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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 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}
1/*
2 * linux/fs/nfs/direct.c
3 *
4 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
5 *
6 * High-performance uncached I/O for the Linux NFS client
7 *
8 * There are important applications whose performance or correctness
9 * depends on uncached access to file data. Database clusters
10 * (multiple copies of the same instance running on separate hosts)
11 * implement their own cache coherency protocol that subsumes file
12 * system cache protocols. Applications that process datasets
13 * considerably larger than the client's memory do not always benefit
14 * from a local cache. A streaming video server, for instance, has no
15 * need to cache the contents of a file.
16 *
17 * When an application requests uncached I/O, all read and write requests
18 * are made directly to the server; data stored or fetched via these
19 * requests is not cached in the Linux page cache. The client does not
20 * correct unaligned requests from applications. All requested bytes are
21 * held on permanent storage before a direct write system call returns to
22 * an application.
23 *
24 * Solaris implements an uncached I/O facility called directio() that
25 * is used for backups and sequential I/O to very large files. Solaris
26 * also supports uncaching whole NFS partitions with "-o forcedirectio,"
27 * an undocumented mount option.
28 *
29 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
30 * help from Andrew Morton.
31 *
32 * 18 Dec 2001 Initial implementation for 2.4 --cel
33 * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy
34 * 08 Jun 2003 Port to 2.5 APIs --cel
35 * 31 Mar 2004 Handle direct I/O without VFS support --cel
36 * 15 Sep 2004 Parallel async reads --cel
37 * 04 May 2005 support O_DIRECT with aio --cel
38 *
39 */
40
41#include <linux/errno.h>
42#include <linux/sched.h>
43#include <linux/kernel.h>
44#include <linux/file.h>
45#include <linux/pagemap.h>
46#include <linux/kref.h>
47#include <linux/slab.h>
48#include <linux/task_io_accounting_ops.h>
49#include <linux/module.h>
50
51#include <linux/nfs_fs.h>
52#include <linux/nfs_page.h>
53#include <linux/sunrpc/clnt.h>
54
55#include <linux/uaccess.h>
56#include <linux/atomic.h>
57
58#include "internal.h"
59#include "iostat.h"
60#include "pnfs.h"
61
62#define NFSDBG_FACILITY NFSDBG_VFS
63
64static struct kmem_cache *nfs_direct_cachep;
65
66/*
67 * This represents a set of asynchronous requests that we're waiting on
68 */
69struct nfs_direct_mirror {
70 ssize_t count;
71};
72
73struct nfs_direct_req {
74 struct kref kref; /* release manager */
75
76 /* I/O parameters */
77 struct nfs_open_context *ctx; /* file open context info */
78 struct nfs_lock_context *l_ctx; /* Lock context info */
79 struct kiocb * iocb; /* controlling i/o request */
80 struct inode * inode; /* target file of i/o */
81
82 /* completion state */
83 atomic_t io_count; /* i/os we're waiting for */
84 spinlock_t lock; /* protect completion state */
85
86 struct nfs_direct_mirror mirrors[NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX];
87 int mirror_count;
88
89 loff_t io_start; /* Start offset for I/O */
90 ssize_t count, /* bytes actually processed */
91 max_count, /* max expected count */
92 bytes_left, /* bytes left to be sent */
93 error; /* any reported error */
94 struct completion completion; /* wait for i/o completion */
95
96 /* commit state */
97 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
98 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
99 struct work_struct work;
100 int flags;
101#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
102#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
103 struct nfs_writeverf verf; /* unstable write verifier */
104};
105
106static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
107static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
108static void nfs_direct_write_complete(struct nfs_direct_req *dreq);
109static void nfs_direct_write_schedule_work(struct work_struct *work);
110
111static inline void get_dreq(struct nfs_direct_req *dreq)
112{
113 atomic_inc(&dreq->io_count);
114}
115
116static inline int put_dreq(struct nfs_direct_req *dreq)
117{
118 return atomic_dec_and_test(&dreq->io_count);
119}
120
121static void
122nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr)
123{
124 int i;
125 ssize_t count;
126
127 WARN_ON_ONCE(dreq->count >= dreq->max_count);
128
129 if (dreq->mirror_count == 1) {
130 dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes;
131 dreq->count += hdr->good_bytes;
132 } else {
133 /* mirrored writes */
134 count = dreq->mirrors[hdr->pgio_mirror_idx].count;
135 if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) {
136 count = hdr->io_start + hdr->good_bytes - dreq->io_start;
137 dreq->mirrors[hdr->pgio_mirror_idx].count = count;
138 }
139 /* update the dreq->count by finding the minimum agreed count from all
140 * mirrors */
141 count = dreq->mirrors[0].count;
142
143 for (i = 1; i < dreq->mirror_count; i++)
144 count = min(count, dreq->mirrors[i].count);
145
146 dreq->count = count;
147 }
148}
149
150/*
151 * nfs_direct_select_verf - select the right verifier
152 * @dreq - direct request possibly spanning multiple servers
153 * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs
154 * @commit_idx - commit bucket index for the DS
155 *
156 * returns the correct verifier to use given the role of the server
157 */
158static struct nfs_writeverf *
159nfs_direct_select_verf(struct nfs_direct_req *dreq,
160 struct nfs_client *ds_clp,
161 int commit_idx)
162{
163 struct nfs_writeverf *verfp = &dreq->verf;
164
165#ifdef CONFIG_NFS_V4_1
166 /*
167 * pNFS is in use, use the DS verf except commit_through_mds is set
168 * for layout segment where nbuckets is zero.
169 */
170 if (ds_clp && dreq->ds_cinfo.nbuckets > 0) {
171 if (commit_idx >= 0 && commit_idx < dreq->ds_cinfo.nbuckets)
172 verfp = &dreq->ds_cinfo.buckets[commit_idx].direct_verf;
173 else
174 WARN_ON_ONCE(1);
175 }
176#endif
177 return verfp;
178}
179
180
181/*
182 * nfs_direct_set_hdr_verf - set the write/commit verifier
183 * @dreq - direct request possibly spanning multiple servers
184 * @hdr - pageio header to validate against previously seen verfs
185 *
186 * Set the server's (MDS or DS) "seen" verifier
187 */
188static void nfs_direct_set_hdr_verf(struct nfs_direct_req *dreq,
189 struct nfs_pgio_header *hdr)
190{
191 struct nfs_writeverf *verfp;
192
193 verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx);
194 WARN_ON_ONCE(verfp->committed >= 0);
195 memcpy(verfp, &hdr->verf, sizeof(struct nfs_writeverf));
196 WARN_ON_ONCE(verfp->committed < 0);
197}
198
199static int nfs_direct_cmp_verf(const struct nfs_writeverf *v1,
200 const struct nfs_writeverf *v2)
201{
202 return nfs_write_verifier_cmp(&v1->verifier, &v2->verifier);
203}
204
205/*
206 * nfs_direct_cmp_hdr_verf - compare verifier for pgio header
207 * @dreq - direct request possibly spanning multiple servers
208 * @hdr - pageio header to validate against previously seen verf
209 *
210 * set the server's "seen" verf if not initialized.
211 * returns result of comparison between @hdr->verf and the "seen"
212 * verf of the server used by @hdr (DS or MDS)
213 */
214static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq,
215 struct nfs_pgio_header *hdr)
216{
217 struct nfs_writeverf *verfp;
218
219 verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx);
220 if (verfp->committed < 0) {
221 nfs_direct_set_hdr_verf(dreq, hdr);
222 return 0;
223 }
224 return nfs_direct_cmp_verf(verfp, &hdr->verf);
225}
226
227/*
228 * nfs_direct_cmp_commit_data_verf - compare verifier for commit data
229 * @dreq - direct request possibly spanning multiple servers
230 * @data - commit data to validate against previously seen verf
231 *
232 * returns result of comparison between @data->verf and the verf of
233 * the server used by @data (DS or MDS)
234 */
235static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq,
236 struct nfs_commit_data *data)
237{
238 struct nfs_writeverf *verfp;
239
240 verfp = nfs_direct_select_verf(dreq, data->ds_clp,
241 data->ds_commit_index);
242
243 /* verifier not set so always fail */
244 if (verfp->committed < 0)
245 return 1;
246
247 return nfs_direct_cmp_verf(verfp, &data->verf);
248}
249
250/**
251 * nfs_direct_IO - NFS address space operation for direct I/O
252 * @iocb: target I/O control block
253 * @iter: I/O buffer
254 *
255 * The presence of this routine in the address space ops vector means
256 * the NFS client supports direct I/O. However, for most direct IO, we
257 * shunt off direct read and write requests before the VFS gets them,
258 * so this method is only ever called for swap.
259 */
260ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
261{
262 struct inode *inode = iocb->ki_filp->f_mapping->host;
263
264 /* we only support swap file calling nfs_direct_IO */
265 if (!IS_SWAPFILE(inode))
266 return 0;
267
268 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE);
269
270 if (iov_iter_rw(iter) == READ)
271 return nfs_file_direct_read(iocb, iter);
272 return nfs_file_direct_write(iocb, iter);
273}
274
275static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
276{
277 unsigned int i;
278 for (i = 0; i < npages; i++)
279 put_page(pages[i]);
280}
281
282void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
283 struct nfs_direct_req *dreq)
284{
285 cinfo->inode = dreq->inode;
286 cinfo->mds = &dreq->mds_cinfo;
287 cinfo->ds = &dreq->ds_cinfo;
288 cinfo->dreq = dreq;
289 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
290}
291
292static inline void nfs_direct_setup_mirroring(struct nfs_direct_req *dreq,
293 struct nfs_pageio_descriptor *pgio,
294 struct nfs_page *req)
295{
296 int mirror_count = 1;
297
298 if (pgio->pg_ops->pg_get_mirror_count)
299 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
300
301 dreq->mirror_count = mirror_count;
302}
303
304static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
305{
306 struct nfs_direct_req *dreq;
307
308 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
309 if (!dreq)
310 return NULL;
311
312 kref_init(&dreq->kref);
313 kref_get(&dreq->kref);
314 init_completion(&dreq->completion);
315 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
316 dreq->verf.committed = NFS_INVALID_STABLE_HOW; /* not set yet */
317 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
318 dreq->mirror_count = 1;
319 spin_lock_init(&dreq->lock);
320
321 return dreq;
322}
323
324static void nfs_direct_req_free(struct kref *kref)
325{
326 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
327
328 nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo);
329 if (dreq->l_ctx != NULL)
330 nfs_put_lock_context(dreq->l_ctx);
331 if (dreq->ctx != NULL)
332 put_nfs_open_context(dreq->ctx);
333 kmem_cache_free(nfs_direct_cachep, dreq);
334}
335
336static void nfs_direct_req_release(struct nfs_direct_req *dreq)
337{
338 kref_put(&dreq->kref, nfs_direct_req_free);
339}
340
341ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
342{
343 return dreq->bytes_left;
344}
345EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
346
347/*
348 * Collects and returns the final error value/byte-count.
349 */
350static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
351{
352 ssize_t result = -EIOCBQUEUED;
353
354 /* Async requests don't wait here */
355 if (dreq->iocb)
356 goto out;
357
358 result = wait_for_completion_killable(&dreq->completion);
359
360 if (!result) {
361 result = dreq->count;
362 WARN_ON_ONCE(dreq->count < 0);
363 }
364 if (!result)
365 result = dreq->error;
366
367out:
368 return (ssize_t) result;
369}
370
371/*
372 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
373 * the iocb is still valid here if this is a synchronous request.
374 */
375static void nfs_direct_complete(struct nfs_direct_req *dreq)
376{
377 struct inode *inode = dreq->inode;
378
379 inode_dio_end(inode);
380
381 if (dreq->iocb) {
382 long res = (long) dreq->error;
383 if (dreq->count != 0) {
384 res = (long) dreq->count;
385 WARN_ON_ONCE(dreq->count < 0);
386 }
387 dreq->iocb->ki_complete(dreq->iocb, res, 0);
388 }
389
390 complete(&dreq->completion);
391
392 nfs_direct_req_release(dreq);
393}
394
395static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
396{
397 unsigned long bytes = 0;
398 struct nfs_direct_req *dreq = hdr->dreq;
399
400 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
401 goto out_put;
402
403 spin_lock(&dreq->lock);
404 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
405 dreq->error = hdr->error;
406 else
407 nfs_direct_good_bytes(dreq, hdr);
408
409 spin_unlock(&dreq->lock);
410
411 while (!list_empty(&hdr->pages)) {
412 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
413 struct page *page = req->wb_page;
414
415 if (!PageCompound(page) && bytes < hdr->good_bytes)
416 set_page_dirty(page);
417 bytes += req->wb_bytes;
418 nfs_list_remove_request(req);
419 nfs_release_request(req);
420 }
421out_put:
422 if (put_dreq(dreq))
423 nfs_direct_complete(dreq);
424 hdr->release(hdr);
425}
426
427static void nfs_read_sync_pgio_error(struct list_head *head)
428{
429 struct nfs_page *req;
430
431 while (!list_empty(head)) {
432 req = nfs_list_entry(head->next);
433 nfs_list_remove_request(req);
434 nfs_release_request(req);
435 }
436}
437
438static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
439{
440 get_dreq(hdr->dreq);
441}
442
443static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
444 .error_cleanup = nfs_read_sync_pgio_error,
445 .init_hdr = nfs_direct_pgio_init,
446 .completion = nfs_direct_read_completion,
447};
448
449/*
450 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
451 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
452 * bail and stop sending more reads. Read length accounting is
453 * handled automatically by nfs_direct_read_result(). Otherwise, if
454 * no requests have been sent, just return an error.
455 */
456
457static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
458 struct iov_iter *iter,
459 loff_t pos)
460{
461 struct nfs_pageio_descriptor desc;
462 struct inode *inode = dreq->inode;
463 ssize_t result = -EINVAL;
464 size_t requested_bytes = 0;
465 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
466
467 nfs_pageio_init_read(&desc, dreq->inode, false,
468 &nfs_direct_read_completion_ops);
469 get_dreq(dreq);
470 desc.pg_dreq = dreq;
471 inode_dio_begin(inode);
472
473 while (iov_iter_count(iter)) {
474 struct page **pagevec;
475 size_t bytes;
476 size_t pgbase;
477 unsigned npages, i;
478
479 result = iov_iter_get_pages_alloc(iter, &pagevec,
480 rsize, &pgbase);
481 if (result < 0)
482 break;
483
484 bytes = result;
485 iov_iter_advance(iter, bytes);
486 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
487 for (i = 0; i < npages; i++) {
488 struct nfs_page *req;
489 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
490 /* XXX do we need to do the eof zeroing found in async_filler? */
491 req = nfs_create_request(dreq->ctx, pagevec[i], NULL,
492 pgbase, req_len);
493 if (IS_ERR(req)) {
494 result = PTR_ERR(req);
495 break;
496 }
497 req->wb_index = pos >> PAGE_SHIFT;
498 req->wb_offset = pos & ~PAGE_MASK;
499 if (!nfs_pageio_add_request(&desc, req)) {
500 result = desc.pg_error;
501 nfs_release_request(req);
502 break;
503 }
504 pgbase = 0;
505 bytes -= req_len;
506 requested_bytes += req_len;
507 pos += req_len;
508 dreq->bytes_left -= req_len;
509 }
510 nfs_direct_release_pages(pagevec, npages);
511 kvfree(pagevec);
512 if (result < 0)
513 break;
514 }
515
516 nfs_pageio_complete(&desc);
517
518 /*
519 * If no bytes were started, return the error, and let the
520 * generic layer handle the completion.
521 */
522 if (requested_bytes == 0) {
523 inode_dio_end(inode);
524 nfs_direct_req_release(dreq);
525 return result < 0 ? result : -EIO;
526 }
527
528 if (put_dreq(dreq))
529 nfs_direct_complete(dreq);
530 return requested_bytes;
531}
532
533/**
534 * nfs_file_direct_read - file direct read operation for NFS files
535 * @iocb: target I/O control block
536 * @iter: vector of user buffers into which to read data
537 *
538 * We use this function for direct reads instead of calling
539 * generic_file_aio_read() in order to avoid gfar's check to see if
540 * the request starts before the end of the file. For that check
541 * to work, we must generate a GETATTR before each direct read, and
542 * even then there is a window between the GETATTR and the subsequent
543 * READ where the file size could change. Our preference is simply
544 * to do all reads the application wants, and the server will take
545 * care of managing the end of file boundary.
546 *
547 * This function also eliminates unnecessarily updating the file's
548 * atime locally, as the NFS server sets the file's atime, and this
549 * client must read the updated atime from the server back into its
550 * cache.
551 */
552ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
553{
554 struct file *file = iocb->ki_filp;
555 struct address_space *mapping = file->f_mapping;
556 struct inode *inode = mapping->host;
557 struct nfs_direct_req *dreq;
558 struct nfs_lock_context *l_ctx;
559 ssize_t result = -EINVAL, requested;
560 size_t count = iov_iter_count(iter);
561 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
562
563 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
564 file, count, (long long) iocb->ki_pos);
565
566 result = 0;
567 if (!count)
568 goto out;
569
570 task_io_account_read(count);
571
572 result = -ENOMEM;
573 dreq = nfs_direct_req_alloc();
574 if (dreq == NULL)
575 goto out;
576
577 dreq->inode = inode;
578 dreq->bytes_left = dreq->max_count = count;
579 dreq->io_start = iocb->ki_pos;
580 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
581 l_ctx = nfs_get_lock_context(dreq->ctx);
582 if (IS_ERR(l_ctx)) {
583 result = PTR_ERR(l_ctx);
584 goto out_release;
585 }
586 dreq->l_ctx = l_ctx;
587 if (!is_sync_kiocb(iocb))
588 dreq->iocb = iocb;
589
590 nfs_start_io_direct(inode);
591
592 NFS_I(inode)->read_io += count;
593 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
594
595 nfs_end_io_direct(inode);
596
597 if (requested > 0) {
598 result = nfs_direct_wait(dreq);
599 if (result > 0) {
600 requested -= result;
601 iocb->ki_pos += result;
602 }
603 iov_iter_revert(iter, requested);
604 } else {
605 result = requested;
606 }
607
608out_release:
609 nfs_direct_req_release(dreq);
610out:
611 return result;
612}
613
614static void
615nfs_direct_write_scan_commit_list(struct inode *inode,
616 struct list_head *list,
617 struct nfs_commit_info *cinfo)
618{
619 mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
620#ifdef CONFIG_NFS_V4_1
621 if (cinfo->ds != NULL && cinfo->ds->nwritten != 0)
622 NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo);
623#endif
624 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
625 mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
626}
627
628static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
629{
630 struct nfs_pageio_descriptor desc;
631 struct nfs_page *req, *tmp;
632 LIST_HEAD(reqs);
633 struct nfs_commit_info cinfo;
634 LIST_HEAD(failed);
635 int i;
636
637 nfs_init_cinfo_from_dreq(&cinfo, dreq);
638 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
639
640 dreq->count = 0;
641 dreq->verf.committed = NFS_INVALID_STABLE_HOW;
642 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
643 for (i = 0; i < dreq->mirror_count; i++)
644 dreq->mirrors[i].count = 0;
645 get_dreq(dreq);
646
647 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
648 &nfs_direct_write_completion_ops);
649 desc.pg_dreq = dreq;
650
651 req = nfs_list_entry(reqs.next);
652 nfs_direct_setup_mirroring(dreq, &desc, req);
653 if (desc.pg_error < 0) {
654 list_splice_init(&reqs, &failed);
655 goto out_failed;
656 }
657
658 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
659 if (!nfs_pageio_add_request(&desc, req)) {
660 nfs_list_remove_request(req);
661 nfs_list_add_request(req, &failed);
662 spin_lock(&cinfo.inode->i_lock);
663 dreq->flags = 0;
664 if (desc.pg_error < 0)
665 dreq->error = desc.pg_error;
666 else
667 dreq->error = -EIO;
668 spin_unlock(&cinfo.inode->i_lock);
669 }
670 nfs_release_request(req);
671 }
672 nfs_pageio_complete(&desc);
673
674out_failed:
675 while (!list_empty(&failed)) {
676 req = nfs_list_entry(failed.next);
677 nfs_list_remove_request(req);
678 nfs_unlock_and_release_request(req);
679 }
680
681 if (put_dreq(dreq))
682 nfs_direct_write_complete(dreq);
683}
684
685static void nfs_direct_commit_complete(struct nfs_commit_data *data)
686{
687 struct nfs_direct_req *dreq = data->dreq;
688 struct nfs_commit_info cinfo;
689 struct nfs_page *req;
690 int status = data->task.tk_status;
691
692 nfs_init_cinfo_from_dreq(&cinfo, dreq);
693 if (status < 0 || nfs_direct_cmp_commit_data_verf(dreq, data))
694 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
695
696 while (!list_empty(&data->pages)) {
697 req = nfs_list_entry(data->pages.next);
698 nfs_list_remove_request(req);
699 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
700 /* Note the rewrite will go through mds */
701 nfs_mark_request_commit(req, NULL, &cinfo, 0);
702 } else
703 nfs_release_request(req);
704 nfs_unlock_and_release_request(req);
705 }
706
707 if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
708 nfs_direct_write_complete(dreq);
709}
710
711static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
712 struct nfs_page *req)
713{
714 struct nfs_direct_req *dreq = cinfo->dreq;
715
716 spin_lock(&dreq->lock);
717 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
718 spin_unlock(&dreq->lock);
719 nfs_mark_request_commit(req, NULL, cinfo, 0);
720}
721
722static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
723 .completion = nfs_direct_commit_complete,
724 .resched_write = nfs_direct_resched_write,
725};
726
727static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
728{
729 int res;
730 struct nfs_commit_info cinfo;
731 LIST_HEAD(mds_list);
732
733 nfs_init_cinfo_from_dreq(&cinfo, dreq);
734 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
735 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
736 if (res < 0) /* res == -ENOMEM */
737 nfs_direct_write_reschedule(dreq);
738}
739
740static void nfs_direct_write_schedule_work(struct work_struct *work)
741{
742 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
743 int flags = dreq->flags;
744
745 dreq->flags = 0;
746 switch (flags) {
747 case NFS_ODIRECT_DO_COMMIT:
748 nfs_direct_commit_schedule(dreq);
749 break;
750 case NFS_ODIRECT_RESCHED_WRITES:
751 nfs_direct_write_reschedule(dreq);
752 break;
753 default:
754 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
755 nfs_direct_complete(dreq);
756 }
757}
758
759static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
760{
761 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
762}
763
764static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
765{
766 struct nfs_direct_req *dreq = hdr->dreq;
767 struct nfs_commit_info cinfo;
768 bool request_commit = false;
769 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
770
771 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
772 goto out_put;
773
774 nfs_init_cinfo_from_dreq(&cinfo, dreq);
775
776 spin_lock(&dreq->lock);
777
778 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
779 dreq->error = hdr->error;
780 if (dreq->error == 0) {
781 nfs_direct_good_bytes(dreq, hdr);
782 if (nfs_write_need_commit(hdr)) {
783 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
784 request_commit = true;
785 else if (dreq->flags == 0) {
786 nfs_direct_set_hdr_verf(dreq, hdr);
787 request_commit = true;
788 dreq->flags = NFS_ODIRECT_DO_COMMIT;
789 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
790 request_commit = true;
791 if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr))
792 dreq->flags =
793 NFS_ODIRECT_RESCHED_WRITES;
794 }
795 }
796 }
797 spin_unlock(&dreq->lock);
798
799 while (!list_empty(&hdr->pages)) {
800
801 req = nfs_list_entry(hdr->pages.next);
802 nfs_list_remove_request(req);
803 if (request_commit) {
804 kref_get(&req->wb_kref);
805 nfs_mark_request_commit(req, hdr->lseg, &cinfo,
806 hdr->ds_commit_idx);
807 }
808 nfs_unlock_and_release_request(req);
809 }
810
811out_put:
812 if (put_dreq(dreq))
813 nfs_direct_write_complete(dreq);
814 hdr->release(hdr);
815}
816
817static void nfs_write_sync_pgio_error(struct list_head *head)
818{
819 struct nfs_page *req;
820
821 while (!list_empty(head)) {
822 req = nfs_list_entry(head->next);
823 nfs_list_remove_request(req);
824 nfs_unlock_and_release_request(req);
825 }
826}
827
828static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
829{
830 struct nfs_direct_req *dreq = hdr->dreq;
831
832 spin_lock(&dreq->lock);
833 if (dreq->error == 0) {
834 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
835 /* fake unstable write to let common nfs resend pages */
836 hdr->verf.committed = NFS_UNSTABLE;
837 hdr->good_bytes = hdr->args.count;
838 }
839 spin_unlock(&dreq->lock);
840}
841
842static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
843 .error_cleanup = nfs_write_sync_pgio_error,
844 .init_hdr = nfs_direct_pgio_init,
845 .completion = nfs_direct_write_completion,
846 .reschedule_io = nfs_direct_write_reschedule_io,
847};
848
849
850/*
851 * NB: Return the value of the first error return code. Subsequent
852 * errors after the first one are ignored.
853 */
854/*
855 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
856 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
857 * bail and stop sending more writes. Write length accounting is
858 * handled automatically by nfs_direct_write_result(). Otherwise, if
859 * no requests have been sent, just return an error.
860 */
861static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
862 struct iov_iter *iter,
863 loff_t pos)
864{
865 struct nfs_pageio_descriptor desc;
866 struct inode *inode = dreq->inode;
867 ssize_t result = 0;
868 size_t requested_bytes = 0;
869 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
870
871 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false,
872 &nfs_direct_write_completion_ops);
873 desc.pg_dreq = dreq;
874 get_dreq(dreq);
875 inode_dio_begin(inode);
876
877 NFS_I(inode)->write_io += iov_iter_count(iter);
878 while (iov_iter_count(iter)) {
879 struct page **pagevec;
880 size_t bytes;
881 size_t pgbase;
882 unsigned npages, i;
883
884 result = iov_iter_get_pages_alloc(iter, &pagevec,
885 wsize, &pgbase);
886 if (result < 0)
887 break;
888
889 bytes = result;
890 iov_iter_advance(iter, bytes);
891 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
892 for (i = 0; i < npages; i++) {
893 struct nfs_page *req;
894 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
895
896 req = nfs_create_request(dreq->ctx, pagevec[i], NULL,
897 pgbase, req_len);
898 if (IS_ERR(req)) {
899 result = PTR_ERR(req);
900 break;
901 }
902
903 nfs_direct_setup_mirroring(dreq, &desc, req);
904 if (desc.pg_error < 0) {
905 nfs_free_request(req);
906 result = desc.pg_error;
907 break;
908 }
909
910 nfs_lock_request(req);
911 req->wb_index = pos >> PAGE_SHIFT;
912 req->wb_offset = pos & ~PAGE_MASK;
913 if (!nfs_pageio_add_request(&desc, req)) {
914 result = desc.pg_error;
915 nfs_unlock_and_release_request(req);
916 break;
917 }
918 pgbase = 0;
919 bytes -= req_len;
920 requested_bytes += req_len;
921 pos += req_len;
922 dreq->bytes_left -= req_len;
923 }
924 nfs_direct_release_pages(pagevec, npages);
925 kvfree(pagevec);
926 if (result < 0)
927 break;
928 }
929 nfs_pageio_complete(&desc);
930
931 /*
932 * If no bytes were started, return the error, and let the
933 * generic layer handle the completion.
934 */
935 if (requested_bytes == 0) {
936 inode_dio_end(inode);
937 nfs_direct_req_release(dreq);
938 return result < 0 ? result : -EIO;
939 }
940
941 if (put_dreq(dreq))
942 nfs_direct_write_complete(dreq);
943 return requested_bytes;
944}
945
946/**
947 * nfs_file_direct_write - file direct write operation for NFS files
948 * @iocb: target I/O control block
949 * @iter: vector of user buffers from which to write data
950 *
951 * We use this function for direct writes instead of calling
952 * generic_file_aio_write() in order to avoid taking the inode
953 * semaphore and updating the i_size. The NFS server will set
954 * the new i_size and this client must read the updated size
955 * back into its cache. We let the server do generic write
956 * parameter checking and report problems.
957 *
958 * We eliminate local atime updates, see direct read above.
959 *
960 * We avoid unnecessary page cache invalidations for normal cached
961 * readers of this file.
962 *
963 * Note that O_APPEND is not supported for NFS direct writes, as there
964 * is no atomic O_APPEND write facility in the NFS protocol.
965 */
966ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
967{
968 ssize_t result = -EINVAL, requested;
969 size_t count;
970 struct file *file = iocb->ki_filp;
971 struct address_space *mapping = file->f_mapping;
972 struct inode *inode = mapping->host;
973 struct nfs_direct_req *dreq;
974 struct nfs_lock_context *l_ctx;
975 loff_t pos, end;
976
977 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
978 file, iov_iter_count(iter), (long long) iocb->ki_pos);
979
980 result = generic_write_checks(iocb, iter);
981 if (result <= 0)
982 return result;
983 count = result;
984 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
985
986 pos = iocb->ki_pos;
987 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
988
989 task_io_account_write(count);
990
991 result = -ENOMEM;
992 dreq = nfs_direct_req_alloc();
993 if (!dreq)
994 goto out;
995
996 dreq->inode = inode;
997 dreq->bytes_left = dreq->max_count = count;
998 dreq->io_start = pos;
999 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
1000 l_ctx = nfs_get_lock_context(dreq->ctx);
1001 if (IS_ERR(l_ctx)) {
1002 result = PTR_ERR(l_ctx);
1003 goto out_release;
1004 }
1005 dreq->l_ctx = l_ctx;
1006 if (!is_sync_kiocb(iocb))
1007 dreq->iocb = iocb;
1008
1009 nfs_start_io_direct(inode);
1010
1011 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos);
1012
1013 if (mapping->nrpages) {
1014 invalidate_inode_pages2_range(mapping,
1015 pos >> PAGE_SHIFT, end);
1016 }
1017
1018 nfs_end_io_direct(inode);
1019
1020 if (requested > 0) {
1021 result = nfs_direct_wait(dreq);
1022 if (result > 0) {
1023 requested -= result;
1024 iocb->ki_pos = pos + result;
1025 /* XXX: should check the generic_write_sync retval */
1026 generic_write_sync(iocb, result);
1027 }
1028 iov_iter_revert(iter, requested);
1029 } else {
1030 result = requested;
1031 }
1032out_release:
1033 nfs_direct_req_release(dreq);
1034out:
1035 return result;
1036}
1037
1038/**
1039 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1040 *
1041 */
1042int __init nfs_init_directcache(void)
1043{
1044 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1045 sizeof(struct nfs_direct_req),
1046 0, (SLAB_RECLAIM_ACCOUNT|
1047 SLAB_MEM_SPREAD),
1048 NULL);
1049 if (nfs_direct_cachep == NULL)
1050 return -ENOMEM;
1051
1052 return 0;
1053}
1054
1055/**
1056 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1057 *
1058 */
1059void nfs_destroy_directcache(void)
1060{
1061 kmem_cache_destroy(nfs_direct_cachep);
1062}