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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#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}
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 ssize_t count, /* bytes actually processed */
90 max_count, /* max expected count */
91 bytes_left, /* bytes left to be sent */
92 io_start, /* start of IO */
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_readpage_release(struct nfs_page *req)
396{
397 dprintk("NFS: direct read done (%s/%llu %d@%lld)\n",
398 req->wb_context->dentry->d_sb->s_id,
399 (unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)),
400 req->wb_bytes,
401 (long long)req_offset(req));
402 nfs_release_request(req);
403}
404
405static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
406{
407 unsigned long bytes = 0;
408 struct nfs_direct_req *dreq = hdr->dreq;
409
410 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
411 goto out_put;
412
413 spin_lock(&dreq->lock);
414 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
415 dreq->error = hdr->error;
416 else
417 nfs_direct_good_bytes(dreq, hdr);
418
419 spin_unlock(&dreq->lock);
420
421 while (!list_empty(&hdr->pages)) {
422 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
423 struct page *page = req->wb_page;
424
425 if (!PageCompound(page) && bytes < hdr->good_bytes)
426 set_page_dirty(page);
427 bytes += req->wb_bytes;
428 nfs_list_remove_request(req);
429 nfs_direct_readpage_release(req);
430 }
431out_put:
432 if (put_dreq(dreq))
433 nfs_direct_complete(dreq);
434 hdr->release(hdr);
435}
436
437static void nfs_read_sync_pgio_error(struct list_head *head)
438{
439 struct nfs_page *req;
440
441 while (!list_empty(head)) {
442 req = nfs_list_entry(head->next);
443 nfs_list_remove_request(req);
444 nfs_release_request(req);
445 }
446}
447
448static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
449{
450 get_dreq(hdr->dreq);
451}
452
453static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
454 .error_cleanup = nfs_read_sync_pgio_error,
455 .init_hdr = nfs_direct_pgio_init,
456 .completion = nfs_direct_read_completion,
457};
458
459/*
460 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
461 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
462 * bail and stop sending more reads. Read length accounting is
463 * handled automatically by nfs_direct_read_result(). Otherwise, if
464 * no requests have been sent, just return an error.
465 */
466
467static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
468 struct iov_iter *iter,
469 loff_t pos)
470{
471 struct nfs_pageio_descriptor desc;
472 struct inode *inode = dreq->inode;
473 ssize_t result = -EINVAL;
474 size_t requested_bytes = 0;
475 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
476
477 nfs_pageio_init_read(&desc, dreq->inode, false,
478 &nfs_direct_read_completion_ops);
479 get_dreq(dreq);
480 desc.pg_dreq = dreq;
481 inode_dio_begin(inode);
482
483 while (iov_iter_count(iter)) {
484 struct page **pagevec;
485 size_t bytes;
486 size_t pgbase;
487 unsigned npages, i;
488
489 result = iov_iter_get_pages_alloc(iter, &pagevec,
490 rsize, &pgbase);
491 if (result < 0)
492 break;
493
494 bytes = result;
495 iov_iter_advance(iter, bytes);
496 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
497 for (i = 0; i < npages; i++) {
498 struct nfs_page *req;
499 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
500 /* XXX do we need to do the eof zeroing found in async_filler? */
501 req = nfs_create_request(dreq->ctx, pagevec[i], NULL,
502 pgbase, req_len);
503 if (IS_ERR(req)) {
504 result = PTR_ERR(req);
505 break;
506 }
507 req->wb_index = pos >> PAGE_SHIFT;
508 req->wb_offset = pos & ~PAGE_MASK;
509 if (!nfs_pageio_add_request(&desc, req)) {
510 result = desc.pg_error;
511 nfs_release_request(req);
512 break;
513 }
514 pgbase = 0;
515 bytes -= req_len;
516 requested_bytes += req_len;
517 pos += req_len;
518 dreq->bytes_left -= req_len;
519 }
520 nfs_direct_release_pages(pagevec, npages);
521 kvfree(pagevec);
522 if (result < 0)
523 break;
524 }
525
526 nfs_pageio_complete(&desc);
527
528 /*
529 * If no bytes were started, return the error, and let the
530 * generic layer handle the completion.
531 */
532 if (requested_bytes == 0) {
533 inode_dio_end(inode);
534 nfs_direct_req_release(dreq);
535 return result < 0 ? result : -EIO;
536 }
537
538 if (put_dreq(dreq))
539 nfs_direct_complete(dreq);
540 return 0;
541}
542
543/**
544 * nfs_file_direct_read - file direct read operation for NFS files
545 * @iocb: target I/O control block
546 * @iter: vector of user buffers into which to read data
547 *
548 * We use this function for direct reads instead of calling
549 * generic_file_aio_read() in order to avoid gfar's check to see if
550 * the request starts before the end of the file. For that check
551 * to work, we must generate a GETATTR before each direct read, and
552 * even then there is a window between the GETATTR and the subsequent
553 * READ where the file size could change. Our preference is simply
554 * to do all reads the application wants, and the server will take
555 * care of managing the end of file boundary.
556 *
557 * This function also eliminates unnecessarily updating the file's
558 * atime locally, as the NFS server sets the file's atime, and this
559 * client must read the updated atime from the server back into its
560 * cache.
561 */
562ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
563{
564 struct file *file = iocb->ki_filp;
565 struct address_space *mapping = file->f_mapping;
566 struct inode *inode = mapping->host;
567 struct nfs_direct_req *dreq;
568 struct nfs_lock_context *l_ctx;
569 ssize_t result = -EINVAL;
570 size_t count = iov_iter_count(iter);
571 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
572
573 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
574 file, count, (long long) iocb->ki_pos);
575
576 result = 0;
577 if (!count)
578 goto out;
579
580 task_io_account_read(count);
581
582 result = -ENOMEM;
583 dreq = nfs_direct_req_alloc();
584 if (dreq == NULL)
585 goto out;
586
587 dreq->inode = inode;
588 dreq->bytes_left = dreq->max_count = count;
589 dreq->io_start = iocb->ki_pos;
590 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
591 l_ctx = nfs_get_lock_context(dreq->ctx);
592 if (IS_ERR(l_ctx)) {
593 result = PTR_ERR(l_ctx);
594 goto out_release;
595 }
596 dreq->l_ctx = l_ctx;
597 if (!is_sync_kiocb(iocb))
598 dreq->iocb = iocb;
599
600 nfs_start_io_direct(inode);
601
602 NFS_I(inode)->read_io += count;
603 result = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
604
605 nfs_end_io_direct(inode);
606
607 if (!result) {
608 result = nfs_direct_wait(dreq);
609 if (result > 0)
610 iocb->ki_pos += result;
611 }
612
613out_release:
614 nfs_direct_req_release(dreq);
615out:
616 return result;
617}
618
619static void
620nfs_direct_write_scan_commit_list(struct inode *inode,
621 struct list_head *list,
622 struct nfs_commit_info *cinfo)
623{
624 spin_lock(&cinfo->inode->i_lock);
625#ifdef CONFIG_NFS_V4_1
626 if (cinfo->ds != NULL && cinfo->ds->nwritten != 0)
627 NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo);
628#endif
629 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
630 spin_unlock(&cinfo->inode->i_lock);
631}
632
633static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
634{
635 struct nfs_pageio_descriptor desc;
636 struct nfs_page *req, *tmp;
637 LIST_HEAD(reqs);
638 struct nfs_commit_info cinfo;
639 LIST_HEAD(failed);
640 int i;
641
642 nfs_init_cinfo_from_dreq(&cinfo, dreq);
643 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
644
645 dreq->count = 0;
646 dreq->verf.committed = NFS_INVALID_STABLE_HOW;
647 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
648 for (i = 0; i < dreq->mirror_count; i++)
649 dreq->mirrors[i].count = 0;
650 get_dreq(dreq);
651
652 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
653 &nfs_direct_write_completion_ops);
654 desc.pg_dreq = dreq;
655
656 req = nfs_list_entry(reqs.next);
657 nfs_direct_setup_mirroring(dreq, &desc, req);
658 if (desc.pg_error < 0) {
659 list_splice_init(&reqs, &failed);
660 goto out_failed;
661 }
662
663 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
664 if (!nfs_pageio_add_request(&desc, req)) {
665 nfs_list_remove_request(req);
666 nfs_list_add_request(req, &failed);
667 spin_lock(&cinfo.inode->i_lock);
668 dreq->flags = 0;
669 if (desc.pg_error < 0)
670 dreq->error = desc.pg_error;
671 else
672 dreq->error = -EIO;
673 spin_unlock(&cinfo.inode->i_lock);
674 }
675 nfs_release_request(req);
676 }
677 nfs_pageio_complete(&desc);
678
679out_failed:
680 while (!list_empty(&failed)) {
681 req = nfs_list_entry(failed.next);
682 nfs_list_remove_request(req);
683 nfs_unlock_and_release_request(req);
684 }
685
686 if (put_dreq(dreq))
687 nfs_direct_write_complete(dreq);
688}
689
690static void nfs_direct_commit_complete(struct nfs_commit_data *data)
691{
692 struct nfs_direct_req *dreq = data->dreq;
693 struct nfs_commit_info cinfo;
694 struct nfs_page *req;
695 int status = data->task.tk_status;
696
697 nfs_init_cinfo_from_dreq(&cinfo, dreq);
698 if (status < 0) {
699 dprintk("NFS: %5u commit failed with error %d.\n",
700 data->task.tk_pid, status);
701 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
702 } else if (nfs_direct_cmp_commit_data_verf(dreq, data)) {
703 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
704 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
705 }
706
707 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
708 while (!list_empty(&data->pages)) {
709 req = nfs_list_entry(data->pages.next);
710 nfs_list_remove_request(req);
711 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
712 /* Note the rewrite will go through mds */
713 nfs_mark_request_commit(req, NULL, &cinfo, 0);
714 } else
715 nfs_release_request(req);
716 nfs_unlock_and_release_request(req);
717 }
718
719 if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
720 nfs_direct_write_complete(dreq);
721}
722
723static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
724 struct nfs_page *req)
725{
726 struct nfs_direct_req *dreq = cinfo->dreq;
727
728 spin_lock(&dreq->lock);
729 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
730 spin_unlock(&dreq->lock);
731 nfs_mark_request_commit(req, NULL, cinfo, 0);
732}
733
734static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
735 .completion = nfs_direct_commit_complete,
736 .resched_write = nfs_direct_resched_write,
737};
738
739static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
740{
741 int res;
742 struct nfs_commit_info cinfo;
743 LIST_HEAD(mds_list);
744
745 nfs_init_cinfo_from_dreq(&cinfo, dreq);
746 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
747 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
748 if (res < 0) /* res == -ENOMEM */
749 nfs_direct_write_reschedule(dreq);
750}
751
752static void nfs_direct_write_schedule_work(struct work_struct *work)
753{
754 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
755 int flags = dreq->flags;
756
757 dreq->flags = 0;
758 switch (flags) {
759 case NFS_ODIRECT_DO_COMMIT:
760 nfs_direct_commit_schedule(dreq);
761 break;
762 case NFS_ODIRECT_RESCHED_WRITES:
763 nfs_direct_write_reschedule(dreq);
764 break;
765 default:
766 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
767 nfs_direct_complete(dreq);
768 }
769}
770
771static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
772{
773 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
774}
775
776static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
777{
778 struct nfs_direct_req *dreq = hdr->dreq;
779 struct nfs_commit_info cinfo;
780 bool request_commit = false;
781 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
782
783 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
784 goto out_put;
785
786 nfs_init_cinfo_from_dreq(&cinfo, dreq);
787
788 spin_lock(&dreq->lock);
789
790 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
791 dreq->flags = 0;
792 dreq->error = hdr->error;
793 }
794 if (dreq->error == 0) {
795 nfs_direct_good_bytes(dreq, hdr);
796 if (nfs_write_need_commit(hdr)) {
797 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
798 request_commit = true;
799 else if (dreq->flags == 0) {
800 nfs_direct_set_hdr_verf(dreq, hdr);
801 request_commit = true;
802 dreq->flags = NFS_ODIRECT_DO_COMMIT;
803 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
804 request_commit = true;
805 if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr))
806 dreq->flags =
807 NFS_ODIRECT_RESCHED_WRITES;
808 }
809 }
810 }
811 spin_unlock(&dreq->lock);
812
813 while (!list_empty(&hdr->pages)) {
814
815 req = nfs_list_entry(hdr->pages.next);
816 nfs_list_remove_request(req);
817 if (request_commit) {
818 kref_get(&req->wb_kref);
819 nfs_mark_request_commit(req, hdr->lseg, &cinfo,
820 hdr->ds_commit_idx);
821 }
822 nfs_unlock_and_release_request(req);
823 }
824
825out_put:
826 if (put_dreq(dreq))
827 nfs_direct_write_complete(dreq);
828 hdr->release(hdr);
829}
830
831static void nfs_write_sync_pgio_error(struct list_head *head)
832{
833 struct nfs_page *req;
834
835 while (!list_empty(head)) {
836 req = nfs_list_entry(head->next);
837 nfs_list_remove_request(req);
838 nfs_unlock_and_release_request(req);
839 }
840}
841
842static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
843{
844 struct nfs_direct_req *dreq = hdr->dreq;
845
846 spin_lock(&dreq->lock);
847 if (dreq->error == 0) {
848 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
849 /* fake unstable write to let common nfs resend pages */
850 hdr->verf.committed = NFS_UNSTABLE;
851 hdr->good_bytes = hdr->args.count;
852 }
853 spin_unlock(&dreq->lock);
854}
855
856static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
857 .error_cleanup = nfs_write_sync_pgio_error,
858 .init_hdr = nfs_direct_pgio_init,
859 .completion = nfs_direct_write_completion,
860 .reschedule_io = nfs_direct_write_reschedule_io,
861};
862
863
864/*
865 * NB: Return the value of the first error return code. Subsequent
866 * errors after the first one are ignored.
867 */
868/*
869 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
870 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
871 * bail and stop sending more writes. Write length accounting is
872 * handled automatically by nfs_direct_write_result(). Otherwise, if
873 * no requests have been sent, just return an error.
874 */
875static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
876 struct iov_iter *iter,
877 loff_t pos)
878{
879 struct nfs_pageio_descriptor desc;
880 struct inode *inode = dreq->inode;
881 ssize_t result = 0;
882 size_t requested_bytes = 0;
883 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
884
885 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false,
886 &nfs_direct_write_completion_ops);
887 desc.pg_dreq = dreq;
888 get_dreq(dreq);
889 inode_dio_begin(inode);
890
891 NFS_I(inode)->write_io += iov_iter_count(iter);
892 while (iov_iter_count(iter)) {
893 struct page **pagevec;
894 size_t bytes;
895 size_t pgbase;
896 unsigned npages, i;
897
898 result = iov_iter_get_pages_alloc(iter, &pagevec,
899 wsize, &pgbase);
900 if (result < 0)
901 break;
902
903 bytes = result;
904 iov_iter_advance(iter, bytes);
905 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
906 for (i = 0; i < npages; i++) {
907 struct nfs_page *req;
908 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
909
910 req = nfs_create_request(dreq->ctx, pagevec[i], NULL,
911 pgbase, req_len);
912 if (IS_ERR(req)) {
913 result = PTR_ERR(req);
914 break;
915 }
916
917 nfs_direct_setup_mirroring(dreq, &desc, req);
918 if (desc.pg_error < 0) {
919 nfs_free_request(req);
920 result = desc.pg_error;
921 break;
922 }
923
924 nfs_lock_request(req);
925 req->wb_index = pos >> PAGE_SHIFT;
926 req->wb_offset = pos & ~PAGE_MASK;
927 if (!nfs_pageio_add_request(&desc, req)) {
928 result = desc.pg_error;
929 nfs_unlock_and_release_request(req);
930 break;
931 }
932 pgbase = 0;
933 bytes -= req_len;
934 requested_bytes += req_len;
935 pos += req_len;
936 dreq->bytes_left -= req_len;
937 }
938 nfs_direct_release_pages(pagevec, npages);
939 kvfree(pagevec);
940 if (result < 0)
941 break;
942 }
943 nfs_pageio_complete(&desc);
944
945 /*
946 * If no bytes were started, return the error, and let the
947 * generic layer handle the completion.
948 */
949 if (requested_bytes == 0) {
950 inode_dio_end(inode);
951 nfs_direct_req_release(dreq);
952 return result < 0 ? result : -EIO;
953 }
954
955 if (put_dreq(dreq))
956 nfs_direct_write_complete(dreq);
957 return 0;
958}
959
960/**
961 * nfs_file_direct_write - file direct write operation for NFS files
962 * @iocb: target I/O control block
963 * @iter: vector of user buffers from which to write data
964 *
965 * We use this function for direct writes instead of calling
966 * generic_file_aio_write() in order to avoid taking the inode
967 * semaphore and updating the i_size. The NFS server will set
968 * the new i_size and this client must read the updated size
969 * back into its cache. We let the server do generic write
970 * parameter checking and report problems.
971 *
972 * We eliminate local atime updates, see direct read above.
973 *
974 * We avoid unnecessary page cache invalidations for normal cached
975 * readers of this file.
976 *
977 * Note that O_APPEND is not supported for NFS direct writes, as there
978 * is no atomic O_APPEND write facility in the NFS protocol.
979 */
980ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
981{
982 ssize_t result = -EINVAL;
983 size_t count;
984 struct file *file = iocb->ki_filp;
985 struct address_space *mapping = file->f_mapping;
986 struct inode *inode = mapping->host;
987 struct nfs_direct_req *dreq;
988 struct nfs_lock_context *l_ctx;
989 loff_t pos, end;
990
991 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
992 file, iov_iter_count(iter), (long long) iocb->ki_pos);
993
994 result = generic_write_checks(iocb, iter);
995 if (result <= 0)
996 return result;
997 count = result;
998 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
999
1000 pos = iocb->ki_pos;
1001 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
1002
1003 task_io_account_write(count);
1004
1005 result = -ENOMEM;
1006 dreq = nfs_direct_req_alloc();
1007 if (!dreq)
1008 goto out;
1009
1010 dreq->inode = inode;
1011 dreq->bytes_left = dreq->max_count = count;
1012 dreq->io_start = pos;
1013 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
1014 l_ctx = nfs_get_lock_context(dreq->ctx);
1015 if (IS_ERR(l_ctx)) {
1016 result = PTR_ERR(l_ctx);
1017 goto out_release;
1018 }
1019 dreq->l_ctx = l_ctx;
1020 if (!is_sync_kiocb(iocb))
1021 dreq->iocb = iocb;
1022
1023 nfs_start_io_direct(inode);
1024
1025 result = nfs_direct_write_schedule_iovec(dreq, iter, pos);
1026
1027 if (mapping->nrpages) {
1028 invalidate_inode_pages2_range(mapping,
1029 pos >> PAGE_SHIFT, end);
1030 }
1031
1032 nfs_end_io_direct(inode);
1033
1034 if (!result) {
1035 result = nfs_direct_wait(dreq);
1036 if (result > 0) {
1037 iocb->ki_pos = pos + result;
1038 /* XXX: should check the generic_write_sync retval */
1039 generic_write_sync(iocb, result);
1040 }
1041 }
1042out_release:
1043 nfs_direct_req_release(dreq);
1044out:
1045 return result;
1046}
1047
1048/**
1049 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1050 *
1051 */
1052int __init nfs_init_directcache(void)
1053{
1054 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1055 sizeof(struct nfs_direct_req),
1056 0, (SLAB_RECLAIM_ACCOUNT|
1057 SLAB_MEM_SPREAD),
1058 NULL);
1059 if (nfs_direct_cachep == NULL)
1060 return -ENOMEM;
1061
1062 return 0;
1063}
1064
1065/**
1066 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1067 *
1068 */
1069void nfs_destroy_directcache(void)
1070{
1071 kmem_cache_destroy(nfs_direct_cachep);
1072}