Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/fs/iomap.c

  1 /*
  2  * Copyright (C) 2010 Red Hat, Inc.
  3  * Copyright (c) 2016 Christoph Hellwig.
  4  *
  5  * This program is free software; you can redistribute it and/or modify it
  6  * under the terms and conditions of the GNU General Public License,
  7  * version 2, as published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 12  * more details.
 13  */
 14 #include <linux/module.h>
 15 #include <linux/compiler.h>
 16 #include <linux/fs.h>
 17 #include <linux/iomap.h>
 18 #include <linux/uaccess.h>
 19 #include <linux/gfp.h>
 20 #include <linux/mm.h>
 21 #include <linux/swap.h>
 22 #include <linux/pagemap.h>
 23 #include <linux/file.h>
 24 #include <linux/uio.h>
 25 #include <linux/backing-dev.h>
 26 #include <linux/buffer_head.h>
 27 #include <linux/task_io_accounting_ops.h>
 28 #include <linux/dax.h>
 29 #include "internal.h"
 30 
 31 /*
 32  * Execute a iomap write on a segment of the mapping that spans a
 33  * contiguous range of pages that have identical block mapping state.
 34  *
 35  * This avoids the need to map pages individually, do individual allocations
 36  * for each page and most importantly avoid the need for filesystem specific
 37  * locking per page. Instead, all the operations are amortised over the entire
 38  * range of pages. It is assumed that the filesystems will lock whatever
 39  * resources they require in the iomap_begin call, and release them in the
 40  * iomap_end call.
 41  */
 42 loff_t
 43 iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
 44                 struct iomap_ops *ops, void *data, iomap_actor_t actor)
 45 {
 46         struct iomap iomap = { 0 };
 47         loff_t written = 0, ret;
 48 
 49         /*
 50          * Need to map a range from start position for length bytes. This can
 51          * span multiple pages - it is only guaranteed to return a range of a
 52          * single type of pages (e.g. all into a hole, all mapped or all
 53          * unwritten). Failure at this point has nothing to undo.
 54          *
 55          * If allocation is required for this range, reserve the space now so
 56          * that the allocation is guaranteed to succeed later on. Once we copy
 57          * the data into the page cache pages, then we cannot fail otherwise we
 58          * expose transient stale data. If the reserve fails, we can safely
 59          * back out at this point as there is nothing to undo.
 60          */
 61         ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
 62         if (ret)
 63                 return ret;
 64         if (WARN_ON(iomap.offset > pos))
 65                 return -EIO;
 66 
 67         /*
 68          * Cut down the length to the one actually provided by the filesystem,
 69          * as it might not be able to give us the whole size that we requested.
 70          */
 71         if (iomap.offset + iomap.length < pos + length)
 72                 length = iomap.offset + iomap.length - pos;
 73 
 74         /*
 75          * Now that we have guaranteed that the space allocation will succeed.
 76          * we can do the copy-in page by page without having to worry about
 77          * failures exposing transient data.
 78          */
 79         written = actor(inode, pos, length, data, &iomap);
 80 
 81         /*
 82          * Now the data has been copied, commit the range we've copied.  This
 83          * should not fail unless the filesystem has had a fatal error.
 84          */
 85         if (ops->iomap_end) {
 86                 ret = ops->iomap_end(inode, pos, length,
 87                                      written > 0 ? written : 0,
 88                                      flags, &iomap);
 89         }
 90 
 91         return written ? written : ret;
 92 }
 93 
 94 static void
 95 iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
 96 {
 97         loff_t i_size = i_size_read(inode);
 98 
 99         /*
100          * Only truncate newly allocated pages beyoned EOF, even if the
101          * write started inside the existing inode size.
102          */
103         if (pos + len > i_size)
104                 truncate_pagecache_range(inode, max(pos, i_size), pos + len);
105 }
106 
107 static int
108 iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
109                 struct page **pagep, struct iomap *iomap)
110 {
111         pgoff_t index = pos >> PAGE_SHIFT;
112         struct page *page;
113         int status = 0;
114 
115         BUG_ON(pos + len > iomap->offset + iomap->length);
116 
117         if (fatal_signal_pending(current))
118                 return -EINTR;
119 
120         page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
121         if (!page)
122                 return -ENOMEM;
123 
124         status = __block_write_begin_int(page, pos, len, NULL, iomap);
125         if (unlikely(status)) {
126                 unlock_page(page);
127                 put_page(page);
128                 page = NULL;
129 
130                 iomap_write_failed(inode, pos, len);
131         }
132 
133         *pagep = page;
134         return status;
135 }
136 
137 static int
138 iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
139                 unsigned copied, struct page *page)
140 {
141         int ret;
142 
143         ret = generic_write_end(NULL, inode->i_mapping, pos, len,
144                         copied, page, NULL);
145         if (ret < len)
146                 iomap_write_failed(inode, pos, len);
147         return ret;
148 }
149 
150 static loff_t
151 iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
152                 struct iomap *iomap)
153 {
154         struct iov_iter *i = data;
155         long status = 0;
156         ssize_t written = 0;
157         unsigned int flags = AOP_FLAG_NOFS;
158 
159         /*
160          * Copies from kernel address space cannot fail (NFSD is a big user).
161          */
162         if (!iter_is_iovec(i))
163                 flags |= AOP_FLAG_UNINTERRUPTIBLE;
164 
165         do {
166                 struct page *page;
167                 unsigned long offset;   /* Offset into pagecache page */
168                 unsigned long bytes;    /* Bytes to write to page */
169                 size_t copied;          /* Bytes copied from user */
170 
171                 offset = (pos & (PAGE_SIZE - 1));
172                 bytes = min_t(unsigned long, PAGE_SIZE - offset,
173                                                 iov_iter_count(i));
174 again:
175                 if (bytes > length)
176                         bytes = length;
177 
178                 /*
179                  * Bring in the user page that we will copy from _first_.
180                  * Otherwise there's a nasty deadlock on copying from the
181                  * same page as we're writing to, without it being marked
182                  * up-to-date.
183                  *
184                  * Not only is this an optimisation, but it is also required
185                  * to check that the address is actually valid, when atomic
186                  * usercopies are used, below.
187                  */
188                 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
189                         status = -EFAULT;
190                         break;
191                 }
192 
193                 status = iomap_write_begin(inode, pos, bytes, flags, &page,
194                                 iomap);
195                 if (unlikely(status))
196                         break;
197 
198                 if (mapping_writably_mapped(inode->i_mapping))
199                         flush_dcache_page(page);
200 
201                 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
202 
203                 flush_dcache_page(page);
204 
205                 status = iomap_write_end(inode, pos, bytes, copied, page);
206                 if (unlikely(status < 0))
207                         break;
208                 copied = status;
209 
210                 cond_resched();
211 
212                 iov_iter_advance(i, copied);
213                 if (unlikely(copied == 0)) {
214                         /*
215                          * If we were unable to copy any data at all, we must
216                          * fall back to a single segment length write.
217                          *
218                          * If we didn't fallback here, we could livelock
219                          * because not all segments in the iov can be copied at
220                          * once without a pagefault.
221                          */
222                         bytes = min_t(unsigned long, PAGE_SIZE - offset,
223                                                 iov_iter_single_seg_count(i));
224                         goto again;
225                 }
226                 pos += copied;
227                 written += copied;
228                 length -= copied;
229 
230                 balance_dirty_pages_ratelimited(inode->i_mapping);
231         } while (iov_iter_count(i) && length);
232 
233         return written ? written : status;
234 }
235 
236 ssize_t
237 iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
238                 struct iomap_ops *ops)
239 {
240         struct inode *inode = iocb->ki_filp->f_mapping->host;
241         loff_t pos = iocb->ki_pos, ret = 0, written = 0;
242 
243         while (iov_iter_count(iter)) {
244                 ret = iomap_apply(inode, pos, iov_iter_count(iter),
245                                 IOMAP_WRITE, ops, iter, iomap_write_actor);
246                 if (ret <= 0)
247                         break;
248                 pos += ret;
249                 written += ret;
250         }
251 
252         return written ? written : ret;
253 }
254 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
255 
256 static struct page *
257 __iomap_read_page(struct inode *inode, loff_t offset)
258 {
259         struct address_space *mapping = inode->i_mapping;
260         struct page *page;
261 
262         page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
263         if (IS_ERR(page))
264                 return page;
265         if (!PageUptodate(page)) {
266                 put_page(page);
267                 return ERR_PTR(-EIO);
268         }
269         return page;
270 }
271 
272 static loff_t
273 iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
274                 struct iomap *iomap)
275 {
276         long status = 0;
277         ssize_t written = 0;
278 
279         do {
280                 struct page *page, *rpage;
281                 unsigned long offset;   /* Offset into pagecache page */
282                 unsigned long bytes;    /* Bytes to write to page */
283 
284                 offset = (pos & (PAGE_SIZE - 1));
285                 bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
286 
287                 rpage = __iomap_read_page(inode, pos);
288                 if (IS_ERR(rpage))
289                         return PTR_ERR(rpage);
290 
291                 status = iomap_write_begin(inode, pos, bytes,
292                                 AOP_FLAG_NOFS | AOP_FLAG_UNINTERRUPTIBLE,
293                                 &page, iomap);
294                 put_page(rpage);
295                 if (unlikely(status))
296                         return status;
297 
298                 WARN_ON_ONCE(!PageUptodate(page));
299 
300                 status = iomap_write_end(inode, pos, bytes, bytes, page);
301                 if (unlikely(status <= 0)) {
302                         if (WARN_ON_ONCE(status == 0))
303                                 return -EIO;
304                         return status;
305                 }
306 
307                 cond_resched();
308 
309                 pos += status;
310                 written += status;
311                 length -= status;
312 
313                 balance_dirty_pages_ratelimited(inode->i_mapping);
314         } while (length);
315 
316         return written;
317 }
318 
319 int
320 iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
321                 struct iomap_ops *ops)
322 {
323         loff_t ret;
324 
325         while (len) {
326                 ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
327                                 iomap_dirty_actor);
328                 if (ret <= 0)
329                         return ret;
330                 pos += ret;
331                 len -= ret;
332         }
333 
334         return 0;
335 }
336 EXPORT_SYMBOL_GPL(iomap_file_dirty);
337 
338 static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
339                 unsigned bytes, struct iomap *iomap)
340 {
341         struct page *page;
342         int status;
343 
344         status = iomap_write_begin(inode, pos, bytes,
345                         AOP_FLAG_UNINTERRUPTIBLE | AOP_FLAG_NOFS, &page, iomap);
346         if (status)
347                 return status;
348 
349         zero_user(page, offset, bytes);
350         mark_page_accessed(page);
351 
352         return iomap_write_end(inode, pos, bytes, bytes, page);
353 }
354 
355 static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
356                 struct iomap *iomap)
357 {
358         sector_t sector = iomap->blkno +
359                 (((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9);
360 
361         return __dax_zero_page_range(iomap->bdev, sector, offset, bytes);
362 }
363 
364 static loff_t
365 iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
366                 void *data, struct iomap *iomap)
367 {
368         bool *did_zero = data;
369         loff_t written = 0;
370         int status;
371 
372         /* already zeroed?  we're done. */
373         if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
374                 return count;
375 
376         do {
377                 unsigned offset, bytes;
378 
379                 offset = pos & (PAGE_SIZE - 1); /* Within page */
380                 bytes = min_t(unsigned, PAGE_SIZE - offset, count);
381 
382                 if (IS_DAX(inode))
383                         status = iomap_dax_zero(pos, offset, bytes, iomap);
384                 else
385                         status = iomap_zero(inode, pos, offset, bytes, iomap);
386                 if (status < 0)
387                         return status;
388 
389                 pos += bytes;
390                 count -= bytes;
391                 written += bytes;
392                 if (did_zero)
393                         *did_zero = true;
394         } while (count > 0);
395 
396         return written;
397 }
398 
399 int
400 iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
401                 struct iomap_ops *ops)
402 {
403         loff_t ret;
404 
405         while (len > 0) {
406                 ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
407                                 ops, did_zero, iomap_zero_range_actor);
408                 if (ret <= 0)
409                         return ret;
410 
411                 pos += ret;
412                 len -= ret;
413         }
414 
415         return 0;
416 }
417 EXPORT_SYMBOL_GPL(iomap_zero_range);
418 
419 int
420 iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
421                 struct iomap_ops *ops)
422 {
423         unsigned blocksize = (1 << inode->i_blkbits);
424         unsigned off = pos & (blocksize - 1);
425 
426         /* Block boundary? Nothing to do */
427         if (!off)
428                 return 0;
429         return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
430 }
431 EXPORT_SYMBOL_GPL(iomap_truncate_page);
432 
433 static loff_t
434 iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
435                 void *data, struct iomap *iomap)
436 {
437         struct page *page = data;
438         int ret;
439 
440         ret = __block_write_begin_int(page, pos, length, NULL, iomap);
441         if (ret)
442                 return ret;
443 
444         block_commit_write(page, 0, length);
445         return length;
446 }
447 
448 int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
449                 struct iomap_ops *ops)
450 {
451         struct page *page = vmf->page;
452         struct inode *inode = file_inode(vma->vm_file);
453         unsigned long length;
454         loff_t offset, size;
455         ssize_t ret;
456 
457         lock_page(page);
458         size = i_size_read(inode);
459         if ((page->mapping != inode->i_mapping) ||
460             (page_offset(page) > size)) {
461                 /* We overload EFAULT to mean page got truncated */
462                 ret = -EFAULT;
463                 goto out_unlock;
464         }
465 
466         /* page is wholly or partially inside EOF */
467         if (((page->index + 1) << PAGE_SHIFT) > size)
468                 length = size & ~PAGE_MASK;
469         else
470                 length = PAGE_SIZE;
471 
472         offset = page_offset(page);
473         while (length > 0) {
474                 ret = iomap_apply(inode, offset, length,
475                                 IOMAP_WRITE | IOMAP_FAULT, ops, page,
476                                 iomap_page_mkwrite_actor);
477                 if (unlikely(ret <= 0))
478                         goto out_unlock;
479                 offset += ret;
480                 length -= ret;
481         }
482 
483         set_page_dirty(page);
484         wait_for_stable_page(page);
485         return 0;
486 out_unlock:
487         unlock_page(page);
488         return ret;
489 }
490 EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
491 
492 struct fiemap_ctx {
493         struct fiemap_extent_info *fi;
494         struct iomap prev;
495 };
496 
497 static int iomap_to_fiemap(struct fiemap_extent_info *fi,
498                 struct iomap *iomap, u32 flags)
499 {
500         switch (iomap->type) {
501         case IOMAP_HOLE:
502                 /* skip holes */
503                 return 0;
504         case IOMAP_DELALLOC:
505                 flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN;
506                 break;
507         case IOMAP_UNWRITTEN:
508                 flags |= FIEMAP_EXTENT_UNWRITTEN;
509                 break;
510         case IOMAP_MAPPED:
511                 break;
512         }
513 
514         if (iomap->flags & IOMAP_F_MERGED)
515                 flags |= FIEMAP_EXTENT_MERGED;
516         if (iomap->flags & IOMAP_F_SHARED)
517                 flags |= FIEMAP_EXTENT_SHARED;
518 
519         return fiemap_fill_next_extent(fi, iomap->offset,
520                         iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
521                         iomap->length, flags);
522 
523 }
524 
525 static loff_t
526 iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
527                 struct iomap *iomap)
528 {
529         struct fiemap_ctx *ctx = data;
530         loff_t ret = length;
531 
532         if (iomap->type == IOMAP_HOLE)
533                 return length;
534 
535         ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0);
536         ctx->prev = *iomap;
537         switch (ret) {
538         case 0:         /* success */
539                 return length;
540         case 1:         /* extent array full */
541                 return 0;
542         default:
543                 return ret;
544         }
545 }
546 
547 int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
548                 loff_t start, loff_t len, struct iomap_ops *ops)
549 {
550         struct fiemap_ctx ctx;
551         loff_t ret;
552 
553         memset(&ctx, 0, sizeof(ctx));
554         ctx.fi = fi;
555         ctx.prev.type = IOMAP_HOLE;
556 
557         ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC);
558         if (ret)
559                 return ret;
560 
561         if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
562                 ret = filemap_write_and_wait(inode->i_mapping);
563                 if (ret)
564                         return ret;
565         }
566 
567         while (len > 0) {
568                 ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
569                                 iomap_fiemap_actor);
570                 /* inode with no (attribute) mapping will give ENOENT */
571                 if (ret == -ENOENT)
572                         break;
573                 if (ret < 0)
574                         return ret;
575                 if (ret == 0)
576                         break;
577 
578                 start += ret;
579                 len -= ret;
580         }
581 
582         if (ctx.prev.type != IOMAP_HOLE) {
583                 ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST);
584                 if (ret < 0)
585                         return ret;
586         }
587 
588         return 0;
589 }
590 EXPORT_SYMBOL_GPL(iomap_fiemap);
591 
592 /*
593  * Private flags for iomap_dio, must not overlap with the public ones in
594  * iomap.h:
595  */
596 #define IOMAP_DIO_WRITE         (1 << 30)
597 #define IOMAP_DIO_DIRTY         (1 << 31)
598 
599 struct iomap_dio {
600         struct kiocb            *iocb;
601         iomap_dio_end_io_t      *end_io;
602         loff_t                  i_size;
603         loff_t                  size;
604         atomic_t                ref;
605         unsigned                flags;
606         int                     error;
607 
608         union {
609                 /* used during submission and for synchronous completion: */
610                 struct {
611                         struct iov_iter         *iter;
612                         struct task_struct      *waiter;
613                         struct request_queue    *last_queue;
614                         blk_qc_t                cookie;
615                 } submit;
616 
617                 /* used for aio completion: */
618                 struct {
619                         struct work_struct      work;
620                 } aio;
621         };
622 };
623 
624 static ssize_t iomap_dio_complete(struct iomap_dio *dio)
625 {
626         struct kiocb *iocb = dio->iocb;
627         ssize_t ret;
628 
629         if (dio->end_io) {
630                 ret = dio->end_io(iocb,
631                                 dio->error ? dio->error : dio->size,
632                                 dio->flags);
633         } else {
634                 ret = dio->error;
635         }
636 
637         if (likely(!ret)) {
638                 ret = dio->size;
639                 /* check for short read */
640                 if (iocb->ki_pos + ret > dio->i_size &&
641                     !(dio->flags & IOMAP_DIO_WRITE))
642                         ret = dio->i_size - iocb->ki_pos;
643                 iocb->ki_pos += ret;
644         }
645 
646         inode_dio_end(file_inode(iocb->ki_filp));
647         kfree(dio);
648 
649         return ret;
650 }
651 
652 static void iomap_dio_complete_work(struct work_struct *work)
653 {
654         struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
655         struct kiocb *iocb = dio->iocb;
656         bool is_write = (dio->flags & IOMAP_DIO_WRITE);
657         ssize_t ret;
658 
659         ret = iomap_dio_complete(dio);
660         if (is_write && ret > 0)
661                 ret = generic_write_sync(iocb, ret);
662         iocb->ki_complete(iocb, ret, 0);
663 }
664 
665 /*
666  * Set an error in the dio if none is set yet.  We have to use cmpxchg
667  * as the submission context and the completion context(s) can race to
668  * update the error.
669  */
670 static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
671 {
672         cmpxchg(&dio->error, 0, ret);
673 }
674 
675 static void iomap_dio_bio_end_io(struct bio *bio)
676 {
677         struct iomap_dio *dio = bio->bi_private;
678         bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
679 
680         if (bio->bi_error)
681                 iomap_dio_set_error(dio, bio->bi_error);
682 
683         if (atomic_dec_and_test(&dio->ref)) {
684                 if (is_sync_kiocb(dio->iocb)) {
685                         struct task_struct *waiter = dio->submit.waiter;
686 
687                         WRITE_ONCE(dio->submit.waiter, NULL);
688                         wake_up_process(waiter);
689                 } else if (dio->flags & IOMAP_DIO_WRITE) {
690                         struct inode *inode = file_inode(dio->iocb->ki_filp);
691 
692                         INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
693                         queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
694                 } else {
695                         iomap_dio_complete_work(&dio->aio.work);
696                 }
697         }
698 
699         if (should_dirty) {
700                 bio_check_pages_dirty(bio);
701         } else {
702                 struct bio_vec *bvec;
703                 int i;
704 
705                 bio_for_each_segment_all(bvec, bio, i)
706                         put_page(bvec->bv_page);
707                 bio_put(bio);
708         }
709 }
710 
711 static blk_qc_t
712 iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
713                 unsigned len)
714 {
715         struct page *page = ZERO_PAGE(0);
716         struct bio *bio;
717 
718         bio = bio_alloc(GFP_KERNEL, 1);
719         bio->bi_bdev = iomap->bdev;
720         bio->bi_iter.bi_sector =
721                 iomap->blkno + ((pos - iomap->offset) >> 9);
722         bio->bi_private = dio;
723         bio->bi_end_io = iomap_dio_bio_end_io;
724 
725         get_page(page);
726         if (bio_add_page(bio, page, len, 0) != len)
727                 BUG();
728         bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
729 
730         atomic_inc(&dio->ref);
731         return submit_bio(bio);
732 }
733 
734 static loff_t
735 iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
736                 void *data, struct iomap *iomap)
737 {
738         struct iomap_dio *dio = data;
739         unsigned blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
740         unsigned fs_block_size = (1 << inode->i_blkbits), pad;
741         unsigned align = iov_iter_alignment(dio->submit.iter);
742         struct iov_iter iter;
743         struct bio *bio;
744         bool need_zeroout = false;
745         int nr_pages, ret;
746 
747         if ((pos | length | align) & ((1 << blkbits) - 1))
748                 return -EINVAL;
749 
750         switch (iomap->type) {
751         case IOMAP_HOLE:
752                 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
753                         return -EIO;
754                 /*FALLTHRU*/
755         case IOMAP_UNWRITTEN:
756                 if (!(dio->flags & IOMAP_DIO_WRITE)) {
757                         iov_iter_zero(length, dio->submit.iter);
758                         dio->size += length;
759                         return length;
760                 }
761                 dio->flags |= IOMAP_DIO_UNWRITTEN;
762                 need_zeroout = true;
763                 break;
764         case IOMAP_MAPPED:
765                 if (iomap->flags & IOMAP_F_SHARED)
766                         dio->flags |= IOMAP_DIO_COW;
767                 if (iomap->flags & IOMAP_F_NEW)
768                         need_zeroout = true;
769                 break;
770         default:
771                 WARN_ON_ONCE(1);
772                 return -EIO;
773         }
774 
775         /*
776          * Operate on a partial iter trimmed to the extent we were called for.
777          * We'll update the iter in the dio once we're done with this extent.
778          */
779         iter = *dio->submit.iter;
780         iov_iter_truncate(&iter, length);
781 
782         nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
783         if (nr_pages <= 0)
784                 return nr_pages;
785 
786         if (need_zeroout) {
787                 /* zero out from the start of the block to the write offset */
788                 pad = pos & (fs_block_size - 1);
789                 if (pad)
790                         iomap_dio_zero(dio, iomap, pos - pad, pad);
791         }
792 
793         do {
794                 if (dio->error)
795                         return 0;
796 
797                 bio = bio_alloc(GFP_KERNEL, nr_pages);
798                 bio->bi_bdev = iomap->bdev;
799                 bio->bi_iter.bi_sector =
800                         iomap->blkno + ((pos - iomap->offset) >> 9);
801                 bio->bi_private = dio;
802                 bio->bi_end_io = iomap_dio_bio_end_io;
803 
804                 ret = bio_iov_iter_get_pages(bio, &iter);
805                 if (unlikely(ret)) {
806                         bio_put(bio);
807                         return ret;
808                 }
809 
810                 if (dio->flags & IOMAP_DIO_WRITE) {
811                         bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
812                         task_io_account_write(bio->bi_iter.bi_size);
813                 } else {
814                         bio_set_op_attrs(bio, REQ_OP_READ, 0);
815                         if (dio->flags & IOMAP_DIO_DIRTY)
816                                 bio_set_pages_dirty(bio);
817                 }
818 
819                 dio->size += bio->bi_iter.bi_size;
820                 pos += bio->bi_iter.bi_size;
821 
822                 nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
823 
824                 atomic_inc(&dio->ref);
825 
826                 dio->submit.last_queue = bdev_get_queue(iomap->bdev);
827                 dio->submit.cookie = submit_bio(bio);
828         } while (nr_pages);
829 
830         if (need_zeroout) {
831                 /* zero out from the end of the write to the end of the block */
832                 pad = pos & (fs_block_size - 1);
833                 if (pad)
834                         iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
835         }
836 
837         iov_iter_advance(dio->submit.iter, length);
838         return length;
839 }
840 
841 ssize_t
842 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, struct iomap_ops *ops,
843                 iomap_dio_end_io_t end_io)
844 {
845         struct address_space *mapping = iocb->ki_filp->f_mapping;
846         struct inode *inode = file_inode(iocb->ki_filp);
847         size_t count = iov_iter_count(iter);
848         loff_t pos = iocb->ki_pos, end = iocb->ki_pos + count - 1, ret = 0;
849         unsigned int flags = IOMAP_DIRECT;
850         struct blk_plug plug;
851         struct iomap_dio *dio;
852 
853         lockdep_assert_held(&inode->i_rwsem);
854 
855         if (!count)
856                 return 0;
857 
858         dio = kmalloc(sizeof(*dio), GFP_KERNEL);
859         if (!dio)
860                 return -ENOMEM;
861 
862         dio->iocb = iocb;
863         atomic_set(&dio->ref, 1);
864         dio->size = 0;
865         dio->i_size = i_size_read(inode);
866         dio->end_io = end_io;
867         dio->error = 0;
868         dio->flags = 0;
869 
870         dio->submit.iter = iter;
871         if (is_sync_kiocb(iocb)) {
872                 dio->submit.waiter = current;
873                 dio->submit.cookie = BLK_QC_T_NONE;
874                 dio->submit.last_queue = NULL;
875         }
876 
877         if (iov_iter_rw(iter) == READ) {
878                 if (pos >= dio->i_size)
879                         goto out_free_dio;
880 
881                 if (iter->type == ITER_IOVEC)
882                         dio->flags |= IOMAP_DIO_DIRTY;
883         } else {
884                 dio->flags |= IOMAP_DIO_WRITE;
885                 flags |= IOMAP_WRITE;
886         }
887 
888         if (mapping->nrpages) {
889                 ret = filemap_write_and_wait_range(mapping, iocb->ki_pos, end);
890                 if (ret)
891                         goto out_free_dio;
892 
893                 ret = invalidate_inode_pages2_range(mapping,
894                                 iocb->ki_pos >> PAGE_SHIFT, end >> PAGE_SHIFT);
895                 WARN_ON_ONCE(ret);
896                 ret = 0;
897         }
898 
899         inode_dio_begin(inode);
900 
901         blk_start_plug(&plug);
902         do {
903                 ret = iomap_apply(inode, pos, count, flags, ops, dio,
904                                 iomap_dio_actor);
905                 if (ret <= 0) {
906                         /* magic error code to fall back to buffered I/O */
907                         if (ret == -ENOTBLK)
908                                 ret = 0;
909                         break;
910                 }
911                 pos += ret;
912         } while ((count = iov_iter_count(iter)) > 0);
913         blk_finish_plug(&plug);
914 
915         if (ret < 0)
916                 iomap_dio_set_error(dio, ret);
917 
918         if (ret >= 0 && iov_iter_rw(iter) == WRITE && !is_sync_kiocb(iocb) &&
919                         !inode->i_sb->s_dio_done_wq) {
920                 ret = sb_init_dio_done_wq(inode->i_sb);
921                 if (ret < 0)
922                         iomap_dio_set_error(dio, ret);
923         }
924 
925         if (!atomic_dec_and_test(&dio->ref)) {
926                 if (!is_sync_kiocb(iocb))
927                         return -EIOCBQUEUED;
928 
929                 for (;;) {
930                         set_current_state(TASK_UNINTERRUPTIBLE);
931                         if (!READ_ONCE(dio->submit.waiter))
932                                 break;
933 
934                         if (!(iocb->ki_flags & IOCB_HIPRI) ||
935                             !dio->submit.last_queue ||
936                             !blk_mq_poll(dio->submit.last_queue,
937                                          dio->submit.cookie))
938                                 io_schedule();
939                 }
940                 __set_current_state(TASK_RUNNING);
941         }
942 
943         /*
944          * Try again to invalidate clean pages which might have been cached by
945          * non-direct readahead, or faulted in by get_user_pages() if the source
946          * of the write was an mmap'ed region of the file we're writing.  Either
947          * one is a pretty crazy thing to do, so we don't support it 100%.  If
948          * this invalidation fails, tough, the write still worked...
949          */
950         if (iov_iter_rw(iter) == WRITE && mapping->nrpages) {
951                 ret = invalidate_inode_pages2_range(mapping,
952                                 iocb->ki_pos >> PAGE_SHIFT, end >> PAGE_SHIFT);
953                 WARN_ON_ONCE(ret);
954         }
955 
956         return iomap_dio_complete(dio);
957 
958 out_free_dio:
959         kfree(dio);
960         return ret;
961 }
962 EXPORT_SYMBOL_GPL(iomap_dio_rw);
963 

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