개념 설명 전체 · v6.18.37 / fs/ext4/file.c
1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext4/file.c 4 * 5 * Copyright (C) 1992, 1993, 1994, 1995 6 * Remy Card ([email protected]) 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 * ([email protected]) 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 (ext4_inode_orphan_tracked(inode) && 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); 379 380 381 if (!error && size && (flags & IOMAP_DIO_UNWRITTEN) && 382 (iocb->ki_flags & IOCB_ATOMIC)) 383 error = ext4_convert_unwritten_extents_atomic(NULL, inode, pos, 384 size); 385 else if (!error && size && flags & IOMAP_DIO_UNWRITTEN) 386 error = ext4_convert_unwritten_extents(NULL, inode, pos, size); 387 if (error) 388 return error; 389 /* 390 * Note that EXT4_I(inode)->i_disksize can get extended up to 391 * inode->i_size while the I/O was running due to writeback of delalloc 392 * blocks. But the code in ext4_iomap_alloc() is careful to use 393 * zeroed/unwritten extents if this is possible; thus we won't leave 394 * uninitialized blocks in a file even if we didn't succeed in writing 395 * as much as we intended. Also we can race with truncate or write 396 * expanding the file so we have to be a bit careful here. 397 */ 398 if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize) && 399 pos + size <= i_size_read(inode)) 400 return 0; 401 error = ext4_handle_inode_extension(inode, pos, size, size); 402 return error < 0 ? error : 0; 403 } 404 405 static const struct iomap_dio_ops ext4_dio_write_ops = { 406 .end_io = ext4_dio_write_end_io, 407 }; 408 409 /* 410 * The intention here is to start with shared lock acquired then see if any 411 * condition requires an exclusive inode lock. If yes, then we restart the 412 * whole operation by releasing the shared lock and acquiring exclusive lock. 413 * 414 * - For unaligned_io we never take shared lock as it may cause data corruption 415 * when two unaligned IO tries to modify the same block e.g. while zeroing. 416 * 417 * - For extending writes case we don't take the shared lock, since it requires 418 * updating inode i_disksize and/or orphan handling with exclusive lock. 419 * 420 * - shared locking will only be true mostly with overwrites, including 421 * initialized blocks and unwritten blocks. For overwrite unwritten blocks 422 * we protect splitting extents by i_data_sem in ext4_inode_info, so we can 423 * also release exclusive i_rwsem lock. 424 * 425 * - Otherwise we will switch to exclusive i_rwsem lock. 426 */ 427 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from, 428 bool *ilock_shared, bool *extend, 429 bool *unwritten, int *dio_flags) 430 { 431 struct file *file = iocb->ki_filp; 432 struct inode *inode = file_inode(file); 433 loff_t offset; 434 size_t count; 435 ssize_t ret; 436 bool overwrite, unaligned_io; 437 438 restart: 439 ret = ext4_generic_write_checks(iocb, from); 440 if (ret <= 0) 441 goto out; 442 443 offset = iocb->ki_pos; 444 count = ret; 445 446 unaligned_io = ext4_unaligned_io(inode, from, offset); 447 *extend = ext4_extending_io(inode, offset, count); 448 overwrite = ext4_overwrite_io(inode, offset, count, unwritten); 449 450 /* 451 * Determine whether we need to upgrade to an exclusive lock. This is 452 * required to change security info in file_modified(), for extending 453 * I/O, any form of non-overwrite I/O, and unaligned I/O to unwritten 454 * extents (as partial block zeroing may be required). 455 * 456 * Note that unaligned writes are allowed under shared lock so long as 457 * they are pure overwrites. Otherwise, concurrent unaligned writes risk 458 * data corruption due to partial block zeroing in the dio layer, and so 459 * the I/O must occur exclusively. 460 */ 461 if (*ilock_shared && 462 ((!IS_NOSEC(inode) || *extend || !overwrite || 463 (unaligned_io && *unwritten)))) { 464 if (iocb->ki_flags & IOCB_NOWAIT) { 465 ret = -EAGAIN; 466 goto out; 467 } 468 inode_unlock_shared(inode); 469 *ilock_shared = false; 470 inode_lock(inode); 471 goto restart; 472 } 473 474 /* 475 * Now that locking is settled, determine dio flags and exclusivity 476 * requirements. We don't use DIO_OVERWRITE_ONLY because we enforce 477 * behavior already. The inode lock is already held exclusive if the 478 * write is non-overwrite or extending, so drain all outstanding dio and 479 * set the force wait dio flag. 480 */ 481 if (!*ilock_shared && (unaligned_io || *extend)) { 482 if (iocb->ki_flags & IOCB_NOWAIT) { 483 ret = -EAGAIN; 484 goto out; 485 } 486 if (unaligned_io && (!overwrite || *unwritten)) 487 inode_dio_wait(inode); 488 *dio_flags = IOMAP_DIO_FORCE_WAIT; 489 } 490 491 ret = file_modified(file); 492 if (ret < 0) 493 goto out; 494 495 return count; 496 out: 497 if (*ilock_shared) 498 inode_unlock_shared(inode); 499 else 500 inode_unlock(inode); 501 return ret; 502 } 503 504 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) 505 { 506 ssize_t ret; 507 handle_t *handle; 508 struct inode *inode = file_inode(iocb->ki_filp); 509 loff_t offset = iocb->ki_pos; 510 size_t count = iov_iter_count(from); 511 const struct iomap_ops *iomap_ops = &ext4_iomap_ops; 512 bool extend = false, unwritten = false; 513 bool ilock_shared = true; 514 int dio_flags = 0; 515 516 /* 517 * Quick check here without any i_rwsem lock to see if it is extending 518 * IO. A more reliable check is done in ext4_dio_write_checks() with 519 * proper locking in place. 520 */ 521 if (offset + count > i_size_read(inode)) 522 ilock_shared = false; 523 524 if (iocb->ki_flags & IOCB_NOWAIT) { 525 if (ilock_shared) { 526 if (!inode_trylock_shared(inode)) 527 return -EAGAIN; 528 } else { 529 if (!inode_trylock(inode)) 530 return -EAGAIN; 531 } 532 } else { 533 if (ilock_shared) 534 inode_lock_shared(inode); 535 else 536 inode_lock(inode); 537 } 538 539 /* Fallback to buffered I/O if the inode does not support direct I/O. */ 540 if (!ext4_should_use_dio(iocb, from)) { 541 if (ilock_shared) 542 inode_unlock_shared(inode); 543 else 544 inode_unlock(inode); 545 return ext4_buffered_write_iter(iocb, from); 546 } 547 548 /* 549 * Prevent inline data from being created since we are going to allocate 550 * blocks for DIO. We know the inode does not currently have inline data 551 * because ext4_should_use_dio() checked for it, but we have to clear 552 * the state flag before the write checks because a lock cycle could 553 * introduce races with other writers. 554 */ 555 ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA); 556 557 ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend, 558 &unwritten, &dio_flags); 559 if (ret <= 0) 560 return ret; 561 562 offset = iocb->ki_pos; 563 count = ret; 564 565 if (extend) { 566 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); 567 if (IS_ERR(handle)) { 568 ret = PTR_ERR(handle); 569 goto out; 570 } 571 572 ret = ext4_orphan_add(handle, inode); 573 ext4_journal_stop(handle); 574 if (ret) 575 goto out; 576 } 577 578 if (ilock_shared && !unwritten) 579 iomap_ops = &ext4_iomap_overwrite_ops; 580 ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops, 581 dio_flags, NULL, 0); 582 if (ret == -ENOTBLK) 583 ret = 0; 584 if (extend) { 585 /* 586 * We always perform extending DIO write synchronously so by 587 * now the IO is completed and ext4_handle_inode_extension() 588 * was called. Cleanup the inode in case of error or race with 589 * writeback of delalloc blocks. 590 */ 591 WARN_ON_ONCE(ret == -EIOCBQUEUED); 592 ext4_inode_extension_cleanup(inode, ret < 0); 593 } 594 595 out: 596 if (ilock_shared) 597 inode_unlock_shared(inode); 598 else 599 inode_unlock(inode); 600 601 if (ret >= 0 && iov_iter_count(from)) { 602 ssize_t err; 603 loff_t endbyte; 604 605 /* 606 * There is no support for atomic writes on buffered-io yet, 607 * we should never fallback to buffered-io for DIO atomic 608 * writes. 609 */ 610 WARN_ON_ONCE(iocb->ki_flags & IOCB_ATOMIC); 611 612 offset = iocb->ki_pos; 613 err = ext4_buffered_write_iter(iocb, from); 614 if (err < 0) 615 return err; 616 617 /* 618 * We need to ensure that the pages within the page cache for 619 * the range covered by this I/O are written to disk and 620 * invalidated. This is in attempt to preserve the expected 621 * direct I/O semantics in the case we fallback to buffered I/O 622 * to complete off the I/O request. 623 */ 624 ret += err; 625 endbyte = offset + err - 1; 626 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping, 627 offset, endbyte); 628 if (!err) 629 invalidate_mapping_pages(iocb->ki_filp->f_mapping, 630 offset >> PAGE_SHIFT, 631 endbyte >> PAGE_SHIFT); 632 } 633 634 return ret; 635 } 636 637 #ifdef CONFIG_FS_DAX 638 static ssize_t 639 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) 640 { 641 ssize_t ret; 642 size_t count; 643 loff_t offset; 644 handle_t *handle; 645 bool extend = false; 646 struct inode *inode = file_inode(iocb->ki_filp); 647 648 if (iocb->ki_flags & IOCB_NOWAIT) { 649 if (!inode_trylock(inode)) 650 return -EAGAIN; 651 } else { 652 inode_lock(inode); 653 } 654 655 ret = ext4_write_checks(iocb, from); 656 if (ret <= 0) 657 goto out; 658 659 offset = iocb->ki_pos; 660 count = iov_iter_count(from); 661 662 if (offset + count > EXT4_I(inode)->i_disksize) { 663 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); 664 if (IS_ERR(handle)) { 665 ret = PTR_ERR(handle); 666 goto out; 667 } 668 669 ret = ext4_orphan_add(handle, inode); 670 if (ret) { 671 ext4_journal_stop(handle); 672 goto out; 673 } 674 675 extend = true; 676 ext4_journal_stop(handle); 677 } 678 679 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops); 680 681 if (extend) { 682 ret = ext4_handle_inode_extension(inode, offset, ret, count); 683 ext4_inode_extension_cleanup(inode, ret < (ssize_t)count); 684 } 685 out: 686 inode_unlock(inode); 687 if (ret > 0) 688 ret = generic_write_sync(iocb, ret); 689 return ret; 690 } 691 #endif 692 693 static ssize_t 694 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 695 { 696 int ret; 697 struct inode *inode = file_inode(iocb->ki_filp); 698 699 ret = ext4_emergency_state(inode->i_sb); 700 if (unlikely(ret)) 701 return ret; 702 703 #ifdef CONFIG_FS_DAX 704 if (IS_DAX(inode)) 705 return ext4_dax_write_iter(iocb, from); 706 #endif 707 708 if (iocb->ki_flags & IOCB_ATOMIC) { 709 size_t len = iov_iter_count(from); 710 711 if (len < EXT4_SB(inode->i_sb)->s_awu_min || 712 len > EXT4_SB(inode->i_sb)->s_awu_max) 713 return -EINVAL; 714 715 ret = generic_atomic_write_valid(iocb, from); 716 if (ret) 717 return ret; 718 } 719 720 if (iocb->ki_flags & IOCB_DIRECT) 721 return ext4_dio_write_iter(iocb, from); 722 else 723 return ext4_buffered_write_iter(iocb, from); 724 } 725 726 #ifdef CONFIG_FS_DAX 727 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf, unsigned int order) 728 { 729 int error = 0; 730 vm_fault_t result; 731 int retries = 0; 732 handle_t *handle = NULL; 733 struct inode *inode = file_inode(vmf->vma->vm_file); 734 struct super_block *sb = inode->i_sb; 735 736 /* 737 * We have to distinguish real writes from writes which will result in a 738 * COW page; COW writes should *not* poke the journal (the file will not 739 * be changed). Doing so would cause unintended failures when mounted 740 * read-only. 741 * 742 * We check for VM_SHARED rather than vmf->cow_page since the latter is 743 * unset for order != 0 (i.e. only in do_cow_fault); for 744 * other sizes, dax_iomap_fault will handle splitting / fallback so that 745 * we eventually come back with a COW page. 746 */ 747 bool write = (vmf->flags & FAULT_FLAG_WRITE) && 748 (vmf->vma->vm_flags & VM_SHARED); 749 struct address_space *mapping = vmf->vma->vm_file->f_mapping; 750 unsigned long pfn; 751 752 if (write) { 753 sb_start_pagefault(sb); 754 file_update_time(vmf->vma->vm_file); 755 filemap_invalidate_lock_shared(mapping); 756 retry: 757 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE, 758 EXT4_DATA_TRANS_BLOCKS(sb)); 759 if (IS_ERR(handle)) { 760 filemap_invalidate_unlock_shared(mapping); 761 sb_end_pagefault(sb); 762 return VM_FAULT_SIGBUS; 763 } 764 } else { 765 filemap_invalidate_lock_shared(mapping); 766 } 767 result = dax_iomap_fault(vmf, order, &pfn, &error, &ext4_iomap_ops); 768 if (write) { 769 ext4_journal_stop(handle); 770 771 if ((result & VM_FAULT_ERROR) && error == -ENOSPC && 772 ext4_should_retry_alloc(sb, &retries)) 773 goto retry; 774 /* Handling synchronous page fault? */ 775 if (result & VM_FAULT_NEEDDSYNC) 776 result = dax_finish_sync_fault(vmf, order, pfn); 777 filemap_invalidate_unlock_shared(mapping); 778 sb_end_pagefault(sb); 779 } else { 780 filemap_invalidate_unlock_shared(mapping); 781 } 782 783 return result; 784 } 785 786 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf) 787 { 788 return ext4_dax_huge_fault(vmf, 0); 789 } 790 791 static const struct vm_operations_struct ext4_dax_vm_ops = { 792 .fault = ext4_dax_fault, 793 .huge_fault = ext4_dax_huge_fault, 794 .page_mkwrite = ext4_dax_fault, 795 .pfn_mkwrite = ext4_dax_fault, 796 }; 797 #else 798 #define ext4_dax_vm_ops ext4_file_vm_ops 799 #endif 800 801 static const struct vm_operations_struct ext4_file_vm_ops = { 802 .fault = filemap_fault, 803 .map_pages = filemap_map_pages, 804 .page_mkwrite = ext4_page_mkwrite, 805 }; 806 807 static int ext4_file_mmap_prepare(struct vm_area_desc *desc) 808 { 809 int ret; 810 struct file *file = desc->file; 811 struct inode *inode = file->f_mapping->host; 812 struct dax_device *dax_dev = EXT4_SB(inode->i_sb)->s_daxdev; 813 814 if (file->f_mode & FMODE_WRITE) 815 ret = ext4_emergency_state(inode->i_sb); 816 else 817 ret = ext4_forced_shutdown(inode->i_sb) ? -EIO : 0; 818 if (unlikely(ret)) 819 return ret; 820 821 /* 822 * We don't support synchronous mappings for non-DAX files and 823 * for DAX files if underneath dax_device is not synchronous. 824 */ 825 if (!daxdev_mapping_supported(desc->vm_flags, file_inode(file), dax_dev)) 826 return -EOPNOTSUPP; 827 828 file_accessed(file); 829 if (IS_DAX(file_inode(file))) { 830 desc->vm_ops = &ext4_dax_vm_ops; 831 desc->vm_flags |= VM_HUGEPAGE; 832 } else { 833 desc->vm_ops = &ext4_file_vm_ops; 834 } 835 return 0; 836 } 837 838 static int ext4_sample_last_mounted(struct super_block *sb, 839 struct vfsmount *mnt) 840 { 841 struct ext4_sb_info *sbi = EXT4_SB(sb); 842 struct path path; 843 char buf[64], *cp; 844 handle_t *handle; 845 int err; 846 847 if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED))) 848 return 0; 849 850 if (ext4_emergency_state(sb) || sb_rdonly(sb) || 851 !sb_start_intwrite_trylock(sb)) 852 return 0; 853 854 ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED); 855 /* 856 * Sample where the filesystem has been mounted and 857 * store it in the superblock for sysadmin convenience 858 * when trying to sort through large numbers of block 859 * devices or filesystem images. 860 */ 861 memset(buf, 0, sizeof(buf)); 862 path.mnt = mnt; 863 path.dentry = mnt->mnt_root; 864 cp = d_path(&path, buf, sizeof(buf)); 865 err = 0; 866 if (IS_ERR(cp)) 867 goto out; 868 869 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1); 870 err = PTR_ERR(handle); 871 if (IS_ERR(handle)) 872 goto out; 873 BUFFER_TRACE(sbi->s_sbh, "get_write_access"); 874 err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh, 875 EXT4_JTR_NONE); 876 if (err) 877 goto out_journal; 878 lock_buffer(sbi->s_sbh); 879 strtomem_pad(sbi->s_es->s_last_mounted, cp, 0); 880 ext4_superblock_csum_set(sb); 881 unlock_buffer(sbi->s_sbh); 882 ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh); 883 out_journal: 884 ext4_journal_stop(handle); 885 out: 886 sb_end_intwrite(sb); 887 return err; 888 } 889 890 static int ext4_file_open(struct inode *inode, struct file *filp) 891 { 892 int ret; 893 894 if (filp->f_mode & FMODE_WRITE) 895 ret = ext4_emergency_state(inode->i_sb); 896 else 897 ret = ext4_forced_shutdown(inode->i_sb) ? -EIO : 0; 898 if (unlikely(ret)) 899 return ret; 900 901 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt); 902 if (ret) 903 return ret; 904 905 ret = fscrypt_file_open(inode, filp); 906 if (ret) 907 return ret; 908 909 ret = fsverity_file_open(inode, filp); 910 if (ret) 911 return ret; 912 913 /* 914 * Set up the jbd2_inode if we are opening the inode for 915 * writing and the journal is present 916 */ 917 if (filp->f_mode & FMODE_WRITE) { 918 ret = ext4_inode_attach_jinode(inode); 919 if (ret < 0) 920 return ret; 921 } 922 923 if (ext4_inode_can_atomic_write(inode)) 924 filp->f_mode |= FMODE_CAN_ATOMIC_WRITE; 925 926 filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT; 927 return dquot_file_open(inode, filp); 928 } 929 930 /* 931 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values 932 * by calling generic_file_llseek_size() with the appropriate maxbytes 933 * value for each. 934 */ 935 loff_t ext4_llseek(struct file *file, loff_t offset, int whence) 936 { 937 struct inode *inode = file->f_mapping->host; 938 loff_t maxbytes = ext4_get_maxbytes(inode); 939 940 switch (whence) { 941 default: 942 return generic_file_llseek_size(file, offset, whence, 943 maxbytes, i_size_read(inode)); 944 case SEEK_HOLE: 945 inode_lock_shared(inode); 946 offset = iomap_seek_hole(inode, offset, 947 &ext4_iomap_report_ops); 948 inode_unlock_shared(inode); 949 break; 950 case SEEK_DATA: 951 inode_lock_shared(inode); 952 offset = iomap_seek_data(inode, offset, 953 &ext4_iomap_report_ops); 954 inode_unlock_shared(inode); 955 break; 956 } 957 958 if (offset < 0) 959 return offset; 960 return vfs_setpos(file, offset, maxbytes); 961 } 962 963 const struct file_operations ext4_file_operations = { 964 .llseek = ext4_llseek, 965 .read_iter = ext4_file_read_iter, 966 .write_iter = ext4_file_write_iter, 967 .iopoll = iocb_bio_iopoll, 968 .unlocked_ioctl = ext4_ioctl, 969 #ifdef CONFIG_COMPAT 970 .compat_ioctl = ext4_compat_ioctl, 971 #endif 972 .mmap_prepare = ext4_file_mmap_prepare, 973 .open = ext4_file_open, 974 .release = ext4_release_file, 975 .fsync = ext4_sync_file, 976 .get_unmapped_area = thp_get_unmapped_area, 977 .splice_read = ext4_file_splice_read, 978 .splice_write = iter_file_splice_write, 979 .fallocate = ext4_fallocate, 980 .fop_flags = FOP_MMAP_SYNC | FOP_BUFFER_RASYNC | 981 FOP_DIO_PARALLEL_WRITE | 982 FOP_DONTCACHE, 983 }; 984 985 const struct inode_operations ext4_file_inode_operations = { 986 .setattr = ext4_setattr, 987 .getattr = ext4_file_getattr, 988 .listxattr = ext4_listxattr, 989 .get_inode_acl = ext4_get_acl, 990 .set_acl = ext4_set_acl, 991 .fiemap = ext4_fiemap, 992 .fileattr_get = ext4_fileattr_get, 993 .fileattr_set = ext4_fileattr_set, 994 }; 995