaligned direct AIO must be serialized; see comment above */
 110         if (unaligned_aio) {
 111                 mutex_lock(ext4_aio_mutex(inode));
 112                 ext4_unwritten_wait(inode);
 113         }
 114
 115         BUG_ON(iocb->ki_pos != pos);
 116
 117         mutex_lock(&inode->i_mutex);
 118         blk_start_plug(&plug);
 119
 120         iocb->private = &overwrite;
 121
 122         /* check whether we do a DIO overwrite or not */
 123         if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
 124             !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
 125                 struct ext4_map_blocks map;
 126                 unsigned int blkbits = inode->i_blkbits;
 127                 int err, len;
 128
 129                 map.m_lblk = pos >> blkbits;
 130                 map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
 131                         - map.m_lblk;
 132                 len = map.m_len;
 133
 134                 err = ext4_map_blocks(NULL, inode, &map, 0);
 135                 /*
 136                  * 'err==len' means that all of blocks has been preallocated no
 137                  * matter they are initialized or not.  For excluding
 138                  * uninitialized extents, we need to check m_flags.  There are
 139                  * two conditions that indicate for initialized extents.
 140                  * 1) If we hit extent cache, EXT4_MAP_MAPPED flag is returned;
 141                  * 2) If we do a real lookup, non-flags are returned.
 142                  * So we should check these two conditions.
 143                  */
 144                 if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
 145                         overwrite = 1;
 146         }
 147
 148         ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 149         mutex_unlock(&inode->i_mutex);
 150
 151         if (ret > 0 || ret == -EIOCBQUEUED) {
 152                 ssize_t err;
 153
 154                 err = generic_write_sync(file, pos, ret);
 155                 if (err < 0 && ret > 0)
 156                         ret = err;
 157         }
 158         blk_finish_plug(&plug);
 159
 160         if (unaligned_aio)
 161                 mutex_unlock(ext4_aio_mutex(inode));
 162
 163         return ret;
 164 }
 165
 166 static ssize_t
 167 ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 168                 unsigned long nr_segs, loff_t pos)
 169 {
 170         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
 171         ssize_t ret;
 172
 173         /*
 174          * If we have encountered a bitmap-format file, the size limit
 175          * is smaller than s_maxbytes, which is for extent-mapped files.
 176          */
 177
 178         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 179                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 180                 size_t length = iov_length(iov, nr_segs);
 181
 182                 if ((pos > sbi->s_bitmap_maxbytes ||
 183                     (pos == sbi->s_bitmap_maxbytes && length > 0)))
 184                         return -EFBIG;
 185
 186                 if (pos + length > sbi->s_bitmap_maxbytes) {
 187                         nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
 188                                               sbi->s_bitmap_maxbytes - pos);
 189                 }
 190         }
 191
 192         if (unlikely(iocb->ki_filp->f_flags & O_DIRECT))
 193                 ret = ext4_file_dio_write(iocb, iov, nr_segs, pos);
 194         else
 195                 ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
 196
 197         return ret;
 198 }
 199
 200 static const struct vm_operations_struct ext4_file_vm_ops = {
 201         .fault          = filemap_fault,
 202         .page_mkwrite   = ext4_page_mkwrite,
 203         .remap_pages    = generic_file_remap_pages,
 204 };
 205
 206 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 207 {
 208         struct address_space *mapping = file->f_mapping;
 209
 210         if (!mapping->a_ops->readpage)
 211                 return -ENOEXEC;
 212         file_accessed(file);
 213         vma->vm_ops = &ext4_file_vm_ops;
 214         return 0;
 215 }
 216
 217 static int ext4_file_open(struct inode * inode, struct file * filp)
 218 {
 219         struct super_block *sb = inode->i_sb;
 220         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 221         struct ext4_inode_info *ei = EXT4_I(inode);
 222         struct vfsmount *mnt = filp->f_path.mnt;
 223         struct path path;
 224         char buf[64], *cp;
 225
 226         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 227                      !(sb->s_flags & MS_RDONLY))) {
 228                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 229                 /*
 230                  * Sample where the filesystem has been mounted and
 231                  * store it in the superblock for sysadmin convenience
 232                  * when trying to sort through large numbers of block
 233                  * devices or filesystem images.
 234                  */
 235                 memset(buf, 0, sizeof(buf));
 236                 path.mnt = mnt;
 237                 path.dentry = mnt->mnt_root;
 238                 cp = d_path(&path, buf, sizeof(buf));
 239                 if (!IS_ERR(cp)) {
 240                         handle_t *handle;
 241                         int err;
 242
 243                         handle = ext4_journal_start_sb(sb, 1);
 244                         if (IS_ERR(handle))
 245                                 return PTR_ERR(handle);
 246                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 247                         if (err) {
 248                                 ext4_journal_stop(handle);
 249                                 return err;
 250                         }
 251                         strlcpy(sbi->s_es->s_last_mounted, cp,
 252                                 sizeof(sbi->s_es->s_last_mounted));
 253                         ext4_handle_dirty_super(handle, sb);
 254                         ext4_journal_stop(handle);
 255                 }
 256         }
 257         /*
 258          * Set up the jbd2_inode if we are opening the inode for
 259          * writing and the journal is present
 260          */
 261         if (sbi->s_journal && !ei->jinode && (filp->f_mode & FMODE_WRITE)) {
 262                 struct jbd2_inode *jinode = jbd2_alloc_inode(GFP_KERNEL);
 263
 264                 spin_lock(&inode->i_lock);
 265                 if (!ei->jinode) {
 266                         if (!jinode) {
 267                                 spin_unlock(&inode->i_lock);
 268                                 return -ENOMEM;
 269                         }
 270                         ei->jinode = jinode;
 271                         jbd2_journal_init_jbd_inode(ei->jinode, inode);
 272                         jinode = NULL;
 273                 }
 274                 spin_unlock(&inode->i_lock);
 275                 if (unlikely(jinode != NULL))
 276                         jbd2_free_inode(jinode);
 277         }
 278         return dquot_file_open(inode, filp);
 279 }
 280
 281 /*
 282  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 283  * file rather than ext4_ext_walk_space() because we can introduce
 284  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 285  * function.  When extent status tree has been fully implemented, it will
 286  * track all extent status for a file and we can directly use it to
 287  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 288  */
 289
 290 /*
 291  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 292  * lookup page cache to check whether or not there has some data between
 293  * [startoff, endoff] because, if this range contains an unwritten extent,
 294  * we determine this extent as a data or a hole according to whether the
 295  * page cache has data or not.
 296  */
 297 static int ext4_find_unwritten_pgoff(struct inode *inode,
 298                                      int whence,
 299                                      struct ext4_map_blocks *map,
 300                                      loff_t *offset)
 301 {
 302         struct pagevec pvec;
 303         unsigned int blkbits;
 304         pgoff_t index;
 305         pgoff_t end;
 306         loff_t endoff;
 307         loff_t startoff;
 308         loff_t lastoff;
 309         int found = 0;
 310
 311         blkbits = inode->i_sb->s_blocksize_bits;
 312         startoff = *offset;
 313         lastoff = startoff;
 314         endoff = (map->m_lblk + map->m_len) << blkbits;
 315
 316         index = startoff >> PAGE_CACHE_SHIFT;
 317         end = endoff >> PAGE_CACHE_SHIFT;
 318
 319         pagevec_init(&pvec, 0);
 320         do {
 321                 int i, num;
 322                 unsigned long nr_pages;
 323
 324                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
 325                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 326                                           (pgoff_t)num);
 327                 if (nr_pages == 0) {
 328                         if (whence == SEEK_DATA)
 329                                 break;
 330
 331                         BUG_ON(whence != SEEK_HOLE);
 332                         /*
 333                          * If this is the first time to go into the loop and
 334                          * offset is not beyond the end offset, it will be a
 335                          * hole at this offset
 336                          */
 337                         if (lastoff == startoff || lastoff < endoff)
 338                                 found = 1;
 339                         break;
 340                 }
 341
 342                 /*
 343                  * If this is the first time to go into the loop and
 344                  * offset is smaller than the first page offset, it will be a
 345                  * hole at this offset.
 346                  */
 347                 if (lastoff == startoff && whence == SEEK_HOLE &&
 348                     lastoff < page_offset(pvec.pages[0])) {
 349                         found = 1;
 350                         break;
 351                 }
 352
 353                 for (i = 0; i < nr_pages; i++) {
 354                         struct page *page = pvec.pages[i];
 355                         struct buffer_head *bh, *head;
 356
 357                         /*
 358                          * If the current offset is not beyond the end of given
 359                          * range, it will be a hole.
 360                          */
 361                         if (lastoff < endoff && whence == SEEK_HOLE &&
 362                             page->index > end) {
 363                                 found = 1;
 364                                 *offset = lastoff;
 365                                 goto out;
 366                         }
 367
 368                         lock_page(page);
 369
 370                         if (unlikely(page->mapping != inode->i_mapping)) {
 371                                 unlock_page(page);
 372                                 continue;
 373                         }
 374
 375                         if (!page_has_buffers(page)) {
 376                                 unlock_page(page);
 377                                 continue;
 378                         }
 379
 380                         if (page_has_buffers(page)) {
 381                                 lastoff = page_offset(page);
 382                                 bh = head = page_buffers(page);
 383                                 do {
 384                                         if (buffer_uptodate(bh) ||
 385                                             buffer_unwritten(bh)) {
 386                                                 if (whence == SEEK_DATA)
 387                                                         found = 1;
 388                                         } else {
 389                                                 if (whence == SEEK_HOLE)
 390                                                         found = 1;
 391                                         }
 392                                         if (found) {
 393                                                 *offset = max_t(loff_t,
 394                                                         startoff, lastoff);
 395                                                 unlock_page(page);
 396                                                 goto out;
 397                                         }
 398                                         lastoff += bh->b_size;
 399                                         bh = bh->b_this_page;
 400                                 } while (bh != head);
 401                         }
 402
 403                         lastoff = page_offset(page) + PAGE_SIZE;
 404                         unlock_page(page);
 405                 }
 406
 407                 /*
 408                  * The no. of pages is less than our desired, that would be a
 409                  * hole in there.
 410                  */
 411                 if (nr_pages < num && whence == SEEK_HOLE) {
 412                         found = 1;
 413                         *offset = lastoff;
 414                         break;
 415                 }
 416
 417                 index = pvec.pages[i - 1]->index + 1;
 418                 pagevec_release(&pvec);
 419         } while (index <= end);
 420
 421 out:
 422         pagevec_release(&pvec);
 423         return found;
 424 }
 425
 426 /*
 427  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 428  */
 429 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 430 {
 431         struct inode *inode = file->f_mapping->host;
 432         struct ext4_map_blocks map;
 433         struct extent_status es;
 434         ext4_lblk_t start, last, end;
 435         loff_t dataoff, isize;
 436         int blkbits;
 437         int ret = 0;
 438
 439         mutex_lock(&inode->i_mutex);
 440
 441         isize = i_size_read(inode);
 442         if (offset >= isize) {
 443                 mutex_unlock(&inode->i_mutex);
 444                 return -ENXIO;
 445         }
 446
 447         blkbits = inode->i_sb->s_blocksize_bits;
 448         start = offset >> blkbits;
 449         last = start;
 450         end = isize >> blkbits;
 451         dataoff = offset;
 452
 453         do {
 454                 map.m_lblk = last;
 455                 map.m_len = end - last + 1;
 456                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 457                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 458                         if (last != start)
 459                                 dataoff = last << blkbits;
 460                         break;
 461                 }
 462
 463                 /*
 464                  * If there is a delay extent at this offset,
 465                  * it will be as a data.
 466                  */
 467                 es.start = last;
 468                 (void)ext4_es_find_extent(inode, &es);
 469                 if (last >= es.start &&
 470                     last < es.start + es.len) {
 471                         if (last != start)
 472                                 dataoff = last << blkbits;
 473                         break;
 474                 }
 475
 476                 /*
 477                  * If there is a unwritten extent at this offset,
 478                  * it will be as a data or a hole according to page
 479                  * cache that has data or not.
 480                  */
 481                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 482                         int unwritten;
 483                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 484                                                               &map, &dataoff);
 485                         if (unwritten)
 486                                 break;
 487                 }
 488
 489                 last++;
 490                 dataoff = last << blkbits;
 491         } while (last <= end);
 492
 493         mutex_unlock(&inode->i_mutex);
 494
 495         if (dataoff > isize)
 496                 return -ENXIO;
 497
 498         if (dataoff < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
 499                 return -EINVAL;
 500         if (dataoff > maxsize)
 501                 return -EINVAL;
 502
 503         if (dataoff != file->f_pos) {
 504                 file->f_pos = dataoff;
 505                 file->f_version = 0;
 506         }
 507
 508         return dataoff;
 509 }
 510
 511 /*
 512  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 513  */
 514 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 515 {
 516         struct inode *inode = file->f_mapping->host;
 517         struct ext4_map_blocks map;
 518         struct extent_status es;
 519         ext4_lblk_t start, last, end;
 520         loff_t holeoff, isize;
 521         int blkbits;
 522         int ret = 0;
 523
 524         mutex_lock(&inode->i_mutex);
 525
 526         isize = i_size_read(inode);
 527         if (offset >= isize) {
 528                 mutex_unlock(&inode->i_mutex);
 529                 return -ENXIO;
 530         }
 531
 532         blkbits = inode->i_sb->s_blocksize_bits;
 533         start = offset >> blkbits;
 534         last = start;
 535         end = isize >> blkbits;
 536         holeoff = offset;
 537
 538         do {
 539                 map.m_lblk = last;
 540                 map.m_len = end - last + 1;
 541                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 542                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 543                         last += ret;
 544                         holeoff = last << blkbits;
 545                         continue;
 546                 }
 547
 548                 /*
 549                  * If there is a delay extent at this offset,
 550                  * we will skip this extent.
 551                  */
 552                 es.start = last;
 553                 (void)ext4_es_find_extent(inode, &es);
 554                 if (last >= es.start &&
 555                     last < es.start + es.len) {
 556                         last = es.start + es.len;
 557                         holeoff = last << blkbits;
 558                         continue;
 559                 }
 560
 561                 /*
 562                  * If there is a unwritten extent at this offset,
 563                  * it will be as a data or a hole according to page
 564                  * cache that has data or not.
 565                  */
 566                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 567                         int unwritten;
 568                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 569                                                               &map, &holeoff);
 570                         if (!unwritten) {
 571                                 last += ret;
 572                                 holeoff = last << blkbits;
 573                                 continue;
 574                         }
 575                 }
 576
 577                 /* find a hole */
 578                 break;
 579         } while (last <= end);
 580
 581         mutex_unlock(&inode->i_mutex);
 582
 583         if (holeoff > isize)
 584                 holeoff = isize;
 585
 586         if (holeoff < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
 587                 return -EINVAL;
 588         if (holeoff > maxsize)
 589                 return -EINVAL;
 590
 591         if (holeoff != file->f_pos) {
 592                 file->f_pos = holeoff;
 593                 file->f_version = 0;
 594         }
 595
 596         return holeoff;
 597 }
 598
 599 /*
 600  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 601  * by calling generic_file_llseek_size() with the appropriate maxbytes
 602  * value for each.
 603  */
 604 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 605 {
 606         struct inode *inode = file->f_mapping->host;
 607         loff_t maxbytes;
 608
 609         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 610                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 611         else
 612                 maxbytes = inode->i_sb->s_maxbytes;
 613
 614         switch (whence) {
 615         case SEEK_SET:
 616         case SEEK_CUR:
 617         case SEEK_END:
 618                 return generic_file_llseek_size(file, offset, whence,
 619                                                 maxbytes, i_size_read(inode));
 620         case SEEK_DATA:
 621                 return ext4_seek_data(file, offset, maxbytes);
 622         case SEEK_HOLE:
 623                 return ext4_seek_hole(file, offset, maxbytes);
 624         }
 625
 626         return -EINVAL;
 627 }
 628
 629 const struct file_operations ext4_file_operations = {
 630         .llseek         = ext4_llseek,
 631         .read           = do_sync_read,
 632         .write          = do_sync_write,
 633         .aio_read       = generic_file_aio_read,
 634         .aio_write      = ext4_file_write,
 635         .unlocked_ioctl = ext4_ioctl,
 636 #ifdef CONFIG_COMPAT
 637         .compat_ioctl   = ext4_compat_ioctl,
 638 #endif
 639         .mmap           = ext4_file_mmap,
 640         .open           = ext4_file_open,
 641         .release        = ext4_release_file,
 642         .fsync          = ext4_sync_file,
 643         .splice_read    = generic_file_splice_read,
 644         .splice_write   = generic_file_splice_write,
 645         .fallocate      = ext4_fallocate,
 646 };
 647
 648 const struct inode_operations ext4_file_inode_operations = {
 649         .setattr        = ext4_setattr,
 650         .getattr        = ext4_getattr,
 651         .setxattr       = generic_setxattr,
 652         .getxattr       = generic_getxattr,
 653         .listxattr      = ext4_listxattr,
 654         .removexattr    = generic_removexattr,
 655         .get_acl        = ext4_get_acl,
 656         .fiemap         = ext4_fiemap,
 657 };
 658