ACPI: thinkpad-acpi: keep track of module state
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / nfs / direct.c
blobfcf4d384610e1a916cebf2f5c9c3f958f8c54b0b
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_interruptible(&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;
232 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
234 if (nfs_readpage_result(task, data) != 0)
235 return;
237 spin_lock(&dreq->lock);
238 if (unlikely(task->tk_status < 0)) {
239 dreq->error = task->tk_status;
240 spin_unlock(&dreq->lock);
241 } else {
242 dreq->count += data->res.count;
243 spin_unlock(&dreq->lock);
244 nfs_direct_dirty_pages(data->pagevec,
245 data->args.pgbase,
246 data->res.count);
248 nfs_direct_release_pages(data->pagevec, data->npages);
250 if (put_dreq(dreq))
251 nfs_direct_complete(dreq);
254 static const struct rpc_call_ops nfs_read_direct_ops = {
255 .rpc_call_done = nfs_direct_read_result,
256 .rpc_release = nfs_readdata_release,
260 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
261 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
262 * bail and stop sending more reads. Read length accounting is
263 * handled automatically by nfs_direct_read_result(). Otherwise, if
264 * no requests have been sent, just return an error.
266 static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos)
268 struct nfs_open_context *ctx = dreq->ctx;
269 struct inode *inode = ctx->path.dentry->d_inode;
270 size_t rsize = NFS_SERVER(inode)->rsize;
271 unsigned int pgbase;
272 int result;
273 ssize_t started = 0;
275 get_dreq(dreq);
277 do {
278 struct nfs_read_data *data;
279 size_t bytes;
281 pgbase = user_addr & ~PAGE_MASK;
282 bytes = min(rsize,count);
284 result = -ENOMEM;
285 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
286 if (unlikely(!data))
287 break;
289 down_read(&current->mm->mmap_sem);
290 result = get_user_pages(current, current->mm, user_addr,
291 data->npages, 1, 0, data->pagevec, NULL);
292 up_read(&current->mm->mmap_sem);
293 if (result < 0) {
294 nfs_readdata_release(data);
295 break;
297 if ((unsigned)result < data->npages) {
298 bytes = result * PAGE_SIZE;
299 if (bytes <= pgbase) {
300 nfs_direct_release_pages(data->pagevec, result);
301 nfs_readdata_release(data);
302 break;
304 bytes -= pgbase;
305 data->npages = result;
308 get_dreq(dreq);
310 data->req = (struct nfs_page *) dreq;
311 data->inode = inode;
312 data->cred = ctx->cred;
313 data->args.fh = NFS_FH(inode);
314 data->args.context = ctx;
315 data->args.offset = pos;
316 data->args.pgbase = pgbase;
317 data->args.pages = data->pagevec;
318 data->args.count = bytes;
319 data->res.fattr = &data->fattr;
320 data->res.eof = 0;
321 data->res.count = bytes;
323 rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
324 &nfs_read_direct_ops, data);
325 NFS_PROTO(inode)->read_setup(data);
327 data->task.tk_cookie = (unsigned long) inode;
329 rpc_execute(&data->task);
331 dprintk("NFS: %5u initiated direct read call "
332 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
333 data->task.tk_pid,
334 inode->i_sb->s_id,
335 (long long)NFS_FILEID(inode),
336 bytes,
337 (unsigned long long)data->args.offset);
339 started += bytes;
340 user_addr += bytes;
341 pos += bytes;
342 /* FIXME: Remove this unnecessary math from final patch */
343 pgbase += bytes;
344 pgbase &= ~PAGE_MASK;
345 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
347 count -= bytes;
348 } while (count != 0);
350 if (put_dreq(dreq))
351 nfs_direct_complete(dreq);
353 if (started)
354 return 0;
355 return result < 0 ? (ssize_t) result : -EFAULT;
358 static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
360 ssize_t result = 0;
361 sigset_t oldset;
362 struct inode *inode = iocb->ki_filp->f_mapping->host;
363 struct rpc_clnt *clnt = NFS_CLIENT(inode);
364 struct nfs_direct_req *dreq;
366 dreq = nfs_direct_req_alloc();
367 if (!dreq)
368 return -ENOMEM;
370 dreq->inode = inode;
371 dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
372 if (!is_sync_kiocb(iocb))
373 dreq->iocb = iocb;
375 nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);
376 rpc_clnt_sigmask(clnt, &oldset);
377 result = nfs_direct_read_schedule(dreq, user_addr, count, pos);
378 if (!result)
379 result = nfs_direct_wait(dreq);
380 rpc_clnt_sigunmask(clnt, &oldset);
381 nfs_direct_req_release(dreq);
383 return result;
386 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
388 while (!list_empty(&dreq->rewrite_list)) {
389 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
390 list_del(&data->pages);
391 nfs_direct_release_pages(data->pagevec, data->npages);
392 nfs_writedata_release(data);
396 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
397 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
399 struct inode *inode = dreq->inode;
400 struct list_head *p;
401 struct nfs_write_data *data;
403 dreq->count = 0;
404 get_dreq(dreq);
406 list_for_each(p, &dreq->rewrite_list) {
407 data = list_entry(p, struct nfs_write_data, pages);
409 get_dreq(dreq);
412 * Reset data->res.
414 nfs_fattr_init(&data->fattr);
415 data->res.count = data->args.count;
416 memset(&data->verf, 0, sizeof(data->verf));
419 * Reuse data->task; data->args should not have changed
420 * since the original request was sent.
422 rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
423 &nfs_write_direct_ops, data);
424 NFS_PROTO(inode)->write_setup(data, FLUSH_STABLE);
426 data->task.tk_priority = RPC_PRIORITY_NORMAL;
427 data->task.tk_cookie = (unsigned long) inode;
430 * We're called via an RPC callback, so BKL is already held.
432 rpc_execute(&data->task);
434 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
435 data->task.tk_pid,
436 inode->i_sb->s_id,
437 (long long)NFS_FILEID(inode),
438 data->args.count,
439 (unsigned long long)data->args.offset);
442 if (put_dreq(dreq))
443 nfs_direct_write_complete(dreq, inode);
446 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
448 struct nfs_write_data *data = calldata;
449 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
451 /* Call the NFS version-specific code */
452 if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
453 return;
454 if (unlikely(task->tk_status < 0)) {
455 dprintk("NFS: %5u commit failed with error %d.\n",
456 task->tk_pid, task->tk_status);
457 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
458 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
459 dprintk("NFS: %5u commit verify failed\n", task->tk_pid);
460 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
463 dprintk("NFS: %5u commit returned %d\n", task->tk_pid, task->tk_status);
464 nfs_direct_write_complete(dreq, data->inode);
467 static const struct rpc_call_ops nfs_commit_direct_ops = {
468 .rpc_call_done = nfs_direct_commit_result,
469 .rpc_release = nfs_commit_release,
472 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
474 struct nfs_write_data *data = dreq->commit_data;
476 data->inode = dreq->inode;
477 data->cred = dreq->ctx->cred;
479 data->args.fh = NFS_FH(data->inode);
480 data->args.offset = 0;
481 data->args.count = 0;
482 data->res.count = 0;
483 data->res.fattr = &data->fattr;
484 data->res.verf = &data->verf;
486 rpc_init_task(&data->task, NFS_CLIENT(dreq->inode), RPC_TASK_ASYNC,
487 &nfs_commit_direct_ops, data);
488 NFS_PROTO(data->inode)->commit_setup(data, 0);
490 data->task.tk_priority = RPC_PRIORITY_NORMAL;
491 data->task.tk_cookie = (unsigned long)data->inode;
492 /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
493 dreq->commit_data = NULL;
495 dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
497 rpc_execute(&data->task);
500 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
502 int flags = dreq->flags;
504 dreq->flags = 0;
505 switch (flags) {
506 case NFS_ODIRECT_DO_COMMIT:
507 nfs_direct_commit_schedule(dreq);
508 break;
509 case NFS_ODIRECT_RESCHED_WRITES:
510 nfs_direct_write_reschedule(dreq);
511 break;
512 default:
513 nfs_end_data_update(inode);
514 if (dreq->commit_data != NULL)
515 nfs_commit_free(dreq->commit_data);
516 nfs_direct_free_writedata(dreq);
517 nfs_zap_mapping(inode, inode->i_mapping);
518 nfs_direct_complete(dreq);
522 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
524 dreq->commit_data = nfs_commit_alloc();
525 if (dreq->commit_data != NULL)
526 dreq->commit_data->req = (struct nfs_page *) dreq;
528 #else
529 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
531 dreq->commit_data = NULL;
534 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
536 nfs_end_data_update(inode);
537 nfs_direct_free_writedata(dreq);
538 nfs_zap_mapping(inode, inode->i_mapping);
539 nfs_direct_complete(dreq);
541 #endif
543 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
545 struct nfs_write_data *data = calldata;
546 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
547 int status = task->tk_status;
549 if (nfs_writeback_done(task, data) != 0)
550 return;
552 spin_lock(&dreq->lock);
554 if (unlikely(dreq->error != 0))
555 goto out_unlock;
556 if (unlikely(status < 0)) {
557 /* An error has occured, so we should not commit */
558 dreq->flags = 0;
559 dreq->error = status;
562 dreq->count += data->res.count;
564 if (data->res.verf->committed != NFS_FILE_SYNC) {
565 switch (dreq->flags) {
566 case 0:
567 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
568 dreq->flags = NFS_ODIRECT_DO_COMMIT;
569 break;
570 case NFS_ODIRECT_DO_COMMIT:
571 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
572 dprintk("NFS: %5u write verify failed\n", task->tk_pid);
573 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
577 out_unlock:
578 spin_unlock(&dreq->lock);
582 * NB: Return the value of the first error return code. Subsequent
583 * errors after the first one are ignored.
585 static void nfs_direct_write_release(void *calldata)
587 struct nfs_write_data *data = calldata;
588 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
590 if (put_dreq(dreq))
591 nfs_direct_write_complete(dreq, data->inode);
594 static const struct rpc_call_ops nfs_write_direct_ops = {
595 .rpc_call_done = nfs_direct_write_result,
596 .rpc_release = nfs_direct_write_release,
600 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
601 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
602 * bail and stop sending more writes. Write length accounting is
603 * handled automatically by nfs_direct_write_result(). Otherwise, if
604 * no requests have been sent, just return an error.
606 static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos, int sync)
608 struct nfs_open_context *ctx = dreq->ctx;
609 struct inode *inode = ctx->path.dentry->d_inode;
610 size_t wsize = NFS_SERVER(inode)->wsize;
611 unsigned int pgbase;
612 int result;
613 ssize_t started = 0;
615 get_dreq(dreq);
617 do {
618 struct nfs_write_data *data;
619 size_t bytes;
621 pgbase = user_addr & ~PAGE_MASK;
622 bytes = min(wsize,count);
624 result = -ENOMEM;
625 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
626 if (unlikely(!data))
627 break;
629 down_read(&current->mm->mmap_sem);
630 result = get_user_pages(current, current->mm, user_addr,
631 data->npages, 0, 0, data->pagevec, NULL);
632 up_read(&current->mm->mmap_sem);
633 if (result < 0) {
634 nfs_writedata_release(data);
635 break;
637 if ((unsigned)result < data->npages) {
638 bytes = result * PAGE_SIZE;
639 if (bytes <= pgbase) {
640 nfs_direct_release_pages(data->pagevec, result);
641 nfs_writedata_release(data);
642 break;
644 bytes -= pgbase;
645 data->npages = result;
648 get_dreq(dreq);
650 list_move_tail(&data->pages, &dreq->rewrite_list);
652 data->req = (struct nfs_page *) dreq;
653 data->inode = inode;
654 data->cred = ctx->cred;
655 data->args.fh = NFS_FH(inode);
656 data->args.context = ctx;
657 data->args.offset = pos;
658 data->args.pgbase = pgbase;
659 data->args.pages = data->pagevec;
660 data->args.count = bytes;
661 data->res.fattr = &data->fattr;
662 data->res.count = bytes;
663 data->res.verf = &data->verf;
665 rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
666 &nfs_write_direct_ops, data);
667 NFS_PROTO(inode)->write_setup(data, sync);
669 data->task.tk_priority = RPC_PRIORITY_NORMAL;
670 data->task.tk_cookie = (unsigned long) inode;
672 rpc_execute(&data->task);
674 dprintk("NFS: %5u initiated direct write call "
675 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
676 data->task.tk_pid,
677 inode->i_sb->s_id,
678 (long long)NFS_FILEID(inode),
679 bytes,
680 (unsigned long long)data->args.offset);
682 started += bytes;
683 user_addr += bytes;
684 pos += bytes;
686 /* FIXME: Remove this useless math from the final patch */
687 pgbase += bytes;
688 pgbase &= ~PAGE_MASK;
689 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
691 count -= bytes;
692 } while (count != 0);
694 if (put_dreq(dreq))
695 nfs_direct_write_complete(dreq, inode);
697 if (started)
698 return 0;
699 return result < 0 ? (ssize_t) result : -EFAULT;
702 static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
704 ssize_t result = 0;
705 sigset_t oldset;
706 struct inode *inode = iocb->ki_filp->f_mapping->host;
707 struct rpc_clnt *clnt = NFS_CLIENT(inode);
708 struct nfs_direct_req *dreq;
709 size_t wsize = NFS_SERVER(inode)->wsize;
710 int sync = 0;
712 dreq = nfs_direct_req_alloc();
713 if (!dreq)
714 return -ENOMEM;
715 nfs_alloc_commit_data(dreq);
717 if (dreq->commit_data == NULL || count < wsize)
718 sync = FLUSH_STABLE;
720 dreq->inode = inode;
721 dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
722 if (!is_sync_kiocb(iocb))
723 dreq->iocb = iocb;
725 nfs_add_stats(inode, NFSIOS_DIRECTWRITTENBYTES, count);
727 nfs_begin_data_update(inode);
729 rpc_clnt_sigmask(clnt, &oldset);
730 result = nfs_direct_write_schedule(dreq, user_addr, count, pos, sync);
731 if (!result)
732 result = nfs_direct_wait(dreq);
733 rpc_clnt_sigunmask(clnt, &oldset);
734 nfs_direct_req_release(dreq);
736 return result;
740 * nfs_file_direct_read - file direct read operation for NFS files
741 * @iocb: target I/O control block
742 * @iov: vector of user buffers into which to read data
743 * @nr_segs: size of iov vector
744 * @pos: byte offset in file where reading starts
746 * We use this function for direct reads instead of calling
747 * generic_file_aio_read() in order to avoid gfar's check to see if
748 * the request starts before the end of the file. For that check
749 * to work, we must generate a GETATTR before each direct read, and
750 * even then there is a window between the GETATTR and the subsequent
751 * READ where the file size could change. Our preference is simply
752 * to do all reads the application wants, and the server will take
753 * care of managing the end of file boundary.
755 * This function also eliminates unnecessarily updating the file's
756 * atime locally, as the NFS server sets the file's atime, and this
757 * client must read the updated atime from the server back into its
758 * cache.
760 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
761 unsigned long nr_segs, loff_t pos)
763 ssize_t retval = -EINVAL;
764 struct file *file = iocb->ki_filp;
765 struct address_space *mapping = file->f_mapping;
766 /* XXX: temporary */
767 const char __user *buf = iov[0].iov_base;
768 size_t count = iov[0].iov_len;
770 dprintk("nfs: direct read(%s/%s, %lu@%Ld)\n",
771 file->f_path.dentry->d_parent->d_name.name,
772 file->f_path.dentry->d_name.name,
773 (unsigned long) count, (long long) pos);
775 if (nr_segs != 1)
776 goto out;
778 retval = -EFAULT;
779 if (!access_ok(VERIFY_WRITE, buf, count))
780 goto out;
781 retval = 0;
782 if (!count)
783 goto out;
785 retval = nfs_sync_mapping(mapping);
786 if (retval)
787 goto out;
789 retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos);
790 if (retval > 0)
791 iocb->ki_pos = pos + retval;
793 out:
794 return retval;
798 * nfs_file_direct_write - file direct write operation for NFS files
799 * @iocb: target I/O control block
800 * @iov: vector of user buffers from which to write data
801 * @nr_segs: size of iov vector
802 * @pos: byte offset in file where writing starts
804 * We use this function for direct writes instead of calling
805 * generic_file_aio_write() in order to avoid taking the inode
806 * semaphore and updating the i_size. The NFS server will set
807 * the new i_size and this client must read the updated size
808 * back into its cache. We let the server do generic write
809 * parameter checking and report problems.
811 * We also avoid an unnecessary invocation of generic_osync_inode(),
812 * as it is fairly meaningless to sync the metadata of an NFS file.
814 * We eliminate local atime updates, see direct read above.
816 * We avoid unnecessary page cache invalidations for normal cached
817 * readers of this file.
819 * Note that O_APPEND is not supported for NFS direct writes, as there
820 * is no atomic O_APPEND write facility in the NFS protocol.
822 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
823 unsigned long nr_segs, loff_t pos)
825 ssize_t retval = -EINVAL;
826 struct file *file = iocb->ki_filp;
827 struct address_space *mapping = file->f_mapping;
828 /* XXX: temporary */
829 const char __user *buf = iov[0].iov_base;
830 size_t count = iov[0].iov_len;
832 dprintk("nfs: direct write(%s/%s, %lu@%Ld)\n",
833 file->f_path.dentry->d_parent->d_name.name,
834 file->f_path.dentry->d_name.name,
835 (unsigned long) count, (long long) pos);
837 if (nr_segs != 1)
838 goto out;
840 retval = generic_write_checks(file, &pos, &count, 0);
841 if (retval)
842 goto out;
844 retval = -EINVAL;
845 if ((ssize_t) count < 0)
846 goto out;
847 retval = 0;
848 if (!count)
849 goto out;
851 retval = -EFAULT;
852 if (!access_ok(VERIFY_READ, buf, count))
853 goto out;
855 retval = nfs_sync_mapping(mapping);
856 if (retval)
857 goto out;
859 retval = nfs_direct_write(iocb, (unsigned long) buf, count, pos);
861 if (retval > 0)
862 iocb->ki_pos = pos + retval;
864 out:
865 return retval;
869 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
872 int __init nfs_init_directcache(void)
874 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
875 sizeof(struct nfs_direct_req),
876 0, (SLAB_RECLAIM_ACCOUNT|
877 SLAB_MEM_SPREAD),
878 NULL);
879 if (nfs_direct_cachep == NULL)
880 return -ENOMEM;
882 return 0;
886 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
889 void nfs_destroy_directcache(void)
891 kmem_cache_destroy(nfs_direct_cachep);