mm-only debug patch...
[mmotm.git] / fs / nfs / direct.c
blob6c3210099d518406b8453296312d759396fbae41
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_free(data);
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,
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.
276 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
277 const struct iovec *iov,
278 loff_t pos)
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,
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,
296 unsigned int pgbase;
297 int result;
298 ssize_t started = 0;
300 do {
301 struct nfs_read_data *data;
302 size_t bytes;
304 pgbase = user_addr & ~PAGE_MASK;
305 bytes = min(rsize,count);
307 result = -ENOMEM;
308 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
309 if (unlikely(!data))
310 break;
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;
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;
327 bytes -= pgbase;
328 data->npages = result;
331 get_dreq(dreq);
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;
348 task_setup_data.task = &data->task;
349 task_setup_data.callback_data = data;
350 NFS_PROTO(inode)->read_setup(data, &msg);
352 task = rpc_run_task(&task_setup_data);
353 if (IS_ERR(task))
354 break;
355 rpc_put_task(task);
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);
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));
373 count -= bytes;
374 } while (count != 0);
376 if (started)
377 return started;
378 return result < 0 ? (ssize_t) result : -EFAULT;
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)
386 ssize_t result = -EINVAL;
387 size_t requested_bytes = 0;
388 unsigned long seg;
390 get_dreq(dreq);
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;
403 if (put_dreq(dreq))
404 nfs_direct_complete(dreq);
406 if (requested_bytes != 0)
407 return 0;
409 if (result < 0)
410 return result;
411 return -EIO;
414 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
415 unsigned long nr_segs, loff_t pos)
417 ssize_t result = 0;
418 struct inode *inode = iocb->ki_filp->f_mapping->host;
419 struct nfs_direct_req *dreq;
421 dreq = nfs_direct_req_alloc();
422 if (!dreq)
423 return -ENOMEM;
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;
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);
435 return result;
438 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
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);
448 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
449 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
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,
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,
465 dreq->count = 0;
466 get_dreq(dreq);
468 list_for_each(p, &dreq->rewrite_list) {
469 data = list_entry(p, struct nfs_write_data, pages);
471 get_dreq(dreq);
473 /* Use stable writes */
474 data->args.stable = NFS_FILE_SYNC;
477 * Reset data->res.
479 nfs_fattr_init(&data->fattr);
480 data->res.count = data->args.count;
481 memset(&data->verf, 0, sizeof(data->verf));
484 * Reuse data->task; data->args should not have changed
485 * since the original request was sent.
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);
494 * We're called via an RPC callback, so BKL is already held.
496 task = rpc_run_task(&task_setup_data);
497 if (!IS_ERR(task))
498 rpc_put_task(task);
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);
508 if (put_dreq(dreq))
509 nfs_direct_write_complete(dreq, inode);
512 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
514 struct nfs_write_data *data = calldata;
516 /* Call the NFS version-specific code */
517 NFS_PROTO(data->inode)->commit_done(task, data);
520 static void nfs_direct_commit_release(void *calldata)
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;
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;
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);
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,
548 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
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,
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,
567 data->inode = dreq->inode;
568 data->cred = msg.rpc_cred;
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;
578 NFS_PROTO(data->inode)->commit_setup(data, &msg);
580 /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
581 dreq->commit_data = NULL;
583 dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
585 task = rpc_run_task(&task_setup_data);
586 if (!IS_ERR(task))
587 rpc_put_task(task);
590 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
592 int flags = dreq->flags;
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);
611 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
613 dreq->commit_data = nfs_commitdata_alloc();
614 if (dreq->commit_data != NULL)
615 dreq->commit_data->req = (struct nfs_page *) dreq;
617 #else
618 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
620 dreq->commit_data = NULL;
623 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
625 nfs_direct_free_writedata(dreq);
626 nfs_zap_mapping(inode, inode->i_mapping);
627 nfs_direct_complete(dreq);
629 #endif
631 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
633 struct nfs_write_data *data = calldata;
635 if (nfs_writeback_done(task, data) != 0)
636 return;
640 * NB: Return the value of the first error return code. Subsequent
641 * errors after the first one are ignored.
643 static void nfs_direct_write_release(void *calldata)
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;
649 spin_lock(&dreq->lock);
651 if (unlikely(status < 0)) {
652 /* An error has occurred, so we should not commit */
653 dreq->flags = 0;
654 dreq->error = status;
656 if (unlikely(dreq->error != 0))
657 goto out_unlock;
659 dreq->count += data->res.count;
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;
674 out_unlock:
675 spin_unlock(&dreq->lock);
677 if (put_dreq(dreq))
678 nfs_direct_write_complete(dreq, data->inode);
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,
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.
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)
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,
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,
715 size_t wsize = NFS_SERVER(inode)->wsize;
716 unsigned int pgbase;
717 int result;
718 ssize_t started = 0;
720 do {
721 struct nfs_write_data *data;
722 size_t bytes;
724 pgbase = user_addr & ~PAGE_MASK;
725 bytes = min(wsize,count);
727 result = -ENOMEM;
728 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
729 if (unlikely(!data))
730 break;
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;
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;
747 bytes -= pgbase;
748 data->npages = result;
751 get_dreq(dreq);
753 list_move_tail(&data->pages, &dreq->rewrite_list);
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;
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);
775 task = rpc_run_task(&task_setup_data);
776 if (IS_ERR(task))
777 break;
778 rpc_put_task(task);
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);
788 started += bytes;
789 user_addr += bytes;
790 pos += bytes;
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));
797 count -= bytes;
798 } while (count != 0);
800 if (started)
801 return started;
802 return result < 0 ? (ssize_t) result : -EFAULT;
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)
810 ssize_t result = 0;
811 size_t requested_bytes = 0;
812 unsigned long seg;
814 get_dreq(dreq);
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;
828 if (put_dreq(dreq))
829 nfs_direct_write_complete(dreq, dreq->inode);
831 if (requested_bytes != 0)
832 return 0;
834 if (result < 0)
835 return result;
836 return -EIO;
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)
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;
849 dreq = nfs_direct_req_alloc();
850 if (!dreq)
851 return -ENOMEM;
852 nfs_alloc_commit_data(dreq);
854 if (dreq->commit_data == NULL || count < wsize)
855 sync = NFS_FILE_SYNC;
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;
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);
867 return result;
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
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.
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.
891 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
892 unsigned long nr_segs, loff_t pos)
894 ssize_t retval = -EINVAL;
895 struct file *file = iocb->ki_filp;
896 struct address_space *mapping = file->f_mapping;
897 size_t count;
899 count = iov_length(iov, nr_segs);
900 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
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);
907 retval = 0;
908 if (!count)
909 goto out;
911 retval = nfs_sync_mapping(mapping);
912 if (retval)
913 goto out;
915 retval = nfs_direct_read(iocb, iov, nr_segs, pos);
916 if (retval > 0)
917 iocb->ki_pos = pos + retval;
919 out:
920 return retval;
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
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.
937 * We eliminate local atime updates, see direct read above.
939 * We avoid unnecessary page cache invalidations for normal cached
940 * readers of this file.
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.
945 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
946 unsigned long nr_segs, loff_t pos)
948 ssize_t retval = -EINVAL;
949 struct file *file = iocb->ki_filp;
950 struct address_space *mapping = file->f_mapping;
951 size_t count;
953 count = iov_length(iov, nr_segs);
954 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
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);
961 retval = generic_write_checks(file, &pos, &count, 0);
962 if (retval)
963 goto out;
965 retval = -EINVAL;
966 if ((ssize_t) count < 0)
967 goto out;
968 retval = 0;
969 if (!count)
970 goto out;
972 retval = nfs_sync_mapping(mapping);
973 if (retval)
974 goto out;
976 retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
978 if (retval > 0)
979 iocb->ki_pos = pos + retval;
981 out:
982 return retval;
986 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
989 int __init nfs_init_directcache(void)
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;
999 return 0;
1003 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1006 void nfs_destroy_directcache(void)
1008 kmem_cache_destroy(nfs_direct_cachep);