1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/fs/nfs/direct.c
4 *
5 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
6 *
7 * High-performance uncached I/O for the Linux NFS client
8 *
9 * There are important applications whose performance or correctness
10 * depends on uncached access to file data. Database clusters
11 * (multiple copies of the same instance running on separate hosts)
12 * implement their own cache coherency protocol that subsumes file
13 * system cache protocols. Applications that process datasets
14 * considerably larger than the client's memory do not always benefit
15 * from a local cache. A streaming video server, for instance, has no
16 * need to cache the contents of a file.
17 *
18 * When an application requests uncached I/O, all read and write requests
19 * are made directly to the server; data stored or fetched via these
20 * requests is not cached in the Linux page cache. The client does not
21 * correct unaligned requests from applications. All requested bytes are
22 * held on permanent storage before a direct write system call returns to
23 * an application.
24 *
25 * Solaris implements an uncached I/O facility called directio() that
26 * is used for backups and sequential I/O to very large files. Solaris
27 * also supports uncaching whole NFS partitions with "-o forcedirectio,"
28 * an undocumented mount option.
29 *
30 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
31 * help from Andrew Morton.
32 *
33 * 18 Dec 2001 Initial implementation for 2.4 --cel
34 * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy
35 * 08 Jun 2003 Port to 2.5 APIs --cel
36 * 31 Mar 2004 Handle direct I/O without VFS support --cel
37 * 15 Sep 2004 Parallel async reads --cel
38 * 04 May 2005 support O_DIRECT with aio --cel
39 *
40 */
41
42 #include <linux/errno.h>
43 #include <linux/sched.h>
44 #include <linux/kernel.h>
45 #include <linux/file.h>
46 #include <linux/pagemap.h>
47 #include <linux/kref.h>
48 #include <linux/slab.h>
49 #include <linux/task_io_accounting_ops.h>
50 #include <linux/module.h>
51
52 #include <linux/nfs_fs.h>
53 #include <linux/nfs_page.h>
54 #include <linux/sunrpc/clnt.h>
55
56 #include <linux/uaccess.h>
57 #include <linux/atomic.h>
58
59 #include "internal.h"
60 #include "iostat.h"
61 #include "pnfs.h"
62
63 #define NFSDBG_FACILITY NFSDBG_VFS
64
65 static struct kmem_cache *nfs_direct_cachep;
66
67 struct nfs_direct_req {
68 struct kref kref; /* release manager */
69
70 /* I/O parameters */
71 struct nfs_open_context *ctx; /* file open context info */
72 struct nfs_lock_context *l_ctx; /* Lock context info */
73 struct kiocb * iocb; /* controlling i/o request */
74 struct inode * inode; /* target file of i/o */
75
76 /* completion state */
77 atomic_t io_count; /* i/os we're waiting for */
78 spinlock_t lock; /* protect completion state */
79
80 loff_t io_start; /* Start offset for I/O */
81 ssize_t count, /* bytes actually processed */
82 max_count, /* max expected count */
83 bytes_left, /* bytes left to be sent */
84 error; /* any reported error */
85 struct completion completion; /* wait for i/o completion */
86
87 /* commit state */
88 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
89 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
90 struct work_struct work;
91 int flags;
92 /* for write */
93 #define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
94 #define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
95 /* for read */
96 #define NFS_ODIRECT_SHOULD_DIRTY (3) /* dirty user-space page after read */
97 #define NFS_ODIRECT_DONE INT_MAX /* write verification failed */
98 };
99
100 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
101 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
102 static void nfs_direct_write_complete(struct nfs_direct_req *dreq);
103 static void nfs_direct_write_schedule_work(struct work_struct *work);
104
get_dreq(struct nfs_direct_req * dreq)105 static inline void get_dreq(struct nfs_direct_req *dreq)
106 {
107 atomic_inc(&dreq->io_count);
108 }
109
put_dreq(struct nfs_direct_req * dreq)110 static inline int put_dreq(struct nfs_direct_req *dreq)
111 {
112 return atomic_dec_and_test(&dreq->io_count);
113 }
114
115 static void
nfs_direct_handle_truncated(struct nfs_direct_req * dreq,const struct nfs_pgio_header * hdr,ssize_t dreq_len)116 nfs_direct_handle_truncated(struct nfs_direct_req *dreq,
117 const struct nfs_pgio_header *hdr,
118 ssize_t dreq_len)
119 {
120 if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||
121 test_bit(NFS_IOHDR_EOF, &hdr->flags)))
122 return;
123 if (dreq->max_count >= dreq_len) {
124 dreq->max_count = dreq_len;
125 if (dreq->count > dreq_len)
126 dreq->count = dreq_len;
127
128 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
129 dreq->error = hdr->error;
130 else /* Clear outstanding error if this is EOF */
131 dreq->error = 0;
132 }
133 }
134
135 static void
nfs_direct_count_bytes(struct nfs_direct_req * dreq,const struct nfs_pgio_header * hdr)136 nfs_direct_count_bytes(struct nfs_direct_req *dreq,
137 const struct nfs_pgio_header *hdr)
138 {
139 loff_t hdr_end = hdr->io_start + hdr->good_bytes;
140 ssize_t dreq_len = 0;
141
142 if (hdr_end > dreq->io_start)
143 dreq_len = hdr_end - dreq->io_start;
144
145 nfs_direct_handle_truncated(dreq, hdr, dreq_len);
146
147 if (dreq_len > dreq->max_count)
148 dreq_len = dreq->max_count;
149
150 if (dreq->count < dreq_len)
151 dreq->count = dreq_len;
152 }
153
154 /**
155 * nfs_direct_IO - NFS address space operation for direct I/O
156 * @iocb: target I/O control block
157 * @iter: I/O buffer
158 *
159 * The presence of this routine in the address space ops vector means
160 * the NFS client supports direct I/O. However, for most direct IO, we
161 * shunt off direct read and write requests before the VFS gets them,
162 * so this method is only ever called for swap.
163 */
nfs_direct_IO(struct kiocb * iocb,struct iov_iter * iter)164 ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
165 {
166 struct inode *inode = iocb->ki_filp->f_mapping->host;
167
168 /* we only support swap file calling nfs_direct_IO */
169 if (!IS_SWAPFILE(inode))
170 return 0;
171
172 VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE);
173
174 if (iov_iter_rw(iter) == READ)
175 return nfs_file_direct_read(iocb, iter);
176 return nfs_file_direct_write(iocb, iter);
177 }
178
nfs_direct_release_pages(struct page ** pages,unsigned int npages)179 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
180 {
181 unsigned int i;
182 for (i = 0; i < npages; i++)
183 put_page(pages[i]);
184 }
185
nfs_init_cinfo_from_dreq(struct nfs_commit_info * cinfo,struct nfs_direct_req * dreq)186 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
187 struct nfs_direct_req *dreq)
188 {
189 cinfo->inode = dreq->inode;
190 cinfo->mds = &dreq->mds_cinfo;
191 cinfo->ds = &dreq->ds_cinfo;
192 cinfo->dreq = dreq;
193 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
194 }
195
nfs_direct_req_alloc(void)196 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
197 {
198 struct nfs_direct_req *dreq;
199
200 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
201 if (!dreq)
202 return NULL;
203
204 kref_init(&dreq->kref);
205 kref_get(&dreq->kref);
206 init_completion(&dreq->completion);
207 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
208 pnfs_init_ds_commit_info(&dreq->ds_cinfo);
209 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
210 spin_lock_init(&dreq->lock);
211
212 return dreq;
213 }
214
nfs_direct_req_free(struct kref * kref)215 static void nfs_direct_req_free(struct kref *kref)
216 {
217 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
218
219 pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode);
220 if (dreq->l_ctx != NULL)
221 nfs_put_lock_context(dreq->l_ctx);
222 if (dreq->ctx != NULL)
223 put_nfs_open_context(dreq->ctx);
224 kmem_cache_free(nfs_direct_cachep, dreq);
225 }
226
nfs_direct_req_release(struct nfs_direct_req * dreq)227 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
228 {
229 kref_put(&dreq->kref, nfs_direct_req_free);
230 }
231
nfs_dreq_bytes_left(struct nfs_direct_req * dreq)232 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
233 {
234 return dreq->bytes_left;
235 }
236 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
237
238 /*
239 * Collects and returns the final error value/byte-count.
240 */
nfs_direct_wait(struct nfs_direct_req * dreq)241 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
242 {
243 ssize_t result = -EIOCBQUEUED;
244
245 /* Async requests don't wait here */
246 if (dreq->iocb)
247 goto out;
248
249 result = wait_for_completion_killable(&dreq->completion);
250
251 if (!result) {
252 result = dreq->count;
253 WARN_ON_ONCE(dreq->count < 0);
254 }
255 if (!result)
256 result = dreq->error;
257
258 out:
259 return (ssize_t) result;
260 }
261
262 /*
263 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
264 * the iocb is still valid here if this is a synchronous request.
265 */
nfs_direct_complete(struct nfs_direct_req * dreq)266 static void nfs_direct_complete(struct nfs_direct_req *dreq)
267 {
268 struct inode *inode = dreq->inode;
269
270 inode_dio_end(inode);
271
272 if (dreq->iocb) {
273 long res = (long) dreq->error;
274 if (dreq->count != 0) {
275 res = (long) dreq->count;
276 WARN_ON_ONCE(dreq->count < 0);
277 }
278 dreq->iocb->ki_complete(dreq->iocb, res, 0);
279 }
280
281 complete(&dreq->completion);
282
283 nfs_direct_req_release(dreq);
284 }
285
nfs_direct_read_completion(struct nfs_pgio_header * hdr)286 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
287 {
288 unsigned long bytes = 0;
289 struct nfs_direct_req *dreq = hdr->dreq;
290
291 spin_lock(&dreq->lock);
292 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
293 spin_unlock(&dreq->lock);
294 goto out_put;
295 }
296
297 nfs_direct_count_bytes(dreq, hdr);
298 spin_unlock(&dreq->lock);
299
300 while (!list_empty(&hdr->pages)) {
301 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
302 struct page *page = req->wb_page;
303
304 if (!PageCompound(page) && bytes < hdr->good_bytes &&
305 (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
306 set_page_dirty(page);
307 bytes += req->wb_bytes;
308 nfs_list_remove_request(req);
309 nfs_release_request(req);
310 }
311 out_put:
312 if (put_dreq(dreq))
313 nfs_direct_complete(dreq);
314 hdr->release(hdr);
315 }
316
nfs_read_sync_pgio_error(struct list_head * head,int error)317 static void nfs_read_sync_pgio_error(struct list_head *head, int error)
318 {
319 struct nfs_page *req;
320
321 while (!list_empty(head)) {
322 req = nfs_list_entry(head->next);
323 nfs_list_remove_request(req);
324 nfs_release_request(req);
325 }
326 }
327
nfs_direct_pgio_init(struct nfs_pgio_header * hdr)328 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
329 {
330 get_dreq(hdr->dreq);
331 }
332
333 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
334 .error_cleanup = nfs_read_sync_pgio_error,
335 .init_hdr = nfs_direct_pgio_init,
336 .completion = nfs_direct_read_completion,
337 };
338
339 /*
340 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
341 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
342 * bail and stop sending more reads. Read length accounting is
343 * handled automatically by nfs_direct_read_result(). Otherwise, if
344 * no requests have been sent, just return an error.
345 */
346
nfs_direct_read_schedule_iovec(struct nfs_direct_req * dreq,struct iov_iter * iter,loff_t pos)347 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
348 struct iov_iter *iter,
349 loff_t pos)
350 {
351 struct nfs_pageio_descriptor desc;
352 struct inode *inode = dreq->inode;
353 ssize_t result = -EINVAL;
354 size_t requested_bytes = 0;
355 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
356
357 nfs_pageio_init_read(&desc, dreq->inode, false,
358 &nfs_direct_read_completion_ops);
359 get_dreq(dreq);
360 desc.pg_dreq = dreq;
361 inode_dio_begin(inode);
362
363 while (iov_iter_count(iter)) {
364 struct page **pagevec;
365 size_t bytes;
366 size_t pgbase;
367 unsigned npages, i;
368
369 result = iov_iter_get_pages_alloc(iter, &pagevec,
370 rsize, &pgbase);
371 if (result < 0)
372 break;
373
374 bytes = result;
375 iov_iter_advance(iter, bytes);
376 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
377 for (i = 0; i < npages; i++) {
378 struct nfs_page *req;
379 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
380 /* XXX do we need to do the eof zeroing found in async_filler? */
381 req = nfs_create_request(dreq->ctx, pagevec[i],
382 pgbase, req_len);
383 if (IS_ERR(req)) {
384 result = PTR_ERR(req);
385 break;
386 }
387 req->wb_index = pos >> PAGE_SHIFT;
388 req->wb_offset = pos & ~PAGE_MASK;
389 if (!nfs_pageio_add_request(&desc, req)) {
390 result = desc.pg_error;
391 nfs_release_request(req);
392 break;
393 }
394 pgbase = 0;
395 bytes -= req_len;
396 requested_bytes += req_len;
397 pos += req_len;
398 dreq->bytes_left -= req_len;
399 }
400 nfs_direct_release_pages(pagevec, npages);
401 kvfree(pagevec);
402 if (result < 0)
403 break;
404 }
405
406 nfs_pageio_complete(&desc);
407
408 /*
409 * If no bytes were started, return the error, and let the
410 * generic layer handle the completion.
411 */
412 if (requested_bytes == 0) {
413 inode_dio_end(inode);
414 nfs_direct_req_release(dreq);
415 return result < 0 ? result : -EIO;
416 }
417
418 if (put_dreq(dreq))
419 nfs_direct_complete(dreq);
420 return requested_bytes;
421 }
422
423 /**
424 * nfs_file_direct_read - file direct read operation for NFS files
425 * @iocb: target I/O control block
426 * @iter: vector of user buffers into which to read data
427 *
428 * We use this function for direct reads instead of calling
429 * generic_file_aio_read() in order to avoid gfar's check to see if
430 * the request starts before the end of the file. For that check
431 * to work, we must generate a GETATTR before each direct read, and
432 * even then there is a window between the GETATTR and the subsequent
433 * READ where the file size could change. Our preference is simply
434 * to do all reads the application wants, and the server will take
435 * care of managing the end of file boundary.
436 *
437 * This function also eliminates unnecessarily updating the file's
438 * atime locally, as the NFS server sets the file's atime, and this
439 * client must read the updated atime from the server back into its
440 * cache.
441 */
nfs_file_direct_read(struct kiocb * iocb,struct iov_iter * iter)442 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
443 {
444 struct file *file = iocb->ki_filp;
445 struct address_space *mapping = file->f_mapping;
446 struct inode *inode = mapping->host;
447 struct nfs_direct_req *dreq;
448 struct nfs_lock_context *l_ctx;
449 ssize_t result, requested;
450 size_t count = iov_iter_count(iter);
451 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
452
453 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
454 file, count, (long long) iocb->ki_pos);
455
456 result = 0;
457 if (!count)
458 goto out;
459
460 task_io_account_read(count);
461
462 result = -ENOMEM;
463 dreq = nfs_direct_req_alloc();
464 if (dreq == NULL)
465 goto out;
466
467 dreq->inode = inode;
468 dreq->bytes_left = dreq->max_count = count;
469 dreq->io_start = iocb->ki_pos;
470 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
471 l_ctx = nfs_get_lock_context(dreq->ctx);
472 if (IS_ERR(l_ctx)) {
473 result = PTR_ERR(l_ctx);
474 nfs_direct_req_release(dreq);
475 goto out_release;
476 }
477 dreq->l_ctx = l_ctx;
478 if (!is_sync_kiocb(iocb))
479 dreq->iocb = iocb;
480
481 if (iter_is_iovec(iter))
482 dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
483
484 nfs_start_io_direct(inode);
485
486 NFS_I(inode)->read_io += count;
487 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
488
489 nfs_end_io_direct(inode);
490
491 if (requested > 0) {
492 result = nfs_direct_wait(dreq);
493 if (result > 0) {
494 requested -= result;
495 iocb->ki_pos += result;
496 }
497 iov_iter_revert(iter, requested);
498 } else {
499 result = requested;
500 }
501
502 out_release:
503 nfs_direct_req_release(dreq);
504 out:
505 return result;
506 }
507
508 static void
nfs_direct_join_group(struct list_head * list,struct inode * inode)509 nfs_direct_join_group(struct list_head *list, struct inode *inode)
510 {
511 struct nfs_page *req, *next;
512
513 list_for_each_entry(req, list, wb_list) {
514 if (req->wb_head != req || req->wb_this_page == req)
515 continue;
516 for (next = req->wb_this_page;
517 next != req->wb_head;
518 next = next->wb_this_page) {
519 nfs_list_remove_request(next);
520 nfs_release_request(next);
521 }
522 nfs_join_page_group(req, inode);
523 }
524 }
525
526 static void
nfs_direct_write_scan_commit_list(struct inode * inode,struct list_head * list,struct nfs_commit_info * cinfo)527 nfs_direct_write_scan_commit_list(struct inode *inode,
528 struct list_head *list,
529 struct nfs_commit_info *cinfo)
530 {
531 mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
532 pnfs_recover_commit_reqs(list, cinfo);
533 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
534 mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
535 }
536
nfs_direct_write_reschedule(struct nfs_direct_req * dreq)537 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
538 {
539 struct nfs_pageio_descriptor desc;
540 struct nfs_page *req, *tmp;
541 LIST_HEAD(reqs);
542 struct nfs_commit_info cinfo;
543 LIST_HEAD(failed);
544
545 nfs_init_cinfo_from_dreq(&cinfo, dreq);
546 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
547
548 nfs_direct_join_group(&reqs, dreq->inode);
549
550 dreq->count = 0;
551 dreq->max_count = 0;
552 list_for_each_entry(req, &reqs, wb_list)
553 dreq->max_count += req->wb_bytes;
554 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
555 get_dreq(dreq);
556
557 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
558 &nfs_direct_write_completion_ops);
559 desc.pg_dreq = dreq;
560
561 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
562 /* Bump the transmission count */
563 req->wb_nio++;
564 if (!nfs_pageio_add_request(&desc, req)) {
565 nfs_list_move_request(req, &failed);
566 spin_lock(&cinfo.inode->i_lock);
567 dreq->flags = 0;
568 if (desc.pg_error < 0)
569 dreq->error = desc.pg_error;
570 else
571 dreq->error = -EIO;
572 spin_unlock(&cinfo.inode->i_lock);
573 }
574 nfs_release_request(req);
575 }
576 nfs_pageio_complete(&desc);
577
578 while (!list_empty(&failed)) {
579 req = nfs_list_entry(failed.next);
580 nfs_list_remove_request(req);
581 nfs_unlock_and_release_request(req);
582 }
583
584 if (put_dreq(dreq))
585 nfs_direct_write_complete(dreq);
586 }
587
nfs_direct_commit_complete(struct nfs_commit_data * data)588 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
589 {
590 const struct nfs_writeverf *verf = data->res.verf;
591 struct nfs_direct_req *dreq = data->dreq;
592 struct nfs_commit_info cinfo;
593 struct nfs_page *req;
594 int status = data->task.tk_status;
595
596 if (status < 0) {
597 /* Errors in commit are fatal */
598 dreq->error = status;
599 dreq->max_count = 0;
600 dreq->count = 0;
601 dreq->flags = NFS_ODIRECT_DONE;
602 } else if (dreq->flags == NFS_ODIRECT_DONE)
603 status = dreq->error;
604
605 nfs_init_cinfo_from_dreq(&cinfo, dreq);
606
607 while (!list_empty(&data->pages)) {
608 req = nfs_list_entry(data->pages.next);
609 nfs_list_remove_request(req);
610 if (status >= 0 && !nfs_write_match_verf(verf, req)) {
611 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
612 /*
613 * Despite the reboot, the write was successful,
614 * so reset wb_nio.
615 */
616 req->wb_nio = 0;
617 nfs_mark_request_commit(req, NULL, &cinfo, 0);
618 } else /* Error or match */
619 nfs_release_request(req);
620 nfs_unlock_and_release_request(req);
621 }
622
623 if (nfs_commit_end(cinfo.mds))
624 nfs_direct_write_complete(dreq);
625 }
626
nfs_direct_resched_write(struct nfs_commit_info * cinfo,struct nfs_page * req)627 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
628 struct nfs_page *req)
629 {
630 struct nfs_direct_req *dreq = cinfo->dreq;
631
632 spin_lock(&dreq->lock);
633 if (dreq->flags != NFS_ODIRECT_DONE)
634 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
635 spin_unlock(&dreq->lock);
636 nfs_mark_request_commit(req, NULL, cinfo, 0);
637 }
638
639 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
640 .completion = nfs_direct_commit_complete,
641 .resched_write = nfs_direct_resched_write,
642 };
643
nfs_direct_commit_schedule(struct nfs_direct_req * dreq)644 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
645 {
646 int res;
647 struct nfs_commit_info cinfo;
648 LIST_HEAD(mds_list);
649
650 nfs_init_cinfo_from_dreq(&cinfo, dreq);
651 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
652 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
653 if (res < 0) /* res == -ENOMEM */
654 nfs_direct_write_reschedule(dreq);
655 }
656
nfs_direct_write_clear_reqs(struct nfs_direct_req * dreq)657 static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)
658 {
659 struct nfs_commit_info cinfo;
660 struct nfs_page *req;
661 LIST_HEAD(reqs);
662
663 nfs_init_cinfo_from_dreq(&cinfo, dreq);
664 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
665
666 while (!list_empty(&reqs)) {
667 req = nfs_list_entry(reqs.next);
668 nfs_list_remove_request(req);
669 nfs_release_request(req);
670 nfs_unlock_and_release_request(req);
671 }
672 }
673
nfs_direct_write_schedule_work(struct work_struct * work)674 static void nfs_direct_write_schedule_work(struct work_struct *work)
675 {
676 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
677 int flags = dreq->flags;
678
679 dreq->flags = 0;
680 switch (flags) {
681 case NFS_ODIRECT_DO_COMMIT:
682 nfs_direct_commit_schedule(dreq);
683 break;
684 case NFS_ODIRECT_RESCHED_WRITES:
685 nfs_direct_write_reschedule(dreq);
686 break;
687 default:
688 nfs_direct_write_clear_reqs(dreq);
689 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
690 nfs_direct_complete(dreq);
691 }
692 }
693
nfs_direct_write_complete(struct nfs_direct_req * dreq)694 static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
695 {
696 queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */
697 }
698
nfs_direct_write_completion(struct nfs_pgio_header * hdr)699 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
700 {
701 struct nfs_direct_req *dreq = hdr->dreq;
702 struct nfs_commit_info cinfo;
703 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
704 int flags = NFS_ODIRECT_DONE;
705
706 nfs_init_cinfo_from_dreq(&cinfo, dreq);
707
708 spin_lock(&dreq->lock);
709 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
710 spin_unlock(&dreq->lock);
711 goto out_put;
712 }
713
714 nfs_direct_count_bytes(dreq, hdr);
715 if (hdr->good_bytes != 0 && nfs_write_need_commit(hdr)) {
716 if (!dreq->flags)
717 dreq->flags = NFS_ODIRECT_DO_COMMIT;
718 flags = dreq->flags;
719 }
720 spin_unlock(&dreq->lock);
721
722 while (!list_empty(&hdr->pages)) {
723
724 req = nfs_list_entry(hdr->pages.next);
725 nfs_list_remove_request(req);
726 if (flags == NFS_ODIRECT_DO_COMMIT) {
727 kref_get(&req->wb_kref);
728 memcpy(&req->wb_verf, &hdr->verf.verifier,
729 sizeof(req->wb_verf));
730 nfs_mark_request_commit(req, hdr->lseg, &cinfo,
731 hdr->ds_commit_idx);
732 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
733 kref_get(&req->wb_kref);
734 nfs_mark_request_commit(req, NULL, &cinfo, 0);
735 }
736 nfs_unlock_and_release_request(req);
737 }
738
739 out_put:
740 if (put_dreq(dreq))
741 nfs_direct_write_complete(dreq);
742 hdr->release(hdr);
743 }
744
nfs_write_sync_pgio_error(struct list_head * head,int error)745 static void nfs_write_sync_pgio_error(struct list_head *head, int error)
746 {
747 struct nfs_page *req;
748
749 while (!list_empty(head)) {
750 req = nfs_list_entry(head->next);
751 nfs_list_remove_request(req);
752 nfs_unlock_and_release_request(req);
753 }
754 }
755
nfs_direct_write_reschedule_io(struct nfs_pgio_header * hdr)756 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
757 {
758 struct nfs_direct_req *dreq = hdr->dreq;
759
760 spin_lock(&dreq->lock);
761 if (dreq->error == 0) {
762 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
763 /* fake unstable write to let common nfs resend pages */
764 hdr->verf.committed = NFS_UNSTABLE;
765 hdr->good_bytes = hdr->args.offset + hdr->args.count -
766 hdr->io_start;
767 }
768 spin_unlock(&dreq->lock);
769 }
770
771 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
772 .error_cleanup = nfs_write_sync_pgio_error,
773 .init_hdr = nfs_direct_pgio_init,
774 .completion = nfs_direct_write_completion,
775 .reschedule_io = nfs_direct_write_reschedule_io,
776 };
777
778
779 /*
780 * NB: Return the value of the first error return code. Subsequent
781 * errors after the first one are ignored.
782 */
783 /*
784 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
785 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
786 * bail and stop sending more writes. Write length accounting is
787 * handled automatically by nfs_direct_write_result(). Otherwise, if
788 * no requests have been sent, just return an error.
789 */
nfs_direct_write_schedule_iovec(struct nfs_direct_req * dreq,struct iov_iter * iter,loff_t pos)790 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
791 struct iov_iter *iter,
792 loff_t pos)
793 {
794 struct nfs_pageio_descriptor desc;
795 struct inode *inode = dreq->inode;
796 ssize_t result = 0;
797 size_t requested_bytes = 0;
798 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
799
800 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false,
801 &nfs_direct_write_completion_ops);
802 desc.pg_dreq = dreq;
803 get_dreq(dreq);
804 inode_dio_begin(inode);
805
806 NFS_I(inode)->write_io += iov_iter_count(iter);
807 while (iov_iter_count(iter)) {
808 struct page **pagevec;
809 size_t bytes;
810 size_t pgbase;
811 unsigned npages, i;
812
813 result = iov_iter_get_pages_alloc(iter, &pagevec,
814 wsize, &pgbase);
815 if (result < 0)
816 break;
817
818 bytes = result;
819 iov_iter_advance(iter, bytes);
820 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
821 for (i = 0; i < npages; i++) {
822 struct nfs_page *req;
823 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
824
825 req = nfs_create_request(dreq->ctx, pagevec[i],
826 pgbase, req_len);
827 if (IS_ERR(req)) {
828 result = PTR_ERR(req);
829 break;
830 }
831
832 if (desc.pg_error < 0) {
833 nfs_free_request(req);
834 result = desc.pg_error;
835 break;
836 }
837
838 nfs_lock_request(req);
839 req->wb_index = pos >> PAGE_SHIFT;
840 req->wb_offset = pos & ~PAGE_MASK;
841 if (!nfs_pageio_add_request(&desc, req)) {
842 result = desc.pg_error;
843 nfs_unlock_and_release_request(req);
844 break;
845 }
846 pgbase = 0;
847 bytes -= req_len;
848 requested_bytes += req_len;
849 pos += req_len;
850 dreq->bytes_left -= req_len;
851 }
852 nfs_direct_release_pages(pagevec, npages);
853 kvfree(pagevec);
854 if (result < 0)
855 break;
856 }
857 nfs_pageio_complete(&desc);
858
859 /*
860 * If no bytes were started, return the error, and let the
861 * generic layer handle the completion.
862 */
863 if (requested_bytes == 0) {
864 inode_dio_end(inode);
865 nfs_direct_req_release(dreq);
866 return result < 0 ? result : -EIO;
867 }
868
869 if (put_dreq(dreq))
870 nfs_direct_write_complete(dreq);
871 return requested_bytes;
872 }
873
874 /**
875 * nfs_file_direct_write - file direct write operation for NFS files
876 * @iocb: target I/O control block
877 * @iter: vector of user buffers from which to write data
878 *
879 * We use this function for direct writes instead of calling
880 * generic_file_aio_write() in order to avoid taking the inode
881 * semaphore and updating the i_size. The NFS server will set
882 * the new i_size and this client must read the updated size
883 * back into its cache. We let the server do generic write
884 * parameter checking and report problems.
885 *
886 * We eliminate local atime updates, see direct read above.
887 *
888 * We avoid unnecessary page cache invalidations for normal cached
889 * readers of this file.
890 *
891 * Note that O_APPEND is not supported for NFS direct writes, as there
892 * is no atomic O_APPEND write facility in the NFS protocol.
893 */
nfs_file_direct_write(struct kiocb * iocb,struct iov_iter * iter)894 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
895 {
896 ssize_t result, requested;
897 size_t count;
898 struct file *file = iocb->ki_filp;
899 struct address_space *mapping = file->f_mapping;
900 struct inode *inode = mapping->host;
901 struct nfs_direct_req *dreq;
902 struct nfs_lock_context *l_ctx;
903 loff_t pos, end;
904
905 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
906 file, iov_iter_count(iter), (long long) iocb->ki_pos);
907
908 result = generic_write_checks(iocb, iter);
909 if (result <= 0)
910 return result;
911 count = result;
912 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
913
914 pos = iocb->ki_pos;
915 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
916
917 task_io_account_write(count);
918
919 result = -ENOMEM;
920 dreq = nfs_direct_req_alloc();
921 if (!dreq)
922 goto out;
923
924 dreq->inode = inode;
925 dreq->bytes_left = dreq->max_count = count;
926 dreq->io_start = pos;
927 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
928 l_ctx = nfs_get_lock_context(dreq->ctx);
929 if (IS_ERR(l_ctx)) {
930 result = PTR_ERR(l_ctx);
931 nfs_direct_req_release(dreq);
932 goto out_release;
933 }
934 dreq->l_ctx = l_ctx;
935 if (!is_sync_kiocb(iocb))
936 dreq->iocb = iocb;
937 pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode);
938
939 nfs_start_io_direct(inode);
940
941 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos);
942
943 if (mapping->nrpages) {
944 invalidate_inode_pages2_range(mapping,
945 pos >> PAGE_SHIFT, end);
946 }
947
948 nfs_end_io_direct(inode);
949
950 if (requested > 0) {
951 result = nfs_direct_wait(dreq);
952 if (result > 0) {
953 requested -= result;
954 iocb->ki_pos = pos + result;
955 /* XXX: should check the generic_write_sync retval */
956 generic_write_sync(iocb, result);
957 }
958 iov_iter_revert(iter, requested);
959 } else {
960 result = requested;
961 }
962 out_release:
963 nfs_direct_req_release(dreq);
964 out:
965 return result;
966 }
967
968 /**
969 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
970 *
971 */
nfs_init_directcache(void)972 int __init nfs_init_directcache(void)
973 {
974 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
975 sizeof(struct nfs_direct_req),
976 0, (SLAB_RECLAIM_ACCOUNT|
977 SLAB_MEM_SPREAD),
978 NULL);
979 if (nfs_direct_cachep == NULL)
980 return -ENOMEM;
981
982 return 0;
983 }
984
985 /**
986 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
987 *
988 */
nfs_destroy_directcache(void)989 void nfs_destroy_directcache(void)
990 {
991 kmem_cache_destroy(nfs_direct_cachep);
992 }
993