abf8e0286e3511a1e9f593bcf4a0ac534bb3d878
[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                         rpc_put_task(task);
352
353                 dprintk("NFS: %5u initiated direct read call "
354                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
355                                 data->task.tk_pid,
356                                 inode->i_sb->s_id,
357                                 (long long)NFS_FILEID(inode),
358                                 bytes,
359                                 (unsigned long long)data->args.offset);
360
361                 started += bytes;
362                 user_addr += bytes;
363                 pos += bytes;
364                 /* FIXME: Remove this unnecessary math from final patch */
365                 pgbase += bytes;
366                 pgbase &= ~PAGE_MASK;
367                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
368
369                 count -= bytes;
370         } while (count != 0);
371
372         if (started)
373                 return started;
374         return result < 0 ? (ssize_t) result : -EFAULT;
375 }
376
377 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
378                                               const struct iovec *iov,
379                                               unsigned long nr_segs,
380                                               loff_t pos)
381 {
382         ssize_t result = -EINVAL;
383         size_t requested_bytes = 0;
384         unsigned long seg;
385
386         get_dreq(dreq);
387
388         for (seg = 0; seg < nr_segs; seg++) {
389                 const struct iovec *vec = &iov[seg];
390                 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
391                 if (result < 0)
392                         break;
393                 requested_bytes += result;
394                 if ((size_t)result < vec->iov_len)
395                         break;
396                 pos += vec->iov_len;
397         }
398
399         if (put_dreq(dreq))
400                 nfs_direct_complete(dreq);
401
402         if (requested_bytes != 0)
403                 return 0;
404
405         if (result < 0)
406                 return result;
407         return -EIO;
408 }
409
410 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
411                                unsigned long nr_segs, loff_t pos)
412 {
413         ssize_t result = 0;
414         struct inode *inode = iocb->ki_filp->f_mapping->host;
415         struct nfs_direct_req *dreq;
416
417         dreq = nfs_direct_req_alloc();
418         if (!dreq)
419                 return -ENOMEM;
420
421         dreq->inode = inode;
422         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
423         if (!is_sync_kiocb(iocb))
424                 dreq->iocb = iocb;
425
426         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
427         if (!result)
428                 result = nfs_direct_wait(dreq);
429         nfs_direct_req_release(dreq);
430
431         return result;
432 }
433
434 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
435 {
436         while (!list_empty(&dreq->rewrite_list)) {
437                 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
438                 list_del(&data->pages);
439                 nfs_direct_release_pages(data->pagevec, data->npages);
440                 nfs_writedata_release(data);
441         }
442 }
443
444 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
445 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
446 {
447         struct inode *inode = dreq->inode;
448         struct list_head *p;
449         struct nfs_write_data *data;
450         struct rpc_task *task;
451         struct rpc_message msg = {
452                 .rpc_cred = dreq->ctx->cred,
453         };
454         struct rpc_task_setup task_setup_data = {
455                 .rpc_client = NFS_CLIENT(inode),
456                 .callback_ops = &nfs_write_direct_ops,
457                 .workqueue = nfsiod_workqueue,
458                 .flags = RPC_TASK_ASYNC,
459         };
460
461         dreq->count = 0;
462         get_dreq(dreq);
463
464         list_for_each(p, &dreq->rewrite_list) {
465                 data = list_entry(p, struct nfs_write_data, pages);
466
467                 get_dreq(dreq);
468
469                 /* Use stable writes */
470                 data->args.stable = NFS_FILE_SYNC;
471
472                 /*
473                  * Reset data->res.
474                  */
475                 nfs_fattr_init(&data->fattr);
476                 data->res.count = data->args.count;
477                 memset(&data->verf, 0, sizeof(data->verf));
478
479                 /*
480                  * Reuse data->task; data->args should not have changed
481                  * since the original request was sent.
482                  */
483                 task_setup_data.task = &data->task;
484                 task_setup_data.callback_data = data;
485                 msg.rpc_argp = &data->args;
486                 msg.rpc_resp = &data->res;
487                 NFS_PROTO(inode)->write_setup(data, &msg);
488
489                 /*
490                  * We're called via an RPC callback, so BKL is already held.
491                  */
492                 task = rpc_run_task(&task_setup_data);
493                 if (!IS_ERR(task))
494                         rpc_put_task(task);
495
496                 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
497                                 data->task.tk_pid,
498                                 inode->i_sb->s_id,
499                                 (long long)NFS_FILEID(inode),
500                                 data->args.count,
501                                 (unsigned long long)data->args.offset);
502         }
503
504         if (put_dreq(dreq))
505                 nfs_direct_write_complete(dreq, inode);
506 }
507
508 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
509 {
510         struct nfs_write_data *data = calldata;
511
512         /* Call the NFS version-specific code */
513         NFS_PROTO(data->inode)->commit_done(task, data);
514 }
515
516 static void nfs_direct_commit_release(void *calldata)
517 {
518         struct nfs_write_data *data = calldata;
519         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
520         int status = data->task.tk_status;
521
522         if (status < 0) {
523                 dprintk("NFS: %5u commit failed with error %d.\n",
524                                 data->task.tk_pid, status);
525                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
526         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
527                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
528                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
529         }
530
531         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
532         nfs_direct_write_complete(dreq, data->inode);
533         nfs_commitdata_release(calldata);
534 }
535
536 static const struct rpc_call_ops nfs_commit_direct_ops = {
537         .rpc_call_done = nfs_direct_commit_result,
538         .rpc_release = nfs_direct_commit_release,
539 };
540
541 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
542 {
543         struct nfs_write_data *data = dreq->commit_data;
544         struct rpc_task *task;
545         struct rpc_message msg = {
546                 .rpc_argp = &data->args,
547                 .rpc_resp = &data->res,
548                 .rpc_cred = dreq->ctx->cred,
549         };
550         struct rpc_task_setup task_setup_data = {
551                 .task = &data->task,
552                 .rpc_client = NFS_CLIENT(dreq->inode),
553                 .rpc_message = &msg,
554                 .callback_ops = &nfs_commit_direct_ops,
555                 .callback_data = data,
556                 .workqueue = nfsiod_workqueue,
557                 .flags = RPC_TASK_ASYNC,
558         };
559
560         data->inode = dreq->inode;
561         data->cred = msg.rpc_cred;
562
563         data->args.fh = NFS_FH(data->inode);
564         data->args.offset = 0;
565         data->args.count = 0;
566         data->args.context = get_nfs_open_context(dreq->ctx);
567         data->res.count = 0;
568         data->res.fattr = &data->fattr;
569         data->res.verf = &data->verf;
570
571         NFS_PROTO(data->inode)->commit_setup(data, &msg);
572
573         /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
574         dreq->commit_data = NULL;
575
576         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
577
578         task = rpc_run_task(&task_setup_data);
579         if (!IS_ERR(task))
580                 rpc_put_task(task);
581 }
582
583 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
584 {
585         int flags = dreq->flags;
586
587         dreq->flags = 0;
588         switch (flags) {
589                 case NFS_ODIRECT_DO_COMMIT:
590                         nfs_direct_commit_schedule(dreq);
591                         break;
592                 case NFS_ODIRECT_RESCHED_WRITES:
593                         nfs_direct_write_reschedule(dreq);
594                         break;
595                 default:
596                         if (dreq->commit_data != NULL)
597                                 nfs_commit_free(dreq->commit_data);
598                         nfs_direct_free_writedata(dreq);
599                         nfs_zap_mapping(inode, inode->i_mapping);
600                         nfs_direct_complete(dreq);
601         }
602 }
603
604 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
605 {
606         dreq->commit_data = nfs_commitdata_alloc();
607         if (dreq->commit_data != NULL)
608                 dreq->commit_data->req = (struct nfs_page *) dreq;
609 }
610 #else
611 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
612 {
613         dreq->commit_data = NULL;
614 }
615
616 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
617 {
618         nfs_direct_free_writedata(dreq);
619         nfs_zap_mapping(inode, inode->i_mapping);
620         nfs_direct_complete(dreq);
621 }
622 #endif
623
624 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
625 {
626         struct nfs_write_data *data = calldata;
627
628         if (nfs_writeback_done(task, data) != 0)
629                 return;
630 }
631
632 /*
633  * NB: Return the value of the first error return code.  Subsequent
634  *     errors after the first one are ignored.
635  */
636 static void nfs_direct_write_release(void *calldata)
637 {
638         struct nfs_write_data *data = calldata;
639         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
640         int status = data->task.tk_status;
641
642         spin_lock(&dreq->lock);
643
644         if (unlikely(status < 0)) {
645                 /* An error has occurred, so we should not commit */
646                 dreq->flags = 0;
647                 dreq->error = status;
648         }
649         if (unlikely(dreq->error != 0))
650                 goto out_unlock;
651
652         dreq->count += data->res.count;
653
654         if (data->res.verf->committed != NFS_FILE_SYNC) {
655                 switch (dreq->flags) {
656                         case 0:
657                                 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
658                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
659                                 break;
660                         case NFS_ODIRECT_DO_COMMIT:
661                                 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
662                                         dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
663                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
664                                 }
665                 }
666         }
667 out_unlock:
668         spin_unlock(&dreq->lock);
669
670         if (put_dreq(dreq))
671                 nfs_direct_write_complete(dreq, data->inode);
672 }
673
674 static const struct rpc_call_ops nfs_write_direct_ops = {
675         .rpc_call_done = nfs_direct_write_result,
676         .rpc_release = nfs_direct_write_release,
677 };
678
679 /*
680  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
681  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
682  * bail and stop sending more writes.  Write length accounting is
683  * handled automatically by nfs_direct_write_result().  Otherwise, if
684  * no requests have been sent, just return an error.
685  */
686 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
687                                                  const struct iovec *iov,
688                                                  loff_t pos, int sync)
689 {
690         struct nfs_open_context *ctx = dreq->ctx;
691         struct inode *inode = ctx->path.dentry->d_inode;
692         unsigned long user_addr = (unsigned long)iov->iov_base;
693         size_t count = iov->iov_len;
694         struct rpc_task *task;
695         struct rpc_message msg = {
696                 .rpc_cred = ctx->cred,
697         };
698         struct rpc_task_setup task_setup_data = {
699                 .rpc_client = NFS_CLIENT(inode),
700                 .rpc_message = &msg,
701                 .callback_ops = &nfs_write_direct_ops,
702                 .workqueue = nfsiod_workqueue,
703                 .flags = RPC_TASK_ASYNC,
704         };
705         size_t wsize = NFS_SERVER(inode)->wsize;
706         unsigned int pgbase;
707         int result;
708         ssize_t started = 0;
709
710         do {
711                 struct nfs_write_data *data;
712                 size_t bytes;
713
714                 pgbase = user_addr & ~PAGE_MASK;
715                 bytes = min(wsize,count);
716
717                 result = -ENOMEM;
718                 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
719                 if (unlikely(!data))
720                         break;
721
722                 down_read(&current->mm->mmap_sem);
723                 result = get_user_pages(current, current->mm, user_addr,
724                                         data->npages, 0, 0, data->pagevec, NULL);
725                 up_read(&current->mm->mmap_sem);
726                 if (result < 0) {
727                         nfs_writedata_release(data);
728                         break;
729                 }
730                 if ((unsigned)result < data->npages) {
731                         bytes = result * PAGE_SIZE;
732                         if (bytes <= pgbase) {
733                                 nfs_direct_release_pages(data->pagevec, result);
734                                 nfs_writedata_release(data);
735                                 break;
736                         }
737                         bytes -= pgbase;
738                         data->npages = result;
739                 }
740
741                 get_dreq(dreq);
742
743                 list_move_tail(&data->pages, &dreq->rewrite_list);
744
745                 data->req = (struct nfs_page *) dreq;
746                 data->inode = inode;
747                 data->cred = msg.rpc_cred;
748                 data->args.fh = NFS_FH(inode);
749                 data->args.context = get_nfs_open_context(ctx);
750                 data->args.offset = pos;
751                 data->args.pgbase = pgbase;
752                 data->args.pages = data->pagevec;
753                 data->args.count = bytes;
754                 data->args.stable = sync;
755                 data->res.fattr = &data->fattr;
756                 data->res.count = bytes;
757                 data->res.verf = &data->verf;
758
759                 task_setup_data.task = &data->task;
760                 task_setup_data.callback_data = data;
761                 msg.rpc_argp = &data->args;
762                 msg.rpc_resp = &data->res;
763                 NFS_PROTO(inode)->write_setup(data, &msg);
764
765                 task = rpc_run_task(&task_setup_data);
766                 if (!IS_ERR(task))
767                         rpc_put_task(task);
768
769                 dprintk("NFS: %5u initiated direct write call "
770                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
771                                 data->task.tk_pid,
772                                 inode->i_sb->s_id,
773                                 (long long)NFS_FILEID(inode),
774                                 bytes,
775                                 (unsigned long long)data->args.offset);
776
777                 started += bytes;
778                 user_addr += bytes;
779                 pos += bytes;
780
781                 /* FIXME: Remove this useless math from the final patch */
782                 pgbase += bytes;
783                 pgbase &= ~PAGE_MASK;
784                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
785
786                 count -= bytes;
787         } while (count != 0);
788
789         if (started)
790                 return started;
791         return result < 0 ? (ssize_t) result : -EFAULT;
792 }
793
794 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
795                                                const struct iovec *iov,
796                                                unsigned long nr_segs,
797                                                loff_t pos, int sync)
798 {
799         ssize_t result = 0;
800         size_t requested_bytes = 0;
801         unsigned long seg;
802
803         get_dreq(dreq);
804
805         for (seg = 0; seg < nr_segs; seg++) {
806                 const struct iovec *vec = &iov[seg];
807                 result = nfs_direct_write_schedule_segment(dreq, vec,
808                                                            pos, sync);
809                 if (result < 0)
810                         break;
811                 requested_bytes += result;
812                 if ((size_t)result < vec->iov_len)
813                         break;
814                 pos += vec->iov_len;
815         }
816
817         if (put_dreq(dreq))
818                 nfs_direct_write_complete(dreq, dreq->inode);
819
820         if (requested_bytes != 0)
821                 return 0;
822
823         if (result < 0)
824                 return result;
825         return -EIO;
826 }
827
828 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
829                                 unsigned long nr_segs, loff_t pos,
830                                 size_t count)
831 {
832         ssize_t result = 0;
833         struct inode *inode = iocb->ki_filp->f_mapping->host;
834         struct nfs_direct_req *dreq;
835         size_t wsize = NFS_SERVER(inode)->wsize;
836         int sync = NFS_UNSTABLE;
837
838         dreq = nfs_direct_req_alloc();
839         if (!dreq)
840                 return -ENOMEM;
841         nfs_alloc_commit_data(dreq);
842
843         if (dreq->commit_data == NULL || count < wsize)
844                 sync = NFS_FILE_SYNC;
845
846         dreq->inode = inode;
847         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
848         if (!is_sync_kiocb(iocb))
849                 dreq->iocb = iocb;
850
851         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
852         if (!result)
853                 result = nfs_direct_wait(dreq);
854         nfs_direct_req_release(dreq);
855
856         return result;
857 }
858
859 /**
860  * nfs_file_direct_read - file direct read operation for NFS files
861  * @iocb: target I/O control block
862  * @iov: vector of user buffers into which to read data
863  * @nr_segs: size of iov vector
864  * @pos: byte offset in file where reading starts
865  *
866  * We use this function for direct reads instead of calling
867  * generic_file_aio_read() in order to avoid gfar's check to see if
868  * the request starts before the end of the file.  For that check
869  * to work, we must generate a GETATTR before each direct read, and
870  * even then there is a window between the GETATTR and the subsequent
871  * READ where the file size could change.  Our preference is simply
872  * to do all reads the application wants, and the server will take
873  * care of managing the end of file boundary.
874  *
875  * This function also eliminates unnecessarily updating the file's
876  * atime locally, as the NFS server sets the file's atime, and this
877  * client must read the updated atime from the server back into its
878  * cache.
879  */
880 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
881                                 unsigned long nr_segs, loff_t pos)
882 {
883         ssize_t retval = -EINVAL;
884         struct file *file = iocb->ki_filp;
885         struct address_space *mapping = file->f_mapping;
886         size_t count;
887
888         count = iov_length(iov, nr_segs);
889         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
890
891         dprintk("nfs: direct read(%s/%s, %zd@%Ld)\n",
892                 file->f_path.dentry->d_parent->d_name.name,
893                 file->f_path.dentry->d_name.name,
894                 count, (long long) pos);
895
896         retval = 0;
897         if (!count)
898                 goto out;
899
900         retval = nfs_sync_mapping(mapping);
901         if (retval)
902                 goto out;
903
904         retval = nfs_direct_read(iocb, iov, nr_segs, pos);
905         if (retval > 0)
906                 iocb->ki_pos = pos + retval;
907
908 out:
909         return retval;
910 }
911
912 /**
913  * nfs_file_direct_write - file direct write operation for NFS files
914  * @iocb: target I/O control block
915  * @iov: vector of user buffers from which to write data
916  * @nr_segs: size of iov vector
917  * @pos: byte offset in file where writing starts
918  *
919  * We use this function for direct writes instead of calling
920  * generic_file_aio_write() in order to avoid taking the inode
921  * semaphore and updating the i_size.  The NFS server will set
922  * the new i_size and this client must read the updated size
923  * back into its cache.  We let the server do generic write
924  * parameter checking and report problems.
925  *
926  * We also avoid an unnecessary invocation of generic_osync_inode(),
927  * as it is fairly meaningless to sync the metadata of an NFS file.
928  *
929  * We eliminate local atime updates, see direct read above.
930  *
931  * We avoid unnecessary page cache invalidations for normal cached
932  * readers of this file.
933  *
934  * Note that O_APPEND is not supported for NFS direct writes, as there
935  * is no atomic O_APPEND write facility in the NFS protocol.
936  */
937 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
938                                 unsigned long nr_segs, loff_t pos)
939 {
940         ssize_t retval = -EINVAL;
941         struct file *file = iocb->ki_filp;
942         struct address_space *mapping = file->f_mapping;
943         size_t count;
944
945         count = iov_length(iov, nr_segs);
946         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
947
948         dfprintk(VFS, "nfs: direct write(%s/%s, %zd@%Ld)\n",
949                 file->f_path.dentry->d_parent->d_name.name,
950                 file->f_path.dentry->d_name.name,
951                 count, (long long) pos);
952
953         retval = generic_write_checks(file, &pos, &count, 0);
954         if (retval)
955                 goto out;
956
957         retval = -EINVAL;
958         if ((ssize_t) count < 0)
959                 goto out;
960         retval = 0;
961         if (!count)
962                 goto out;
963
964         retval = nfs_sync_mapping(mapping);
965         if (retval)
966                 goto out;
967
968         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
969
970         if (retval > 0)
971                 iocb->ki_pos = pos + retval;
972
973 out:
974         return retval;
975 }
976
977 /**
978  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
979  *
980  */
981 int __init nfs_init_directcache(void)
982 {
983         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
984                                                 sizeof(struct nfs_direct_req),
985                                                 0, (SLAB_RECLAIM_ACCOUNT|
986                                                         SLAB_MEM_SPREAD),
987                                                 NULL);
988         if (nfs_direct_cachep == NULL)
989                 return -ENOMEM;
990
991         return 0;
992 }
993
994 /**
995  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
996  *
997  */
998 void nfs_destroy_directcache(void)
999 {
1000         kmem_cache_destroy(nfs_direct_cachep);
1001 }