fs/ext4/file.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/file.c
   4  *
   5  * Copyright (C) 1992, 1993, 1994, 1995
   6  * Remy Card (card@masi.ibp.fr)
   7  * Laboratoire MASI - Institut Blaise Pascal
   8  * Universite Pierre et Marie Curie (Paris VI)
   9  *
  10  *  from
  11  *
  12  *  linux/fs/minix/file.c
  13  *
  14  *  Copyright (C) 1991, 1992  Linus Torvalds
  15  *
  16  *  ext4 fs regular file handling primitives
  17  *
  18  *  64-bit file support on 64-bit platforms by Jakub Jelinek
  19  *      (jj@sunsite.ms.mff.cuni.cz)
  20  */
  21
  22 #include <linux/time.h>
  23 #include <linux/fs.h>
  24 #include <linux/mount.h>
  25 #include <linux/path.h>
  26 #include <linux/dax.h>
  27 #include <linux/quotaops.h>
  28 #include <linux/pagevec.h>
  29 #include <linux/uio.h>
  30 #include "ext4.h"
  31 #include "ext4_jbd2.h"
  32 #include "xattr.h"
  33 #include "acl.h"
  34
  35 #ifdef CONFIG_FS_DAX
  36 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
  37 {
  38         struct inode *inode = file_inode(iocb->ki_filp);
  39         ssize_t ret;
  40
  41         if (iocb->ki_flags & IOCB_NOWAIT) {
  42                 if (!inode_trylock_shared(inode))
  43                         return -EAGAIN;
  44         } else {
  45                 inode_lock_shared(inode);
  46         }
  47         /*
  48          * Recheck under inode lock - at this point we are sure it cannot
  49          * change anymore
  50          */
  51         if (!IS_DAX(inode)) {
  52                 inode_unlock_shared(inode);
  53                 /* Fallback to buffered IO in case we cannot support DAX */
  54                 return generic_file_read_iter(iocb, to);
  55         }
  56         ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
  57         inode_unlock_shared(inode);
  58
  59         file_accessed(iocb->ki_filp);
  60         return ret;
  61 }
  62 #endif
  63
  64 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  65 {
  66         if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb))))
  67                 return -EIO;
  68
  69         if (!iov_iter_count(to))
  70                 return 0; /* skip atime */
  71
  72 #ifdef CONFIG_FS_DAX
  73         if (IS_DAX(file_inode(iocb->ki_filp)))
  74                 return ext4_dax_read_iter(iocb, to);
  75 #endif
  76         return generic_file_read_iter(iocb, to);
  77 }
  78
  79 /*
  80  * Called when an inode is released. Note that this is different
  81  * from ext4_file_open: open gets called at every open, but release
  82  * gets called only when /all/ the files are closed.
  83  */
  84 static int ext4_release_file(struct inode *inode, struct file *filp)
  85 {
  86         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
  87                 ext4_alloc_da_blocks(inode);
  88                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
  89         }
  90         /* if we are the last writer on the inode, drop the block reservation */
  91         if ((filp->f_mode & FMODE_WRITE) &&
  92                         (atomic_read(&inode->i_writecount) == 1) &&
  93                         !EXT4_I(inode)->i_reserved_data_blocks)
  94         {
  95                 down_write(&EXT4_I(inode)->i_data_sem);
  96                 ext4_discard_preallocations(inode);
  97                 up_write(&EXT4_I(inode)->i_data_sem);
  98         }
  99         if (is_dx(inode) && filp->private_data)
 100                 ext4_htree_free_dir_info(filp->private_data);
 101
 102         return 0;
 103 }
 104
 105 static void ext4_unwritten_wait(struct inode *inode)
 106 {
 107         wait_queue_head_t *wq = ext4_ioend_wq(inode);
 108
 109         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
 110 }
 111
 112 /*
 113  * This tests whether the IO in question is block-aligned or not.
 114  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 115  * are converted to written only after the IO is complete.  Until they are
 116  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 117  * it needs to zero out portions of the start and/or end block.  If 2 AIO
 118  * threads are at work on the same unwritten block, they must be synchronized
 119  * or one thread will zero the other's data, causing corruption.
 120  */
 121 static int
 122 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
 123 {
 124         struct super_block *sb = inode->i_sb;
 125         int blockmask = sb->s_blocksize - 1;
 126
 127         if (pos >= ALIGN(i_size_read(inode), sb->s_blocksize))
 128                 return 0;
 129
 130         if ((pos | iov_iter_alignment(from)) & blockmask)
 131                 return 1;
 132
 133         return 0;
 134 }
 135
 136 /* Is IO overwriting allocated and initialized blocks? */
 137 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
 138 {
 139         struct ext4_map_blocks map;
 140         unsigned int blkbits = inode->i_blkbits;
 141         int err, blklen;
 142
 143         if (pos + len > i_size_read(inode))
 144                 return false;
 145
 146         map.m_lblk = pos >> blkbits;
 147         map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
 148         blklen = map.m_len;
 149
 150         err = ext4_map_blocks(NULL, inode, &map, 0);
 151         /*
 152          * 'err==len' means that all of the blocks have been preallocated,
 153          * regardless of whether they have been initialized or not. To exclude
 154          * unwritten extents, we need to check m_flags.
 155          */
 156         return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
 157 }
 158
 159 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
 160 {
 161         struct inode *inode = file_inode(iocb->ki_filp);
 162         ssize_t ret;
 163
 164         ret = generic_write_checks(iocb, from);
 165         if (ret <= 0)
 166                 return ret;
 167
 168         if (unlikely(IS_IMMUTABLE(inode)))
 169                 return -EPERM;
 170
 171         /*
 172          * If we have encountered a bitmap-format file, the size limit
 173          * is smaller than s_maxbytes, which is for extent-mapped files.
 174          */
 175         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 176                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 177
 178                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
 179                         return -EFBIG;
 180                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 181         }
 182         return iov_iter_count(from);
 183 }
 184
 185 #ifdef CONFIG_FS_DAX
 186 static ssize_t
 187 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 188 {
 189         struct inode *inode = file_inode(iocb->ki_filp);
 190         ssize_t ret;
 191
 192         if (iocb->ki_flags & IOCB_NOWAIT) {
 193                 if (!inode_trylock(inode))
 194                         return -EAGAIN;
 195         } else {
 196                 inode_lock(inode);
 197         }
 198         ret = ext4_write_checks(iocb, from);
 199         if (ret <= 0)
 200                 goto out;
 201         ret = file_remove_privs(iocb->ki_filp);
 202         if (ret)
 203                 goto out;
 204         ret = file_update_time(iocb->ki_filp);
 205         if (ret)
 206                 goto out;
 207
 208         ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 209 out:
 210         inode_unlock(inode);
 211         if (ret > 0)
 212                 ret = generic_write_sync(iocb, ret);
 213         return ret;
 214 }
 215 #endif
 216
 217 static ssize_t
 218 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 219 {
 220         struct inode *inode = file_inode(iocb->ki_filp);
 221         int o_direct = iocb->ki_flags & IOCB_DIRECT;
 222         int unaligned_aio = 0;
 223         int overwrite = 0;
 224         ssize_t ret;
 225
 226         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 227                 return -EIO;
 228
 229 #ifdef CONFIG_FS_DAX
 230         if (IS_DAX(inode))
 231                 return ext4_dax_write_iter(iocb, from);
 232 #endif
 233         if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT))
 234                 return -EOPNOTSUPP;
 235
 236         if (!inode_trylock(inode)) {
 237                 if (iocb->ki_flags & IOCB_NOWAIT)
 238                         return -EAGAIN;
 239                 inode_lock(inode);
 240         }
 241
 242         ret = ext4_write_checks(iocb, from);
 243         if (ret <= 0)
 244                 goto out;
 245
 246         /*
 247          * Unaligned direct AIO must be serialized among each other as zeroing
 248          * of partial blocks of two competing unaligned AIOs can result in data
 249          * corruption.
 250          */
 251         if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
 252             !is_sync_kiocb(iocb) &&
 253             ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
 254                 unaligned_aio = 1;
 255                 ext4_unwritten_wait(inode);
 256         }
 257
 258         iocb->private = &overwrite;
 259         /* Check whether we do a DIO overwrite or not */
 260         if (o_direct && !unaligned_aio) {
 261                 if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
 262                         if (ext4_should_dioread_nolock(inode))
 263                                 overwrite = 1;
 264                 } else if (iocb->ki_flags & IOCB_NOWAIT) {
 265                         ret = -EAGAIN;
 266                         goto out;
 267                 }
 268         }
 269
 270         ret = __generic_file_write_iter(iocb, from);
 271         /*
 272          * Unaligned direct AIO must be the only IO in flight. Otherwise
 273          * overlapping aligned IO after unaligned might result in data
 274          * corruption.
 275          */
 276         if (ret == -EIOCBQUEUED && unaligned_aio)
 277                 ext4_unwritten_wait(inode);
 278         inode_unlock(inode);
 279
 280         if (ret > 0)
 281                 ret = generic_write_sync(iocb, ret);
 282
 283         return ret;
 284
 285 out:
 286         inode_unlock(inode);
 287         return ret;
 288 }
 289
 290 #ifdef CONFIG_FS_DAX
 291 static int ext4_dax_huge_fault(struct vm_fault *vmf,
 292                 enum page_entry_size pe_size)
 293 {
 294         int result;
 295         handle_t *handle = NULL;
 296         struct inode *inode = file_inode(vmf->vma->vm_file);
 297         struct super_block *sb = inode->i_sb;
 298
 299         /*
 300          * We have to distinguish real writes from writes which will result in a
 301          * COW page; COW writes should *not* poke the journal (the file will not
 302          * be changed). Doing so would cause unintended failures when mounted
 303          * read-only.
 304          *
 305          * We check for VM_SHARED rather than vmf->cow_page since the latter is
 306          * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
 307          * other sizes, dax_iomap_fault will handle splitting / fallback so that
 308          * we eventually come back with a COW page.
 309          */
 310         bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
 311                 (vmf->vma->vm_flags & VM_SHARED);
 312
 313         if (write) {
 314                 sb_start_pagefault(sb);
 315                 file_update_time(vmf->vma->vm_file);
 316                 down_read(&EXT4_I(inode)->i_mmap_sem);
 317                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 318                                                EXT4_DATA_TRANS_BLOCKS(sb));
 319         } else {
 320                 down_read(&EXT4_I(inode)->i_mmap_sem);
 321         }
 322         if (!IS_ERR(handle))
 323                 result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops);
 324         else
 325                 result = VM_FAULT_SIGBUS;
 326         if (write) {
 327                 if (!IS_ERR(handle))
 328                         ext4_journal_stop(handle);
 329                 up_read(&EXT4_I(inode)->i_mmap_sem);
 330                 sb_end_pagefault(sb);
 331         } else {
 332                 up_read(&EXT4_I(inode)->i_mmap_sem);
 333         }
 334
 335         return result;
 336 }
 337
 338 static int ext4_dax_fault(struct vm_fault *vmf)
 339 {
 340         return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 341 }
 342
 343 static const struct vm_operations_struct ext4_dax_vm_ops = {
 344         .fault          = ext4_dax_fault,
 345         .huge_fault     = ext4_dax_huge_fault,
 346         .page_mkwrite   = ext4_dax_fault,
 347         .pfn_mkwrite    = ext4_dax_fault,
 348 };
 349 #else
 350 #define ext4_dax_vm_ops ext4_file_vm_ops
 351 #endif
 352
 353 static const struct vm_operations_struct ext4_file_vm_ops = {
 354         .fault          = ext4_filemap_fault,
 355         .map_pages      = filemap_map_pages,
 356         .page_mkwrite   = ext4_page_mkwrite,
 357 };
 358
 359 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 360 {
 361         struct inode *inode = file->f_mapping->host;
 362
 363         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 364                 return -EIO;
 365
 366         file_accessed(file);
 367         if (IS_DAX(file_inode(file))) {
 368                 vma->vm_ops = &ext4_dax_vm_ops;
 369                 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 370         } else {
 371                 vma->vm_ops = &ext4_file_vm_ops;
 372         }
 373         return 0;
 374 }
 375
 376 static int ext4_file_open(struct inode * inode, struct file * filp)
 377 {
 378         struct super_block *sb = inode->i_sb;
 379         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 380         struct vfsmount *mnt = filp->f_path.mnt;
 381         struct dentry *dir;
 382         struct path path;
 383         char buf[64], *cp;
 384         int ret;
 385
 386         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 387                 return -EIO;
 388
 389         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 390                      !sb_rdonly(sb))) {
 391                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 392                 /*
 393                  * Sample where the filesystem has been mounted and
 394                  * store it in the superblock for sysadmin convenience
 395                  * when trying to sort through large numbers of block
 396                  * devices or filesystem images.
 397                  */
 398                 memset(buf, 0, sizeof(buf));
 399                 path.mnt = mnt;
 400                 path.dentry = mnt->mnt_root;
 401                 cp = d_path(&path, buf, sizeof(buf));
 402                 if (!IS_ERR(cp)) {
 403                         handle_t *handle;
 404                         int err;
 405
 406                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 407                         if (IS_ERR(handle))
 408                                 return PTR_ERR(handle);
 409                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 410                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 411                         if (err) {
 412                                 ext4_journal_stop(handle);
 413                                 return err;
 414                         }
 415                         strlcpy(sbi->s_es->s_last_mounted, cp,
 416                                 sizeof(sbi->s_es->s_last_mounted));
 417                         ext4_handle_dirty_super(handle, sb);
 418                         ext4_journal_stop(handle);
 419                 }
 420         }
 421         if (ext4_encrypted_inode(inode)) {
 422                 ret = fscrypt_get_encryption_info(inode);
 423                 if (ret)
 424                         return -EACCES;
 425                 if (!fscrypt_has_encryption_key(inode))
 426                         return -ENOKEY;
 427         }
 428
 429         dir = dget_parent(file_dentry(filp));
 430         if (ext4_encrypted_inode(d_inode(dir)) &&
 431                         !fscrypt_has_permitted_context(d_inode(dir), inode)) {
 432                 ext4_warning(inode->i_sb,
 433                              "Inconsistent encryption contexts: %lu/%lu",
 434                              (unsigned long) d_inode(dir)->i_ino,
 435                              (unsigned long) inode->i_ino);
 436                 dput(dir);
 437                 return -EPERM;
 438         }
 439         dput(dir);
 440         /*
 441          * Set up the jbd2_inode if we are opening the inode for
 442          * writing and the journal is present
 443          */
 444         if (filp->f_mode & FMODE_WRITE) {
 445                 ret = ext4_inode_attach_jinode(inode);
 446                 if (ret < 0)
 447                         return ret;
 448         }
 449
 450         filp->f_mode |= FMODE_NOWAIT;
 451         return dquot_file_open(inode, filp);
 452 }
 453
 454 /*
 455  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 456  * file rather than ext4_ext_walk_space() because we can introduce
 457  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 458  * function.  When extent status tree has been fully implemented, it will
 459  * track all extent status for a file and we can directly use it to
 460  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 461  */
 462
 463 /*
 464  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 465  * lookup page cache to check whether or not there has some data between
 466  * [startoff, endoff] because, if this range contains an unwritten extent,
 467  * we determine this extent as a data or a hole according to whether the
 468  * page cache has data or not.
 469  */
 470 static int ext4_find_unwritten_pgoff(struct inode *inode,
 471                                      int whence,
 472                                      ext4_lblk_t end_blk,
 473                                      loff_t *offset)
 474 {
 475         struct pagevec pvec;
 476         unsigned int blkbits;
 477         pgoff_t index;
 478         pgoff_t end;
 479         loff_t endoff;
 480         loff_t startoff;
 481         loff_t lastoff;
 482         int found = 0;
 483
 484         blkbits = inode->i_sb->s_blocksize_bits;
 485         startoff = *offset;
 486         lastoff = startoff;
 487         endoff = (loff_t)end_blk << blkbits;
 488
 489         index = startoff >> PAGE_SHIFT;
 490         end = (endoff - 1) >> PAGE_SHIFT;
 491
 492         pagevec_init(&pvec, 0);
 493         do {
 494                 int i;
 495                 unsigned long nr_pages;
 496
 497                 nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
 498                                         &index, end);
 499                 if (nr_pages == 0)
 500                         break;
 501
 502                 for (i = 0; i < nr_pages; i++) {
 503                         struct page *page = pvec.pages[i];
 504                         struct buffer_head *bh, *head;
 505
 506                         /*
 507                          * If current offset is smaller than the page offset,
 508                          * there is a hole at this offset.
 509                          */
 510                         if (whence == SEEK_HOLE && lastoff < endoff &&
 511                             lastoff < page_offset(pvec.pages[i])) {
 512                                 found = 1;
 513                                 *offset = lastoff;
 514                                 goto out;
 515                         }
 516
 517                         lock_page(page);
 518
 519                         if (unlikely(page->mapping != inode->i_mapping)) {
 520                                 unlock_page(page);
 521                                 continue;
 522                         }
 523
 524                         if (!page_has_buffers(page)) {
 525                                 unlock_page(page);
 526                                 continue;
 527                         }
 528
 529                         if (page_has_buffers(page)) {
 530                                 lastoff = page_offset(page);
 531                                 bh = head = page_buffers(page);
 532                                 do {
 533                                         if (lastoff + bh->b_size <= startoff)
 534                                                 goto next;
 535                                         if (buffer_uptodate(bh) ||
 536                                             buffer_unwritten(bh)) {
 537                                                 if (whence == SEEK_DATA)
 538                                                         found = 1;
 539                                         } else {
 540                                                 if (whence == SEEK_HOLE)
 541                                                         found = 1;
 542                                         }
 543                                         if (found) {
 544                                                 *offset = max_t(loff_t,
 545                                                         startoff, lastoff);
 546                                                 unlock_page(page);
 547                                                 goto out;
 548                                         }
 549 next:
 550                                         lastoff += bh->b_size;
 551                                         bh = bh->b_this_page;
 552                                 } while (bh != head);
 553                         }
 554
 555                         lastoff = page_offset(page) + PAGE_SIZE;
 556                         unlock_page(page);
 557                 }
 558
 559                 pagevec_release(&pvec);
 560         } while (index <= end);
 561
 562         /* There are no pages upto endoff - that would be a hole in there. */
 563         if (whence == SEEK_HOLE && lastoff < endoff) {
 564                 found = 1;
 565                 *offset = lastoff;
 566         }
 567 out:
 568         pagevec_release(&pvec);
 569         return found;
 570 }
 571
 572 /*
 573  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 574  */
 575 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 576 {
 577         struct inode *inode = file->f_mapping->host;
 578         struct extent_status es;
 579         ext4_lblk_t start, last, end;
 580         loff_t dataoff, isize;
 581         int blkbits;
 582         int ret;
 583
 584         inode_lock(inode);
 585
 586         isize = i_size_read(inode);
 587         if (offset < 0 || offset >= isize) {
 588                 inode_unlock(inode);
 589                 return -ENXIO;
 590         }
 591
 592         blkbits = inode->i_sb->s_blocksize_bits;
 593         start = offset >> blkbits;
 594         last = start;
 595         end = isize >> blkbits;
 596         dataoff = offset;
 597
 598         do {
 599                 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
 600                 if (ret <= 0) {
 601                         /* No extent found -> no data */
 602                         if (ret == 0)
 603                                 ret = -ENXIO;
 604                         inode_unlock(inode);
 605                         return ret;
 606                 }
 607
 608                 last = es.es_lblk;
 609                 if (last != start)
 610                         dataoff = (loff_t)last << blkbits;
 611                 if (!ext4_es_is_unwritten(&es))
 612                         break;
 613
 614                 /*
 615                  * If there is a unwritten extent at this offset,
 616                  * it will be as a data or a hole according to page
 617                  * cache that has data or not.
 618                  */
 619                 if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 620                                               es.es_lblk + es.es_len, &dataoff))
 621                         break;
 622                 last += es.es_len;
 623                 dataoff = (loff_t)last << blkbits;
 624                 cond_resched();
 625         } while (last <= end);
 626
 627         inode_unlock(inode);
 628
 629         if (dataoff > isize)
 630                 return -ENXIO;
 631
 632         return vfs_setpos(file, dataoff, maxsize);
 633 }
 634
 635 /*
 636  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 637  */
 638 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 639 {
 640         struct inode *inode = file->f_mapping->host;
 641         struct extent_status es;
 642         ext4_lblk_t start, last, end;
 643         loff_t holeoff, isize;
 644         int blkbits;
 645         int ret;
 646
 647         inode_lock(inode);
 648
 649         isize = i_size_read(inode);
 650         if (offset < 0 || offset >= isize) {
 651                 inode_unlock(inode);
 652                 return -ENXIO;
 653         }
 654
 655         blkbits = inode->i_sb->s_blocksize_bits;
 656         start = offset >> blkbits;
 657         last = start;
 658         end = isize >> blkbits;
 659         holeoff = offset;
 660
 661         do {
 662                 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
 663                 if (ret < 0) {
 664                         inode_unlock(inode);
 665                         return ret;
 666                 }
 667                 /* Found a hole? */
 668                 if (ret == 0 || es.es_lblk > last) {
 669                         if (last != start)
 670                                 holeoff = (loff_t)last << blkbits;
 671                         break;
 672                 }
 673                 /*
 674                  * If there is a unwritten extent at this offset,
 675                  * it will be as a data or a hole according to page
 676                  * cache that has data or not.
 677                  */
 678                 if (ext4_es_is_unwritten(&es) &&
 679                     ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 680                                               last + es.es_len, &holeoff))
 681                         break;
 682
 683                 last += es.es_len;
 684                 holeoff = (loff_t)last << blkbits;
 685                 cond_resched();
 686         } while (last <= end);
 687
 688         inode_unlock(inode);
 689
 690         if (holeoff > isize)
 691                 holeoff = isize;
 692
 693         return vfs_setpos(file, holeoff, maxsize);
 694 }
 695
 696 /*
 697  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 698  * by calling generic_file_llseek_size() with the appropriate maxbytes
 699  * value for each.
 700  */
 701 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 702 {
 703         struct inode *inode = file->f_mapping->host;
 704         loff_t maxbytes;
 705
 706         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 707                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 708         else
 709                 maxbytes = inode->i_sb->s_maxbytes;
 710
 711         switch (whence) {
 712         case SEEK_SET:
 713         case SEEK_CUR:
 714         case SEEK_END:
 715                 return generic_file_llseek_size(file, offset, whence,
 716                                                 maxbytes, i_size_read(inode));
 717         case SEEK_DATA:
 718                 return ext4_seek_data(file, offset, maxbytes);
 719         case SEEK_HOLE:
 720                 return ext4_seek_hole(file, offset, maxbytes);
 721         }
 722
 723         return -EINVAL;
 724 }
 725
 726 const struct file_operations ext4_file_operations = {
 727         .llseek         = ext4_llseek,
 728         .read_iter      = ext4_file_read_iter,
 729         .write_iter     = ext4_file_write_iter,
 730         .unlocked_ioctl = ext4_ioctl,
 731 #ifdef CONFIG_COMPAT
 732         .compat_ioctl   = ext4_compat_ioctl,
 733 #endif
 734         .mmap           = ext4_file_mmap,
 735         .open           = ext4_file_open,
 736         .release        = ext4_release_file,
 737         .fsync          = ext4_sync_file,
 738         .get_unmapped_area = thp_get_unmapped_area,
 739         .splice_read    = generic_file_splice_read,
 740         .splice_write   = iter_file_splice_write,
 741         .fallocate      = ext4_fallocate,
 742 };
 743
 744 const struct inode_operations ext4_file_inode_operations = {
 745         .setattr        = ext4_setattr,
 746         .getattr        = ext4_file_getattr,
 747         .listxattr      = ext4_listxattr,
 748         .get_acl        = ext4_get_acl,
 749         .set_acl        = ext4_set_acl,
 750         .fiemap         = ext4_fiemap,
 751 };
 752