1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/fs/nfs/direct.c
4 *
5 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
6 *
7 * High-performance uncached I/O for the Linux NFS client
8 *
9 * There are important applications whose performance or correctness
10 * depends on uncached access to file data. Database clusters
11 * (multiple copies of the same instance running on separate hosts)
12 * implement their own cache coherency protocol that subsumes file
13 * system cache protocols. Applications that process datasets
14 * considerably larger than the client's memory do not always benefit
15 * from a local cache. A streaming video server, for instance, has no
16 * need to cache the contents of a file.
17 *
18 * When an application requests uncached I/O, all read and write requests
19 * are made directly to the server; data stored or fetched via these
20 * requests is not cached in the Linux page cache. The client does not
21 * correct unaligned requests from applications. All requested bytes are
22 * held on permanent storage before a direct write system call returns to
23 * an application.
24 *
25 * Solaris implements an uncached I/O facility called directio() that
26 * is used for backups and sequential I/O to very large files. Solaris
27 * also supports uncaching whole NFS partitions with "-o forcedirectio,"
28 * an undocumented mount option.
29 *
30 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
31 * help from Andrew Morton.
32 *
33 * 18 Dec 2001 Initial implementation for 2.4 --cel
34 * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy
35 * 08 Jun 2003 Port to 2.5 APIs --cel
36 * 31 Mar 2004 Handle direct I/O without VFS support --cel
37 * 15 Sep 2004 Parallel async reads --cel
38 * 04 May 2005 support O_DIRECT with aio --cel
39 *
40 */
41
42 #include <linux/errno.h>
43 #include <linux/sched.h>
44 #include <linux/kernel.h>
45 #include <linux/file.h>
46 #include <linux/pagemap.h>
47 #include <linux/kref.h>
48 #include <linux/slab.h>
49 #include <linux/task_io_accounting_ops.h>
50 #include <linux/module.h>
51
52 #include <linux/nfs_fs.h>
53 #include <linux/nfs_page.h>
54 #include <linux/sunrpc/clnt.h>
55
56 #include <linux/uaccess.h>
57 #include <linux/atomic.h>
58
59 #include "internal.h"
60 #include "iostat.h"
61 #include "pnfs.h"
62 #include "fscache.h"
63 #include "nfstrace.h"
64
65 #define NFSDBG_FACILITY NFSDBG_VFS
66
67 static struct kmem_cache *nfs_direct_cachep;
68
69 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
70 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
71 static void nfs_direct_write_complete(struct nfs_direct_req *dreq);
72 static void nfs_direct_write_schedule_work(struct work_struct *work);
73
74 static inline void get_dreq(struct nfs_direct_req *dreq)
75 {
76 atomic_inc(&dreq->io_count);
77 }
78
79 static inline int put_dreq(struct nfs_direct_req *dreq)
80 {
81 return atomic_dec_and_test(&dreq->io_count);
82 }
83
84 static void
85 nfs_direct_handle_truncated(struct nfs_direct_req *dreq,
86 const struct nfs_pgio_header *hdr,
87 ssize_t dreq_len)
88 {
89 if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||
90 test_bit(NFS_IOHDR_EOF, &hdr->flags)))
91 return;
92 if (dreq->max_count >= dreq_len) {
93 dreq->max_count = dreq_len;
94 if (dreq->count > dreq_len)
95 dreq->count = dreq_len;
96 }
97
98 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && !dreq->error)
99 dreq->error = hdr->error;
100 }
101
102 static void
103 nfs_direct_count_bytes(struct nfs_direct_req *dreq,
104 const struct nfs_pgio_header *hdr)
105 {
106 loff_t hdr_end = hdr->io_start + hdr->good_bytes;
107 ssize_t dreq_len = 0;
108
109 if (hdr_end > dreq->io_start)
110 dreq_len = hdr_end - dreq->io_start;
111
112 nfs_direct_handle_truncated(dreq, hdr, dreq_len);
113
114 if (dreq_len > dreq->max_count)
115 dreq_len = dreq->max_count;
116
117 if (dreq->count < dreq_len)
118 dreq->count = dreq_len;
119 }
120
121 static void nfs_direct_truncate_request(struct nfs_direct_req *dreq,
122 struct nfs_page *req)
123 {
124 loff_t offs = req_offset(req);
125 size_t req_start = (size_t)(offs - dreq->io_start);
126
127 if (req_start < dreq->max_count)
128 dreq->max_count = req_start;
129 if (req_start < dreq->count)
130 dreq->count = req_start;
131 }
132
133 /**
134 * nfs_swap_rw - NFS address space operation for swap I/O
135 * @iocb: target I/O control block
136 * @iter: I/O buffer
137 *
138 * Perform IO to the swap-file. This is much like direct IO.
139 */
140 int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
141 {
142 ssize_t ret;
143
144 if (iov_iter_rw(iter) == READ)
145 ret = nfs_file_direct_read(iocb, iter, true);
146 else
147 ret = nfs_file_direct_write(iocb, iter, true);
148 if (ret < 0)
149 return ret;
150 return 0;
151 }
152
153 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
154 {
155 unsigned int i;
156 for (i = 0; i < npages; i++)
157 put_page(pages[i]);
158 }
159
160 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
161 struct nfs_direct_req *dreq)
162 {
163 cinfo->inode = dreq->inode;
164 cinfo->mds = &dreq->mds_cinfo;
165 cinfo->ds = &dreq->ds_cinfo;
166 cinfo->dreq = dreq;
167 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
168 }
169
170 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
171 {
172 struct nfs_direct_req *dreq;
173
174 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
175 if (!dreq)
176 return NULL;
177
178 kref_init(&dreq->kref);
179 kref_get(&dreq->kref);
180 init_completion(&dreq->completion);
181 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
182 pnfs_init_ds_commit_info(&dreq->ds_cinfo);
183 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
184 spin_lock_init(&dreq->lock);
185
186 return dreq;
187 }
188
189 static void nfs_direct_req_free(struct kref *kref)
190 {
191 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
192
193 pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode);
194 if (dreq->l_ctx != NULL)
195 nfs_put_lock_context(dreq->l_ctx);
196 if (dreq->ctx != NULL)
197 put_nfs_open_context(dreq->ctx);
198 kmem_cache_free(nfs_direct_cachep, dreq);
199 }
200
201 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
202 {
203 kref_put(&dreq->kref, nfs_direct_req_free);
204 }
205
206 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset)
207 {
208 loff_t start = offset - dreq->io_start;
209 return dreq->max_count - start;
210 }
211 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
212
213 /*
214 * Collects and returns the final error value/byte-count.
215 */
216 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
217 {
218 ssize_t result = -EIOCBQUEUED;
219
220 /* Async requests don't wait here */
221 if (dreq->iocb)
222 goto out;
223
224 result = wait_for_completion_killable(&dreq->completion);
225
226 if (!result) {
227 result = dreq->count;
228 WARN_ON_ONCE(dreq->count < 0);
229 }
230 if (!result)
231 result = dreq->error;
232
233 out:
234 return (ssize_t) result;
235 }
236
237 /*
238 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
239 * the iocb is still valid here if this is a synchronous request.
240 */
241 static void nfs_direct_complete(struct nfs_direct_req *dreq)
242 {
243 struct inode *inode = dreq->inode;
244
245 inode_dio_end(inode);
246
247 if (dreq->iocb) {
248 long res = (long) dreq->error;
249 if (dreq->count != 0) {
250 res = (long) dreq->count;
251 WARN_ON_ONCE(dreq->count < 0);
252 }
253 dreq->iocb->ki_complete(dreq->iocb, res);
254 }
255
256 complete(&dreq->completion);
257
258 nfs_direct_req_release(dreq);
259 }
260
261 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
262 {
263 unsigned long bytes = 0;
264 struct nfs_direct_req *dreq = hdr->dreq;
265
266 spin_lock(&dreq->lock);
267 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
268 spin_unlock(&dreq->lock);
269 goto out_put;
270 }
271
272 nfs_direct_count_bytes(dreq, hdr);
273 spin_unlock(&dreq->lock);
274
275 while (!list_empty(&hdr->pages)) {
276 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
277 struct page *page = req->wb_page;
278
279 if (!PageCompound(page) && bytes < hdr->good_bytes &&
280 (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
281 set_page_dirty(page);
282 bytes += req->wb_bytes;
283 nfs_list_remove_request(req);
284 nfs_release_request(req);
285 }
286 out_put:
287 if (put_dreq(dreq))
288 nfs_direct_complete(dreq);
289 hdr->release(hdr);
290 }
291
292 static void nfs_read_sync_pgio_error(struct list_head *head, int error)
293 {
294 struct nfs_page *req;
295
296 while (!list_empty(head)) {
297 req = nfs_list_entry(head->next);
298 nfs_list_remove_request(req);
299 nfs_release_request(req);
300 }
301 }
302
303 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
304 {
305 get_dreq(hdr->dreq);
306 }
307
308 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
309 .error_cleanup = nfs_read_sync_pgio_error,
310 .init_hdr = nfs_direct_pgio_init,
311 .completion = nfs_direct_read_completion,
312 };
313
314 /*
315 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
316 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
317 * bail and stop sending more reads. Read length accounting is
318 * handled automatically by nfs_direct_read_result(). Otherwise, if
319 * no requests have been sent, just return an error.
320 */
321
322 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
323 struct iov_iter *iter,
324 loff_t pos)
325 {
326 struct nfs_pageio_descriptor desc;
327 struct inode *inode = dreq->inode;
328 ssize_t result = -EINVAL;
329 size_t requested_bytes = 0;
330 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
331
332 nfs_pageio_init_read(&desc, dreq->inode, false,
333 &nfs_direct_read_completion_ops);
334 get_dreq(dreq);
335 desc.pg_dreq = dreq;
336 inode_dio_begin(inode);
337
338 while (iov_iter_count(iter)) {
339 struct page **pagevec;
340 size_t bytes;
341 size_t pgbase;
342 unsigned npages, i;
343
344 result = iov_iter_get_pages_alloc2(iter, &pagevec,
345 rsize, &pgbase);
346 if (result < 0)
347 break;
348
349 bytes = result;
350 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
351 for (i = 0; i < npages; i++) {
352 struct nfs_page *req;
353 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
354 /* XXX do we need to do the eof zeroing found in async_filler? */
355 req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
356 pgbase, pos, req_len);
357 if (IS_ERR(req)) {
358 result = PTR_ERR(req);
359 break;
360 }
361 if (!nfs_pageio_add_request(&desc, req)) {
362 result = desc.pg_error;
363 nfs_release_request(req);
364 break;
365 }
366 pgbase = 0;
367 bytes -= req_len;
368 requested_bytes += req_len;
369 pos += req_len;
370 }
371 nfs_direct_release_pages(pagevec, npages);
372 kvfree(pagevec);
373 if (result < 0)
374 break;
375 }
376
377 nfs_pageio_complete(&desc);
378
379 /*
380 * If no bytes were started, return the error, and let the
381 * generic layer handle the completion.
382 */
383 if (requested_bytes == 0) {
384 inode_dio_end(inode);
385 nfs_direct_req_release(dreq);
386 return result < 0 ? result : -EIO;
387 }
388
389 if (put_dreq(dreq))
390 nfs_direct_complete(dreq);
391 return requested_bytes;
392 }
393
394 /**
395 * nfs_file_direct_read - file direct read operation for NFS files
396 * @iocb: target I/O control block
397 * @iter: vector of user buffers into which to read data
398 * @swap: flag indicating this is swap IO, not O_DIRECT IO
399 *
400 * We use this function for direct reads instead of calling
401 * generic_file_aio_read() in order to avoid gfar's check to see if
402 * the request starts before the end of the file. For that check
403 * to work, we must generate a GETATTR before each direct read, and
404 * even then there is a window between the GETATTR and the subsequent
405 * READ where the file size could change. Our preference is simply
406 * to do all reads the application wants, and the server will take
407 * care of managing the end of file boundary.
408 *
409 * This function also eliminates unnecessarily updating the file's
410 * atime locally, as the NFS server sets the file's atime, and this
411 * client must read the updated atime from the server back into its
412 * cache.
413 */
414 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter,
415 bool swap)
416 {
417 struct file *file = iocb->ki_filp;
418 struct address_space *mapping = file->f_mapping;
419 struct inode *inode = mapping->host;
420 struct nfs_direct_req *dreq;
421 struct nfs_lock_context *l_ctx;
422 ssize_t result, requested;
423 size_t count = iov_iter_count(iter);
424 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
425
426 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
427 file, count, (long long) iocb->ki_pos);
428
429 result = 0;
430 if (!count)
431 goto out;
432
433 task_io_account_read(count);
434
435 result = -ENOMEM;
436 dreq = nfs_direct_req_alloc();
437 if (dreq == NULL)
438 goto out;
439
440 dreq->inode = inode;
441 dreq->max_count = count;
442 dreq->io_start = iocb->ki_pos;
443 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
444 l_ctx = nfs_get_lock_context(dreq->ctx);
445 if (IS_ERR(l_ctx)) {
446 result = PTR_ERR(l_ctx);
447 nfs_direct_req_release(dreq);
448 goto out_release;
449 }
450 dreq->l_ctx = l_ctx;
451 if (!is_sync_kiocb(iocb))
452 dreq->iocb = iocb;
453
454 if (user_backed_iter(iter))
455 dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
456
457 if (!swap)
458 nfs_start_io_direct(inode);
459
460 NFS_I(inode)->read_io += count;
461 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
462
463 if (!swap)
464 nfs_end_io_direct(inode);
465
466 if (requested > 0) {
467 result = nfs_direct_wait(dreq);
468 if (result > 0) {
469 requested -= result;
470 iocb->ki_pos += result;
471 }
472 iov_iter_revert(iter, requested);
473 } else {
474 result = requested;
475 }
476
477 out_release:
478 nfs_direct_req_release(dreq);
479 out:
480 return result;
481 }
482
483 static void nfs_direct_add_page_head(struct list_head *list,
484 struct nfs_page *req)
485 {
486 struct nfs_page *head = req->wb_head;
487
488 if (!list_empty(&head->wb_list) || !nfs_lock_request(head))
489 return;
490 if (!list_empty(&head->wb_list)) {
491 nfs_unlock_request(head);
492 return;
493 }
494 list_add(&head->wb_list, list);
495 kref_get(&head->wb_kref);
496 kref_get(&head->wb_kref);
497 }
498
499 static void nfs_direct_join_group(struct list_head *list,
500 struct nfs_commit_info *cinfo,
501 struct inode *inode)
502 {
503 struct nfs_page *req, *subreq;
504
505 list_for_each_entry(req, list, wb_list) {
506 if (req->wb_head != req) {
507 nfs_direct_add_page_head(&req->wb_list, req);
508 continue;
509 }
510 subreq = req->wb_this_page;
511 if (subreq == req)
512 continue;
513 do {
514 /*
515 * Remove subrequests from this list before freeing
516 * them in the call to nfs_join_page_group().
517 */
518 if (!list_empty(&subreq->wb_list)) {
519 nfs_list_remove_request(subreq);
520 nfs_release_request(subreq);
521 }
522 } while ((subreq = subreq->wb_this_page) != req);
523 nfs_join_page_group(req, cinfo, inode);
524 }
525 }
526
527 static void
528 nfs_direct_write_scan_commit_list(struct inode *inode,
529 struct list_head *list,
530 struct nfs_commit_info *cinfo)
531 {
532 mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
533 pnfs_recover_commit_reqs(list, cinfo);
534 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
535 mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
536 }
537
538 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
539 {
540 struct nfs_pageio_descriptor desc;
541 struct nfs_page *req;
542 LIST_HEAD(reqs);
543 struct nfs_commit_info cinfo;
544
545 nfs_init_cinfo_from_dreq(&cinfo, dreq);
546 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
547
548 nfs_direct_join_group(&reqs, &cinfo, dreq->inode);
549
550 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
551 get_dreq(dreq);
552
553 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
554 &nfs_direct_write_completion_ops);
555 desc.pg_dreq = dreq;
556
557 while (!list_empty(&reqs)) {
558 req = nfs_list_entry(reqs.next);
559 /* Bump the transmission count */
560 req->wb_nio++;
561 if (!nfs_pageio_add_request(&desc, req)) {
562 spin_lock(&dreq->lock);
563 if (dreq->error < 0) {
564 desc.pg_error = dreq->error;
565 } else if (desc.pg_error != -EAGAIN) {
566 dreq->flags = 0;
567 if (!desc.pg_error)
568 desc.pg_error = -EIO;
569 dreq->error = desc.pg_error;
570 } else
571 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
572 spin_unlock(&dreq->lock);
573 break;
574 }
575 nfs_release_request(req);
576 }
577 nfs_pageio_complete(&desc);
578
579 while (!list_empty(&reqs)) {
580 req = nfs_list_entry(reqs.next);
581 nfs_list_remove_request(req);
582 nfs_unlock_and_release_request(req);
583 if (desc.pg_error == -EAGAIN) {
584 nfs_mark_request_commit(req, NULL, &cinfo, 0);
585 } else {
586 spin_lock(&dreq->lock);
587 nfs_direct_truncate_request(dreq, req);
588 spin_unlock(&dreq->lock);
589 nfs_release_request(req);
590 }
591 }
592
593 if (put_dreq(dreq))
594 nfs_direct_write_complete(dreq);
595 }
596
597 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
598 {
599 const struct nfs_writeverf *verf = data->res.verf;
600 struct nfs_direct_req *dreq = data->dreq;
601 struct nfs_commit_info cinfo;
602 struct nfs_page *req;
603 int status = data->task.tk_status;
604
605 trace_nfs_direct_commit_complete(dreq);
606
607 spin_lock(&dreq->lock);
608 if (status < 0) {
609 /* Errors in commit are fatal */
610 dreq->error = status;
611 dreq->flags = NFS_ODIRECT_DONE;
612 } else {
613 status = dreq->error;
614 }
615 spin_unlock(&dreq->lock);
616
617 nfs_init_cinfo_from_dreq(&cinfo, dreq);
618
619 while (!list_empty(&data->pages)) {
620 req = nfs_list_entry(data->pages.next);
621 nfs_list_remove_request(req);
622 if (status < 0) {
623 spin_lock(&dreq->lock);
624 nfs_direct_truncate_request(dreq, req);
625 spin_unlock(&dreq->lock);
626 nfs_release_request(req);
627 } else if (!nfs_write_match_verf(verf, req)) {
628 spin_lock(&dreq->lock);
629 if (dreq->flags == 0)
630 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
631 spin_unlock(&dreq->lock);
632 /*
633 * Despite the reboot, the write was successful,
634 * so reset wb_nio.
635 */
636 req->wb_nio = 0;
637 nfs_mark_request_commit(req, NULL, &cinfo, 0);
638 } else
639 nfs_release_request(req);
640 nfs_unlock_and_release_request(req);
641 }
642
643 if (nfs_commit_end(cinfo.mds))
644 nfs_direct_write_complete(dreq);
645 }
646
647 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
648 struct nfs_page *req)
649 {
650 struct nfs_direct_req *dreq = cinfo->dreq;
651
652 trace_nfs_direct_resched_write(dreq);
653
654 spin_lock(&dreq->lock);
655 if (dreq->flags != NFS_ODIRECT_DONE)
656 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
657 spin_unlock(&dreq->lock);
658 nfs_mark_request_commit(req, NULL, cinfo, 0);
659 }
660
661 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
662 .completion = nfs_direct_commit_complete,
663 .resched_write = nfs_direct_resched_write,
664 };
665
666 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
667 {
668 int res;
669 struct nfs_commit_info cinfo;
670 LIST_HEAD(mds_list);
671
672 nfs_init_cinfo_from_dreq(&cinfo, dreq);
673 nfs_commit_begin(cinfo.mds);
674 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
675 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
676 if (res < 0) { /* res == -ENOMEM */
677 spin_lock(&dreq->lock);
678 if (dreq->flags == 0)
679 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
680 spin_unlock(&dreq->lock);
681 }
682 if (nfs_commit_end(cinfo.mds))
683 nfs_direct_write_complete(dreq);
684 }
685
686 static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)
687 {
688 struct nfs_commit_info cinfo;
689 struct nfs_page *req;
690 LIST_HEAD(reqs);
691
692 nfs_init_cinfo_from_dreq(&cinfo, dreq);
693 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
694
695 while (!list_empty(&reqs)) {
696 req = nfs_list_entry(reqs.next);
697 nfs_list_remove_request(req);
698 nfs_direct_truncate_request(dreq, req);
699 nfs_release_request(req);
700 nfs_unlock_and_release_request(req);
701 }
702 }
703
704 static void nfs_direct_write_schedule_work(struct work_struct *work)
705 {
706 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
707 int flags = dreq->flags;
708
709 dreq->flags = 0;
710 switch (flags) {
711 case NFS_ODIRECT_DO_COMMIT:
712 nfs_direct_commit_schedule(dreq);
713 break;
714 case NFS_ODIRECT_RESCHED_WRITES:
715 nfs_direct_write_reschedule(dreq);
716 break;
717 default:
718 nfs_direct_write_clear_reqs(dreq);
719 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
720 nfs_direct_complete(dreq);
721 }
722 }
723
724 static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
725 {
726 trace_nfs_direct_write_complete(dreq);
727 queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */
728 }
729
730 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
731 {
732 struct nfs_direct_req *dreq = hdr->dreq;
733 struct nfs_commit_info cinfo;
734 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
735 int flags = NFS_ODIRECT_DONE;
736
737 trace_nfs_direct_write_completion(dreq);
738
739 nfs_init_cinfo_from_dreq(&cinfo, dreq);
740
741 spin_lock(&dreq->lock);
742 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
743 spin_unlock(&dreq->lock);
744 goto out_put;
745 }
746
747 nfs_direct_count_bytes(dreq, hdr);
748 if (test_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags) &&
749 !test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
750 if (!dreq->flags)
751 dreq->flags = NFS_ODIRECT_DO_COMMIT;
752 flags = dreq->flags;
753 }
754 spin_unlock(&dreq->lock);
755
756 while (!list_empty(&hdr->pages)) {
757
758 req = nfs_list_entry(hdr->pages.next);
759 nfs_list_remove_request(req);
760 if (flags == NFS_ODIRECT_DO_COMMIT) {
761 kref_get(&req->wb_kref);
762 memcpy(&req->wb_verf, &hdr->verf.verifier,
763 sizeof(req->wb_verf));
764 nfs_mark_request_commit(req, hdr->lseg, &cinfo,
765 hdr->ds_commit_idx);
766 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
767 kref_get(&req->wb_kref);
768 nfs_mark_request_commit(req, NULL, &cinfo, 0);
769 }
770 nfs_unlock_and_release_request(req);
771 }
772
773 out_put:
774 if (put_dreq(dreq))
775 nfs_direct_write_complete(dreq);
776 hdr->release(hdr);
777 }
778
779 static void nfs_write_sync_pgio_error(struct list_head *head, int error)
780 {
781 struct nfs_page *req;
782
783 while (!list_empty(head)) {
784 req = nfs_list_entry(head->next);
785 nfs_list_remove_request(req);
786 nfs_unlock_and_release_request(req);
787 }
788 }
789
790 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
791 {
792 struct nfs_direct_req *dreq = hdr->dreq;
793 struct nfs_page *req;
794 struct nfs_commit_info cinfo;
795
796 trace_nfs_direct_write_reschedule_io(dreq);
797
798 nfs_init_cinfo_from_dreq(&cinfo, dreq);
799 spin_lock(&dreq->lock);
800 if (dreq->error == 0)
801 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
802 set_bit(NFS_IOHDR_REDO, &hdr->flags);
803 spin_unlock(&dreq->lock);
804 while (!list_empty(&hdr->pages)) {
805 req = nfs_list_entry(hdr->pages.next);
806 nfs_list_remove_request(req);
807 nfs_unlock_request(req);
808 nfs_mark_request_commit(req, NULL, &cinfo, 0);
809 }
810 }
811
812 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
813 .error_cleanup = nfs_write_sync_pgio_error,
814 .init_hdr = nfs_direct_pgio_init,
815 .completion = nfs_direct_write_completion,
816 .reschedule_io = nfs_direct_write_reschedule_io,
817 };
818
819
820 /*
821 * NB: Return the value of the first error return code. Subsequent
822 * errors after the first one are ignored.
823 */
824 /*
825 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
826 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
827 * bail and stop sending more writes. Write length accounting is
828 * handled automatically by nfs_direct_write_result(). Otherwise, if
829 * no requests have been sent, just return an error.
830 */
831 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
832 struct iov_iter *iter,
833 loff_t pos, int ioflags)
834 {
835 struct nfs_pageio_descriptor desc;
836 struct inode *inode = dreq->inode;
837 struct nfs_commit_info cinfo;
838 ssize_t result = 0;
839 size_t requested_bytes = 0;
840 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
841 bool defer = false;
842
843 trace_nfs_direct_write_schedule_iovec(dreq);
844
845 nfs_pageio_init_write(&desc, inode, ioflags, false,
846 &nfs_direct_write_completion_ops);
847 desc.pg_dreq = dreq;
848 get_dreq(dreq);
849 inode_dio_begin(inode);
850
851 NFS_I(inode)->write_io += iov_iter_count(iter);
852 while (iov_iter_count(iter)) {
853 struct page **pagevec;
854 size_t bytes;
855 size_t pgbase;
856 unsigned npages, i;
857
858 result = iov_iter_get_pages_alloc2(iter, &pagevec,
859 wsize, &pgbase);
860 if (result < 0)
861 break;
862
863 bytes = result;
864 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
865 for (i = 0; i < npages; i++) {
866 struct nfs_page *req;
867 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
868
869 req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
870 pgbase, pos, req_len);
871 if (IS_ERR(req)) {
872 result = PTR_ERR(req);
873 break;
874 }
875
876 if (desc.pg_error < 0) {
877 nfs_free_request(req);
878 result = desc.pg_error;
879 break;
880 }
881
882 pgbase = 0;
883 bytes -= req_len;
884 requested_bytes += req_len;
885 pos += req_len;
886
887 if (defer) {
888 nfs_mark_request_commit(req, NULL, &cinfo, 0);
889 continue;
890 }
891
892 nfs_lock_request(req);
893 if (nfs_pageio_add_request(&desc, req))
894 continue;
895
896 /* Exit on hard errors */
897 if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) {
898 result = desc.pg_error;
899 nfs_unlock_and_release_request(req);
900 break;
901 }
902
903 /* If the error is soft, defer remaining requests */
904 nfs_init_cinfo_from_dreq(&cinfo, dreq);
905 spin_lock(&dreq->lock);
906 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
907 spin_unlock(&dreq->lock);
908 nfs_unlock_request(req);
909 nfs_mark_request_commit(req, NULL, &cinfo, 0);
910 desc.pg_error = 0;
911 defer = true;
912 }
913 nfs_direct_release_pages(pagevec, npages);
914 kvfree(pagevec);
915 if (result < 0)
916 break;
917 }
918 nfs_pageio_complete(&desc);
919
920 /*
921 * If no bytes were started, return the error, and let the
922 * generic layer handle the completion.
923 */
924 if (requested_bytes == 0) {
925 inode_dio_end(inode);
926 nfs_direct_req_release(dreq);
927 return result < 0 ? result : -EIO;
928 }
929
930 if (put_dreq(dreq))
931 nfs_direct_write_complete(dreq);
932 return requested_bytes;
933 }
934
935 /**
936 * nfs_file_direct_write - file direct write operation for NFS files
937 * @iocb: target I/O control block
938 * @iter: vector of user buffers from which to write data
939 * @swap: flag indicating this is swap IO, not O_DIRECT IO
940 *
941 * We use this function for direct writes instead of calling
942 * generic_file_aio_write() in order to avoid taking the inode
943 * semaphore and updating the i_size. The NFS server will set
944 * the new i_size and this client must read the updated size
945 * back into its cache. We let the server do generic write
946 * parameter checking and report problems.
947 *
948 * We eliminate local atime updates, see direct read above.
949 *
950 * We avoid unnecessary page cache invalidations for normal cached
951 * readers of this file.
952 *
953 * Note that O_APPEND is not supported for NFS direct writes, as there
954 * is no atomic O_APPEND write facility in the NFS protocol.
955 */
956 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter,
957 bool swap)
958 {
959 ssize_t result, requested;
960 size_t count;
961 struct file *file = iocb->ki_filp;
962 struct address_space *mapping = file->f_mapping;
963 struct inode *inode = mapping->host;
964 struct nfs_direct_req *dreq;
965 struct nfs_lock_context *l_ctx;
966 loff_t pos, end;
967
968 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
969 file, iov_iter_count(iter), (long long) iocb->ki_pos);
970
971 if (swap)
972 /* bypass generic checks */
973 result = iov_iter_count(iter);
974 else
975 result = generic_write_checks(iocb, iter);
976 if (result <= 0)
977 return result;
978 count = result;
979 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
980
981 pos = iocb->ki_pos;
982 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
983
984 task_io_account_write(count);
985
986 result = -ENOMEM;
987 dreq = nfs_direct_req_alloc();
988 if (!dreq)
989 goto out;
990
991 dreq->inode = inode;
992 dreq->max_count = count;
993 dreq->io_start = pos;
994 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
995 l_ctx = nfs_get_lock_context(dreq->ctx);
996 if (IS_ERR(l_ctx)) {
997 result = PTR_ERR(l_ctx);
998 nfs_direct_req_release(dreq);
999 goto out_release;
1000 }
1001 dreq->l_ctx = l_ctx;
1002 if (!is_sync_kiocb(iocb))
1003 dreq->iocb = iocb;
1004 pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode);
1005
1006 if (swap) {
1007 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
1008 FLUSH_STABLE);
1009 } else {
1010 nfs_start_io_direct(inode);
1011
1012 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
1013 FLUSH_COND_STABLE);
1014
1015 if (mapping->nrpages) {
1016 invalidate_inode_pages2_range(mapping,
1017 pos >> PAGE_SHIFT, end);
1018 }
1019
1020 nfs_end_io_direct(inode);
1021 }
1022
1023 if (requested > 0) {
1024 result = nfs_direct_wait(dreq);
1025 if (result > 0) {
1026 requested -= result;
1027 iocb->ki_pos = pos + result;
1028 /* XXX: should check the generic_write_sync retval */
1029 generic_write_sync(iocb, result);
1030 }
1031 iov_iter_revert(iter, requested);
1032 } else {
1033 result = requested;
1034 }
1035 nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE);
1036 out_release:
1037 nfs_direct_req_release(dreq);
1038 out:
1039 return result;
1040 }
1041
1042 /**
1043 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1044 *
1045 */
1046 int __init nfs_init_directcache(void)
1047 {
1048 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1049 sizeof(struct nfs_direct_req),
1050 0, SLAB_RECLAIM_ACCOUNT,
1051 NULL);
1052 if (nfs_direct_cachep == NULL)
1053 return -ENOMEM;
1054
1055 return 0;
1056 }
1057
1058 /**
1059 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1060 *
1061 */
1062 void nfs_destroy_directcache(void)
1063 {
1064 kmem_cache_destroy(nfs_direct_cachep);
1065 }
1066
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