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>
49 #include <linux/module.h>
51 #include <linux/nfs_fs.h>
52 #include <linux/nfs_page.h>
53 #include <linux/sunrpc/clnt.h>
55 #include <asm/uaccess.h>
56 #include <linux/atomic.h>
62 #define NFSDBG_FACILITY NFSDBG_VFS
64 static struct kmem_cache *nfs_direct_cachep;
67 * This represents a set of asynchronous requests that we're waiting on
69 struct nfs_direct_req {
70 struct kref kref; /* release manager */
73 struct nfs_open_context *ctx; /* file open context info */
74 struct nfs_lock_context *l_ctx; /* Lock context info */
75 struct kiocb * iocb; /* controlling i/o request */
76 struct inode * inode; /* target file of i/o */
78 /* completion state */
79 atomic_t io_count; /* i/os we're waiting for */
80 spinlock_t lock; /* protect completion state */
81 ssize_t count, /* bytes actually processed */
82 bytes_left, /* bytes left to be sent */
83 error; /* any reported error */
84 struct completion completion; /* wait for i/o completion */
87 struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
88 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
89 struct work_struct work;
91 #define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
92 #define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
93 struct nfs_writeverf verf; /* unstable write verifier */
96 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
97 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
98 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
99 static void nfs_direct_write_schedule_work(struct work_struct *work);
101 static inline void get_dreq(struct nfs_direct_req *dreq)
103 atomic_inc(&dreq->io_count);
106 static inline int put_dreq(struct nfs_direct_req *dreq)
108 return atomic_dec_and_test(&dreq->io_count);
112 * nfs_direct_IO - NFS address space operation for direct I/O
113 * @rw: direction (read or write)
114 * @iocb: target I/O control block
115 * @iov: array of vectors that define I/O buffer
116 * @pos: offset in file to begin the operation
117 * @nr_segs: size of iovec array
119 * The presence of this routine in the address space ops vector means
120 * the NFS client supports direct I/O. However, for most direct IO, we
121 * shunt off direct read and write requests before the VFS gets them,
122 * so this method is only ever called for swap.
124 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
126 #ifndef CONFIG_NFS_SWAP
127 dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
128 iocb->ki_filp->f_path.dentry->d_name.name,
129 (long long) pos, nr_segs);
133 VM_BUG_ON(iocb->ki_left != PAGE_SIZE);
134 VM_BUG_ON(iocb->ki_nbytes != PAGE_SIZE);
136 if (rw == READ || rw == KERNEL_READ)
137 return nfs_file_direct_read(iocb, iov, nr_segs, pos,
138 rw == READ ? true : false);
139 return nfs_file_direct_write(iocb, iov, nr_segs, pos,
140 rw == WRITE ? true : false);
141 #endif /* CONFIG_NFS_SWAP */
144 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
147 for (i = 0; i < npages; i++)
148 page_cache_release(pages[i]);
151 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
152 struct nfs_direct_req *dreq)
154 cinfo->lock = &dreq->lock;
155 cinfo->mds = &dreq->mds_cinfo;
156 cinfo->ds = &dreq->ds_cinfo;
158 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
161 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
163 struct nfs_direct_req *dreq;
165 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
169 kref_init(&dreq->kref);
170 kref_get(&dreq->kref);
171 init_completion(&dreq->completion);
172 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
173 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
174 spin_lock_init(&dreq->lock);
179 static void nfs_direct_req_free(struct kref *kref)
181 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
183 nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo);
184 if (dreq->l_ctx != NULL)
185 nfs_put_lock_context(dreq->l_ctx);
186 if (dreq->ctx != NULL)
187 put_nfs_open_context(dreq->ctx);
188 kmem_cache_free(nfs_direct_cachep, dreq);
191 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
193 kref_put(&dreq->kref, nfs_direct_req_free);
196 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
198 return dreq->bytes_left;
200 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
203 * Collects and returns the final error value/byte-count.
205 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
207 ssize_t result = -EIOCBQUEUED;
209 /* Async requests don't wait here */
213 result = wait_for_completion_killable(&dreq->completion);
216 result = dreq->error;
218 result = dreq->count;
221 return (ssize_t) result;
225 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
226 * the iocb is still valid here if this is a synchronous request.
228 static void nfs_direct_complete(struct nfs_direct_req *dreq)
231 long res = (long) dreq->error;
233 res = (long) dreq->count;
234 aio_complete(dreq->iocb, res, 0);
236 complete_all(&dreq->completion);
238 nfs_direct_req_release(dreq);
241 static void nfs_direct_readpage_release(struct nfs_page *req)
243 dprintk("NFS: direct read done (%s/%lld %d@%lld)\n",
244 req->wb_context->dentry->d_inode->i_sb->s_id,
245 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
247 (long long)req_offset(req));
248 nfs_release_request(req);
251 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
253 unsigned long bytes = 0;
254 struct nfs_direct_req *dreq = hdr->dreq;
256 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
259 spin_lock(&dreq->lock);
260 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
261 dreq->error = hdr->error;
263 dreq->count += hdr->good_bytes;
264 spin_unlock(&dreq->lock);
266 while (!list_empty(&hdr->pages)) {
267 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
268 struct page *page = req->wb_page;
270 if (!PageCompound(page) && bytes < hdr->good_bytes)
271 set_page_dirty(page);
272 bytes += req->wb_bytes;
273 nfs_list_remove_request(req);
274 nfs_direct_readpage_release(req);
278 nfs_direct_complete(dreq);
282 static void nfs_read_sync_pgio_error(struct list_head *head)
284 struct nfs_page *req;
286 while (!list_empty(head)) {
287 req = nfs_list_entry(head->next);
288 nfs_list_remove_request(req);
289 nfs_release_request(req);
293 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
298 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
299 .error_cleanup = nfs_read_sync_pgio_error,
300 .init_hdr = nfs_direct_pgio_init,
301 .completion = nfs_direct_read_completion,
305 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
306 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
307 * bail and stop sending more reads. Read length accounting is
308 * handled automatically by nfs_direct_read_result(). Otherwise, if
309 * no requests have been sent, just return an error.
311 static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
312 const struct iovec *iov,
313 loff_t pos, bool uio)
315 struct nfs_direct_req *dreq = desc->pg_dreq;
316 struct nfs_open_context *ctx = dreq->ctx;
317 struct inode *inode = ctx->dentry->d_inode;
318 unsigned long user_addr = (unsigned long)iov->iov_base;
319 size_t count = iov->iov_len;
320 size_t rsize = NFS_SERVER(inode)->rsize;
324 struct page **pagevec = NULL;
331 pgbase = user_addr & ~PAGE_MASK;
332 bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
335 npages = nfs_page_array_len(pgbase, bytes);
337 pagevec = kmalloc(npages * sizeof(struct page *),
342 down_read(¤t->mm->mmap_sem);
343 result = get_user_pages(current, current->mm, user_addr,
344 npages, 1, 0, pagevec, NULL);
345 up_read(¤t->mm->mmap_sem);
349 WARN_ON(npages != 1);
350 result = get_kernel_page(user_addr, 1, pagevec);
351 if (WARN_ON(result != 1))
355 if ((unsigned)result < npages) {
356 bytes = result * PAGE_SIZE;
357 if (bytes <= pgbase) {
358 nfs_direct_release_pages(pagevec, result);
365 for (i = 0; i < npages; i++) {
366 struct nfs_page *req;
367 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
368 /* XXX do we need to do the eof zeroing found in async_filler? */
369 req = nfs_create_request(dreq->ctx, dreq->inode,
373 result = PTR_ERR(req);
376 req->wb_index = pos >> PAGE_SHIFT;
377 req->wb_offset = pos & ~PAGE_MASK;
378 if (!nfs_pageio_add_request(desc, req)) {
379 result = desc->pg_error;
380 nfs_release_request(req);
386 user_addr += req_len;
389 dreq->bytes_left -= req_len;
391 /* The nfs_page now hold references to these pages */
392 nfs_direct_release_pages(pagevec, npages);
393 } while (count != 0 && result >= 0);
399 return result < 0 ? (ssize_t) result : -EFAULT;
402 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
403 const struct iovec *iov,
404 unsigned long nr_segs,
405 loff_t pos, bool uio)
407 struct nfs_pageio_descriptor desc;
408 ssize_t result = -EINVAL;
409 size_t requested_bytes = 0;
412 NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
413 &nfs_direct_read_completion_ops);
417 for (seg = 0; seg < nr_segs; seg++) {
418 const struct iovec *vec = &iov[seg];
419 result = nfs_direct_read_schedule_segment(&desc, vec, pos, uio);
422 requested_bytes += result;
423 if ((size_t)result < vec->iov_len)
428 nfs_pageio_complete(&desc);
431 * If no bytes were started, return the error, and let the
432 * generic layer handle the completion.
434 if (requested_bytes == 0) {
435 nfs_direct_req_release(dreq);
436 return result < 0 ? result : -EIO;
440 nfs_direct_complete(dreq);
444 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
445 unsigned long nr_segs, loff_t pos, bool uio)
447 ssize_t result = -ENOMEM;
448 struct inode *inode = iocb->ki_filp->f_mapping->host;
449 struct nfs_direct_req *dreq;
450 struct nfs_lock_context *l_ctx;
452 dreq = nfs_direct_req_alloc();
457 dreq->bytes_left = iov_length(iov, nr_segs);
458 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
459 l_ctx = nfs_get_lock_context(dreq->ctx);
461 result = PTR_ERR(l_ctx);
465 if (!is_sync_kiocb(iocb))
468 NFS_I(inode)->read_io += iov_length(iov, nr_segs);
469 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
471 result = nfs_direct_wait(dreq);
473 nfs_direct_req_release(dreq);
478 static void nfs_inode_dio_write_done(struct inode *inode)
480 nfs_zap_mapping(inode, inode->i_mapping);
481 inode_dio_done(inode);
484 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
485 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
487 struct nfs_pageio_descriptor desc;
488 struct nfs_page *req, *tmp;
490 struct nfs_commit_info cinfo;
493 nfs_init_cinfo_from_dreq(&cinfo, dreq);
494 pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
495 spin_lock(cinfo.lock);
496 nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
497 spin_unlock(cinfo.lock);
502 NFS_PROTO(dreq->inode)->write_pageio_init(&desc, dreq->inode, FLUSH_STABLE,
503 &nfs_direct_write_completion_ops);
506 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
507 if (!nfs_pageio_add_request(&desc, req)) {
508 nfs_list_remove_request(req);
509 nfs_list_add_request(req, &failed);
510 spin_lock(cinfo.lock);
513 spin_unlock(cinfo.lock);
515 nfs_release_request(req);
517 nfs_pageio_complete(&desc);
519 while (!list_empty(&failed)) {
520 req = nfs_list_entry(failed.next);
521 nfs_list_remove_request(req);
522 nfs_unlock_and_release_request(req);
526 nfs_direct_write_complete(dreq, dreq->inode);
529 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
531 struct nfs_direct_req *dreq = data->dreq;
532 struct nfs_commit_info cinfo;
533 struct nfs_page *req;
534 int status = data->task.tk_status;
536 nfs_init_cinfo_from_dreq(&cinfo, dreq);
538 dprintk("NFS: %5u commit failed with error %d.\n",
539 data->task.tk_pid, status);
540 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
541 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
542 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
543 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
546 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
547 while (!list_empty(&data->pages)) {
548 req = nfs_list_entry(data->pages.next);
549 nfs_list_remove_request(req);
550 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
551 /* Note the rewrite will go through mds */
552 nfs_mark_request_commit(req, NULL, &cinfo);
554 nfs_release_request(req);
555 nfs_unlock_and_release_request(req);
558 if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
559 nfs_direct_write_complete(dreq, data->inode);
562 static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
564 /* There is no lock to clear */
567 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
568 .completion = nfs_direct_commit_complete,
569 .error_cleanup = nfs_direct_error_cleanup,
572 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
575 struct nfs_commit_info cinfo;
578 nfs_init_cinfo_from_dreq(&cinfo, dreq);
579 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
580 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
581 if (res < 0) /* res == -ENOMEM */
582 nfs_direct_write_reschedule(dreq);
585 static void nfs_direct_write_schedule_work(struct work_struct *work)
587 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
588 int flags = dreq->flags;
592 case NFS_ODIRECT_DO_COMMIT:
593 nfs_direct_commit_schedule(dreq);
595 case NFS_ODIRECT_RESCHED_WRITES:
596 nfs_direct_write_reschedule(dreq);
599 nfs_inode_dio_write_done(dreq->inode);
600 nfs_direct_complete(dreq);
604 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
606 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
610 static void nfs_direct_write_schedule_work(struct work_struct *work)
614 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
616 nfs_inode_dio_write_done(inode);
617 nfs_direct_complete(dreq);
622 * NB: Return the value of the first error return code. Subsequent
623 * errors after the first one are ignored.
626 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
627 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
628 * bail and stop sending more writes. Write length accounting is
629 * handled automatically by nfs_direct_write_result(). Otherwise, if
630 * no requests have been sent, just return an error.
632 static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
633 const struct iovec *iov,
634 loff_t pos, bool uio)
636 struct nfs_direct_req *dreq = desc->pg_dreq;
637 struct nfs_open_context *ctx = dreq->ctx;
638 struct inode *inode = ctx->dentry->d_inode;
639 unsigned long user_addr = (unsigned long)iov->iov_base;
640 size_t count = iov->iov_len;
641 size_t wsize = NFS_SERVER(inode)->wsize;
645 struct page **pagevec = NULL;
652 pgbase = user_addr & ~PAGE_MASK;
653 bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
656 npages = nfs_page_array_len(pgbase, bytes);
658 pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
663 down_read(¤t->mm->mmap_sem);
664 result = get_user_pages(current, current->mm, user_addr,
665 npages, 0, 0, pagevec, NULL);
666 up_read(¤t->mm->mmap_sem);
670 WARN_ON(npages != 1);
671 result = get_kernel_page(user_addr, 0, pagevec);
672 if (WARN_ON(result != 1))
676 if ((unsigned)result < npages) {
677 bytes = result * PAGE_SIZE;
678 if (bytes <= pgbase) {
679 nfs_direct_release_pages(pagevec, result);
686 for (i = 0; i < npages; i++) {
687 struct nfs_page *req;
688 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
690 req = nfs_create_request(dreq->ctx, dreq->inode,
694 result = PTR_ERR(req);
697 nfs_lock_request(req);
698 req->wb_index = pos >> PAGE_SHIFT;
699 req->wb_offset = pos & ~PAGE_MASK;
700 if (!nfs_pageio_add_request(desc, req)) {
701 result = desc->pg_error;
702 nfs_unlock_and_release_request(req);
708 user_addr += req_len;
711 dreq->bytes_left -= req_len;
713 /* The nfs_page now hold references to these pages */
714 nfs_direct_release_pages(pagevec, npages);
715 } while (count != 0 && result >= 0);
721 return result < 0 ? (ssize_t) result : -EFAULT;
724 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
726 struct nfs_direct_req *dreq = hdr->dreq;
727 struct nfs_commit_info cinfo;
729 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
731 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
734 nfs_init_cinfo_from_dreq(&cinfo, dreq);
736 spin_lock(&dreq->lock);
738 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
740 dreq->error = hdr->error;
742 if (dreq->error != 0)
743 bit = NFS_IOHDR_ERROR;
745 dreq->count += hdr->good_bytes;
746 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
747 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
748 bit = NFS_IOHDR_NEED_RESCHED;
749 } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
750 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
751 bit = NFS_IOHDR_NEED_RESCHED;
752 else if (dreq->flags == 0) {
753 memcpy(&dreq->verf, hdr->verf,
755 bit = NFS_IOHDR_NEED_COMMIT;
756 dreq->flags = NFS_ODIRECT_DO_COMMIT;
757 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
758 if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
759 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
760 bit = NFS_IOHDR_NEED_RESCHED;
762 bit = NFS_IOHDR_NEED_COMMIT;
766 spin_unlock(&dreq->lock);
768 while (!list_empty(&hdr->pages)) {
769 req = nfs_list_entry(hdr->pages.next);
770 nfs_list_remove_request(req);
772 case NFS_IOHDR_NEED_RESCHED:
773 case NFS_IOHDR_NEED_COMMIT:
774 kref_get(&req->wb_kref);
775 nfs_mark_request_commit(req, hdr->lseg, &cinfo);
777 nfs_unlock_and_release_request(req);
782 nfs_direct_write_complete(dreq, hdr->inode);
786 static void nfs_write_sync_pgio_error(struct list_head *head)
788 struct nfs_page *req;
790 while (!list_empty(head)) {
791 req = nfs_list_entry(head->next);
792 nfs_list_remove_request(req);
793 nfs_unlock_and_release_request(req);
797 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
798 .error_cleanup = nfs_write_sync_pgio_error,
799 .init_hdr = nfs_direct_pgio_init,
800 .completion = nfs_direct_write_completion,
803 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
804 const struct iovec *iov,
805 unsigned long nr_segs,
806 loff_t pos, bool uio)
808 struct nfs_pageio_descriptor desc;
809 struct inode *inode = dreq->inode;
811 size_t requested_bytes = 0;
814 NFS_PROTO(inode)->write_pageio_init(&desc, inode, FLUSH_COND_STABLE,
815 &nfs_direct_write_completion_ops);
818 atomic_inc(&inode->i_dio_count);
820 NFS_I(dreq->inode)->write_io += iov_length(iov, nr_segs);
821 for (seg = 0; seg < nr_segs; seg++) {
822 const struct iovec *vec = &iov[seg];
823 result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
826 requested_bytes += result;
827 if ((size_t)result < vec->iov_len)
831 nfs_pageio_complete(&desc);
834 * If no bytes were started, return the error, and let the
835 * generic layer handle the completion.
837 if (requested_bytes == 0) {
838 inode_dio_done(inode);
839 nfs_direct_req_release(dreq);
840 return result < 0 ? result : -EIO;
844 nfs_direct_write_complete(dreq, dreq->inode);
848 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
849 unsigned long nr_segs, loff_t pos,
850 size_t count, bool uio)
852 ssize_t result = -ENOMEM;
853 struct inode *inode = iocb->ki_filp->f_mapping->host;
854 struct nfs_direct_req *dreq;
855 struct nfs_lock_context *l_ctx;
857 dreq = nfs_direct_req_alloc();
862 dreq->bytes_left = count;
863 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
864 l_ctx = nfs_get_lock_context(dreq->ctx);
866 result = PTR_ERR(l_ctx);
870 if (!is_sync_kiocb(iocb))
873 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, uio);
875 result = nfs_direct_wait(dreq);
877 nfs_direct_req_release(dreq);
883 * nfs_file_direct_read - file direct read operation for NFS files
884 * @iocb: target I/O control block
885 * @iov: vector of user buffers into which to read data
886 * @nr_segs: size of iov vector
887 * @pos: byte offset in file where reading starts
889 * We use this function for direct reads instead of calling
890 * generic_file_aio_read() in order to avoid gfar's check to see if
891 * the request starts before the end of the file. For that check
892 * to work, we must generate a GETATTR before each direct read, and
893 * even then there is a window between the GETATTR and the subsequent
894 * READ where the file size could change. Our preference is simply
895 * to do all reads the application wants, and the server will take
896 * care of managing the end of file boundary.
898 * This function also eliminates unnecessarily updating the file's
899 * atime locally, as the NFS server sets the file's atime, and this
900 * client must read the updated atime from the server back into its
903 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
904 unsigned long nr_segs, loff_t pos, bool uio)
906 ssize_t retval = -EINVAL;
907 struct file *file = iocb->ki_filp;
908 struct address_space *mapping = file->f_mapping;
911 count = iov_length(iov, nr_segs);
912 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
914 dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
915 file->f_path.dentry->d_parent->d_name.name,
916 file->f_path.dentry->d_name.name,
917 count, (long long) pos);
923 retval = nfs_sync_mapping(mapping);
927 task_io_account_read(count);
929 retval = nfs_direct_read(iocb, iov, nr_segs, pos, uio);
931 iocb->ki_pos = pos + retval;
938 * nfs_file_direct_write - file direct write operation for NFS files
939 * @iocb: target I/O control block
940 * @iov: vector of user buffers from which to write data
941 * @nr_segs: size of iov vector
942 * @pos: byte offset in file where writing starts
944 * We use this function for direct writes instead of calling
945 * generic_file_aio_write() in order to avoid taking the inode
946 * semaphore and updating the i_size. The NFS server will set
947 * the new i_size and this client must read the updated size
948 * back into its cache. We let the server do generic write
949 * parameter checking and report problems.
951 * We eliminate local atime updates, see direct read above.
953 * We avoid unnecessary page cache invalidations for normal cached
954 * readers of this file.
956 * Note that O_APPEND is not supported for NFS direct writes, as there
957 * is no atomic O_APPEND write facility in the NFS protocol.
959 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
960 unsigned long nr_segs, loff_t pos, bool uio)
962 ssize_t retval = -EINVAL;
963 struct file *file = iocb->ki_filp;
964 struct address_space *mapping = file->f_mapping;
967 count = iov_length(iov, nr_segs);
968 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
970 dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
971 file->f_path.dentry->d_parent->d_name.name,
972 file->f_path.dentry->d_name.name,
973 count, (long long) pos);
975 retval = generic_write_checks(file, &pos, &count, 0);
980 if ((ssize_t) count < 0)
986 retval = nfs_sync_mapping(mapping);
990 task_io_account_write(count);
992 retval = nfs_direct_write(iocb, iov, nr_segs, pos, count, uio);
994 struct inode *inode = mapping->host;
996 iocb->ki_pos = pos + retval;
997 spin_lock(&inode->i_lock);
998 if (i_size_read(inode) < iocb->ki_pos)
999 i_size_write(inode, iocb->ki_pos);
1000 spin_unlock(&inode->i_lock);
1007 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1010 int __init nfs_init_directcache(void)
1012 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1013 sizeof(struct nfs_direct_req),
1014 0, (SLAB_RECLAIM_ACCOUNT|
1017 if (nfs_direct_cachep == NULL)
1024 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1027 void nfs_destroy_directcache(void)
1029 kmem_cache_destroy(nfs_direct_cachep);