Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6/mini2440.git] / fs / nfs / direct.c
blob08f6b040d289d9ecb26979342bdf478db3c5a0b8
1 /*
2 * linux/fs/nfs/direct.c
4 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
6 * High-performance uncached I/O for the Linux NFS client
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.
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.
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.
29 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
30 * help from Andrew Morton.
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
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>
48 #include <linux/nfs_fs.h>
49 #include <linux/nfs_page.h>
50 #include <linux/sunrpc/clnt.h>
52 #include <asm/system.h>
53 #include <asm/uaccess.h>
54 #include <asm/atomic.h>
56 #include "internal.h"
57 #include "iostat.h"
59 #define NFSDBG_FACILITY NFSDBG_VFS
61 static struct kmem_cache *nfs_direct_cachep;
64 * This represents a set of asynchronous requests that we're waiting on
66 struct nfs_direct_req {
67 struct kref kref; /* release manager */
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 */
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 */
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 */
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;
93 static inline void get_dreq(struct nfs_direct_req *dreq)
95 atomic_inc(&dreq->io_count);
98 static inline int put_dreq(struct nfs_direct_req *dreq)
100 return atomic_dec_and_test(&dreq->io_count);
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
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.
116 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
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);
122 return -EINVAL;
125 static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
127 unsigned int npages;
128 unsigned int i;
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);
141 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
143 unsigned int i;
144 for (i = 0; i < npages; i++)
145 page_cache_release(pages[i]);
148 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
150 struct nfs_direct_req *dreq;
152 dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
153 if (!dreq)
154 return NULL;
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;
168 return dreq;
171 static void nfs_direct_req_free(struct kref *kref)
173 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
175 if (dreq->ctx != NULL)
176 put_nfs_open_context(dreq->ctx);
177 kmem_cache_free(nfs_direct_cachep, dreq);
180 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
182 kref_put(&dreq->kref, nfs_direct_req_free);
186 * Collects and returns the final error value/byte-count.
188 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
190 ssize_t result = -EIOCBQUEUED;
192 /* Async requests don't wait here */
193 if (dreq->iocb)
194 goto out;
196 result = wait_for_completion_killable(&dreq->completion);
198 if (!result)
199 result = dreq->error;
200 if (!result)
201 result = dreq->count;
203 out:
204 return (ssize_t) result;
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.
211 static void nfs_direct_complete(struct nfs_direct_req *dreq)
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);
219 complete_all(&dreq->completion);
221 nfs_direct_req_release(dreq);
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).
229 static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
231 struct nfs_read_data *data = calldata;
233 nfs_readpage_result(task, data);
236 static void nfs_direct_read_release(void *calldata)
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;
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);
254 nfs_direct_release_pages(data->pagevec, data->npages);
256 if (put_dreq(dreq))
257 nfs_direct_complete(dreq);
258 nfs_readdata_release(calldata);
261 static const struct rpc_call_ops nfs_read_direct_ops = {
262 .rpc_call_done = nfs_direct_read_result,
263 .rpc_release = nfs_direct_read_release,
267 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
268 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
269 * bail and stop sending more reads. Read length accounting is
270 * handled automatically by nfs_direct_read_result(). Otherwise, if
271 * no requests have been sent, just return an error.
273 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
274 const struct iovec *iov,
275 loff_t pos)
277 struct nfs_open_context *ctx = dreq->ctx;
278 struct inode *inode = ctx->path.dentry->d_inode;
279 unsigned long user_addr = (unsigned long)iov->iov_base;
280 size_t count = iov->iov_len;
281 size_t rsize = NFS_SERVER(inode)->rsize;
282 struct rpc_task *task;
283 struct rpc_message msg = {
284 .rpc_cred = ctx->cred,
286 struct rpc_task_setup task_setup_data = {
287 .rpc_client = NFS_CLIENT(inode),
288 .rpc_message = &msg,
289 .callback_ops = &nfs_read_direct_ops,
290 .workqueue = nfsiod_workqueue,
291 .flags = RPC_TASK_ASYNC,
293 unsigned int pgbase;
294 int result;
295 ssize_t started = 0;
297 do {
298 struct nfs_read_data *data;
299 size_t bytes;
301 pgbase = user_addr & ~PAGE_MASK;
302 bytes = min(rsize,count);
304 result = -ENOMEM;
305 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
306 if (unlikely(!data))
307 break;
309 down_read(&current->mm->mmap_sem);
310 result = get_user_pages(current, current->mm, user_addr,
311 data->npages, 1, 0, data->pagevec, NULL);
312 up_read(&current->mm->mmap_sem);
313 if (result < 0) {
314 nfs_readdata_release(data);
315 break;
317 if ((unsigned)result < data->npages) {
318 bytes = result * PAGE_SIZE;
319 if (bytes <= pgbase) {
320 nfs_direct_release_pages(data->pagevec, result);
321 nfs_readdata_release(data);
322 break;
324 bytes -= pgbase;
325 data->npages = result;
328 get_dreq(dreq);
330 data->req = (struct nfs_page *) dreq;
331 data->inode = inode;
332 data->cred = msg.rpc_cred;
333 data->args.fh = NFS_FH(inode);
334 data->args.context = get_nfs_open_context(ctx);
335 data->args.offset = pos;
336 data->args.pgbase = pgbase;
337 data->args.pages = data->pagevec;
338 data->args.count = bytes;
339 data->res.fattr = &data->fattr;
340 data->res.eof = 0;
341 data->res.count = bytes;
342 msg.rpc_argp = &data->args;
343 msg.rpc_resp = &data->res;
345 task_setup_data.task = &data->task;
346 task_setup_data.callback_data = data;
347 NFS_PROTO(inode)->read_setup(data, &msg);
349 task = rpc_run_task(&task_setup_data);
350 if (IS_ERR(task))
351 break;
352 rpc_put_task(task);
354 dprintk("NFS: %5u initiated direct read call "
355 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
356 data->task.tk_pid,
357 inode->i_sb->s_id,
358 (long long)NFS_FILEID(inode),
359 bytes,
360 (unsigned long long)data->args.offset);
362 started += bytes;
363 user_addr += bytes;
364 pos += bytes;
365 /* FIXME: Remove this unnecessary math from final patch */
366 pgbase += bytes;
367 pgbase &= ~PAGE_MASK;
368 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
370 count -= bytes;
371 } while (count != 0);
373 if (started)
374 return started;
375 return result < 0 ? (ssize_t) result : -EFAULT;
378 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
379 const struct iovec *iov,
380 unsigned long nr_segs,
381 loff_t pos)
383 ssize_t result = -EINVAL;
384 size_t requested_bytes = 0;
385 unsigned long seg;
387 get_dreq(dreq);
389 for (seg = 0; seg < nr_segs; seg++) {
390 const struct iovec *vec = &iov[seg];
391 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
392 if (result < 0)
393 break;
394 requested_bytes += result;
395 if ((size_t)result < vec->iov_len)
396 break;
397 pos += vec->iov_len;
400 if (put_dreq(dreq))
401 nfs_direct_complete(dreq);
403 if (requested_bytes != 0)
404 return 0;
406 if (result < 0)
407 return result;
408 return -EIO;
411 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
412 unsigned long nr_segs, loff_t pos)
414 ssize_t result = 0;
415 struct inode *inode = iocb->ki_filp->f_mapping->host;
416 struct nfs_direct_req *dreq;
418 dreq = nfs_direct_req_alloc();
419 if (!dreq)
420 return -ENOMEM;
422 dreq->inode = inode;
423 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
424 if (!is_sync_kiocb(iocb))
425 dreq->iocb = iocb;
427 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
428 if (!result)
429 result = nfs_direct_wait(dreq);
430 nfs_direct_req_release(dreq);
432 return result;
435 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
437 while (!list_empty(&dreq->rewrite_list)) {
438 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
439 list_del(&data->pages);
440 nfs_direct_release_pages(data->pagevec, data->npages);
441 nfs_writedata_release(data);
445 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
446 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
448 struct inode *inode = dreq->inode;
449 struct list_head *p;
450 struct nfs_write_data *data;
451 struct rpc_task *task;
452 struct rpc_message msg = {
453 .rpc_cred = dreq->ctx->cred,
455 struct rpc_task_setup task_setup_data = {
456 .rpc_client = NFS_CLIENT(inode),
457 .callback_ops = &nfs_write_direct_ops,
458 .workqueue = nfsiod_workqueue,
459 .flags = RPC_TASK_ASYNC,
462 dreq->count = 0;
463 get_dreq(dreq);
465 list_for_each(p, &dreq->rewrite_list) {
466 data = list_entry(p, struct nfs_write_data, pages);
468 get_dreq(dreq);
470 /* Use stable writes */
471 data->args.stable = NFS_FILE_SYNC;
474 * Reset data->res.
476 nfs_fattr_init(&data->fattr);
477 data->res.count = data->args.count;
478 memset(&data->verf, 0, sizeof(data->verf));
481 * Reuse data->task; data->args should not have changed
482 * since the original request was sent.
484 task_setup_data.task = &data->task;
485 task_setup_data.callback_data = data;
486 msg.rpc_argp = &data->args;
487 msg.rpc_resp = &data->res;
488 NFS_PROTO(inode)->write_setup(data, &msg);
491 * We're called via an RPC callback, so BKL is already held.
493 task = rpc_run_task(&task_setup_data);
494 if (!IS_ERR(task))
495 rpc_put_task(task);
497 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
498 data->task.tk_pid,
499 inode->i_sb->s_id,
500 (long long)NFS_FILEID(inode),
501 data->args.count,
502 (unsigned long long)data->args.offset);
505 if (put_dreq(dreq))
506 nfs_direct_write_complete(dreq, inode);
509 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
511 struct nfs_write_data *data = calldata;
513 /* Call the NFS version-specific code */
514 NFS_PROTO(data->inode)->commit_done(task, data);
517 static void nfs_direct_commit_release(void *calldata)
519 struct nfs_write_data *data = calldata;
520 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
521 int status = data->task.tk_status;
523 if (status < 0) {
524 dprintk("NFS: %5u commit failed with error %d.\n",
525 data->task.tk_pid, status);
526 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
527 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
528 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
529 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
532 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
533 nfs_direct_write_complete(dreq, data->inode);
534 nfs_commitdata_release(calldata);
537 static const struct rpc_call_ops nfs_commit_direct_ops = {
538 .rpc_call_done = nfs_direct_commit_result,
539 .rpc_release = nfs_direct_commit_release,
542 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
544 struct nfs_write_data *data = dreq->commit_data;
545 struct rpc_task *task;
546 struct rpc_message msg = {
547 .rpc_argp = &data->args,
548 .rpc_resp = &data->res,
549 .rpc_cred = dreq->ctx->cred,
551 struct rpc_task_setup task_setup_data = {
552 .task = &data->task,
553 .rpc_client = NFS_CLIENT(dreq->inode),
554 .rpc_message = &msg,
555 .callback_ops = &nfs_commit_direct_ops,
556 .callback_data = data,
557 .workqueue = nfsiod_workqueue,
558 .flags = RPC_TASK_ASYNC,
561 data->inode = dreq->inode;
562 data->cred = msg.rpc_cred;
564 data->args.fh = NFS_FH(data->inode);
565 data->args.offset = 0;
566 data->args.count = 0;
567 data->args.context = get_nfs_open_context(dreq->ctx);
568 data->res.count = 0;
569 data->res.fattr = &data->fattr;
570 data->res.verf = &data->verf;
572 NFS_PROTO(data->inode)->commit_setup(data, &msg);
574 /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
575 dreq->commit_data = NULL;
577 dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
579 task = rpc_run_task(&task_setup_data);
580 if (!IS_ERR(task))
581 rpc_put_task(task);
584 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
586 int flags = dreq->flags;
588 dreq->flags = 0;
589 switch (flags) {
590 case NFS_ODIRECT_DO_COMMIT:
591 nfs_direct_commit_schedule(dreq);
592 break;
593 case NFS_ODIRECT_RESCHED_WRITES:
594 nfs_direct_write_reschedule(dreq);
595 break;
596 default:
597 if (dreq->commit_data != NULL)
598 nfs_commit_free(dreq->commit_data);
599 nfs_direct_free_writedata(dreq);
600 nfs_zap_mapping(inode, inode->i_mapping);
601 nfs_direct_complete(dreq);
605 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
607 dreq->commit_data = nfs_commitdata_alloc();
608 if (dreq->commit_data != NULL)
609 dreq->commit_data->req = (struct nfs_page *) dreq;
611 #else
612 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
614 dreq->commit_data = NULL;
617 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
619 nfs_direct_free_writedata(dreq);
620 nfs_zap_mapping(inode, inode->i_mapping);
621 nfs_direct_complete(dreq);
623 #endif
625 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
627 struct nfs_write_data *data = calldata;
629 if (nfs_writeback_done(task, data) != 0)
630 return;
634 * NB: Return the value of the first error return code. Subsequent
635 * errors after the first one are ignored.
637 static void nfs_direct_write_release(void *calldata)
639 struct nfs_write_data *data = calldata;
640 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
641 int status = data->task.tk_status;
643 spin_lock(&dreq->lock);
645 if (unlikely(status < 0)) {
646 /* An error has occurred, so we should not commit */
647 dreq->flags = 0;
648 dreq->error = status;
650 if (unlikely(dreq->error != 0))
651 goto out_unlock;
653 dreq->count += data->res.count;
655 if (data->res.verf->committed != NFS_FILE_SYNC) {
656 switch (dreq->flags) {
657 case 0:
658 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
659 dreq->flags = NFS_ODIRECT_DO_COMMIT;
660 break;
661 case NFS_ODIRECT_DO_COMMIT:
662 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
663 dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
664 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
668 out_unlock:
669 spin_unlock(&dreq->lock);
671 if (put_dreq(dreq))
672 nfs_direct_write_complete(dreq, data->inode);
675 static const struct rpc_call_ops nfs_write_direct_ops = {
676 .rpc_call_done = nfs_direct_write_result,
677 .rpc_release = nfs_direct_write_release,
681 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
682 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
683 * bail and stop sending more writes. Write length accounting is
684 * handled automatically by nfs_direct_write_result(). Otherwise, if
685 * no requests have been sent, just return an error.
687 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
688 const struct iovec *iov,
689 loff_t pos, int sync)
691 struct nfs_open_context *ctx = dreq->ctx;
692 struct inode *inode = ctx->path.dentry->d_inode;
693 unsigned long user_addr = (unsigned long)iov->iov_base;
694 size_t count = iov->iov_len;
695 struct rpc_task *task;
696 struct rpc_message msg = {
697 .rpc_cred = ctx->cred,
699 struct rpc_task_setup task_setup_data = {
700 .rpc_client = NFS_CLIENT(inode),
701 .rpc_message = &msg,
702 .callback_ops = &nfs_write_direct_ops,
703 .workqueue = nfsiod_workqueue,
704 .flags = RPC_TASK_ASYNC,
706 size_t wsize = NFS_SERVER(inode)->wsize;
707 unsigned int pgbase;
708 int result;
709 ssize_t started = 0;
711 do {
712 struct nfs_write_data *data;
713 size_t bytes;
715 pgbase = user_addr & ~PAGE_MASK;
716 bytes = min(wsize,count);
718 result = -ENOMEM;
719 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
720 if (unlikely(!data))
721 break;
723 down_read(&current->mm->mmap_sem);
724 result = get_user_pages(current, current->mm, user_addr,
725 data->npages, 0, 0, data->pagevec, NULL);
726 up_read(&current->mm->mmap_sem);
727 if (result < 0) {
728 nfs_writedata_release(data);
729 break;
731 if ((unsigned)result < data->npages) {
732 bytes = result * PAGE_SIZE;
733 if (bytes <= pgbase) {
734 nfs_direct_release_pages(data->pagevec, result);
735 nfs_writedata_release(data);
736 break;
738 bytes -= pgbase;
739 data->npages = result;
742 get_dreq(dreq);
744 list_move_tail(&data->pages, &dreq->rewrite_list);
746 data->req = (struct nfs_page *) dreq;
747 data->inode = inode;
748 data->cred = msg.rpc_cred;
749 data->args.fh = NFS_FH(inode);
750 data->args.context = get_nfs_open_context(ctx);
751 data->args.offset = pos;
752 data->args.pgbase = pgbase;
753 data->args.pages = data->pagevec;
754 data->args.count = bytes;
755 data->args.stable = sync;
756 data->res.fattr = &data->fattr;
757 data->res.count = bytes;
758 data->res.verf = &data->verf;
760 task_setup_data.task = &data->task;
761 task_setup_data.callback_data = data;
762 msg.rpc_argp = &data->args;
763 msg.rpc_resp = &data->res;
764 NFS_PROTO(inode)->write_setup(data, &msg);
766 task = rpc_run_task(&task_setup_data);
767 if (IS_ERR(task))
768 break;
769 rpc_put_task(task);
771 dprintk("NFS: %5u initiated direct write call "
772 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
773 data->task.tk_pid,
774 inode->i_sb->s_id,
775 (long long)NFS_FILEID(inode),
776 bytes,
777 (unsigned long long)data->args.offset);
779 started += bytes;
780 user_addr += bytes;
781 pos += bytes;
783 /* FIXME: Remove this useless math from the final patch */
784 pgbase += bytes;
785 pgbase &= ~PAGE_MASK;
786 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
788 count -= bytes;
789 } while (count != 0);
791 if (started)
792 return started;
793 return result < 0 ? (ssize_t) result : -EFAULT;
796 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
797 const struct iovec *iov,
798 unsigned long nr_segs,
799 loff_t pos, int sync)
801 ssize_t result = 0;
802 size_t requested_bytes = 0;
803 unsigned long seg;
805 get_dreq(dreq);
807 for (seg = 0; seg < nr_segs; seg++) {
808 const struct iovec *vec = &iov[seg];
809 result = nfs_direct_write_schedule_segment(dreq, vec,
810 pos, sync);
811 if (result < 0)
812 break;
813 requested_bytes += result;
814 if ((size_t)result < vec->iov_len)
815 break;
816 pos += vec->iov_len;
819 if (put_dreq(dreq))
820 nfs_direct_write_complete(dreq, dreq->inode);
822 if (requested_bytes != 0)
823 return 0;
825 if (result < 0)
826 return result;
827 return -EIO;
830 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
831 unsigned long nr_segs, loff_t pos,
832 size_t count)
834 ssize_t result = 0;
835 struct inode *inode = iocb->ki_filp->f_mapping->host;
836 struct nfs_direct_req *dreq;
837 size_t wsize = NFS_SERVER(inode)->wsize;
838 int sync = NFS_UNSTABLE;
840 dreq = nfs_direct_req_alloc();
841 if (!dreq)
842 return -ENOMEM;
843 nfs_alloc_commit_data(dreq);
845 if (dreq->commit_data == NULL || count < wsize)
846 sync = NFS_FILE_SYNC;
848 dreq->inode = inode;
849 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
850 if (!is_sync_kiocb(iocb))
851 dreq->iocb = iocb;
853 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
854 if (!result)
855 result = nfs_direct_wait(dreq);
856 nfs_direct_req_release(dreq);
858 return result;
862 * nfs_file_direct_read - file direct read operation for NFS files
863 * @iocb: target I/O control block
864 * @iov: vector of user buffers into which to read data
865 * @nr_segs: size of iov vector
866 * @pos: byte offset in file where reading starts
868 * We use this function for direct reads instead of calling
869 * generic_file_aio_read() in order to avoid gfar's check to see if
870 * the request starts before the end of the file. For that check
871 * to work, we must generate a GETATTR before each direct read, and
872 * even then there is a window between the GETATTR and the subsequent
873 * READ where the file size could change. Our preference is simply
874 * to do all reads the application wants, and the server will take
875 * care of managing the end of file boundary.
877 * This function also eliminates unnecessarily updating the file's
878 * atime locally, as the NFS server sets the file's atime, and this
879 * client must read the updated atime from the server back into its
880 * cache.
882 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
883 unsigned long nr_segs, loff_t pos)
885 ssize_t retval = -EINVAL;
886 struct file *file = iocb->ki_filp;
887 struct address_space *mapping = file->f_mapping;
888 size_t count;
890 count = iov_length(iov, nr_segs);
891 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
893 dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
894 file->f_path.dentry->d_parent->d_name.name,
895 file->f_path.dentry->d_name.name,
896 count, (long long) pos);
898 retval = 0;
899 if (!count)
900 goto out;
902 retval = nfs_sync_mapping(mapping);
903 if (retval)
904 goto out;
906 retval = nfs_direct_read(iocb, iov, nr_segs, pos);
907 if (retval > 0)
908 iocb->ki_pos = pos + retval;
910 out:
911 return retval;
915 * nfs_file_direct_write - file direct write operation for NFS files
916 * @iocb: target I/O control block
917 * @iov: vector of user buffers from which to write data
918 * @nr_segs: size of iov vector
919 * @pos: byte offset in file where writing starts
921 * We use this function for direct writes instead of calling
922 * generic_file_aio_write() in order to avoid taking the inode
923 * semaphore and updating the i_size. The NFS server will set
924 * the new i_size and this client must read the updated size
925 * back into its cache. We let the server do generic write
926 * parameter checking and report problems.
928 * We also avoid an unnecessary invocation of generic_osync_inode(),
929 * as it is fairly meaningless to sync the metadata of an NFS file.
931 * We eliminate local atime updates, see direct read above.
933 * We avoid unnecessary page cache invalidations for normal cached
934 * readers of this file.
936 * Note that O_APPEND is not supported for NFS direct writes, as there
937 * is no atomic O_APPEND write facility in the NFS protocol.
939 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
940 unsigned long nr_segs, loff_t pos)
942 ssize_t retval = -EINVAL;
943 struct file *file = iocb->ki_filp;
944 struct address_space *mapping = file->f_mapping;
945 size_t count;
947 count = iov_length(iov, nr_segs);
948 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
950 dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
951 file->f_path.dentry->d_parent->d_name.name,
952 file->f_path.dentry->d_name.name,
953 count, (long long) pos);
955 retval = generic_write_checks(file, &pos, &count, 0);
956 if (retval)
957 goto out;
959 retval = -EINVAL;
960 if ((ssize_t) count < 0)
961 goto out;
962 retval = 0;
963 if (!count)
964 goto out;
966 retval = nfs_sync_mapping(mapping);
967 if (retval)
968 goto out;
970 retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
972 if (retval > 0)
973 iocb->ki_pos = pos + retval;
975 out:
976 return retval;
980 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
983 int __init nfs_init_directcache(void)
985 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
986 sizeof(struct nfs_direct_req),
987 0, (SLAB_RECLAIM_ACCOUNT|
988 SLAB_MEM_SPREAD),
989 NULL);
990 if (nfs_direct_cachep == NULL)
991 return -ENOMEM;
993 return 0;
997 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1000 void nfs_destroy_directcache(void)
1002 kmem_cache_destroy(nfs_direct_cachep);