Merge tag 'split-asm_system_h-for-linus-20120328' of git://git.kernel.org/pub/scm...
[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 #include <linux/slab.h>
48 #include <linux/task_io_accounting_ops.h>
49
50 #include <linux/nfs_fs.h>
51 #include <linux/nfs_page.h>
52 #include <linux/sunrpc/clnt.h>
53
54 #include <asm/uaccess.h>
55 #include <linux/atomic.h>
56
57 #include "internal.h"
58 #include "iostat.h"
59
60 #define NFSDBG_FACILITY         NFSDBG_VFS
61
62 static struct kmem_cache *nfs_direct_cachep;
63
64 /*
65  * This represents a set of asynchronous requests that we're waiting on
66  */
67 struct nfs_direct_req {
68         struct kref             kref;           /* release manager */
69
70         /* I/O parameters */
71         struct nfs_open_context *ctx;           /* file open context info */
72         struct nfs_lock_context *l_ctx;         /* Lock context info */
73         struct kiocb *          iocb;           /* controlling i/o request */
74         struct inode *          inode;          /* target file of i/o */
75
76         /* completion state */
77         atomic_t                io_count;       /* i/os we're waiting for */
78         spinlock_t              lock;           /* protect completion state */
79         ssize_t                 count,          /* bytes actually processed */
80                                 error;          /* any reported error */
81         struct completion       completion;     /* wait for i/o completion */
82
83         /* commit state */
84         struct list_head        rewrite_list;   /* saved nfs_write_data structs */
85         struct nfs_write_data * commit_data;    /* special write_data for commits */
86         int                     flags;
87 #define NFS_ODIRECT_DO_COMMIT           (1)     /* an unstable reply was received */
88 #define NFS_ODIRECT_RESCHED_WRITES      (2)     /* write verification failed */
89         struct nfs_writeverf    verf;           /* unstable write verifier */
90 };
91
92 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
93 static const struct rpc_call_ops nfs_write_direct_ops;
94
95 static inline void get_dreq(struct nfs_direct_req *dreq)
96 {
97         atomic_inc(&dreq->io_count);
98 }
99
100 static inline int put_dreq(struct nfs_direct_req *dreq)
101 {
102         return atomic_dec_and_test(&dreq->io_count);
103 }
104
105 /**
106  * nfs_direct_IO - NFS address space operation for direct I/O
107  * @rw: direction (read or write)
108  * @iocb: target I/O control block
109  * @iov: array of vectors that define I/O buffer
110  * @pos: offset in file to begin the operation
111  * @nr_segs: size of iovec array
112  *
113  * The presence of this routine in the address space ops vector means
114  * the NFS client supports direct I/O.  However, we shunt off direct
115  * read and write requests before the VFS gets them, so this method
116  * should never be called.
117  */
118 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
119 {
120         dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
121                         iocb->ki_filp->f_path.dentry->d_name.name,
122                         (long long) pos, nr_segs);
123
124         return -EINVAL;
125 }
126
127 static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
128 {
129         unsigned int npages;
130         unsigned int i;
131
132         if (count == 0)
133                 return;
134         pages += (pgbase >> PAGE_SHIFT);
135         npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
136         for (i = 0; i < npages; i++) {
137                 struct page *page = pages[i];
138                 if (!PageCompound(page))
139                         set_page_dirty(page);
140         }
141 }
142
143 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
144 {
145         unsigned int i;
146         for (i = 0; i < npages; i++)
147                 page_cache_release(pages[i]);
148 }
149
150 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
151 {
152         struct nfs_direct_req *dreq;
153
154         dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
155         if (!dreq)
156                 return NULL;
157
158         kref_init(&dreq->kref);
159         kref_get(&dreq->kref);
160         init_completion(&dreq->completion);
161         INIT_LIST_HEAD(&dreq->rewrite_list);
162         dreq->iocb = NULL;
163         dreq->ctx = NULL;
164         dreq->l_ctx = NULL;
165         spin_lock_init(&dreq->lock);
166         atomic_set(&dreq->io_count, 0);
167         dreq->count = 0;
168         dreq->error = 0;
169         dreq->flags = 0;
170
171         return dreq;
172 }
173
174 static void nfs_direct_req_free(struct kref *kref)
175 {
176         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
177
178         if (dreq->l_ctx != NULL)
179                 nfs_put_lock_context(dreq->l_ctx);
180         if (dreq->ctx != NULL)
181                 put_nfs_open_context(dreq->ctx);
182         kmem_cache_free(nfs_direct_cachep, dreq);
183 }
184
185 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
186 {
187         kref_put(&dreq->kref, nfs_direct_req_free);
188 }
189
190 /*
191  * Collects and returns the final error value/byte-count.
192  */
193 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
194 {
195         ssize_t result = -EIOCBQUEUED;
196
197         /* Async requests don't wait here */
198         if (dreq->iocb)
199                 goto out;
200
201         result = wait_for_completion_killable(&dreq->completion);
202
203         if (!result)
204                 result = dreq->error;
205         if (!result)
206                 result = dreq->count;
207
208 out:
209         return (ssize_t) result;
210 }
211
212 /*
213  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
214  * the iocb is still valid here if this is a synchronous request.
215  */
216 static void nfs_direct_complete(struct nfs_direct_req *dreq)
217 {
218         if (dreq->iocb) {
219                 long res = (long) dreq->error;
220                 if (!res)
221                         res = (long) dreq->count;
222                 aio_complete(dreq->iocb, res, 0);
223         }
224         complete_all(&dreq->completion);
225
226         nfs_direct_req_release(dreq);
227 }
228
229 /*
230  * We must hold a reference to all the pages in this direct read request
231  * until the RPCs complete.  This could be long *after* we are woken up in
232  * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
233  */
234 static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
235 {
236         struct nfs_read_data *data = calldata;
237
238         nfs_readpage_result(task, data);
239 }
240
241 static void nfs_direct_read_release(void *calldata)
242 {
243
244         struct nfs_read_data *data = calldata;
245         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
246         int status = data->task.tk_status;
247
248         spin_lock(&dreq->lock);
249         if (unlikely(status < 0)) {
250                 dreq->error = status;
251                 spin_unlock(&dreq->lock);
252         } else {
253                 dreq->count += data->res.count;
254                 spin_unlock(&dreq->lock);
255                 nfs_direct_dirty_pages(data->pagevec,
256                                 data->args.pgbase,
257                                 data->res.count);
258         }
259         nfs_direct_release_pages(data->pagevec, data->npages);
260
261         if (put_dreq(dreq))
262                 nfs_direct_complete(dreq);
263         nfs_readdata_free(data);
264 }
265
266 static const struct rpc_call_ops nfs_read_direct_ops = {
267         .rpc_call_prepare = nfs_read_prepare,
268         .rpc_call_done = nfs_direct_read_result,
269         .rpc_release = nfs_direct_read_release,
270 };
271
272 /*
273  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
274  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
275  * bail and stop sending more reads.  Read length accounting is
276  * handled automatically by nfs_direct_read_result().  Otherwise, if
277  * no requests have been sent, just return an error.
278  */
279 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
280                                                 const struct iovec *iov,
281                                                 loff_t pos)
282 {
283         struct nfs_open_context *ctx = dreq->ctx;
284         struct inode *inode = ctx->dentry->d_inode;
285         unsigned long user_addr = (unsigned long)iov->iov_base;
286         size_t count = iov->iov_len;
287         size_t rsize = NFS_SERVER(inode)->rsize;
288         struct rpc_task *task;
289         struct rpc_message msg = {
290                 .rpc_cred = ctx->cred,
291         };
292         struct rpc_task_setup task_setup_data = {
293                 .rpc_client = NFS_CLIENT(inode),
294                 .rpc_message = &msg,
295                 .callback_ops = &nfs_read_direct_ops,
296                 .workqueue = nfsiod_workqueue,
297                 .flags = RPC_TASK_ASYNC,
298         };
299         unsigned int pgbase;
300         int result;
301         ssize_t started = 0;
302
303         do {
304                 struct nfs_read_data *data;
305                 size_t bytes;
306
307                 pgbase = user_addr & ~PAGE_MASK;
308                 bytes = min(rsize,count);
309
310                 result = -ENOMEM;
311                 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
312                 if (unlikely(!data))
313                         break;
314
315                 down_read(&current->mm->mmap_sem);
316                 result = get_user_pages(current, current->mm, user_addr,
317                                         data->npages, 1, 0, data->pagevec, NULL);
318                 up_read(&current->mm->mmap_sem);
319                 if (result < 0) {
320                         nfs_readdata_free(data);
321                         break;
322                 }
323                 if ((unsigned)result < data->npages) {
324                         bytes = result * PAGE_SIZE;
325                         if (bytes <= pgbase) {
326                                 nfs_direct_release_pages(data->pagevec, result);
327                                 nfs_readdata_free(data);
328                                 break;
329                         }
330                         bytes -= pgbase;
331                         data->npages = result;
332                 }
333
334                 get_dreq(dreq);
335
336                 data->req = (struct nfs_page *) dreq;
337                 data->inode = inode;
338                 data->cred = msg.rpc_cred;
339                 data->args.fh = NFS_FH(inode);
340                 data->args.context = ctx;
341                 data->args.lock_context = dreq->l_ctx;
342                 data->args.offset = pos;
343                 data->args.pgbase = pgbase;
344                 data->args.pages = data->pagevec;
345                 data->args.count = bytes;
346                 data->res.fattr = &data->fattr;
347                 data->res.eof = 0;
348                 data->res.count = bytes;
349                 nfs_fattr_init(&data->fattr);
350                 msg.rpc_argp = &data->args;
351                 msg.rpc_resp = &data->res;
352
353                 task_setup_data.task = &data->task;
354                 task_setup_data.callback_data = data;
355                 NFS_PROTO(inode)->read_setup(data, &msg);
356
357                 task = rpc_run_task(&task_setup_data);
358                 if (IS_ERR(task))
359                         break;
360                 rpc_put_task(task);
361
362                 dprintk("NFS: %5u initiated direct read call "
363                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
364                                 data->task.tk_pid,
365                                 inode->i_sb->s_id,
366                                 (long long)NFS_FILEID(inode),
367                                 bytes,
368                                 (unsigned long long)data->args.offset);
369
370                 started += bytes;
371                 user_addr += bytes;
372                 pos += bytes;
373                 /* FIXME: Remove this unnecessary math from final patch */
374                 pgbase += bytes;
375                 pgbase &= ~PAGE_MASK;
376                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
377
378                 count -= bytes;
379         } while (count != 0);
380
381         if (started)
382                 return started;
383         return result < 0 ? (ssize_t) result : -EFAULT;
384 }
385
386 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
387                                               const struct iovec *iov,
388                                               unsigned long nr_segs,
389                                               loff_t pos)
390 {
391         ssize_t result = -EINVAL;
392         size_t requested_bytes = 0;
393         unsigned long seg;
394
395         get_dreq(dreq);
396
397         for (seg = 0; seg < nr_segs; seg++) {
398                 const struct iovec *vec = &iov[seg];
399                 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
400                 if (result < 0)
401                         break;
402                 requested_bytes += result;
403                 if ((size_t)result < vec->iov_len)
404                         break;
405                 pos += vec->iov_len;
406         }
407
408         /*
409          * If no bytes were started, return the error, and let the
410          * generic layer handle the completion.
411          */
412         if (requested_bytes == 0) {
413                 nfs_direct_req_release(dreq);
414                 return result < 0 ? result : -EIO;
415         }
416
417         if (put_dreq(dreq))
418                 nfs_direct_complete(dreq);
419         return 0;
420 }
421
422 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
423                                unsigned long nr_segs, loff_t pos)
424 {
425         ssize_t result = -ENOMEM;
426         struct inode *inode = iocb->ki_filp->f_mapping->host;
427         struct nfs_direct_req *dreq;
428
429         dreq = nfs_direct_req_alloc();
430         if (dreq == NULL)
431                 goto out;
432
433         dreq->inode = inode;
434         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
435         dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
436         if (dreq->l_ctx == NULL)
437                 goto out_release;
438         if (!is_sync_kiocb(iocb))
439                 dreq->iocb = iocb;
440
441         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
442         if (!result)
443                 result = nfs_direct_wait(dreq);
444 out_release:
445         nfs_direct_req_release(dreq);
446 out:
447         return result;
448 }
449
450 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
451 {
452         while (!list_empty(&dreq->rewrite_list)) {
453                 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
454                 list_del(&data->pages);
455                 nfs_direct_release_pages(data->pagevec, data->npages);
456                 nfs_writedata_free(data);
457         }
458 }
459
460 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
461 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
462 {
463         struct inode *inode = dreq->inode;
464         struct list_head *p;
465         struct nfs_write_data *data;
466         struct rpc_task *task;
467         struct rpc_message msg = {
468                 .rpc_cred = dreq->ctx->cred,
469         };
470         struct rpc_task_setup task_setup_data = {
471                 .rpc_client = NFS_CLIENT(inode),
472                 .rpc_message = &msg,
473                 .callback_ops = &nfs_write_direct_ops,
474                 .workqueue = nfsiod_workqueue,
475                 .flags = RPC_TASK_ASYNC,
476         };
477
478         dreq->count = 0;
479         get_dreq(dreq);
480
481         list_for_each(p, &dreq->rewrite_list) {
482                 data = list_entry(p, struct nfs_write_data, pages);
483
484                 get_dreq(dreq);
485
486                 /* Use stable writes */
487                 data->args.stable = NFS_FILE_SYNC;
488
489                 /*
490                  * Reset data->res.
491                  */
492                 nfs_fattr_init(&data->fattr);
493                 data->res.count = data->args.count;
494                 memset(&data->verf, 0, sizeof(data->verf));
495
496                 /*
497                  * Reuse data->task; data->args should not have changed
498                  * since the original request was sent.
499                  */
500                 task_setup_data.task = &data->task;
501                 task_setup_data.callback_data = data;
502                 msg.rpc_argp = &data->args;
503                 msg.rpc_resp = &data->res;
504                 NFS_PROTO(inode)->write_setup(data, &msg);
505
506                 /*
507                  * We're called via an RPC callback, so BKL is already held.
508                  */
509                 task = rpc_run_task(&task_setup_data);
510                 if (!IS_ERR(task))
511                         rpc_put_task(task);
512
513                 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
514                                 data->task.tk_pid,
515                                 inode->i_sb->s_id,
516                                 (long long)NFS_FILEID(inode),
517                                 data->args.count,
518                                 (unsigned long long)data->args.offset);
519         }
520
521         if (put_dreq(dreq))
522                 nfs_direct_write_complete(dreq, inode);
523 }
524
525 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
526 {
527         struct nfs_write_data *data = calldata;
528
529         /* Call the NFS version-specific code */
530         NFS_PROTO(data->inode)->commit_done(task, data);
531 }
532
533 static void nfs_direct_commit_release(void *calldata)
534 {
535         struct nfs_write_data *data = calldata;
536         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
537         int status = data->task.tk_status;
538
539         if (status < 0) {
540                 dprintk("NFS: %5u commit failed with error %d.\n",
541                                 data->task.tk_pid, status);
542                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
543         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
544                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
545                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
546         }
547
548         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
549         nfs_direct_write_complete(dreq, data->inode);
550         nfs_commit_free(data);
551 }
552
553 static const struct rpc_call_ops nfs_commit_direct_ops = {
554         .rpc_call_prepare = nfs_write_prepare,
555         .rpc_call_done = nfs_direct_commit_result,
556         .rpc_release = nfs_direct_commit_release,
557 };
558
559 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
560 {
561         struct nfs_write_data *data = dreq->commit_data;
562         struct rpc_task *task;
563         struct rpc_message msg = {
564                 .rpc_argp = &data->args,
565                 .rpc_resp = &data->res,
566                 .rpc_cred = dreq->ctx->cred,
567         };
568         struct rpc_task_setup task_setup_data = {
569                 .task = &data->task,
570                 .rpc_client = NFS_CLIENT(dreq->inode),
571                 .rpc_message = &msg,
572                 .callback_ops = &nfs_commit_direct_ops,
573                 .callback_data = data,
574                 .workqueue = nfsiod_workqueue,
575                 .flags = RPC_TASK_ASYNC,
576         };
577
578         data->inode = dreq->inode;
579         data->cred = msg.rpc_cred;
580
581         data->args.fh = NFS_FH(data->inode);
582         data->args.offset = 0;
583         data->args.count = 0;
584         data->args.context = dreq->ctx;
585         data->args.lock_context = dreq->l_ctx;
586         data->res.count = 0;
587         data->res.fattr = &data->fattr;
588         data->res.verf = &data->verf;
589         nfs_fattr_init(&data->fattr);
590
591         NFS_PROTO(data->inode)->commit_setup(data, &msg);
592
593         /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
594         dreq->commit_data = NULL;
595
596         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
597
598         task = rpc_run_task(&task_setup_data);
599         if (!IS_ERR(task))
600                 rpc_put_task(task);
601 }
602
603 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
604 {
605         int flags = dreq->flags;
606
607         dreq->flags = 0;
608         switch (flags) {
609                 case NFS_ODIRECT_DO_COMMIT:
610                         nfs_direct_commit_schedule(dreq);
611                         break;
612                 case NFS_ODIRECT_RESCHED_WRITES:
613                         nfs_direct_write_reschedule(dreq);
614                         break;
615                 default:
616                         if (dreq->commit_data != NULL)
617                                 nfs_commit_free(dreq->commit_data);
618                         nfs_direct_free_writedata(dreq);
619                         nfs_zap_mapping(inode, inode->i_mapping);
620                         nfs_direct_complete(dreq);
621         }
622 }
623
624 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
625 {
626         dreq->commit_data = nfs_commitdata_alloc();
627         if (dreq->commit_data != NULL)
628                 dreq->commit_data->req = (struct nfs_page *) dreq;
629 }
630 #else
631 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
632 {
633         dreq->commit_data = NULL;
634 }
635
636 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
637 {
638         nfs_direct_free_writedata(dreq);
639         nfs_zap_mapping(inode, inode->i_mapping);
640         nfs_direct_complete(dreq);
641 }
642 #endif
643
644 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
645 {
646         struct nfs_write_data *data = calldata;
647
648         nfs_writeback_done(task, data);
649 }
650
651 /*
652  * NB: Return the value of the first error return code.  Subsequent
653  *     errors after the first one are ignored.
654  */
655 static void nfs_direct_write_release(void *calldata)
656 {
657         struct nfs_write_data *data = calldata;
658         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
659         int status = data->task.tk_status;
660
661         spin_lock(&dreq->lock);
662
663         if (unlikely(status < 0)) {
664                 /* An error has occurred, so we should not commit */
665                 dreq->flags = 0;
666                 dreq->error = status;
667         }
668         if (unlikely(dreq->error != 0))
669                 goto out_unlock;
670
671         dreq->count += data->res.count;
672
673         if (data->res.verf->committed != NFS_FILE_SYNC) {
674                 switch (dreq->flags) {
675                         case 0:
676                                 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
677                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
678                                 break;
679                         case NFS_ODIRECT_DO_COMMIT:
680                                 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
681                                         dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
682                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
683                                 }
684                 }
685         }
686 out_unlock:
687         spin_unlock(&dreq->lock);
688
689         if (put_dreq(dreq))
690                 nfs_direct_write_complete(dreq, data->inode);
691 }
692
693 static const struct rpc_call_ops nfs_write_direct_ops = {
694         .rpc_call_prepare = nfs_write_prepare,
695         .rpc_call_done = nfs_direct_write_result,
696         .rpc_release = nfs_direct_write_release,
697 };
698
699 /*
700  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
701  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
702  * bail and stop sending more writes.  Write length accounting is
703  * handled automatically by nfs_direct_write_result().  Otherwise, if
704  * no requests have been sent, just return an error.
705  */
706 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
707                                                  const struct iovec *iov,
708                                                  loff_t pos, int sync)
709 {
710         struct nfs_open_context *ctx = dreq->ctx;
711         struct inode *inode = ctx->dentry->d_inode;
712         unsigned long user_addr = (unsigned long)iov->iov_base;
713         size_t count = iov->iov_len;
714         struct rpc_task *task;
715         struct rpc_message msg = {
716                 .rpc_cred = ctx->cred,
717         };
718         struct rpc_task_setup task_setup_data = {
719                 .rpc_client = NFS_CLIENT(inode),
720                 .rpc_message = &msg,
721                 .callback_ops = &nfs_write_direct_ops,
722                 .workqueue = nfsiod_workqueue,
723                 .flags = RPC_TASK_ASYNC,
724         };
725         size_t wsize = NFS_SERVER(inode)->wsize;
726         unsigned int pgbase;
727         int result;
728         ssize_t started = 0;
729
730         do {
731                 struct nfs_write_data *data;
732                 size_t bytes;
733
734                 pgbase = user_addr & ~PAGE_MASK;
735                 bytes = min(wsize,count);
736
737                 result = -ENOMEM;
738                 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
739                 if (unlikely(!data))
740                         break;
741
742                 down_read(&current->mm->mmap_sem);
743                 result = get_user_pages(current, current->mm, user_addr,
744                                         data->npages, 0, 0, data->pagevec, NULL);
745                 up_read(&current->mm->mmap_sem);
746                 if (result < 0) {
747                         nfs_writedata_free(data);
748                         break;
749                 }
750                 if ((unsigned)result < data->npages) {
751                         bytes = result * PAGE_SIZE;
752                         if (bytes <= pgbase) {
753                                 nfs_direct_release_pages(data->pagevec, result);
754                                 nfs_writedata_free(data);
755                                 break;
756                         }
757                         bytes -= pgbase;
758                         data->npages = result;
759                 }
760
761                 get_dreq(dreq);
762
763                 list_move_tail(&data->pages, &dreq->rewrite_list);
764
765                 data->req = (struct nfs_page *) dreq;
766                 data->inode = inode;
767                 data->cred = msg.rpc_cred;
768                 data->args.fh = NFS_FH(inode);
769                 data->args.context = ctx;
770                 data->args.lock_context = dreq->l_ctx;
771                 data->args.offset = pos;
772                 data->args.pgbase = pgbase;
773                 data->args.pages = data->pagevec;
774                 data->args.count = bytes;
775                 data->args.stable = sync;
776                 data->res.fattr = &data->fattr;
777                 data->res.count = bytes;
778                 data->res.verf = &data->verf;
779                 nfs_fattr_init(&data->fattr);
780
781                 task_setup_data.task = &data->task;
782                 task_setup_data.callback_data = data;
783                 msg.rpc_argp = &data->args;
784                 msg.rpc_resp = &data->res;
785                 NFS_PROTO(inode)->write_setup(data, &msg);
786
787                 task = rpc_run_task(&task_setup_data);
788                 if (IS_ERR(task))
789                         break;
790                 rpc_put_task(task);
791
792                 dprintk("NFS: %5u initiated direct write call "
793                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
794                                 data->task.tk_pid,
795                                 inode->i_sb->s_id,
796                                 (long long)NFS_FILEID(inode),
797                                 bytes,
798                                 (unsigned long long)data->args.offset);
799
800                 started += bytes;
801                 user_addr += bytes;
802                 pos += bytes;
803
804                 /* FIXME: Remove this useless math from the final patch */
805                 pgbase += bytes;
806                 pgbase &= ~PAGE_MASK;
807                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
808
809                 count -= bytes;
810         } while (count != 0);
811
812         if (started)
813                 return started;
814         return result < 0 ? (ssize_t) result : -EFAULT;
815 }
816
817 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
818                                                const struct iovec *iov,
819                                                unsigned long nr_segs,
820                                                loff_t pos, int sync)
821 {
822         ssize_t result = 0;
823         size_t requested_bytes = 0;
824         unsigned long seg;
825
826         get_dreq(dreq);
827
828         for (seg = 0; seg < nr_segs; seg++) {
829                 const struct iovec *vec = &iov[seg];
830                 result = nfs_direct_write_schedule_segment(dreq, vec,
831                                                            pos, sync);
832                 if (result < 0)
833                         break;
834                 requested_bytes += result;
835                 if ((size_t)result < vec->iov_len)
836                         break;
837                 pos += vec->iov_len;
838         }
839
840         /*
841          * If no bytes were started, return the error, and let the
842          * generic layer handle the completion.
843          */
844         if (requested_bytes == 0) {
845                 nfs_direct_req_release(dreq);
846                 return result < 0 ? result : -EIO;
847         }
848
849         if (put_dreq(dreq))
850                 nfs_direct_write_complete(dreq, dreq->inode);
851         return 0;
852 }
853
854 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
855                                 unsigned long nr_segs, loff_t pos,
856                                 size_t count)
857 {
858         ssize_t result = -ENOMEM;
859         struct inode *inode = iocb->ki_filp->f_mapping->host;
860         struct nfs_direct_req *dreq;
861         size_t wsize = NFS_SERVER(inode)->wsize;
862         int sync = NFS_UNSTABLE;
863
864         dreq = nfs_direct_req_alloc();
865         if (!dreq)
866                 goto out;
867         nfs_alloc_commit_data(dreq);
868
869         if (dreq->commit_data == NULL || count <= wsize)
870                 sync = NFS_FILE_SYNC;
871
872         dreq->inode = inode;
873         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
874         dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
875         if (dreq->l_ctx == NULL)
876                 goto out_release;
877         if (!is_sync_kiocb(iocb))
878                 dreq->iocb = iocb;
879
880         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
881         if (!result)
882                 result = nfs_direct_wait(dreq);
883 out_release:
884         nfs_direct_req_release(dreq);
885 out:
886         return result;
887 }
888
889 /**
890  * nfs_file_direct_read - file direct read operation for NFS files
891  * @iocb: target I/O control block
892  * @iov: vector of user buffers into which to read data
893  * @nr_segs: size of iov vector
894  * @pos: byte offset in file where reading starts
895  *
896  * We use this function for direct reads instead of calling
897  * generic_file_aio_read() in order to avoid gfar's check to see if
898  * the request starts before the end of the file.  For that check
899  * to work, we must generate a GETATTR before each direct read, and
900  * even then there is a window between the GETATTR and the subsequent
901  * READ where the file size could change.  Our preference is simply
902  * to do all reads the application wants, and the server will take
903  * care of managing the end of file boundary.
904  *
905  * This function also eliminates unnecessarily updating the file's
906  * atime locally, as the NFS server sets the file's atime, and this
907  * client must read the updated atime from the server back into its
908  * cache.
909  */
910 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
911                                 unsigned long nr_segs, loff_t pos)
912 {
913         ssize_t retval = -EINVAL;
914         struct file *file = iocb->ki_filp;
915         struct address_space *mapping = file->f_mapping;
916         size_t count;
917
918         count = iov_length(iov, nr_segs);
919         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
920
921         dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
922                 file->f_path.dentry->d_parent->d_name.name,
923                 file->f_path.dentry->d_name.name,
924                 count, (long long) pos);
925
926         retval = 0;
927         if (!count)
928                 goto out;
929
930         retval = nfs_sync_mapping(mapping);
931         if (retval)
932                 goto out;
933
934         task_io_account_read(count);
935
936         retval = nfs_direct_read(iocb, iov, nr_segs, pos);
937         if (retval > 0)
938                 iocb->ki_pos = pos + retval;
939
940 out:
941         return retval;
942 }
943
944 /**
945  * nfs_file_direct_write - file direct write operation for NFS files
946  * @iocb: target I/O control block
947  * @iov: vector of user buffers from which to write data
948  * @nr_segs: size of iov vector
949  * @pos: byte offset in file where writing starts
950  *
951  * We use this function for direct writes instead of calling
952  * generic_file_aio_write() in order to avoid taking the inode
953  * semaphore and updating the i_size.  The NFS server will set
954  * the new i_size and this client must read the updated size
955  * back into its cache.  We let the server do generic write
956  * parameter checking and report problems.
957  *
958  * We eliminate local atime updates, see direct read above.
959  *
960  * We avoid unnecessary page cache invalidations for normal cached
961  * readers of this file.
962  *
963  * Note that O_APPEND is not supported for NFS direct writes, as there
964  * is no atomic O_APPEND write facility in the NFS protocol.
965  */
966 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
967                                 unsigned long nr_segs, loff_t pos)
968 {
969         ssize_t retval = -EINVAL;
970         struct file *file = iocb->ki_filp;
971         struct address_space *mapping = file->f_mapping;
972         size_t count;
973
974         count = iov_length(iov, nr_segs);
975         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
976
977         dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
978                 file->f_path.dentry->d_parent->d_name.name,
979                 file->f_path.dentry->d_name.name,
980                 count, (long long) pos);
981
982         retval = generic_write_checks(file, &pos, &count, 0);
983         if (retval)
984                 goto out;
985
986         retval = -EINVAL;
987         if ((ssize_t) count < 0)
988                 goto out;
989         retval = 0;
990         if (!count)
991                 goto out;
992
993         retval = nfs_sync_mapping(mapping);
994         if (retval)
995                 goto out;
996
997         task_io_account_write(count);
998
999         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
1000
1001         if (retval > 0)
1002                 iocb->ki_pos = pos + retval;
1003
1004 out:
1005         return retval;
1006 }
1007
1008 /**
1009  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1010  *
1011  */
1012 int __init nfs_init_directcache(void)
1013 {
1014         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1015                                                 sizeof(struct nfs_direct_req),
1016                                                 0, (SLAB_RECLAIM_ACCOUNT|
1017                                                         SLAB_MEM_SPREAD),
1018                                                 NULL);
1019         if (nfs_direct_cachep == NULL)
1020                 return -ENOMEM;
1021
1022         return 0;
1023 }
1024
1025 /**
1026  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1027  *
1028  */
1029 void nfs_destroy_directcache(void)
1030 {
1031         kmem_cache_destroy(nfs_direct_cachep);
1032 }