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