kernel/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/mount.h>
  24 #include <linux/path.h>
  25 #include <linux/quotaops.h>
  26 #include <linux/pagevec.h>
  27 #include <linux/uio.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 static 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, struct iov_iter *from, loff_t pos)
  77 {
  78         struct super_block *sb = inode->i_sb;
  79         int blockmask = sb->s_blocksize - 1;
  80
  81         if (pos >= i_size_read(inode))
  82                 return 0;
  83
  84         if ((pos | iov_iter_alignment(from)) & blockmask)
  85                 return 1;
  86
  87         return 0;
  88 }
  89
  90 static ssize_t
  91 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
  92 {
  93         struct file *file = iocb->ki_filp;
  94         struct inode *inode = file_inode(iocb->ki_filp);
  95         struct mutex *aio_mutex = NULL;
  96         struct blk_plug plug;
  97         int o_direct = iocb->ki_flags & IOCB_DIRECT;
  98         int overwrite = 0;
  99         ssize_t ret;
 100
 101         /*
 102          * Unaligned direct AIO must be serialized; see comment above
 103          * In the case of O_APPEND, assume that we must always serialize
 104          */
 105         if (o_direct &&
 106             ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
 107             !is_sync_kiocb(iocb) &&
 108             (iocb->ki_flags & IOCB_APPEND ||
 109              ext4_unaligned_aio(inode, from, iocb->ki_pos))) {
 110                 aio_mutex = ext4_aio_mutex(inode);
 111                 mutex_lock(aio_mutex);
 112                 ext4_unwritten_wait(inode);
 113         }
 114
 115         mutex_lock(&inode->i_mutex);
 116         ret = generic_write_checks(iocb, from);
 117         if (ret <= 0)
 118                 goto out;
 119
 120         /*
 121          * If we have encountered a bitmap-format file, the size limit
 122          * is smaller than s_maxbytes, which is for extent-mapped files.
 123          */
 124         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 125                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 126
 127                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) {
 128                         ret = -EFBIG;
 129                         goto out;
 130                 }
 131                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 132         }
 133
 134         iocb->private = &overwrite;
 135         if (o_direct) {
 136                 size_t length = iov_iter_count(from);
 137                 loff_t pos = iocb->ki_pos;
 138                 blk_start_plug(&plug);
 139
 140                 /* check whether we do a DIO overwrite or not */
 141                 if (ext4_should_dioread_nolock(inode) && !aio_mutex &&
 142                     !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
 143                         struct ext4_map_blocks map;
 144                         unsigned int blkbits = inode->i_blkbits;
 145                         int err, len;
 146
 147                         map.m_lblk = pos >> blkbits;
 148                         map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
 149                                 - map.m_lblk;
 150                         len = map.m_len;
 151
 152                         err = ext4_map_blocks(NULL, inode, &map, 0);
 153                         /*
 154                          * 'err==len' means that all of blocks has
 155                          * been preallocated no matter they are
 156                          * initialized or not.  For excluding
 157                          * unwritten extents, we need to check
 158                          * m_flags.  There are two conditions that
 159                          * indicate for initialized extents.  1) If we
 160                          * hit extent cache, EXT4_MAP_MAPPED flag is
 161                          * returned; 2) If we do a real lookup,
 162                          * non-flags are returned.  So we should check
 163                          * these two conditions.
 164                          */
 165                         if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
 166                                 overwrite = 1;
 167                 }
 168         }
 169
 170         ret = __generic_file_write_iter(iocb, from);
 171         mutex_unlock(&inode->i_mutex);
 172
 173         if (ret > 0) {
 174                 ssize_t err;
 175
 176                 err = generic_write_sync(file, iocb->ki_pos - ret, ret);
 177                 if (err < 0)
 178                         ret = err;
 179         }
 180         if (o_direct)
 181                 blk_finish_plug(&plug);
 182
 183         if (aio_mutex)
 184                 mutex_unlock(aio_mutex);
 185         return ret;
 186
 187 out:
 188         mutex_unlock(&inode->i_mutex);
 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         .pfn_mkwrite    = dax_pfn_mkwrite,
 210 };
 211 #else
 212 #define ext4_dax_vm_ops ext4_file_vm_ops
 213 #endif
 214
 215 static const struct vm_operations_struct ext4_file_vm_ops = {
 216         .fault          = filemap_fault,
 217         .map_pages      = filemap_map_pages,
 218         .page_mkwrite   = ext4_page_mkwrite,
 219 };
 220
 221 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 222 {
 223         struct inode *inode = file->f_mapping->host;
 224
 225         if (ext4_encrypted_inode(inode)) {
 226                 int err = ext4_generate_encryption_key(inode);
 227                 if (err)
 228                         return 0;
 229         }
 230         file_accessed(file);
 231         if (IS_DAX(file_inode(file))) {
 232                 vma->vm_ops = &ext4_dax_vm_ops;
 233                 vma->vm_flags |= VM_MIXEDMAP;
 234         } else {
 235                 vma->vm_ops = &ext4_file_vm_ops;
 236         }
 237         return 0;
 238 }
 239
 240 static int ext4_file_open(struct inode * inode, struct file * filp)
 241 {
 242         struct super_block *sb = inode->i_sb;
 243         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 244         struct vfsmount *mnt = filp->f_path.mnt;
 245         struct path path;
 246         char buf[64], *cp;
 247         int ret;
 248
 249         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 250                      !(sb->s_flags & MS_RDONLY))) {
 251                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 252                 /*
 253                  * Sample where the filesystem has been mounted and
 254                  * store it in the superblock for sysadmin convenience
 255                  * when trying to sort through large numbers of block
 256                  * devices or filesystem images.
 257                  */
 258                 memset(buf, 0, sizeof(buf));
 259                 path.mnt = mnt;
 260                 path.dentry = mnt->mnt_root;
 261                 cp = d_path(&path, buf, sizeof(buf));
 262                 if (!IS_ERR(cp)) {
 263                         handle_t *handle;
 264                         int err;
 265
 266                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 267                         if (IS_ERR(handle))
 268                                 return PTR_ERR(handle);
 269                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 270                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 271                         if (err) {
 272                                 ext4_journal_stop(handle);
 273                                 return err;
 274                         }
 275                         strlcpy(sbi->s_es->s_last_mounted, cp,
 276                                 sizeof(sbi->s_es->s_last_mounted));
 277                         ext4_handle_dirty_super(handle, sb);
 278                         ext4_journal_stop(handle);
 279                 }
 280         }
 281         /*
 282          * Set up the jbd2_inode if we are opening the inode for
 283          * writing and the journal is present
 284          */
 285         if (filp->f_mode & FMODE_WRITE) {
 286                 ret = ext4_inode_attach_jinode(inode);
 287                 if (ret < 0)
 288                         return ret;
 289         }
 290         ret = dquot_file_open(inode, filp);
 291         if (!ret && ext4_encrypted_inode(inode)) {
 292                 ret = ext4_generate_encryption_key(inode);
 293                 if (ret)
 294                         ret = -EACCES;
 295         }
 296         return ret;
 297 }
 298
 299 /*
 300  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 301  * file rather than ext4_ext_walk_space() because we can introduce
 302  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 303  * function.  When extent status tree has been fully implemented, it will
 304  * track all extent status for a file and we can directly use it to
 305  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 306  */
 307
 308 /*
 309  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 310  * lookup page cache to check whether or not there has some data between
 311  * [startoff, endoff] because, if this range contains an unwritten extent,
 312  * we determine this extent as a data or a hole according to whether the
 313  * page cache has data or not.
 314  */
 315 static int ext4_find_unwritten_pgoff(struct inode *inode,
 316                                      int whence,
 317                                      struct ext4_map_blocks *map,
 318                                      loff_t *offset)
 319 {
 320         struct pagevec pvec;
 321         unsigned int blkbits;
 322         pgoff_t index;
 323         pgoff_t end;
 324         loff_t endoff;
 325         loff_t startoff;
 326         loff_t lastoff;
 327         int found = 0;
 328
 329         blkbits = inode->i_sb->s_blocksize_bits;
 330         startoff = *offset;
 331         lastoff = startoff;
 332         endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
 333
 334         index = startoff >> PAGE_CACHE_SHIFT;
 335         end = endoff >> PAGE_CACHE_SHIFT;
 336
 337         pagevec_init(&pvec, 0);
 338         do {
 339                 int i, num;
 340                 unsigned long nr_pages;
 341
 342                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
 343                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 344                                           (pgoff_t)num);
 345                 if (nr_pages == 0) {
 346                         if (whence == SEEK_DATA)
 347                                 break;
 348
 349                         BUG_ON(whence != SEEK_HOLE);
 350                         /*
 351                          * If this is the first time to go into the loop and
 352                          * offset is not beyond the end offset, it will be a
 353                          * hole at this offset
 354                          */
 355                         if (lastoff == startoff || lastoff < endoff)
 356                                 found = 1;
 357                         break;
 358                 }
 359
 360                 /*
 361                  * If this is the first time to go into the loop and
 362                  * offset is smaller than the first page offset, it will be a
 363                  * hole at this offset.
 364                  */
 365                 if (lastoff == startoff && whence == SEEK_HOLE &&
 366                     lastoff < page_offset(pvec.pages[0])) {
 367                         found = 1;
 368                         break;
 369                 }
 370
 371                 for (i = 0; i < nr_pages; i++) {
 372                         struct page *page = pvec.pages[i];
 373                         struct buffer_head *bh, *head;
 374
 375                         /*
 376                          * If the current offset is not beyond the end of given
 377                          * range, it will be a hole.
 378                          */
 379                         if (lastoff < endoff && whence == SEEK_HOLE &&
 380                             page->index > end) {
 381                                 found = 1;
 382                                 *offset = lastoff;
 383                                 goto out;
 384                         }
 385
 386                         lock_page(page);
 387
 388                         if (unlikely(page->mapping != inode->i_mapping)) {
 389                                 unlock_page(page);
 390                                 continue;
 391                         }
 392
 393                         if (!page_has_buffers(page)) {
 394                                 unlock_page(page);
 395                                 continue;
 396                         }
 397
 398                         if (page_has_buffers(page)) {
 399                                 lastoff = page_offset(page);
 400                                 bh = head = page_buffers(page);
 401                                 do {
 402                                         if (buffer_uptodate(bh) ||
 403                                             buffer_unwritten(bh)) {
 404                                                 if (whence == SEEK_DATA)
 405                                                         found = 1;
 406                                         } else {
 407                                                 if (whence == SEEK_HOLE)
 408                                                         found = 1;
 409                                         }
 410                                         if (found) {
 411                                                 *offset = max_t(loff_t,
 412                                                         startoff, lastoff);
 413                                                 unlock_page(page);
 414                                                 goto out;
 415                                         }
 416                                         lastoff += bh->b_size;
 417                                         bh = bh->b_this_page;
 418                                 } while (bh != head);
 419                         }
 420
 421                         lastoff = page_offset(page) + PAGE_SIZE;
 422                         unlock_page(page);
 423                 }
 424
 425                 /*
 426                  * The no. of pages is less than our desired, that would be a
 427                  * hole in there.
 428                  */
 429                 if (nr_pages < num && whence == SEEK_HOLE) {
 430                         found = 1;
 431                         *offset = lastoff;
 432                         break;
 433                 }
 434
 435                 index = pvec.pages[i - 1]->index + 1;
 436                 pagevec_release(&pvec);
 437         } while (index <= end);
 438
 439 out:
 440         pagevec_release(&pvec);
 441         return found;
 442 }
 443
 444 /*
 445  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 446  */
 447 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 448 {
 449         struct inode *inode = file->f_mapping->host;
 450         struct ext4_map_blocks map;
 451         struct extent_status es;
 452         ext4_lblk_t start, last, end;
 453         loff_t dataoff, isize;
 454         int blkbits;
 455         int ret = 0;
 456
 457         mutex_lock(&inode->i_mutex);
 458
 459         isize = i_size_read(inode);
 460         if (offset >= isize) {
 461                 mutex_unlock(&inode->i_mutex);
 462                 return -ENXIO;
 463         }
 464
 465         blkbits = inode->i_sb->s_blocksize_bits;
 466         start = offset >> blkbits;
 467         last = start;
 468         end = isize >> blkbits;
 469         dataoff = offset;
 470
 471         do {
 472                 map.m_lblk = last;
 473                 map.m_len = end - last + 1;
 474                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 475                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 476                         if (last != start)
 477                                 dataoff = (loff_t)last << blkbits;
 478                         break;
 479                 }
 480
 481                 /*
 482                  * If there is a delay extent at this offset,
 483                  * it will be as a data.
 484                  */
 485                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 486                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 487                         if (last != start)
 488                                 dataoff = (loff_t)last << blkbits;
 489                         break;
 490                 }
 491
 492                 /*
 493                  * If there is a unwritten extent at this offset,
 494                  * it will be as a data or a hole according to page
 495                  * cache that has data or not.
 496                  */
 497                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 498                         int unwritten;
 499                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 500                                                               &map, &dataoff);
 501                         if (unwritten)
 502                                 break;
 503                 }
 504
 505                 last++;
 506                 dataoff = (loff_t)last << blkbits;
 507         } while (last <= end);
 508
 509         mutex_unlock(&inode->i_mutex);
 510
 511         if (dataoff > isize)
 512                 return -ENXIO;
 513
 514         return vfs_setpos(file, dataoff, maxsize);
 515 }
 516
 517 /*
 518  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 519  */
 520 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 521 {
 522         struct inode *inode = file->f_mapping->host;
 523         struct ext4_map_blocks map;
 524         struct extent_status es;
 525         ext4_lblk_t start, last, end;
 526         loff_t holeoff, isize;
 527         int blkbits;
 528         int ret = 0;
 529
 530         mutex_lock(&inode->i_mutex);
 531
 532         isize = i_size_read(inode);
 533         if (offset >= isize) {
 534                 mutex_unlock(&inode->i_mutex);
 535                 return -ENXIO;
 536         }
 537
 538         blkbits = inode->i_sb->s_blocksize_bits;
 539         start = offset >> blkbits;
 540         last = start;
 541         end = isize >> blkbits;
 542         holeoff = offset;
 543
 544         do {
 545                 map.m_lblk = last;
 546                 map.m_len = end - last + 1;
 547                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 548                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 549                         last += ret;
 550                         holeoff = (loff_t)last << blkbits;
 551                         continue;
 552                 }
 553
 554                 /*
 555                  * If there is a delay extent at this offset,
 556                  * we will skip this extent.
 557                  */
 558                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 559                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 560                         last = es.es_lblk + es.es_len;
 561                         holeoff = (loff_t)last << blkbits;
 562                         continue;
 563                 }
 564
 565                 /*
 566                  * If there is a unwritten extent at this offset,
 567                  * it will be as a data or a hole according to page
 568                  * cache that has data or not.
 569                  */
 570                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 571                         int unwritten;
 572                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 573                                                               &map, &holeoff);
 574                         if (!unwritten) {
 575                                 last += ret;
 576                                 holeoff = (loff_t)last << blkbits;
 577                                 continue;
 578                         }
 579                 }
 580
 581                 /* find a hole */
 582                 break;
 583         } while (last <= end);
 584
 585         mutex_unlock(&inode->i_mutex);
 586
 587         if (holeoff > isize)
 588                 holeoff = isize;
 589
 590         return vfs_setpos(file, holeoff, maxsize);
 591 }
 592
 593 /*
 594  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 595  * by calling generic_file_llseek_size() with the appropriate maxbytes
 596  * value for each.
 597  */
 598 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 599 {
 600         struct inode *inode = file->f_mapping->host;
 601         loff_t maxbytes;
 602
 603         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 604                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 605         else
 606                 maxbytes = inode->i_sb->s_maxbytes;
 607
 608         switch (whence) {
 609         case SEEK_SET:
 610         case SEEK_CUR:
 611         case SEEK_END:
 612                 return generic_file_llseek_size(file, offset, whence,
 613                                                 maxbytes, i_size_read(inode));
 614         case SEEK_DATA:
 615                 return ext4_seek_data(file, offset, maxbytes);
 616         case SEEK_HOLE:
 617                 return ext4_seek_hole(file, offset, maxbytes);
 618         }
 619
 620         return -EINVAL;
 621 }
 622
 623 const struct file_operations ext4_file_operations = {
 624         .llseek         = ext4_llseek,
 625         .read_iter      = generic_file_read_iter,
 626         .write_iter     = ext4_file_write_iter,
 627         .unlocked_ioctl = ext4_ioctl,
 628 #ifdef CONFIG_COMPAT
 629         .compat_ioctl   = ext4_compat_ioctl,
 630 #endif
 631         .mmap           = ext4_file_mmap,
 632         .open           = ext4_file_open,
 633         .release        = ext4_release_file,
 634         .fsync          = ext4_sync_file,
 635         .splice_read    = generic_file_splice_read,
 636         .splice_write   = iter_file_splice_write,
 637         .fallocate      = ext4_fallocate,
 638 };
 639
 640 const struct inode_operations ext4_file_inode_operations = {
 641         .setattr        = ext4_setattr,
 642         .getattr        = ext4_getattr,
 643         .setxattr       = generic_setxattr,
 644         .getxattr       = generic_getxattr,
 645         .listxattr      = ext4_listxattr,
 646         .removexattr    = generic_removexattr,
 647         .get_acl        = ext4_get_acl,
 648         .set_acl        = ext4_set_acl,
 649         .fiemap         = ext4_fiemap,
 650 };
 651