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/iomap.h> 25 #include <linux/mount.h> 26 #include <linux/path.h> 27 #include <linux/dax.h> 28 #include <linux/quotaops.h> 29 #include <linux/pagevec.h> 30 #include <linux/uio.h> 31 #include <linux/mman.h> 32 #include <linux/backing-dev.h> 33 #include "ext4.h" 34 #include "ext4_jbd2.h" 35 #include "xattr.h" 36 #include "acl.h" 37 #include "truncate.h" 38 39 /* 40 * Returns %true if the given DIO request should be attempted with DIO, or 41 * %false if it should fall back to buffered I/O. 42 * 43 * DIO isn't well specified; when it's unsupported (either due to the request 44 * being misaligned, or due to the file not supporting DIO at all), filesystems 45 * either fall back to buffered I/O or return EINVAL. For files that don't use 46 * any special features like encryption or verity, ext4 has traditionally 47 * returned EINVAL for misaligned DIO. iomap_dio_rw() uses this convention too. 48 * In this case, we should attempt the DIO, *not* fall back to buffered I/O. 49 * 50 * In contrast, in cases where DIO is unsupported due to ext4 features, ext4 51 * traditionally falls back to buffered I/O. 52 * 53 * This function implements the traditional ext4 behavior in all these cases. 54 */ 55 static bool ext4_should_use_dio(struct kiocb *iocb, struct iov_iter *iter) 56 { 57 struct inode *inode = file_inode(iocb->ki_filp); 58 u32 dio_align = ext4_dio_alignment(inode); 59 60 if (dio_align == 0) 61 return false; 62 63 if (dio_align == 1) 64 return true; 65 66 return IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), dio_align); 67 } 68 69 static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to) 70 { 71 ssize_t ret; 72 struct inode *inode = file_inode(iocb->ki_filp); 73 74 if (iocb->ki_flags & IOCB_NOWAIT) { 75 if (!inode_trylock_shared(inode)) 76 return -EAGAIN; 77 } else { 78 inode_lock_shared(inode); 79 } 80 81 if (!ext4_should_use_dio(iocb, to)) { 82 inode_unlock_shared(inode); 83 /* 84 * Fallback to buffered I/O if the operation being performed on 85 * the inode is not supported by direct I/O. The IOCB_DIRECT 86 * flag needs to be cleared here in order to ensure that the 87 * direct I/O path within generic_file_read_iter() is not 88 * taken. 89 */ 90 iocb->ki_flags &= ~IOCB_DIRECT; 91 return generic_file_read_iter(iocb, to); 92 } 93 94 ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL, 0, NULL, 0); 95 inode_unlock_shared(inode); 96 97 file_accessed(iocb->ki_filp); 98 return ret; 99 } 100 101 #ifdef CONFIG_FS_DAX 102 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) 103 { 104 struct inode *inode = file_inode(iocb->ki_filp); 105 ssize_t ret; 106 107 if (iocb->ki_flags & IOCB_NOWAIT) { 108 if (!inode_trylock_shared(inode)) 109 return -EAGAIN; 110 } else { 111 inode_lock_shared(inode); 112 } 113 /* 114 * Recheck under inode lock - at this point we are sure it cannot 115 * change anymore 116 */ 117 if (!IS_DAX(inode)) { 118 inode_unlock_shared(inode); 119 /* Fallback to buffered IO in case we cannot support DAX */ 120 return generic_file_read_iter(iocb, to); 121 } 122 ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops); 123 inode_unlock_shared(inode); 124 125 file_accessed(iocb->ki_filp); 126 return ret; 127 } 128 #endif 129 130 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 131 { 132 struct inode *inode = file_inode(iocb->ki_filp); 133 134 if (unlikely(ext4_forced_shutdown(inode->i_sb))) 135 return -EIO; 136 137 if (!iov_iter_count(to)) 138 return 0; /* skip atime */ 139 140 #ifdef CONFIG_FS_DAX 141 if (IS_DAX(inode)) 142 return ext4_dax_read_iter(iocb, to); 143 #endif 144 if (iocb->ki_flags & IOCB_DIRECT) 145 return ext4_dio_read_iter(iocb, to); 146 147 return generic_file_read_iter(iocb, to); 148 } 149 150 static ssize_t ext4_file_splice_read(struct file *in, loff_t *ppos, 151 struct pipe_inode_info *pipe, 152 size_t len, unsigned int flags) 153 { 154 struct inode *inode = file_inode(in); 155 156 if (unlikely(ext4_forced_shutdown(inode->i_sb))) 157 return -EIO; 158 return filemap_splice_read(in, ppos, pipe, len, flags); 159 } 160 161 /* 162 * Called when an inode is released. Note that this is different 163 * from ext4_file_open: open gets called at every open, but release 164 * gets called only when /all/ the files are closed. 165 */ 166 static int ext4_release_file(struct inode *inode, struct file *filp) 167 { 168 if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) { 169 ext4_alloc_da_blocks(inode); 170 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE); 171 } 172 /* if we are the last writer on the inode, drop the block reservation */ 173 if ((filp->f_mode & FMODE_WRITE) && 174 (atomic_read(&inode->i_writecount) == 1) && 175 !EXT4_I(inode)->i_reserved_data_blocks) { 176 down_write(&EXT4_I(inode)->i_data_sem); 177 ext4_discard_preallocations(inode); 178 up_write(&EXT4_I(inode)->i_data_sem); 179 } 180 if (is_dx(inode) && filp->private_data) 181 ext4_htree_free_dir_info(filp->private_data); 182 183 return 0; 184 } 185 186 /* 187 * This tests whether the IO in question is block-aligned or not. 188 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they 189 * are converted to written only after the IO is complete. Until they are 190 * mapped, these blocks appear as holes, so dio_zero_block() will assume that 191 * it needs to zero out portions of the start and/or end block. If 2 AIO 192 * threads are at work on the same unwritten block, they must be synchronized 193 * or one thread will zero the other's data, causing corruption. 194 */ 195 static bool 196 ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos) 197 { 198 struct super_block *sb = inode->i_sb; 199 unsigned long blockmask = sb->s_blocksize - 1; 200 201 if ((pos | iov_iter_alignment(from)) & blockmask) 202 return true; 203 204 return false; 205 } 206 207 static bool 208 ext4_extending_io(struct inode *inode, loff_t offset, size_t len) 209 { 210 if (offset + len > i_size_read(inode) || 211 offset + len > EXT4_I(inode)->i_disksize) 212 return true; 213 return false; 214 } 215 216 /* Is IO overwriting allocated or initialized blocks? */ 217 static bool ext4_overwrite_io(struct inode *inode, 218 loff_t pos, loff_t len, bool *unwritten) 219 { 220 struct ext4_map_blocks map; 221 unsigned int blkbits = inode->i_blkbits; 222 int err, blklen; 223 224 if (pos + len > i_size_read(inode)) 225 return false; 226 227 map.m_lblk = pos >> blkbits; 228 map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits); 229 blklen = map.m_len; 230 231 err = ext4_map_blocks(NULL, inode, &map, 0); 232 if (err != blklen) 233 return false; 234 /* 235 * 'err==len' means that all of the blocks have been preallocated, 236 * regardless of whether they have been initialized or not. We need to 237 * check m_flags to distinguish the unwritten extents. 238 */ 239 *unwritten = !(map.m_flags & EXT4_MAP_MAPPED); 240 return true; 241 } 242 243 static ssize_t ext4_generic_write_checks(struct kiocb *iocb, 244 struct iov_iter *from) 245 { 246 struct inode *inode = file_inode(iocb->ki_filp); 247 ssize_t ret; 248 249 if (unlikely(IS_IMMUTABLE(inode))) 250 return -EPERM; 251 252 ret = generic_write_checks(iocb, from); 253 if (ret <= 0) 254 return ret; 255 256 /* 257 * If we have encountered a bitmap-format file, the size limit 258 * is smaller than s_maxbytes, which is for extent-mapped files. 259 */ 260 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { 261 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 262 263 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) 264 return -EFBIG; 265 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos); 266 } 267 268 return iov_iter_count(from); 269 } 270 271 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from) 272 { 273 ssize_t ret, count; 274 275 count = ext4_generic_write_checks(iocb, from); 276 if (count <= 0) 277 return count; 278 279 ret = file_modified(iocb->ki_filp); 280 if (ret) 281 return ret; 282 return count; 283 } 284 285 static ssize_t ext4_buffered_write_iter(struct kiocb *iocb, 286 struct iov_iter *from) 287 { 288 ssize_t ret; 289 struct inode *inode = file_inode(iocb->ki_filp); 290 291 if (iocb->ki_flags & IOCB_NOWAIT) 292 return -EOPNOTSUPP; 293 294 inode_lock(inode); 295 ret = ext4_write_checks(iocb, from); 296 if (ret <= 0) 297 goto out; 298 299 ret = generic_perform_write(iocb, from); 300 301 out: 302 inode_unlock(inode); 303 if (unlikely(ret <= 0)) 304 return ret; 305 return generic_write_sync(iocb, ret); 306 } 307 308 static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset, 309 ssize_t written, ssize_t count) 310 { 311 handle_t *handle; 312 313 lockdep_assert_held_write(&inode->i_rwsem); 314 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); 315 if (IS_ERR(handle)) 316 return PTR_ERR(handle); 317 318 if (ext4_update_inode_size(inode, offset + written)) { 319 int ret = ext4_mark_inode_dirty(handle, inode); 320 if (unlikely(ret)) { 321 ext4_journal_stop(handle); 322 return ret; 323 } 324 } 325 326 if ((written == count) && inode->i_nlink) 327 ext4_orphan_del(handle, inode); 328 ext4_journal_stop(handle); 329 330 return written; 331 } 332 333 /* 334 * Clean up the inode after DIO or DAX extending write has completed and the 335 * inode size has been updated using ext4_handle_inode_extension(). 336 */ 337 static void ext4_inode_extension_cleanup(struct inode *inode, bool need_trunc) 338 { 339 lockdep_assert_held_write(&inode->i_rwsem); 340 if (need_trunc) { 341 ext4_truncate_failed_write(inode); 342 /* 343 * If the truncate operation failed early, then the inode may 344 * still be on the orphan list. In that case, we need to try 345 * remove the inode from the in-memory linked list. 346 */ 347 if (inode->i_nlink) 348 ext4_orphan_del(NULL, inode); 349 return; 350 } 351 /* 352 * If i_disksize got extended either due to writeback of delalloc 353 * blocks or extending truncate while the DIO was running we could fail 354 * to cleanup the orphan list in ext4_handle_inode_extension(). Do it 355 * now. 356 */ 357 if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) { 358 handle_t *handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); 359 360 if (IS_ERR(handle)) { 361 /* 362 * The write has successfully completed. Not much to 363 * do with the error here so just cleanup the orphan 364 * list and hope for the best. 365 */ 366 ext4_orphan_del(NULL, inode); 367 return; 368 } 369 ext4_orphan_del(handle, inode); 370 ext4_journal_stop(handle); 371 } 372 } 373 374 static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size, 375 int error, unsigned int flags) 376 { 377 loff_t pos = iocb->ki_pos; 378 struct inode *inode = file_inode(iocb->ki_filp); 379 380 if (!error && size && flags & IOMAP_DIO_UNWRITTEN) 381 error = ext4_convert_unwritten_extents(NULL, inode, pos, size); 382 if (error) 383 return error; 384 /* 385 * Note that EXT4_I(inode)->i_disksize can get extended up to 386 * inode->i_size while the I/O was running due to writeback of delalloc 387 * blocks. But the code in ext4_iomap_alloc() is careful to use 388 * zeroed/unwritten extents if this is possible; thus we won't leave 389 * uninitialized blocks in a file even if we didn't succeed in writing 390 * as much as we intended. Also we can race with truncate or write 391 * expanding the file so we have to be a bit careful here. 392 */ 393 if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize) && 394 pos + size <= i_size_read(inode)) 395 return size; 396 return ext4_handle_inode_extension(inode, pos, size, size); 397 } 398 399 static const struct iomap_dio_ops ext4_dio_write_ops = { 400 .end_io = ext4_dio_write_end_io, 401 }; 402 403 /* 404 * The intention here is to start with shared lock acquired then see if any 405 * condition requires an exclusive inode lock. If yes, then we restart the 406 * whole operation by releasing the shared lock and acquiring exclusive lock. 407 * 408 * - For unaligned_io we never take shared lock as it may cause data corruption 409 * when two unaligned IO tries to modify the same block e.g. while zeroing. 410 * 411 * - For extending writes case we don't take the shared lock, since it requires 412 * updating inode i_disksize and/or orphan handling with exclusive lock. 413 * 414 * - shared locking will only be true mostly with overwrites, including 415 * initialized blocks and unwritten blocks. For overwrite unwritten blocks 416 * we protect splitting extents by i_data_sem in ext4_inode_info, so we can 417 * also release exclusive i_rwsem lock. 418 * 419 * - Otherwise we will switch to exclusive i_rwsem lock. 420 */ 421 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from, 422 bool *ilock_shared, bool *extend, 423 bool *unwritten, int *dio_flags) 424 { 425 struct file *file = iocb->ki_filp; 426 struct inode *inode = file_inode(file); 427 loff_t offset; 428 size_t count; 429 ssize_t ret; 430 bool overwrite, unaligned_io; 431 432 restart: 433 ret = ext4_generic_write_checks(iocb, from); 434 if (ret <= 0) 435 goto out; 436 437 offset = iocb->ki_pos; 438 count = ret; 439 440 unaligned_io = ext4_unaligned_io(inode, from, offset); 441 *extend = ext4_extending_io(inode, offset, count); 442 overwrite = ext4_overwrite_io(inode, offset, count, unwritten); 443 444 /* 445 * Determine whether we need to upgrade to an exclusive lock. This is 446 * required to change security info in file_modified(), for extending 447 * I/O, any form of non-overwrite I/O, and unaligned I/O to unwritten 448 * extents (as partial block zeroing may be required). 449 * 450 * Note that unaligned writes are allowed under shared lock so long as 451 * they are pure overwrites. Otherwise, concurrent unaligned writes risk 452 * data corruption due to partial block zeroing in the dio layer, and so 453 * the I/O must occur exclusively. 454 */ 455 if (*ilock_shared && 456 ((!IS_NOSEC(inode) || *extend || !overwrite || 457 (unaligned_io && *unwritten)))) { 458 if (iocb->ki_flags & IOCB_NOWAIT) { 459 ret = -EAGAIN; 460 goto out; 461 } 462 inode_unlock_shared(inode); 463 *ilock_shared = false; 464 inode_lock(inode); 465 goto restart; 466 } 467 468 /* 469 * Now that locking is settled, determine dio flags and exclusivity 470 * requirements. We don't use DIO_OVERWRITE_ONLY because we enforce 471 * behavior already. The inode lock is already held exclusive if the 472 * write is non-overwrite or extending, so drain all outstanding dio and 473 * set the force wait dio flag. 474 */ 475 if (!*ilock_shared && (unaligned_io || *extend)) { 476 if (iocb->ki_flags & IOCB_NOWAIT) { 477 ret = -EAGAIN; 478 goto out; 479 } 480 if (unaligned_io && (!overwrite || *unwritten)) 481 inode_dio_wait(inode); 482 *dio_flags = IOMAP_DIO_FORCE_WAIT; 483 } 484 485 ret = file_modified(file); 486 if (ret < 0) 487 goto out; 488 489 return count; 490 out: 491 if (*ilock_shared) 492 inode_unlock_shared(inode); 493 else 494 inode_unlock(inode); 495 return ret; 496 } 497 498 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) 499 { 500 ssize_t ret; 501 handle_t *handle; 502 struct inode *inode = file_inode(iocb->ki_filp); 503 loff_t offset = iocb->ki_pos; 504 size_t count = iov_iter_count(from); 505 const struct iomap_ops *iomap_ops = &ext4_iomap_ops; 506 bool extend = false, unwritten = false; 507 bool ilock_shared = true; 508 int dio_flags = 0; 509 510 /* 511 * Quick check here without any i_rwsem lock to see if it is extending 512 * IO. A more reliable check is done in ext4_dio_write_checks() with 513 * proper locking in place. 514 */ 515 if (offset + count > i_size_read(inode)) 516 ilock_shared = false; 517 518 if (iocb->ki_flags & IOCB_NOWAIT) { 519 if (ilock_shared) { 520 if (!inode_trylock_shared(inode)) 521 return -EAGAIN; 522 } else { 523 if (!inode_trylock(inode)) 524 return -EAGAIN; 525 } 526 } else { 527 if (ilock_shared) 528 inode_lock_shared(inode); 529 else 530 inode_lock(inode); 531 } 532 533 /* Fallback to buffered I/O if the inode does not support direct I/O. */ 534 if (!ext4_should_use_dio(iocb, from)) { 535 if (ilock_shared) 536 inode_unlock_shared(inode); 537 else 538 inode_unlock(inode); 539 return ext4_buffered_write_iter(iocb, from); 540 } 541 542 /* 543 * Prevent inline data from being created since we are going to allocate 544 * blocks for DIO. We know the inode does not currently have inline data 545 * because ext4_should_use_dio() checked for it, but we have to clear 546 * the state flag before the write checks because a lock cycle could 547 * introduce races with other writers. 548 */ 549 ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA); 550 551 ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend, 552 &unwritten, &dio_flags); 553 if (ret <= 0) 554 return ret; 555 556 offset = iocb->ki_pos; 557 count = ret; 558 559 if (extend) { 560 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); 561 if (IS_ERR(handle)) { 562 ret = PTR_ERR(handle); 563 goto out; 564 } 565 566 ret = ext4_orphan_add(handle, inode); 567 if (ret) { 568 ext4_journal_stop(handle); 569 goto out; 570 } 571 572 ext4_journal_stop(handle); 573 } 574 575 if (ilock_shared && !unwritten) 576 iomap_ops = &ext4_iomap_overwrite_ops; 577 ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops, 578 dio_flags, NULL, 0); 579 if (ret == -ENOTBLK) 580 ret = 0; 581 if (extend) { 582 /* 583 * We always perform extending DIO write synchronously so by 584 * now the IO is completed and ext4_handle_inode_extension() 585 * was called. Cleanup the inode in case of error or race with 586 * writeback of delalloc blocks. 587 */ 588 WARN_ON_ONCE(ret == -EIOCBQUEUED); 589 ext4_inode_extension_cleanup(inode, ret < 0); 590 } 591 592 out: 593 if (ilock_shared) 594 inode_unlock_shared(inode); 595 else 596 inode_unlock(inode); 597 598 if (ret >= 0 && iov_iter_count(from)) { 599 ssize_t err; 600 loff_t endbyte; 601 602 offset = iocb->ki_pos; 603 err = ext4_buffered_write_iter(iocb, from); 604 if (err < 0) 605 return err; 606 607 /* 608 * We need to ensure that the pages within the page cache for 609 * the range covered by this I/O are written to disk and 610 * invalidated. This is in attempt to preserve the expected 611 * direct I/O semantics in the case we fallback to buffered I/O 612 * to complete off the I/O request. 613 */ 614 ret += err; 615 endbyte = offset + err - 1; 616 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping, 617 offset, endbyte); 618 if (!err) 619 invalidate_mapping_pages(iocb->ki_filp->f_mapping, 620 offset >> PAGE_SHIFT, 621 endbyte >> PAGE_SHIFT); 622 } 623 624 return ret; 625 } 626 627 #ifdef CONFIG_FS_DAX 628 static ssize_t 629 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) 630 { 631 ssize_t ret; 632 size_t count; 633 loff_t offset; 634 handle_t *handle; 635 bool extend = false; 636 struct inode *inode = file_inode(iocb->ki_filp); 637 638 if (iocb->ki_flags & IOCB_NOWAIT) { 639 if (!inode_trylock(inode)) 640 return -EAGAIN; 641 } else { 642 inode_lock(inode); 643 } 644 645 ret = ext4_write_checks(iocb, from); 646 if (ret <= 0) 647 goto out; 648 649 offset = iocb->ki_pos; 650 count = iov_iter_count(from); 651 652 if (offset + count > EXT4_I(inode)->i_disksize) { 653 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); 654 if (IS_ERR(handle)) { 655 ret = PTR_ERR(handle); 656 goto out; 657 } 658 659 ret = ext4_orphan_add(handle, inode); 660 if (ret) { 661 ext4_journal_stop(handle); 662 goto out; 663 } 664 665 extend = true; 666 ext4_journal_stop(handle); 667 } 668 669 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops); 670 671 if (extend) { 672 ret = ext4_handle_inode_extension(inode, offset, ret, count); 673 ext4_inode_extension_cleanup(inode, ret < (ssize_t)count); 674 } 675 out: 676 inode_unlock(inode); 677 if (ret > 0) 678 ret = generic_write_sync(iocb, ret); 679 return ret; 680 } 681 #endif 682 683 static ssize_t 684 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 685 { 686 struct inode *inode = file_inode(iocb->ki_filp); 687 688 if (unlikely(ext4_forced_shutdown(inode->i_sb))) 689 return -EIO; 690 691 #ifdef CONFIG_FS_DAX 692 if (IS_DAX(inode)) 693 return ext4_dax_write_iter(iocb, from); 694 #endif 695 if (iocb->ki_flags & IOCB_DIRECT) 696 return ext4_dio_write_iter(iocb, from); 697 else 698 return ext4_buffered_write_iter(iocb, from); 699 } 700 701 #ifdef CONFIG_FS_DAX 702 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf, unsigned int order) 703 { 704 int error = 0; 705 vm_fault_t result; 706 int retries = 0; 707 handle_t *handle = NULL; 708 struct inode *inode = file_inode(vmf->vma->vm_file); 709 struct super_block *sb = inode->i_sb; 710 711 /* 712 * We have to distinguish real writes from writes which will result in a 713 * COW page; COW writes should *not* poke the journal (the file will not 714 * be changed). Doing so would cause unintended failures when mounted 715 * read-only. 716 * 717 * We check for VM_SHARED rather than vmf->cow_page since the latter is 718 * unset for order != 0 (i.e. only in do_cow_fault); for 719 * other sizes, dax_iomap_fault will handle splitting / fallback so that 720 * we eventually come back with a COW page. 721 */ 722 bool write = (vmf->flags & FAULT_FLAG_WRITE) && 723 (vmf->vma->vm_flags & VM_SHARED); 724 struct address_space *mapping = vmf->vma->vm_file->f_mapping; 725 pfn_t pfn; 726 727 if (write) { 728 sb_start_pagefault(sb); 729 file_update_time(vmf->vma->vm_file); 730 filemap_invalidate_lock_shared(mapping); 731 retry: 732 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE, 733 EXT4_DATA_TRANS_BLOCKS(sb)); 734 if (IS_ERR(handle)) { 735 filemap_invalidate_unlock_shared(mapping); 736 sb_end_pagefault(sb); 737 return VM_FAULT_SIGBUS; 738 } 739 } else { 740 filemap_invalidate_lock_shared(mapping); 741 } 742 result = dax_iomap_fault(vmf, order, &pfn, &error, &ext4_iomap_ops); 743 if (write) { 744 ext4_journal_stop(handle); 745 746 if ((result & VM_FAULT_ERROR) && error == -ENOSPC && 747 ext4_should_retry_alloc(sb, &retries)) 748 goto retry; 749 /* Handling synchronous page fault? */ 750 if (result & VM_FAULT_NEEDDSYNC) 751 result = dax_finish_sync_fault(vmf, order, pfn); 752 filemap_invalidate_unlock_shared(mapping); 753 sb_end_pagefault(sb); 754 } else { 755 filemap_invalidate_unlock_shared(mapping); 756 } 757 758 return result; 759 } 760 761 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf) 762 { 763 return ext4_dax_huge_fault(vmf, 0); 764 } 765 766 static const struct vm_operations_struct ext4_dax_vm_ops = { 767 .fault = ext4_dax_fault, 768 .huge_fault = ext4_dax_huge_fault, 769 .page_mkwrite = ext4_dax_fault, 770 .pfn_mkwrite = ext4_dax_fault, 771 }; 772 #else 773 #define ext4_dax_vm_ops ext4_file_vm_ops 774 #endif 775 776 static const struct vm_operations_struct ext4_file_vm_ops = { 777 .fault = filemap_fault, 778 .map_pages = filemap_map_pages, 779 .page_mkwrite = ext4_page_mkwrite, 780 }; 781 782 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) 783 { 784 struct inode *inode = file->f_mapping->host; 785 struct dax_device *dax_dev = EXT4_SB(inode->i_sb)->s_daxdev; 786 787 if (unlikely(ext4_forced_shutdown(inode->i_sb))) 788 return -EIO; 789 790 /* 791 * We don't support synchronous mappings for non-DAX files and 792 * for DAX files if underneath dax_device is not synchronous. 793 */ 794 if (!daxdev_mapping_supported(vma, dax_dev)) 795 return -EOPNOTSUPP; 796 797 file_accessed(file); 798 if (IS_DAX(file_inode(file))) { 799 vma->vm_ops = &ext4_dax_vm_ops; 800 vm_flags_set(vma, VM_HUGEPAGE); 801 } else { 802 vma->vm_ops = &ext4_file_vm_ops; 803 } 804 return 0; 805 } 806 807 static int ext4_sample_last_mounted(struct super_block *sb, 808 struct vfsmount *mnt) 809 { 810 struct ext4_sb_info *sbi = EXT4_SB(sb); 811 struct path path; 812 char buf[64], *cp; 813 handle_t *handle; 814 int err; 815 816 if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED))) 817 return 0; 818 819 if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb)) 820 return 0; 821 822 ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED); 823 /* 824 * Sample where the filesystem has been mounted and 825 * store it in the superblock for sysadmin convenience 826 * when trying to sort through large numbers of block 827 * devices or filesystem images. 828 */ 829 memset(buf, 0, sizeof(buf)); 830 path.mnt = mnt; 831 path.dentry = mnt->mnt_root; 832 cp = d_path(&path, buf, sizeof(buf)); 833 err = 0; 834 if (IS_ERR(cp)) 835 goto out; 836 837 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1); 838 err = PTR_ERR(handle); 839 if (IS_ERR(handle)) 840 goto out; 841 BUFFER_TRACE(sbi->s_sbh, "get_write_access"); 842 err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh, 843 EXT4_JTR_NONE); 844 if (err) 845 goto out_journal; 846 lock_buffer(sbi->s_sbh); 847 strtomem_pad(sbi->s_es->s_last_mounted, cp, 0); 848 ext4_superblock_csum_set(sb); 849 unlock_buffer(sbi->s_sbh); 850 ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh); 851 out_journal: 852 ext4_journal_stop(handle); 853 out: 854 sb_end_intwrite(sb); 855 return err; 856 } 857 858 static int ext4_file_open(struct inode *inode, struct file *filp) 859 { 860 int ret; 861 862 if (unlikely(ext4_forced_shutdown(inode->i_sb))) 863 return -EIO; 864 865 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt); 866 if (ret) 867 return ret; 868 869 ret = fscrypt_file_open(inode, filp); 870 if (ret) 871 return ret; 872 873 ret = fsverity_file_open(inode, filp); 874 if (ret) 875 return ret; 876 877 /* 878 * Set up the jbd2_inode if we are opening the inode for 879 * writing and the journal is present 880 */ 881 if (filp->f_mode & FMODE_WRITE) { 882 ret = ext4_inode_attach_jinode(inode); 883 if (ret < 0) 884 return ret; 885 } 886 887 filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT; 888 return dquot_file_open(inode, filp); 889 } 890 891 /* 892 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values 893 * by calling generic_file_llseek_size() with the appropriate maxbytes 894 * value for each. 895 */ 896 loff_t ext4_llseek(struct file *file, loff_t offset, int whence) 897 { 898 struct inode *inode = file->f_mapping->host; 899 loff_t maxbytes; 900 901 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) 902 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes; 903 else 904 maxbytes = inode->i_sb->s_maxbytes; 905 906 switch (whence) { 907 default: 908 return generic_file_llseek_size(file, offset, whence, 909 maxbytes, i_size_read(inode)); 910 case SEEK_HOLE: 911 inode_lock_shared(inode); 912 offset = iomap_seek_hole(inode, offset, 913 &ext4_iomap_report_ops); 914 inode_unlock_shared(inode); 915 break; 916 case SEEK_DATA: 917 inode_lock_shared(inode); 918 offset = iomap_seek_data(inode, offset, 919 &ext4_iomap_report_ops); 920 inode_unlock_shared(inode); 921 break; 922 } 923 924 if (offset < 0) 925 return offset; 926 return vfs_setpos(file, offset, maxbytes); 927 } 928 929 const struct file_operations ext4_file_operations = { 930 .llseek = ext4_llseek, 931 .read_iter = ext4_file_read_iter, 932 .write_iter = ext4_file_write_iter, 933 .iopoll = iocb_bio_iopoll, 934 .unlocked_ioctl = ext4_ioctl, 935 #ifdef CONFIG_COMPAT 936 .compat_ioctl = ext4_compat_ioctl, 937 #endif 938 .mmap = ext4_file_mmap, 939 .open = ext4_file_open, 940 .release = ext4_release_file, 941 .fsync = ext4_sync_file, 942 .get_unmapped_area = thp_get_unmapped_area, 943 .splice_read = ext4_file_splice_read, 944 .splice_write = iter_file_splice_write, 945 .fallocate = ext4_fallocate, 946 .fop_flags = FOP_MMAP_SYNC | FOP_BUFFER_RASYNC | 947 FOP_DIO_PARALLEL_WRITE, 948 }; 949 950 const struct inode_operations ext4_file_inode_operations = { 951 .setattr = ext4_setattr, 952 .getattr = ext4_file_getattr, 953 .listxattr = ext4_listxattr, 954 .get_inode_acl = ext4_get_acl, 955 .set_acl = ext4_set_acl, 956 .fiemap = ext4_fiemap, 957 .fileattr_get = ext4_fileattr_get, 958 .fileattr_set = ext4_fileattr_set, 959 }; 960 961