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
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>
47 #include <linux/slab.h>
48 #include <linux/task_io_accounting_ops.h>
50 #include <linux/nfs_fs.h>
51 #include <linux/nfs_page.h>
52 #include <linux/sunrpc/clnt.h>
54 #include <asm/uaccess.h>
55 #include <linux/atomic.h>
61 #define NFSDBG_FACILITY NFSDBG_VFS
63 static struct kmem_cache *nfs_direct_cachep;
66 * This represents a set of asynchronous requests that we're waiting on
68 struct nfs_direct_req {
69 struct kref kref; /* release manager */
72 struct nfs_open_context *ctx; /* file open context info */
73 struct nfs_lock_context *l_ctx; /* Lock context info */
74 struct kiocb * iocb; /* controlling i/o request */
75 struct inode * inode; /* target file of i/o */
77 /* completion state */
78 atomic_t io_count; /* i/os we're waiting for */
79 spinlock_t lock; /* protect completion state */
80 ssize_t count, /* bytes actually processed */
81 error; /* any reported error */
82 struct completion completion; /* wait for i/o completion */
85 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
86 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
87 struct work_struct work;
89 #define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
90 #define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
91 struct nfs_writeverf verf; /* unstable write verifier */
94 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
95 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
96 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
97 static void nfs_direct_write_schedule_work(struct work_struct *work);
99 static inline void get_dreq(struct nfs_direct_req *dreq)
101 atomic_inc(&dreq->io_count);
104 static inline int put_dreq(struct nfs_direct_req *dreq)
106 return atomic_dec_and_test(&dreq->io_count);
110 * nfs_direct_IO - NFS address space operation for direct I/O
111 * @rw: direction (read or write)
112 * @iocb: target I/O control block
113 * @iov: array of vectors that define I/O buffer
114 * @pos: offset in file to begin the operation
115 * @nr_segs: size of iovec array
117 * The presence of this routine in the address space ops vector means
118 * the NFS client supports direct I/O. However, we shunt off direct
119 * read and write requests before the VFS gets them, so this method
120 * should never be called.
122 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
124 dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
125 iocb->ki_filp->f_path.dentry->d_name.name,
126 (long long) pos, nr_segs);
131 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
134 for (i = 0; i < npages; i++)
135 page_cache_release(pages[i]);
138 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
139 struct nfs_direct_req *dreq)
141 cinfo->lock = &dreq->lock;
142 cinfo->mds = &dreq->mds_cinfo;
143 cinfo->ds = &dreq->ds_cinfo;
145 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
148 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
150 struct nfs_direct_req *dreq;
152 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
156 kref_init(&dreq->kref);
157 kref_get(&dreq->kref);
158 init_completion(&dreq->completion);
159 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
160 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
161 spin_lock_init(&dreq->lock);
166 static void nfs_direct_req_free(struct kref *kref)
168 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
170 if (dreq->l_ctx != NULL)
171 nfs_put_lock_context(dreq->l_ctx);
172 if (dreq->ctx != NULL)
173 put_nfs_open_context(dreq->ctx);
174 kmem_cache_free(nfs_direct_cachep, dreq);
177 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
179 kref_put(&dreq->kref, nfs_direct_req_free);
183 * Collects and returns the final error value/byte-count.
185 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
187 ssize_t result = -EIOCBQUEUED;
189 /* Async requests don't wait here */
193 result = wait_for_completion_killable(&dreq->completion);
196 result = dreq->error;
198 result = dreq->count;
201 return (ssize_t) result;
205 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
206 * the iocb is still valid here if this is a synchronous request.
208 static void nfs_direct_complete(struct nfs_direct_req *dreq)
211 long res = (long) dreq->error;
213 res = (long) dreq->count;
214 aio_complete(dreq->iocb, res, 0);
216 complete_all(&dreq->completion);
218 nfs_direct_req_release(dreq);
221 static void nfs_direct_readpage_release(struct nfs_page *req)
223 dprintk("NFS: direct read done (%s/%lld %d@%lld)\n",
224 req->wb_context->dentry->d_inode->i_sb->s_id,
225 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
227 (long long)req_offset(req));
228 nfs_release_request(req);
231 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
233 unsigned long bytes = 0;
234 struct nfs_direct_req *dreq = hdr->dreq;
236 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
239 spin_lock(&dreq->lock);
240 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
241 dreq->error = hdr->error;
243 dreq->count += hdr->good_bytes;
244 spin_unlock(&dreq->lock);
246 while (!list_empty(&hdr->pages)) {
247 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
248 struct page *page = req->wb_page;
250 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
251 if (bytes > hdr->good_bytes)
252 zero_user(page, 0, PAGE_SIZE);
253 else if (hdr->good_bytes - bytes < PAGE_SIZE)
254 zero_user_segment(page,
255 hdr->good_bytes & ~PAGE_MASK,
258 if (!PageCompound(page)) {
259 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
260 if (bytes < hdr->good_bytes)
261 set_page_dirty(page);
263 set_page_dirty(page);
265 bytes += req->wb_bytes;
266 nfs_list_remove_request(req);
267 nfs_direct_readpage_release(req);
271 nfs_direct_complete(dreq);
275 static void nfs_read_sync_pgio_error(struct list_head *head)
277 struct nfs_page *req;
279 while (!list_empty(head)) {
280 req = nfs_list_entry(head->next);
281 nfs_list_remove_request(req);
282 nfs_release_request(req);
286 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
291 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
292 .error_cleanup = nfs_read_sync_pgio_error,
293 .init_hdr = nfs_direct_pgio_init,
294 .completion = nfs_direct_read_completion,
298 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
299 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
300 * bail and stop sending more reads. Read length accounting is
301 * handled automatically by nfs_direct_read_result(). Otherwise, if
302 * no requests have been sent, just return an error.
304 static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
305 const struct iovec *iov,
308 struct nfs_direct_req *dreq = desc->pg_dreq;
309 struct nfs_open_context *ctx = dreq->ctx;
310 struct inode *inode = ctx->dentry->d_inode;
311 unsigned long user_addr = (unsigned long)iov->iov_base;
312 size_t count = iov->iov_len;
313 size_t rsize = NFS_SERVER(inode)->rsize;
317 struct page **pagevec = NULL;
324 pgbase = user_addr & ~PAGE_MASK;
325 bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
328 npages = nfs_page_array_len(pgbase, bytes);
330 pagevec = kmalloc(npages * sizeof(struct page *),
334 down_read(¤t->mm->mmap_sem);
335 result = get_user_pages(current, current->mm, user_addr,
336 npages, 1, 0, pagevec, NULL);
337 up_read(¤t->mm->mmap_sem);
340 if ((unsigned)result < npages) {
341 bytes = result * PAGE_SIZE;
342 if (bytes <= pgbase) {
343 nfs_direct_release_pages(pagevec, result);
350 for (i = 0; i < npages; i++) {
351 struct nfs_page *req;
352 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
353 /* XXX do we need to do the eof zeroing found in async_filler? */
354 req = nfs_create_request(dreq->ctx, dreq->inode,
358 result = PTR_ERR(req);
361 req->wb_index = pos >> PAGE_SHIFT;
362 req->wb_offset = pos & ~PAGE_MASK;
363 if (!nfs_pageio_add_request(desc, req)) {
364 result = desc->pg_error;
365 nfs_release_request(req);
371 user_addr += req_len;
375 /* The nfs_page now hold references to these pages */
376 nfs_direct_release_pages(pagevec, npages);
377 } while (count != 0 && result >= 0);
383 return result < 0 ? (ssize_t) result : -EFAULT;
386 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
387 const struct iovec *iov,
388 unsigned long nr_segs,
391 struct nfs_pageio_descriptor desc;
392 ssize_t result = -EINVAL;
393 size_t requested_bytes = 0;
396 nfs_pageio_init_read(&desc, dreq->inode,
397 &nfs_direct_read_completion_ops);
401 for (seg = 0; seg < nr_segs; seg++) {
402 const struct iovec *vec = &iov[seg];
403 result = nfs_direct_read_schedule_segment(&desc, vec, pos);
406 requested_bytes += result;
407 if ((size_t)result < vec->iov_len)
412 nfs_pageio_complete(&desc);
415 * If no bytes were started, return the error, and let the
416 * generic layer handle the completion.
418 if (requested_bytes == 0) {
419 nfs_direct_req_release(dreq);
420 return result < 0 ? result : -EIO;
424 nfs_direct_complete(dreq);
428 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
429 unsigned long nr_segs, loff_t pos)
431 ssize_t result = -ENOMEM;
432 struct inode *inode = iocb->ki_filp->f_mapping->host;
433 struct nfs_direct_req *dreq;
435 dreq = nfs_direct_req_alloc();
440 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
441 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
442 if (dreq->l_ctx == NULL)
444 if (!is_sync_kiocb(iocb))
447 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
449 result = nfs_direct_wait(dreq);
451 nfs_direct_req_release(dreq);
456 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
457 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
459 struct nfs_pageio_descriptor desc;
460 struct nfs_page *req, *tmp;
462 struct nfs_commit_info cinfo;
465 nfs_init_cinfo_from_dreq(&cinfo, dreq);
466 pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
467 spin_lock(cinfo.lock);
468 nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
469 spin_unlock(cinfo.lock);
474 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE,
475 &nfs_direct_write_completion_ops);
478 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
479 if (!nfs_pageio_add_request(&desc, req)) {
480 nfs_list_add_request(req, &failed);
481 spin_lock(cinfo.lock);
484 spin_unlock(cinfo.lock);
487 nfs_pageio_complete(&desc);
489 while (!list_empty(&failed))
490 nfs_unlock_and_release_request(req);
493 nfs_direct_write_complete(dreq, dreq->inode);
496 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
498 struct nfs_direct_req *dreq = data->dreq;
499 struct nfs_commit_info cinfo;
500 struct nfs_page *req;
501 int status = data->task.tk_status;
503 nfs_init_cinfo_from_dreq(&cinfo, dreq);
505 dprintk("NFS: %5u commit failed with error %d.\n",
506 data->task.tk_pid, status);
507 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
508 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
509 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
510 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
513 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
514 while (!list_empty(&data->pages)) {
515 req = nfs_list_entry(data->pages.next);
516 nfs_list_remove_request(req);
517 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
518 /* Note the rewrite will go through mds */
519 kref_get(&req->wb_kref);
520 nfs_mark_request_commit(req, NULL, &cinfo);
522 nfs_unlock_and_release_request(req);
525 if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
526 nfs_direct_write_complete(dreq, data->inode);
529 static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
531 /* There is no lock to clear */
534 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
535 .completion = nfs_direct_commit_complete,
536 .error_cleanup = nfs_direct_error_cleanup,
539 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
542 struct nfs_commit_info cinfo;
545 nfs_init_cinfo_from_dreq(&cinfo, dreq);
546 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
547 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
548 if (res < 0) /* res == -ENOMEM */
549 nfs_direct_write_reschedule(dreq);
552 static void nfs_direct_write_schedule_work(struct work_struct *work)
554 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
555 int flags = dreq->flags;
559 case NFS_ODIRECT_DO_COMMIT:
560 nfs_direct_commit_schedule(dreq);
562 case NFS_ODIRECT_RESCHED_WRITES:
563 nfs_direct_write_reschedule(dreq);
566 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
567 nfs_direct_complete(dreq);
571 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
573 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
577 static void nfs_direct_write_schedule_work(struct work_struct *work)
581 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
583 nfs_zap_mapping(inode, inode->i_mapping);
584 nfs_direct_complete(dreq);
589 * NB: Return the value of the first error return code. Subsequent
590 * errors after the first one are ignored.
593 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
594 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
595 * bail and stop sending more writes. Write length accounting is
596 * handled automatically by nfs_direct_write_result(). Otherwise, if
597 * no requests have been sent, just return an error.
599 static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
600 const struct iovec *iov,
603 struct nfs_direct_req *dreq = desc->pg_dreq;
604 struct nfs_open_context *ctx = dreq->ctx;
605 struct inode *inode = ctx->dentry->d_inode;
606 unsigned long user_addr = (unsigned long)iov->iov_base;
607 size_t count = iov->iov_len;
608 size_t wsize = NFS_SERVER(inode)->wsize;
612 struct page **pagevec = NULL;
619 pgbase = user_addr & ~PAGE_MASK;
620 bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
623 npages = nfs_page_array_len(pgbase, bytes);
625 pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
629 down_read(¤t->mm->mmap_sem);
630 result = get_user_pages(current, current->mm, user_addr,
631 npages, 0, 0, pagevec, NULL);
632 up_read(¤t->mm->mmap_sem);
636 if ((unsigned)result < npages) {
637 bytes = result * PAGE_SIZE;
638 if (bytes <= pgbase) {
639 nfs_direct_release_pages(pagevec, result);
646 for (i = 0; i < npages; i++) {
647 struct nfs_page *req;
648 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
650 req = nfs_create_request(dreq->ctx, dreq->inode,
654 result = PTR_ERR(req);
657 nfs_lock_request(req);
658 req->wb_index = pos >> PAGE_SHIFT;
659 req->wb_offset = pos & ~PAGE_MASK;
660 if (!nfs_pageio_add_request(desc, req)) {
661 result = desc->pg_error;
662 nfs_unlock_and_release_request(req);
668 user_addr += req_len;
672 /* The nfs_page now hold references to these pages */
673 nfs_direct_release_pages(pagevec, npages);
674 } while (count != 0 && result >= 0);
680 return result < 0 ? (ssize_t) result : -EFAULT;
683 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
685 struct nfs_direct_req *dreq = hdr->dreq;
686 struct nfs_commit_info cinfo;
688 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
690 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
693 nfs_init_cinfo_from_dreq(&cinfo, dreq);
695 spin_lock(&dreq->lock);
697 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
699 dreq->error = hdr->error;
701 if (dreq->error != 0)
702 bit = NFS_IOHDR_ERROR;
704 dreq->count += hdr->good_bytes;
705 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
706 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
707 bit = NFS_IOHDR_NEED_RESCHED;
708 } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
709 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
710 bit = NFS_IOHDR_NEED_RESCHED;
711 else if (dreq->flags == 0) {
712 memcpy(&dreq->verf, &req->wb_verf,
714 bit = NFS_IOHDR_NEED_COMMIT;
715 dreq->flags = NFS_ODIRECT_DO_COMMIT;
716 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
717 if (memcmp(&dreq->verf, &req->wb_verf, sizeof(dreq->verf))) {
718 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
719 bit = NFS_IOHDR_NEED_RESCHED;
721 bit = NFS_IOHDR_NEED_COMMIT;
725 spin_unlock(&dreq->lock);
727 while (!list_empty(&hdr->pages)) {
728 req = nfs_list_entry(hdr->pages.next);
729 nfs_list_remove_request(req);
731 case NFS_IOHDR_NEED_RESCHED:
732 case NFS_IOHDR_NEED_COMMIT:
733 kref_get(&req->wb_kref);
734 nfs_mark_request_commit(req, hdr->lseg, &cinfo);
736 nfs_unlock_and_release_request(req);
741 nfs_direct_write_complete(dreq, hdr->inode);
745 static void nfs_write_sync_pgio_error(struct list_head *head)
747 struct nfs_page *req;
749 while (!list_empty(head)) {
750 req = nfs_list_entry(head->next);
751 nfs_list_remove_request(req);
752 nfs_unlock_and_release_request(req);
756 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
757 .error_cleanup = nfs_write_sync_pgio_error,
758 .init_hdr = nfs_direct_pgio_init,
759 .completion = nfs_direct_write_completion,
762 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
763 const struct iovec *iov,
764 unsigned long nr_segs,
767 struct nfs_pageio_descriptor desc;
769 size_t requested_bytes = 0;
772 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_COND_STABLE,
773 &nfs_direct_write_completion_ops);
777 for (seg = 0; seg < nr_segs; seg++) {
778 const struct iovec *vec = &iov[seg];
779 result = nfs_direct_write_schedule_segment(&desc, vec, pos);
782 requested_bytes += result;
783 if ((size_t)result < vec->iov_len)
787 nfs_pageio_complete(&desc);
790 * If no bytes were started, return the error, and let the
791 * generic layer handle the completion.
793 if (requested_bytes == 0) {
794 nfs_direct_req_release(dreq);
795 return result < 0 ? result : -EIO;
799 nfs_direct_write_complete(dreq, dreq->inode);
803 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
804 unsigned long nr_segs, loff_t pos,
807 ssize_t result = -ENOMEM;
808 struct inode *inode = iocb->ki_filp->f_mapping->host;
809 struct nfs_direct_req *dreq;
811 dreq = nfs_direct_req_alloc();
816 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
817 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
818 if (dreq->l_ctx == NULL)
820 if (!is_sync_kiocb(iocb))
823 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos);
825 result = nfs_direct_wait(dreq);
827 nfs_direct_req_release(dreq);
833 * nfs_file_direct_read - file direct read operation for NFS files
834 * @iocb: target I/O control block
835 * @iov: vector of user buffers into which to read data
836 * @nr_segs: size of iov vector
837 * @pos: byte offset in file where reading starts
839 * We use this function for direct reads instead of calling
840 * generic_file_aio_read() in order to avoid gfar's check to see if
841 * the request starts before the end of the file. For that check
842 * to work, we must generate a GETATTR before each direct read, and
843 * even then there is a window between the GETATTR and the subsequent
844 * READ where the file size could change. Our preference is simply
845 * to do all reads the application wants, and the server will take
846 * care of managing the end of file boundary.
848 * This function also eliminates unnecessarily updating the file's
849 * atime locally, as the NFS server sets the file's atime, and this
850 * client must read the updated atime from the server back into its
853 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
854 unsigned long nr_segs, loff_t pos)
856 ssize_t retval = -EINVAL;
857 struct file *file = iocb->ki_filp;
858 struct address_space *mapping = file->f_mapping;
861 count = iov_length(iov, nr_segs);
862 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
864 dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
865 file->f_path.dentry->d_parent->d_name.name,
866 file->f_path.dentry->d_name.name,
867 count, (long long) pos);
873 retval = nfs_sync_mapping(mapping);
877 task_io_account_read(count);
879 retval = nfs_direct_read(iocb, iov, nr_segs, pos);
881 iocb->ki_pos = pos + retval;
888 * nfs_file_direct_write - file direct write operation for NFS files
889 * @iocb: target I/O control block
890 * @iov: vector of user buffers from which to write data
891 * @nr_segs: size of iov vector
892 * @pos: byte offset in file where writing starts
894 * We use this function for direct writes instead of calling
895 * generic_file_aio_write() in order to avoid taking the inode
896 * semaphore and updating the i_size. The NFS server will set
897 * the new i_size and this client must read the updated size
898 * back into its cache. We let the server do generic write
899 * parameter checking and report problems.
901 * We eliminate local atime updates, see direct read above.
903 * We avoid unnecessary page cache invalidations for normal cached
904 * readers of this file.
906 * Note that O_APPEND is not supported for NFS direct writes, as there
907 * is no atomic O_APPEND write facility in the NFS protocol.
909 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
910 unsigned long nr_segs, loff_t pos)
912 ssize_t retval = -EINVAL;
913 struct file *file = iocb->ki_filp;
914 struct address_space *mapping = file->f_mapping;
917 count = iov_length(iov, nr_segs);
918 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
920 dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
921 file->f_path.dentry->d_parent->d_name.name,
922 file->f_path.dentry->d_name.name,
923 count, (long long) pos);
925 retval = generic_write_checks(file, &pos, &count, 0);
930 if ((ssize_t) count < 0)
936 retval = nfs_sync_mapping(mapping);
940 task_io_account_write(count);
942 retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
944 struct inode *inode = mapping->host;
946 iocb->ki_pos = pos + retval;
947 spin_lock(&inode->i_lock);
948 if (i_size_read(inode) < iocb->ki_pos)
949 i_size_write(inode, iocb->ki_pos);
950 spin_unlock(&inode->i_lock);
957 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
960 int __init nfs_init_directcache(void)
962 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
963 sizeof(struct nfs_direct_req),
964 0, (SLAB_RECLAIM_ACCOUNT|
967 if (nfs_direct_cachep == NULL)
974 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
977 void nfs_destroy_directcache(void)
979 kmem_cache_destroy(nfs_direct_cachep);