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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 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}
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 <asm/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_req {
70 struct kref kref; /* release manager */
71
72 /* I/O parameters */
73 struct nfs_open_context *ctx; /* file open context info */
74 struct nfs_lock_context *l_ctx; /* Lock context info */
75 struct kiocb * iocb; /* controlling i/o request */
76 struct inode * inode; /* target file of i/o */
77
78 /* completion state */
79 atomic_t io_count; /* i/os we're waiting for */
80 spinlock_t lock; /* protect completion state */
81 ssize_t count, /* bytes actually processed */
82 bytes_left, /* bytes left to be sent */
83 error; /* any reported error */
84 struct completion completion; /* wait for i/o completion */
85
86 /* commit state */
87 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
88 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
89 struct work_struct work;
90 int flags;
91#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
92#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
93 struct nfs_writeverf verf; /* unstable write verifier */
94};
95
96static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
97static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
98static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
99static void nfs_direct_write_schedule_work(struct work_struct *work);
100
101static inline void get_dreq(struct nfs_direct_req *dreq)
102{
103 atomic_inc(&dreq->io_count);
104}
105
106static inline int put_dreq(struct nfs_direct_req *dreq)
107{
108 return atomic_dec_and_test(&dreq->io_count);
109}
110
111/**
112 * nfs_direct_IO - NFS address space operation for direct I/O
113 * @rw: direction (read or write)
114 * @iocb: target I/O control block
115 * @iov: array of vectors that define I/O buffer
116 * @pos: offset in file to begin the operation
117 * @nr_segs: size of iovec array
118 *
119 * The presence of this routine in the address space ops vector means
120 * the NFS client supports direct I/O. However, for most direct IO, we
121 * shunt off direct read and write requests before the VFS gets them,
122 * so this method is only ever called for swap.
123 */
124ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
125{
126#ifndef CONFIG_NFS_SWAP
127 dprintk("NFS: nfs_direct_IO (%pD) off/no(%Ld/%lu) EINVAL\n",
128 iocb->ki_filp, (long long) pos, nr_segs);
129
130 return -EINVAL;
131#else
132 VM_BUG_ON(iocb->ki_nbytes != PAGE_SIZE);
133
134 if (rw == READ || rw == KERNEL_READ)
135 return nfs_file_direct_read(iocb, iov, nr_segs, pos,
136 rw == READ ? true : false);
137 return nfs_file_direct_write(iocb, iov, nr_segs, pos,
138 rw == WRITE ? true : false);
139#endif /* CONFIG_NFS_SWAP */
140}
141
142static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
143{
144 unsigned int i;
145 for (i = 0; i < npages; i++)
146 page_cache_release(pages[i]);
147}
148
149void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
150 struct nfs_direct_req *dreq)
151{
152 cinfo->lock = &dreq->lock;
153 cinfo->mds = &dreq->mds_cinfo;
154 cinfo->ds = &dreq->ds_cinfo;
155 cinfo->dreq = dreq;
156 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
157}
158
159static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
160{
161 struct nfs_direct_req *dreq;
162
163 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
164 if (!dreq)
165 return NULL;
166
167 kref_init(&dreq->kref);
168 kref_get(&dreq->kref);
169 init_completion(&dreq->completion);
170 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
171 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
172 spin_lock_init(&dreq->lock);
173
174 return dreq;
175}
176
177static void nfs_direct_req_free(struct kref *kref)
178{
179 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
180
181 if (dreq->l_ctx != NULL)
182 nfs_put_lock_context(dreq->l_ctx);
183 if (dreq->ctx != NULL)
184 put_nfs_open_context(dreq->ctx);
185 kmem_cache_free(nfs_direct_cachep, dreq);
186}
187
188static void nfs_direct_req_release(struct nfs_direct_req *dreq)
189{
190 kref_put(&dreq->kref, nfs_direct_req_free);
191}
192
193ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
194{
195 return dreq->bytes_left;
196}
197EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
198
199/*
200 * Collects and returns the final error value/byte-count.
201 */
202static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
203{
204 ssize_t result = -EIOCBQUEUED;
205
206 /* Async requests don't wait here */
207 if (dreq->iocb)
208 goto out;
209
210 result = wait_for_completion_killable(&dreq->completion);
211
212 if (!result)
213 result = dreq->error;
214 if (!result)
215 result = dreq->count;
216
217out:
218 return (ssize_t) result;
219}
220
221/*
222 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
223 * the iocb is still valid here if this is a synchronous request.
224 */
225static void nfs_direct_complete(struct nfs_direct_req *dreq, bool write)
226{
227 struct inode *inode = dreq->inode;
228
229 if (dreq->iocb && write) {
230 loff_t pos = dreq->iocb->ki_pos + dreq->count;
231
232 spin_lock(&inode->i_lock);
233 if (i_size_read(inode) < pos)
234 i_size_write(inode, pos);
235 spin_unlock(&inode->i_lock);
236 }
237
238 if (write)
239 nfs_zap_mapping(inode, inode->i_mapping);
240
241 inode_dio_done(inode);
242
243 if (dreq->iocb) {
244 long res = (long) dreq->error;
245 if (!res)
246 res = (long) dreq->count;
247 aio_complete(dreq->iocb, res, 0);
248 }
249
250 complete_all(&dreq->completion);
251
252 nfs_direct_req_release(dreq);
253}
254
255static void nfs_direct_readpage_release(struct nfs_page *req)
256{
257 dprintk("NFS: direct read done (%s/%llu %d@%lld)\n",
258 req->wb_context->dentry->d_inode->i_sb->s_id,
259 (unsigned long long)NFS_FILEID(req->wb_context->dentry->d_inode),
260 req->wb_bytes,
261 (long long)req_offset(req));
262 nfs_release_request(req);
263}
264
265static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
266{
267 unsigned long bytes = 0;
268 struct nfs_direct_req *dreq = hdr->dreq;
269
270 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
271 goto out_put;
272
273 spin_lock(&dreq->lock);
274 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
275 dreq->error = hdr->error;
276 else
277 dreq->count += hdr->good_bytes;
278 spin_unlock(&dreq->lock);
279
280 while (!list_empty(&hdr->pages)) {
281 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
282 struct page *page = req->wb_page;
283
284 if (!PageCompound(page) && bytes < hdr->good_bytes)
285 set_page_dirty(page);
286 bytes += req->wb_bytes;
287 nfs_list_remove_request(req);
288 nfs_direct_readpage_release(req);
289 }
290out_put:
291 if (put_dreq(dreq))
292 nfs_direct_complete(dreq, false);
293 hdr->release(hdr);
294}
295
296static void nfs_read_sync_pgio_error(struct list_head *head)
297{
298 struct nfs_page *req;
299
300 while (!list_empty(head)) {
301 req = nfs_list_entry(head->next);
302 nfs_list_remove_request(req);
303 nfs_release_request(req);
304 }
305}
306
307static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
308{
309 get_dreq(hdr->dreq);
310}
311
312static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
313 .error_cleanup = nfs_read_sync_pgio_error,
314 .init_hdr = nfs_direct_pgio_init,
315 .completion = nfs_direct_read_completion,
316};
317
318/*
319 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
320 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
321 * bail and stop sending more reads. Read length accounting is
322 * handled automatically by nfs_direct_read_result(). Otherwise, if
323 * no requests have been sent, just return an error.
324 */
325static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
326 const struct iovec *iov,
327 loff_t pos, bool uio)
328{
329 struct nfs_direct_req *dreq = desc->pg_dreq;
330 struct nfs_open_context *ctx = dreq->ctx;
331 struct inode *inode = ctx->dentry->d_inode;
332 unsigned long user_addr = (unsigned long)iov->iov_base;
333 size_t count = iov->iov_len;
334 size_t rsize = NFS_SERVER(inode)->rsize;
335 unsigned int pgbase;
336 int result;
337 ssize_t started = 0;
338 struct page **pagevec = NULL;
339 unsigned int npages;
340
341 do {
342 size_t bytes;
343 int i;
344
345 pgbase = user_addr & ~PAGE_MASK;
346 bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
347
348 result = -ENOMEM;
349 npages = nfs_page_array_len(pgbase, bytes);
350 if (!pagevec)
351 pagevec = kmalloc(npages * sizeof(struct page *),
352 GFP_KERNEL);
353 if (!pagevec)
354 break;
355 if (uio) {
356 down_read(¤t->mm->mmap_sem);
357 result = get_user_pages(current, current->mm, user_addr,
358 npages, 1, 0, pagevec, NULL);
359 up_read(¤t->mm->mmap_sem);
360 if (result < 0)
361 break;
362 } else {
363 WARN_ON(npages != 1);
364 result = get_kernel_page(user_addr, 1, pagevec);
365 if (WARN_ON(result != 1))
366 break;
367 }
368
369 if ((unsigned)result < npages) {
370 bytes = result * PAGE_SIZE;
371 if (bytes <= pgbase) {
372 nfs_direct_release_pages(pagevec, result);
373 break;
374 }
375 bytes -= pgbase;
376 npages = result;
377 }
378
379 for (i = 0; i < npages; i++) {
380 struct nfs_page *req;
381 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
382 /* XXX do we need to do the eof zeroing found in async_filler? */
383 req = nfs_create_request(dreq->ctx, dreq->inode,
384 pagevec[i],
385 pgbase, req_len);
386 if (IS_ERR(req)) {
387 result = PTR_ERR(req);
388 break;
389 }
390 req->wb_index = pos >> PAGE_SHIFT;
391 req->wb_offset = pos & ~PAGE_MASK;
392 if (!nfs_pageio_add_request(desc, req)) {
393 result = desc->pg_error;
394 nfs_release_request(req);
395 break;
396 }
397 pgbase = 0;
398 bytes -= req_len;
399 started += req_len;
400 user_addr += req_len;
401 pos += req_len;
402 count -= req_len;
403 dreq->bytes_left -= req_len;
404 }
405 /* The nfs_page now hold references to these pages */
406 nfs_direct_release_pages(pagevec, npages);
407 } while (count != 0 && result >= 0);
408
409 kfree(pagevec);
410
411 if (started)
412 return started;
413 return result < 0 ? (ssize_t) result : -EFAULT;
414}
415
416static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
417 const struct iovec *iov,
418 unsigned long nr_segs,
419 loff_t pos, bool uio)
420{
421 struct nfs_pageio_descriptor desc;
422 struct inode *inode = dreq->inode;
423 ssize_t result = -EINVAL;
424 size_t requested_bytes = 0;
425 unsigned long seg;
426
427 NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
428 &nfs_direct_read_completion_ops);
429 get_dreq(dreq);
430 desc.pg_dreq = dreq;
431 atomic_inc(&inode->i_dio_count);
432
433 for (seg = 0; seg < nr_segs; seg++) {
434 const struct iovec *vec = &iov[seg];
435 result = nfs_direct_read_schedule_segment(&desc, vec, pos, uio);
436 if (result < 0)
437 break;
438 requested_bytes += result;
439 if ((size_t)result < vec->iov_len)
440 break;
441 pos += vec->iov_len;
442 }
443
444 nfs_pageio_complete(&desc);
445
446 /*
447 * If no bytes were started, return the error, and let the
448 * generic layer handle the completion.
449 */
450 if (requested_bytes == 0) {
451 inode_dio_done(inode);
452 nfs_direct_req_release(dreq);
453 return result < 0 ? result : -EIO;
454 }
455
456 if (put_dreq(dreq))
457 nfs_direct_complete(dreq, false);
458 return 0;
459}
460
461/**
462 * nfs_file_direct_read - file direct read operation for NFS files
463 * @iocb: target I/O control block
464 * @iov: vector of user buffers into which to read data
465 * @nr_segs: size of iov vector
466 * @pos: byte offset in file where reading starts
467 *
468 * We use this function for direct reads instead of calling
469 * generic_file_aio_read() in order to avoid gfar's check to see if
470 * the request starts before the end of the file. For that check
471 * to work, we must generate a GETATTR before each direct read, and
472 * even then there is a window between the GETATTR and the subsequent
473 * READ where the file size could change. Our preference is simply
474 * to do all reads the application wants, and the server will take
475 * care of managing the end of file boundary.
476 *
477 * This function also eliminates unnecessarily updating the file's
478 * atime locally, as the NFS server sets the file's atime, and this
479 * client must read the updated atime from the server back into its
480 * cache.
481 */
482ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
483 unsigned long nr_segs, loff_t pos, bool uio)
484{
485 struct file *file = iocb->ki_filp;
486 struct address_space *mapping = file->f_mapping;
487 struct inode *inode = mapping->host;
488 struct nfs_direct_req *dreq;
489 struct nfs_lock_context *l_ctx;
490 ssize_t result = -EINVAL;
491 size_t count;
492
493 count = iov_length(iov, nr_segs);
494 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
495
496 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
497 file, count, (long long) pos);
498
499 result = 0;
500 if (!count)
501 goto out;
502
503 mutex_lock(&inode->i_mutex);
504 result = nfs_sync_mapping(mapping);
505 if (result)
506 goto out_unlock;
507
508 task_io_account_read(count);
509
510 result = -ENOMEM;
511 dreq = nfs_direct_req_alloc();
512 if (dreq == NULL)
513 goto out_unlock;
514
515 dreq->inode = inode;
516 dreq->bytes_left = iov_length(iov, nr_segs);
517 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
518 l_ctx = nfs_get_lock_context(dreq->ctx);
519 if (IS_ERR(l_ctx)) {
520 result = PTR_ERR(l_ctx);
521 goto out_release;
522 }
523 dreq->l_ctx = l_ctx;
524 if (!is_sync_kiocb(iocb))
525 dreq->iocb = iocb;
526
527 NFS_I(inode)->read_io += iov_length(iov, nr_segs);
528 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
529
530 mutex_unlock(&inode->i_mutex);
531
532 if (!result) {
533 result = nfs_direct_wait(dreq);
534 if (result > 0)
535 iocb->ki_pos = pos + result;
536 }
537
538 nfs_direct_req_release(dreq);
539 return result;
540
541out_release:
542 nfs_direct_req_release(dreq);
543out_unlock:
544 mutex_unlock(&inode->i_mutex);
545out:
546 return result;
547}
548
549#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
550static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
551{
552 struct nfs_pageio_descriptor desc;
553 struct nfs_page *req, *tmp;
554 LIST_HEAD(reqs);
555 struct nfs_commit_info cinfo;
556 LIST_HEAD(failed);
557
558 nfs_init_cinfo_from_dreq(&cinfo, dreq);
559 pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
560 spin_lock(cinfo.lock);
561 nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
562 spin_unlock(cinfo.lock);
563
564 dreq->count = 0;
565 get_dreq(dreq);
566
567 NFS_PROTO(dreq->inode)->write_pageio_init(&desc, dreq->inode, FLUSH_STABLE,
568 &nfs_direct_write_completion_ops);
569 desc.pg_dreq = dreq;
570
571 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
572 if (!nfs_pageio_add_request(&desc, req)) {
573 nfs_list_remove_request(req);
574 nfs_list_add_request(req, &failed);
575 spin_lock(cinfo.lock);
576 dreq->flags = 0;
577 dreq->error = -EIO;
578 spin_unlock(cinfo.lock);
579 }
580 nfs_release_request(req);
581 }
582 nfs_pageio_complete(&desc);
583
584 while (!list_empty(&failed)) {
585 req = nfs_list_entry(failed.next);
586 nfs_list_remove_request(req);
587 nfs_unlock_and_release_request(req);
588 }
589
590 if (put_dreq(dreq))
591 nfs_direct_write_complete(dreq, dreq->inode);
592}
593
594static void nfs_direct_commit_complete(struct nfs_commit_data *data)
595{
596 struct nfs_direct_req *dreq = data->dreq;
597 struct nfs_commit_info cinfo;
598 struct nfs_page *req;
599 int status = data->task.tk_status;
600
601 nfs_init_cinfo_from_dreq(&cinfo, dreq);
602 if (status < 0) {
603 dprintk("NFS: %5u commit failed with error %d.\n",
604 data->task.tk_pid, status);
605 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
606 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
607 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
608 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
609 }
610
611 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
612 while (!list_empty(&data->pages)) {
613 req = nfs_list_entry(data->pages.next);
614 nfs_list_remove_request(req);
615 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
616 /* Note the rewrite will go through mds */
617 nfs_mark_request_commit(req, NULL, &cinfo);
618 } else
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, data->inode);
625}
626
627static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
628{
629 /* There is no lock to clear */
630}
631
632static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
633 .completion = nfs_direct_commit_complete,
634 .error_cleanup = nfs_direct_error_cleanup,
635};
636
637static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
638{
639 int res;
640 struct nfs_commit_info cinfo;
641 LIST_HEAD(mds_list);
642
643 nfs_init_cinfo_from_dreq(&cinfo, dreq);
644 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
645 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
646 if (res < 0) /* res == -ENOMEM */
647 nfs_direct_write_reschedule(dreq);
648}
649
650static void nfs_direct_write_schedule_work(struct work_struct *work)
651{
652 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
653 int flags = dreq->flags;
654
655 dreq->flags = 0;
656 switch (flags) {
657 case NFS_ODIRECT_DO_COMMIT:
658 nfs_direct_commit_schedule(dreq);
659 break;
660 case NFS_ODIRECT_RESCHED_WRITES:
661 nfs_direct_write_reschedule(dreq);
662 break;
663 default:
664 nfs_direct_complete(dreq, true);
665 }
666}
667
668static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
669{
670 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
671}
672
673#else
674static void nfs_direct_write_schedule_work(struct work_struct *work)
675{
676}
677
678static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
679{
680 nfs_direct_complete(dreq, true);
681}
682#endif
683
684/*
685 * NB: Return the value of the first error return code. Subsequent
686 * errors after the first one are ignored.
687 */
688/*
689 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
690 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
691 * bail and stop sending more writes. Write length accounting is
692 * handled automatically by nfs_direct_write_result(). Otherwise, if
693 * no requests have been sent, just return an error.
694 */
695static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
696 const struct iovec *iov,
697 loff_t pos, bool uio)
698{
699 struct nfs_direct_req *dreq = desc->pg_dreq;
700 struct nfs_open_context *ctx = dreq->ctx;
701 struct inode *inode = ctx->dentry->d_inode;
702 unsigned long user_addr = (unsigned long)iov->iov_base;
703 size_t count = iov->iov_len;
704 size_t wsize = NFS_SERVER(inode)->wsize;
705 unsigned int pgbase;
706 int result;
707 ssize_t started = 0;
708 struct page **pagevec = NULL;
709 unsigned int npages;
710
711 do {
712 size_t bytes;
713 int i;
714
715 pgbase = user_addr & ~PAGE_MASK;
716 bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
717
718 result = -ENOMEM;
719 npages = nfs_page_array_len(pgbase, bytes);
720 if (!pagevec)
721 pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
722 if (!pagevec)
723 break;
724
725 if (uio) {
726 down_read(¤t->mm->mmap_sem);
727 result = get_user_pages(current, current->mm, user_addr,
728 npages, 0, 0, pagevec, NULL);
729 up_read(¤t->mm->mmap_sem);
730 if (result < 0)
731 break;
732 } else {
733 WARN_ON(npages != 1);
734 result = get_kernel_page(user_addr, 0, pagevec);
735 if (WARN_ON(result != 1))
736 break;
737 }
738
739 if ((unsigned)result < npages) {
740 bytes = result * PAGE_SIZE;
741 if (bytes <= pgbase) {
742 nfs_direct_release_pages(pagevec, result);
743 break;
744 }
745 bytes -= pgbase;
746 npages = result;
747 }
748
749 for (i = 0; i < npages; i++) {
750 struct nfs_page *req;
751 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
752
753 req = nfs_create_request(dreq->ctx, dreq->inode,
754 pagevec[i],
755 pgbase, req_len);
756 if (IS_ERR(req)) {
757 result = PTR_ERR(req);
758 break;
759 }
760 nfs_lock_request(req);
761 req->wb_index = pos >> PAGE_SHIFT;
762 req->wb_offset = pos & ~PAGE_MASK;
763 if (!nfs_pageio_add_request(desc, req)) {
764 result = desc->pg_error;
765 nfs_unlock_and_release_request(req);
766 break;
767 }
768 pgbase = 0;
769 bytes -= req_len;
770 started += req_len;
771 user_addr += req_len;
772 pos += req_len;
773 count -= req_len;
774 dreq->bytes_left -= req_len;
775 }
776 /* The nfs_page now hold references to these pages */
777 nfs_direct_release_pages(pagevec, npages);
778 } while (count != 0 && result >= 0);
779
780 kfree(pagevec);
781
782 if (started)
783 return started;
784 return result < 0 ? (ssize_t) result : -EFAULT;
785}
786
787static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
788{
789 struct nfs_direct_req *dreq = hdr->dreq;
790 struct nfs_commit_info cinfo;
791 int bit = -1;
792 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
793
794 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
795 goto out_put;
796
797 nfs_init_cinfo_from_dreq(&cinfo, dreq);
798
799 spin_lock(&dreq->lock);
800
801 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
802 dreq->flags = 0;
803 dreq->error = hdr->error;
804 }
805 if (dreq->error != 0)
806 bit = NFS_IOHDR_ERROR;
807 else {
808 dreq->count += hdr->good_bytes;
809 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
810 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
811 bit = NFS_IOHDR_NEED_RESCHED;
812 } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
813 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
814 bit = NFS_IOHDR_NEED_RESCHED;
815 else if (dreq->flags == 0) {
816 memcpy(&dreq->verf, hdr->verf,
817 sizeof(dreq->verf));
818 bit = NFS_IOHDR_NEED_COMMIT;
819 dreq->flags = NFS_ODIRECT_DO_COMMIT;
820 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
821 if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
822 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
823 bit = NFS_IOHDR_NEED_RESCHED;
824 } else
825 bit = NFS_IOHDR_NEED_COMMIT;
826 }
827 }
828 }
829 spin_unlock(&dreq->lock);
830
831 while (!list_empty(&hdr->pages)) {
832 req = nfs_list_entry(hdr->pages.next);
833 nfs_list_remove_request(req);
834 switch (bit) {
835 case NFS_IOHDR_NEED_RESCHED:
836 case NFS_IOHDR_NEED_COMMIT:
837 kref_get(&req->wb_kref);
838 nfs_mark_request_commit(req, hdr->lseg, &cinfo);
839 }
840 nfs_unlock_and_release_request(req);
841 }
842
843out_put:
844 if (put_dreq(dreq))
845 nfs_direct_write_complete(dreq, hdr->inode);
846 hdr->release(hdr);
847}
848
849static void nfs_write_sync_pgio_error(struct list_head *head)
850{
851 struct nfs_page *req;
852
853 while (!list_empty(head)) {
854 req = nfs_list_entry(head->next);
855 nfs_list_remove_request(req);
856 nfs_unlock_and_release_request(req);
857 }
858}
859
860static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
861 .error_cleanup = nfs_write_sync_pgio_error,
862 .init_hdr = nfs_direct_pgio_init,
863 .completion = nfs_direct_write_completion,
864};
865
866static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
867 const struct iovec *iov,
868 unsigned long nr_segs,
869 loff_t pos, bool uio)
870{
871 struct nfs_pageio_descriptor desc;
872 struct inode *inode = dreq->inode;
873 ssize_t result = 0;
874 size_t requested_bytes = 0;
875 unsigned long seg;
876
877 NFS_PROTO(inode)->write_pageio_init(&desc, inode, FLUSH_COND_STABLE,
878 &nfs_direct_write_completion_ops);
879 desc.pg_dreq = dreq;
880 get_dreq(dreq);
881 atomic_inc(&inode->i_dio_count);
882
883 NFS_I(dreq->inode)->write_io += iov_length(iov, nr_segs);
884 for (seg = 0; seg < nr_segs; seg++) {
885 const struct iovec *vec = &iov[seg];
886 result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
887 if (result < 0)
888 break;
889 requested_bytes += result;
890 if ((size_t)result < vec->iov_len)
891 break;
892 pos += vec->iov_len;
893 }
894 nfs_pageio_complete(&desc);
895
896 /*
897 * If no bytes were started, return the error, and let the
898 * generic layer handle the completion.
899 */
900 if (requested_bytes == 0) {
901 inode_dio_done(inode);
902 nfs_direct_req_release(dreq);
903 return result < 0 ? result : -EIO;
904 }
905
906 if (put_dreq(dreq))
907 nfs_direct_write_complete(dreq, dreq->inode);
908 return 0;
909}
910
911/**
912 * nfs_file_direct_write - file direct write operation for NFS files
913 * @iocb: target I/O control block
914 * @iov: vector of user buffers from which to write data
915 * @nr_segs: size of iov vector
916 * @pos: byte offset in file where writing starts
917 *
918 * We use this function for direct writes instead of calling
919 * generic_file_aio_write() in order to avoid taking the inode
920 * semaphore and updating the i_size. The NFS server will set
921 * the new i_size and this client must read the updated size
922 * back into its cache. We let the server do generic write
923 * parameter checking and report problems.
924 *
925 * We eliminate local atime updates, see direct read above.
926 *
927 * We avoid unnecessary page cache invalidations for normal cached
928 * readers of this file.
929 *
930 * Note that O_APPEND is not supported for NFS direct writes, as there
931 * is no atomic O_APPEND write facility in the NFS protocol.
932 */
933ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
934 unsigned long nr_segs, loff_t pos, bool uio)
935{
936 ssize_t result = -EINVAL;
937 struct file *file = iocb->ki_filp;
938 struct address_space *mapping = file->f_mapping;
939 struct inode *inode = mapping->host;
940 struct nfs_direct_req *dreq;
941 struct nfs_lock_context *l_ctx;
942 loff_t end;
943 size_t count;
944
945 count = iov_length(iov, nr_segs);
946 end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
947
948 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
949
950 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
951 file, count, (long long) pos);
952
953 result = generic_write_checks(file, &pos, &count, 0);
954 if (result)
955 goto out;
956
957 result = -EINVAL;
958 if ((ssize_t) count < 0)
959 goto out;
960 result = 0;
961 if (!count)
962 goto out;
963
964 mutex_lock(&inode->i_mutex);
965
966 result = nfs_sync_mapping(mapping);
967 if (result)
968 goto out_unlock;
969
970 if (mapping->nrpages) {
971 result = invalidate_inode_pages2_range(mapping,
972 pos >> PAGE_CACHE_SHIFT, end);
973 if (result)
974 goto out_unlock;
975 }
976
977 task_io_account_write(count);
978
979 result = -ENOMEM;
980 dreq = nfs_direct_req_alloc();
981 if (!dreq)
982 goto out_unlock;
983
984 dreq->inode = inode;
985 dreq->bytes_left = count;
986 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
987 l_ctx = nfs_get_lock_context(dreq->ctx);
988 if (IS_ERR(l_ctx)) {
989 result = PTR_ERR(l_ctx);
990 goto out_release;
991 }
992 dreq->l_ctx = l_ctx;
993 if (!is_sync_kiocb(iocb))
994 dreq->iocb = iocb;
995
996 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, uio);
997
998 if (mapping->nrpages) {
999 invalidate_inode_pages2_range(mapping,
1000 pos >> PAGE_CACHE_SHIFT, end);
1001 }
1002
1003 mutex_unlock(&inode->i_mutex);
1004
1005 if (!result) {
1006 result = nfs_direct_wait(dreq);
1007 if (result > 0) {
1008 struct inode *inode = mapping->host;
1009
1010 iocb->ki_pos = pos + result;
1011 spin_lock(&inode->i_lock);
1012 if (i_size_read(inode) < iocb->ki_pos)
1013 i_size_write(inode, iocb->ki_pos);
1014 spin_unlock(&inode->i_lock);
1015 }
1016 }
1017 nfs_direct_req_release(dreq);
1018 return result;
1019
1020out_release:
1021 nfs_direct_req_release(dreq);
1022out_unlock:
1023 mutex_unlock(&inode->i_mutex);
1024out:
1025 return result;
1026}
1027
1028/**
1029 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1030 *
1031 */
1032int __init nfs_init_directcache(void)
1033{
1034 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1035 sizeof(struct nfs_direct_req),
1036 0, (SLAB_RECLAIM_ACCOUNT|
1037 SLAB_MEM_SPREAD),
1038 NULL);
1039 if (nfs_direct_cachep == NULL)
1040 return -ENOMEM;
1041
1042 return 0;
1043}
1044
1045/**
1046 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1047 *
1048 */
1049void nfs_destroy_directcache(void)
1050{
1051 kmem_cache_destroy(nfs_direct_cachep);
1052}