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(v: &dreq->io_count);
77}
78
79static inline int put_dreq(struct nfs_direct_req *dreq)
80{
81 return atomic_dec_and_test(v: &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(i: iter) == READ)
147 ret = nfs_file_direct_read(iocb, iter, swap: true);
148 else
149 ret = nfs_file_direct_write(iocb, iter, swap: 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(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(k: nfs_direct_cachep, GFP_KERNEL);
177 if (!dreq)
178 return NULL;
179
180 kref_init(kref: &dreq->kref);
181 kref_get(kref: &dreq->kref);
182 init_completion(x: &dreq->completion);
183 INIT_LIST_HEAD(list: &dreq->mds_cinfo.list);
184 pnfs_init_ds_commit_info(fl_cinfo: &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(fl_cinfo: &dreq->ds_cinfo, inode: dreq->inode);
196 if (dreq->l_ctx != NULL)
197 nfs_put_lock_context(l_ctx: dreq->l_ctx);
198 if (dreq->ctx != NULL)
199 put_nfs_open_context(ctx: dreq->ctx);
200 kmem_cache_free(s: nfs_direct_cachep, objp: dreq);
201}
202
203static void nfs_direct_req_release(struct nfs_direct_req *dreq)
204{
205 kref_put(kref: &dreq->kref, release: 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(x: &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(lock: &dreq->lock);
269 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
270 spin_unlock(lock: &dreq->lock);
271 goto out_put;
272 }
273
274 nfs_direct_count_bytes(dreq, hdr);
275 spin_unlock(lock: &dreq->lock);
276
277 while (!list_empty(head: &hdr->pages)) {
278 struct nfs_page *req = nfs_list_entry(head: 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: 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(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(pgio: &desc, inode: dreq->inode, force_mds: false,
335 compl_ops: &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(i: 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(i: iter, pages: &pagevec,
347 maxsize: rsize, start: &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(ctx: dreq->ctx, page: pagevec[i],
358 pgbase, offset: pos, count: req_len);
359 if (IS_ERR(ptr: req)) {
360 result = PTR_ERR(ptr: 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(pages: pagevec, npages);
374 kvfree(addr: pagevec);
375 if (result < 0)
376 break;
377 }
378
379 nfs_pageio_complete(desc: &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(i: iter);
426 nfs_add_stats(inode: mapping->host, stat: NFSIOS_DIRECTREADBYTES, addend: 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(bytes: 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(ctx: nfs_file_open_context(filp: iocb->ki_filp));
446 l_ctx = nfs_get_lock_context(ctx: dreq->ctx);
447 if (IS_ERR(ptr: l_ctx)) {
448 result = PTR_ERR(ptr: l_ctx);
449 nfs_direct_req_release(dreq);
450 goto out_release;
451 }
452 dreq->l_ctx = l_ctx;
453 if (!is_sync_kiocb(kiocb: iocb))
454 dreq->iocb = iocb;
455
456 if (user_backed_iter(i: 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, pos: 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(i: iter, bytes: 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: &head->wb_list) || !nfs_lock_request(req: head))
491 return;
492 if (!list_empty(head: &head->wb_list)) {
493 nfs_unlock_request(req: head);
494 return;
495 }
496 list_add(new: &head->wb_list, head: list);
497 kref_get(kref: &head->wb_kref);
498 kref_get(kref: &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(list: &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(head: &subreq->wb_list)) {
521 nfs_list_remove_request(req: subreq);
522 nfs_release_request(subreq);
523 }
524 } while ((subreq = subreq->wb_this_page) != req);
525 nfs_join_page_group(head: 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(head: list, cinfo);
536 nfs_scan_commit_list(src: &cinfo->mds->list, dst: list, cinfo, max: 0);
537 mutex_unlock(lock: &NFS_I(inode: 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: &cinfo, dreq);
548 nfs_direct_write_scan_commit_list(inode: dreq->inode, list: &reqs, cinfo: &cinfo);
549
550 nfs_direct_join_group(list: &reqs, cinfo: &cinfo, inode: dreq->inode);
551
552 nfs_clear_pnfs_ds_commit_verifiers(cinfo: &dreq->ds_cinfo);
553 get_dreq(dreq);
554
555 nfs_pageio_init_write(pgio: &desc, inode: dreq->inode, FLUSH_STABLE, force_mds: false,
556 compl_ops: &nfs_direct_write_completion_ops);
557 desc.pg_dreq = dreq;
558
559 while (!list_empty(head: &reqs)) {
560 req = nfs_list_entry(head: reqs.next);
561 /* Bump the transmission count */
562 req->wb_nio++;
563 if (!nfs_pageio_add_request(&desc, req)) {
564 spin_lock(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(lock: &dreq->lock);
575 break;
576 }
577 nfs_release_request(req);
578 }
579 nfs_pageio_complete(desc: &desc);
580
581 while (!list_empty(head: &reqs)) {
582 req = nfs_list_entry(head: 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: &cinfo, ds_commit_idx: 0);
587 } else {
588 spin_lock(lock: &dreq->lock);
589 nfs_direct_truncate_request(dreq, req);
590 spin_unlock(lock: &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 spin_lock(lock: &dreq->lock);
610 if (status < 0) {
611 /* Errors in commit are fatal */
612 dreq->error = status;
613 dreq->flags = NFS_ODIRECT_DONE;
614 } else {
615 status = dreq->error;
616 }
617 spin_unlock(lock: &dreq->lock);
618
619 nfs_init_cinfo_from_dreq(cinfo: &cinfo, dreq);
620
621 while (!list_empty(head: &data->pages)) {
622 req = nfs_list_entry(head: data->pages.next);
623 nfs_list_remove_request(req);
624 if (status < 0) {
625 spin_lock(lock: &dreq->lock);
626 nfs_direct_truncate_request(dreq, req);
627 spin_unlock(lock: &dreq->lock);
628 nfs_release_request(req);
629 } else if (!nfs_write_match_verf(verf, req)) {
630 spin_lock(lock: &dreq->lock);
631 if (dreq->flags == 0)
632 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
633 spin_unlock(lock: &dreq->lock);
634 /*
635 * Despite the reboot, the write was successful,
636 * so reset wb_nio.
637 */
638 req->wb_nio = 0;
639 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 0);
640 } else
641 nfs_release_request(req);
642 nfs_unlock_and_release_request(req);
643 }
644
645 if (nfs_commit_end(cinfo: cinfo.mds))
646 nfs_direct_write_complete(dreq);
647}
648
649static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
650 struct nfs_page *req)
651{
652 struct nfs_direct_req *dreq = cinfo->dreq;
653
654 trace_nfs_direct_resched_write(dreq);
655
656 spin_lock(lock: &dreq->lock);
657 if (dreq->flags != NFS_ODIRECT_DONE)
658 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
659 spin_unlock(lock: &dreq->lock);
660 nfs_mark_request_commit(req, NULL, cinfo, ds_commit_idx: 0);
661}
662
663static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
664 .completion = nfs_direct_commit_complete,
665 .resched_write = nfs_direct_resched_write,
666};
667
668static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
669{
670 int res;
671 struct nfs_commit_info cinfo;
672 LIST_HEAD(mds_list);
673
674 nfs_init_cinfo_from_dreq(cinfo: &cinfo, dreq);
675 nfs_commit_begin(cinfo: cinfo.mds);
676 nfs_scan_commit(inode: dreq->inode, dst: &mds_list, cinfo: &cinfo);
677 res = nfs_generic_commit_list(inode: dreq->inode, head: &mds_list, how: 0, cinfo: &cinfo);
678 if (res < 0) { /* res == -ENOMEM */
679 spin_lock(lock: &dreq->lock);
680 if (dreq->flags == 0)
681 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
682 spin_unlock(lock: &dreq->lock);
683 }
684 if (nfs_commit_end(cinfo: cinfo.mds))
685 nfs_direct_write_complete(dreq);
686}
687
688static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)
689{
690 struct nfs_commit_info cinfo;
691 struct nfs_page *req;
692 LIST_HEAD(reqs);
693
694 nfs_init_cinfo_from_dreq(cinfo: &cinfo, dreq);
695 nfs_direct_write_scan_commit_list(inode: dreq->inode, list: &reqs, cinfo: &cinfo);
696
697 while (!list_empty(head: &reqs)) {
698 req = nfs_list_entry(head: reqs.next);
699 nfs_list_remove_request(req);
700 nfs_direct_truncate_request(dreq, req);
701 nfs_release_request(req);
702 nfs_unlock_and_release_request(req);
703 }
704}
705
706static void nfs_direct_write_schedule_work(struct work_struct *work)
707{
708 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
709 int flags = dreq->flags;
710
711 dreq->flags = 0;
712 switch (flags) {
713 case NFS_ODIRECT_DO_COMMIT:
714 nfs_direct_commit_schedule(dreq);
715 break;
716 case NFS_ODIRECT_RESCHED_WRITES:
717 nfs_direct_write_reschedule(dreq);
718 break;
719 default:
720 nfs_direct_write_clear_reqs(dreq);
721 nfs_zap_mapping(inode: dreq->inode, mapping: dreq->inode->i_mapping);
722 nfs_direct_complete(dreq);
723 }
724}
725
726static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
727{
728 trace_nfs_direct_write_complete(dreq);
729 queue_work(wq: nfsiod_workqueue, work: &dreq->work); /* Calls nfs_direct_write_schedule_work */
730}
731
732static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
733{
734 struct nfs_direct_req *dreq = hdr->dreq;
735 struct nfs_commit_info cinfo;
736 struct nfs_page *req = nfs_list_entry(head: hdr->pages.next);
737 int flags = NFS_ODIRECT_DONE;
738
739 trace_nfs_direct_write_completion(dreq);
740
741 nfs_init_cinfo_from_dreq(cinfo: &cinfo, dreq);
742
743 spin_lock(lock: &dreq->lock);
744 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
745 spin_unlock(lock: &dreq->lock);
746 goto out_put;
747 }
748
749 nfs_direct_count_bytes(dreq, hdr);
750 if (test_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags) &&
751 !test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
752 if (!dreq->flags)
753 dreq->flags = NFS_ODIRECT_DO_COMMIT;
754 flags = dreq->flags;
755 }
756 spin_unlock(lock: &dreq->lock);
757
758 while (!list_empty(head: &hdr->pages)) {
759
760 req = nfs_list_entry(head: hdr->pages.next);
761 nfs_list_remove_request(req);
762 if (flags == NFS_ODIRECT_DO_COMMIT) {
763 kref_get(kref: &req->wb_kref);
764 memcpy(&req->wb_verf, &hdr->verf.verifier,
765 sizeof(req->wb_verf));
766 nfs_mark_request_commit(req, lseg: hdr->lseg, cinfo: &cinfo,
767 ds_commit_idx: hdr->ds_commit_idx);
768 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
769 kref_get(kref: &req->wb_kref);
770 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 0);
771 }
772 nfs_unlock_and_release_request(req);
773 }
774
775out_put:
776 if (put_dreq(dreq))
777 nfs_direct_write_complete(dreq);
778 hdr->release(hdr);
779}
780
781static void nfs_write_sync_pgio_error(struct list_head *head, int error)
782{
783 struct nfs_page *req;
784
785 while (!list_empty(head)) {
786 req = nfs_list_entry(head: head->next);
787 nfs_list_remove_request(req);
788 nfs_unlock_and_release_request(req);
789 }
790}
791
792static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
793{
794 struct nfs_direct_req *dreq = hdr->dreq;
795 struct nfs_page *req;
796 struct nfs_commit_info cinfo;
797
798 trace_nfs_direct_write_reschedule_io(dreq);
799
800 nfs_init_cinfo_from_dreq(cinfo: &cinfo, dreq);
801 spin_lock(lock: &dreq->lock);
802 if (dreq->error == 0)
803 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
804 set_bit(nr: NFS_IOHDR_REDO, addr: &hdr->flags);
805 spin_unlock(lock: &dreq->lock);
806 while (!list_empty(head: &hdr->pages)) {
807 req = nfs_list_entry(head: hdr->pages.next);
808 nfs_list_remove_request(req);
809 nfs_unlock_request(req);
810 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 0);
811 }
812}
813
814static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
815 .error_cleanup = nfs_write_sync_pgio_error,
816 .init_hdr = nfs_direct_pgio_init,
817 .completion = nfs_direct_write_completion,
818 .reschedule_io = nfs_direct_write_reschedule_io,
819};
820
821
822/*
823 * NB: Return the value of the first error return code. Subsequent
824 * errors after the first one are ignored.
825 */
826/*
827 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
828 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
829 * bail and stop sending more writes. Write length accounting is
830 * handled automatically by nfs_direct_write_result(). Otherwise, if
831 * no requests have been sent, just return an error.
832 */
833static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
834 struct iov_iter *iter,
835 loff_t pos, int ioflags)
836{
837 struct nfs_pageio_descriptor desc;
838 struct inode *inode = dreq->inode;
839 struct nfs_commit_info cinfo;
840 ssize_t result = 0;
841 size_t requested_bytes = 0;
842 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
843 bool defer = false;
844
845 trace_nfs_direct_write_schedule_iovec(dreq);
846
847 nfs_pageio_init_write(pgio: &desc, inode, ioflags, force_mds: false,
848 compl_ops: &nfs_direct_write_completion_ops);
849 desc.pg_dreq = dreq;
850 get_dreq(dreq);
851 inode_dio_begin(inode);
852
853 NFS_I(inode)->write_io += iov_iter_count(i: iter);
854 while (iov_iter_count(i: iter)) {
855 struct page **pagevec;
856 size_t bytes;
857 size_t pgbase;
858 unsigned npages, i;
859
860 result = iov_iter_get_pages_alloc2(i: iter, pages: &pagevec,
861 maxsize: wsize, start: &pgbase);
862 if (result < 0)
863 break;
864
865 bytes = result;
866 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
867 for (i = 0; i < npages; i++) {
868 struct nfs_page *req;
869 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
870
871 req = nfs_page_create_from_page(ctx: dreq->ctx, page: pagevec[i],
872 pgbase, offset: pos, count: req_len);
873 if (IS_ERR(ptr: req)) {
874 result = PTR_ERR(ptr: req);
875 break;
876 }
877
878 if (desc.pg_error < 0) {
879 nfs_free_request(req);
880 result = desc.pg_error;
881 break;
882 }
883
884 pgbase = 0;
885 bytes -= req_len;
886 requested_bytes += req_len;
887 pos += req_len;
888
889 if (defer) {
890 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 0);
891 continue;
892 }
893
894 nfs_lock_request(req);
895 if (nfs_pageio_add_request(&desc, req))
896 continue;
897
898 /* Exit on hard errors */
899 if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) {
900 result = desc.pg_error;
901 nfs_unlock_and_release_request(req);
902 break;
903 }
904
905 /* If the error is soft, defer remaining requests */
906 nfs_init_cinfo_from_dreq(cinfo: &cinfo, dreq);
907 spin_lock(lock: &dreq->lock);
908 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
909 spin_unlock(lock: &dreq->lock);
910 nfs_unlock_request(req);
911 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 0);
912 desc.pg_error = 0;
913 defer = true;
914 }
915 nfs_direct_release_pages(pages: pagevec, npages);
916 kvfree(addr: pagevec);
917 if (result < 0)
918 break;
919 }
920 nfs_pageio_complete(desc: &desc);
921
922 /*
923 * If no bytes were started, return the error, and let the
924 * generic layer handle the completion.
925 */
926 if (requested_bytes == 0) {
927 inode_dio_end(inode);
928 nfs_direct_req_release(dreq);
929 return result < 0 ? result : -EIO;
930 }
931
932 if (put_dreq(dreq))
933 nfs_direct_write_complete(dreq);
934 return requested_bytes;
935}
936
937/**
938 * nfs_file_direct_write - file direct write operation for NFS files
939 * @iocb: target I/O control block
940 * @iter: vector of user buffers from which to write data
941 * @swap: flag indicating this is swap IO, not O_DIRECT IO
942 *
943 * We use this function for direct writes instead of calling
944 * generic_file_aio_write() in order to avoid taking the inode
945 * semaphore and updating the i_size. The NFS server will set
946 * the new i_size and this client must read the updated size
947 * back into its cache. We let the server do generic write
948 * parameter checking and report problems.
949 *
950 * We eliminate local atime updates, see direct read above.
951 *
952 * We avoid unnecessary page cache invalidations for normal cached
953 * readers of this file.
954 *
955 * Note that O_APPEND is not supported for NFS direct writes, as there
956 * is no atomic O_APPEND write facility in the NFS protocol.
957 */
958ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter,
959 bool swap)
960{
961 ssize_t result, requested;
962 size_t count;
963 struct file *file = iocb->ki_filp;
964 struct address_space *mapping = file->f_mapping;
965 struct inode *inode = mapping->host;
966 struct nfs_direct_req *dreq;
967 struct nfs_lock_context *l_ctx;
968 loff_t pos, end;
969
970 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
971 file, iov_iter_count(iter), (long long) iocb->ki_pos);
972
973 if (swap)
974 /* bypass generic checks */
975 result = iov_iter_count(i: iter);
976 else
977 result = generic_write_checks(iocb, iter);
978 if (result <= 0)
979 return result;
980 count = result;
981 nfs_add_stats(inode: mapping->host, stat: NFSIOS_DIRECTWRITTENBYTES, addend: count);
982
983 pos = iocb->ki_pos;
984 end = (pos + iov_iter_count(i: iter) - 1) >> PAGE_SHIFT;
985
986 task_io_account_write(bytes: count);
987
988 result = -ENOMEM;
989 dreq = nfs_direct_req_alloc();
990 if (!dreq)
991 goto out;
992
993 dreq->inode = inode;
994 dreq->max_count = count;
995 dreq->io_start = pos;
996 dreq->ctx = get_nfs_open_context(ctx: nfs_file_open_context(filp: iocb->ki_filp));
997 l_ctx = nfs_get_lock_context(ctx: dreq->ctx);
998 if (IS_ERR(ptr: l_ctx)) {
999 result = PTR_ERR(ptr: l_ctx);
1000 nfs_direct_req_release(dreq);
1001 goto out_release;
1002 }
1003 dreq->l_ctx = l_ctx;
1004 if (!is_sync_kiocb(kiocb: iocb))
1005 dreq->iocb = iocb;
1006 pnfs_init_ds_commit_info_ops(fl_cinfo: &dreq->ds_cinfo, inode);
1007
1008 if (swap) {
1009 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
1010 FLUSH_STABLE);
1011 } else {
1012 nfs_start_io_direct(inode);
1013
1014 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
1015 FLUSH_COND_STABLE);
1016
1017 if (mapping->nrpages) {
1018 invalidate_inode_pages2_range(mapping,
1019 start: pos >> PAGE_SHIFT, end);
1020 }
1021
1022 nfs_end_io_direct(inode);
1023 }
1024
1025 if (requested > 0) {
1026 result = nfs_direct_wait(dreq);
1027 if (result > 0) {
1028 requested -= result;
1029 iocb->ki_pos = pos + result;
1030 /* XXX: should check the generic_write_sync retval */
1031 generic_write_sync(iocb, count: result);
1032 }
1033 iov_iter_revert(i: iter, bytes: requested);
1034 } else {
1035 result = requested;
1036 }
1037 nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE);
1038out_release:
1039 nfs_direct_req_release(dreq);
1040out:
1041 return result;
1042}
1043
1044/**
1045 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1046 *
1047 */
1048int __init nfs_init_directcache(void)
1049{
1050 nfs_direct_cachep = kmem_cache_create(name: "nfs_direct_cache",
1051 size: sizeof(struct nfs_direct_req),
1052 align: 0, SLAB_RECLAIM_ACCOUNT,
1053 NULL);
1054 if (nfs_direct_cachep == NULL)
1055 return -ENOMEM;
1056
1057 return 0;
1058}
1059
1060/**
1061 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1062 *
1063 */
1064void nfs_destroy_directcache(void)
1065{
1066 kmem_cache_destroy(s: nfs_direct_cachep);
1067}
1068

source code of linux/fs/nfs/direct.c