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/dax.h>
  26 #include <linux/quotaops.h>
  27 #include <linux/pagevec.h>
  28 #include <linux/uio.h>
  29 #include "ext4.h"
  30 #include "ext4_jbd2.h"
  31 #include "xattr.h"
  32 #include "acl.h"
  33
  34 #ifdef CONFIG_FS_DAX
  35 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
  36 {
  37         struct inode *inode = file_inode(iocb->ki_filp);
  38         ssize_t ret;
  39
  40         inode_lock_shared(inode);
  41         /*
  42          * Recheck under inode lock - at this point we are sure it cannot
  43          * change anymore
  44          */
  45         if (!IS_DAX(inode)) {
  46                 inode_unlock_shared(inode);
  47                 /* Fallback to buffered IO in case we cannot support DAX */
  48                 return generic_file_read_iter(iocb, to);
  49         }
  50         ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
  51         inode_unlock_shared(inode);
  52
  53         file_accessed(iocb->ki_filp);
  54         return ret;
  55 }
  56 #endif
  57
  58 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  59 {
  60         if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb))))
  61                 return -EIO;
  62
  63         if (!iov_iter_count(to))
  64                 return 0; /* skip atime */
  65
  66 #ifdef CONFIG_FS_DAX
  67         if (IS_DAX(file_inode(iocb->ki_filp)))
  68                 return ext4_dax_read_iter(iocb, to);
  69 #endif
  70         return generic_file_read_iter(iocb, to);
  71 }
  72
  73 /*
  74  * Called when an inode is released. Note that this is different
  75  * from ext4_file_open: open gets called at every open, but release
  76  * gets called only when /all/ the files are closed.
  77  */
  78 static int ext4_release_file(struct inode *inode, struct file *filp)
  79 {
  80         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
  81                 ext4_alloc_da_blocks(inode);
  82                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
  83         }
  84         /* if we are the last writer on the inode, drop the block reservation */
  85         if ((filp->f_mode & FMODE_WRITE) &&
  86                         (atomic_read(&inode->i_writecount) == 1) &&
  87                         !EXT4_I(inode)->i_reserved_data_blocks)
  88         {
  89                 down_write(&EXT4_I(inode)->i_data_sem);
  90                 ext4_discard_preallocations(inode);
  91                 up_write(&EXT4_I(inode)->i_data_sem);
  92         }
  93         if (is_dx(inode) && filp->private_data)
  94                 ext4_htree_free_dir_info(filp->private_data);
  95
  96         return 0;
  97 }
  98
  99 static void ext4_unwritten_wait(struct inode *inode)
 100 {
 101         wait_queue_head_t *wq = ext4_ioend_wq(inode);
 102
 103         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
 104 }
 105
 106 /*
 107  * This tests whether the IO in question is block-aligned or not.
 108  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 109  * are converted to written only after the IO is complete.  Until they are
 110  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 111  * it needs to zero out portions of the start and/or end block.  If 2 AIO
 112  * threads are at work on the same unwritten block, they must be synchronized
 113  * or one thread will zero the other's data, causing corruption.
 114  */
 115 static int
 116 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
 117 {
 118         struct super_block *sb = inode->i_sb;
 119         int blockmask = sb->s_blocksize - 1;
 120
 121         if (pos >= i_size_read(inode))
 122                 return 0;
 123
 124         if ((pos | iov_iter_alignment(from)) & blockmask)
 125                 return 1;
 126
 127         return 0;
 128 }
 129
 130 /* Is IO overwriting allocated and initialized blocks? */
 131 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
 132 {
 133         struct ext4_map_blocks map;
 134         unsigned int blkbits = inode->i_blkbits;
 135         int err, blklen;
 136
 137         if (pos + len > i_size_read(inode))
 138                 return false;
 139
 140         map.m_lblk = pos >> blkbits;
 141         map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
 142         blklen = map.m_len;
 143
 144         err = ext4_map_blocks(NULL, inode, &map, 0);
 145         /*
 146          * 'err==len' means that all of the blocks have been preallocated,
 147          * regardless of whether they have been initialized or not. To exclude
 148          * unwritten extents, we need to check m_flags.
 149          */
 150         return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
 151 }
 152
 153 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
 154 {
 155         struct inode *inode = file_inode(iocb->ki_filp);
 156         ssize_t ret;
 157
 158         ret = generic_write_checks(iocb, from);
 159         if (ret <= 0)
 160                 return ret;
 161         /*
 162          * If we have encountered a bitmap-format file, the size limit
 163          * is smaller than s_maxbytes, which is for extent-mapped files.
 164          */
 165         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 166                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 167
 168                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
 169                         return -EFBIG;
 170                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 171         }
 172         return iov_iter_count(from);
 173 }
 174
 175 #ifdef CONFIG_FS_DAX
 176 static ssize_t
 177 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 178 {
 179         struct inode *inode = file_inode(iocb->ki_filp);
 180         ssize_t ret;
 181
 182         inode_lock(inode);
 183         ret = ext4_write_checks(iocb, from);
 184         if (ret <= 0)
 185                 goto out;
 186         ret = file_remove_privs(iocb->ki_filp);
 187         if (ret)
 188                 goto out;
 189         ret = file_update_time(iocb->ki_filp);
 190         if (ret)
 191                 goto out;
 192
 193         ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 194 out:
 195         inode_unlock(inode);
 196         if (ret > 0)
 197                 ret = generic_write_sync(iocb, ret);
 198         return ret;
 199 }
 200 #endif
 201
 202 static ssize_t
 203 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 204 {
 205         struct inode *inode = file_inode(iocb->ki_filp);
 206         int o_direct = iocb->ki_flags & IOCB_DIRECT;
 207         int unaligned_aio = 0;
 208         int overwrite = 0;
 209         ssize_t ret;
 210
 211         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 212                 return -EIO;
 213
 214 #ifdef CONFIG_FS_DAX
 215         if (IS_DAX(inode))
 216                 return ext4_dax_write_iter(iocb, from);
 217 #endif
 218
 219         inode_lock(inode);
 220         ret = ext4_write_checks(iocb, from);
 221         if (ret <= 0)
 222                 goto out;
 223
 224         /*
 225          * Unaligned direct AIO must be serialized among each other as zeroing
 226          * of partial blocks of two competing unaligned AIOs can result in data
 227          * corruption.
 228          */
 229         if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
 230             !is_sync_kiocb(iocb) &&
 231             ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
 232                 unaligned_aio = 1;
 233                 ext4_unwritten_wait(inode);
 234         }
 235
 236         iocb->private = &overwrite;
 237         /* Check whether we do a DIO overwrite or not */
 238         if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio &&
 239             ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from)))
 240                 overwrite = 1;
 241
 242         ret = __generic_file_write_iter(iocb, from);
 243         inode_unlock(inode);
 244
 245         if (ret > 0)
 246                 ret = generic_write_sync(iocb, ret);
 247
 248         return ret;
 249
 250 out:
 251         inode_unlock(inode);
 252         return ret;
 253 }
 254
 255 #ifdef CONFIG_FS_DAX
 256 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 257 {
 258         int result;
 259         struct inode *inode = file_inode(vma->vm_file);
 260         struct super_block *sb = inode->i_sb;
 261         bool write = vmf->flags & FAULT_FLAG_WRITE;
 262
 263         if (write) {
 264                 sb_start_pagefault(sb);
 265                 file_update_time(vma->vm_file);
 266         }
 267         down_read(&EXT4_I(inode)->i_mmap_sem);
 268         result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);
 269         up_read(&EXT4_I(inode)->i_mmap_sem);
 270         if (write)
 271                 sb_end_pagefault(sb);
 272
 273         return result;
 274 }
 275
 276 static int
 277 ext4_dax_pmd_fault(struct vm_fault *vmf)
 278 {
 279         int result;
 280         struct inode *inode = file_inode(vmf->vma->vm_file);
 281         struct super_block *sb = inode->i_sb;
 282         bool write = vmf->flags & FAULT_FLAG_WRITE;
 283
 284         if (write) {
 285                 sb_start_pagefault(sb);
 286                 file_update_time(vmf->vma->vm_file);
 287         }
 288         down_read(&EXT4_I(inode)->i_mmap_sem);
 289         result = dax_iomap_pmd_fault(vmf, &ext4_iomap_ops);
 290         up_read(&EXT4_I(inode)->i_mmap_sem);
 291         if (write)
 292                 sb_end_pagefault(sb);
 293
 294         return result;
 295 }
 296
 297 /*
 298  * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_fault()
 299  * handler we check for races agaist truncate. Note that since we cycle through
 300  * i_mmap_sem, we are sure that also any hole punching that began before we
 301  * were called is finished by now and so if it included part of the file we
 302  * are working on, our pte will get unmapped and the check for pte_same() in
 303  * wp_pfn_shared() fails. Thus fault gets retried and things work out as
 304  * desired.
 305  */
 306 static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
 307                                 struct vm_fault *vmf)
 308 {
 309         struct inode *inode = file_inode(vma->vm_file);
 310         struct super_block *sb = inode->i_sb;
 311         loff_t size;
 312         int ret;
 313
 314         sb_start_pagefault(sb);
 315         file_update_time(vma->vm_file);
 316         down_read(&EXT4_I(inode)->i_mmap_sem);
 317         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 318         if (vmf->pgoff >= size)
 319                 ret = VM_FAULT_SIGBUS;
 320         else
 321                 ret = dax_pfn_mkwrite(vma, vmf);
 322         up_read(&EXT4_I(inode)->i_mmap_sem);
 323         sb_end_pagefault(sb);
 324
 325         return ret;
 326 }
 327
 328 static const struct vm_operations_struct ext4_dax_vm_ops = {
 329         .fault          = ext4_dax_fault,
 330         .pmd_fault      = ext4_dax_pmd_fault,
 331         .page_mkwrite   = ext4_dax_fault,
 332         .pfn_mkwrite    = ext4_dax_pfn_mkwrite,
 333 };
 334 #else
 335 #define ext4_dax_vm_ops ext4_file_vm_ops
 336 #endif
 337
 338 static const struct vm_operations_struct ext4_file_vm_ops = {
 339         .fault          = ext4_filemap_fault,
 340         .map_pages      = filemap_map_pages,
 341         .page_mkwrite   = ext4_page_mkwrite,
 342 };
 343
 344 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 345 {
 346         struct inode *inode = file->f_mapping->host;
 347
 348         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 349                 return -EIO;
 350
 351         if (ext4_encrypted_inode(inode)) {
 352                 int err = fscrypt_get_encryption_info(inode);
 353                 if (err)
 354                         return 0;
 355                 if (!fscrypt_has_encryption_key(inode))
 356                         return -ENOKEY;
 357         }
 358         file_accessed(file);
 359         if (IS_DAX(file_inode(file))) {
 360                 vma->vm_ops = &ext4_dax_vm_ops;
 361                 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 362         } else {
 363                 vma->vm_ops = &ext4_file_vm_ops;
 364         }
 365         return 0;
 366 }
 367
 368 static int ext4_file_open(struct inode * inode, struct file * filp)
 369 {
 370         struct super_block *sb = inode->i_sb;
 371         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 372         struct vfsmount *mnt = filp->f_path.mnt;
 373         struct dentry *dir;
 374         struct path path;
 375         char buf[64], *cp;
 376         int ret;
 377
 378         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 379                 return -EIO;
 380
 381         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 382                      !(sb->s_flags & MS_RDONLY))) {
 383                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 384                 /*
 385                  * Sample where the filesystem has been mounted and
 386                  * store it in the superblock for sysadmin convenience
 387                  * when trying to sort through large numbers of block
 388                  * devices or filesystem images.
 389                  */
 390                 memset(buf, 0, sizeof(buf));
 391                 path.mnt = mnt;
 392                 path.dentry = mnt->mnt_root;
 393                 cp = d_path(&path, buf, sizeof(buf));
 394                 if (!IS_ERR(cp)) {
 395                         handle_t *handle;
 396                         int err;
 397
 398                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 399                         if (IS_ERR(handle))
 400                                 return PTR_ERR(handle);
 401                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 402                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 403                         if (err) {
 404                                 ext4_journal_stop(handle);
 405                                 return err;
 406                         }
 407                         strlcpy(sbi->s_es->s_last_mounted, cp,
 408                                 sizeof(sbi->s_es->s_last_mounted));
 409                         ext4_handle_dirty_super(handle, sb);
 410                         ext4_journal_stop(handle);
 411                 }
 412         }
 413         if (ext4_encrypted_inode(inode)) {
 414                 ret = fscrypt_get_encryption_info(inode);
 415                 if (ret)
 416                         return -EACCES;
 417                 if (!fscrypt_has_encryption_key(inode))
 418                         return -ENOKEY;
 419         }
 420
 421         dir = dget_parent(file_dentry(filp));
 422         if (ext4_encrypted_inode(d_inode(dir)) &&
 423                         !fscrypt_has_permitted_context(d_inode(dir), inode)) {
 424                 ext4_warning(inode->i_sb,
 425                              "Inconsistent encryption contexts: %lu/%lu",
 426                              (unsigned long) d_inode(dir)->i_ino,
 427                              (unsigned long) inode->i_ino);
 428                 dput(dir);
 429                 return -EPERM;
 430         }
 431         dput(dir);
 432         /*
 433          * Set up the jbd2_inode if we are opening the inode for
 434          * writing and the journal is present
 435          */
 436         if (filp->f_mode & FMODE_WRITE) {
 437                 ret = ext4_inode_attach_jinode(inode);
 438                 if (ret < 0)
 439                         return ret;
 440         }
 441         return dquot_file_open(inode, filp);
 442 }
 443
 444 /*
 445  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 446  * file rather than ext4_ext_walk_space() because we can introduce
 447  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 448  * function.  When extent status tree has been fully implemented, it will
 449  * track all extent status for a file and we can directly use it to
 450  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 451  */
 452
 453 /*
 454  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 455  * lookup page cache to check whether or not there has some data between
 456  * [startoff, endoff] because, if this range contains an unwritten extent,
 457  * we determine this extent as a data or a hole according to whether the
 458  * page cache has data or not.
 459  */
 460 static int ext4_find_unwritten_pgoff(struct inode *inode,
 461                                      int whence,
 462                                      ext4_lblk_t end_blk,
 463                                      loff_t *offset)
 464 {
 465         struct pagevec pvec;
 466         unsigned int blkbits;
 467         pgoff_t index;
 468         pgoff_t end;
 469         loff_t endoff;
 470         loff_t startoff;
 471         loff_t lastoff;
 472         int found = 0;
 473
 474         blkbits = inode->i_sb->s_blocksize_bits;
 475         startoff = *offset;
 476         lastoff = startoff;
 477         endoff = (loff_t)end_blk << blkbits;
 478
 479         index = startoff >> PAGE_SHIFT;
 480         end = endoff >> PAGE_SHIFT;
 481
 482         pagevec_init(&pvec, 0);
 483         do {
 484                 int i, num;
 485                 unsigned long nr_pages;
 486
 487                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
 488                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 489                                           (pgoff_t)num);
 490                 if (nr_pages == 0) {
 491                         if (whence == SEEK_DATA)
 492                                 break;
 493
 494                         BUG_ON(whence != SEEK_HOLE);
 495                         /*
 496                          * If this is the first time to go into the loop and
 497                          * offset is not beyond the end offset, it will be a
 498                          * hole at this offset
 499                          */
 500                         if (lastoff == startoff || lastoff < endoff)
 501                                 found = 1;
 502                         break;
 503                 }
 504
 505                 /*
 506                  * If this is the first time to go into the loop and
 507                  * offset is smaller than the first page offset, it will be a
 508                  * hole at this offset.
 509                  */
 510                 if (lastoff == startoff && whence == SEEK_HOLE &&
 511                     lastoff < page_offset(pvec.pages[0])) {
 512                         found = 1;
 513                         break;
 514                 }
 515
 516                 for (i = 0; i < nr_pages; i++) {
 517                         struct page *page = pvec.pages[i];
 518                         struct buffer_head *bh, *head;
 519
 520                         /*
 521                          * If the current offset is not beyond the end of given
 522                          * range, it will be a hole.
 523                          */
 524                         if (lastoff < endoff && whence == SEEK_HOLE &&
 525                             page->index > end) {
 526                                 found = 1;
 527                                 *offset = lastoff;
 528                                 goto out;
 529                         }
 530
 531                         lock_page(page);
 532
 533                         if (unlikely(page->mapping != inode->i_mapping)) {
 534                                 unlock_page(page);
 535                                 continue;
 536                         }
 537
 538                         if (!page_has_buffers(page)) {
 539                                 unlock_page(page);
 540                                 continue;
 541                         }
 542
 543                         if (page_has_buffers(page)) {
 544                                 lastoff = page_offset(page);
 545                                 bh = head = page_buffers(page);
 546                                 do {
 547                                         if (buffer_uptodate(bh) ||
 548                                             buffer_unwritten(bh)) {
 549                                                 if (whence == SEEK_DATA)
 550                                                         found = 1;
 551                                         } else {
 552                                                 if (whence == SEEK_HOLE)
 553                                                         found = 1;
 554                                         }
 555                                         if (found) {
 556                                                 *offset = max_t(loff_t,
 557                                                         startoff, lastoff);
 558                                                 unlock_page(page);
 559                                                 goto out;
 560                                         }
 561                                         lastoff += bh->b_size;
 562                                         bh = bh->b_this_page;
 563                                 } while (bh != head);
 564                         }
 565
 566                         lastoff = page_offset(page) + PAGE_SIZE;
 567                         unlock_page(page);
 568                 }
 569
 570                 /*
 571                  * The no. of pages is less than our desired, that would be a
 572                  * hole in there.
 573                  */
 574                 if (nr_pages < num && whence == SEEK_HOLE) {
 575                         found = 1;
 576                         *offset = lastoff;
 577                         break;
 578                 }
 579
 580                 index = pvec.pages[i - 1]->index + 1;
 581                 pagevec_release(&pvec);
 582         } while (index <= end);
 583
 584 out:
 585         pagevec_release(&pvec);
 586         return found;
 587 }
 588
 589 /*
 590  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 591  */
 592 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 593 {
 594         struct inode *inode = file->f_mapping->host;
 595         struct extent_status es;
 596         ext4_lblk_t start, last, end;
 597         loff_t dataoff, isize;
 598         int blkbits;
 599         int ret;
 600
 601         inode_lock(inode);
 602
 603         isize = i_size_read(inode);
 604         if (offset >= isize) {
 605                 inode_unlock(inode);
 606                 return -ENXIO;
 607         }
 608
 609         blkbits = inode->i_sb->s_blocksize_bits;
 610         start = offset >> blkbits;
 611         last = start;
 612         end = isize >> blkbits;
 613         dataoff = offset;
 614
 615         do {
 616                 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
 617                 if (ret <= 0) {
 618                         /* No extent found -> no data */
 619                         if (ret == 0)
 620                                 ret = -ENXIO;
 621                         inode_unlock(inode);
 622                         return ret;
 623                 }
 624
 625                 last = es.es_lblk;
 626                 if (last != start)
 627                         dataoff = (loff_t)last << blkbits;
 628                 if (!ext4_es_is_unwritten(&es))
 629                         break;
 630
 631                 /*
 632                  * If there is a unwritten extent at this offset,
 633                  * it will be as a data or a hole according to page
 634                  * cache that has data or not.
 635                  */
 636                 if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 637                                               es.es_lblk + es.es_len, &dataoff))
 638                         break;
 639                 last += es.es_len;
 640                 dataoff = (loff_t)last << blkbits;
 641                 cond_resched();
 642         } while (last <= end);
 643
 644         inode_unlock(inode);
 645
 646         if (dataoff > isize)
 647                 return -ENXIO;
 648
 649         return vfs_setpos(file, dataoff, maxsize);
 650 }
 651
 652 /*
 653  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 654  */
 655 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 656 {
 657         struct inode *inode = file->f_mapping->host;
 658         struct extent_status es;
 659         ext4_lblk_t start, last, end;
 660         loff_t holeoff, isize;
 661         int blkbits;
 662         int ret;
 663
 664         inode_lock(inode);
 665
 666         isize = i_size_read(inode);
 667         if (offset >= isize) {
 668                 inode_unlock(inode);
 669                 return -ENXIO;
 670         }
 671
 672         blkbits = inode->i_sb->s_blocksize_bits;
 673         start = offset >> blkbits;
 674         last = start;
 675         end = isize >> blkbits;
 676         holeoff = offset;
 677
 678         do {
 679                 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
 680                 if (ret < 0) {
 681                         inode_unlock(inode);
 682                         return ret;
 683                 }
 684                 /* Found a hole? */
 685                 if (ret == 0 || es.es_lblk > last) {
 686                         if (last != start)
 687                                 holeoff = (loff_t)last << blkbits;
 688                         break;
 689                 }
 690                 /*
 691                  * If there is a unwritten extent at this offset,
 692                  * it will be as a data or a hole according to page
 693                  * cache that has data or not.
 694                  */
 695                 if (ext4_es_is_unwritten(&es) &&
 696                     ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 697                                               last + es.es_len, &holeoff))
 698                         break;
 699
 700                 last += es.es_len;
 701                 holeoff = (loff_t)last << blkbits;
 702                 cond_resched();
 703         } while (last <= end);
 704
 705         inode_unlock(inode);
 706
 707         if (holeoff > isize)
 708                 holeoff = isize;
 709
 710         return vfs_setpos(file, holeoff, maxsize);
 711 }
 712
 713 /*
 714  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 715  * by calling generic_file_llseek_size() with the appropriate maxbytes
 716  * value for each.
 717  */
 718 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 719 {
 720         struct inode *inode = file->f_mapping->host;
 721         loff_t maxbytes;
 722
 723         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 724                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 725         else
 726                 maxbytes = inode->i_sb->s_maxbytes;
 727
 728         switch (whence) {
 729         case SEEK_SET:
 730         case SEEK_CUR:
 731         case SEEK_END:
 732                 return generic_file_llseek_size(file, offset, whence,
 733                                                 maxbytes, i_size_read(inode));
 734         case SEEK_DATA:
 735                 return ext4_seek_data(file, offset, maxbytes);
 736         case SEEK_HOLE:
 737                 return ext4_seek_hole(file, offset, maxbytes);
 738         }
 739
 740         return -EINVAL;
 741 }
 742
 743 const struct file_operations ext4_file_operations = {
 744         .llseek         = ext4_llseek,
 745         .read_iter      = ext4_file_read_iter,
 746         .write_iter     = ext4_file_write_iter,
 747         .unlocked_ioctl = ext4_ioctl,
 748 #ifdef CONFIG_COMPAT
 749         .compat_ioctl   = ext4_compat_ioctl,
 750 #endif
 751         .mmap           = ext4_file_mmap,
 752         .open           = ext4_file_open,
 753         .release        = ext4_release_file,
 754         .fsync          = ext4_sync_file,
 755         .get_unmapped_area = thp_get_unmapped_area,
 756         .splice_read    = generic_file_splice_read,
 757         .splice_write   = iter_file_splice_write,
 758         .fallocate      = ext4_fallocate,
 759 };
 760
 761 const struct inode_operations ext4_file_inode_operations = {
 762         .setattr        = ext4_setattr,
 763         .getattr        = ext4_getattr,
 764         .listxattr      = ext4_listxattr,
 765         .get_acl        = ext4_get_acl,
 766         .set_acl        = ext4_set_acl,
 767         .fiemap         = ext4_fiemap,
 768 };
 769