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/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 /*
  35  * Called when an inode is released. Note that this is different
  36  * from ext4_file_open: open gets called at every open, but release
  37  * gets called only when /all/ the files are closed.
  38  */
  39 static int ext4_release_file(struct inode *inode, struct file *filp)
  40 {
  41         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
  42                 ext4_alloc_da_blocks(inode);
  43                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
  44         }
  45         /* if we are the last writer on the inode, drop the block reservation */
  46         if ((filp->f_mode & FMODE_WRITE) &&
  47                         (atomic_read(&inode->i_writecount) == 1) &&
  48                         !EXT4_I(inode)->i_reserved_data_blocks)
  49         {
  50                 down_write(&EXT4_I(inode)->i_data_sem);
  51                 ext4_discard_preallocations(inode);
  52                 up_write(&EXT4_I(inode)->i_data_sem);
  53         }
  54         if (is_dx(inode) && filp->private_data)
  55                 ext4_htree_free_dir_info(filp->private_data);
  56
  57         return 0;
  58 }
  59
  60 static void ext4_unwritten_wait(struct inode *inode)
  61 {
  62         wait_queue_head_t *wq = ext4_ioend_wq(inode);
  63
  64         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
  65 }
  66
  67 /*
  68  * This tests whether the IO in question is block-aligned or not.
  69  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
  70  * are converted to written only after the IO is complete.  Until they are
  71  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
  72  * it needs to zero out portions of the start and/or end block.  If 2 AIO
  73  * threads are at work on the same unwritten block, they must be synchronized
  74  * or one thread will zero the other's data, causing corruption.
  75  */
  76 static int
  77 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
  78 {
  79         struct super_block *sb = inode->i_sb;
  80         int blockmask = sb->s_blocksize - 1;
  81
  82         if (pos >= i_size_read(inode))
  83                 return 0;
  84
  85         if ((pos | iov_iter_alignment(from)) & blockmask)
  86                 return 1;
  87
  88         return 0;
  89 }
  90
  91 static ssize_t
  92 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
  93 {
  94         struct file *file = iocb->ki_filp;
  95         struct inode *inode = file_inode(iocb->ki_filp);
  96         struct mutex *aio_mutex = NULL;
  97         struct blk_plug plug;
  98         int o_direct = iocb->ki_flags & IOCB_DIRECT;
  99         int overwrite = 0;
 100         ssize_t ret;
 101
 102         /*
 103          * Unaligned direct AIO must be serialized; see comment above
 104          * In the case of O_APPEND, assume that we must always serialize
 105          */
 106         if (o_direct &&
 107             ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
 108             !is_sync_kiocb(iocb) &&
 109             (iocb->ki_flags & IOCB_APPEND ||
 110              ext4_unaligned_aio(inode, from, iocb->ki_pos))) {
 111                 aio_mutex = ext4_aio_mutex(inode);
 112                 mutex_lock(aio_mutex);
 113                 ext4_unwritten_wait(inode);
 114         }
 115
 116         mutex_lock(&inode->i_mutex);
 117         ret = generic_write_checks(iocb, from);
 118         if (ret <= 0)
 119                 goto out;
 120
 121         /*
 122          * If we have encountered a bitmap-format file, the size limit
 123          * is smaller than s_maxbytes, which is for extent-mapped files.
 124          */
 125         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 126                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 127
 128                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) {
 129                         ret = -EFBIG;
 130                         goto out;
 131                 }
 132                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 133         }
 134
 135         iocb->private = &overwrite;
 136         if (o_direct) {
 137                 size_t length = iov_iter_count(from);
 138                 loff_t pos = iocb->ki_pos;
 139                 blk_start_plug(&plug);
 140
 141                 /* check whether we do a DIO overwrite or not */
 142                 if (ext4_should_dioread_nolock(inode) && !aio_mutex &&
 143                     !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
 144                         struct ext4_map_blocks map;
 145                         unsigned int blkbits = inode->i_blkbits;
 146                         int err, len;
 147
 148                         map.m_lblk = pos >> blkbits;
 149                         map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
 150                                 - map.m_lblk;
 151                         len = map.m_len;
 152
 153                         err = ext4_map_blocks(NULL, inode, &map, 0);
 154                         /*
 155                          * 'err==len' means that all of blocks has
 156                          * been preallocated no matter they are
 157                          * initialized or not.  For excluding
 158                          * unwritten extents, we need to check
 159                          * m_flags.  There are two conditions that
 160                          * indicate for initialized extents.  1) If we
 161                          * hit extent cache, EXT4_MAP_MAPPED flag is
 162                          * returned; 2) If we do a real lookup,
 163                          * non-flags are returned.  So we should check
 164                          * these two conditions.
 165                          */
 166                         if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
 167                                 overwrite = 1;
 168                 }
 169         }
 170
 171         ret = __generic_file_write_iter(iocb, from);
 172         mutex_unlock(&inode->i_mutex);
 173
 174         if (ret > 0) {
 175                 ssize_t err;
 176
 177                 err = generic_write_sync(file, iocb->ki_pos - ret, ret);
 178                 if (err < 0)
 179                         ret = err;
 180         }
 181         if (o_direct)
 182                 blk_finish_plug(&plug);
 183
 184         if (aio_mutex)
 185                 mutex_unlock(aio_mutex);
 186         return ret;
 187
 188 out:
 189         mutex_unlock(&inode->i_mutex);
 190         if (aio_mutex)
 191                 mutex_unlock(aio_mutex);
 192         return ret;
 193 }
 194
 195 #ifdef CONFIG_FS_DAX
 196 static void ext4_end_io_unwritten(struct buffer_head *bh, int uptodate)
 197 {
 198         struct inode *inode = bh->b_assoc_map->host;
 199         /* XXX: breaks on 32-bit > 16TB. Is that even supported? */
 200         loff_t offset = (loff_t)(uintptr_t)bh->b_private << inode->i_blkbits;
 201         int err;
 202         if (!uptodate)
 203                 return;
 204         WARN_ON(!buffer_unwritten(bh));
 205         err = ext4_convert_unwritten_extents(NULL, inode, offset, bh->b_size);
 206 }
 207
 208 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 209 {
 210         int result;
 211         handle_t *handle = NULL;
 212         struct inode *inode = file_inode(vma->vm_file);
 213         struct super_block *sb = inode->i_sb;
 214         bool write = vmf->flags & FAULT_FLAG_WRITE;
 215
 216         if (write) {
 217                 sb_start_pagefault(sb);
 218                 file_update_time(vma->vm_file);
 219                 down_read(&EXT4_I(inode)->i_mmap_sem);
 220                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 221                                                 EXT4_DATA_TRANS_BLOCKS(sb));
 222         } else
 223                 down_read(&EXT4_I(inode)->i_mmap_sem);
 224
 225         if (IS_ERR(handle))
 226                 result = VM_FAULT_SIGBUS;
 227         else
 228                 result = __dax_fault(vma, vmf, ext4_get_block_dax,
 229                                                 ext4_end_io_unwritten);
 230
 231         if (write) {
 232                 if (!IS_ERR(handle))
 233                         ext4_journal_stop(handle);
 234                 up_read(&EXT4_I(inode)->i_mmap_sem);
 235                 sb_end_pagefault(sb);
 236         } else
 237                 up_read(&EXT4_I(inode)->i_mmap_sem);
 238
 239         return result;
 240 }
 241
 242 static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
 243                                                 pmd_t *pmd, unsigned int flags)
 244 {
 245         int result;
 246         handle_t *handle = NULL;
 247         struct inode *inode = file_inode(vma->vm_file);
 248         struct super_block *sb = inode->i_sb;
 249         bool write = flags & FAULT_FLAG_WRITE;
 250
 251         if (write) {
 252                 sb_start_pagefault(sb);
 253                 file_update_time(vma->vm_file);
 254                 down_read(&EXT4_I(inode)->i_mmap_sem);
 255                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 256                                 ext4_chunk_trans_blocks(inode,
 257                                                         PMD_SIZE / PAGE_SIZE));
 258         } else
 259                 down_read(&EXT4_I(inode)->i_mmap_sem);
 260
 261         if (IS_ERR(handle))
 262                 result = VM_FAULT_SIGBUS;
 263         else
 264                 result = __dax_pmd_fault(vma, addr, pmd, flags,
 265                                 ext4_get_block_dax, ext4_end_io_unwritten);
 266
 267         if (write) {
 268                 if (!IS_ERR(handle))
 269                         ext4_journal_stop(handle);
 270                 up_read(&EXT4_I(inode)->i_mmap_sem);
 271                 sb_end_pagefault(sb);
 272         } else
 273                 up_read(&EXT4_I(inode)->i_mmap_sem);
 274
 275         return result;
 276 }
 277
 278 static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 279 {
 280         int err;
 281         struct inode *inode = file_inode(vma->vm_file);
 282
 283         sb_start_pagefault(inode->i_sb);
 284         file_update_time(vma->vm_file);
 285         down_read(&EXT4_I(inode)->i_mmap_sem);
 286         err = __dax_mkwrite(vma, vmf, ext4_get_block_dax,
 287                             ext4_end_io_unwritten);
 288         up_read(&EXT4_I(inode)->i_mmap_sem);
 289         sb_end_pagefault(inode->i_sb);
 290
 291         return err;
 292 }
 293
 294 /*
 295  * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_mkwrite()
 296  * handler we check for races agaist truncate. Note that since we cycle through
 297  * i_mmap_sem, we are sure that also any hole punching that began before we
 298  * were called is finished by now and so if it included part of the file we
 299  * are working on, our pte will get unmapped and the check for pte_same() in
 300  * wp_pfn_shared() fails. Thus fault gets retried and things work out as
 301  * desired.
 302  */
 303 static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
 304                                 struct vm_fault *vmf)
 305 {
 306         struct inode *inode = file_inode(vma->vm_file);
 307         struct super_block *sb = inode->i_sb;
 308         int ret = VM_FAULT_NOPAGE;
 309         loff_t size;
 310
 311         sb_start_pagefault(sb);
 312         file_update_time(vma->vm_file);
 313         down_read(&EXT4_I(inode)->i_mmap_sem);
 314         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 315         if (vmf->pgoff >= size)
 316                 ret = VM_FAULT_SIGBUS;
 317         up_read(&EXT4_I(inode)->i_mmap_sem);
 318         sb_end_pagefault(sb);
 319
 320         return ret;
 321 }
 322
 323 static const struct vm_operations_struct ext4_dax_vm_ops = {
 324         .fault          = ext4_dax_fault,
 325         .pmd_fault      = ext4_dax_pmd_fault,
 326         .page_mkwrite   = ext4_dax_mkwrite,
 327         .pfn_mkwrite    = ext4_dax_pfn_mkwrite,
 328 };
 329 #else
 330 #define ext4_dax_vm_ops ext4_file_vm_ops
 331 #endif
 332
 333 static const struct vm_operations_struct ext4_file_vm_ops = {
 334         .fault          = ext4_filemap_fault,
 335         .map_pages      = filemap_map_pages,
 336         .page_mkwrite   = ext4_page_mkwrite,
 337 };
 338
 339 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 340 {
 341         struct inode *inode = file->f_mapping->host;
 342
 343         if (ext4_encrypted_inode(inode)) {
 344                 int err = ext4_get_encryption_info(inode);
 345                 if (err)
 346                         return 0;
 347                 if (ext4_encryption_info(inode) == NULL)
 348                         return -ENOKEY;
 349         }
 350         file_accessed(file);
 351         if (IS_DAX(file_inode(file))) {
 352                 vma->vm_ops = &ext4_dax_vm_ops;
 353                 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 354         } else {
 355                 vma->vm_ops = &ext4_file_vm_ops;
 356         }
 357         return 0;
 358 }
 359
 360 static int ext4_file_open(struct inode * inode, struct file * filp)
 361 {
 362         struct super_block *sb = inode->i_sb;
 363         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 364         struct vfsmount *mnt = filp->f_path.mnt;
 365         struct path path;
 366         char buf[64], *cp;
 367         int ret;
 368
 369         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
 370                      !(sb->s_flags & MS_RDONLY))) {
 371                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 372                 /*
 373                  * Sample where the filesystem has been mounted and
 374                  * store it in the superblock for sysadmin convenience
 375                  * when trying to sort through large numbers of block
 376                  * devices or filesystem images.
 377                  */
 378                 memset(buf, 0, sizeof(buf));
 379                 path.mnt = mnt;
 380                 path.dentry = mnt->mnt_root;
 381                 cp = d_path(&path, buf, sizeof(buf));
 382                 if (!IS_ERR(cp)) {
 383                         handle_t *handle;
 384                         int err;
 385
 386                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 387                         if (IS_ERR(handle))
 388                                 return PTR_ERR(handle);
 389                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 390                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 391                         if (err) {
 392                                 ext4_journal_stop(handle);
 393                                 return err;
 394                         }
 395                         strlcpy(sbi->s_es->s_last_mounted, cp,
 396                                 sizeof(sbi->s_es->s_last_mounted));
 397                         ext4_handle_dirty_super(handle, sb);
 398                         ext4_journal_stop(handle);
 399                 }
 400         }
 401         if (ext4_encrypted_inode(inode)) {
 402                 ret = ext4_get_encryption_info(inode);
 403                 if (ret)
 404                         return -EACCES;
 405                 if (ext4_encryption_info(inode) == NULL)
 406                         return -ENOKEY;
 407         }
 408         /*
 409          * Set up the jbd2_inode if we are opening the inode for
 410          * writing and the journal is present
 411          */
 412         if (filp->f_mode & FMODE_WRITE) {
 413                 ret = ext4_inode_attach_jinode(inode);
 414                 if (ret < 0)
 415                         return ret;
 416         }
 417         return dquot_file_open(inode, filp);
 418 }
 419
 420 /*
 421  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
 422  * file rather than ext4_ext_walk_space() because we can introduce
 423  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
 424  * function.  When extent status tree has been fully implemented, it will
 425  * track all extent status for a file and we can directly use it to
 426  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
 427  */
 428
 429 /*
 430  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
 431  * lookup page cache to check whether or not there has some data between
 432  * [startoff, endoff] because, if this range contains an unwritten extent,
 433  * we determine this extent as a data or a hole according to whether the
 434  * page cache has data or not.
 435  */
 436 static int ext4_find_unwritten_pgoff(struct inode *inode,
 437                                      int whence,
 438                                      struct ext4_map_blocks *map,
 439                                      loff_t *offset)
 440 {
 441         struct pagevec pvec;
 442         unsigned int blkbits;
 443         pgoff_t index;
 444         pgoff_t end;
 445         loff_t endoff;
 446         loff_t startoff;
 447         loff_t lastoff;
 448         int found = 0;
 449
 450         blkbits = inode->i_sb->s_blocksize_bits;
 451         startoff = *offset;
 452         lastoff = startoff;
 453         endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
 454
 455         index = startoff >> PAGE_CACHE_SHIFT;
 456         end = endoff >> PAGE_CACHE_SHIFT;
 457
 458         pagevec_init(&pvec, 0);
 459         do {
 460                 int i, num;
 461                 unsigned long nr_pages;
 462
 463                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
 464                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
 465                                           (pgoff_t)num);
 466                 if (nr_pages == 0) {
 467                         if (whence == SEEK_DATA)
 468                                 break;
 469
 470                         BUG_ON(whence != SEEK_HOLE);
 471                         /*
 472                          * If this is the first time to go into the loop and
 473                          * offset is not beyond the end offset, it will be a
 474                          * hole at this offset
 475                          */
 476                         if (lastoff == startoff || lastoff < endoff)
 477                                 found = 1;
 478                         break;
 479                 }
 480
 481                 /*
 482                  * If this is the first time to go into the loop and
 483                  * offset is smaller than the first page offset, it will be a
 484                  * hole at this offset.
 485                  */
 486                 if (lastoff == startoff && whence == SEEK_HOLE &&
 487                     lastoff < page_offset(pvec.pages[0])) {
 488                         found = 1;
 489                         break;
 490                 }
 491
 492                 for (i = 0; i < nr_pages; i++) {
 493                         struct page *page = pvec.pages[i];
 494                         struct buffer_head *bh, *head;
 495
 496                         /*
 497                          * If the current offset is not beyond the end of given
 498                          * range, it will be a hole.
 499                          */
 500                         if (lastoff < endoff && whence == SEEK_HOLE &&
 501                             page->index > end) {
 502                                 found = 1;
 503                                 *offset = lastoff;
 504                                 goto out;
 505                         }
 506
 507                         lock_page(page);
 508
 509                         if (unlikely(page->mapping != inode->i_mapping)) {
 510                                 unlock_page(page);
 511                                 continue;
 512                         }
 513
 514                         if (!page_has_buffers(page)) {
 515                                 unlock_page(page);
 516                                 continue;
 517                         }
 518
 519                         if (page_has_buffers(page)) {
 520                                 lastoff = page_offset(page);
 521                                 bh = head = page_buffers(page);
 522                                 do {
 523                                         if (buffer_uptodate(bh) ||
 524                                             buffer_unwritten(bh)) {
 525                                                 if (whence == SEEK_DATA)
 526                                                         found = 1;
 527                                         } else {
 528                                                 if (whence == SEEK_HOLE)
 529                                                         found = 1;
 530                                         }
 531                                         if (found) {
 532                                                 *offset = max_t(loff_t,
 533                                                         startoff, lastoff);
 534                                                 unlock_page(page);
 535                                                 goto out;
 536                                         }
 537                                         lastoff += bh->b_size;
 538                                         bh = bh->b_this_page;
 539                                 } while (bh != head);
 540                         }
 541
 542                         lastoff = page_offset(page) + PAGE_SIZE;
 543                         unlock_page(page);
 544                 }
 545
 546                 /*
 547                  * The no. of pages is less than our desired, that would be a
 548                  * hole in there.
 549                  */
 550                 if (nr_pages < num && whence == SEEK_HOLE) {
 551                         found = 1;
 552                         *offset = lastoff;
 553                         break;
 554                 }
 555
 556                 index = pvec.pages[i - 1]->index + 1;
 557                 pagevec_release(&pvec);
 558         } while (index <= end);
 559
 560 out:
 561         pagevec_release(&pvec);
 562         return found;
 563 }
 564
 565 /*
 566  * ext4_seek_data() retrieves the offset for SEEK_DATA.
 567  */
 568 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 569 {
 570         struct inode *inode = file->f_mapping->host;
 571         struct ext4_map_blocks map;
 572         struct extent_status es;
 573         ext4_lblk_t start, last, end;
 574         loff_t dataoff, isize;
 575         int blkbits;
 576         int ret = 0;
 577
 578         mutex_lock(&inode->i_mutex);
 579
 580         isize = i_size_read(inode);
 581         if (offset >= isize) {
 582                 mutex_unlock(&inode->i_mutex);
 583                 return -ENXIO;
 584         }
 585
 586         blkbits = inode->i_sb->s_blocksize_bits;
 587         start = offset >> blkbits;
 588         last = start;
 589         end = isize >> blkbits;
 590         dataoff = offset;
 591
 592         do {
 593                 map.m_lblk = last;
 594                 map.m_len = end - last + 1;
 595                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 596                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 597                         if (last != start)
 598                                 dataoff = (loff_t)last << blkbits;
 599                         break;
 600                 }
 601
 602                 /*
 603                  * If there is a delay extent at this offset,
 604                  * it will be as a data.
 605                  */
 606                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 607                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 608                         if (last != start)
 609                                 dataoff = (loff_t)last << blkbits;
 610                         break;
 611                 }
 612
 613                 /*
 614                  * If there is a unwritten extent at this offset,
 615                  * it will be as a data or a hole according to page
 616                  * cache that has data or not.
 617                  */
 618                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 619                         int unwritten;
 620                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
 621                                                               &map, &dataoff);
 622                         if (unwritten)
 623                                 break;
 624                 }
 625
 626                 last++;
 627                 dataoff = (loff_t)last << blkbits;
 628         } while (last <= end);
 629
 630         mutex_unlock(&inode->i_mutex);
 631
 632         if (dataoff > isize)
 633                 return -ENXIO;
 634
 635         return vfs_setpos(file, dataoff, maxsize);
 636 }
 637
 638 /*
 639  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
 640  */
 641 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 642 {
 643         struct inode *inode = file->f_mapping->host;
 644         struct ext4_map_blocks map;
 645         struct extent_status es;
 646         ext4_lblk_t start, last, end;
 647         loff_t holeoff, isize;
 648         int blkbits;
 649         int ret = 0;
 650
 651         mutex_lock(&inode->i_mutex);
 652
 653         isize = i_size_read(inode);
 654         if (offset >= isize) {
 655                 mutex_unlock(&inode->i_mutex);
 656                 return -ENXIO;
 657         }
 658
 659         blkbits = inode->i_sb->s_blocksize_bits;
 660         start = offset >> blkbits;
 661         last = start;
 662         end = isize >> blkbits;
 663         holeoff = offset;
 664
 665         do {
 666                 map.m_lblk = last;
 667                 map.m_len = end - last + 1;
 668                 ret = ext4_map_blocks(NULL, inode, &map, 0);
 669                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
 670                         last += ret;
 671                         holeoff = (loff_t)last << blkbits;
 672                         continue;
 673                 }
 674
 675                 /*
 676                  * If there is a delay extent at this offset,
 677                  * we will skip this extent.
 678                  */
 679                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
 680                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
 681                         last = es.es_lblk + es.es_len;
 682                         holeoff = (loff_t)last << blkbits;
 683                         continue;
 684                 }
 685
 686                 /*
 687                  * If there is a unwritten extent at this offset,
 688                  * it will be as a data or a hole according to page
 689                  * cache that has data or not.
 690                  */
 691                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
 692                         int unwritten;
 693                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
 694                                                               &map, &holeoff);
 695                         if (!unwritten) {
 696                                 last += ret;
 697                                 holeoff = (loff_t)last << blkbits;
 698                                 continue;
 699                         }
 700                 }
 701
 702                 /* find a hole */
 703                 break;
 704         } while (last <= end);
 705
 706         mutex_unlock(&inode->i_mutex);
 707
 708         if (holeoff > isize)
 709                 holeoff = isize;
 710
 711         return vfs_setpos(file, holeoff, maxsize);
 712 }
 713
 714 /*
 715  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 716  * by calling generic_file_llseek_size() with the appropriate maxbytes
 717  * value for each.
 718  */
 719 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 720 {
 721         struct inode *inode = file->f_mapping->host;
 722         loff_t maxbytes;
 723
 724         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 725                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 726         else
 727                 maxbytes = inode->i_sb->s_maxbytes;
 728
 729         switch (whence) {
 730         case SEEK_SET:
 731         case SEEK_CUR:
 732         case SEEK_END:
 733                 return generic_file_llseek_size(file, offset, whence,
 734                                                 maxbytes, i_size_read(inode));
 735         case SEEK_DATA:
 736                 return ext4_seek_data(file, offset, maxbytes);
 737         case SEEK_HOLE:
 738                 return ext4_seek_hole(file, offset, maxbytes);
 739         }
 740
 741         return -EINVAL;
 742 }
 743
 744 const struct file_operations ext4_file_operations = {
 745         .llseek         = ext4_llseek,
 746         .read_iter      = generic_file_read_iter,
 747         .write_iter     = ext4_file_write_iter,
 748         .unlocked_ioctl = ext4_ioctl,
 749 #ifdef CONFIG_COMPAT
 750         .compat_ioctl   = ext4_compat_ioctl,
 751 #endif
 752         .mmap           = ext4_file_mmap,
 753         .open           = ext4_file_open,
 754         .release        = ext4_release_file,
 755         .fsync          = ext4_sync_file,
 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         .setxattr       = generic_setxattr,
 765         .getxattr       = generic_getxattr,
 766         .listxattr      = ext4_listxattr,
 767         .removexattr    = generic_removexattr,
 768         .get_acl        = ext4_get_acl,
 769         .set_acl        = ext4_set_acl,
 770         .fiemap         = ext4_fiemap,
 771 };
 772