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 iov_iter iter; 205 struct bio *bio; 206 bool need_zeroout = false; 207 bool use_fua = false; 208 int nr_pages, ret = 0; 209 size_t copied = 0; 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 * Operate on a partial iter trimmed to the extent we were called for. 240 * We'll update the iter in the dio once we're done with this extent. 241 */ 242 iter = *dio->submit.iter; 243 iov_iter_truncate(&iter, length); 244 245 nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES); 246 if (nr_pages <= 0) 247 return nr_pages; 248 249 if (need_zeroout) { 250 /* zero out from the start of the block to the write offset */ 251 pad = pos & (fs_block_size - 1); 252 if (pad) 253 iomap_dio_zero(dio, iomap, pos - pad, pad); 254 } 255 256 do { 257 size_t n; 258 if (dio->error) { 259 iov_iter_revert(dio->submit.iter, copied); 260 return 0; 261 } 262 263 bio = bio_alloc(GFP_KERNEL, nr_pages); 264 bio_set_dev(bio, iomap->bdev); 265 bio->bi_iter.bi_sector = iomap_sector(iomap, pos); 266 bio->bi_write_hint = dio->iocb->ki_hint; 267 bio->bi_ioprio = dio->iocb->ki_ioprio; 268 bio->bi_private = dio; 269 bio->bi_end_io = iomap_dio_bio_end_io; 270 271 ret = bio_iov_iter_get_pages(bio, &iter); 272 if (unlikely(ret)) { 273 /* 274 * We have to stop part way through an IO. We must fall 275 * through to the sub-block tail zeroing here, otherwise 276 * this short IO may expose stale data in the tail of 277 * the block we haven't written data to. 278 */ 279 bio_put(bio); 280 goto zero_tail; 281 } 282 283 n = bio->bi_iter.bi_size; 284 if (dio->flags & IOMAP_DIO_WRITE) { 285 bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; 286 if (use_fua) 287 bio->bi_opf |= REQ_FUA; 288 else 289 dio->flags &= ~IOMAP_DIO_WRITE_FUA; 290 task_io_account_write(n); 291 } else { 292 bio->bi_opf = REQ_OP_READ; 293 if (dio->flags & IOMAP_DIO_DIRTY) 294 bio_set_pages_dirty(bio); 295 } 296 297 iov_iter_advance(dio->submit.iter, n); 298 299 dio->size += n; 300 pos += n; 301 copied += n; 302 303 nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES); 304 iomap_dio_submit_bio(dio, iomap, bio); 305 } while (nr_pages); 306 307 /* 308 * We need to zeroout the tail of a sub-block write if the extent type 309 * requires zeroing or the write extends beyond EOF. If we don't zero 310 * the block tail in the latter case, we can expose stale data via mmap 311 * reads of the EOF block. 312 */ 313 zero_tail: 314 if (need_zeroout || 315 ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) { 316 /* zero out from the end of the write to the end of the block */ 317 pad = pos & (fs_block_size - 1); 318 if (pad) 319 iomap_dio_zero(dio, iomap, pos, fs_block_size - pad); 320 } 321 return copied ? copied : ret; 322 } 323 324 static loff_t 325 iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio) 326 { 327 length = iov_iter_zero(length, dio->submit.iter); 328 dio->size += length; 329 return length; 330 } 331 332 static loff_t 333 iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length, 334 struct iomap_dio *dio, struct iomap *iomap) 335 { 336 struct iov_iter *iter = dio->submit.iter; 337 size_t copied; 338 339 BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data)); 340 341 if (dio->flags & IOMAP_DIO_WRITE) { 342 loff_t size = inode->i_size; 343 344 if (pos > size) 345 memset(iomap->inline_data + size, 0, pos - size); 346 copied = copy_from_iter(iomap->inline_data + pos, length, iter); 347 if (copied) { 348 if (pos + copied > size) 349 i_size_write(inode, pos + copied); 350 mark_inode_dirty(inode); 351 } 352 } else { 353 copied = copy_to_iter(iomap->inline_data + pos, length, iter); 354 } 355 dio->size += copied; 356 return copied; 357 } 358 359 static loff_t 360 iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, 361 void *data, struct iomap *iomap) 362 { 363 struct iomap_dio *dio = data; 364 365 switch (iomap->type) { 366 case IOMAP_HOLE: 367 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE)) 368 return -EIO; 369 return iomap_dio_hole_actor(length, dio); 370 case IOMAP_UNWRITTEN: 371 if (!(dio->flags & IOMAP_DIO_WRITE)) 372 return iomap_dio_hole_actor(length, dio); 373 return iomap_dio_bio_actor(inode, pos, length, dio, iomap); 374 case IOMAP_MAPPED: 375 return iomap_dio_bio_actor(inode, pos, length, dio, iomap); 376 case IOMAP_INLINE: 377 return iomap_dio_inline_actor(inode, pos, length, dio, iomap); 378 default: 379 WARN_ON_ONCE(1); 380 return -EIO; 381 } 382 } 383 384 /* 385 * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO 386 * is being issued as AIO or not. This allows us to optimise pure data writes 387 * to use REQ_FUA rather than requiring generic_write_sync() to issue a 388 * REQ_FLUSH post write. This is slightly tricky because a single request here 389 * can be mapped into multiple disjoint IOs and only a subset of the IOs issued 390 * may be pure data writes. In that case, we still need to do a full data sync 391 * completion. 392 */ 393 ssize_t 394 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, 395 const struct iomap_ops *ops, const struct iomap_dio_ops *dops) 396 { 397 struct address_space *mapping = iocb->ki_filp->f_mapping; 398 struct inode *inode = file_inode(iocb->ki_filp); 399 size_t count = iov_iter_count(iter); 400 loff_t pos = iocb->ki_pos, start = pos; 401 loff_t end = iocb->ki_pos + count - 1, ret = 0; 402 unsigned int flags = IOMAP_DIRECT; 403 bool wait_for_completion = is_sync_kiocb(iocb); 404 struct blk_plug plug; 405 struct iomap_dio *dio; 406 407 lockdep_assert_held(&inode->i_rwsem); 408 409 if (!count) 410 return 0; 411 412 dio = kmalloc(sizeof(*dio), GFP_KERNEL); 413 if (!dio) 414 return -ENOMEM; 415 416 dio->iocb = iocb; 417 atomic_set(&dio->ref, 1); 418 dio->size = 0; 419 dio->i_size = i_size_read(inode); 420 dio->dops = dops; 421 dio->error = 0; 422 dio->flags = 0; 423 424 dio->submit.iter = iter; 425 dio->submit.waiter = current; 426 dio->submit.cookie = BLK_QC_T_NONE; 427 dio->submit.last_queue = NULL; 428 429 if (iov_iter_rw(iter) == READ) { 430 if (pos >= dio->i_size) 431 goto out_free_dio; 432 433 if (iter_is_iovec(iter) && iov_iter_rw(iter) == READ) 434 dio->flags |= IOMAP_DIO_DIRTY; 435 } else { 436 flags |= IOMAP_WRITE; 437 dio->flags |= IOMAP_DIO_WRITE; 438 439 /* for data sync or sync, we need sync completion processing */ 440 if (iocb->ki_flags & IOCB_DSYNC) 441 dio->flags |= IOMAP_DIO_NEED_SYNC; 442 443 /* 444 * For datasync only writes, we optimistically try using FUA for 445 * this IO. Any non-FUA write that occurs will clear this flag, 446 * hence we know before completion whether a cache flush is 447 * necessary. 448 */ 449 if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC) 450 dio->flags |= IOMAP_DIO_WRITE_FUA; 451 } 452 453 if (iocb->ki_flags & IOCB_NOWAIT) { 454 if (filemap_range_has_page(mapping, start, end)) { 455 ret = -EAGAIN; 456 goto out_free_dio; 457 } 458 flags |= IOMAP_NOWAIT; 459 } 460 461 ret = filemap_write_and_wait_range(mapping, start, end); 462 if (ret) 463 goto out_free_dio; 464 465 /* 466 * Try to invalidate cache pages for the range we're direct 467 * writing. If this invalidation fails, tough, the write will 468 * still work, but racing two incompatible write paths is a 469 * pretty crazy thing to do, so we don't support it 100%. 470 */ 471 ret = invalidate_inode_pages2_range(mapping, 472 start >> PAGE_SHIFT, end >> PAGE_SHIFT); 473 if (ret) 474 dio_warn_stale_pagecache(iocb->ki_filp); 475 ret = 0; 476 477 if (iov_iter_rw(iter) == WRITE && !wait_for_completion && 478 !inode->i_sb->s_dio_done_wq) { 479 ret = sb_init_dio_done_wq(inode->i_sb); 480 if (ret < 0) 481 goto out_free_dio; 482 } 483 484 inode_dio_begin(inode); 485 486 blk_start_plug(&plug); 487 do { 488 ret = iomap_apply(inode, pos, count, flags, ops, dio, 489 iomap_dio_actor); 490 if (ret <= 0) { 491 /* magic error code to fall back to buffered I/O */ 492 if (ret == -ENOTBLK) { 493 wait_for_completion = true; 494 ret = 0; 495 } 496 break; 497 } 498 pos += ret; 499 500 if (iov_iter_rw(iter) == READ && pos >= dio->i_size) 501 break; 502 } while ((count = iov_iter_count(iter)) > 0); 503 blk_finish_plug(&plug); 504 505 if (ret < 0) 506 iomap_dio_set_error(dio, ret); 507 508 /* 509 * If all the writes we issued were FUA, we don't need to flush the 510 * cache on IO completion. Clear the sync flag for this case. 511 */ 512 if (dio->flags & IOMAP_DIO_WRITE_FUA) 513 dio->flags &= ~IOMAP_DIO_NEED_SYNC; 514 515 WRITE_ONCE(iocb->ki_cookie, dio->submit.cookie); 516 WRITE_ONCE(iocb->private, dio->submit.last_queue); 517 518 /* 519 * We are about to drop our additional submission reference, which 520 * might be the last reference to the dio. There are three three 521 * different ways we can progress here: 522 * 523 * (a) If this is the last reference we will always complete and free 524 * the dio ourselves. 525 * (b) If this is not the last reference, and we serve an asynchronous 526 * iocb, we must never touch the dio after the decrement, the 527 * I/O completion handler will complete and free it. 528 * (c) If this is not the last reference, but we serve a synchronous 529 * iocb, the I/O completion handler will wake us up on the drop 530 * of the final reference, and we will complete and free it here 531 * after we got woken by the I/O completion handler. 532 */ 533 dio->wait_for_completion = wait_for_completion; 534 if (!atomic_dec_and_test(&dio->ref)) { 535 if (!wait_for_completion) 536 return -EIOCBQUEUED; 537 538 for (;;) { 539 set_current_state(TASK_UNINTERRUPTIBLE); 540 if (!READ_ONCE(dio->submit.waiter)) 541 break; 542 543 if (!(iocb->ki_flags & IOCB_HIPRI) || 544 !dio->submit.last_queue || 545 !blk_poll(dio->submit.last_queue, 546 dio->submit.cookie, true)) 547 io_schedule(); 548 } 549 __set_current_state(TASK_RUNNING); 550 } 551 552 return iomap_dio_complete(dio); 553 554 out_free_dio: 555 kfree(dio); 556 return ret; 557 } 558 EXPORT_SYMBOL_GPL(iomap_dio_rw); 559