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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
50#include <linux/nfs_fs.h>
51#include <linux/nfs_page.h>
52#include <linux/sunrpc/clnt.h>
53
54#include <asm/system.h>
55#include <asm/uaccess.h>
56#include <linux/atomic.h>
57
58#include "internal.h"
59#include "iostat.h"
60
61#define NFSDBG_FACILITY NFSDBG_VFS
62
63static struct kmem_cache *nfs_direct_cachep;
64
65/*
66 * This represents a set of asynchronous requests that we're waiting on
67 */
68struct nfs_direct_req {
69 struct kref kref; /* release manager */
70
71 /* I/O parameters */
72 struct nfs_open_context *ctx; /* file open context info */
73 struct nfs_lock_context *l_ctx; /* Lock context info */
74 struct kiocb * iocb; /* controlling i/o request */
75 struct inode * inode; /* target file of i/o */
76
77 /* completion state */
78 atomic_t io_count; /* i/os we're waiting for */
79 spinlock_t lock; /* protect completion state */
80 ssize_t count, /* bytes actually processed */
81 error; /* any reported error */
82 struct completion completion; /* wait for i/o completion */
83
84 /* commit state */
85 struct list_head rewrite_list; /* saved nfs_write_data structs */
86 struct nfs_write_data * commit_data; /* special write_data for commits */
87 int flags;
88#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
89#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
90 struct nfs_writeverf verf; /* unstable write verifier */
91};
92
93static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
94static const struct rpc_call_ops nfs_write_direct_ops;
95
96static inline void get_dreq(struct nfs_direct_req *dreq)
97{
98 atomic_inc(&dreq->io_count);
99}
100
101static inline int put_dreq(struct nfs_direct_req *dreq)
102{
103 return atomic_dec_and_test(&dreq->io_count);
104}
105
106/**
107 * nfs_direct_IO - NFS address space operation for direct I/O
108 * @rw: direction (read or write)
109 * @iocb: target I/O control block
110 * @iov: array of vectors that define I/O buffer
111 * @pos: offset in file to begin the operation
112 * @nr_segs: size of iovec array
113 *
114 * The presence of this routine in the address space ops vector means
115 * the NFS client supports direct I/O. However, we shunt off direct
116 * read and write requests before the VFS gets them, so this method
117 * should never be called.
118 */
119ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
120{
121 dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
122 iocb->ki_filp->f_path.dentry->d_name.name,
123 (long long) pos, nr_segs);
124
125 return -EINVAL;
126}
127
128static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
129{
130 unsigned int npages;
131 unsigned int i;
132
133 if (count == 0)
134 return;
135 pages += (pgbase >> PAGE_SHIFT);
136 npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
137 for (i = 0; i < npages; i++) {
138 struct page *page = pages[i];
139 if (!PageCompound(page))
140 set_page_dirty(page);
141 }
142}
143
144static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
145{
146 unsigned int i;
147 for (i = 0; i < npages; i++)
148 page_cache_release(pages[i]);
149}
150
151static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
152{
153 struct nfs_direct_req *dreq;
154
155 dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
156 if (!dreq)
157 return NULL;
158
159 kref_init(&dreq->kref);
160 kref_get(&dreq->kref);
161 init_completion(&dreq->completion);
162 INIT_LIST_HEAD(&dreq->rewrite_list);
163 dreq->iocb = NULL;
164 dreq->ctx = NULL;
165 dreq->l_ctx = NULL;
166 spin_lock_init(&dreq->lock);
167 atomic_set(&dreq->io_count, 0);
168 dreq->count = 0;
169 dreq->error = 0;
170 dreq->flags = 0;
171
172 return dreq;
173}
174
175static void nfs_direct_req_free(struct kref *kref)
176{
177 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
178
179 if (dreq->l_ctx != NULL)
180 nfs_put_lock_context(dreq->l_ctx);
181 if (dreq->ctx != NULL)
182 put_nfs_open_context(dreq->ctx);
183 kmem_cache_free(nfs_direct_cachep, dreq);
184}
185
186static void nfs_direct_req_release(struct nfs_direct_req *dreq)
187{
188 kref_put(&dreq->kref, nfs_direct_req_free);
189}
190
191/*
192 * Collects and returns the final error value/byte-count.
193 */
194static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
195{
196 ssize_t result = -EIOCBQUEUED;
197
198 /* Async requests don't wait here */
199 if (dreq->iocb)
200 goto out;
201
202 result = wait_for_completion_killable(&dreq->completion);
203
204 if (!result)
205 result = dreq->error;
206 if (!result)
207 result = dreq->count;
208
209out:
210 return (ssize_t) result;
211}
212
213/*
214 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
215 * the iocb is still valid here if this is a synchronous request.
216 */
217static void nfs_direct_complete(struct nfs_direct_req *dreq)
218{
219 if (dreq->iocb) {
220 long res = (long) dreq->error;
221 if (!res)
222 res = (long) dreq->count;
223 aio_complete(dreq->iocb, res, 0);
224 }
225 complete_all(&dreq->completion);
226
227 nfs_direct_req_release(dreq);
228}
229
230/*
231 * We must hold a reference to all the pages in this direct read request
232 * until the RPCs complete. This could be long *after* we are woken up in
233 * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
234 */
235static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
236{
237 struct nfs_read_data *data = calldata;
238
239 nfs_readpage_result(task, data);
240}
241
242static void nfs_direct_read_release(void *calldata)
243{
244
245 struct nfs_read_data *data = calldata;
246 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
247 int status = data->task.tk_status;
248
249 spin_lock(&dreq->lock);
250 if (unlikely(status < 0)) {
251 dreq->error = status;
252 spin_unlock(&dreq->lock);
253 } else {
254 dreq->count += data->res.count;
255 spin_unlock(&dreq->lock);
256 nfs_direct_dirty_pages(data->pagevec,
257 data->args.pgbase,
258 data->res.count);
259 }
260 nfs_direct_release_pages(data->pagevec, data->npages);
261
262 if (put_dreq(dreq))
263 nfs_direct_complete(dreq);
264 nfs_readdata_free(data);
265}
266
267static const struct rpc_call_ops nfs_read_direct_ops = {
268#if defined(CONFIG_NFS_V4_1)
269 .rpc_call_prepare = nfs_read_prepare,
270#endif /* CONFIG_NFS_V4_1 */
271 .rpc_call_done = nfs_direct_read_result,
272 .rpc_release = nfs_direct_read_release,
273};
274
275/*
276 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
277 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
278 * bail and stop sending more reads. Read length accounting is
279 * handled automatically by nfs_direct_read_result(). Otherwise, if
280 * no requests have been sent, just return an error.
281 */
282static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
283 const struct iovec *iov,
284 loff_t pos)
285{
286 struct nfs_open_context *ctx = dreq->ctx;
287 struct inode *inode = ctx->dentry->d_inode;
288 unsigned long user_addr = (unsigned long)iov->iov_base;
289 size_t count = iov->iov_len;
290 size_t rsize = NFS_SERVER(inode)->rsize;
291 struct rpc_task *task;
292 struct rpc_message msg = {
293 .rpc_cred = ctx->cred,
294 };
295 struct rpc_task_setup task_setup_data = {
296 .rpc_client = NFS_CLIENT(inode),
297 .rpc_message = &msg,
298 .callback_ops = &nfs_read_direct_ops,
299 .workqueue = nfsiod_workqueue,
300 .flags = RPC_TASK_ASYNC,
301 };
302 unsigned int pgbase;
303 int result;
304 ssize_t started = 0;
305
306 do {
307 struct nfs_read_data *data;
308 size_t bytes;
309
310 pgbase = user_addr & ~PAGE_MASK;
311 bytes = min(rsize,count);
312
313 result = -ENOMEM;
314 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
315 if (unlikely(!data))
316 break;
317
318 down_read(¤t->mm->mmap_sem);
319 result = get_user_pages(current, current->mm, user_addr,
320 data->npages, 1, 0, data->pagevec, NULL);
321 up_read(¤t->mm->mmap_sem);
322 if (result < 0) {
323 nfs_readdata_free(data);
324 break;
325 }
326 if ((unsigned)result < data->npages) {
327 bytes = result * PAGE_SIZE;
328 if (bytes <= pgbase) {
329 nfs_direct_release_pages(data->pagevec, result);
330 nfs_readdata_free(data);
331 break;
332 }
333 bytes -= pgbase;
334 data->npages = result;
335 }
336
337 get_dreq(dreq);
338
339 data->req = (struct nfs_page *) dreq;
340 data->inode = inode;
341 data->cred = msg.rpc_cred;
342 data->args.fh = NFS_FH(inode);
343 data->args.context = ctx;
344 data->args.lock_context = dreq->l_ctx;
345 data->args.offset = pos;
346 data->args.pgbase = pgbase;
347 data->args.pages = data->pagevec;
348 data->args.count = bytes;
349 data->res.fattr = &data->fattr;
350 data->res.eof = 0;
351 data->res.count = bytes;
352 nfs_fattr_init(&data->fattr);
353 msg.rpc_argp = &data->args;
354 msg.rpc_resp = &data->res;
355
356 task_setup_data.task = &data->task;
357 task_setup_data.callback_data = data;
358 NFS_PROTO(inode)->read_setup(data, &msg);
359
360 task = rpc_run_task(&task_setup_data);
361 if (IS_ERR(task))
362 break;
363 rpc_put_task(task);
364
365 dprintk("NFS: %5u initiated direct read call "
366 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
367 data->task.tk_pid,
368 inode->i_sb->s_id,
369 (long long)NFS_FILEID(inode),
370 bytes,
371 (unsigned long long)data->args.offset);
372
373 started += bytes;
374 user_addr += bytes;
375 pos += bytes;
376 /* FIXME: Remove this unnecessary math from final patch */
377 pgbase += bytes;
378 pgbase &= ~PAGE_MASK;
379 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
380
381 count -= bytes;
382 } while (count != 0);
383
384 if (started)
385 return started;
386 return result < 0 ? (ssize_t) result : -EFAULT;
387}
388
389static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
390 const struct iovec *iov,
391 unsigned long nr_segs,
392 loff_t pos)
393{
394 ssize_t result = -EINVAL;
395 size_t requested_bytes = 0;
396 unsigned long seg;
397
398 get_dreq(dreq);
399
400 for (seg = 0; seg < nr_segs; seg++) {
401 const struct iovec *vec = &iov[seg];
402 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
403 if (result < 0)
404 break;
405 requested_bytes += result;
406 if ((size_t)result < vec->iov_len)
407 break;
408 pos += vec->iov_len;
409 }
410
411 /*
412 * If no bytes were started, return the error, and let the
413 * generic layer handle the completion.
414 */
415 if (requested_bytes == 0) {
416 nfs_direct_req_release(dreq);
417 return result < 0 ? result : -EIO;
418 }
419
420 if (put_dreq(dreq))
421 nfs_direct_complete(dreq);
422 return 0;
423}
424
425static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
426 unsigned long nr_segs, loff_t pos)
427{
428 ssize_t result = -ENOMEM;
429 struct inode *inode = iocb->ki_filp->f_mapping->host;
430 struct nfs_direct_req *dreq;
431
432 dreq = nfs_direct_req_alloc();
433 if (dreq == NULL)
434 goto out;
435
436 dreq->inode = inode;
437 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
438 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
439 if (dreq->l_ctx == NULL)
440 goto out_release;
441 if (!is_sync_kiocb(iocb))
442 dreq->iocb = iocb;
443
444 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
445 if (!result)
446 result = nfs_direct_wait(dreq);
447out_release:
448 nfs_direct_req_release(dreq);
449out:
450 return result;
451}
452
453static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
454{
455 while (!list_empty(&dreq->rewrite_list)) {
456 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
457 list_del(&data->pages);
458 nfs_direct_release_pages(data->pagevec, data->npages);
459 nfs_writedata_free(data);
460 }
461}
462
463#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
464static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
465{
466 struct inode *inode = dreq->inode;
467 struct list_head *p;
468 struct nfs_write_data *data;
469 struct rpc_task *task;
470 struct rpc_message msg = {
471 .rpc_cred = dreq->ctx->cred,
472 };
473 struct rpc_task_setup task_setup_data = {
474 .rpc_client = NFS_CLIENT(inode),
475 .rpc_message = &msg,
476 .callback_ops = &nfs_write_direct_ops,
477 .workqueue = nfsiod_workqueue,
478 .flags = RPC_TASK_ASYNC,
479 };
480
481 dreq->count = 0;
482 get_dreq(dreq);
483
484 list_for_each(p, &dreq->rewrite_list) {
485 data = list_entry(p, struct nfs_write_data, pages);
486
487 get_dreq(dreq);
488
489 /* Use stable writes */
490 data->args.stable = NFS_FILE_SYNC;
491
492 /*
493 * Reset data->res.
494 */
495 nfs_fattr_init(&data->fattr);
496 data->res.count = data->args.count;
497 memset(&data->verf, 0, sizeof(data->verf));
498
499 /*
500 * Reuse data->task; data->args should not have changed
501 * since the original request was sent.
502 */
503 task_setup_data.task = &data->task;
504 task_setup_data.callback_data = data;
505 msg.rpc_argp = &data->args;
506 msg.rpc_resp = &data->res;
507 NFS_PROTO(inode)->write_setup(data, &msg);
508
509 /*
510 * We're called via an RPC callback, so BKL is already held.
511 */
512 task = rpc_run_task(&task_setup_data);
513 if (!IS_ERR(task))
514 rpc_put_task(task);
515
516 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
517 data->task.tk_pid,
518 inode->i_sb->s_id,
519 (long long)NFS_FILEID(inode),
520 data->args.count,
521 (unsigned long long)data->args.offset);
522 }
523
524 if (put_dreq(dreq))
525 nfs_direct_write_complete(dreq, inode);
526}
527
528static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
529{
530 struct nfs_write_data *data = calldata;
531
532 /* Call the NFS version-specific code */
533 NFS_PROTO(data->inode)->commit_done(task, data);
534}
535
536static void nfs_direct_commit_release(void *calldata)
537{
538 struct nfs_write_data *data = calldata;
539 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
540 int status = data->task.tk_status;
541
542 if (status < 0) {
543 dprintk("NFS: %5u commit failed with error %d.\n",
544 data->task.tk_pid, status);
545 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
546 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
547 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
548 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
549 }
550
551 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
552 nfs_direct_write_complete(dreq, data->inode);
553 nfs_commit_free(data);
554}
555
556static const struct rpc_call_ops nfs_commit_direct_ops = {
557#if defined(CONFIG_NFS_V4_1)
558 .rpc_call_prepare = nfs_write_prepare,
559#endif /* CONFIG_NFS_V4_1 */
560 .rpc_call_done = nfs_direct_commit_result,
561 .rpc_release = nfs_direct_commit_release,
562};
563
564static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
565{
566 struct nfs_write_data *data = dreq->commit_data;
567 struct rpc_task *task;
568 struct rpc_message msg = {
569 .rpc_argp = &data->args,
570 .rpc_resp = &data->res,
571 .rpc_cred = dreq->ctx->cred,
572 };
573 struct rpc_task_setup task_setup_data = {
574 .task = &data->task,
575 .rpc_client = NFS_CLIENT(dreq->inode),
576 .rpc_message = &msg,
577 .callback_ops = &nfs_commit_direct_ops,
578 .callback_data = data,
579 .workqueue = nfsiod_workqueue,
580 .flags = RPC_TASK_ASYNC,
581 };
582
583 data->inode = dreq->inode;
584 data->cred = msg.rpc_cred;
585
586 data->args.fh = NFS_FH(data->inode);
587 data->args.offset = 0;
588 data->args.count = 0;
589 data->args.context = dreq->ctx;
590 data->args.lock_context = dreq->l_ctx;
591 data->res.count = 0;
592 data->res.fattr = &data->fattr;
593 data->res.verf = &data->verf;
594 nfs_fattr_init(&data->fattr);
595
596 NFS_PROTO(data->inode)->commit_setup(data, &msg);
597
598 /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
599 dreq->commit_data = NULL;
600
601 dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
602
603 task = rpc_run_task(&task_setup_data);
604 if (!IS_ERR(task))
605 rpc_put_task(task);
606}
607
608static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
609{
610 int flags = dreq->flags;
611
612 dreq->flags = 0;
613 switch (flags) {
614 case NFS_ODIRECT_DO_COMMIT:
615 nfs_direct_commit_schedule(dreq);
616 break;
617 case NFS_ODIRECT_RESCHED_WRITES:
618 nfs_direct_write_reschedule(dreq);
619 break;
620 default:
621 if (dreq->commit_data != NULL)
622 nfs_commit_free(dreq->commit_data);
623 nfs_direct_free_writedata(dreq);
624 nfs_zap_mapping(inode, inode->i_mapping);
625 nfs_direct_complete(dreq);
626 }
627}
628
629static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
630{
631 dreq->commit_data = nfs_commitdata_alloc();
632 if (dreq->commit_data != NULL)
633 dreq->commit_data->req = (struct nfs_page *) dreq;
634}
635#else
636static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
637{
638 dreq->commit_data = NULL;
639}
640
641static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
642{
643 nfs_direct_free_writedata(dreq);
644 nfs_zap_mapping(inode, inode->i_mapping);
645 nfs_direct_complete(dreq);
646}
647#endif
648
649static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
650{
651 struct nfs_write_data *data = calldata;
652
653 nfs_writeback_done(task, data);
654}
655
656/*
657 * NB: Return the value of the first error return code. Subsequent
658 * errors after the first one are ignored.
659 */
660static void nfs_direct_write_release(void *calldata)
661{
662 struct nfs_write_data *data = calldata;
663 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
664 int status = data->task.tk_status;
665
666 spin_lock(&dreq->lock);
667
668 if (unlikely(status < 0)) {
669 /* An error has occurred, so we should not commit */
670 dreq->flags = 0;
671 dreq->error = status;
672 }
673 if (unlikely(dreq->error != 0))
674 goto out_unlock;
675
676 dreq->count += data->res.count;
677
678 if (data->res.verf->committed != NFS_FILE_SYNC) {
679 switch (dreq->flags) {
680 case 0:
681 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
682 dreq->flags = NFS_ODIRECT_DO_COMMIT;
683 break;
684 case NFS_ODIRECT_DO_COMMIT:
685 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
686 dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
687 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
688 }
689 }
690 }
691out_unlock:
692 spin_unlock(&dreq->lock);
693
694 if (put_dreq(dreq))
695 nfs_direct_write_complete(dreq, data->inode);
696}
697
698static const struct rpc_call_ops nfs_write_direct_ops = {
699#if defined(CONFIG_NFS_V4_1)
700 .rpc_call_prepare = nfs_write_prepare,
701#endif /* CONFIG_NFS_V4_1 */
702 .rpc_call_done = nfs_direct_write_result,
703 .rpc_release = nfs_direct_write_release,
704};
705
706/*
707 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
708 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
709 * bail and stop sending more writes. Write length accounting is
710 * handled automatically by nfs_direct_write_result(). Otherwise, if
711 * no requests have been sent, just return an error.
712 */
713static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
714 const struct iovec *iov,
715 loff_t pos, int sync)
716{
717 struct nfs_open_context *ctx = dreq->ctx;
718 struct inode *inode = ctx->dentry->d_inode;
719 unsigned long user_addr = (unsigned long)iov->iov_base;
720 size_t count = iov->iov_len;
721 struct rpc_task *task;
722 struct rpc_message msg = {
723 .rpc_cred = ctx->cred,
724 };
725 struct rpc_task_setup task_setup_data = {
726 .rpc_client = NFS_CLIENT(inode),
727 .rpc_message = &msg,
728 .callback_ops = &nfs_write_direct_ops,
729 .workqueue = nfsiod_workqueue,
730 .flags = RPC_TASK_ASYNC,
731 };
732 size_t wsize = NFS_SERVER(inode)->wsize;
733 unsigned int pgbase;
734 int result;
735 ssize_t started = 0;
736
737 do {
738 struct nfs_write_data *data;
739 size_t bytes;
740
741 pgbase = user_addr & ~PAGE_MASK;
742 bytes = min(wsize,count);
743
744 result = -ENOMEM;
745 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
746 if (unlikely(!data))
747 break;
748
749 down_read(¤t->mm->mmap_sem);
750 result = get_user_pages(current, current->mm, user_addr,
751 data->npages, 0, 0, data->pagevec, NULL);
752 up_read(¤t->mm->mmap_sem);
753 if (result < 0) {
754 nfs_writedata_free(data);
755 break;
756 }
757 if ((unsigned)result < data->npages) {
758 bytes = result * PAGE_SIZE;
759 if (bytes <= pgbase) {
760 nfs_direct_release_pages(data->pagevec, result);
761 nfs_writedata_free(data);
762 break;
763 }
764 bytes -= pgbase;
765 data->npages = result;
766 }
767
768 get_dreq(dreq);
769
770 list_move_tail(&data->pages, &dreq->rewrite_list);
771
772 data->req = (struct nfs_page *) dreq;
773 data->inode = inode;
774 data->cred = msg.rpc_cred;
775 data->args.fh = NFS_FH(inode);
776 data->args.context = ctx;
777 data->args.lock_context = dreq->l_ctx;
778 data->args.offset = pos;
779 data->args.pgbase = pgbase;
780 data->args.pages = data->pagevec;
781 data->args.count = bytes;
782 data->args.stable = sync;
783 data->res.fattr = &data->fattr;
784 data->res.count = bytes;
785 data->res.verf = &data->verf;
786 nfs_fattr_init(&data->fattr);
787
788 task_setup_data.task = &data->task;
789 task_setup_data.callback_data = data;
790 msg.rpc_argp = &data->args;
791 msg.rpc_resp = &data->res;
792 NFS_PROTO(inode)->write_setup(data, &msg);
793
794 task = rpc_run_task(&task_setup_data);
795 if (IS_ERR(task))
796 break;
797 rpc_put_task(task);
798
799 dprintk("NFS: %5u initiated direct write call "
800 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
801 data->task.tk_pid,
802 inode->i_sb->s_id,
803 (long long)NFS_FILEID(inode),
804 bytes,
805 (unsigned long long)data->args.offset);
806
807 started += bytes;
808 user_addr += bytes;
809 pos += bytes;
810
811 /* FIXME: Remove this useless math from the final patch */
812 pgbase += bytes;
813 pgbase &= ~PAGE_MASK;
814 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
815
816 count -= bytes;
817 } while (count != 0);
818
819 if (started)
820 return started;
821 return result < 0 ? (ssize_t) result : -EFAULT;
822}
823
824static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
825 const struct iovec *iov,
826 unsigned long nr_segs,
827 loff_t pos, int sync)
828{
829 ssize_t result = 0;
830 size_t requested_bytes = 0;
831 unsigned long seg;
832
833 get_dreq(dreq);
834
835 for (seg = 0; seg < nr_segs; seg++) {
836 const struct iovec *vec = &iov[seg];
837 result = nfs_direct_write_schedule_segment(dreq, vec,
838 pos, sync);
839 if (result < 0)
840 break;
841 requested_bytes += result;
842 if ((size_t)result < vec->iov_len)
843 break;
844 pos += vec->iov_len;
845 }
846
847 /*
848 * If no bytes were started, return the error, and let the
849 * generic layer handle the completion.
850 */
851 if (requested_bytes == 0) {
852 nfs_direct_req_release(dreq);
853 return result < 0 ? result : -EIO;
854 }
855
856 if (put_dreq(dreq))
857 nfs_direct_write_complete(dreq, dreq->inode);
858 return 0;
859}
860
861static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
862 unsigned long nr_segs, loff_t pos,
863 size_t count)
864{
865 ssize_t result = -ENOMEM;
866 struct inode *inode = iocb->ki_filp->f_mapping->host;
867 struct nfs_direct_req *dreq;
868 size_t wsize = NFS_SERVER(inode)->wsize;
869 int sync = NFS_UNSTABLE;
870
871 dreq = nfs_direct_req_alloc();
872 if (!dreq)
873 goto out;
874 nfs_alloc_commit_data(dreq);
875
876 if (dreq->commit_data == NULL || count <= wsize)
877 sync = NFS_FILE_SYNC;
878
879 dreq->inode = inode;
880 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
881 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
882 if (dreq->l_ctx == NULL)
883 goto out_release;
884 if (!is_sync_kiocb(iocb))
885 dreq->iocb = iocb;
886
887 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
888 if (!result)
889 result = nfs_direct_wait(dreq);
890out_release:
891 nfs_direct_req_release(dreq);
892out:
893 return result;
894}
895
896/**
897 * nfs_file_direct_read - file direct read operation for NFS files
898 * @iocb: target I/O control block
899 * @iov: vector of user buffers into which to read data
900 * @nr_segs: size of iov vector
901 * @pos: byte offset in file where reading starts
902 *
903 * We use this function for direct reads instead of calling
904 * generic_file_aio_read() in order to avoid gfar's check to see if
905 * the request starts before the end of the file. For that check
906 * to work, we must generate a GETATTR before each direct read, and
907 * even then there is a window between the GETATTR and the subsequent
908 * READ where the file size could change. Our preference is simply
909 * to do all reads the application wants, and the server will take
910 * care of managing the end of file boundary.
911 *
912 * This function also eliminates unnecessarily updating the file's
913 * atime locally, as the NFS server sets the file's atime, and this
914 * client must read the updated atime from the server back into its
915 * cache.
916 */
917ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
918 unsigned long nr_segs, loff_t pos)
919{
920 ssize_t retval = -EINVAL;
921 struct file *file = iocb->ki_filp;
922 struct address_space *mapping = file->f_mapping;
923 size_t count;
924
925 count = iov_length(iov, nr_segs);
926 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
927
928 dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
929 file->f_path.dentry->d_parent->d_name.name,
930 file->f_path.dentry->d_name.name,
931 count, (long long) pos);
932
933 retval = 0;
934 if (!count)
935 goto out;
936
937 retval = nfs_sync_mapping(mapping);
938 if (retval)
939 goto out;
940
941 task_io_account_read(count);
942
943 retval = nfs_direct_read(iocb, iov, nr_segs, pos);
944 if (retval > 0)
945 iocb->ki_pos = pos + retval;
946
947out:
948 return retval;
949}
950
951/**
952 * nfs_file_direct_write - file direct write operation for NFS files
953 * @iocb: target I/O control block
954 * @iov: vector of user buffers from which to write data
955 * @nr_segs: size of iov vector
956 * @pos: byte offset in file where writing starts
957 *
958 * We use this function for direct writes instead of calling
959 * generic_file_aio_write() in order to avoid taking the inode
960 * semaphore and updating the i_size. The NFS server will set
961 * the new i_size and this client must read the updated size
962 * back into its cache. We let the server do generic write
963 * parameter checking and report problems.
964 *
965 * We eliminate local atime updates, see direct read above.
966 *
967 * We avoid unnecessary page cache invalidations for normal cached
968 * readers of this file.
969 *
970 * Note that O_APPEND is not supported for NFS direct writes, as there
971 * is no atomic O_APPEND write facility in the NFS protocol.
972 */
973ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
974 unsigned long nr_segs, loff_t pos)
975{
976 ssize_t retval = -EINVAL;
977 struct file *file = iocb->ki_filp;
978 struct address_space *mapping = file->f_mapping;
979 size_t count;
980
981 count = iov_length(iov, nr_segs);
982 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
983
984 dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
985 file->f_path.dentry->d_parent->d_name.name,
986 file->f_path.dentry->d_name.name,
987 count, (long long) pos);
988
989 retval = generic_write_checks(file, &pos, &count, 0);
990 if (retval)
991 goto out;
992
993 retval = -EINVAL;
994 if ((ssize_t) count < 0)
995 goto out;
996 retval = 0;
997 if (!count)
998 goto out;
999
1000 retval = nfs_sync_mapping(mapping);
1001 if (retval)
1002 goto out;
1003
1004 task_io_account_write(count);
1005
1006 retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
1007
1008 if (retval > 0)
1009 iocb->ki_pos = pos + retval;
1010
1011out:
1012 return retval;
1013}
1014
1015/**
1016 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1017 *
1018 */
1019int __init nfs_init_directcache(void)
1020{
1021 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1022 sizeof(struct nfs_direct_req),
1023 0, (SLAB_RECLAIM_ACCOUNT|
1024 SLAB_MEM_SPREAD),
1025 NULL);
1026 if (nfs_direct_cachep == NULL)
1027 return -ENOMEM;
1028
1029 return 0;
1030}
1031
1032/**
1033 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1034 *
1035 */
1036void nfs_destroy_directcache(void)
1037{
1038 kmem_cache_destroy(nfs_direct_cachep);
1039}
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
63#define NFSDBG_FACILITY NFSDBG_VFS
64
65static struct kmem_cache *nfs_direct_cachep;
66
67struct nfs_direct_req {
68 struct kref kref; /* release manager */
69
70 /* I/O parameters */
71 struct nfs_open_context *ctx; /* file open context info */
72 struct nfs_lock_context *l_ctx; /* Lock context info */
73 struct kiocb * iocb; /* controlling i/o request */
74 struct inode * inode; /* target file of i/o */
75
76 /* completion state */
77 atomic_t io_count; /* i/os we're waiting for */
78 spinlock_t lock; /* protect completion state */
79
80 loff_t io_start; /* Start offset for I/O */
81 ssize_t count, /* bytes actually processed */
82 max_count, /* max expected count */
83 bytes_left, /* bytes left to be sent */
84 error; /* any reported error */
85 struct completion completion; /* wait for i/o completion */
86
87 /* commit state */
88 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
89 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
90 struct work_struct work;
91 int flags;
92 /* for write */
93#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
94#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
95 /* for read */
96#define NFS_ODIRECT_SHOULD_DIRTY (3) /* dirty user-space page after read */
97#define NFS_ODIRECT_DONE INT_MAX /* write verification failed */
98};
99
100static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
101static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
102static void nfs_direct_write_complete(struct nfs_direct_req *dreq);
103static void nfs_direct_write_schedule_work(struct work_struct *work);
104
105static inline void get_dreq(struct nfs_direct_req *dreq)
106{
107 atomic_inc(&dreq->io_count);
108}
109
110static inline int put_dreq(struct nfs_direct_req *dreq)
111{
112 return atomic_dec_and_test(&dreq->io_count);
113}
114
115static void
116nfs_direct_handle_truncated(struct nfs_direct_req *dreq,
117 const struct nfs_pgio_header *hdr,
118 ssize_t dreq_len)
119{
120 if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||
121 test_bit(NFS_IOHDR_EOF, &hdr->flags)))
122 return;
123 if (dreq->max_count >= dreq_len) {
124 dreq->max_count = dreq_len;
125 if (dreq->count > dreq_len)
126 dreq->count = dreq_len;
127
128 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
129 dreq->error = hdr->error;
130 else /* Clear outstanding error if this is EOF */
131 dreq->error = 0;
132 }
133}
134
135static void
136nfs_direct_count_bytes(struct nfs_direct_req *dreq,
137 const struct nfs_pgio_header *hdr)
138{
139 loff_t hdr_end = hdr->io_start + hdr->good_bytes;
140 ssize_t dreq_len = 0;
141
142 if (hdr_end > dreq->io_start)
143 dreq_len = hdr_end - dreq->io_start;
144
145 nfs_direct_handle_truncated(dreq, hdr, dreq_len);
146
147 if (dreq_len > dreq->max_count)
148 dreq_len = dreq->max_count;
149
150 if (dreq->count < dreq_len)
151 dreq->count = dreq_len;
152}
153
154/**
155 * nfs_direct_IO - NFS address space operation for direct I/O
156 * @iocb: target I/O control block
157 * @iter: I/O buffer
158 *
159 * The presence of this routine in the address space ops vector means
160 * the NFS client supports direct I/O. However, for most direct IO, we
161 * shunt off direct read and write requests before the VFS gets them,
162 * so this method is only ever called for swap.
163 */
164ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
165{
166 struct inode *inode = iocb->ki_filp->f_mapping->host;
167
168 /* we only support swap file calling nfs_direct_IO */
169 if (!IS_SWAPFILE(inode))
170 return 0;
171
172 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE);
173
174 if (iov_iter_rw(iter) == READ)
175 return nfs_file_direct_read(iocb, iter);
176 return nfs_file_direct_write(iocb, iter);
177}
178
179static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
180{
181 unsigned int i;
182 for (i = 0; i < npages; i++)
183 put_page(pages[i]);
184}
185
186void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
187 struct nfs_direct_req *dreq)
188{
189 cinfo->inode = dreq->inode;
190 cinfo->mds = &dreq->mds_cinfo;
191 cinfo->ds = &dreq->ds_cinfo;
192 cinfo->dreq = dreq;
193 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
194}
195
196static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
197{
198 struct nfs_direct_req *dreq;
199
200 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
201 if (!dreq)
202 return NULL;
203
204 kref_init(&dreq->kref);
205 kref_get(&dreq->kref);
206 init_completion(&dreq->completion);
207 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
208 pnfs_init_ds_commit_info(&dreq->ds_cinfo);
209 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
210 spin_lock_init(&dreq->lock);
211
212 return dreq;
213}
214
215static void nfs_direct_req_free(struct kref *kref)
216{
217 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
218
219 pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode);
220 if (dreq->l_ctx != NULL)
221 nfs_put_lock_context(dreq->l_ctx);
222 if (dreq->ctx != NULL)
223 put_nfs_open_context(dreq->ctx);
224 kmem_cache_free(nfs_direct_cachep, dreq);
225}
226
227static void nfs_direct_req_release(struct nfs_direct_req *dreq)
228{
229 kref_put(&dreq->kref, nfs_direct_req_free);
230}
231
232ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
233{
234 return dreq->bytes_left;
235}
236EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
237
238/*
239 * Collects and returns the final error value/byte-count.
240 */
241static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
242{
243 ssize_t result = -EIOCBQUEUED;
244
245 /* Async requests don't wait here */
246 if (dreq->iocb)
247 goto out;
248
249 result = wait_for_completion_killable(&dreq->completion);
250
251 if (!result) {
252 result = dreq->count;
253 WARN_ON_ONCE(dreq->count < 0);
254 }
255 if (!result)
256 result = dreq->error;
257
258out:
259 return (ssize_t) result;
260}
261
262/*
263 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
264 * the iocb is still valid here if this is a synchronous request.
265 */
266static void nfs_direct_complete(struct nfs_direct_req *dreq)
267{
268 struct inode *inode = dreq->inode;
269
270 inode_dio_end(inode);
271
272 if (dreq->iocb) {
273 long res = (long) dreq->error;
274 if (dreq->count != 0) {
275 res = (long) dreq->count;
276 WARN_ON_ONCE(dreq->count < 0);
277 }
278 dreq->iocb->ki_complete(dreq->iocb, res, 0);
279 }
280
281 complete(&dreq->completion);
282
283 nfs_direct_req_release(dreq);
284}
285
286static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
287{
288 unsigned long bytes = 0;
289 struct nfs_direct_req *dreq = hdr->dreq;
290
291 spin_lock(&dreq->lock);
292 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
293 spin_unlock(&dreq->lock);
294 goto out_put;
295 }
296
297 nfs_direct_count_bytes(dreq, hdr);
298 spin_unlock(&dreq->lock);
299
300 while (!list_empty(&hdr->pages)) {
301 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
302 struct page *page = req->wb_page;
303
304 if (!PageCompound(page) && bytes < hdr->good_bytes &&
305 (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
306 set_page_dirty(page);
307 bytes += req->wb_bytes;
308 nfs_list_remove_request(req);
309 nfs_release_request(req);
310 }
311out_put:
312 if (put_dreq(dreq))
313 nfs_direct_complete(dreq);
314 hdr->release(hdr);
315}
316
317static void nfs_read_sync_pgio_error(struct list_head *head, int error)
318{
319 struct nfs_page *req;
320
321 while (!list_empty(head)) {
322 req = nfs_list_entry(head->next);
323 nfs_list_remove_request(req);
324 nfs_release_request(req);
325 }
326}
327
328static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
329{
330 get_dreq(hdr->dreq);
331}
332
333static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
334 .error_cleanup = nfs_read_sync_pgio_error,
335 .init_hdr = nfs_direct_pgio_init,
336 .completion = nfs_direct_read_completion,
337};
338
339/*
340 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
341 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
342 * bail and stop sending more reads. Read length accounting is
343 * handled automatically by nfs_direct_read_result(). Otherwise, if
344 * no requests have been sent, just return an error.
345 */
346
347static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
348 struct iov_iter *iter,
349 loff_t pos)
350{
351 struct nfs_pageio_descriptor desc;
352 struct inode *inode = dreq->inode;
353 ssize_t result = -EINVAL;
354 size_t requested_bytes = 0;
355 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
356
357 nfs_pageio_init_read(&desc, dreq->inode, false,
358 &nfs_direct_read_completion_ops);
359 get_dreq(dreq);
360 desc.pg_dreq = dreq;
361 inode_dio_begin(inode);
362
363 while (iov_iter_count(iter)) {
364 struct page **pagevec;
365 size_t bytes;
366 size_t pgbase;
367 unsigned npages, i;
368
369 result = iov_iter_get_pages_alloc(iter, &pagevec,
370 rsize, &pgbase);
371 if (result < 0)
372 break;
373
374 bytes = result;
375 iov_iter_advance(iter, bytes);
376 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
377 for (i = 0; i < npages; i++) {
378 struct nfs_page *req;
379 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
380 /* XXX do we need to do the eof zeroing found in async_filler? */
381 req = nfs_create_request(dreq->ctx, pagevec[i],
382 pgbase, req_len);
383 if (IS_ERR(req)) {
384 result = PTR_ERR(req);
385 break;
386 }
387 req->wb_index = pos >> PAGE_SHIFT;
388 req->wb_offset = pos & ~PAGE_MASK;
389 if (!nfs_pageio_add_request(&desc, req)) {
390 result = desc.pg_error;
391 nfs_release_request(req);
392 break;
393 }
394 pgbase = 0;
395 bytes -= req_len;
396 requested_bytes += req_len;
397 pos += req_len;
398 dreq->bytes_left -= req_len;
399 }
400 nfs_direct_release_pages(pagevec, npages);
401 kvfree(pagevec);
402 if (result < 0)
403 break;
404 }
405
406 nfs_pageio_complete(&desc);
407
408 /*
409 * If no bytes were started, return the error, and let the
410 * generic layer handle the completion.
411 */
412 if (requested_bytes == 0) {
413 inode_dio_end(inode);
414 nfs_direct_req_release(dreq);
415 return result < 0 ? result : -EIO;
416 }
417
418 if (put_dreq(dreq))
419 nfs_direct_complete(dreq);
420 return requested_bytes;
421}
422
423/**
424 * nfs_file_direct_read - file direct read operation for NFS files
425 * @iocb: target I/O control block
426 * @iter: vector of user buffers into which to read data
427 *
428 * We use this function for direct reads instead of calling
429 * generic_file_aio_read() in order to avoid gfar's check to see if
430 * the request starts before the end of the file. For that check
431 * to work, we must generate a GETATTR before each direct read, and
432 * even then there is a window between the GETATTR and the subsequent
433 * READ where the file size could change. Our preference is simply
434 * to do all reads the application wants, and the server will take
435 * care of managing the end of file boundary.
436 *
437 * This function also eliminates unnecessarily updating the file's
438 * atime locally, as the NFS server sets the file's atime, and this
439 * client must read the updated atime from the server back into its
440 * cache.
441 */
442ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
443{
444 struct file *file = iocb->ki_filp;
445 struct address_space *mapping = file->f_mapping;
446 struct inode *inode = mapping->host;
447 struct nfs_direct_req *dreq;
448 struct nfs_lock_context *l_ctx;
449 ssize_t result, requested;
450 size_t count = iov_iter_count(iter);
451 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
452
453 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
454 file, count, (long long) iocb->ki_pos);
455
456 result = 0;
457 if (!count)
458 goto out;
459
460 task_io_account_read(count);
461
462 result = -ENOMEM;
463 dreq = nfs_direct_req_alloc();
464 if (dreq == NULL)
465 goto out;
466
467 dreq->inode = inode;
468 dreq->bytes_left = dreq->max_count = count;
469 dreq->io_start = iocb->ki_pos;
470 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
471 l_ctx = nfs_get_lock_context(dreq->ctx);
472 if (IS_ERR(l_ctx)) {
473 result = PTR_ERR(l_ctx);
474 nfs_direct_req_release(dreq);
475 goto out_release;
476 }
477 dreq->l_ctx = l_ctx;
478 if (!is_sync_kiocb(iocb))
479 dreq->iocb = iocb;
480
481 if (iter_is_iovec(iter))
482 dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
483
484 nfs_start_io_direct(inode);
485
486 NFS_I(inode)->read_io += count;
487 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
488
489 nfs_end_io_direct(inode);
490
491 if (requested > 0) {
492 result = nfs_direct_wait(dreq);
493 if (result > 0) {
494 requested -= result;
495 iocb->ki_pos += result;
496 }
497 iov_iter_revert(iter, requested);
498 } else {
499 result = requested;
500 }
501
502out_release:
503 nfs_direct_req_release(dreq);
504out:
505 return result;
506}
507
508static void
509nfs_direct_join_group(struct list_head *list, struct inode *inode)
510{
511 struct nfs_page *req, *next;
512
513 list_for_each_entry(req, list, wb_list) {
514 if (req->wb_head != req || req->wb_this_page == req)
515 continue;
516 for (next = req->wb_this_page;
517 next != req->wb_head;
518 next = next->wb_this_page) {
519 nfs_list_remove_request(next);
520 nfs_release_request(next);
521 }
522 nfs_join_page_group(req, inode);
523 }
524}
525
526static void
527nfs_direct_write_scan_commit_list(struct inode *inode,
528 struct list_head *list,
529 struct nfs_commit_info *cinfo)
530{
531 mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
532 pnfs_recover_commit_reqs(list, cinfo);
533 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
534 mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
535}
536
537static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
538{
539 struct nfs_pageio_descriptor desc;
540 struct nfs_page *req, *tmp;
541 LIST_HEAD(reqs);
542 struct nfs_commit_info cinfo;
543 LIST_HEAD(failed);
544
545 nfs_init_cinfo_from_dreq(&cinfo, dreq);
546 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
547
548 nfs_direct_join_group(&reqs, dreq->inode);
549
550 dreq->count = 0;
551 dreq->max_count = 0;
552 list_for_each_entry(req, &reqs, wb_list)
553 dreq->max_count += req->wb_bytes;
554 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
555 get_dreq(dreq);
556
557 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
558 &nfs_direct_write_completion_ops);
559 desc.pg_dreq = dreq;
560
561 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
562 /* Bump the transmission count */
563 req->wb_nio++;
564 if (!nfs_pageio_add_request(&desc, req)) {
565 nfs_list_move_request(req, &failed);
566 spin_lock(&cinfo.inode->i_lock);
567 dreq->flags = 0;
568 if (desc.pg_error < 0)
569 dreq->error = desc.pg_error;
570 else
571 dreq->error = -EIO;
572 spin_unlock(&cinfo.inode->i_lock);
573 }
574 nfs_release_request(req);
575 }
576 nfs_pageio_complete(&desc);
577
578 while (!list_empty(&failed)) {
579 req = nfs_list_entry(failed.next);
580 nfs_list_remove_request(req);
581 nfs_unlock_and_release_request(req);
582 }
583
584 if (put_dreq(dreq))
585 nfs_direct_write_complete(dreq);
586}
587
588static void nfs_direct_commit_complete(struct nfs_commit_data *data)
589{
590 const struct nfs_writeverf *verf = data->res.verf;
591 struct nfs_direct_req *dreq = data->dreq;
592 struct nfs_commit_info cinfo;
593 struct nfs_page *req;
594 int status = data->task.tk_status;
595
596 if (status < 0) {
597 /* Errors in commit are fatal */
598 dreq->error = status;
599 dreq->max_count = 0;
600 dreq->count = 0;
601 dreq->flags = NFS_ODIRECT_DONE;
602 } else if (dreq->flags == NFS_ODIRECT_DONE)
603 status = dreq->error;
604
605 nfs_init_cinfo_from_dreq(&cinfo, dreq);
606
607 while (!list_empty(&data->pages)) {
608 req = nfs_list_entry(data->pages.next);
609 nfs_list_remove_request(req);
610 if (status >= 0 && !nfs_write_match_verf(verf, req)) {
611 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
612 /*
613 * Despite the reboot, the write was successful,
614 * so reset wb_nio.
615 */
616 req->wb_nio = 0;
617 nfs_mark_request_commit(req, NULL, &cinfo, 0);
618 } else /* Error or match */
619 nfs_release_request(req);
620 nfs_unlock_and_release_request(req);
621 }
622
623 if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
624 nfs_direct_write_complete(dreq);
625}
626
627static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
628 struct nfs_page *req)
629{
630 struct nfs_direct_req *dreq = cinfo->dreq;
631
632 spin_lock(&dreq->lock);
633 if (dreq->flags != NFS_ODIRECT_DONE)
634 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
635 spin_unlock(&dreq->lock);
636 nfs_mark_request_commit(req, NULL, cinfo, 0);
637}
638
639static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
640 .completion = nfs_direct_commit_complete,
641 .resched_write = nfs_direct_resched_write,
642};
643
644static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
645{
646 int res;
647 struct nfs_commit_info cinfo;
648 LIST_HEAD(mds_list);
649
650 nfs_init_cinfo_from_dreq(&cinfo, dreq);
651 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
652 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
653 if (res < 0) /* res == -ENOMEM */
654 nfs_direct_write_reschedule(dreq);
655}
656
657static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)
658{
659 struct nfs_commit_info cinfo;
660 struct nfs_page *req;
661 LIST_HEAD(reqs);
662
663 nfs_init_cinfo_from_dreq(&cinfo, dreq);
664 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
665
666 while (!list_empty(&reqs)) {
667 req = nfs_list_entry(reqs.next);
668 nfs_list_remove_request(req);
669 nfs_release_request(req);
670 nfs_unlock_and_release_request(req);
671 }
672}
673
674static void nfs_direct_write_schedule_work(struct work_struct *work)
675{
676 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
677 int flags = dreq->flags;
678
679 dreq->flags = 0;
680 switch (flags) {
681 case NFS_ODIRECT_DO_COMMIT:
682 nfs_direct_commit_schedule(dreq);
683 break;
684 case NFS_ODIRECT_RESCHED_WRITES:
685 nfs_direct_write_reschedule(dreq);
686 break;
687 default:
688 nfs_direct_write_clear_reqs(dreq);
689 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
690 nfs_direct_complete(dreq);
691 }
692}
693
694static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
695{
696 queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */
697}
698
699static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
700{
701 struct nfs_direct_req *dreq = hdr->dreq;
702 struct nfs_commit_info cinfo;
703 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
704 int flags = NFS_ODIRECT_DONE;
705
706 nfs_init_cinfo_from_dreq(&cinfo, dreq);
707
708 spin_lock(&dreq->lock);
709 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
710 spin_unlock(&dreq->lock);
711 goto out_put;
712 }
713
714 nfs_direct_count_bytes(dreq, hdr);
715 if (hdr->good_bytes != 0 && nfs_write_need_commit(hdr)) {
716 if (!dreq->flags)
717 dreq->flags = NFS_ODIRECT_DO_COMMIT;
718 flags = dreq->flags;
719 }
720 spin_unlock(&dreq->lock);
721
722 while (!list_empty(&hdr->pages)) {
723
724 req = nfs_list_entry(hdr->pages.next);
725 nfs_list_remove_request(req);
726 if (flags == NFS_ODIRECT_DO_COMMIT) {
727 kref_get(&req->wb_kref);
728 memcpy(&req->wb_verf, &hdr->verf.verifier,
729 sizeof(req->wb_verf));
730 nfs_mark_request_commit(req, hdr->lseg, &cinfo,
731 hdr->ds_commit_idx);
732 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
733 kref_get(&req->wb_kref);
734 nfs_mark_request_commit(req, NULL, &cinfo, 0);
735 }
736 nfs_unlock_and_release_request(req);
737 }
738
739out_put:
740 if (put_dreq(dreq))
741 nfs_direct_write_complete(dreq);
742 hdr->release(hdr);
743}
744
745static void nfs_write_sync_pgio_error(struct list_head *head, int error)
746{
747 struct nfs_page *req;
748
749 while (!list_empty(head)) {
750 req = nfs_list_entry(head->next);
751 nfs_list_remove_request(req);
752 nfs_unlock_and_release_request(req);
753 }
754}
755
756static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
757{
758 struct nfs_direct_req *dreq = hdr->dreq;
759
760 spin_lock(&dreq->lock);
761 if (dreq->error == 0) {
762 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
763 /* fake unstable write to let common nfs resend pages */
764 hdr->verf.committed = NFS_UNSTABLE;
765 hdr->good_bytes = hdr->args.offset + hdr->args.count -
766 hdr->io_start;
767 }
768 spin_unlock(&dreq->lock);
769}
770
771static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
772 .error_cleanup = nfs_write_sync_pgio_error,
773 .init_hdr = nfs_direct_pgio_init,
774 .completion = nfs_direct_write_completion,
775 .reschedule_io = nfs_direct_write_reschedule_io,
776};
777
778
779/*
780 * NB: Return the value of the first error return code. Subsequent
781 * errors after the first one are ignored.
782 */
783/*
784 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
785 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
786 * bail and stop sending more writes. Write length accounting is
787 * handled automatically by nfs_direct_write_result(). Otherwise, if
788 * no requests have been sent, just return an error.
789 */
790static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
791 struct iov_iter *iter,
792 loff_t pos)
793{
794 struct nfs_pageio_descriptor desc;
795 struct inode *inode = dreq->inode;
796 ssize_t result = 0;
797 size_t requested_bytes = 0;
798 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
799
800 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false,
801 &nfs_direct_write_completion_ops);
802 desc.pg_dreq = dreq;
803 get_dreq(dreq);
804 inode_dio_begin(inode);
805
806 NFS_I(inode)->write_io += iov_iter_count(iter);
807 while (iov_iter_count(iter)) {
808 struct page **pagevec;
809 size_t bytes;
810 size_t pgbase;
811 unsigned npages, i;
812
813 result = iov_iter_get_pages_alloc(iter, &pagevec,
814 wsize, &pgbase);
815 if (result < 0)
816 break;
817
818 bytes = result;
819 iov_iter_advance(iter, bytes);
820 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
821 for (i = 0; i < npages; i++) {
822 struct nfs_page *req;
823 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
824
825 req = nfs_create_request(dreq->ctx, pagevec[i],
826 pgbase, req_len);
827 if (IS_ERR(req)) {
828 result = PTR_ERR(req);
829 break;
830 }
831
832 if (desc.pg_error < 0) {
833 nfs_free_request(req);
834 result = desc.pg_error;
835 break;
836 }
837
838 nfs_lock_request(req);
839 req->wb_index = pos >> PAGE_SHIFT;
840 req->wb_offset = pos & ~PAGE_MASK;
841 if (!nfs_pageio_add_request(&desc, req)) {
842 result = desc.pg_error;
843 nfs_unlock_and_release_request(req);
844 break;
845 }
846 pgbase = 0;
847 bytes -= req_len;
848 requested_bytes += req_len;
849 pos += req_len;
850 dreq->bytes_left -= req_len;
851 }
852 nfs_direct_release_pages(pagevec, npages);
853 kvfree(pagevec);
854 if (result < 0)
855 break;
856 }
857 nfs_pageio_complete(&desc);
858
859 /*
860 * If no bytes were started, return the error, and let the
861 * generic layer handle the completion.
862 */
863 if (requested_bytes == 0) {
864 inode_dio_end(inode);
865 nfs_direct_req_release(dreq);
866 return result < 0 ? result : -EIO;
867 }
868
869 if (put_dreq(dreq))
870 nfs_direct_write_complete(dreq);
871 return requested_bytes;
872}
873
874/**
875 * nfs_file_direct_write - file direct write operation for NFS files
876 * @iocb: target I/O control block
877 * @iter: vector of user buffers from which to write data
878 *
879 * We use this function for direct writes instead of calling
880 * generic_file_aio_write() in order to avoid taking the inode
881 * semaphore and updating the i_size. The NFS server will set
882 * the new i_size and this client must read the updated size
883 * back into its cache. We let the server do generic write
884 * parameter checking and report problems.
885 *
886 * We eliminate local atime updates, see direct read above.
887 *
888 * We avoid unnecessary page cache invalidations for normal cached
889 * readers of this file.
890 *
891 * Note that O_APPEND is not supported for NFS direct writes, as there
892 * is no atomic O_APPEND write facility in the NFS protocol.
893 */
894ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
895{
896 ssize_t result, requested;
897 size_t count;
898 struct file *file = iocb->ki_filp;
899 struct address_space *mapping = file->f_mapping;
900 struct inode *inode = mapping->host;
901 struct nfs_direct_req *dreq;
902 struct nfs_lock_context *l_ctx;
903 loff_t pos, end;
904
905 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
906 file, iov_iter_count(iter), (long long) iocb->ki_pos);
907
908 result = generic_write_checks(iocb, iter);
909 if (result <= 0)
910 return result;
911 count = result;
912 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
913
914 pos = iocb->ki_pos;
915 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
916
917 task_io_account_write(count);
918
919 result = -ENOMEM;
920 dreq = nfs_direct_req_alloc();
921 if (!dreq)
922 goto out;
923
924 dreq->inode = inode;
925 dreq->bytes_left = dreq->max_count = count;
926 dreq->io_start = pos;
927 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
928 l_ctx = nfs_get_lock_context(dreq->ctx);
929 if (IS_ERR(l_ctx)) {
930 result = PTR_ERR(l_ctx);
931 nfs_direct_req_release(dreq);
932 goto out_release;
933 }
934 dreq->l_ctx = l_ctx;
935 if (!is_sync_kiocb(iocb))
936 dreq->iocb = iocb;
937 pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode);
938
939 nfs_start_io_direct(inode);
940
941 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos);
942
943 if (mapping->nrpages) {
944 invalidate_inode_pages2_range(mapping,
945 pos >> PAGE_SHIFT, end);
946 }
947
948 nfs_end_io_direct(inode);
949
950 if (requested > 0) {
951 result = nfs_direct_wait(dreq);
952 if (result > 0) {
953 requested -= result;
954 iocb->ki_pos = pos + result;
955 /* XXX: should check the generic_write_sync retval */
956 generic_write_sync(iocb, result);
957 }
958 iov_iter_revert(iter, requested);
959 } else {
960 result = requested;
961 }
962out_release:
963 nfs_direct_req_release(dreq);
964out:
965 return result;
966}
967
968/**
969 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
970 *
971 */
972int __init nfs_init_directcache(void)
973{
974 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
975 sizeof(struct nfs_direct_req),
976 0, (SLAB_RECLAIM_ACCOUNT|
977 SLAB_MEM_SPREAD),
978 NULL);
979 if (nfs_direct_cachep == NULL)
980 return -ENOMEM;
981
982 return 0;
983}
984
985/**
986 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
987 *
988 */
989void nfs_destroy_directcache(void)
990{
991 kmem_cache_destroy(nfs_direct_cachep);
992}