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