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