NFS: Too many GETATTR and ACCESS calls after direct I/O
[linux-2.6.git] / fs / nfs / direct.c
1 /*
2  * linux/fs/nfs/direct.c
3  *
4  * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
5  *
6  * High-performance uncached I/O for the Linux NFS client
7  *
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.
16  *
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.
23  *
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.
28  *
29  * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
30  * help from Andrew Morton.
31  *
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
38  *
39  */
40
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
48 #include <linux/nfs_fs.h>
49 #include <linux/nfs_page.h>
50 #include <linux/sunrpc/clnt.h>
51
52 #include <asm/system.h>
53 #include <asm/uaccess.h>
54 #include <asm/atomic.h>
55
56 #include "internal.h"
57 #include "iostat.h"
58
59 #define NFSDBG_FACILITY         NFSDBG_VFS
60
61 static struct kmem_cache *nfs_direct_cachep;
62
63 /*
64  * This represents a set of asynchronous requests that we're waiting on
65  */
66 struct nfs_direct_req {
67         struct kref             kref;           /* release manager */
68
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 */
73
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 */
80
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 */
88 };
89
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;
92
93 static inline void get_dreq(struct nfs_direct_req *dreq)
94 {
95         atomic_inc(&dreq->io_count);
96 }
97
98 static inline int put_dreq(struct nfs_direct_req *dreq)
99 {
100         return atomic_dec_and_test(&dreq->io_count);
101 }
102
103 /**
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
110  *
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.
115  */
116 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
117 {
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);
121
122         return -EINVAL;
123 }
124
125 static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
126 {
127         unsigned int npages;
128         unsigned int i;
129
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);
138         }
139 }
140
141 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
142 {
143         unsigned int i;
144         for (i = 0; i < npages; i++)
145                 page_cache_release(pages[i]);
146 }
147
148 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
149 {
150         struct nfs_direct_req *dreq;
151
152         dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
153         if (!dreq)
154                 return NULL;
155
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;
167
168         return dreq;
169 }
170
171 static void nfs_direct_req_free(struct kref *kref)
172 {
173         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
174
175         if (dreq->ctx != NULL)
176                 put_nfs_open_context(dreq->ctx);
177         kmem_cache_free(nfs_direct_cachep, dreq);
178 }
179
180 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
181 {
182         kref_put(&dreq->kref, nfs_direct_req_free);
183 }
184
185 /*
186  * Collects and returns the final error value/byte-count.
187  */
188 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
189 {
190         ssize_t result = -EIOCBQUEUED;
191
192         /* Async requests don't wait here */
193         if (dreq->iocb)
194                 goto out;
195
196         result = wait_for_completion_killable(&dreq->completion);
197
198         if (!result)
199                 result = dreq->error;
200         if (!result)
201                 result = dreq->count;
202
203 out:
204         return (ssize_t) result;
205 }
206
207 /*
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.
210  */
211 static void nfs_direct_complete(struct nfs_direct_req *dreq)
212 {
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);
218         }
219         complete_all(&dreq->completion);
220
221         nfs_direct_req_release(dreq);
222 }
223
224 /*
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).
228  */
229 static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
230 {
231         struct nfs_read_data *data = calldata;
232
233         nfs_readpage_result(task, data);
234 }
235
236 static void nfs_direct_read_release(void *calldata)
237 {
238
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;
242
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);
253         }
254         nfs_direct_release_pages(data->pagevec, data->npages);
255
256         if (put_dreq(dreq))
257                 nfs_direct_complete(dreq);
258         nfs_readdata_free(data);
259 }
260
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,
267 };
268
269 /*
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.
275  */
276 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
277                                                 const struct iovec *iov,
278                                                 loff_t pos)
279 {
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,
288         };
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,
295         };
296         unsigned int pgbase;
297         int result;
298         ssize_t started = 0;
299
300         do {
301                 struct nfs_read_data *data;
302                 size_t bytes;
303
304                 pgbase = user_addr & ~PAGE_MASK;
305                 bytes = min(rsize,count);
306
307                 result = -ENOMEM;
308                 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
309                 if (unlikely(!data))
310                         break;
311
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;
319                 }
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;
326                         }
327                         bytes -= pgbase;
328                         data->npages = result;
329                 }
330
331                 get_dreq(dreq);
332
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                 nfs_fattr_init(&data->fattr);
346                 msg.rpc_argp = &data->args;
347                 msg.rpc_resp = &data->res;
348
349                 task_setup_data.task = &data->task;
350                 task_setup_data.callback_data = data;
351                 NFS_PROTO(inode)->read_setup(data, &msg);
352
353                 task = rpc_run_task(&task_setup_data);
354                 if (IS_ERR(task))
355                         break;
356                 rpc_put_task(task);
357
358                 dprintk("NFS: %5u initiated direct read call "
359                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
360                                 data->task.tk_pid,
361                                 inode->i_sb->s_id,
362                                 (long long)NFS_FILEID(inode),
363                                 bytes,
364                                 (unsigned long long)data->args.offset);
365
366                 started += bytes;
367                 user_addr += bytes;
368                 pos += bytes;
369                 /* FIXME: Remove this unnecessary math from final patch */
370                 pgbase += bytes;
371                 pgbase &= ~PAGE_MASK;
372                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
373
374                 count -= bytes;
375         } while (count != 0);
376
377         if (started)
378                 return started;
379         return result < 0 ? (ssize_t) result : -EFAULT;
380 }
381
382 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
383                                               const struct iovec *iov,
384                                               unsigned long nr_segs,
385                                               loff_t pos)
386 {
387         ssize_t result = -EINVAL;
388         size_t requested_bytes = 0;
389         unsigned long seg;
390
391         get_dreq(dreq);
392
393         for (seg = 0; seg < nr_segs; seg++) {
394                 const struct iovec *vec = &iov[seg];
395                 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
396                 if (result < 0)
397                         break;
398                 requested_bytes += result;
399                 if ((size_t)result < vec->iov_len)
400                         break;
401                 pos += vec->iov_len;
402         }
403
404         if (put_dreq(dreq))
405                 nfs_direct_complete(dreq);
406
407         if (requested_bytes != 0)
408                 return 0;
409
410         if (result < 0)
411                 return result;
412         return -EIO;
413 }
414
415 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
416                                unsigned long nr_segs, loff_t pos)
417 {
418         ssize_t result = 0;
419         struct inode *inode = iocb->ki_filp->f_mapping->host;
420         struct nfs_direct_req *dreq;
421
422         dreq = nfs_direct_req_alloc();
423         if (!dreq)
424                 return -ENOMEM;
425
426         dreq->inode = inode;
427         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
428         if (!is_sync_kiocb(iocb))
429                 dreq->iocb = iocb;
430
431         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
432         if (!result)
433                 result = nfs_direct_wait(dreq);
434         nfs_direct_req_release(dreq);
435
436         return result;
437 }
438
439 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
440 {
441         while (!list_empty(&dreq->rewrite_list)) {
442                 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
443                 list_del(&data->pages);
444                 nfs_direct_release_pages(data->pagevec, data->npages);
445                 nfs_writedata_free(data);
446         }
447 }
448
449 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
450 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
451 {
452         struct inode *inode = dreq->inode;
453         struct list_head *p;
454         struct nfs_write_data *data;
455         struct rpc_task *task;
456         struct rpc_message msg = {
457                 .rpc_cred = dreq->ctx->cred,
458         };
459         struct rpc_task_setup task_setup_data = {
460                 .rpc_client = NFS_CLIENT(inode),
461                 .rpc_message = &msg,
462                 .callback_ops = &nfs_write_direct_ops,
463                 .workqueue = nfsiod_workqueue,
464                 .flags = RPC_TASK_ASYNC,
465         };
466
467         dreq->count = 0;
468         get_dreq(dreq);
469
470         list_for_each(p, &dreq->rewrite_list) {
471                 data = list_entry(p, struct nfs_write_data, pages);
472
473                 get_dreq(dreq);
474
475                 /* Use stable writes */
476                 data->args.stable = NFS_FILE_SYNC;
477
478                 /*
479                  * Reset data->res.
480                  */
481                 nfs_fattr_init(&data->fattr);
482                 data->res.count = data->args.count;
483                 memset(&data->verf, 0, sizeof(data->verf));
484
485                 /*
486                  * Reuse data->task; data->args should not have changed
487                  * since the original request was sent.
488                  */
489                 task_setup_data.task = &data->task;
490                 task_setup_data.callback_data = data;
491                 msg.rpc_argp = &data->args;
492                 msg.rpc_resp = &data->res;
493                 NFS_PROTO(inode)->write_setup(data, &msg);
494
495                 /*
496                  * We're called via an RPC callback, so BKL is already held.
497                  */
498                 task = rpc_run_task(&task_setup_data);
499                 if (!IS_ERR(task))
500                         rpc_put_task(task);
501
502                 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
503                                 data->task.tk_pid,
504                                 inode->i_sb->s_id,
505                                 (long long)NFS_FILEID(inode),
506                                 data->args.count,
507                                 (unsigned long long)data->args.offset);
508         }
509
510         if (put_dreq(dreq))
511                 nfs_direct_write_complete(dreq, inode);
512 }
513
514 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
515 {
516         struct nfs_write_data *data = calldata;
517
518         /* Call the NFS version-specific code */
519         NFS_PROTO(data->inode)->commit_done(task, data);
520 }
521
522 static void nfs_direct_commit_release(void *calldata)
523 {
524         struct nfs_write_data *data = calldata;
525         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
526         int status = data->task.tk_status;
527
528         if (status < 0) {
529                 dprintk("NFS: %5u commit failed with error %d.\n",
530                                 data->task.tk_pid, status);
531                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
532         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
533                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
534                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
535         }
536
537         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
538         nfs_direct_write_complete(dreq, data->inode);
539         nfs_commit_free(data);
540 }
541
542 static const struct rpc_call_ops nfs_commit_direct_ops = {
543 #if defined(CONFIG_NFS_V4_1)
544         .rpc_call_prepare = nfs_write_prepare,
545 #endif /* CONFIG_NFS_V4_1 */
546         .rpc_call_done = nfs_direct_commit_result,
547         .rpc_release = nfs_direct_commit_release,
548 };
549
550 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
551 {
552         struct nfs_write_data *data = dreq->commit_data;
553         struct rpc_task *task;
554         struct rpc_message msg = {
555                 .rpc_argp = &data->args,
556                 .rpc_resp = &data->res,
557                 .rpc_cred = dreq->ctx->cred,
558         };
559         struct rpc_task_setup task_setup_data = {
560                 .task = &data->task,
561                 .rpc_client = NFS_CLIENT(dreq->inode),
562                 .rpc_message = &msg,
563                 .callback_ops = &nfs_commit_direct_ops,
564                 .callback_data = data,
565                 .workqueue = nfsiod_workqueue,
566                 .flags = RPC_TASK_ASYNC,
567         };
568
569         data->inode = dreq->inode;
570         data->cred = msg.rpc_cred;
571
572         data->args.fh = NFS_FH(data->inode);
573         data->args.offset = 0;
574         data->args.count = 0;
575         data->args.context = dreq->ctx;
576         data->res.count = 0;
577         data->res.fattr = &data->fattr;
578         data->res.verf = &data->verf;
579         nfs_fattr_init(&data->fattr);
580
581         NFS_PROTO(data->inode)->commit_setup(data, &msg);
582
583         /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
584         dreq->commit_data = NULL;
585
586         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
587
588         task = rpc_run_task(&task_setup_data);
589         if (!IS_ERR(task))
590                 rpc_put_task(task);
591 }
592
593 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
594 {
595         int flags = dreq->flags;
596
597         dreq->flags = 0;
598         switch (flags) {
599                 case NFS_ODIRECT_DO_COMMIT:
600                         nfs_direct_commit_schedule(dreq);
601                         break;
602                 case NFS_ODIRECT_RESCHED_WRITES:
603                         nfs_direct_write_reschedule(dreq);
604                         break;
605                 default:
606                         if (dreq->commit_data != NULL)
607                                 nfs_commit_free(dreq->commit_data);
608                         nfs_direct_free_writedata(dreq);
609                         nfs_zap_mapping(inode, inode->i_mapping);
610                         nfs_direct_complete(dreq);
611         }
612 }
613
614 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
615 {
616         dreq->commit_data = nfs_commitdata_alloc();
617         if (dreq->commit_data != NULL)
618                 dreq->commit_data->req = (struct nfs_page *) dreq;
619 }
620 #else
621 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
622 {
623         dreq->commit_data = NULL;
624 }
625
626 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
627 {
628         nfs_direct_free_writedata(dreq);
629         nfs_zap_mapping(inode, inode->i_mapping);
630         nfs_direct_complete(dreq);
631 }
632 #endif
633
634 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
635 {
636         struct nfs_write_data *data = calldata;
637
638         if (nfs_writeback_done(task, data) != 0)
639                 return;
640 }
641
642 /*
643  * NB: Return the value of the first error return code.  Subsequent
644  *     errors after the first one are ignored.
645  */
646 static void nfs_direct_write_release(void *calldata)
647 {
648         struct nfs_write_data *data = calldata;
649         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
650         int status = data->task.tk_status;
651
652         spin_lock(&dreq->lock);
653
654         if (unlikely(status < 0)) {
655                 /* An error has occurred, so we should not commit */
656                 dreq->flags = 0;
657                 dreq->error = status;
658         }
659         if (unlikely(dreq->error != 0))
660                 goto out_unlock;
661
662         dreq->count += data->res.count;
663
664         if (data->res.verf->committed != NFS_FILE_SYNC) {
665                 switch (dreq->flags) {
666                         case 0:
667                                 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
668                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
669                                 break;
670                         case NFS_ODIRECT_DO_COMMIT:
671                                 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
672                                         dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
673                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
674                                 }
675                 }
676         }
677 out_unlock:
678         spin_unlock(&dreq->lock);
679
680         if (put_dreq(dreq))
681                 nfs_direct_write_complete(dreq, data->inode);
682 }
683
684 static const struct rpc_call_ops nfs_write_direct_ops = {
685 #if defined(CONFIG_NFS_V4_1)
686         .rpc_call_prepare = nfs_write_prepare,
687 #endif /* CONFIG_NFS_V4_1 */
688         .rpc_call_done = nfs_direct_write_result,
689         .rpc_release = nfs_direct_write_release,
690 };
691
692 /*
693  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
694  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
695  * bail and stop sending more writes.  Write length accounting is
696  * handled automatically by nfs_direct_write_result().  Otherwise, if
697  * no requests have been sent, just return an error.
698  */
699 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
700                                                  const struct iovec *iov,
701                                                  loff_t pos, int sync)
702 {
703         struct nfs_open_context *ctx = dreq->ctx;
704         struct inode *inode = ctx->path.dentry->d_inode;
705         unsigned long user_addr = (unsigned long)iov->iov_base;
706         size_t count = iov->iov_len;
707         struct rpc_task *task;
708         struct rpc_message msg = {
709                 .rpc_cred = ctx->cred,
710         };
711         struct rpc_task_setup task_setup_data = {
712                 .rpc_client = NFS_CLIENT(inode),
713                 .rpc_message = &msg,
714                 .callback_ops = &nfs_write_direct_ops,
715                 .workqueue = nfsiod_workqueue,
716                 .flags = RPC_TASK_ASYNC,
717         };
718         size_t wsize = NFS_SERVER(inode)->wsize;
719         unsigned int pgbase;
720         int result;
721         ssize_t started = 0;
722
723         do {
724                 struct nfs_write_data *data;
725                 size_t bytes;
726
727                 pgbase = user_addr & ~PAGE_MASK;
728                 bytes = min(wsize,count);
729
730                 result = -ENOMEM;
731                 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
732                 if (unlikely(!data))
733                         break;
734
735                 down_read(&current->mm->mmap_sem);
736                 result = get_user_pages(current, current->mm, user_addr,
737                                         data->npages, 0, 0, data->pagevec, NULL);
738                 up_read(&current->mm->mmap_sem);
739                 if (result < 0) {
740                         nfs_writedata_free(data);
741                         break;
742                 }
743                 if ((unsigned)result < data->npages) {
744                         bytes = result * PAGE_SIZE;
745                         if (bytes <= pgbase) {
746                                 nfs_direct_release_pages(data->pagevec, result);
747                                 nfs_writedata_free(data);
748                                 break;
749                         }
750                         bytes -= pgbase;
751                         data->npages = result;
752                 }
753
754                 get_dreq(dreq);
755
756                 list_move_tail(&data->pages, &dreq->rewrite_list);
757
758                 data->req = (struct nfs_page *) dreq;
759                 data->inode = inode;
760                 data->cred = msg.rpc_cred;
761                 data->args.fh = NFS_FH(inode);
762                 data->args.context = ctx;
763                 data->args.offset = pos;
764                 data->args.pgbase = pgbase;
765                 data->args.pages = data->pagevec;
766                 data->args.count = bytes;
767                 data->args.stable = sync;
768                 data->res.fattr = &data->fattr;
769                 data->res.count = bytes;
770                 data->res.verf = &data->verf;
771                 nfs_fattr_init(&data->fattr);
772
773                 task_setup_data.task = &data->task;
774                 task_setup_data.callback_data = data;
775                 msg.rpc_argp = &data->args;
776                 msg.rpc_resp = &data->res;
777                 NFS_PROTO(inode)->write_setup(data, &msg);
778
779                 task = rpc_run_task(&task_setup_data);
780                 if (IS_ERR(task))
781                         break;
782                 rpc_put_task(task);
783
784                 dprintk("NFS: %5u initiated direct write call "
785                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
786                                 data->task.tk_pid,
787                                 inode->i_sb->s_id,
788                                 (long long)NFS_FILEID(inode),
789                                 bytes,
790                                 (unsigned long long)data->args.offset);
791
792                 started += bytes;
793                 user_addr += bytes;
794                 pos += bytes;
795
796                 /* FIXME: Remove this useless math from the final patch */
797                 pgbase += bytes;
798                 pgbase &= ~PAGE_MASK;
799                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
800
801                 count -= bytes;
802         } while (count != 0);
803
804         if (started)
805                 return started;
806         return result < 0 ? (ssize_t) result : -EFAULT;
807 }
808
809 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
810                                                const struct iovec *iov,
811                                                unsigned long nr_segs,
812                                                loff_t pos, int sync)
813 {
814         ssize_t result = 0;
815         size_t requested_bytes = 0;
816         unsigned long seg;
817
818         get_dreq(dreq);
819
820         for (seg = 0; seg < nr_segs; seg++) {
821                 const struct iovec *vec = &iov[seg];
822                 result = nfs_direct_write_schedule_segment(dreq, vec,
823                                                            pos, sync);
824                 if (result < 0)
825                         break;
826                 requested_bytes += result;
827                 if ((size_t)result < vec->iov_len)
828                         break;
829                 pos += vec->iov_len;
830         }
831
832         if (put_dreq(dreq))
833                 nfs_direct_write_complete(dreq, dreq->inode);
834
835         if (requested_bytes != 0)
836                 return 0;
837
838         if (result < 0)
839                 return result;
840         return -EIO;
841 }
842
843 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
844                                 unsigned long nr_segs, loff_t pos,
845                                 size_t count)
846 {
847         ssize_t result = 0;
848         struct inode *inode = iocb->ki_filp->f_mapping->host;
849         struct nfs_direct_req *dreq;
850         size_t wsize = NFS_SERVER(inode)->wsize;
851         int sync = NFS_UNSTABLE;
852
853         dreq = nfs_direct_req_alloc();
854         if (!dreq)
855                 return -ENOMEM;
856         nfs_alloc_commit_data(dreq);
857
858         if (dreq->commit_data == NULL || count < wsize)
859                 sync = NFS_FILE_SYNC;
860
861         dreq->inode = inode;
862         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
863         if (!is_sync_kiocb(iocb))
864                 dreq->iocb = iocb;
865
866         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
867         if (!result)
868                 result = nfs_direct_wait(dreq);
869         nfs_direct_req_release(dreq);
870
871         return result;
872 }
873
874 /**
875  * nfs_file_direct_read - file direct read operation for NFS files
876  * @iocb: target I/O control block
877  * @iov: vector of user buffers into which to read data
878  * @nr_segs: size of iov vector
879  * @pos: byte offset in file where reading starts
880  *
881  * We use this function for direct reads instead of calling
882  * generic_file_aio_read() in order to avoid gfar's check to see if
883  * the request starts before the end of the file.  For that check
884  * to work, we must generate a GETATTR before each direct read, and
885  * even then there is a window between the GETATTR and the subsequent
886  * READ where the file size could change.  Our preference is simply
887  * to do all reads the application wants, and the server will take
888  * care of managing the end of file boundary.
889  *
890  * This function also eliminates unnecessarily updating the file's
891  * atime locally, as the NFS server sets the file's atime, and this
892  * client must read the updated atime from the server back into its
893  * cache.
894  */
895 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
896                                 unsigned long nr_segs, loff_t pos)
897 {
898         ssize_t retval = -EINVAL;
899         struct file *file = iocb->ki_filp;
900         struct address_space *mapping = file->f_mapping;
901         size_t count;
902
903         count = iov_length(iov, nr_segs);
904         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
905
906         dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
907                 file->f_path.dentry->d_parent->d_name.name,
908                 file->f_path.dentry->d_name.name,
909                 count, (long long) pos);
910
911         retval = 0;
912         if (!count)
913                 goto out;
914
915         retval = nfs_sync_mapping(mapping);
916         if (retval)
917                 goto out;
918
919         retval = nfs_direct_read(iocb, iov, nr_segs, pos);
920         if (retval > 0)
921                 iocb->ki_pos = pos + retval;
922
923 out:
924         return retval;
925 }
926
927 /**
928  * nfs_file_direct_write - file direct write operation for NFS files
929  * @iocb: target I/O control block
930  * @iov: vector of user buffers from which to write data
931  * @nr_segs: size of iov vector
932  * @pos: byte offset in file where writing starts
933  *
934  * We use this function for direct writes instead of calling
935  * generic_file_aio_write() in order to avoid taking the inode
936  * semaphore and updating the i_size.  The NFS server will set
937  * the new i_size and this client must read the updated size
938  * back into its cache.  We let the server do generic write
939  * parameter checking and report problems.
940  *
941  * We eliminate local atime updates, see direct read above.
942  *
943  * We avoid unnecessary page cache invalidations for normal cached
944  * readers of this file.
945  *
946  * Note that O_APPEND is not supported for NFS direct writes, as there
947  * is no atomic O_APPEND write facility in the NFS protocol.
948  */
949 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
950                                 unsigned long nr_segs, loff_t pos)
951 {
952         ssize_t retval = -EINVAL;
953         struct file *file = iocb->ki_filp;
954         struct address_space *mapping = file->f_mapping;
955         size_t count;
956
957         count = iov_length(iov, nr_segs);
958         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
959
960         dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
961                 file->f_path.dentry->d_parent->d_name.name,
962                 file->f_path.dentry->d_name.name,
963                 count, (long long) pos);
964
965         retval = generic_write_checks(file, &pos, &count, 0);
966         if (retval)
967                 goto out;
968
969         retval = -EINVAL;
970         if ((ssize_t) count < 0)
971                 goto out;
972         retval = 0;
973         if (!count)
974                 goto out;
975
976         retval = nfs_sync_mapping(mapping);
977         if (retval)
978                 goto out;
979
980         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
981
982         if (retval > 0)
983                 iocb->ki_pos = pos + retval;
984
985 out:
986         return retval;
987 }
988
989 /**
990  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
991  *
992  */
993 int __init nfs_init_directcache(void)
994 {
995         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
996                                                 sizeof(struct nfs_direct_req),
997                                                 0, (SLAB_RECLAIM_ACCOUNT|
998                                                         SLAB_MEM_SPREAD),
999                                                 NULL);
1000         if (nfs_direct_cachep == NULL)
1001                 return -ENOMEM;
1002
1003         return 0;
1004 }
1005
1006 /**
1007  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1008  *
1009  */
1010 void nfs_destroy_directcache(void)
1011 {
1012         kmem_cache_destroy(nfs_direct_cachep);
1013 }