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)
209{
210 return dreq->bytes_left;
211}
212EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
213
214/*
215 * Collects and returns the final error value/byte-count.
216 */
217static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
218{
219 ssize_t result = -EIOCBQUEUED;
220
221 /* Async requests don't wait here */
222 if (dreq->iocb)
223 goto out;
224
225 result = wait_for_completion_killable(x: &dreq->completion);
226
227 if (!result) {
228 result = dreq->count;
229 WARN_ON_ONCE(dreq->count < 0);
230 }
231 if (!result)
232 result = dreq->error;
233
234out:
235 return (ssize_t) result;
236}
237
238/*
239 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
240 * the iocb is still valid here if this is a synchronous request.
241 */
242static void nfs_direct_complete(struct nfs_direct_req *dreq)
243{
244 struct inode *inode = dreq->inode;
245
246 inode_dio_end(inode);
247
248 if (dreq->iocb) {
249 long res = (long) dreq->error;
250 if (dreq->count != 0) {
251 res = (long) dreq->count;
252 WARN_ON_ONCE(dreq->count < 0);
253 }
254 dreq->iocb->ki_complete(dreq->iocb, res);
255 }
256
257 complete(&dreq->completion);
258
259 nfs_direct_req_release(dreq);
260}
261
262static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
263{
264 unsigned long bytes = 0;
265 struct nfs_direct_req *dreq = hdr->dreq;
266
267 spin_lock(lock: &dreq->lock);
268 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
269 spin_unlock(lock: &dreq->lock);
270 goto out_put;
271 }
272
273 nfs_direct_count_bytes(dreq, hdr);
274 spin_unlock(lock: &dreq->lock);
275
276 while (!list_empty(head: &hdr->pages)) {
277 struct nfs_page *req = nfs_list_entry(head: hdr->pages.next);
278 struct page *page = req->wb_page;
279
280 if (!PageCompound(page) && bytes < hdr->good_bytes &&
281 (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
282 set_page_dirty(page);
283 bytes += req->wb_bytes;
284 nfs_list_remove_request(req);
285 nfs_release_request(req);
286 }
287out_put:
288 if (put_dreq(dreq))
289 nfs_direct_complete(dreq);
290 hdr->release(hdr);
291}
292
293static void nfs_read_sync_pgio_error(struct list_head *head, int error)
294{
295 struct nfs_page *req;
296
297 while (!list_empty(head)) {
298 req = nfs_list_entry(head: head->next);
299 nfs_list_remove_request(req);
300 nfs_release_request(req);
301 }
302}
303
304static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
305{
306 get_dreq(dreq: hdr->dreq);
307}
308
309static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
310 .error_cleanup = nfs_read_sync_pgio_error,
311 .init_hdr = nfs_direct_pgio_init,
312 .completion = nfs_direct_read_completion,
313};
314
315/*
316 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
317 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
318 * bail and stop sending more reads. Read length accounting is
319 * handled automatically by nfs_direct_read_result(). Otherwise, if
320 * no requests have been sent, just return an error.
321 */
322
323static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
324 struct iov_iter *iter,
325 loff_t pos)
326{
327 struct nfs_pageio_descriptor desc;
328 struct inode *inode = dreq->inode;
329 ssize_t result = -EINVAL;
330 size_t requested_bytes = 0;
331 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
332
333 nfs_pageio_init_read(pgio: &desc, inode: dreq->inode, force_mds: false,
334 compl_ops: &nfs_direct_read_completion_ops);
335 get_dreq(dreq);
336 desc.pg_dreq = dreq;
337 inode_dio_begin(inode);
338
339 while (iov_iter_count(i: iter)) {
340 struct page **pagevec;
341 size_t bytes;
342 size_t pgbase;
343 unsigned npages, i;
344
345 result = iov_iter_get_pages_alloc2(i: iter, pages: &pagevec,
346 maxsize: rsize, start: &pgbase);
347 if (result < 0)
348 break;
349
350 bytes = result;
351 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
352 for (i = 0; i < npages; i++) {
353 struct nfs_page *req;
354 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
355 /* XXX do we need to do the eof zeroing found in async_filler? */
356 req = nfs_page_create_from_page(ctx: dreq->ctx, page: pagevec[i],
357 pgbase, offset: pos, count: req_len);
358 if (IS_ERR(ptr: req)) {
359 result = PTR_ERR(ptr: req);
360 break;
361 }
362 if (!nfs_pageio_add_request(&desc, req)) {
363 result = desc.pg_error;
364 nfs_release_request(req);
365 break;
366 }
367 pgbase = 0;
368 bytes -= req_len;
369 requested_bytes += req_len;
370 pos += req_len;
371 dreq->bytes_left -= 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->bytes_left = 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 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: &cinfo, dreq);
618
619 while (!list_empty(head: &data->pages)) {
620 req = nfs_list_entry(head: data->pages.next);
621 nfs_list_remove_request(req);
622 if (status < 0) {
623 spin_lock(lock: &dreq->lock);
624 nfs_direct_truncate_request(dreq, req);
625 spin_unlock(lock: &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: &cinfo, ds_commit_idx: 0);
635 } else
636 nfs_release_request(req);
637 nfs_unlock_and_release_request(req);
638 }
639
640 if (nfs_commit_end(cinfo: 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(lock: &dreq->lock);
652 if (dreq->flags != NFS_ODIRECT_DONE)
653 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
654 spin_unlock(lock: &dreq->lock);
655 nfs_mark_request_commit(req, NULL, cinfo, ds_commit_idx: 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: &cinfo, dreq);
670 nfs_scan_commit(inode: dreq->inode, dst: &mds_list, cinfo: &cinfo);
671 res = nfs_generic_commit_list(inode: dreq->inode, head: &mds_list, how: 0, cinfo: &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: &cinfo, dreq);
683 nfs_direct_write_scan_commit_list(inode: dreq->inode, list: &reqs, cinfo: &cinfo);
684
685 while (!list_empty(head: &reqs)) {
686 req = nfs_list_entry(head: 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(inode: dreq->inode, mapping: 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(wq: nfsiod_workqueue, work: &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(head: 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: &cinfo, dreq);
730
731 spin_lock(lock: &dreq->lock);
732 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
733 spin_unlock(lock: &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(lock: &dreq->lock);
745
746 while (!list_empty(head: &hdr->pages)) {
747
748 req = nfs_list_entry(head: hdr->pages.next);
749 nfs_list_remove_request(req);
750 if (flags == NFS_ODIRECT_DO_COMMIT) {
751 kref_get(kref: &req->wb_kref);
752 memcpy(&req->wb_verf, &hdr->verf.verifier,
753 sizeof(req->wb_verf));
754 nfs_mark_request_commit(req, lseg: hdr->lseg, cinfo: &cinfo,
755 ds_commit_idx: hdr->ds_commit_idx);
756 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
757 kref_get(kref: &req->wb_kref);
758 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 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: 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: &cinfo, dreq);
789 spin_lock(lock: &dreq->lock);
790 if (dreq->error == 0)
791 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
792 set_bit(nr: NFS_IOHDR_REDO, addr: &hdr->flags);
793 spin_unlock(lock: &dreq->lock);
794 while (!list_empty(head: &hdr->pages)) {
795 req = nfs_list_entry(head: hdr->pages.next);
796 nfs_list_remove_request(req);
797 nfs_unlock_request(req);
798 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 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(pgio: &desc, inode, ioflags, force_mds: false,
836 compl_ops: &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(i: iter);
842 while (iov_iter_count(i: 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(i: iter, pages: &pagevec,
849 maxsize: wsize, start: &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(ctx: dreq->ctx, page: pagevec[i],
860 pgbase, offset: pos, count: req_len);
861 if (IS_ERR(ptr: req)) {
862 result = PTR_ERR(ptr: 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 dreq->bytes_left -= req_len;
877
878 if (defer) {
879 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 0);
880 continue;
881 }
882
883 nfs_lock_request(req);
884 if (nfs_pageio_add_request(&desc, req))
885 continue;
886
887 /* Exit on hard errors */
888 if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) {
889 result = desc.pg_error;
890 nfs_unlock_and_release_request(req);
891 break;
892 }
893
894 /* If the error is soft, defer remaining requests */
895 nfs_init_cinfo_from_dreq(cinfo: &cinfo, dreq);
896 spin_lock(lock: &dreq->lock);
897 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
898 spin_unlock(lock: &dreq->lock);
899 nfs_unlock_request(req);
900 nfs_mark_request_commit(req, NULL, cinfo: &cinfo, ds_commit_idx: 0);
901 desc.pg_error = 0;
902 defer = true;
903 }
904 nfs_direct_release_pages(pages: pagevec, npages);
905 kvfree(addr: pagevec);
906 if (result < 0)
907 break;
908 }
909 nfs_pageio_complete(desc: &desc);
910
911 /*
912 * If no bytes were started, return the error, and let the
913 * generic layer handle the completion.
914 */
915 if (requested_bytes == 0) {
916 inode_dio_end(inode);
917 nfs_direct_req_release(dreq);
918 return result < 0 ? result : -EIO;
919 }
920
921 if (put_dreq(dreq))
922 nfs_direct_write_complete(dreq);
923 return requested_bytes;
924}
925
926/**
927 * nfs_file_direct_write - file direct write operation for NFS files
928 * @iocb: target I/O control block
929 * @iter: vector of user buffers from which to write data
930 * @swap: flag indicating this is swap IO, not O_DIRECT IO
931 *
932 * We use this function for direct writes instead of calling
933 * generic_file_aio_write() in order to avoid taking the inode
934 * semaphore and updating the i_size. The NFS server will set
935 * the new i_size and this client must read the updated size
936 * back into its cache. We let the server do generic write
937 * parameter checking and report problems.
938 *
939 * We eliminate local atime updates, see direct read above.
940 *
941 * We avoid unnecessary page cache invalidations for normal cached
942 * readers of this file.
943 *
944 * Note that O_APPEND is not supported for NFS direct writes, as there
945 * is no atomic O_APPEND write facility in the NFS protocol.
946 */
947ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter,
948 bool swap)
949{
950 ssize_t result, requested;
951 size_t count;
952 struct file *file = iocb->ki_filp;
953 struct address_space *mapping = file->f_mapping;
954 struct inode *inode = mapping->host;
955 struct nfs_direct_req *dreq;
956 struct nfs_lock_context *l_ctx;
957 loff_t pos, end;
958
959 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
960 file, iov_iter_count(iter), (long long) iocb->ki_pos);
961
962 if (swap)
963 /* bypass generic checks */
964 result = iov_iter_count(i: iter);
965 else
966 result = generic_write_checks(iocb, iter);
967 if (result <= 0)
968 return result;
969 count = result;
970 nfs_add_stats(inode: mapping->host, stat: NFSIOS_DIRECTWRITTENBYTES, addend: count);
971
972 pos = iocb->ki_pos;
973 end = (pos + iov_iter_count(i: iter) - 1) >> PAGE_SHIFT;
974
975 task_io_account_write(bytes: count);
976
977 result = -ENOMEM;
978 dreq = nfs_direct_req_alloc();
979 if (!dreq)
980 goto out;
981
982 dreq->inode = inode;
983 dreq->bytes_left = dreq->max_count = count;
984 dreq->io_start = pos;
985 dreq->ctx = get_nfs_open_context(ctx: nfs_file_open_context(filp: iocb->ki_filp));
986 l_ctx = nfs_get_lock_context(ctx: dreq->ctx);
987 if (IS_ERR(ptr: l_ctx)) {
988 result = PTR_ERR(ptr: l_ctx);
989 nfs_direct_req_release(dreq);
990 goto out_release;
991 }
992 dreq->l_ctx = l_ctx;
993 if (!is_sync_kiocb(kiocb: iocb))
994 dreq->iocb = iocb;
995 pnfs_init_ds_commit_info_ops(fl_cinfo: &dreq->ds_cinfo, inode);
996
997 if (swap) {
998 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
999 FLUSH_STABLE);
1000 } else {
1001 nfs_start_io_direct(inode);
1002
1003 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
1004 FLUSH_COND_STABLE);
1005
1006 if (mapping->nrpages) {
1007 invalidate_inode_pages2_range(mapping,
1008 start: pos >> PAGE_SHIFT, end);
1009 }
1010
1011 nfs_end_io_direct(inode);
1012 }
1013
1014 if (requested > 0) {
1015 result = nfs_direct_wait(dreq);
1016 if (result > 0) {
1017 requested -= result;
1018 iocb->ki_pos = pos + result;
1019 /* XXX: should check the generic_write_sync retval */
1020 generic_write_sync(iocb, count: result);
1021 }
1022 iov_iter_revert(i: iter, bytes: requested);
1023 } else {
1024 result = requested;
1025 }
1026 nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE);
1027out_release:
1028 nfs_direct_req_release(dreq);
1029out:
1030 return result;
1031}
1032
1033/**
1034 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1035 *
1036 */
1037int __init nfs_init_directcache(void)
1038{
1039 nfs_direct_cachep = kmem_cache_create(name: "nfs_direct_cache",
1040 size: sizeof(struct nfs_direct_req),
1041 align: 0, flags: (SLAB_RECLAIM_ACCOUNT|
1042 SLAB_MEM_SPREAD),
1043 NULL);
1044 if (nfs_direct_cachep == NULL)
1045 return -ENOMEM;
1046
1047 return 0;
1048}
1049
1050/**
1051 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1052 *
1053 */
1054void nfs_destroy_directcache(void)
1055{
1056 kmem_cache_destroy(s: nfs_direct_cachep);
1057}
1058

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