NFS: Ensure that rpc_run_task() errors are propagated back to the caller
[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_release(calldata);
259 }
260
261 static const struct rpc_call_ops nfs_read_direct_ops = {
262         .rpc_call_done = nfs_direct_read_result,
263         .rpc_release = nfs_direct_read_release,
264 };
265
266 /*
267  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
268  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
269  * bail and stop sending more reads.  Read length accounting is
270  * handled automatically by nfs_direct_read_result().  Otherwise, if
271  * no requests have been sent, just return an error.
272  */
273 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
274                                                 const struct iovec *iov,
275                                                 loff_t pos)
276 {
277         struct nfs_open_context *ctx = dreq->ctx;
278         struct inode *inode = ctx->path.dentry->d_inode;
279         unsigned long user_addr = (unsigned long)iov->iov_base;
280         size_t count = iov->iov_len;
281         size_t rsize = NFS_SERVER(inode)->rsize;
282         struct rpc_task *task;
283         struct rpc_message msg = {
284                 .rpc_cred = ctx->cred,
285         };
286         struct rpc_task_setup task_setup_data = {
287                 .rpc_client = NFS_CLIENT(inode),
288                 .rpc_message = &msg,
289                 .callback_ops = &nfs_read_direct_ops,
290                 .workqueue = nfsiod_workqueue,
291                 .flags = RPC_TASK_ASYNC,
292         };
293         unsigned int pgbase;
294         int result;
295         ssize_t started = 0;
296
297         do {
298                 struct nfs_read_data *data;
299                 size_t bytes;
300
301                 pgbase = user_addr & ~PAGE_MASK;
302                 bytes = min(rsize,count);
303
304                 result = -ENOMEM;
305                 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
306                 if (unlikely(!data))
307                         break;
308
309                 down_read(&current->mm->mmap_sem);
310                 result = get_user_pages(current, current->mm, user_addr,
311                                         data->npages, 1, 0, data->pagevec, NULL);
312                 up_read(&current->mm->mmap_sem);
313                 if (result < 0) {
314                         nfs_readdata_release(data);
315                         break;
316                 }
317                 if ((unsigned)result < data->npages) {
318                         bytes = result * PAGE_SIZE;
319                         if (bytes <= pgbase) {
320                                 nfs_direct_release_pages(data->pagevec, result);
321                                 nfs_readdata_release(data);
322                                 break;
323                         }
324                         bytes -= pgbase;
325                         data->npages = result;
326                 }
327
328                 get_dreq(dreq);
329
330                 data->req = (struct nfs_page *) dreq;
331                 data->inode = inode;
332                 data->cred = msg.rpc_cred;
333                 data->args.fh = NFS_FH(inode);
334                 data->args.context = get_nfs_open_context(ctx);
335                 data->args.offset = pos;
336                 data->args.pgbase = pgbase;
337                 data->args.pages = data->pagevec;
338                 data->args.count = bytes;
339                 data->res.fattr = &data->fattr;
340                 data->res.eof = 0;
341                 data->res.count = bytes;
342                 msg.rpc_argp = &data->args;
343                 msg.rpc_resp = &data->res;
344
345                 task_setup_data.task = &data->task;
346                 task_setup_data.callback_data = data;
347                 NFS_PROTO(inode)->read_setup(data, &msg);
348
349                 task = rpc_run_task(&task_setup_data);
350                 if (IS_ERR(task))
351                         break;
352                 rpc_put_task(task);
353
354                 dprintk("NFS: %5u initiated direct read call "
355                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
356                                 data->task.tk_pid,
357                                 inode->i_sb->s_id,
358                                 (long long)NFS_FILEID(inode),
359                                 bytes,
360                                 (unsigned long long)data->args.offset);
361
362                 started += bytes;
363                 user_addr += bytes;
364                 pos += bytes;
365                 /* FIXME: Remove this unnecessary math from final patch */
366                 pgbase += bytes;
367                 pgbase &= ~PAGE_MASK;
368                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
369
370                 count -= bytes;
371         } while (count != 0);
372
373         if (started)
374                 return started;
375         return result < 0 ? (ssize_t) result : -EFAULT;
376 }
377
378 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
379                                               const struct iovec *iov,
380                                               unsigned long nr_segs,
381                                               loff_t pos)
382 {
383         ssize_t result = -EINVAL;
384         size_t requested_bytes = 0;
385         unsigned long seg;
386
387         get_dreq(dreq);
388
389         for (seg = 0; seg < nr_segs; seg++) {
390                 const struct iovec *vec = &iov[seg];
391                 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
392                 if (result < 0)
393                         break;
394                 requested_bytes += result;
395                 if ((size_t)result < vec->iov_len)
396                         break;
397                 pos += vec->iov_len;
398         }
399
400         if (put_dreq(dreq))
401                 nfs_direct_complete(dreq);
402
403         if (requested_bytes != 0)
404                 return 0;
405
406         if (result < 0)
407                 return result;
408         return -EIO;
409 }
410
411 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
412                                unsigned long nr_segs, loff_t pos)
413 {
414         ssize_t result = 0;
415         struct inode *inode = iocb->ki_filp->f_mapping->host;
416         struct nfs_direct_req *dreq;
417
418         dreq = nfs_direct_req_alloc();
419         if (!dreq)
420                 return -ENOMEM;
421
422         dreq->inode = inode;
423         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
424         if (!is_sync_kiocb(iocb))
425                 dreq->iocb = iocb;
426
427         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
428         if (!result)
429                 result = nfs_direct_wait(dreq);
430         nfs_direct_req_release(dreq);
431
432         return result;
433 }
434
435 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
436 {
437         while (!list_empty(&dreq->rewrite_list)) {
438                 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
439                 list_del(&data->pages);
440                 nfs_direct_release_pages(data->pagevec, data->npages);
441                 nfs_writedata_release(data);
442         }
443 }
444
445 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
446 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
447 {
448         struct inode *inode = dreq->inode;
449         struct list_head *p;
450         struct nfs_write_data *data;
451         struct rpc_task *task;
452         struct rpc_message msg = {
453                 .rpc_cred = dreq->ctx->cred,
454         };
455         struct rpc_task_setup task_setup_data = {
456                 .rpc_client = NFS_CLIENT(inode),
457                 .callback_ops = &nfs_write_direct_ops,
458                 .workqueue = nfsiod_workqueue,
459                 .flags = RPC_TASK_ASYNC,
460         };
461
462         dreq->count = 0;
463         get_dreq(dreq);
464
465         list_for_each(p, &dreq->rewrite_list) {
466                 data = list_entry(p, struct nfs_write_data, pages);
467
468                 get_dreq(dreq);
469
470                 /* Use stable writes */
471                 data->args.stable = NFS_FILE_SYNC;
472
473                 /*
474                  * Reset data->res.
475                  */
476                 nfs_fattr_init(&data->fattr);
477                 data->res.count = data->args.count;
478                 memset(&data->verf, 0, sizeof(data->verf));
479
480                 /*
481                  * Reuse data->task; data->args should not have changed
482                  * since the original request was sent.
483                  */
484                 task_setup_data.task = &data->task;
485                 task_setup_data.callback_data = data;
486                 msg.rpc_argp = &data->args;
487                 msg.rpc_resp = &data->res;
488                 NFS_PROTO(inode)->write_setup(data, &msg);
489
490                 /*
491                  * We're called via an RPC callback, so BKL is already held.
492                  */
493                 task = rpc_run_task(&task_setup_data);
494                 if (!IS_ERR(task))
495                         rpc_put_task(task);
496
497                 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
498                                 data->task.tk_pid,
499                                 inode->i_sb->s_id,
500                                 (long long)NFS_FILEID(inode),
501                                 data->args.count,
502                                 (unsigned long long)data->args.offset);
503         }
504
505         if (put_dreq(dreq))
506                 nfs_direct_write_complete(dreq, inode);
507 }
508
509 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
510 {
511         struct nfs_write_data *data = calldata;
512
513         /* Call the NFS version-specific code */
514         NFS_PROTO(data->inode)->commit_done(task, data);
515 }
516
517 static void nfs_direct_commit_release(void *calldata)
518 {
519         struct nfs_write_data *data = calldata;
520         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
521         int status = data->task.tk_status;
522
523         if (status < 0) {
524                 dprintk("NFS: %5u commit failed with error %d.\n",
525                                 data->task.tk_pid, status);
526                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
527         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
528                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
529                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
530         }
531
532         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
533         nfs_direct_write_complete(dreq, data->inode);
534         nfs_commitdata_release(calldata);
535 }
536
537 static const struct rpc_call_ops nfs_commit_direct_ops = {
538         .rpc_call_done = nfs_direct_commit_result,
539         .rpc_release = nfs_direct_commit_release,
540 };
541
542 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
543 {
544         struct nfs_write_data *data = dreq->commit_data;
545         struct rpc_task *task;
546         struct rpc_message msg = {
547                 .rpc_argp = &data->args,
548                 .rpc_resp = &data->res,
549                 .rpc_cred = dreq->ctx->cred,
550         };
551         struct rpc_task_setup task_setup_data = {
552                 .task = &data->task,
553                 .rpc_client = NFS_CLIENT(dreq->inode),
554                 .rpc_message = &msg,
555                 .callback_ops = &nfs_commit_direct_ops,
556                 .callback_data = data,
557                 .workqueue = nfsiod_workqueue,
558                 .flags = RPC_TASK_ASYNC,
559         };
560
561         data->inode = dreq->inode;
562         data->cred = msg.rpc_cred;
563
564         data->args.fh = NFS_FH(data->inode);
565         data->args.offset = 0;
566         data->args.count = 0;
567         data->args.context = get_nfs_open_context(dreq->ctx);
568         data->res.count = 0;
569         data->res.fattr = &data->fattr;
570         data->res.verf = &data->verf;
571
572         NFS_PROTO(data->inode)->commit_setup(data, &msg);
573
574         /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
575         dreq->commit_data = NULL;
576
577         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
578
579         task = rpc_run_task(&task_setup_data);
580         if (!IS_ERR(task))
581                 rpc_put_task(task);
582 }
583
584 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
585 {
586         int flags = dreq->flags;
587
588         dreq->flags = 0;
589         switch (flags) {
590                 case NFS_ODIRECT_DO_COMMIT:
591                         nfs_direct_commit_schedule(dreq);
592                         break;
593                 case NFS_ODIRECT_RESCHED_WRITES:
594                         nfs_direct_write_reschedule(dreq);
595                         break;
596                 default:
597                         if (dreq->commit_data != NULL)
598                                 nfs_commit_free(dreq->commit_data);
599                         nfs_direct_free_writedata(dreq);
600                         nfs_zap_mapping(inode, inode->i_mapping);
601                         nfs_direct_complete(dreq);
602         }
603 }
604
605 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
606 {
607         dreq->commit_data = nfs_commitdata_alloc();
608         if (dreq->commit_data != NULL)
609                 dreq->commit_data->req = (struct nfs_page *) dreq;
610 }
611 #else
612 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
613 {
614         dreq->commit_data = NULL;
615 }
616
617 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
618 {
619         nfs_direct_free_writedata(dreq);
620         nfs_zap_mapping(inode, inode->i_mapping);
621         nfs_direct_complete(dreq);
622 }
623 #endif
624
625 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
626 {
627         struct nfs_write_data *data = calldata;
628
629         if (nfs_writeback_done(task, data) != 0)
630                 return;
631 }
632
633 /*
634  * NB: Return the value of the first error return code.  Subsequent
635  *     errors after the first one are ignored.
636  */
637 static void nfs_direct_write_release(void *calldata)
638 {
639         struct nfs_write_data *data = calldata;
640         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
641         int status = data->task.tk_status;
642
643         spin_lock(&dreq->lock);
644
645         if (unlikely(status < 0)) {
646                 /* An error has occurred, so we should not commit */
647                 dreq->flags = 0;
648                 dreq->error = status;
649         }
650         if (unlikely(dreq->error != 0))
651                 goto out_unlock;
652
653         dreq->count += data->res.count;
654
655         if (data->res.verf->committed != NFS_FILE_SYNC) {
656                 switch (dreq->flags) {
657                         case 0:
658                                 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
659                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
660                                 break;
661                         case NFS_ODIRECT_DO_COMMIT:
662                                 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
663                                         dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
664                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
665                                 }
666                 }
667         }
668 out_unlock:
669         spin_unlock(&dreq->lock);
670
671         if (put_dreq(dreq))
672                 nfs_direct_write_complete(dreq, data->inode);
673 }
674
675 static const struct rpc_call_ops nfs_write_direct_ops = {
676         .rpc_call_done = nfs_direct_write_result,
677         .rpc_release = nfs_direct_write_release,
678 };
679
680 /*
681  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
682  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
683  * bail and stop sending more writes.  Write length accounting is
684  * handled automatically by nfs_direct_write_result().  Otherwise, if
685  * no requests have been sent, just return an error.
686  */
687 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
688                                                  const struct iovec *iov,
689                                                  loff_t pos, int sync)
690 {
691         struct nfs_open_context *ctx = dreq->ctx;
692         struct inode *inode = ctx->path.dentry->d_inode;
693         unsigned long user_addr = (unsigned long)iov->iov_base;
694         size_t count = iov->iov_len;
695         struct rpc_task *task;
696         struct rpc_message msg = {
697                 .rpc_cred = ctx->cred,
698         };
699         struct rpc_task_setup task_setup_data = {
700                 .rpc_client = NFS_CLIENT(inode),
701                 .rpc_message = &msg,
702                 .callback_ops = &nfs_write_direct_ops,
703                 .workqueue = nfsiod_workqueue,
704                 .flags = RPC_TASK_ASYNC,
705         };
706         size_t wsize = NFS_SERVER(inode)->wsize;
707         unsigned int pgbase;
708         int result;
709         ssize_t started = 0;
710
711         do {
712                 struct nfs_write_data *data;
713                 size_t bytes;
714
715                 pgbase = user_addr & ~PAGE_MASK;
716                 bytes = min(wsize,count);
717
718                 result = -ENOMEM;
719                 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
720                 if (unlikely(!data))
721                         break;
722
723                 down_read(&current->mm->mmap_sem);
724                 result = get_user_pages(current, current->mm, user_addr,
725                                         data->npages, 0, 0, data->pagevec, NULL);
726                 up_read(&current->mm->mmap_sem);
727                 if (result < 0) {
728                         nfs_writedata_release(data);
729                         break;
730                 }
731                 if ((unsigned)result < data->npages) {
732                         bytes = result * PAGE_SIZE;
733                         if (bytes <= pgbase) {
734                                 nfs_direct_release_pages(data->pagevec, result);
735                                 nfs_writedata_release(data);
736                                 break;
737                         }
738                         bytes -= pgbase;
739                         data->npages = result;
740                 }
741
742                 get_dreq(dreq);
743
744                 list_move_tail(&data->pages, &dreq->rewrite_list);
745
746                 data->req = (struct nfs_page *) dreq;
747                 data->inode = inode;
748                 data->cred = msg.rpc_cred;
749                 data->args.fh = NFS_FH(inode);
750                 data->args.context = get_nfs_open_context(ctx);
751                 data->args.offset = pos;
752                 data->args.pgbase = pgbase;
753                 data->args.pages = data->pagevec;
754                 data->args.count = bytes;
755                 data->args.stable = sync;
756                 data->res.fattr = &data->fattr;
757                 data->res.count = bytes;
758                 data->res.verf = &data->verf;
759
760                 task_setup_data.task = &data->task;
761                 task_setup_data.callback_data = data;
762                 msg.rpc_argp = &data->args;
763                 msg.rpc_resp = &data->res;
764                 NFS_PROTO(inode)->write_setup(data, &msg);
765
766                 task = rpc_run_task(&task_setup_data);
767                 if (IS_ERR(task))
768                         break;
769                 rpc_put_task(task);
770
771                 dprintk("NFS: %5u initiated direct write call "
772                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
773                                 data->task.tk_pid,
774                                 inode->i_sb->s_id,
775                                 (long long)NFS_FILEID(inode),
776                                 bytes,
777                                 (unsigned long long)data->args.offset);
778
779                 started += bytes;
780                 user_addr += bytes;
781                 pos += bytes;
782
783                 /* FIXME: Remove this useless math from the final patch */
784                 pgbase += bytes;
785                 pgbase &= ~PAGE_MASK;
786                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
787
788                 count -= bytes;
789         } while (count != 0);
790
791         if (started)
792                 return started;
793         return result < 0 ? (ssize_t) result : -EFAULT;
794 }
795
796 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
797                                                const struct iovec *iov,
798                                                unsigned long nr_segs,
799                                                loff_t pos, int sync)
800 {
801         ssize_t result = 0;
802         size_t requested_bytes = 0;
803         unsigned long seg;
804
805         get_dreq(dreq);
806
807         for (seg = 0; seg < nr_segs; seg++) {
808                 const struct iovec *vec = &iov[seg];
809                 result = nfs_direct_write_schedule_segment(dreq, vec,
810                                                            pos, sync);
811                 if (result < 0)
812                         break;
813                 requested_bytes += result;
814                 if ((size_t)result < vec->iov_len)
815                         break;
816                 pos += vec->iov_len;
817         }
818
819         if (put_dreq(dreq))
820                 nfs_direct_write_complete(dreq, dreq->inode);
821
822         if (requested_bytes != 0)
823                 return 0;
824
825         if (result < 0)
826                 return result;
827         return -EIO;
828 }
829
830 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
831                                 unsigned long nr_segs, loff_t pos,
832                                 size_t count)
833 {
834         ssize_t result = 0;
835         struct inode *inode = iocb->ki_filp->f_mapping->host;
836         struct nfs_direct_req *dreq;
837         size_t wsize = NFS_SERVER(inode)->wsize;
838         int sync = NFS_UNSTABLE;
839
840         dreq = nfs_direct_req_alloc();
841         if (!dreq)
842                 return -ENOMEM;
843         nfs_alloc_commit_data(dreq);
844
845         if (dreq->commit_data == NULL || count < wsize)
846                 sync = NFS_FILE_SYNC;
847
848         dreq->inode = inode;
849         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
850         if (!is_sync_kiocb(iocb))
851                 dreq->iocb = iocb;
852
853         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
854         if (!result)
855                 result = nfs_direct_wait(dreq);
856         nfs_direct_req_release(dreq);
857
858         return result;
859 }
860
861 /**
862  * nfs_file_direct_read - file direct read operation for NFS files
863  * @iocb: target I/O control block
864  * @iov: vector of user buffers into which to read data
865  * @nr_segs: size of iov vector
866  * @pos: byte offset in file where reading starts
867  *
868  * We use this function for direct reads instead of calling
869  * generic_file_aio_read() in order to avoid gfar's check to see if
870  * the request starts before the end of the file.  For that check
871  * to work, we must generate a GETATTR before each direct read, and
872  * even then there is a window between the GETATTR and the subsequent
873  * READ where the file size could change.  Our preference is simply
874  * to do all reads the application wants, and the server will take
875  * care of managing the end of file boundary.
876  *
877  * This function also eliminates unnecessarily updating the file's
878  * atime locally, as the NFS server sets the file's atime, and this
879  * client must read the updated atime from the server back into its
880  * cache.
881  */
882 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
883                                 unsigned long nr_segs, loff_t pos)
884 {
885         ssize_t retval = -EINVAL;
886         struct file *file = iocb->ki_filp;
887         struct address_space *mapping = file->f_mapping;
888         size_t count;
889
890         count = iov_length(iov, nr_segs);
891         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
892
893         dprintk("nfs: direct read(%s/%s, %zd@%Ld)\n",
894                 file->f_path.dentry->d_parent->d_name.name,
895                 file->f_path.dentry->d_name.name,
896                 count, (long long) pos);
897
898         retval = 0;
899         if (!count)
900                 goto out;
901
902         retval = nfs_sync_mapping(mapping);
903         if (retval)
904                 goto out;
905
906         retval = nfs_direct_read(iocb, iov, nr_segs, pos);
907         if (retval > 0)
908                 iocb->ki_pos = pos + retval;
909
910 out:
911         return retval;
912 }
913
914 /**
915  * nfs_file_direct_write - file direct write operation for NFS files
916  * @iocb: target I/O control block
917  * @iov: vector of user buffers from which to write data
918  * @nr_segs: size of iov vector
919  * @pos: byte offset in file where writing starts
920  *
921  * We use this function for direct writes instead of calling
922  * generic_file_aio_write() in order to avoid taking the inode
923  * semaphore and updating the i_size.  The NFS server will set
924  * the new i_size and this client must read the updated size
925  * back into its cache.  We let the server do generic write
926  * parameter checking and report problems.
927  *
928  * We also avoid an unnecessary invocation of generic_osync_inode(),
929  * as it is fairly meaningless to sync the metadata of an NFS file.
930  *
931  * We eliminate local atime updates, see direct read above.
932  *
933  * We avoid unnecessary page cache invalidations for normal cached
934  * readers of this file.
935  *
936  * Note that O_APPEND is not supported for NFS direct writes, as there
937  * is no atomic O_APPEND write facility in the NFS protocol.
938  */
939 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
940                                 unsigned long nr_segs, loff_t pos)
941 {
942         ssize_t retval = -EINVAL;
943         struct file *file = iocb->ki_filp;
944         struct address_space *mapping = file->f_mapping;
945         size_t count;
946
947         count = iov_length(iov, nr_segs);
948         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
949
950         dfprintk(VFS, "nfs: direct write(%s/%s, %zd@%Ld)\n",
951                 file->f_path.dentry->d_parent->d_name.name,
952                 file->f_path.dentry->d_name.name,
953                 count, (long long) pos);
954
955         retval = generic_write_checks(file, &pos, &count, 0);
956         if (retval)
957                 goto out;
958
959         retval = -EINVAL;
960         if ((ssize_t) count < 0)
961                 goto out;
962         retval = 0;
963         if (!count)
964                 goto out;
965
966         retval = nfs_sync_mapping(mapping);
967         if (retval)
968                 goto out;
969
970         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
971
972         if (retval > 0)
973                 iocb->ki_pos = pos + retval;
974
975 out:
976         return retval;
977 }
978
979 /**
980  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
981  *
982  */
983 int __init nfs_init_directcache(void)
984 {
985         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
986                                                 sizeof(struct nfs_direct_req),
987                                                 0, (SLAB_RECLAIM_ACCOUNT|
988                                                         SLAB_MEM_SPREAD),
989                                                 NULL);
990         if (nfs_direct_cachep == NULL)
991                 return -ENOMEM;
992
993         return 0;
994 }
995
996 /**
997  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
998  *
999  */
1000 void nfs_destroy_directcache(void)
1001 {
1002         kmem_cache_destroy(nfs_direct_cachep);
1003 }