1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2010 Red Hat, Inc. 4 * Copyright (c) 2016-2018 Christoph Hellwig. 5 */ 6 #include <linux/module.h> 7 #include <linux/compiler.h> 8 #include <linux/fs.h> 9 #include <linux/iomap.h> 10 #include <linux/backing-dev.h> 11 #include <linux/uio.h> 12 #include <linux/task_io_accounting_ops.h> 13 #include "trace.h" 14 15 #include "../internal.h" 16 17 /* 18 * Private flags for iomap_dio, must not overlap with the public ones in 19 * iomap.h: 20 */ 21 #define IOMAP_DIO_WRITE_FUA (1 << 28) 22 #define IOMAP_DIO_NEED_SYNC (1 << 29) 23 #define IOMAP_DIO_WRITE (1 << 30) 24 #define IOMAP_DIO_DIRTY (1 << 31) 25 26 struct iomap_dio { 27 struct kiocb *iocb; 28 const struct iomap_dio_ops *dops; 29 loff_t i_size; 30 loff_t size; 31 atomic_t ref; 32 unsigned flags; 33 int error; 34 bool wait_for_completion; 35 36 union { 37 /* used during submission and for synchronous completion: */ 38 struct { 39 struct iov_iter *iter; 40 struct task_struct *waiter; 41 struct request_queue *last_queue; 42 blk_qc_t cookie; 43 } submit; 44 45 /* used for aio completion: */ 46 struct { 47 struct work_struct work; 48 } aio; 49 }; 50 }; 51 52 int iomap_dio_iopoll(struct kiocb *kiocb, bool spin) 53 { 54 struct request_queue *q = READ_ONCE(kiocb->private); 55 56 if (!q) 57 return 0; 58 return blk_poll(q, READ_ONCE(kiocb->ki_cookie), spin); 59 } 60 EXPORT_SYMBOL_GPL(iomap_dio_iopoll); 61 62 static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap, 63 struct bio *bio, loff_t pos) 64 { 65 atomic_inc(&dio->ref); 66 67 if (dio->iocb->ki_flags & IOCB_HIPRI) 68 bio_set_polled(bio, dio->iocb); 69 70 dio->submit.last_queue = bdev_get_queue(iomap->bdev); 71 if (dio->dops && dio->dops->submit_io) 72 dio->submit.cookie = dio->dops->submit_io( 73 file_inode(dio->iocb->ki_filp), 74 iomap, bio, pos); 75 else 76 dio->submit.cookie = submit_bio(bio); 77 } 78 79 static ssize_t iomap_dio_complete(struct iomap_dio *dio) 80 { 81 const struct iomap_dio_ops *dops = dio->dops; 82 struct kiocb *iocb = dio->iocb; 83 struct inode *inode = file_inode(iocb->ki_filp); 84 loff_t offset = iocb->ki_pos; 85 ssize_t ret = dio->error; 86 87 if (dops && dops->end_io) 88 ret = dops->end_io(iocb, dio->size, ret, dio->flags); 89 90 if (likely(!ret)) { 91 ret = dio->size; 92 /* check for short read */ 93 if (offset + ret > dio->i_size && 94 !(dio->flags & IOMAP_DIO_WRITE)) 95 ret = dio->i_size - offset; 96 iocb->ki_pos += ret; 97 } 98 99 /* 100 * Try again to invalidate clean pages which might have been cached by 101 * non-direct readahead, or faulted in by get_user_pages() if the source 102 * of the write was an mmap'ed region of the file we're writing. Either 103 * one is a pretty crazy thing to do, so we don't support it 100%. If 104 * this invalidation fails, tough, the write still worked... 105 * 106 * And this page cache invalidation has to be after ->end_io(), as some 107 * filesystems convert unwritten extents to real allocations in 108 * ->end_io() when necessary, otherwise a racing buffer read would cache 109 * zeros from unwritten extents. 110 */ 111 if (!dio->error && 112 (dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) { 113 int err; 114 err = invalidate_inode_pages2_range(inode->i_mapping, 115 offset >> PAGE_SHIFT, 116 (offset + dio->size - 1) >> PAGE_SHIFT); 117 if (err) 118 dio_warn_stale_pagecache(iocb->ki_filp); 119 } 120 121 /* 122 * If this is a DSYNC write, make sure we push it to stable storage now 123 * that we've written data. 124 */ 125 if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC)) 126 ret = generic_write_sync(iocb, ret); 127 128 inode_dio_end(file_inode(iocb->ki_filp)); 129 kfree(dio); 130 131 return ret; 132 } 133 134 static void iomap_dio_complete_work(struct work_struct *work) 135 { 136 struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work); 137 struct kiocb *iocb = dio->iocb; 138 139 iocb->ki_complete(iocb, iomap_dio_complete(dio), 0); 140 } 141 142 /* 143 * Set an error in the dio if none is set yet. We have to use cmpxchg 144 * as the submission context and the completion context(s) can race to 145 * update the error. 146 */ 147 static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret) 148 { 149 cmpxchg(&dio->error, 0, ret); 150 } 151 152 static void iomap_dio_bio_end_io(struct bio *bio) 153 { 154 struct iomap_dio *dio = bio->bi_private; 155 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY); 156 157 if (bio->bi_status) 158 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status)); 159 160 if (atomic_dec_and_test(&dio->ref)) { 161 if (dio->wait_for_completion) { 162 struct task_struct *waiter = dio->submit.waiter; 163 WRITE_ONCE(dio->submit.waiter, NULL); 164 blk_wake_io_task(waiter); 165 } else if (dio->flags & IOMAP_DIO_WRITE) { 166 struct inode *inode = file_inode(dio->iocb->ki_filp); 167 168 INIT_WORK(&dio->aio.work, iomap_dio_complete_work); 169 queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work); 170 } else { 171 iomap_dio_complete_work(&dio->aio.work); 172 } 173 } 174 175 if (should_dirty) { 176 bio_check_pages_dirty(bio); 177 } else { 178 bio_release_pages(bio, false); 179 bio_put(bio); 180 } 181 } 182 183 static void 184 iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos, 185 unsigned len) 186 { 187 struct page *page = ZERO_PAGE(0); 188 int flags = REQ_SYNC | REQ_IDLE; 189 struct bio *bio; 190 191 bio = bio_alloc(GFP_KERNEL, 1); 192 bio_set_dev(bio, iomap->bdev); 193 bio->bi_iter.bi_sector = iomap_sector(iomap, pos); 194 bio->bi_private = dio; 195 bio->bi_end_io = iomap_dio_bio_end_io; 196 197 get_page(page); 198 __bio_add_page(bio, page, len, 0); 199 bio_set_op_attrs(bio, REQ_OP_WRITE, flags); 200 iomap_dio_submit_bio(dio, iomap, bio, pos); 201 } 202 203 static loff_t 204 iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, 205 struct iomap_dio *dio, struct iomap *iomap) 206 { 207 unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev)); 208 unsigned int fs_block_size = i_blocksize(inode), pad; 209 unsigned int align = iov_iter_alignment(dio->submit.iter); 210 struct bio *bio; 211 bool need_zeroout = false; 212 bool use_fua = false; 213 int nr_pages, ret = 0; 214 size_t copied = 0; 215 size_t orig_count; 216 217 if ((pos | length | align) & ((1 << blkbits) - 1)) 218 return -EINVAL; 219 220 if (iomap->type == IOMAP_UNWRITTEN) { 221 dio->flags |= IOMAP_DIO_UNWRITTEN; 222 need_zeroout = true; 223 } 224 225 if (iomap->flags & IOMAP_F_SHARED) 226 dio->flags |= IOMAP_DIO_COW; 227 228 if (iomap->flags & IOMAP_F_NEW) { 229 need_zeroout = true; 230 } else if (iomap->type == IOMAP_MAPPED) { 231 /* 232 * Use a FUA write if we need datasync semantics, this is a pure 233 * data IO that doesn't require any metadata updates (including 234 * after IO completion such as unwritten extent conversion) and 235 * the underlying device supports FUA. This allows us to avoid 236 * cache flushes on IO completion. 237 */ 238 if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) && 239 (dio->flags & IOMAP_DIO_WRITE_FUA) && 240 blk_queue_fua(bdev_get_queue(iomap->bdev))) 241 use_fua = true; 242 } 243 244 /* 245 * Save the original count and trim the iter to just the extent we 246 * are operating on right now. The iter will be re-expanded once 247 * we are done. 248 */ 249 orig_count = iov_iter_count(dio->submit.iter); 250 iov_iter_truncate(dio->submit.iter, length); 251 252 nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES); 253 if (nr_pages <= 0) { 254 ret = nr_pages; 255 goto out; 256 } 257 258 if (need_zeroout) { 259 /* zero out from the start of the block to the write offset */ 260 pad = pos & (fs_block_size - 1); 261 if (pad) 262 iomap_dio_zero(dio, iomap, pos - pad, pad); 263 } 264 265 do { 266 size_t n; 267 if (dio->error) { 268 iov_iter_revert(dio->submit.iter, copied); 269 copied = ret = 0; 270 goto out; 271 } 272 273 bio = bio_alloc(GFP_KERNEL, nr_pages); 274 bio_set_dev(bio, iomap->bdev); 275 bio->bi_iter.bi_sector = iomap_sector(iomap, pos); 276 bio->bi_write_hint = dio->iocb->ki_hint; 277 bio->bi_ioprio = dio->iocb->ki_ioprio; 278 bio->bi_private = dio; 279 bio->bi_end_io = iomap_dio_bio_end_io; 280 281 ret = bio_iov_iter_get_pages(bio, dio->submit.iter); 282 if (unlikely(ret)) { 283 /* 284 * We have to stop part way through an IO. We must fall 285 * through to the sub-block tail zeroing here, otherwise 286 * this short IO may expose stale data in the tail of 287 * the block we haven't written data to. 288 */ 289 bio_put(bio); 290 goto zero_tail; 291 } 292 293 n = bio->bi_iter.bi_size; 294 if (dio->flags & IOMAP_DIO_WRITE) { 295 bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; 296 if (use_fua) 297 bio->bi_opf |= REQ_FUA; 298 else 299 dio->flags &= ~IOMAP_DIO_WRITE_FUA; 300 task_io_account_write(n); 301 } else { 302 bio->bi_opf = REQ_OP_READ; 303 if (dio->flags & IOMAP_DIO_DIRTY) 304 bio_set_pages_dirty(bio); 305 } 306 307 dio->size += n; 308 copied += n; 309 310 nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES); 311 iomap_dio_submit_bio(dio, iomap, bio, pos); 312 pos += n; 313 } while (nr_pages); 314 315 /* 316 * We need to zeroout the tail of a sub-block write if the extent type 317 * requires zeroing or the write extends beyond EOF. If we don't zero 318 * the block tail in the latter case, we can expose stale data via mmap 319 * reads of the EOF block. 320 */ 321 zero_tail: 322 if (need_zeroout || 323 ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) { 324 /* zero out from the end of the write to the end of the block */ 325 pad = pos & (fs_block_size - 1); 326 if (pad) 327 iomap_dio_zero(dio, iomap, pos, fs_block_size - pad); 328 } 329 out: 330 /* Undo iter limitation to current extent */ 331 iov_iter_reexpand(dio->submit.iter, orig_count - copied); 332 if (copied) 333 return copied; 334 return ret; 335 } 336 337 static loff_t 338 iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio) 339 { 340 length = iov_iter_zero(length, dio->submit.iter); 341 dio->size += length; 342 return length; 343 } 344 345 static loff_t 346 iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length, 347 struct iomap_dio *dio, struct iomap *iomap) 348 { 349 struct iov_iter *iter = dio->submit.iter; 350 size_t copied; 351 352 BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data)); 353 354 if (dio->flags & IOMAP_DIO_WRITE) { 355 loff_t size = inode->i_size; 356 357 if (pos > size) 358 memset(iomap->inline_data + size, 0, pos - size); 359 copied = copy_from_iter(iomap->inline_data + pos, length, iter); 360 if (copied) { 361 if (pos + copied > size) 362 i_size_write(inode, pos + copied); 363 mark_inode_dirty(inode); 364 } 365 } else { 366 copied = copy_to_iter(iomap->inline_data + pos, length, iter); 367 } 368 dio->size += copied; 369 return copied; 370 } 371 372 static loff_t 373 iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 374 void *data, struct iomap *iomap, struct iomap *srcmap) 375 { 376 struct iomap_dio *dio = data; 377 378 switch (iomap->type) { 379 case IOMAP_HOLE: 380 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE)) 381 return -EIO; 382 return iomap_dio_hole_actor(length, dio); 383 case IOMAP_UNWRITTEN: 384 if (!(dio->flags & IOMAP_DIO_WRITE)) 385 return iomap_dio_hole_actor(length, dio); 386 return iomap_dio_bio_actor(inode, pos, length, dio, iomap); 387 case IOMAP_MAPPED: 388 return iomap_dio_bio_actor(inode, pos, length, dio, iomap); 389 case IOMAP_INLINE: 390 return iomap_dio_inline_actor(inode, pos, length, dio, iomap); 391 default: 392 WARN_ON_ONCE(1); 393 return -EIO; 394 } 395 } 396 397 /* 398 * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO 399 * is being issued as AIO or not. This allows us to optimise pure data writes 400 * to use REQ_FUA rather than requiring generic_write_sync() to issue a 401 * REQ_FLUSH post write. This is slightly tricky because a single request here 402 * can be mapped into multiple disjoint IOs and only a subset of the IOs issued 403 * may be pure data writes. In that case, we still need to do a full data sync 404 * completion. 405 * 406 * Returns -ENOTBLK In case of a page invalidation invalidation failure for 407 * writes. The callers needs to fall back to buffered I/O in this case. 408 */ 409 ssize_t 410 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, 411 const struct iomap_ops *ops, const struct iomap_dio_ops *dops, 412 bool wait_for_completion) 413 { 414 struct address_space *mapping = iocb->ki_filp->f_mapping; 415 struct inode *inode = file_inode(iocb->ki_filp); 416 size_t count = iov_iter_count(iter); 417 loff_t pos = iocb->ki_pos; 418 loff_t end = iocb->ki_pos + count - 1, ret = 0; 419 unsigned int flags = IOMAP_DIRECT; 420 struct blk_plug plug; 421 struct iomap_dio *dio; 422 423 if (!count) 424 return 0; 425 426 if (WARN_ON(is_sync_kiocb(iocb) && !wait_for_completion)) 427 return -EIO; 428 429 dio = kmalloc(sizeof(*dio), GFP_KERNEL); 430 if (!dio) 431 return -ENOMEM; 432 433 dio->iocb = iocb; 434 atomic_set(&dio->ref, 1); 435 dio->size = 0; 436 dio->i_size = i_size_read(inode); 437 dio->dops = dops; 438 dio->error = 0; 439 dio->flags = 0; 440 441 dio->submit.iter = iter; 442 dio->submit.waiter = current; 443 dio->submit.cookie = BLK_QC_T_NONE; 444 dio->submit.last_queue = NULL; 445 446 if (iov_iter_rw(iter) == READ) { 447 if (pos >= dio->i_size) 448 goto out_free_dio; 449 450 if (iter_is_iovec(iter)) 451 dio->flags |= IOMAP_DIO_DIRTY; 452 } else { 453 flags |= IOMAP_WRITE; 454 dio->flags |= IOMAP_DIO_WRITE; 455 456 /* for data sync or sync, we need sync completion processing */ 457 if (iocb->ki_flags & IOCB_DSYNC) 458 dio->flags |= IOMAP_DIO_NEED_SYNC; 459 460 /* 461 * For datasync only writes, we optimistically try using FUA for 462 * this IO. Any non-FUA write that occurs will clear this flag, 463 * hence we know before completion whether a cache flush is 464 * necessary. 465 */ 466 if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC) 467 dio->flags |= IOMAP_DIO_WRITE_FUA; 468 } 469 470 if (iocb->ki_flags & IOCB_NOWAIT) { 471 if (filemap_range_has_page(mapping, pos, end)) { 472 ret = -EAGAIN; 473 goto out_free_dio; 474 } 475 flags |= IOMAP_NOWAIT; 476 } 477 478 ret = filemap_write_and_wait_range(mapping, pos, end); 479 if (ret) 480 goto out_free_dio; 481 482 if (iov_iter_rw(iter) == WRITE) { 483 /* 484 * Try to invalidate cache pages for the range we are writing. 485 * If this invalidation fails, let the caller fall back to 486 * buffered I/O. 487 */ 488 if (invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, 489 end >> PAGE_SHIFT)) { 490 trace_iomap_dio_invalidate_fail(inode, pos, count); 491 ret = -ENOTBLK; 492 goto out_free_dio; 493 } 494 495 if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) { 496 ret = sb_init_dio_done_wq(inode->i_sb); 497 if (ret < 0) 498 goto out_free_dio; 499 } 500 } 501 502 inode_dio_begin(inode); 503 504 blk_start_plug(&plug); 505 do { 506 ret = iomap_apply(inode, pos, count, flags, ops, dio, 507 iomap_dio_actor); 508 if (ret <= 0) { 509 /* magic error code to fall back to buffered I/O */ 510 if (ret == -ENOTBLK) { 511 wait_for_completion = true; 512 ret = 0; 513 } 514 break; 515 } 516 pos += ret; 517 518 if (iov_iter_rw(iter) == READ && pos >= dio->i_size) { 519 /* 520 * We only report that we've read data up to i_size. 521 * Revert iter to a state corresponding to that as 522 * some callers (such as splice code) rely on it. 523 */ 524 iov_iter_revert(iter, pos - dio->i_size); 525 break; 526 } 527 } while ((count = iov_iter_count(iter)) > 0); 528 blk_finish_plug(&plug); 529 530 if (ret < 0) 531 iomap_dio_set_error(dio, ret); 532 533 /* 534 * If all the writes we issued were FUA, we don't need to flush the 535 * cache on IO completion. Clear the sync flag for this case. 536 */ 537 if (dio->flags & IOMAP_DIO_WRITE_FUA) 538 dio->flags &= ~IOMAP_DIO_NEED_SYNC; 539 540 WRITE_ONCE(iocb->ki_cookie, dio->submit.cookie); 541 WRITE_ONCE(iocb->private, dio->submit.last_queue); 542 543 /* 544 * We are about to drop our additional submission reference, which 545 * might be the last reference to the dio. There are three different 546 * ways we can progress here: 547 * 548 * (a) If this is the last reference we will always complete and free 549 * the dio ourselves. 550 * (b) If this is not the last reference, and we serve an asynchronous 551 * iocb, we must never touch the dio after the decrement, the 552 * I/O completion handler will complete and free it. 553 * (c) If this is not the last reference, but we serve a synchronous 554 * iocb, the I/O completion handler will wake us up on the drop 555 * of the final reference, and we will complete and free it here 556 * after we got woken by the I/O completion handler. 557 */ 558 dio->wait_for_completion = wait_for_completion; 559 if (!atomic_dec_and_test(&dio->ref)) { 560 if (!wait_for_completion) 561 return -EIOCBQUEUED; 562 563 for (;;) { 564 set_current_state(TASK_UNINTERRUPTIBLE); 565 if (!READ_ONCE(dio->submit.waiter)) 566 break; 567 568 if (!(iocb->ki_flags & IOCB_HIPRI) || 569 !dio->submit.last_queue || 570 !blk_poll(dio->submit.last_queue, 571 dio->submit.cookie, true)) 572 blk_io_schedule(); 573 } 574 __set_current_state(TASK_RUNNING); 575 } 576 577 return iomap_dio_complete(dio); 578 579 out_free_dio: 580 kfree(dio); 581 return ret; 582 } 583 EXPORT_SYMBOL_GPL(iomap_dio_rw); 584