xref: /openbmc/linux/fs/nfs/direct.c (revision fd589a8f)
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 
48 #include <linux/nfs_fs.h>
49 #include <linux/nfs_page.h>
50 #include <linux/sunrpc/clnt.h>
51 
52 #include <asm/system.h>
53 #include <asm/uaccess.h>
54 #include <asm/atomic.h>
55 
56 #include "internal.h"
57 #include "iostat.h"
58 
59 #define NFSDBG_FACILITY		NFSDBG_VFS
60 
61 static struct kmem_cache *nfs_direct_cachep;
62 
63 /*
64  * This represents a set of asynchronous requests that we're waiting on
65  */
66 struct nfs_direct_req {
67 	struct kref		kref;		/* release manager */
68 
69 	/* I/O parameters */
70 	struct nfs_open_context	*ctx;		/* file open context info */
71 	struct kiocb *		iocb;		/* controlling i/o request */
72 	struct inode *		inode;		/* target file of i/o */
73 
74 	/* completion state */
75 	atomic_t		io_count;	/* i/os we're waiting for */
76 	spinlock_t		lock;		/* protect completion state */
77 	ssize_t			count,		/* bytes actually processed */
78 				error;		/* any reported error */
79 	struct completion	completion;	/* wait for i/o completion */
80 
81 	/* commit state */
82 	struct list_head	rewrite_list;	/* saved nfs_write_data structs */
83 	struct nfs_write_data *	commit_data;	/* special write_data for commits */
84 	int			flags;
85 #define NFS_ODIRECT_DO_COMMIT		(1)	/* an unstable reply was received */
86 #define NFS_ODIRECT_RESCHED_WRITES	(2)	/* write verification failed */
87 	struct nfs_writeverf	verf;		/* unstable write verifier */
88 };
89 
90 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
91 static const struct rpc_call_ops nfs_write_direct_ops;
92 
93 static inline void get_dreq(struct nfs_direct_req *dreq)
94 {
95 	atomic_inc(&dreq->io_count);
96 }
97 
98 static inline int put_dreq(struct nfs_direct_req *dreq)
99 {
100 	return atomic_dec_and_test(&dreq->io_count);
101 }
102 
103 /**
104  * nfs_direct_IO - NFS address space operation for direct I/O
105  * @rw: direction (read or write)
106  * @iocb: target I/O control block
107  * @iov: array of vectors that define I/O buffer
108  * @pos: offset in file to begin the operation
109  * @nr_segs: size of iovec array
110  *
111  * The presence of this routine in the address space ops vector means
112  * the NFS client supports direct I/O.  However, we shunt off direct
113  * read and write requests before the VFS gets them, so this method
114  * should never be called.
115  */
116 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
117 {
118 	dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
119 			iocb->ki_filp->f_path.dentry->d_name.name,
120 			(long long) pos, nr_segs);
121 
122 	return -EINVAL;
123 }
124 
125 static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
126 {
127 	unsigned int npages;
128 	unsigned int i;
129 
130 	if (count == 0)
131 		return;
132 	pages += (pgbase >> PAGE_SHIFT);
133 	npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
134 	for (i = 0; i < npages; i++) {
135 		struct page *page = pages[i];
136 		if (!PageCompound(page))
137 			set_page_dirty(page);
138 	}
139 }
140 
141 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
142 {
143 	unsigned int i;
144 	for (i = 0; i < npages; i++)
145 		page_cache_release(pages[i]);
146 }
147 
148 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
149 {
150 	struct nfs_direct_req *dreq;
151 
152 	dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
153 	if (!dreq)
154 		return NULL;
155 
156 	kref_init(&dreq->kref);
157 	kref_get(&dreq->kref);
158 	init_completion(&dreq->completion);
159 	INIT_LIST_HEAD(&dreq->rewrite_list);
160 	dreq->iocb = NULL;
161 	dreq->ctx = NULL;
162 	spin_lock_init(&dreq->lock);
163 	atomic_set(&dreq->io_count, 0);
164 	dreq->count = 0;
165 	dreq->error = 0;
166 	dreq->flags = 0;
167 
168 	return dreq;
169 }
170 
171 static void nfs_direct_req_free(struct kref *kref)
172 {
173 	struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
174 
175 	if (dreq->ctx != NULL)
176 		put_nfs_open_context(dreq->ctx);
177 	kmem_cache_free(nfs_direct_cachep, dreq);
178 }
179 
180 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
181 {
182 	kref_put(&dreq->kref, nfs_direct_req_free);
183 }
184 
185 /*
186  * Collects and returns the final error value/byte-count.
187  */
188 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
189 {
190 	ssize_t result = -EIOCBQUEUED;
191 
192 	/* Async requests don't wait here */
193 	if (dreq->iocb)
194 		goto out;
195 
196 	result = wait_for_completion_killable(&dreq->completion);
197 
198 	if (!result)
199 		result = dreq->error;
200 	if (!result)
201 		result = dreq->count;
202 
203 out:
204 	return (ssize_t) result;
205 }
206 
207 /*
208  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
209  * the iocb is still valid here if this is a synchronous request.
210  */
211 static void nfs_direct_complete(struct nfs_direct_req *dreq)
212 {
213 	if (dreq->iocb) {
214 		long res = (long) dreq->error;
215 		if (!res)
216 			res = (long) dreq->count;
217 		aio_complete(dreq->iocb, res, 0);
218 	}
219 	complete_all(&dreq->completion);
220 
221 	nfs_direct_req_release(dreq);
222 }
223 
224 /*
225  * We must hold a reference to all the pages in this direct read request
226  * until the RPCs complete.  This could be long *after* we are woken up in
227  * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
228  */
229 static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
230 {
231 	struct nfs_read_data *data = calldata;
232 
233 	nfs_readpage_result(task, data);
234 }
235 
236 static void nfs_direct_read_release(void *calldata)
237 {
238 
239 	struct nfs_read_data *data = calldata;
240 	struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
241 	int status = data->task.tk_status;
242 
243 	spin_lock(&dreq->lock);
244 	if (unlikely(status < 0)) {
245 		dreq->error = status;
246 		spin_unlock(&dreq->lock);
247 	} else {
248 		dreq->count += data->res.count;
249 		spin_unlock(&dreq->lock);
250 		nfs_direct_dirty_pages(data->pagevec,
251 				data->args.pgbase,
252 				data->res.count);
253 	}
254 	nfs_direct_release_pages(data->pagevec, data->npages);
255 
256 	if (put_dreq(dreq))
257 		nfs_direct_complete(dreq);
258 	nfs_readdata_free(data);
259 }
260 
261 static const struct rpc_call_ops nfs_read_direct_ops = {
262 #if defined(CONFIG_NFS_V4_1)
263 	.rpc_call_prepare = nfs_read_prepare,
264 #endif /* CONFIG_NFS_V4_1 */
265 	.rpc_call_done = nfs_direct_read_result,
266 	.rpc_release = nfs_direct_read_release,
267 };
268 
269 /*
270  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
271  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
272  * bail and stop sending more reads.  Read length accounting is
273  * handled automatically by nfs_direct_read_result().  Otherwise, if
274  * no requests have been sent, just return an error.
275  */
276 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
277 						const struct iovec *iov,
278 						loff_t pos)
279 {
280 	struct nfs_open_context *ctx = dreq->ctx;
281 	struct inode *inode = ctx->path.dentry->d_inode;
282 	unsigned long user_addr = (unsigned long)iov->iov_base;
283 	size_t count = iov->iov_len;
284 	size_t rsize = NFS_SERVER(inode)->rsize;
285 	struct rpc_task *task;
286 	struct rpc_message msg = {
287 		.rpc_cred = ctx->cred,
288 	};
289 	struct rpc_task_setup task_setup_data = {
290 		.rpc_client = NFS_CLIENT(inode),
291 		.rpc_message = &msg,
292 		.callback_ops = &nfs_read_direct_ops,
293 		.workqueue = nfsiod_workqueue,
294 		.flags = RPC_TASK_ASYNC,
295 	};
296 	unsigned int pgbase;
297 	int result;
298 	ssize_t started = 0;
299 
300 	do {
301 		struct nfs_read_data *data;
302 		size_t bytes;
303 
304 		pgbase = user_addr & ~PAGE_MASK;
305 		bytes = min(rsize,count);
306 
307 		result = -ENOMEM;
308 		data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
309 		if (unlikely(!data))
310 			break;
311 
312 		down_read(&current->mm->mmap_sem);
313 		result = get_user_pages(current, current->mm, user_addr,
314 					data->npages, 1, 0, data->pagevec, NULL);
315 		up_read(&current->mm->mmap_sem);
316 		if (result < 0) {
317 			nfs_readdata_free(data);
318 			break;
319 		}
320 		if ((unsigned)result < data->npages) {
321 			bytes = result * PAGE_SIZE;
322 			if (bytes <= pgbase) {
323 				nfs_direct_release_pages(data->pagevec, result);
324 				nfs_readdata_free(data);
325 				break;
326 			}
327 			bytes -= pgbase;
328 			data->npages = result;
329 		}
330 
331 		get_dreq(dreq);
332 
333 		data->req = (struct nfs_page *) dreq;
334 		data->inode = inode;
335 		data->cred = msg.rpc_cred;
336 		data->args.fh = NFS_FH(inode);
337 		data->args.context = ctx;
338 		data->args.offset = pos;
339 		data->args.pgbase = pgbase;
340 		data->args.pages = data->pagevec;
341 		data->args.count = bytes;
342 		data->res.fattr = &data->fattr;
343 		data->res.eof = 0;
344 		data->res.count = bytes;
345 		msg.rpc_argp = &data->args;
346 		msg.rpc_resp = &data->res;
347 
348 		task_setup_data.task = &data->task;
349 		task_setup_data.callback_data = data;
350 		NFS_PROTO(inode)->read_setup(data, &msg);
351 
352 		task = rpc_run_task(&task_setup_data);
353 		if (IS_ERR(task))
354 			break;
355 		rpc_put_task(task);
356 
357 		dprintk("NFS: %5u initiated direct read call "
358 			"(req %s/%Ld, %zu bytes @ offset %Lu)\n",
359 				data->task.tk_pid,
360 				inode->i_sb->s_id,
361 				(long long)NFS_FILEID(inode),
362 				bytes,
363 				(unsigned long long)data->args.offset);
364 
365 		started += bytes;
366 		user_addr += bytes;
367 		pos += bytes;
368 		/* FIXME: Remove this unnecessary math from final patch */
369 		pgbase += bytes;
370 		pgbase &= ~PAGE_MASK;
371 		BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
372 
373 		count -= bytes;
374 	} while (count != 0);
375 
376 	if (started)
377 		return started;
378 	return result < 0 ? (ssize_t) result : -EFAULT;
379 }
380 
381 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
382 					      const struct iovec *iov,
383 					      unsigned long nr_segs,
384 					      loff_t pos)
385 {
386 	ssize_t result = -EINVAL;
387 	size_t requested_bytes = 0;
388 	unsigned long seg;
389 
390 	get_dreq(dreq);
391 
392 	for (seg = 0; seg < nr_segs; seg++) {
393 		const struct iovec *vec = &iov[seg];
394 		result = nfs_direct_read_schedule_segment(dreq, vec, pos);
395 		if (result < 0)
396 			break;
397 		requested_bytes += result;
398 		if ((size_t)result < vec->iov_len)
399 			break;
400 		pos += vec->iov_len;
401 	}
402 
403 	if (put_dreq(dreq))
404 		nfs_direct_complete(dreq);
405 
406 	if (requested_bytes != 0)
407 		return 0;
408 
409 	if (result < 0)
410 		return result;
411 	return -EIO;
412 }
413 
414 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
415 			       unsigned long nr_segs, loff_t pos)
416 {
417 	ssize_t result = 0;
418 	struct inode *inode = iocb->ki_filp->f_mapping->host;
419 	struct nfs_direct_req *dreq;
420 
421 	dreq = nfs_direct_req_alloc();
422 	if (!dreq)
423 		return -ENOMEM;
424 
425 	dreq->inode = inode;
426 	dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
427 	if (!is_sync_kiocb(iocb))
428 		dreq->iocb = iocb;
429 
430 	result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
431 	if (!result)
432 		result = nfs_direct_wait(dreq);
433 	nfs_direct_req_release(dreq);
434 
435 	return result;
436 }
437 
438 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
439 {
440 	while (!list_empty(&dreq->rewrite_list)) {
441 		struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
442 		list_del(&data->pages);
443 		nfs_direct_release_pages(data->pagevec, data->npages);
444 		nfs_writedata_free(data);
445 	}
446 }
447 
448 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
449 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
450 {
451 	struct inode *inode = dreq->inode;
452 	struct list_head *p;
453 	struct nfs_write_data *data;
454 	struct rpc_task *task;
455 	struct rpc_message msg = {
456 		.rpc_cred = dreq->ctx->cred,
457 	};
458 	struct rpc_task_setup task_setup_data = {
459 		.rpc_client = NFS_CLIENT(inode),
460 		.callback_ops = &nfs_write_direct_ops,
461 		.workqueue = nfsiod_workqueue,
462 		.flags = RPC_TASK_ASYNC,
463 	};
464 
465 	dreq->count = 0;
466 	get_dreq(dreq);
467 
468 	list_for_each(p, &dreq->rewrite_list) {
469 		data = list_entry(p, struct nfs_write_data, pages);
470 
471 		get_dreq(dreq);
472 
473 		/* Use stable writes */
474 		data->args.stable = NFS_FILE_SYNC;
475 
476 		/*
477 		 * Reset data->res.
478 		 */
479 		nfs_fattr_init(&data->fattr);
480 		data->res.count = data->args.count;
481 		memset(&data->verf, 0, sizeof(data->verf));
482 
483 		/*
484 		 * Reuse data->task; data->args should not have changed
485 		 * since the original request was sent.
486 		 */
487 		task_setup_data.task = &data->task;
488 		task_setup_data.callback_data = data;
489 		msg.rpc_argp = &data->args;
490 		msg.rpc_resp = &data->res;
491 		NFS_PROTO(inode)->write_setup(data, &msg);
492 
493 		/*
494 		 * We're called via an RPC callback, so BKL is already held.
495 		 */
496 		task = rpc_run_task(&task_setup_data);
497 		if (!IS_ERR(task))
498 			rpc_put_task(task);
499 
500 		dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
501 				data->task.tk_pid,
502 				inode->i_sb->s_id,
503 				(long long)NFS_FILEID(inode),
504 				data->args.count,
505 				(unsigned long long)data->args.offset);
506 	}
507 
508 	if (put_dreq(dreq))
509 		nfs_direct_write_complete(dreq, inode);
510 }
511 
512 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
513 {
514 	struct nfs_write_data *data = calldata;
515 
516 	/* Call the NFS version-specific code */
517 	NFS_PROTO(data->inode)->commit_done(task, data);
518 }
519 
520 static void nfs_direct_commit_release(void *calldata)
521 {
522 	struct nfs_write_data *data = calldata;
523 	struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
524 	int status = data->task.tk_status;
525 
526 	if (status < 0) {
527 		dprintk("NFS: %5u commit failed with error %d.\n",
528 				data->task.tk_pid, status);
529 		dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
530 	} else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
531 		dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
532 		dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
533 	}
534 
535 	dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
536 	nfs_direct_write_complete(dreq, data->inode);
537 	nfs_commit_free(data);
538 }
539 
540 static const struct rpc_call_ops nfs_commit_direct_ops = {
541 #if defined(CONFIG_NFS_V4_1)
542 	.rpc_call_prepare = nfs_write_prepare,
543 #endif /* CONFIG_NFS_V4_1 */
544 	.rpc_call_done = nfs_direct_commit_result,
545 	.rpc_release = nfs_direct_commit_release,
546 };
547 
548 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
549 {
550 	struct nfs_write_data *data = dreq->commit_data;
551 	struct rpc_task *task;
552 	struct rpc_message msg = {
553 		.rpc_argp = &data->args,
554 		.rpc_resp = &data->res,
555 		.rpc_cred = dreq->ctx->cred,
556 	};
557 	struct rpc_task_setup task_setup_data = {
558 		.task = &data->task,
559 		.rpc_client = NFS_CLIENT(dreq->inode),
560 		.rpc_message = &msg,
561 		.callback_ops = &nfs_commit_direct_ops,
562 		.callback_data = data,
563 		.workqueue = nfsiod_workqueue,
564 		.flags = RPC_TASK_ASYNC,
565 	};
566 
567 	data->inode = dreq->inode;
568 	data->cred = msg.rpc_cred;
569 
570 	data->args.fh = NFS_FH(data->inode);
571 	data->args.offset = 0;
572 	data->args.count = 0;
573 	data->args.context = dreq->ctx;
574 	data->res.count = 0;
575 	data->res.fattr = &data->fattr;
576 	data->res.verf = &data->verf;
577 
578 	NFS_PROTO(data->inode)->commit_setup(data, &msg);
579 
580 	/* Note: task.tk_ops->rpc_release will free dreq->commit_data */
581 	dreq->commit_data = NULL;
582 
583 	dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
584 
585 	task = rpc_run_task(&task_setup_data);
586 	if (!IS_ERR(task))
587 		rpc_put_task(task);
588 }
589 
590 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
591 {
592 	int flags = dreq->flags;
593 
594 	dreq->flags = 0;
595 	switch (flags) {
596 		case NFS_ODIRECT_DO_COMMIT:
597 			nfs_direct_commit_schedule(dreq);
598 			break;
599 		case NFS_ODIRECT_RESCHED_WRITES:
600 			nfs_direct_write_reschedule(dreq);
601 			break;
602 		default:
603 			if (dreq->commit_data != NULL)
604 				nfs_commit_free(dreq->commit_data);
605 			nfs_direct_free_writedata(dreq);
606 			nfs_zap_mapping(inode, inode->i_mapping);
607 			nfs_direct_complete(dreq);
608 	}
609 }
610 
611 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
612 {
613 	dreq->commit_data = nfs_commitdata_alloc();
614 	if (dreq->commit_data != NULL)
615 		dreq->commit_data->req = (struct nfs_page *) dreq;
616 }
617 #else
618 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
619 {
620 	dreq->commit_data = NULL;
621 }
622 
623 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
624 {
625 	nfs_direct_free_writedata(dreq);
626 	nfs_zap_mapping(inode, inode->i_mapping);
627 	nfs_direct_complete(dreq);
628 }
629 #endif
630 
631 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
632 {
633 	struct nfs_write_data *data = calldata;
634 
635 	if (nfs_writeback_done(task, data) != 0)
636 		return;
637 }
638 
639 /*
640  * NB: Return the value of the first error return code.  Subsequent
641  *     errors after the first one are ignored.
642  */
643 static void nfs_direct_write_release(void *calldata)
644 {
645 	struct nfs_write_data *data = calldata;
646 	struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
647 	int status = data->task.tk_status;
648 
649 	spin_lock(&dreq->lock);
650 
651 	if (unlikely(status < 0)) {
652 		/* An error has occurred, so we should not commit */
653 		dreq->flags = 0;
654 		dreq->error = status;
655 	}
656 	if (unlikely(dreq->error != 0))
657 		goto out_unlock;
658 
659 	dreq->count += data->res.count;
660 
661 	if (data->res.verf->committed != NFS_FILE_SYNC) {
662 		switch (dreq->flags) {
663 			case 0:
664 				memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
665 				dreq->flags = NFS_ODIRECT_DO_COMMIT;
666 				break;
667 			case NFS_ODIRECT_DO_COMMIT:
668 				if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
669 					dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
670 					dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
671 				}
672 		}
673 	}
674 out_unlock:
675 	spin_unlock(&dreq->lock);
676 
677 	if (put_dreq(dreq))
678 		nfs_direct_write_complete(dreq, data->inode);
679 }
680 
681 static const struct rpc_call_ops nfs_write_direct_ops = {
682 #if defined(CONFIG_NFS_V4_1)
683 	.rpc_call_prepare = nfs_write_prepare,
684 #endif /* CONFIG_NFS_V4_1 */
685 	.rpc_call_done = nfs_direct_write_result,
686 	.rpc_release = nfs_direct_write_release,
687 };
688 
689 /*
690  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
691  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
692  * bail and stop sending more writes.  Write length accounting is
693  * handled automatically by nfs_direct_write_result().  Otherwise, if
694  * no requests have been sent, just return an error.
695  */
696 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
697 						 const struct iovec *iov,
698 						 loff_t pos, int sync)
699 {
700 	struct nfs_open_context *ctx = dreq->ctx;
701 	struct inode *inode = ctx->path.dentry->d_inode;
702 	unsigned long user_addr = (unsigned long)iov->iov_base;
703 	size_t count = iov->iov_len;
704 	struct rpc_task *task;
705 	struct rpc_message msg = {
706 		.rpc_cred = ctx->cred,
707 	};
708 	struct rpc_task_setup task_setup_data = {
709 		.rpc_client = NFS_CLIENT(inode),
710 		.rpc_message = &msg,
711 		.callback_ops = &nfs_write_direct_ops,
712 		.workqueue = nfsiod_workqueue,
713 		.flags = RPC_TASK_ASYNC,
714 	};
715 	size_t wsize = NFS_SERVER(inode)->wsize;
716 	unsigned int pgbase;
717 	int result;
718 	ssize_t started = 0;
719 
720 	do {
721 		struct nfs_write_data *data;
722 		size_t bytes;
723 
724 		pgbase = user_addr & ~PAGE_MASK;
725 		bytes = min(wsize,count);
726 
727 		result = -ENOMEM;
728 		data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
729 		if (unlikely(!data))
730 			break;
731 
732 		down_read(&current->mm->mmap_sem);
733 		result = get_user_pages(current, current->mm, user_addr,
734 					data->npages, 0, 0, data->pagevec, NULL);
735 		up_read(&current->mm->mmap_sem);
736 		if (result < 0) {
737 			nfs_writedata_free(data);
738 			break;
739 		}
740 		if ((unsigned)result < data->npages) {
741 			bytes = result * PAGE_SIZE;
742 			if (bytes <= pgbase) {
743 				nfs_direct_release_pages(data->pagevec, result);
744 				nfs_writedata_free(data);
745 				break;
746 			}
747 			bytes -= pgbase;
748 			data->npages = result;
749 		}
750 
751 		get_dreq(dreq);
752 
753 		list_move_tail(&data->pages, &dreq->rewrite_list);
754 
755 		data->req = (struct nfs_page *) dreq;
756 		data->inode = inode;
757 		data->cred = msg.rpc_cred;
758 		data->args.fh = NFS_FH(inode);
759 		data->args.context = ctx;
760 		data->args.offset = pos;
761 		data->args.pgbase = pgbase;
762 		data->args.pages = data->pagevec;
763 		data->args.count = bytes;
764 		data->args.stable = sync;
765 		data->res.fattr = &data->fattr;
766 		data->res.count = bytes;
767 		data->res.verf = &data->verf;
768 
769 		task_setup_data.task = &data->task;
770 		task_setup_data.callback_data = data;
771 		msg.rpc_argp = &data->args;
772 		msg.rpc_resp = &data->res;
773 		NFS_PROTO(inode)->write_setup(data, &msg);
774 
775 		task = rpc_run_task(&task_setup_data);
776 		if (IS_ERR(task))
777 			break;
778 		rpc_put_task(task);
779 
780 		dprintk("NFS: %5u initiated direct write call "
781 			"(req %s/%Ld, %zu bytes @ offset %Lu)\n",
782 				data->task.tk_pid,
783 				inode->i_sb->s_id,
784 				(long long)NFS_FILEID(inode),
785 				bytes,
786 				(unsigned long long)data->args.offset);
787 
788 		started += bytes;
789 		user_addr += bytes;
790 		pos += bytes;
791 
792 		/* FIXME: Remove this useless math from the final patch */
793 		pgbase += bytes;
794 		pgbase &= ~PAGE_MASK;
795 		BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
796 
797 		count -= bytes;
798 	} while (count != 0);
799 
800 	if (started)
801 		return started;
802 	return result < 0 ? (ssize_t) result : -EFAULT;
803 }
804 
805 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
806 					       const struct iovec *iov,
807 					       unsigned long nr_segs,
808 					       loff_t pos, int sync)
809 {
810 	ssize_t result = 0;
811 	size_t requested_bytes = 0;
812 	unsigned long seg;
813 
814 	get_dreq(dreq);
815 
816 	for (seg = 0; seg < nr_segs; seg++) {
817 		const struct iovec *vec = &iov[seg];
818 		result = nfs_direct_write_schedule_segment(dreq, vec,
819 							   pos, sync);
820 		if (result < 0)
821 			break;
822 		requested_bytes += result;
823 		if ((size_t)result < vec->iov_len)
824 			break;
825 		pos += vec->iov_len;
826 	}
827 
828 	if (put_dreq(dreq))
829 		nfs_direct_write_complete(dreq, dreq->inode);
830 
831 	if (requested_bytes != 0)
832 		return 0;
833 
834 	if (result < 0)
835 		return result;
836 	return -EIO;
837 }
838 
839 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
840 				unsigned long nr_segs, loff_t pos,
841 				size_t count)
842 {
843 	ssize_t result = 0;
844 	struct inode *inode = iocb->ki_filp->f_mapping->host;
845 	struct nfs_direct_req *dreq;
846 	size_t wsize = NFS_SERVER(inode)->wsize;
847 	int sync = NFS_UNSTABLE;
848 
849 	dreq = nfs_direct_req_alloc();
850 	if (!dreq)
851 		return -ENOMEM;
852 	nfs_alloc_commit_data(dreq);
853 
854 	if (dreq->commit_data == NULL || count < wsize)
855 		sync = NFS_FILE_SYNC;
856 
857 	dreq->inode = inode;
858 	dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
859 	if (!is_sync_kiocb(iocb))
860 		dreq->iocb = iocb;
861 
862 	result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
863 	if (!result)
864 		result = nfs_direct_wait(dreq);
865 	nfs_direct_req_release(dreq);
866 
867 	return result;
868 }
869 
870 /**
871  * nfs_file_direct_read - file direct read operation for NFS files
872  * @iocb: target I/O control block
873  * @iov: vector of user buffers into which to read data
874  * @nr_segs: size of iov vector
875  * @pos: byte offset in file where reading starts
876  *
877  * We use this function for direct reads instead of calling
878  * generic_file_aio_read() in order to avoid gfar's check to see if
879  * the request starts before the end of the file.  For that check
880  * to work, we must generate a GETATTR before each direct read, and
881  * even then there is a window between the GETATTR and the subsequent
882  * READ where the file size could change.  Our preference is simply
883  * to do all reads the application wants, and the server will take
884  * care of managing the end of file boundary.
885  *
886  * This function also eliminates unnecessarily updating the file's
887  * atime locally, as the NFS server sets the file's atime, and this
888  * client must read the updated atime from the server back into its
889  * cache.
890  */
891 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
892 				unsigned long nr_segs, loff_t pos)
893 {
894 	ssize_t retval = -EINVAL;
895 	struct file *file = iocb->ki_filp;
896 	struct address_space *mapping = file->f_mapping;
897 	size_t count;
898 
899 	count = iov_length(iov, nr_segs);
900 	nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
901 
902 	dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
903 		file->f_path.dentry->d_parent->d_name.name,
904 		file->f_path.dentry->d_name.name,
905 		count, (long long) pos);
906 
907 	retval = 0;
908 	if (!count)
909 		goto out;
910 
911 	retval = nfs_sync_mapping(mapping);
912 	if (retval)
913 		goto out;
914 
915 	retval = nfs_direct_read(iocb, iov, nr_segs, pos);
916 	if (retval > 0)
917 		iocb->ki_pos = pos + retval;
918 
919 out:
920 	return retval;
921 }
922 
923 /**
924  * nfs_file_direct_write - file direct write operation for NFS files
925  * @iocb: target I/O control block
926  * @iov: vector of user buffers from which to write data
927  * @nr_segs: size of iov vector
928  * @pos: byte offset in file where writing starts
929  *
930  * We use this function for direct writes instead of calling
931  * generic_file_aio_write() in order to avoid taking the inode
932  * semaphore and updating the i_size.  The NFS server will set
933  * the new i_size and this client must read the updated size
934  * back into its cache.  We let the server do generic write
935  * parameter checking and report problems.
936  *
937  * We eliminate local atime updates, see direct read above.
938  *
939  * We avoid unnecessary page cache invalidations for normal cached
940  * readers of this file.
941  *
942  * Note that O_APPEND is not supported for NFS direct writes, as there
943  * is no atomic O_APPEND write facility in the NFS protocol.
944  */
945 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
946 				unsigned long nr_segs, loff_t pos)
947 {
948 	ssize_t retval = -EINVAL;
949 	struct file *file = iocb->ki_filp;
950 	struct address_space *mapping = file->f_mapping;
951 	size_t count;
952 
953 	count = iov_length(iov, nr_segs);
954 	nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
955 
956 	dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
957 		file->f_path.dentry->d_parent->d_name.name,
958 		file->f_path.dentry->d_name.name,
959 		count, (long long) pos);
960 
961 	retval = generic_write_checks(file, &pos, &count, 0);
962 	if (retval)
963 		goto out;
964 
965 	retval = -EINVAL;
966 	if ((ssize_t) count < 0)
967 		goto out;
968 	retval = 0;
969 	if (!count)
970 		goto out;
971 
972 	retval = nfs_sync_mapping(mapping);
973 	if (retval)
974 		goto out;
975 
976 	retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
977 
978 	if (retval > 0)
979 		iocb->ki_pos = pos + retval;
980 
981 out:
982 	return retval;
983 }
984 
985 /**
986  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
987  *
988  */
989 int __init nfs_init_directcache(void)
990 {
991 	nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
992 						sizeof(struct nfs_direct_req),
993 						0, (SLAB_RECLAIM_ACCOUNT|
994 							SLAB_MEM_SPREAD),
995 						NULL);
996 	if (nfs_direct_cachep == NULL)
997 		return -ENOMEM;
998 
999 	return 0;
1000 }
1001 
1002 /**
1003  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1004  *
1005  */
1006 void nfs_destroy_directcache(void)
1007 {
1008 	kmem_cache_destroy(nfs_direct_cachep);
1009 }
1010