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/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 = io_is_direct(file);
  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 #ifdef CONFIG_FS_DAX
 195 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 196 {
 197         return dax_fault(vma, vmf, ext4_get_block);
 198                                         /* Is this the right get_block? */
 199 }
 200
 201 static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 202 {
 203         return dax_mkwrite(vma, vmf, ext4_get_block);
 204 }
 205
 206 static const struct vm_operations_struct ext4_dax_vm_ops = {
 207         .fault          = ext4_dax_fault,
 208         .page_mkwrite   = ext4_dax_mkwrite,
 209 };
 210 #else
 211 #define ext4_dax_vm_ops ext4_file_vm_ops
 212 #endif
 213
 214 static const struct vm_operations_struct ext4_file_vm_ops = {
 215         .fault          = filemap_fault,
 216         .map_pages      = filemap_map_pages,
 217         .page_mkwrite   = ext4_page_mkwrite,
 218 };
 219
 220 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 221 {
 222         file_accessed(file);
 223         if (IS_DAX(file_inode(file))) {
 224                 vma->vm_ops = &ext4_dax_vm_ops;
 225                 vma->vm_flags |= VM_MIXEDMAP;
 226         } else {
 227                 vma->vm_ops = &ext4_file_vm_ops;
 228         }
 229         return 0;
 230 }
 231
 232 static int ext4_file_open(struct inode * inode, struct file * filp)
 233 {
 234         struct super_block *sb = inode->i_sb;
 235         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 236         struct vfsmount *mnt = filp->f_path.mnt;
 237         struct path path;
 238         char buf[64], *cp;
 239
 240         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 241                      !(sb->s_flags & MS_RDONLY))) {
 242                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 243                 /*
 244                  * Sample where the filesystem has been mounted and
 245                  * store it in the superblock for sysadmin convenience
 246                  * when trying to sort through large numbers of block
 247                  * devices or filesystem images.
 248                  */
 249                 memset(buf, 0, sizeof(buf));
 250                 path.mnt = mnt;
 251                 path.dentry = mnt->mnt_root;
 252                 cp = d_path(&path, buf, sizeof(buf));
 253                 if (!IS_ERR(cp)) {
 254                         handle_t *handle;
 255                         int err;
 256
 257                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 258                         if (IS_ERR(handle))
 259                                 return PTR_ERR(handle);
 260                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 261                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 262                         if (err) {
 263                                 ext4_journal_stop(handle);
 264                                 return err;
 265                         }
 266                         strlcpy(sbi->s_es->s_last_mounted, cp,
 267                                 sizeof(sbi->s_es->s_last_mounted));
 268                         ext4_handle_dirty_super(handle, sb);
 269                         ext4_journal_stop(handle);
 270                 }
 271         }
 272         /*
 273          * Set up the jbd2_inode if we are opening the inode for
 274          * writing and the journal is present
 275          */
 276         if (filp->f_mode & FMODE_WRITE) {
 277                 int ret = ext4_inode_attach_jinode(inode);
 278                 if (ret < 0)
 279                         return ret;
 280         }
 281         return dquot_file_open(inode, filp);
 282 }
 283
 284 /*
 285  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 286  * file rather than ext4_ext_walk_space() because we can introduce
 287  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 288  * function.  When extent status tree has been fully implemented, it will
 289  * track all extent status for a file and we can directly use it to
 290  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 291  */
 292
 293 /*
 294  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 295  * lookup page cache to check whether or not there has some data between
 296  * [startoff, endoff] because, if this range contains an unwritten extent,
 297  * we determine this extent as a data or a hole according to whether the
 298  * page cache has data or not.
 299  */
 300 static int ext4_find_unwritten_pgoff(struct inode *inode,
 301                                      int whence,
 302                                      struct ext4_map_blocks *map,
 303                                      loff_t *offset)
 304 {
 305         struct pagevec pvec;
 306         unsigned int blkbits;
 307         pgoff_t index;
 308         pgoff_t end;
 309         loff_t endoff;
 310         loff_t startoff;
 311         loff_t lastoff;
 312         int found = 0;
 313
 314         blkbits = inode->i_sb->s_blocksize_bits;
 315         startoff = *offset;
 316         lastoff = startoff;
 317         endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
 318
 319         index = startoff >> PAGE_CACHE_SHIFT;
 320         end = endoff >> PAGE_CACHE_SHIFT;
 321
 322         pagevec_init(&pvec, 0);
 323         do {
 324                 int i, num;
 325                 unsigned long nr_pages;
 326
 327                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
 328                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 329                                           (pgoff_t)num);
 330                 if (nr_pages == 0) {
 331                         if (whence == SEEK_DATA)
 332                                 break;
 333
 334                         BUG_ON(whence != SEEK_HOLE);
 335                         /*
 336                          * If this is the first time to go into the loop and
 337                          * offset is not beyond the end offset, it will be a
 338                          * hole at this offset
 339                          */
 340                         if (lastoff == startoff || lastoff < endoff)
 341                                 found = 1;
 342                         break;
 343                 }
 344
 345                 /*
 346                  * If this is the first time to go into the loop and
 347                  * offset is smaller than the first page offset, it will be a
 348                  * hole at this offset.
 349                  */
 350                 if (lastoff == startoff && whence == SEEK_HOLE &&
 351                     lastoff < page_offset(pvec.pages[0])) {
 352                         found = 1;
 353                         break;
 354                 }
 355
 356                 for (i = 0; i < nr_pages; i++) {
 357                         struct page *page = pvec.pages[i];
 358                         struct buffer_head *bh, *head;
 359
 360                         /*
 361                          * If the current offset is not beyond the end of given
 362                          * range, it will be a hole.
 363                          */
 364                         if (lastoff < endoff && whence == SEEK_HOLE &&
 365                             page->index > end) {
 366                                 found = 1;
 367                                 *offset = lastoff;
 368                                 goto out;
 369                         }
 370
 371                         lock_page(page);
 372
 373                         if (unlikely(page->mapping != inode->i_mapping)) {
 374                                 unlock_page(page);
 375                                 continue;
 376                         }
 377
 378                         if (!page_has_buffers(page)) {
 379                                 unlock_page(page);
 380                                 continue;
 381                         }
 382
 383                         if (page_has_buffers(page)) {
 384                                 lastoff = page_offset(page);
 385                                 bh = head = page_buffers(page);
 386                                 do {
 387                                         if (buffer_uptodate(bh) ||
 388                                             buffer_unwritten(bh)) {
 389                                                 if (whence == SEEK_DATA)
 390                                                         found = 1;
 391                                         } else {
 392                                                 if (whence == SEEK_HOLE)
 393                                                         found = 1;
 394                                         }
 395                                         if (found) {
 396                                                 *offset = max_t(loff_t,
 397                                                         startoff, lastoff);
 398                                                 unlock_page(page);
 399                                                 goto out;
 400                                         }
 401                                         lastoff += bh->b_size;
 402                                         bh = bh->b_this_page;
 403                                 } while (bh != head);
 404                         }
 405
 406                         lastoff = page_offset(page) + PAGE_SIZE;
 407                         unlock_page(page);
 408                 }
 409
 410                 /*
 411                  * The no. of pages is less than our desired, that would be a
 412                  * hole in there.
 413                  */
 414                 if (nr_pages < num && whence == SEEK_HOLE) {
 415                         found = 1;
 416                         *offset = lastoff;
 417                         break;
 418                 }
 419
 420                 index = pvec.pages[i - 1]->index + 1;
 421                 pagevec_release(&pvec);
 422         } while (index <= end);
 423
 424 out:
 425         pagevec_release(&pvec);
 426         return found;
 427 }
 428
 429 /*
 430  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 431  */
 432 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 433 {
 434         struct inode *inode = file->f_mapping->host;
 435         struct ext4_map_blocks map;
 436         struct extent_status es;
 437         ext4_lblk_t start, last, end;
 438         loff_t dataoff, isize;
 439         int blkbits;
 440         int ret = 0;
 441
 442         mutex_lock(&inode->i_mutex);
 443
 444         isize = i_size_read(inode);
 445         if (offset >= isize) {
 446                 mutex_unlock(&inode->i_mutex);
 447                 return -ENXIO;
 448         }
 449
 450         blkbits = inode->i_sb->s_blocksize_bits;
 451         start = offset >> blkbits;
 452         last = start;
 453         end = isize >> blkbits;
 454         dataoff = offset;
 455
 456         do {
 457                 map.m_lblk = last;
 458                 map.m_len = end - last + 1;
 459                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 460                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 461                         if (last != start)
 462                                 dataoff = (loff_t)last << blkbits;
 463                         break;
 464                 }
 465
 466                 /*
 467                  * If there is a delay extent at this offset,
 468                  * it will be as a data.
 469                  */
 470                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 471                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 472                         if (last != start)
 473                                 dataoff = (loff_t)last << blkbits;
 474                         break;
 475                 }
 476
 477                 /*
 478                  * If there is a unwritten extent at this offset,
 479                  * it will be as a data or a hole according to page
 480                  * cache that has data or not.
 481                  */
 482                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 483                         int unwritten;
 484                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 485                                                               &map, &dataoff);
 486                         if (unwritten)
 487                                 break;
 488                 }
 489
 490                 last++;
 491                 dataoff = (loff_t)last << blkbits;
 492         } while (last <= end);
 493
 494         mutex_unlock(&inode->i_mutex);
 495
 496         if (dataoff > isize)
 497                 return -ENXIO;
 498
 499         return vfs_setpos(file, dataoff, maxsize);
 500 }
 501
 502 /*
 503  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 504  */
 505 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 506 {
 507         struct inode *inode = file->f_mapping->host;
 508         struct ext4_map_blocks map;
 509         struct extent_status es;
 510         ext4_lblk_t start, last, end;
 511         loff_t holeoff, isize;
 512         int blkbits;
 513         int ret = 0;
 514
 515         mutex_lock(&inode->i_mutex);
 516
 517         isize = i_size_read(inode);
 518         if (offset >= isize) {
 519                 mutex_unlock(&inode->i_mutex);
 520                 return -ENXIO;
 521         }
 522
 523         blkbits = inode->i_sb->s_blocksize_bits;
 524         start = offset >> blkbits;
 525         last = start;
 526         end = isize >> blkbits;
 527         holeoff = offset;
 528
 529         do {
 530                 map.m_lblk = last;
 531                 map.m_len = end - last + 1;
 532                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 533                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 534                         last += ret;
 535                         holeoff = (loff_t)last << blkbits;
 536                         continue;
 537                 }
 538
 539                 /*
 540                  * If there is a delay extent at this offset,
 541                  * we will skip this extent.
 542                  */
 543                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 544                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 545                         last = es.es_lblk + es.es_len;
 546                         holeoff = (loff_t)last << blkbits;
 547                         continue;
 548                 }
 549
 550                 /*
 551                  * If there is a unwritten extent at this offset,
 552                  * it will be as a data or a hole according to page
 553                  * cache that has data or not.
 554                  */
 555                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 556                         int unwritten;
 557                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 558                                                               &map, &holeoff);
 559                         if (!unwritten) {
 560                                 last += ret;
 561                                 holeoff = (loff_t)last << blkbits;
 562                                 continue;
 563                         }
 564                 }
 565
 566                 /* find a hole */
 567                 break;
 568         } while (last <= end);
 569
 570         mutex_unlock(&inode->i_mutex);
 571
 572         if (holeoff > isize)
 573                 holeoff = isize;
 574
 575         return vfs_setpos(file, holeoff, maxsize);
 576 }
 577
 578 /*
 579  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 580  * by calling generic_file_llseek_size() with the appropriate maxbytes
 581  * value for each.
 582  */
 583 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 584 {
 585         struct inode *inode = file->f_mapping->host;
 586         loff_t maxbytes;
 587
 588         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 589                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 590         else
 591                 maxbytes = inode->i_sb->s_maxbytes;
 592
 593         switch (whence) {
 594         case SEEK_SET:
 595         case SEEK_CUR:
 596         case SEEK_END:
 597                 return generic_file_llseek_size(file, offset, whence,
 598                                                 maxbytes, i_size_read(inode));
 599         case SEEK_DATA:
 600                 return ext4_seek_data(file, offset, maxbytes);
 601         case SEEK_HOLE:
 602                 return ext4_seek_hole(file, offset, maxbytes);
 603         }
 604
 605         return -EINVAL;
 606 }
 607
 608 const struct file_operations ext4_file_operations = {
 609         .llseek         = ext4_llseek,
 610         .read           = new_sync_read,
 611         .write          = new_sync_write,
 612         .read_iter      = generic_file_read_iter,
 613         .write_iter     = ext4_file_write_iter,
 614         .unlocked_ioctl = ext4_ioctl,
 615 #ifdef CONFIG_COMPAT
 616         .compat_ioctl   = ext4_compat_ioctl,
 617 #endif
 618         .mmap           = ext4_file_mmap,
 619         .open           = ext4_file_open,
 620         .release        = ext4_release_file,
 621         .fsync          = ext4_sync_file,
 622         .splice_read    = generic_file_splice_read,
 623         .splice_write   = iter_file_splice_write,
 624         .fallocate      = ext4_fallocate,
 625 };
 626
 627 #ifdef CONFIG_FS_DAX
 628 const struct file_operations ext4_dax_file_operations = {
 629         .llseek         = ext4_llseek,
 630         .read           = new_sync_read,
 631         .write          = new_sync_write,
 632         .read_iter      = generic_file_read_iter,
 633         .write_iter     = ext4_file_write_iter,
 634         .unlocked_ioctl = ext4_ioctl,
 635 #ifdef CONFIG_COMPAT
 636         .compat_ioctl   = ext4_compat_ioctl,
 637 #endif
 638         .mmap           = ext4_file_mmap,
 639         .open           = ext4_file_open,
 640         .release        = ext4_release_file,
 641         .fsync          = ext4_sync_file,
 642         /* Splice not yet supported with DAX */
 643         .fallocate      = ext4_fallocate,
 644 };
 645 #endif
 646
 647 const struct inode_operations ext4_file_inode_operations = {
 648         .setattr        = ext4_setattr,
 649         .getattr        = ext4_getattr,
 650         .setxattr       = generic_setxattr,
 651         .getxattr       = generic_getxattr,
 652         .listxattr      = ext4_listxattr,
 653         .removexattr    = generic_removexattr,
 654         .get_acl        = ext4_get_acl,
 655         .set_acl        = ext4_set_acl,
 656         .fiemap         = ext4_fiemap,
 657 };
 658