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         if (!inode_trylock_shared(inode)) {
  41                 if (iocb->ki_flags & IOCB_NOWAIT)
  42                         return -EAGAIN;
  43                 inode_lock_shared(inode);
  44         }
  45         /*
  46          * Recheck under inode lock - at this point we are sure it cannot
  47          * change anymore
  48          */
  49         if (!IS_DAX(inode)) {
  50                 inode_unlock_shared(inode);
  51                 /* Fallback to buffered IO in case we cannot support DAX */
  52                 return generic_file_read_iter(iocb, to);
  53         }
  54         ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
  55         inode_unlock_shared(inode);
  56
  57         file_accessed(iocb->ki_filp);
  58         return ret;
  59 }
  60 #endif
  61
  62 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  63 {
  64         if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb))))
  65                 return -EIO;
  66
  67         if (!iov_iter_count(to))
  68                 return 0; /* skip atime */
  69
  70 #ifdef CONFIG_FS_DAX
  71         if (IS_DAX(file_inode(iocb->ki_filp)))
  72                 return ext4_dax_read_iter(iocb, to);
  73 #endif
  74         return generic_file_read_iter(iocb, to);
  75 }
  76
  77 /*
  78  * Called when an inode is released. Note that this is different
  79  * from ext4_file_open: open gets called at every open, but release
  80  * gets called only when /all/ the files are closed.
  81  */
  82 static int ext4_release_file(struct inode *inode, struct file *filp)
  83 {
  84         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
  85                 ext4_alloc_da_blocks(inode);
  86                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
  87         }
  88         /* if we are the last writer on the inode, drop the block reservation */
  89         if ((filp->f_mode & FMODE_WRITE) &&
  90                         (atomic_read(&inode->i_writecount) == 1) &&
  91                         !EXT4_I(inode)->i_reserved_data_blocks)
  92         {
  93                 down_write(&EXT4_I(inode)->i_data_sem);
  94                 ext4_discard_preallocations(inode);
  95                 up_write(&EXT4_I(inode)->i_data_sem);
  96         }
  97         if (is_dx(inode) && filp->private_data)
  98                 ext4_htree_free_dir_info(filp->private_data);
  99
 100         return 0;
 101 }
 102
 103 static void ext4_unwritten_wait(struct inode *inode)
 104 {
 105         wait_queue_head_t *wq = ext4_ioend_wq(inode);
 106
 107         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
 108 }
 109
 110 /*
 111  * This tests whether the IO in question is block-aligned or not.
 112  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 113  * are converted to written only after the IO is complete.  Until they are
 114  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 115  * it needs to zero out portions of the start and/or end block.  If 2 AIO
 116  * threads are at work on the same unwritten block, they must be synchronized
 117  * or one thread will zero the other's data, causing corruption.
 118  */
 119 static int
 120 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
 121 {
 122         struct super_block *sb = inode->i_sb;
 123         int blockmask = sb->s_blocksize - 1;
 124
 125         if (pos >= i_size_read(inode))
 126                 return 0;
 127
 128         if ((pos | iov_iter_alignment(from)) & blockmask)
 129                 return 1;
 130
 131         return 0;
 132 }
 133
 134 /* Is IO overwriting allocated and initialized blocks? */
 135 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
 136 {
 137         struct ext4_map_blocks map;
 138         unsigned int blkbits = inode->i_blkbits;
 139         int err, blklen;
 140
 141         if (pos + len > i_size_read(inode))
 142                 return false;
 143
 144         map.m_lblk = pos >> blkbits;
 145         map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
 146         blklen = map.m_len;
 147
 148         err = ext4_map_blocks(NULL, inode, &map, 0);
 149         /*
 150          * 'err==len' means that all of the blocks have been preallocated,
 151          * regardless of whether they have been initialized or not. To exclude
 152          * unwritten extents, we need to check m_flags.
 153          */
 154         return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
 155 }
 156
 157 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
 158 {
 159         struct inode *inode = file_inode(iocb->ki_filp);
 160         ssize_t ret;
 161
 162         ret = generic_write_checks(iocb, from);
 163         if (ret <= 0)
 164                 return ret;
 165         /*
 166          * If we have encountered a bitmap-format file, the size limit
 167          * is smaller than s_maxbytes, which is for extent-mapped files.
 168          */
 169         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 170                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 171
 172                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
 173                         return -EFBIG;
 174                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 175         }
 176         return iov_iter_count(from);
 177 }
 178
 179 #ifdef CONFIG_FS_DAX
 180 static ssize_t
 181 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 182 {
 183         struct inode *inode = file_inode(iocb->ki_filp);
 184         ssize_t ret;
 185
 186         if (!inode_trylock(inode)) {
 187                 if (iocb->ki_flags & IOCB_NOWAIT)
 188                         return -EAGAIN;
 189                 inode_lock(inode);
 190         }
 191         ret = ext4_write_checks(iocb, from);
 192         if (ret <= 0)
 193                 goto out;
 194         ret = file_remove_privs(iocb->ki_filp);
 195         if (ret)
 196                 goto out;
 197         ret = file_update_time(iocb->ki_filp);
 198         if (ret)
 199                 goto out;
 200
 201         ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 202 out:
 203         inode_unlock(inode);
 204         if (ret > 0)
 205                 ret = generic_write_sync(iocb, ret);
 206         return ret;
 207 }
 208 #endif
 209
 210 static ssize_t
 211 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 212 {
 213         struct inode *inode = file_inode(iocb->ki_filp);
 214         int o_direct = iocb->ki_flags & IOCB_DIRECT;
 215         int unaligned_aio = 0;
 216         int overwrite = 0;
 217         ssize_t ret;
 218
 219         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 220                 return -EIO;
 221
 222 #ifdef CONFIG_FS_DAX
 223         if (IS_DAX(inode))
 224                 return ext4_dax_write_iter(iocb, from);
 225 #endif
 226
 227         if (!inode_trylock(inode)) {
 228                 if (iocb->ki_flags & IOCB_NOWAIT)
 229                         return -EAGAIN;
 230                 inode_lock(inode);
 231         }
 232
 233         ret = ext4_write_checks(iocb, from);
 234         if (ret <= 0)
 235                 goto out;
 236
 237         /*
 238          * Unaligned direct AIO must be serialized among each other as zeroing
 239          * of partial blocks of two competing unaligned AIOs can result in data
 240          * corruption.
 241          */
 242         if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
 243             !is_sync_kiocb(iocb) &&
 244             ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
 245                 unaligned_aio = 1;
 246                 ext4_unwritten_wait(inode);
 247         }
 248
 249         iocb->private = &overwrite;
 250         /* Check whether we do a DIO overwrite or not */
 251         if (o_direct && !unaligned_aio) {
 252                 if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
 253                         if (ext4_should_dioread_nolock(inode))
 254                                 overwrite = 1;
 255                 } else if (iocb->ki_flags & IOCB_NOWAIT) {
 256                         ret = -EAGAIN;
 257                         goto out;
 258                 }
 259         }
 260
 261         ret = __generic_file_write_iter(iocb, from);
 262         inode_unlock(inode);
 263
 264         if (ret > 0)
 265                 ret = generic_write_sync(iocb, ret);
 266
 267         return ret;
 268
 269 out:
 270         inode_unlock(inode);
 271         return ret;
 272 }
 273
 274 #ifdef CONFIG_FS_DAX
 275 static int ext4_dax_huge_fault(struct vm_fault *vmf,
 276                 enum page_entry_size pe_size)
 277 {
 278         int result;
 279         handle_t *handle = NULL;
 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                 down_read(&EXT4_I(inode)->i_mmap_sem);
 288                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 289                                                EXT4_DATA_TRANS_BLOCKS(sb));
 290         } else {
 291                 down_read(&EXT4_I(inode)->i_mmap_sem);
 292         }
 293         if (!IS_ERR(handle))
 294                 result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops);
 295         else
 296                 result = VM_FAULT_SIGBUS;
 297         if (write) {
 298                 if (!IS_ERR(handle))
 299                         ext4_journal_stop(handle);
 300                 up_read(&EXT4_I(inode)->i_mmap_sem);
 301                 sb_end_pagefault(sb);
 302         } else {
 303                 up_read(&EXT4_I(inode)->i_mmap_sem);
 304         }
 305
 306         return result;
 307 }
 308
 309 static int ext4_dax_fault(struct vm_fault *vmf)
 310 {
 311         return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 312 }
 313
 314 /*
 315  * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_fault()
 316  * handler we check for races agaist truncate. Note that since we cycle through
 317  * i_mmap_sem, we are sure that also any hole punching that began before we
 318  * were called is finished by now and so if it included part of the file we
 319  * are working on, our pte will get unmapped and the check for pte_same() in
 320  * wp_pfn_shared() fails. Thus fault gets retried and things work out as
 321  * desired.
 322  */
 323 static int ext4_dax_pfn_mkwrite(struct vm_fault *vmf)
 324 {
 325         struct inode *inode = file_inode(vmf->vma->vm_file);
 326         struct super_block *sb = inode->i_sb;
 327         loff_t size;
 328         int ret;
 329
 330         sb_start_pagefault(sb);
 331         file_update_time(vmf->vma->vm_file);
 332         down_read(&EXT4_I(inode)->i_mmap_sem);
 333         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 334         if (vmf->pgoff >= size)
 335                 ret = VM_FAULT_SIGBUS;
 336         else
 337                 ret = dax_pfn_mkwrite(vmf);
 338         up_read(&EXT4_I(inode)->i_mmap_sem);
 339         sb_end_pagefault(sb);
 340
 341         return ret;
 342 }
 343
 344 static const struct vm_operations_struct ext4_dax_vm_ops = {
 345         .fault          = ext4_dax_fault,
 346         .huge_fault     = ext4_dax_huge_fault,
 347         .page_mkwrite   = ext4_dax_fault,
 348         .pfn_mkwrite    = ext4_dax_pfn_mkwrite,
 349 };
 350 #else
 351 #define ext4_dax_vm_ops ext4_file_vm_ops
 352 #endif
 353
 354 static const struct vm_operations_struct ext4_file_vm_ops = {
 355         .fault          = ext4_filemap_fault,
 356         .map_pages      = filemap_map_pages,
 357         .page_mkwrite   = ext4_page_mkwrite,
 358 };
 359
 360 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 361 {
 362         struct inode *inode = file->f_mapping->host;
 363
 364         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 365                 return -EIO;
 366
 367         file_accessed(file);
 368         if (IS_DAX(file_inode(file))) {
 369                 vma->vm_ops = &ext4_dax_vm_ops;
 370                 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 371         } else {
 372                 vma->vm_ops = &ext4_file_vm_ops;
 373         }
 374         return 0;
 375 }
 376
 377 static int ext4_file_open(struct inode * inode, struct file * filp)
 378 {
 379         struct super_block *sb = inode->i_sb;
 380         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 381         struct vfsmount *mnt = filp->f_path.mnt;
 382         struct dentry *dir;
 383         struct path path;
 384         char buf[64], *cp;
 385         int ret;
 386
 387         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 388                 return -EIO;
 389
 390         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 391                      !(sb->s_flags & MS_RDONLY))) {
 392                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 393                 /*
 394                  * Sample where the filesystem has been mounted and
 395                  * store it in the superblock for sysadmin convenience
 396                  * when trying to sort through large numbers of block
 397                  * devices or filesystem images.
 398                  */
 399                 memset(buf, 0, sizeof(buf));
 400                 path.mnt = mnt;
 401                 path.dentry = mnt->mnt_root;
 402                 cp = d_path(&path, buf, sizeof(buf));
 403                 if (!IS_ERR(cp)) {
 404                         handle_t *handle;
 405                         int err;
 406
 407                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 408                         if (IS_ERR(handle))
 409                                 return PTR_ERR(handle);
 410                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 411                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 412                         if (err) {
 413                                 ext4_journal_stop(handle);
 414                                 return err;
 415                         }
 416                         strlcpy(sbi->s_es->s_last_mounted, cp,
 417                                 sizeof(sbi->s_es->s_last_mounted));
 418                         ext4_handle_dirty_super(handle, sb);
 419                         ext4_journal_stop(handle);
 420                 }
 421         }
 422         if (ext4_encrypted_inode(inode)) {
 423                 ret = fscrypt_get_encryption_info(inode);
 424                 if (ret)
 425                         return -EACCES;
 426                 if (!fscrypt_has_encryption_key(inode))
 427                         return -ENOKEY;
 428         }
 429
 430         dir = dget_parent(file_dentry(filp));
 431         if (ext4_encrypted_inode(d_inode(dir)) &&
 432                         !fscrypt_has_permitted_context(d_inode(dir), inode)) {
 433                 ext4_warning(inode->i_sb,
 434                              "Inconsistent encryption contexts: %lu/%lu",
 435                              (unsigned long) d_inode(dir)->i_ino,
 436                              (unsigned long) inode->i_ino);
 437                 dput(dir);
 438                 return -EPERM;
 439         }
 440         dput(dir);
 441         /*
 442          * Set up the jbd2_inode if we are opening the inode for
 443          * writing and the journal is present
 444          */
 445         if (filp->f_mode & FMODE_WRITE) {
 446                 ret = ext4_inode_attach_jinode(inode);
 447                 if (ret < 0)
 448                         return ret;
 449         }
 450
 451         /* Set the flags to support nowait AIO */
 452         filp->f_mode |= FMODE_AIO_NOWAIT;
 453
 454         return dquot_file_open(inode, filp);
 455 }
 456
 457 /*
 458  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 459  * file rather than ext4_ext_walk_space() because we can introduce
 460  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 461  * function.  When extent status tree has been fully implemented, it will
 462  * track all extent status for a file and we can directly use it to
 463  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 464  */
 465
 466 /*
 467  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 468  * lookup page cache to check whether or not there has some data between
 469  * [startoff, endoff] because, if this range contains an unwritten extent,
 470  * we determine this extent as a data or a hole according to whether the
 471  * page cache has data or not.
 472  */
 473 static int ext4_find_unwritten_pgoff(struct inode *inode,
 474                                      int whence,
 475                                      ext4_lblk_t end_blk,
 476                                      loff_t *offset)
 477 {
 478         struct pagevec pvec;
 479         unsigned int blkbits;
 480         pgoff_t index;
 481         pgoff_t end;
 482         loff_t endoff;
 483         loff_t startoff;
 484         loff_t lastoff;
 485         int found = 0;
 486
 487         blkbits = inode->i_sb->s_blocksize_bits;
 488         startoff = *offset;
 489         lastoff = startoff;
 490         endoff = (loff_t)end_blk << blkbits;
 491
 492         index = startoff >> PAGE_SHIFT;
 493         end = (endoff - 1) >> PAGE_SHIFT;
 494
 495         pagevec_init(&pvec, 0);
 496         do {
 497                 int i, num;
 498                 unsigned long nr_pages;
 499
 500                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
 501                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 502                                           (pgoff_t)num);
 503                 if (nr_pages == 0)
 504                         break;
 505
 506                 for (i = 0; i < nr_pages; i++) {
 507                         struct page *page = pvec.pages[i];
 508                         struct buffer_head *bh, *head;
 509
 510                         /*
 511                          * If current offset is smaller than the page offset,
 512                          * there is a hole at this offset.
 513                          */
 514                         if (whence == SEEK_HOLE && lastoff < endoff &&
 515                             lastoff < page_offset(pvec.pages[i])) {
 516                                 found = 1;
 517                                 *offset = lastoff;
 518                                 goto out;
 519                         }
 520
 521                         if (page->index > end)
 522                                 goto out;
 523
 524                         lock_page(page);
 525
 526                         if (unlikely(page->mapping != inode->i_mapping)) {
 527                                 unlock_page(page);
 528                                 continue;
 529                         }
 530
 531                         if (!page_has_buffers(page)) {
 532                                 unlock_page(page);
 533                                 continue;
 534                         }
 535
 536                         if (page_has_buffers(page)) {
 537                                 lastoff = page_offset(page);
 538                                 bh = head = page_buffers(page);
 539                                 do {
 540                                         if (buffer_uptodate(bh) ||
 541                                             buffer_unwritten(bh)) {
 542                                                 if (whence == SEEK_DATA)
 543                                                         found = 1;
 544                                         } else {
 545                                                 if (whence == SEEK_HOLE)
 546                                                         found = 1;
 547                                         }
 548                                         if (found) {
 549                                                 *offset = max_t(loff_t,
 550                                                         startoff, lastoff);
 551                                                 unlock_page(page);
 552                                                 goto out;
 553                                         }
 554                                         lastoff += bh->b_size;
 555                                         bh = bh->b_this_page;
 556                                 } while (bh != head);
 557                         }
 558
 559                         lastoff = page_offset(page) + PAGE_SIZE;
 560                         unlock_page(page);
 561                 }
 562
 563                 /* The no. of pages is less than our desired, we are done. */
 564                 if (nr_pages < num)
 565                         break;
 566
 567                 index = pvec.pages[i - 1]->index + 1;
 568                 pagevec_release(&pvec);
 569         } while (index <= end);
 570
 571         if (whence == SEEK_HOLE && lastoff < endoff) {
 572                 found = 1;
 573                 *offset = lastoff;
 574         }
 575 out:
 576         pagevec_release(&pvec);
 577         return found;
 578 }
 579
 580 /*
 581  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 582  */
 583 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 584 {
 585         struct inode *inode = file->f_mapping->host;
 586         struct extent_status es;
 587         ext4_lblk_t start, last, end;
 588         loff_t dataoff, isize;
 589         int blkbits;
 590         int ret;
 591
 592         inode_lock(inode);
 593
 594         isize = i_size_read(inode);
 595         if (offset >= isize) {
 596                 inode_unlock(inode);
 597                 return -ENXIO;
 598         }
 599
 600         blkbits = inode->i_sb->s_blocksize_bits;
 601         start = offset >> blkbits;
 602         last = start;
 603         end = isize >> blkbits;
 604         dataoff = offset;
 605
 606         do {
 607                 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
 608                 if (ret <= 0) {
 609                         /* No extent found -> no data */
 610                         if (ret == 0)
 611                                 ret = -ENXIO;
 612                         inode_unlock(inode);
 613                         return ret;
 614                 }
 615
 616                 last = es.es_lblk;
 617                 if (last != start)
 618                         dataoff = (loff_t)last << blkbits;
 619                 if (!ext4_es_is_unwritten(&es))
 620                         break;
 621
 622                 /*
 623                  * If there is a unwritten extent at this offset,
 624                  * it will be as a data or a hole according to page
 625                  * cache that has data or not.
 626                  */
 627                 if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 628                                               es.es_lblk + es.es_len, &dataoff))
 629                         break;
 630                 last += es.es_len;
 631                 dataoff = (loff_t)last << blkbits;
 632                 cond_resched();
 633         } while (last <= end);
 634
 635         inode_unlock(inode);
 636
 637         if (dataoff > isize)
 638                 return -ENXIO;
 639
 640         return vfs_setpos(file, dataoff, maxsize);
 641 }
 642
 643 /*
 644  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 645  */
 646 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 647 {
 648         struct inode *inode = file->f_mapping->host;
 649         struct extent_status es;
 650         ext4_lblk_t start, last, end;
 651         loff_t holeoff, isize;
 652         int blkbits;
 653         int ret;
 654
 655         inode_lock(inode);
 656
 657         isize = i_size_read(inode);
 658         if (offset >= isize) {
 659                 inode_unlock(inode);
 660                 return -ENXIO;
 661         }
 662
 663         blkbits = inode->i_sb->s_blocksize_bits;
 664         start = offset >> blkbits;
 665         last = start;
 666         end = isize >> blkbits;
 667         holeoff = offset;
 668
 669         do {
 670                 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
 671                 if (ret < 0) {
 672                         inode_unlock(inode);
 673                         return ret;
 674                 }
 675                 /* Found a hole? */
 676                 if (ret == 0 || es.es_lblk > last) {
 677                         if (last != start)
 678                                 holeoff = (loff_t)last << blkbits;
 679                         break;
 680                 }
 681                 /*
 682                  * If there is a unwritten extent at this offset,
 683                  * it will be as a data or a hole according to page
 684                  * cache that has data or not.
 685                  */
 686                 if (ext4_es_is_unwritten(&es) &&
 687                     ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 688                                               last + es.es_len, &holeoff))
 689                         break;
 690
 691                 last += es.es_len;
 692                 holeoff = (loff_t)last << blkbits;
 693                 cond_resched();
 694         } while (last <= end);
 695
 696         inode_unlock(inode);
 697
 698         if (holeoff > isize)
 699                 holeoff = isize;
 700
 701         return vfs_setpos(file, holeoff, maxsize);
 702 }
 703
 704 /*
 705  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 706  * by calling generic_file_llseek_size() with the appropriate maxbytes
 707  * value for each.
 708  */
 709 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 710 {
 711         struct inode *inode = file->f_mapping->host;
 712         loff_t maxbytes;
 713
 714         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 715                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 716         else
 717                 maxbytes = inode->i_sb->s_maxbytes;
 718
 719         switch (whence) {
 720         case SEEK_SET:
 721         case SEEK_CUR:
 722         case SEEK_END:
 723                 return generic_file_llseek_size(file, offset, whence,
 724                                                 maxbytes, i_size_read(inode));
 725         case SEEK_DATA:
 726                 return ext4_seek_data(file, offset, maxbytes);
 727         case SEEK_HOLE:
 728                 return ext4_seek_hole(file, offset, maxbytes);
 729         }
 730
 731         return -EINVAL;
 732 }
 733
 734 const struct file_operations ext4_file_operations = {
 735         .llseek         = ext4_llseek,
 736         .read_iter      = ext4_file_read_iter,
 737         .write_iter     = ext4_file_write_iter,
 738         .unlocked_ioctl = ext4_ioctl,
 739 #ifdef CONFIG_COMPAT
 740         .compat_ioctl   = ext4_compat_ioctl,
 741 #endif
 742         .mmap           = ext4_file_mmap,
 743         .open           = ext4_file_open,
 744         .release        = ext4_release_file,
 745         .fsync          = ext4_sync_file,
 746         .get_unmapped_area = thp_get_unmapped_area,
 747         .splice_read    = generic_file_splice_read,
 748         .splice_write   = iter_file_splice_write,
 749         .fallocate      = ext4_fallocate,
 750 };
 751
 752 const struct inode_operations ext4_file_inode_operations = {
 753         .setattr        = ext4_setattr,
 754         .getattr        = ext4_file_getattr,
 755         .listxattr      = ext4_listxattr,
 756         .get_acl        = ext4_get_acl,
 757         .set_acl        = ext4_set_acl,
 758         .fiemap         = ext4_fiemap,
 759 };
 760