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