1 /* 2 * linux/fs/ext4/file.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 * 9 * from 10 * 11 * linux/fs/minix/file.c 12 * 13 * Copyright (C) 1991, 1992 Linus Torvalds 14 * 15 * ext4 fs regular file handling primitives 16 * 17 * 64-bit file support on 64-bit platforms by Jakub Jelinek 18 * (jj@sunsite.ms.mff.cuni.cz) 19 */ 20 21 #include <linux/time.h> 22 #include <linux/fs.h> 23 #include <linux/mount.h> 24 #include <linux/path.h> 25 #include <linux/quotaops.h> 26 #include <linux/pagevec.h> 27 #include <linux/uio.h> 28 #include "ext4.h" 29 #include "ext4_jbd2.h" 30 #include "xattr.h" 31 #include "acl.h" 32 33 /* 34 * Called when an inode is released. Note that this is different 35 * from ext4_file_open: open gets called at every open, but release 36 * gets called only when /all/ the files are closed. 37 */ 38 static int ext4_release_file(struct inode *inode, struct file *filp) 39 { 40 if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) { 41 ext4_alloc_da_blocks(inode); 42 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE); 43 } 44 /* if we are the last writer on the inode, drop the block reservation */ 45 if ((filp->f_mode & FMODE_WRITE) && 46 (atomic_read(&inode->i_writecount) == 1) && 47 !EXT4_I(inode)->i_reserved_data_blocks) 48 { 49 down_write(&EXT4_I(inode)->i_data_sem); 50 ext4_discard_preallocations(inode); 51 up_write(&EXT4_I(inode)->i_data_sem); 52 } 53 if (is_dx(inode) && filp->private_data) 54 ext4_htree_free_dir_info(filp->private_data); 55 56 return 0; 57 } 58 59 static void ext4_unwritten_wait(struct inode *inode) 60 { 61 wait_queue_head_t *wq = ext4_ioend_wq(inode); 62 63 wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0)); 64 } 65 66 /* 67 * This tests whether the IO in question is block-aligned or not. 68 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they 69 * are converted to written only after the IO is complete. Until they are 70 * mapped, these blocks appear as holes, so dio_zero_block() will assume that 71 * it needs to zero out portions of the start and/or end block. If 2 AIO 72 * threads are at work on the same unwritten block, they must be synchronized 73 * or one thread will zero the other's data, causing corruption. 74 */ 75 static int 76 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos) 77 { 78 struct super_block *sb = inode->i_sb; 79 int blockmask = sb->s_blocksize - 1; 80 81 if (pos >= i_size_read(inode)) 82 return 0; 83 84 if ((pos | iov_iter_alignment(from)) & blockmask) 85 return 1; 86 87 return 0; 88 } 89 90 static ssize_t 91 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 92 { 93 struct file *file = iocb->ki_filp; 94 struct inode *inode = file_inode(iocb->ki_filp); 95 struct mutex *aio_mutex = NULL; 96 struct blk_plug plug; 97 int o_direct = iocb->ki_flags & IOCB_DIRECT; 98 int overwrite = 0; 99 ssize_t ret; 100 101 /* 102 * Unaligned direct AIO must be serialized; see comment above 103 * In the case of O_APPEND, assume that we must always serialize 104 */ 105 if (o_direct && 106 ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) && 107 !is_sync_kiocb(iocb) && 108 (iocb->ki_flags & IOCB_APPEND || 109 ext4_unaligned_aio(inode, from, iocb->ki_pos))) { 110 aio_mutex = ext4_aio_mutex(inode); 111 mutex_lock(aio_mutex); 112 ext4_unwritten_wait(inode); 113 } 114 115 mutex_lock(&inode->i_mutex); 116 ret = generic_write_checks(iocb, from); 117 if (ret <= 0) 118 goto out; 119 120 /* 121 * If we have encountered a bitmap-format file, the size limit 122 * is smaller than s_maxbytes, which is for extent-mapped files. 123 */ 124 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { 125 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 126 127 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) { 128 ret = -EFBIG; 129 goto out; 130 } 131 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos); 132 } 133 134 iocb->private = &overwrite; 135 if (o_direct) { 136 size_t length = iov_iter_count(from); 137 loff_t pos = iocb->ki_pos; 138 blk_start_plug(&plug); 139 140 /* check whether we do a DIO overwrite or not */ 141 if (ext4_should_dioread_nolock(inode) && !aio_mutex && 142 !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) { 143 struct ext4_map_blocks map; 144 unsigned int blkbits = inode->i_blkbits; 145 int err, len; 146 147 map.m_lblk = pos >> blkbits; 148 map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits) 149 - map.m_lblk; 150 len = map.m_len; 151 152 err = ext4_map_blocks(NULL, inode, &map, 0); 153 /* 154 * 'err==len' means that all of blocks has 155 * been preallocated no matter they are 156 * initialized or not. For excluding 157 * unwritten extents, we need to check 158 * m_flags. There are two conditions that 159 * indicate for initialized extents. 1) If we 160 * hit extent cache, EXT4_MAP_MAPPED flag is 161 * returned; 2) If we do a real lookup, 162 * non-flags are returned. So we should check 163 * these two conditions. 164 */ 165 if (err == len && (map.m_flags & EXT4_MAP_MAPPED)) 166 overwrite = 1; 167 } 168 } 169 170 ret = __generic_file_write_iter(iocb, from); 171 mutex_unlock(&inode->i_mutex); 172 173 if (ret > 0) { 174 ssize_t err; 175 176 err = generic_write_sync(file, iocb->ki_pos - ret, ret); 177 if (err < 0) 178 ret = err; 179 } 180 if (o_direct) 181 blk_finish_plug(&plug); 182 183 if (aio_mutex) 184 mutex_unlock(aio_mutex); 185 return ret; 186 187 out: 188 mutex_unlock(&inode->i_mutex); 189 if (aio_mutex) 190 mutex_unlock(aio_mutex); 191 return ret; 192 } 193 194 #ifdef CONFIG_FS_DAX 195 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 196 { 197 return dax_fault(vma, vmf, ext4_get_block); 198 /* Is this the right get_block? */ 199 } 200 201 static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) 202 { 203 return dax_mkwrite(vma, vmf, ext4_get_block); 204 } 205 206 static const struct vm_operations_struct ext4_dax_vm_ops = { 207 .fault = ext4_dax_fault, 208 .page_mkwrite = ext4_dax_mkwrite, 209 .pfn_mkwrite = dax_pfn_mkwrite, 210 }; 211 #else 212 #define ext4_dax_vm_ops ext4_file_vm_ops 213 #endif 214 215 static const struct vm_operations_struct ext4_file_vm_ops = { 216 .fault = filemap_fault, 217 .map_pages = filemap_map_pages, 218 .page_mkwrite = ext4_page_mkwrite, 219 }; 220 221 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) 222 { 223 struct inode *inode = file->f_mapping->host; 224 225 if (ext4_encrypted_inode(inode)) { 226 int err = ext4_generate_encryption_key(inode); 227 if (err) 228 return 0; 229 } 230 file_accessed(file); 231 if (IS_DAX(file_inode(file))) { 232 vma->vm_ops = &ext4_dax_vm_ops; 233 vma->vm_flags |= VM_MIXEDMAP; 234 } else { 235 vma->vm_ops = &ext4_file_vm_ops; 236 } 237 return 0; 238 } 239 240 static int ext4_file_open(struct inode * inode, struct file * filp) 241 { 242 struct super_block *sb = inode->i_sb; 243 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 244 struct vfsmount *mnt = filp->f_path.mnt; 245 struct path path; 246 char buf[64], *cp; 247 int ret; 248 249 if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) && 250 !(sb->s_flags & MS_RDONLY))) { 251 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED; 252 /* 253 * Sample where the filesystem has been mounted and 254 * store it in the superblock for sysadmin convenience 255 * when trying to sort through large numbers of block 256 * devices or filesystem images. 257 */ 258 memset(buf, 0, sizeof(buf)); 259 path.mnt = mnt; 260 path.dentry = mnt->mnt_root; 261 cp = d_path(&path, buf, sizeof(buf)); 262 if (!IS_ERR(cp)) { 263 handle_t *handle; 264 int err; 265 266 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1); 267 if (IS_ERR(handle)) 268 return PTR_ERR(handle); 269 BUFFER_TRACE(sbi->s_sbh, "get_write_access"); 270 err = ext4_journal_get_write_access(handle, sbi->s_sbh); 271 if (err) { 272 ext4_journal_stop(handle); 273 return err; 274 } 275 strlcpy(sbi->s_es->s_last_mounted, cp, 276 sizeof(sbi->s_es->s_last_mounted)); 277 ext4_handle_dirty_super(handle, sb); 278 ext4_journal_stop(handle); 279 } 280 } 281 /* 282 * Set up the jbd2_inode if we are opening the inode for 283 * writing and the journal is present 284 */ 285 if (filp->f_mode & FMODE_WRITE) { 286 ret = ext4_inode_attach_jinode(inode); 287 if (ret < 0) 288 return ret; 289 } 290 ret = dquot_file_open(inode, filp); 291 if (!ret && ext4_encrypted_inode(inode)) { 292 ret = ext4_generate_encryption_key(inode); 293 if (ret) 294 ret = -EACCES; 295 } 296 return ret; 297 } 298 299 /* 300 * Here we use ext4_map_blocks() to get a block mapping for a extent-based 301 * file rather than ext4_ext_walk_space() because we can introduce 302 * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same 303 * function. When extent status tree has been fully implemented, it will 304 * track all extent status for a file and we can directly use it to 305 * retrieve the offset for SEEK_DATA/SEEK_HOLE. 306 */ 307 308 /* 309 * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to 310 * lookup page cache to check whether or not there has some data between 311 * [startoff, endoff] because, if this range contains an unwritten extent, 312 * we determine this extent as a data or a hole according to whether the 313 * page cache has data or not. 314 */ 315 static int ext4_find_unwritten_pgoff(struct inode *inode, 316 int whence, 317 struct ext4_map_blocks *map, 318 loff_t *offset) 319 { 320 struct pagevec pvec; 321 unsigned int blkbits; 322 pgoff_t index; 323 pgoff_t end; 324 loff_t endoff; 325 loff_t startoff; 326 loff_t lastoff; 327 int found = 0; 328 329 blkbits = inode->i_sb->s_blocksize_bits; 330 startoff = *offset; 331 lastoff = startoff; 332 endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits; 333 334 index = startoff >> PAGE_CACHE_SHIFT; 335 end = endoff >> PAGE_CACHE_SHIFT; 336 337 pagevec_init(&pvec, 0); 338 do { 339 int i, num; 340 unsigned long nr_pages; 341 342 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE); 343 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index, 344 (pgoff_t)num); 345 if (nr_pages == 0) { 346 if (whence == SEEK_DATA) 347 break; 348 349 BUG_ON(whence != SEEK_HOLE); 350 /* 351 * If this is the first time to go into the loop and 352 * offset is not beyond the end offset, it will be a 353 * hole at this offset 354 */ 355 if (lastoff == startoff || lastoff < endoff) 356 found = 1; 357 break; 358 } 359 360 /* 361 * If this is the first time to go into the loop and 362 * offset is smaller than the first page offset, it will be a 363 * hole at this offset. 364 */ 365 if (lastoff == startoff && whence == SEEK_HOLE && 366 lastoff < page_offset(pvec.pages[0])) { 367 found = 1; 368 break; 369 } 370 371 for (i = 0; i < nr_pages; i++) { 372 struct page *page = pvec.pages[i]; 373 struct buffer_head *bh, *head; 374 375 /* 376 * If the current offset is not beyond the end of given 377 * range, it will be a hole. 378 */ 379 if (lastoff < endoff && whence == SEEK_HOLE && 380 page->index > end) { 381 found = 1; 382 *offset = lastoff; 383 goto out; 384 } 385 386 lock_page(page); 387 388 if (unlikely(page->mapping != inode->i_mapping)) { 389 unlock_page(page); 390 continue; 391 } 392 393 if (!page_has_buffers(page)) { 394 unlock_page(page); 395 continue; 396 } 397 398 if (page_has_buffers(page)) { 399 lastoff = page_offset(page); 400 bh = head = page_buffers(page); 401 do { 402 if (buffer_uptodate(bh) || 403 buffer_unwritten(bh)) { 404 if (whence == SEEK_DATA) 405 found = 1; 406 } else { 407 if (whence == SEEK_HOLE) 408 found = 1; 409 } 410 if (found) { 411 *offset = max_t(loff_t, 412 startoff, lastoff); 413 unlock_page(page); 414 goto out; 415 } 416 lastoff += bh->b_size; 417 bh = bh->b_this_page; 418 } while (bh != head); 419 } 420 421 lastoff = page_offset(page) + PAGE_SIZE; 422 unlock_page(page); 423 } 424 425 /* 426 * The no. of pages is less than our desired, that would be a 427 * hole in there. 428 */ 429 if (nr_pages < num && whence == SEEK_HOLE) { 430 found = 1; 431 *offset = lastoff; 432 break; 433 } 434 435 index = pvec.pages[i - 1]->index + 1; 436 pagevec_release(&pvec); 437 } while (index <= end); 438 439 out: 440 pagevec_release(&pvec); 441 return found; 442 } 443 444 /* 445 * ext4_seek_data() retrieves the offset for SEEK_DATA. 446 */ 447 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize) 448 { 449 struct inode *inode = file->f_mapping->host; 450 struct ext4_map_blocks map; 451 struct extent_status es; 452 ext4_lblk_t start, last, end; 453 loff_t dataoff, isize; 454 int blkbits; 455 int ret = 0; 456 457 mutex_lock(&inode->i_mutex); 458 459 isize = i_size_read(inode); 460 if (offset >= isize) { 461 mutex_unlock(&inode->i_mutex); 462 return -ENXIO; 463 } 464 465 blkbits = inode->i_sb->s_blocksize_bits; 466 start = offset >> blkbits; 467 last = start; 468 end = isize >> blkbits; 469 dataoff = offset; 470 471 do { 472 map.m_lblk = last; 473 map.m_len = end - last + 1; 474 ret = ext4_map_blocks(NULL, inode, &map, 0); 475 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) { 476 if (last != start) 477 dataoff = (loff_t)last << blkbits; 478 break; 479 } 480 481 /* 482 * If there is a delay extent at this offset, 483 * it will be as a data. 484 */ 485 ext4_es_find_delayed_extent_range(inode, last, last, &es); 486 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) { 487 if (last != start) 488 dataoff = (loff_t)last << blkbits; 489 break; 490 } 491 492 /* 493 * If there is a unwritten extent at this offset, 494 * it will be as a data or a hole according to page 495 * cache that has data or not. 496 */ 497 if (map.m_flags & EXT4_MAP_UNWRITTEN) { 498 int unwritten; 499 unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA, 500 &map, &dataoff); 501 if (unwritten) 502 break; 503 } 504 505 last++; 506 dataoff = (loff_t)last << blkbits; 507 } while (last <= end); 508 509 mutex_unlock(&inode->i_mutex); 510 511 if (dataoff > isize) 512 return -ENXIO; 513 514 return vfs_setpos(file, dataoff, maxsize); 515 } 516 517 /* 518 * ext4_seek_hole() retrieves the offset for SEEK_HOLE. 519 */ 520 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize) 521 { 522 struct inode *inode = file->f_mapping->host; 523 struct ext4_map_blocks map; 524 struct extent_status es; 525 ext4_lblk_t start, last, end; 526 loff_t holeoff, isize; 527 int blkbits; 528 int ret = 0; 529 530 mutex_lock(&inode->i_mutex); 531 532 isize = i_size_read(inode); 533 if (offset >= isize) { 534 mutex_unlock(&inode->i_mutex); 535 return -ENXIO; 536 } 537 538 blkbits = inode->i_sb->s_blocksize_bits; 539 start = offset >> blkbits; 540 last = start; 541 end = isize >> blkbits; 542 holeoff = offset; 543 544 do { 545 map.m_lblk = last; 546 map.m_len = end - last + 1; 547 ret = ext4_map_blocks(NULL, inode, &map, 0); 548 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) { 549 last += ret; 550 holeoff = (loff_t)last << blkbits; 551 continue; 552 } 553 554 /* 555 * If there is a delay extent at this offset, 556 * we will skip this extent. 557 */ 558 ext4_es_find_delayed_extent_range(inode, last, last, &es); 559 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) { 560 last = es.es_lblk + es.es_len; 561 holeoff = (loff_t)last << blkbits; 562 continue; 563 } 564 565 /* 566 * If there is a unwritten extent at this offset, 567 * it will be as a data or a hole according to page 568 * cache that has data or not. 569 */ 570 if (map.m_flags & EXT4_MAP_UNWRITTEN) { 571 int unwritten; 572 unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE, 573 &map, &holeoff); 574 if (!unwritten) { 575 last += ret; 576 holeoff = (loff_t)last << blkbits; 577 continue; 578 } 579 } 580 581 /* find a hole */ 582 break; 583 } while (last <= end); 584 585 mutex_unlock(&inode->i_mutex); 586 587 if (holeoff > isize) 588 holeoff = isize; 589 590 return vfs_setpos(file, holeoff, maxsize); 591 } 592 593 /* 594 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values 595 * by calling generic_file_llseek_size() with the appropriate maxbytes 596 * value for each. 597 */ 598 loff_t ext4_llseek(struct file *file, loff_t offset, int whence) 599 { 600 struct inode *inode = file->f_mapping->host; 601 loff_t maxbytes; 602 603 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) 604 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes; 605 else 606 maxbytes = inode->i_sb->s_maxbytes; 607 608 switch (whence) { 609 case SEEK_SET: 610 case SEEK_CUR: 611 case SEEK_END: 612 return generic_file_llseek_size(file, offset, whence, 613 maxbytes, i_size_read(inode)); 614 case SEEK_DATA: 615 return ext4_seek_data(file, offset, maxbytes); 616 case SEEK_HOLE: 617 return ext4_seek_hole(file, offset, maxbytes); 618 } 619 620 return -EINVAL; 621 } 622 623 const struct file_operations ext4_file_operations = { 624 .llseek = ext4_llseek, 625 .read_iter = generic_file_read_iter, 626 .write_iter = ext4_file_write_iter, 627 .unlocked_ioctl = ext4_ioctl, 628 #ifdef CONFIG_COMPAT 629 .compat_ioctl = ext4_compat_ioctl, 630 #endif 631 .mmap = ext4_file_mmap, 632 .open = ext4_file_open, 633 .release = ext4_release_file, 634 .fsync = ext4_sync_file, 635 .splice_read = generic_file_splice_read, 636 .splice_write = iter_file_splice_write, 637 .fallocate = ext4_fallocate, 638 }; 639 640 const struct inode_operations ext4_file_inode_operations = { 641 .setattr = ext4_setattr, 642 .getattr = ext4_getattr, 643 .setxattr = generic_setxattr, 644 .getxattr = generic_getxattr, 645 .listxattr = ext4_listxattr, 646 .removexattr = generic_removexattr, 647 .get_acl = ext4_get_acl, 648 .set_acl = ext4_set_acl, 649 .fiemap = ext4_fiemap, 650 }; 651 652