1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2010 Red Hat, Inc. 4 * Copyright (c) 2016-2025 Christoph Hellwig. 5 */ 6 #include <linux/module.h> 7 #include <linux/compiler.h> 8 #include <linux/fs.h> 9 #include <linux/fscrypt.h> 10 #include <linux/pagemap.h> 11 #include <linux/iomap.h> 12 #include <linux/backing-dev.h> 13 #include <linux/uio.h> 14 #include <linux/task_io_accounting_ops.h> 15 #include "internal.h" 16 #include "trace.h" 17 18 #include "../internal.h" 19 20 /* 21 * Private flags for iomap_dio, must not overlap with the public ones in 22 * iomap.h: 23 */ 24 #define IOMAP_DIO_NO_INVALIDATE (1U << 25) 25 #define IOMAP_DIO_CALLER_COMP (1U << 26) 26 #define IOMAP_DIO_INLINE_COMP (1U << 27) 27 #define IOMAP_DIO_WRITE_THROUGH (1U << 28) 28 #define IOMAP_DIO_NEED_SYNC (1U << 29) 29 #define IOMAP_DIO_WRITE (1U << 30) 30 #define IOMAP_DIO_DIRTY (1U << 31) 31 32 /* 33 * Used for sub block zeroing in iomap_dio_zero() 34 */ 35 #define IOMAP_ZERO_PAGE_SIZE (SZ_64K) 36 #define IOMAP_ZERO_PAGE_ORDER (get_order(IOMAP_ZERO_PAGE_SIZE)) 37 static struct page *zero_page; 38 39 struct iomap_dio { 40 struct kiocb *iocb; 41 const struct iomap_dio_ops *dops; 42 loff_t i_size; 43 loff_t size; 44 atomic_t ref; 45 unsigned flags; 46 int error; 47 size_t done_before; 48 bool wait_for_completion; 49 50 union { 51 /* used during submission and for synchronous completion: */ 52 struct { 53 struct iov_iter *iter; 54 struct task_struct *waiter; 55 } submit; 56 57 /* used for aio completion: */ 58 struct { 59 struct work_struct work; 60 } aio; 61 }; 62 }; 63 64 static struct bio *iomap_dio_alloc_bio(const struct iomap_iter *iter, 65 struct iomap_dio *dio, unsigned short nr_vecs, blk_opf_t opf) 66 { 67 if (dio->dops && dio->dops->bio_set) 68 return bio_alloc_bioset(iter->iomap.bdev, nr_vecs, opf, 69 GFP_KERNEL, dio->dops->bio_set); 70 return bio_alloc(iter->iomap.bdev, nr_vecs, opf, GFP_KERNEL); 71 } 72 73 static void iomap_dio_submit_bio(const struct iomap_iter *iter, 74 struct iomap_dio *dio, struct bio *bio, loff_t pos) 75 { 76 struct kiocb *iocb = dio->iocb; 77 78 atomic_inc(&dio->ref); 79 80 /* Sync dio can't be polled reliably */ 81 if ((iocb->ki_flags & IOCB_HIPRI) && !is_sync_kiocb(iocb)) { 82 bio_set_polled(bio, iocb); 83 WRITE_ONCE(iocb->private, bio); 84 } 85 86 if (dio->dops && dio->dops->submit_io) { 87 dio->dops->submit_io(iter, bio, pos); 88 } else { 89 WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_ANON_WRITE); 90 submit_bio(bio); 91 } 92 } 93 94 ssize_t iomap_dio_complete(struct iomap_dio *dio) 95 { 96 const struct iomap_dio_ops *dops = dio->dops; 97 struct kiocb *iocb = dio->iocb; 98 loff_t offset = iocb->ki_pos; 99 ssize_t ret = dio->error; 100 101 if (dops && dops->end_io) 102 ret = dops->end_io(iocb, dio->size, ret, dio->flags); 103 104 if (likely(!ret)) { 105 ret = dio->size; 106 /* check for short read */ 107 if (offset + ret > dio->i_size && 108 !(dio->flags & IOMAP_DIO_WRITE)) 109 ret = dio->i_size - offset; 110 } 111 112 /* 113 * Try again to invalidate clean pages which might have been cached by 114 * non-direct readahead, or faulted in by get_user_pages() if the source 115 * of the write was an mmap'ed region of the file we're writing. Either 116 * one is a pretty crazy thing to do, so we don't support it 100%. If 117 * this invalidation fails, tough, the write still worked... 118 * 119 * And this page cache invalidation has to be after ->end_io(), as some 120 * filesystems convert unwritten extents to real allocations in 121 * ->end_io() when necessary, otherwise a racing buffer read would cache 122 * zeros from unwritten extents. 123 */ 124 if (!dio->error && dio->size && (dio->flags & IOMAP_DIO_WRITE) && 125 !(dio->flags & IOMAP_DIO_NO_INVALIDATE)) 126 kiocb_invalidate_post_direct_write(iocb, dio->size); 127 128 inode_dio_end(file_inode(iocb->ki_filp)); 129 130 if (ret > 0) { 131 iocb->ki_pos += ret; 132 133 /* 134 * If this is a DSYNC write, make sure we push it to stable 135 * storage now that we've written data. 136 */ 137 if (dio->flags & IOMAP_DIO_NEED_SYNC) 138 ret = generic_write_sync(iocb, ret); 139 if (ret > 0) 140 ret += dio->done_before; 141 } 142 trace_iomap_dio_complete(iocb, dio->error, ret); 143 kfree(dio); 144 return ret; 145 } 146 EXPORT_SYMBOL_GPL(iomap_dio_complete); 147 148 static ssize_t iomap_dio_deferred_complete(void *data) 149 { 150 return iomap_dio_complete(data); 151 } 152 153 static void iomap_dio_complete_work(struct work_struct *work) 154 { 155 struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work); 156 struct kiocb *iocb = dio->iocb; 157 158 iocb->ki_complete(iocb, iomap_dio_complete(dio)); 159 } 160 161 /* 162 * Set an error in the dio if none is set yet. We have to use cmpxchg 163 * as the submission context and the completion context(s) can race to 164 * update the error. 165 */ 166 static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret) 167 { 168 cmpxchg(&dio->error, 0, ret); 169 } 170 171 /* 172 * Called when dio->ref reaches zero from an I/O completion. 173 */ 174 static void iomap_dio_done(struct iomap_dio *dio) 175 { 176 struct kiocb *iocb = dio->iocb; 177 178 if (dio->wait_for_completion) { 179 /* 180 * Synchronous I/O, task itself will handle any completion work 181 * that needs after IO. All we need to do is wake the task. 182 */ 183 struct task_struct *waiter = dio->submit.waiter; 184 185 WRITE_ONCE(dio->submit.waiter, NULL); 186 blk_wake_io_task(waiter); 187 } else if (dio->flags & IOMAP_DIO_INLINE_COMP) { 188 WRITE_ONCE(iocb->private, NULL); 189 iomap_dio_complete_work(&dio->aio.work); 190 } else if (dio->flags & IOMAP_DIO_CALLER_COMP) { 191 /* 192 * If this dio is flagged with IOMAP_DIO_CALLER_COMP, then 193 * schedule our completion that way to avoid an async punt to a 194 * workqueue. 195 */ 196 /* only polled IO cares about private cleared */ 197 iocb->private = dio; 198 iocb->dio_complete = iomap_dio_deferred_complete; 199 200 /* 201 * Invoke ->ki_complete() directly. We've assigned our 202 * dio_complete callback handler, and since the issuer set 203 * IOCB_DIO_CALLER_COMP, we know their ki_complete handler will 204 * notice ->dio_complete being set and will defer calling that 205 * handler until it can be done from a safe task context. 206 * 207 * Note that the 'res' being passed in here is not important 208 * for this case. The actual completion value of the request 209 * will be gotten from dio_complete when that is run by the 210 * issuer. 211 */ 212 iocb->ki_complete(iocb, 0); 213 } else { 214 struct inode *inode = file_inode(iocb->ki_filp); 215 216 /* 217 * Async DIO completion that requires filesystem level 218 * completion work gets punted to a work queue to complete as 219 * the operation may require more IO to be issued to finalise 220 * filesystem metadata changes or guarantee data integrity. 221 */ 222 INIT_WORK(&dio->aio.work, iomap_dio_complete_work); 223 queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work); 224 } 225 } 226 227 void iomap_dio_bio_end_io(struct bio *bio) 228 { 229 struct iomap_dio *dio = bio->bi_private; 230 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY); 231 232 if (bio->bi_status) 233 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status)); 234 235 if (atomic_dec_and_test(&dio->ref)) 236 iomap_dio_done(dio); 237 238 if (should_dirty) { 239 bio_check_pages_dirty(bio); 240 } else { 241 bio_release_pages(bio, false); 242 bio_put(bio); 243 } 244 } 245 EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io); 246 247 u32 iomap_finish_ioend_direct(struct iomap_ioend *ioend) 248 { 249 struct iomap_dio *dio = ioend->io_bio.bi_private; 250 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY); 251 u32 vec_count = ioend->io_bio.bi_vcnt; 252 253 if (ioend->io_error) 254 iomap_dio_set_error(dio, ioend->io_error); 255 256 if (atomic_dec_and_test(&dio->ref)) { 257 /* 258 * Try to avoid another context switch for the completion given 259 * that we are already called from the ioend completion 260 * workqueue, but never invalidate pages from this thread to 261 * avoid deadlocks with buffered I/O completions. Tough luck if 262 * you hit the tiny race with someone dirtying the range now 263 * between this check and the actual completion. 264 */ 265 if (!dio->iocb->ki_filp->f_mapping->nrpages) { 266 dio->flags |= IOMAP_DIO_INLINE_COMP; 267 dio->flags |= IOMAP_DIO_NO_INVALIDATE; 268 } 269 dio->flags &= ~IOMAP_DIO_CALLER_COMP; 270 iomap_dio_done(dio); 271 } 272 273 if (should_dirty) { 274 bio_check_pages_dirty(&ioend->io_bio); 275 } else { 276 bio_release_pages(&ioend->io_bio, false); 277 bio_put(&ioend->io_bio); 278 } 279 280 /* 281 * Return the number of bvecs completed as even direct I/O completions 282 * do significant per-folio work and we'll still want to give up the 283 * CPU after a lot of completions. 284 */ 285 return vec_count; 286 } 287 288 static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, 289 loff_t pos, unsigned len) 290 { 291 struct inode *inode = file_inode(dio->iocb->ki_filp); 292 struct bio *bio; 293 294 if (!len) 295 return 0; 296 /* 297 * Max block size supported is 64k 298 */ 299 if (WARN_ON_ONCE(len > IOMAP_ZERO_PAGE_SIZE)) 300 return -EINVAL; 301 302 bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE); 303 fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, 304 GFP_KERNEL); 305 bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos); 306 bio->bi_private = dio; 307 bio->bi_end_io = iomap_dio_bio_end_io; 308 309 __bio_add_page(bio, zero_page, len, 0); 310 iomap_dio_submit_bio(iter, dio, bio, pos); 311 return 0; 312 } 313 314 /* 315 * Use a FUA write if we need datasync semantics and this is a pure data I/O 316 * that doesn't require any metadata updates (including after I/O completion 317 * such as unwritten extent conversion) and the underlying device either 318 * doesn't have a volatile write cache or supports FUA. 319 * This allows us to avoid cache flushes on I/O completion. 320 */ 321 static inline bool iomap_dio_can_use_fua(const struct iomap *iomap, 322 struct iomap_dio *dio) 323 { 324 if (iomap->flags & (IOMAP_F_SHARED | IOMAP_F_DIRTY)) 325 return false; 326 if (!(dio->flags & IOMAP_DIO_WRITE_THROUGH)) 327 return false; 328 return !bdev_write_cache(iomap->bdev) || bdev_fua(iomap->bdev); 329 } 330 331 static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) 332 { 333 const struct iomap *iomap = &iter->iomap; 334 struct inode *inode = iter->inode; 335 unsigned int fs_block_size = i_blocksize(inode), pad; 336 const loff_t length = iomap_length(iter); 337 loff_t pos = iter->pos; 338 blk_opf_t bio_opf = REQ_SYNC | REQ_IDLE; 339 struct bio *bio; 340 bool need_zeroout = false; 341 int nr_pages, ret = 0; 342 u64 copied = 0; 343 size_t orig_count; 344 345 if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) || 346 !bdev_iter_is_aligned(iomap->bdev, dio->submit.iter)) 347 return -EINVAL; 348 349 if (dio->flags & IOMAP_DIO_WRITE) { 350 bio_opf |= REQ_OP_WRITE; 351 352 if (iomap->flags & IOMAP_F_ATOMIC_BIO) { 353 /* 354 * Ensure that the mapping covers the full write 355 * length, otherwise it won't be submitted as a single 356 * bio, which is required to use hardware atomics. 357 */ 358 if (length != iter->len) 359 return -EINVAL; 360 bio_opf |= REQ_ATOMIC; 361 } 362 363 if (iomap->type == IOMAP_UNWRITTEN) { 364 dio->flags |= IOMAP_DIO_UNWRITTEN; 365 need_zeroout = true; 366 } 367 368 if (iomap->flags & IOMAP_F_SHARED) 369 dio->flags |= IOMAP_DIO_COW; 370 371 if (iomap->flags & IOMAP_F_NEW) { 372 need_zeroout = true; 373 } else if (iomap->type == IOMAP_MAPPED) { 374 if (iomap_dio_can_use_fua(iomap, dio)) 375 bio_opf |= REQ_FUA; 376 else 377 dio->flags &= ~IOMAP_DIO_WRITE_THROUGH; 378 } 379 380 /* 381 * We can only do deferred completion for pure overwrites that 382 * don't require additional I/O at completion time. 383 * 384 * This rules out writes that need zeroing or extent conversion, 385 * extend the file size, or issue metadata I/O or cache flushes 386 * during completion processing. 387 */ 388 if (need_zeroout || (pos >= i_size_read(inode)) || 389 ((dio->flags & IOMAP_DIO_NEED_SYNC) && 390 !(bio_opf & REQ_FUA))) 391 dio->flags &= ~IOMAP_DIO_CALLER_COMP; 392 } else { 393 bio_opf |= REQ_OP_READ; 394 } 395 396 /* 397 * Save the original count and trim the iter to just the extent we 398 * are operating on right now. The iter will be re-expanded once 399 * we are done. 400 */ 401 orig_count = iov_iter_count(dio->submit.iter); 402 iov_iter_truncate(dio->submit.iter, length); 403 404 if (!iov_iter_count(dio->submit.iter)) 405 goto out; 406 407 /* 408 * The rules for polled IO completions follow the guidelines as the 409 * ones we set for inline and deferred completions. If none of those 410 * are available for this IO, clear the polled flag. 411 */ 412 if (!(dio->flags & (IOMAP_DIO_INLINE_COMP|IOMAP_DIO_CALLER_COMP))) 413 dio->iocb->ki_flags &= ~IOCB_HIPRI; 414 415 if (need_zeroout) { 416 /* zero out from the start of the block to the write offset */ 417 pad = pos & (fs_block_size - 1); 418 419 ret = iomap_dio_zero(iter, dio, pos - pad, pad); 420 if (ret) 421 goto out; 422 } 423 424 nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS); 425 do { 426 size_t n; 427 if (dio->error) { 428 iov_iter_revert(dio->submit.iter, copied); 429 copied = ret = 0; 430 goto out; 431 } 432 433 bio = iomap_dio_alloc_bio(iter, dio, nr_pages, bio_opf); 434 fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, 435 GFP_KERNEL); 436 bio->bi_iter.bi_sector = iomap_sector(iomap, pos); 437 bio->bi_write_hint = inode->i_write_hint; 438 bio->bi_ioprio = dio->iocb->ki_ioprio; 439 bio->bi_private = dio; 440 bio->bi_end_io = iomap_dio_bio_end_io; 441 442 ret = bio_iov_iter_get_pages(bio, dio->submit.iter); 443 if (unlikely(ret)) { 444 /* 445 * We have to stop part way through an IO. We must fall 446 * through to the sub-block tail zeroing here, otherwise 447 * this short IO may expose stale data in the tail of 448 * the block we haven't written data to. 449 */ 450 bio_put(bio); 451 goto zero_tail; 452 } 453 454 n = bio->bi_iter.bi_size; 455 if (WARN_ON_ONCE((bio_opf & REQ_ATOMIC) && n != length)) { 456 /* 457 * An atomic write bio must cover the complete length, 458 * which it doesn't, so error. We may need to zero out 459 * the tail (complete FS block), similar to when 460 * bio_iov_iter_get_pages() returns an error, above. 461 */ 462 ret = -EINVAL; 463 bio_put(bio); 464 goto zero_tail; 465 } 466 if (dio->flags & IOMAP_DIO_WRITE) 467 task_io_account_write(n); 468 else if (dio->flags & IOMAP_DIO_DIRTY) 469 bio_set_pages_dirty(bio); 470 471 dio->size += n; 472 copied += n; 473 474 nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, 475 BIO_MAX_VECS); 476 /* 477 * We can only poll for single bio I/Os. 478 */ 479 if (nr_pages) 480 dio->iocb->ki_flags &= ~IOCB_HIPRI; 481 iomap_dio_submit_bio(iter, dio, bio, pos); 482 pos += n; 483 } while (nr_pages); 484 485 /* 486 * We need to zeroout the tail of a sub-block write if the extent type 487 * requires zeroing or the write extends beyond EOF. If we don't zero 488 * the block tail in the latter case, we can expose stale data via mmap 489 * reads of the EOF block. 490 */ 491 zero_tail: 492 if (need_zeroout || 493 ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) { 494 /* zero out from the end of the write to the end of the block */ 495 pad = pos & (fs_block_size - 1); 496 if (pad) 497 ret = iomap_dio_zero(iter, dio, pos, 498 fs_block_size - pad); 499 } 500 out: 501 /* Undo iter limitation to current extent */ 502 iov_iter_reexpand(dio->submit.iter, orig_count - copied); 503 if (copied) 504 return iomap_iter_advance(iter, &copied); 505 return ret; 506 } 507 508 static int iomap_dio_hole_iter(struct iomap_iter *iter, struct iomap_dio *dio) 509 { 510 loff_t length = iov_iter_zero(iomap_length(iter), dio->submit.iter); 511 512 dio->size += length; 513 if (!length) 514 return -EFAULT; 515 return iomap_iter_advance(iter, &length); 516 } 517 518 static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio) 519 { 520 const struct iomap *iomap = &iomi->iomap; 521 struct iov_iter *iter = dio->submit.iter; 522 void *inline_data = iomap_inline_data(iomap, iomi->pos); 523 loff_t length = iomap_length(iomi); 524 loff_t pos = iomi->pos; 525 u64 copied; 526 527 if (WARN_ON_ONCE(!iomap_inline_data_valid(iomap))) 528 return -EIO; 529 530 if (dio->flags & IOMAP_DIO_WRITE) { 531 loff_t size = iomi->inode->i_size; 532 533 if (pos > size) 534 memset(iomap_inline_data(iomap, size), 0, pos - size); 535 copied = copy_from_iter(inline_data, length, iter); 536 if (copied) { 537 if (pos + copied > size) 538 i_size_write(iomi->inode, pos + copied); 539 mark_inode_dirty(iomi->inode); 540 } 541 } else { 542 copied = copy_to_iter(inline_data, length, iter); 543 } 544 dio->size += copied; 545 if (!copied) 546 return -EFAULT; 547 return iomap_iter_advance(iomi, &copied); 548 } 549 550 static int iomap_dio_iter(struct iomap_iter *iter, struct iomap_dio *dio) 551 { 552 switch (iter->iomap.type) { 553 case IOMAP_HOLE: 554 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE)) 555 return -EIO; 556 return iomap_dio_hole_iter(iter, dio); 557 case IOMAP_UNWRITTEN: 558 if (!(dio->flags & IOMAP_DIO_WRITE)) 559 return iomap_dio_hole_iter(iter, dio); 560 return iomap_dio_bio_iter(iter, dio); 561 case IOMAP_MAPPED: 562 return iomap_dio_bio_iter(iter, dio); 563 case IOMAP_INLINE: 564 return iomap_dio_inline_iter(iter, dio); 565 case IOMAP_DELALLOC: 566 /* 567 * DIO is not serialised against mmap() access at all, and so 568 * if the page_mkwrite occurs between the writeback and the 569 * iomap_iter() call in the DIO path, then it will see the 570 * DELALLOC block that the page-mkwrite allocated. 571 */ 572 pr_warn_ratelimited("Direct I/O collision with buffered writes! File: %pD4 Comm: %.20s\n", 573 dio->iocb->ki_filp, current->comm); 574 return -EIO; 575 default: 576 WARN_ON_ONCE(1); 577 return -EIO; 578 } 579 } 580 581 /* 582 * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO 583 * is being issued as AIO or not. This allows us to optimise pure data writes 584 * to use REQ_FUA rather than requiring generic_write_sync() to issue a 585 * REQ_FLUSH post write. This is slightly tricky because a single request here 586 * can be mapped into multiple disjoint IOs and only a subset of the IOs issued 587 * may be pure data writes. In that case, we still need to do a full data sync 588 * completion. 589 * 590 * When page faults are disabled and @dio_flags includes IOMAP_DIO_PARTIAL, 591 * __iomap_dio_rw can return a partial result if it encounters a non-resident 592 * page in @iter after preparing a transfer. In that case, the non-resident 593 * pages can be faulted in and the request resumed with @done_before set to the 594 * number of bytes previously transferred. The request will then complete with 595 * the correct total number of bytes transferred; this is essential for 596 * completing partial requests asynchronously. 597 * 598 * Returns -ENOTBLK In case of a page invalidation invalidation failure for 599 * writes. The callers needs to fall back to buffered I/O in this case. 600 */ 601 struct iomap_dio * 602 __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, 603 const struct iomap_ops *ops, const struct iomap_dio_ops *dops, 604 unsigned int dio_flags, void *private, size_t done_before) 605 { 606 struct inode *inode = file_inode(iocb->ki_filp); 607 struct iomap_iter iomi = { 608 .inode = inode, 609 .pos = iocb->ki_pos, 610 .len = iov_iter_count(iter), 611 .flags = IOMAP_DIRECT, 612 .private = private, 613 }; 614 bool wait_for_completion = 615 is_sync_kiocb(iocb) || (dio_flags & IOMAP_DIO_FORCE_WAIT); 616 struct blk_plug plug; 617 struct iomap_dio *dio; 618 loff_t ret = 0; 619 620 trace_iomap_dio_rw_begin(iocb, iter, dio_flags, done_before); 621 622 if (!iomi.len) 623 return NULL; 624 625 dio = kmalloc(sizeof(*dio), GFP_KERNEL); 626 if (!dio) 627 return ERR_PTR(-ENOMEM); 628 629 dio->iocb = iocb; 630 atomic_set(&dio->ref, 1); 631 dio->size = 0; 632 dio->i_size = i_size_read(inode); 633 dio->dops = dops; 634 dio->error = 0; 635 dio->flags = 0; 636 dio->done_before = done_before; 637 638 dio->submit.iter = iter; 639 dio->submit.waiter = current; 640 641 if (iocb->ki_flags & IOCB_NOWAIT) 642 iomi.flags |= IOMAP_NOWAIT; 643 644 if (iov_iter_rw(iter) == READ) { 645 /* reads can always complete inline */ 646 dio->flags |= IOMAP_DIO_INLINE_COMP; 647 648 if (iomi.pos >= dio->i_size) 649 goto out_free_dio; 650 651 if (user_backed_iter(iter)) 652 dio->flags |= IOMAP_DIO_DIRTY; 653 654 ret = kiocb_write_and_wait(iocb, iomi.len); 655 if (ret) 656 goto out_free_dio; 657 } else { 658 iomi.flags |= IOMAP_WRITE; 659 dio->flags |= IOMAP_DIO_WRITE; 660 661 /* 662 * Flag as supporting deferred completions, if the issuer 663 * groks it. This can avoid a workqueue punt for writes. 664 * We may later clear this flag if we need to do other IO 665 * as part of this IO completion. 666 */ 667 if (iocb->ki_flags & IOCB_DIO_CALLER_COMP) 668 dio->flags |= IOMAP_DIO_CALLER_COMP; 669 670 if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) { 671 ret = -EAGAIN; 672 if (iomi.pos >= dio->i_size || 673 iomi.pos + iomi.len > dio->i_size) 674 goto out_free_dio; 675 iomi.flags |= IOMAP_OVERWRITE_ONLY; 676 } 677 678 if (iocb->ki_flags & IOCB_ATOMIC) 679 iomi.flags |= IOMAP_ATOMIC; 680 681 /* for data sync or sync, we need sync completion processing */ 682 if (iocb_is_dsync(iocb)) { 683 dio->flags |= IOMAP_DIO_NEED_SYNC; 684 685 /* 686 * For datasync only writes, we optimistically try using 687 * WRITE_THROUGH for this IO. This flag requires either 688 * FUA writes through the device's write cache, or a 689 * normal write to a device without a volatile write 690 * cache. For the former, Any non-FUA write that occurs 691 * will clear this flag, hence we know before completion 692 * whether a cache flush is necessary. 693 */ 694 if (!(iocb->ki_flags & IOCB_SYNC)) 695 dio->flags |= IOMAP_DIO_WRITE_THROUGH; 696 } 697 698 /* 699 * Try to invalidate cache pages for the range we are writing. 700 * If this invalidation fails, let the caller fall back to 701 * buffered I/O. 702 */ 703 ret = kiocb_invalidate_pages(iocb, iomi.len); 704 if (ret) { 705 if (ret != -EAGAIN) { 706 trace_iomap_dio_invalidate_fail(inode, iomi.pos, 707 iomi.len); 708 if (iocb->ki_flags & IOCB_ATOMIC) { 709 /* 710 * folio invalidation failed, maybe 711 * this is transient, unlock and see if 712 * the caller tries again. 713 */ 714 ret = -EAGAIN; 715 } else { 716 /* fall back to buffered write */ 717 ret = -ENOTBLK; 718 } 719 } 720 goto out_free_dio; 721 } 722 723 if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) { 724 ret = sb_init_dio_done_wq(inode->i_sb); 725 if (ret < 0) 726 goto out_free_dio; 727 } 728 } 729 730 inode_dio_begin(inode); 731 732 blk_start_plug(&plug); 733 while ((ret = iomap_iter(&iomi, ops)) > 0) { 734 iomi.status = iomap_dio_iter(&iomi, dio); 735 736 /* 737 * We can only poll for single bio I/Os. 738 */ 739 iocb->ki_flags &= ~IOCB_HIPRI; 740 } 741 742 blk_finish_plug(&plug); 743 744 /* 745 * We only report that we've read data up to i_size. 746 * Revert iter to a state corresponding to that as some callers (such 747 * as the splice code) rely on it. 748 */ 749 if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size) 750 iov_iter_revert(iter, iomi.pos - dio->i_size); 751 752 if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) { 753 if (!(iocb->ki_flags & IOCB_NOWAIT)) 754 wait_for_completion = true; 755 ret = 0; 756 } 757 758 /* magic error code to fall back to buffered I/O */ 759 if (ret == -ENOTBLK) { 760 wait_for_completion = true; 761 ret = 0; 762 } 763 if (ret < 0) 764 iomap_dio_set_error(dio, ret); 765 766 /* 767 * If all the writes we issued were already written through to the 768 * media, we don't need to flush the cache on IO completion. Clear the 769 * sync flag for this case. 770 */ 771 if (dio->flags & IOMAP_DIO_WRITE_THROUGH) 772 dio->flags &= ~IOMAP_DIO_NEED_SYNC; 773 774 /* 775 * We are about to drop our additional submission reference, which 776 * might be the last reference to the dio. There are three different 777 * ways we can progress here: 778 * 779 * (a) If this is the last reference we will always complete and free 780 * the dio ourselves. 781 * (b) If this is not the last reference, and we serve an asynchronous 782 * iocb, we must never touch the dio after the decrement, the 783 * I/O completion handler will complete and free it. 784 * (c) If this is not the last reference, but we serve a synchronous 785 * iocb, the I/O completion handler will wake us up on the drop 786 * of the final reference, and we will complete and free it here 787 * after we got woken by the I/O completion handler. 788 */ 789 dio->wait_for_completion = wait_for_completion; 790 if (!atomic_dec_and_test(&dio->ref)) { 791 if (!wait_for_completion) { 792 trace_iomap_dio_rw_queued(inode, iomi.pos, iomi.len); 793 return ERR_PTR(-EIOCBQUEUED); 794 } 795 796 for (;;) { 797 set_current_state(TASK_UNINTERRUPTIBLE); 798 if (!READ_ONCE(dio->submit.waiter)) 799 break; 800 801 blk_io_schedule(); 802 } 803 __set_current_state(TASK_RUNNING); 804 } 805 806 return dio; 807 808 out_free_dio: 809 kfree(dio); 810 if (ret) 811 return ERR_PTR(ret); 812 return NULL; 813 } 814 EXPORT_SYMBOL_GPL(__iomap_dio_rw); 815 816 ssize_t 817 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, 818 const struct iomap_ops *ops, const struct iomap_dio_ops *dops, 819 unsigned int dio_flags, void *private, size_t done_before) 820 { 821 struct iomap_dio *dio; 822 823 dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags, private, 824 done_before); 825 if (IS_ERR_OR_NULL(dio)) 826 return PTR_ERR_OR_ZERO(dio); 827 return iomap_dio_complete(dio); 828 } 829 EXPORT_SYMBOL_GPL(iomap_dio_rw); 830 831 static int __init iomap_dio_init(void) 832 { 833 zero_page = alloc_pages(GFP_KERNEL | __GFP_ZERO, 834 IOMAP_ZERO_PAGE_ORDER); 835 836 if (!zero_page) 837 return -ENOMEM; 838 839 return 0; 840 } 841 fs_initcall(iomap_dio_init); 842