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Linux/fs/nfs/pagelist.c

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  1 /*
  2  * linux/fs/nfs/pagelist.c
  3  *
  4  * A set of helper functions for managing NFS read and write requests.
  5  * The main purpose of these routines is to provide support for the
  6  * coalescing of several requests into a single RPC call.
  7  *
  8  * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
  9  *
 10  */
 11 
 12 #include <linux/slab.h>
 13 #include <linux/file.h>
 14 #include <linux/sched.h>
 15 #include <linux/sunrpc/clnt.h>
 16 #include <linux/nfs.h>
 17 #include <linux/nfs3.h>
 18 #include <linux/nfs4.h>
 19 #include <linux/nfs_page.h>
 20 #include <linux/nfs_fs.h>
 21 #include <linux/nfs_mount.h>
 22 #include <linux/export.h>
 23 
 24 #include "internal.h"
 25 #include "pnfs.h"
 26 
 27 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
 28 
 29 static struct kmem_cache *nfs_page_cachep;
 30 static const struct rpc_call_ops nfs_pgio_common_ops;
 31 
 32 struct nfs_pgio_mirror *
 33 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
 34 {
 35         return nfs_pgio_has_mirroring(desc) ?
 36                 &desc->pg_mirrors[desc->pg_mirror_idx] :
 37                 &desc->pg_mirrors[0];
 38 }
 39 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
 40 
 41 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
 42                        struct nfs_pgio_header *hdr,
 43                        void (*release)(struct nfs_pgio_header *hdr))
 44 {
 45         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 46 
 47 
 48         hdr->req = nfs_list_entry(mirror->pg_list.next);
 49         hdr->inode = desc->pg_inode;
 50         hdr->cred = hdr->req->wb_context->cred;
 51         hdr->io_start = req_offset(hdr->req);
 52         hdr->good_bytes = mirror->pg_count;
 53         hdr->io_completion = desc->pg_io_completion;
 54         hdr->dreq = desc->pg_dreq;
 55         hdr->release = release;
 56         hdr->completion_ops = desc->pg_completion_ops;
 57         if (hdr->completion_ops->init_hdr)
 58                 hdr->completion_ops->init_hdr(hdr);
 59 
 60         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
 61 }
 62 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
 63 
 64 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
 65 {
 66         spin_lock(&hdr->lock);
 67         if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags)
 68             || pos < hdr->io_start + hdr->good_bytes) {
 69                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
 70                 hdr->good_bytes = pos - hdr->io_start;
 71                 hdr->error = error;
 72         }
 73         spin_unlock(&hdr->lock);
 74 }
 75 
 76 static inline struct nfs_page *
 77 nfs_page_alloc(void)
 78 {
 79         struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
 80         if (p)
 81                 INIT_LIST_HEAD(&p->wb_list);
 82         return p;
 83 }
 84 
 85 static inline void
 86 nfs_page_free(struct nfs_page *p)
 87 {
 88         kmem_cache_free(nfs_page_cachep, p);
 89 }
 90 
 91 /**
 92  * nfs_iocounter_wait - wait for i/o to complete
 93  * @l_ctx: nfs_lock_context with io_counter to use
 94  *
 95  * returns -ERESTARTSYS if interrupted by a fatal signal.
 96  * Otherwise returns 0 once the io_count hits 0.
 97  */
 98 int
 99 nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
100 {
101         return wait_var_event_killable(&l_ctx->io_count,
102                                        !atomic_read(&l_ctx->io_count));
103 }
104 
105 /**
106  * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
107  * to complete
108  * @task: the rpc_task that should wait
109  * @l_ctx: nfs_lock_context with io_counter to check
110  *
111  * Returns true if there is outstanding I/O to wait on and the
112  * task has been put to sleep.
113  */
114 bool
115 nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
116 {
117         struct inode *inode = d_inode(l_ctx->open_context->dentry);
118         bool ret = false;
119 
120         if (atomic_read(&l_ctx->io_count) > 0) {
121                 rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
122                 ret = true;
123         }
124 
125         if (atomic_read(&l_ctx->io_count) == 0) {
126                 rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
127                 ret = false;
128         }
129 
130         return ret;
131 }
132 EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
133 
134 /*
135  * nfs_page_group_lock - lock the head of the page group
136  * @req - request in group that is to be locked
137  *
138  * this lock must be held when traversing or modifying the page
139  * group list
140  *
141  * return 0 on success, < 0 on error
142  */
143 int
144 nfs_page_group_lock(struct nfs_page *req)
145 {
146         struct nfs_page *head = req->wb_head;
147 
148         WARN_ON_ONCE(head != head->wb_head);
149 
150         if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
151                 return 0;
152 
153         set_bit(PG_CONTENDED1, &head->wb_flags);
154         smp_mb__after_atomic();
155         return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
156                                 TASK_UNINTERRUPTIBLE);
157 }
158 
159 /*
160  * nfs_page_group_unlock - unlock the head of the page group
161  * @req - request in group that is to be unlocked
162  */
163 void
164 nfs_page_group_unlock(struct nfs_page *req)
165 {
166         struct nfs_page *head = req->wb_head;
167 
168         WARN_ON_ONCE(head != head->wb_head);
169 
170         smp_mb__before_atomic();
171         clear_bit(PG_HEADLOCK, &head->wb_flags);
172         smp_mb__after_atomic();
173         if (!test_bit(PG_CONTENDED1, &head->wb_flags))
174                 return;
175         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
176 }
177 
178 /*
179  * nfs_page_group_sync_on_bit_locked
180  *
181  * must be called with page group lock held
182  */
183 static bool
184 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
185 {
186         struct nfs_page *head = req->wb_head;
187         struct nfs_page *tmp;
188 
189         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
190         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
191 
192         tmp = req->wb_this_page;
193         while (tmp != req) {
194                 if (!test_bit(bit, &tmp->wb_flags))
195                         return false;
196                 tmp = tmp->wb_this_page;
197         }
198 
199         /* true! reset all bits */
200         tmp = req;
201         do {
202                 clear_bit(bit, &tmp->wb_flags);
203                 tmp = tmp->wb_this_page;
204         } while (tmp != req);
205 
206         return true;
207 }
208 
209 /*
210  * nfs_page_group_sync_on_bit - set bit on current request, but only
211  *   return true if the bit is set for all requests in page group
212  * @req - request in page group
213  * @bit - PG_* bit that is used to sync page group
214  */
215 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
216 {
217         bool ret;
218 
219         nfs_page_group_lock(req);
220         ret = nfs_page_group_sync_on_bit_locked(req, bit);
221         nfs_page_group_unlock(req);
222 
223         return ret;
224 }
225 
226 /*
227  * nfs_page_group_init - Initialize the page group linkage for @req
228  * @req - a new nfs request
229  * @prev - the previous request in page group, or NULL if @req is the first
230  *         or only request in the group (the head).
231  */
232 static inline void
233 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
234 {
235         struct inode *inode;
236         WARN_ON_ONCE(prev == req);
237 
238         if (!prev) {
239                 /* a head request */
240                 req->wb_head = req;
241                 req->wb_this_page = req;
242         } else {
243                 /* a subrequest */
244                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
245                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
246                 req->wb_head = prev->wb_head;
247                 req->wb_this_page = prev->wb_this_page;
248                 prev->wb_this_page = req;
249 
250                 /* All subrequests take a ref on the head request until
251                  * nfs_page_group_destroy is called */
252                 kref_get(&req->wb_head->wb_kref);
253 
254                 /* grab extra ref and bump the request count if head request
255                  * has extra ref from the write/commit path to handle handoff
256                  * between write and commit lists. */
257                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
258                         inode = page_file_mapping(req->wb_page)->host;
259                         set_bit(PG_INODE_REF, &req->wb_flags);
260                         kref_get(&req->wb_kref);
261                         atomic_long_inc(&NFS_I(inode)->nrequests);
262                 }
263         }
264 }
265 
266 /*
267  * nfs_page_group_destroy - sync the destruction of page groups
268  * @req - request that no longer needs the page group
269  *
270  * releases the page group reference from each member once all
271  * members have called this function.
272  */
273 static void
274 nfs_page_group_destroy(struct kref *kref)
275 {
276         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
277         struct nfs_page *head = req->wb_head;
278         struct nfs_page *tmp, *next;
279 
280         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
281                 goto out;
282 
283         tmp = req;
284         do {
285                 next = tmp->wb_this_page;
286                 /* unlink and free */
287                 tmp->wb_this_page = tmp;
288                 tmp->wb_head = tmp;
289                 nfs_free_request(tmp);
290                 tmp = next;
291         } while (tmp != req);
292 out:
293         /* subrequests must release the ref on the head request */
294         if (head != req)
295                 nfs_release_request(head);
296 }
297 
298 /**
299  * nfs_create_request - Create an NFS read/write request.
300  * @ctx: open context to use
301  * @page: page to write
302  * @last: last nfs request created for this page group or NULL if head
303  * @offset: starting offset within the page for the write
304  * @count: number of bytes to read/write
305  *
306  * The page must be locked by the caller. This makes sure we never
307  * create two different requests for the same page.
308  * User should ensure it is safe to sleep in this function.
309  */
310 struct nfs_page *
311 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
312                    struct nfs_page *last, unsigned int offset,
313                    unsigned int count)
314 {
315         struct nfs_page         *req;
316         struct nfs_lock_context *l_ctx;
317 
318         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
319                 return ERR_PTR(-EBADF);
320         /* try to allocate the request struct */
321         req = nfs_page_alloc();
322         if (req == NULL)
323                 return ERR_PTR(-ENOMEM);
324 
325         /* get lock context early so we can deal with alloc failures */
326         l_ctx = nfs_get_lock_context(ctx);
327         if (IS_ERR(l_ctx)) {
328                 nfs_page_free(req);
329                 return ERR_CAST(l_ctx);
330         }
331         req->wb_lock_context = l_ctx;
332         atomic_inc(&l_ctx->io_count);
333 
334         /* Initialize the request struct. Initially, we assume a
335          * long write-back delay. This will be adjusted in
336          * update_nfs_request below if the region is not locked. */
337         req->wb_page    = page;
338         if (page) {
339                 req->wb_index = page_index(page);
340                 get_page(page);
341         }
342         req->wb_offset  = offset;
343         req->wb_pgbase  = offset;
344         req->wb_bytes   = count;
345         req->wb_context = get_nfs_open_context(ctx);
346         kref_init(&req->wb_kref);
347         nfs_page_group_init(req, last);
348         return req;
349 }
350 
351 /**
352  * nfs_unlock_request - Unlock request and wake up sleepers.
353  * @req:
354  */
355 void nfs_unlock_request(struct nfs_page *req)
356 {
357         if (!NFS_WBACK_BUSY(req)) {
358                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
359                 BUG();
360         }
361         smp_mb__before_atomic();
362         clear_bit(PG_BUSY, &req->wb_flags);
363         smp_mb__after_atomic();
364         if (!test_bit(PG_CONTENDED2, &req->wb_flags))
365                 return;
366         wake_up_bit(&req->wb_flags, PG_BUSY);
367 }
368 
369 /**
370  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
371  * @req:
372  */
373 void nfs_unlock_and_release_request(struct nfs_page *req)
374 {
375         nfs_unlock_request(req);
376         nfs_release_request(req);
377 }
378 
379 /*
380  * nfs_clear_request - Free up all resources allocated to the request
381  * @req:
382  *
383  * Release page and open context resources associated with a read/write
384  * request after it has completed.
385  */
386 static void nfs_clear_request(struct nfs_page *req)
387 {
388         struct page *page = req->wb_page;
389         struct nfs_open_context *ctx = req->wb_context;
390         struct nfs_lock_context *l_ctx = req->wb_lock_context;
391 
392         if (page != NULL) {
393                 put_page(page);
394                 req->wb_page = NULL;
395         }
396         if (l_ctx != NULL) {
397                 if (atomic_dec_and_test(&l_ctx->io_count)) {
398                         wake_up_var(&l_ctx->io_count);
399                         if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
400                                 rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
401                 }
402                 nfs_put_lock_context(l_ctx);
403                 req->wb_lock_context = NULL;
404         }
405         if (ctx != NULL) {
406                 put_nfs_open_context(ctx);
407                 req->wb_context = NULL;
408         }
409 }
410 
411 /**
412  * nfs_release_request - Release the count on an NFS read/write request
413  * @req: request to release
414  *
415  * Note: Should never be called with the spinlock held!
416  */
417 void nfs_free_request(struct nfs_page *req)
418 {
419         WARN_ON_ONCE(req->wb_this_page != req);
420 
421         /* extra debug: make sure no sync bits are still set */
422         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
423         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
424         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
425         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
426         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
427 
428         /* Release struct file and open context */
429         nfs_clear_request(req);
430         nfs_page_free(req);
431 }
432 
433 void nfs_release_request(struct nfs_page *req)
434 {
435         kref_put(&req->wb_kref, nfs_page_group_destroy);
436 }
437 EXPORT_SYMBOL_GPL(nfs_release_request);
438 
439 /**
440  * nfs_wait_on_request - Wait for a request to complete.
441  * @req: request to wait upon.
442  *
443  * Interruptible by fatal signals only.
444  * The user is responsible for holding a count on the request.
445  */
446 int
447 nfs_wait_on_request(struct nfs_page *req)
448 {
449         if (!test_bit(PG_BUSY, &req->wb_flags))
450                 return 0;
451         set_bit(PG_CONTENDED2, &req->wb_flags);
452         smp_mb__after_atomic();
453         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
454                               TASK_UNINTERRUPTIBLE);
455 }
456 EXPORT_SYMBOL_GPL(nfs_wait_on_request);
457 
458 /*
459  * nfs_generic_pg_test - determine if requests can be coalesced
460  * @desc: pointer to descriptor
461  * @prev: previous request in desc, or NULL
462  * @req: this request
463  *
464  * Returns zero if @req can be coalesced into @desc, otherwise it returns
465  * the size of the request.
466  */
467 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
468                            struct nfs_page *prev, struct nfs_page *req)
469 {
470         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
471 
472 
473         if (mirror->pg_count > mirror->pg_bsize) {
474                 /* should never happen */
475                 WARN_ON_ONCE(1);
476                 return 0;
477         }
478 
479         /*
480          * Limit the request size so that we can still allocate a page array
481          * for it without upsetting the slab allocator.
482          */
483         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
484                         sizeof(struct page *) > PAGE_SIZE)
485                 return 0;
486 
487         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
488 }
489 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
490 
491 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
492 {
493         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
494 
495         if (hdr) {
496                 INIT_LIST_HEAD(&hdr->pages);
497                 spin_lock_init(&hdr->lock);
498                 hdr->rw_ops = ops;
499         }
500         return hdr;
501 }
502 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
503 
504 /**
505  * nfs_pgio_data_destroy - make @hdr suitable for reuse
506  *
507  * Frees memory and releases refs from nfs_generic_pgio, so that it may
508  * be called again.
509  *
510  * @hdr: A header that has had nfs_generic_pgio called
511  */
512 static void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
513 {
514         if (hdr->args.context)
515                 put_nfs_open_context(hdr->args.context);
516         if (hdr->page_array.pagevec != hdr->page_array.page_array)
517                 kfree(hdr->page_array.pagevec);
518 }
519 
520 /*
521  * nfs_pgio_header_free - Free a read or write header
522  * @hdr: The header to free
523  */
524 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
525 {
526         nfs_pgio_data_destroy(hdr);
527         hdr->rw_ops->rw_free_header(hdr);
528 }
529 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
530 
531 /**
532  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
533  * @hdr: The pageio hdr
534  * @count: Number of bytes to read
535  * @offset: Initial offset
536  * @how: How to commit data (writes only)
537  * @cinfo: Commit information for the call (writes only)
538  */
539 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
540                               unsigned int count,
541                               int how, struct nfs_commit_info *cinfo)
542 {
543         struct nfs_page *req = hdr->req;
544 
545         /* Set up the RPC argument and reply structs
546          * NB: take care not to mess about with hdr->commit et al. */
547 
548         hdr->args.fh     = NFS_FH(hdr->inode);
549         hdr->args.offset = req_offset(req);
550         /* pnfs_set_layoutcommit needs this */
551         hdr->mds_offset = hdr->args.offset;
552         hdr->args.pgbase = req->wb_pgbase;
553         hdr->args.pages  = hdr->page_array.pagevec;
554         hdr->args.count  = count;
555         hdr->args.context = get_nfs_open_context(req->wb_context);
556         hdr->args.lock_context = req->wb_lock_context;
557         hdr->args.stable  = NFS_UNSTABLE;
558         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
559         case 0:
560                 break;
561         case FLUSH_COND_STABLE:
562                 if (nfs_reqs_to_commit(cinfo))
563                         break;
564                 /* fall through */
565         default:
566                 hdr->args.stable = NFS_FILE_SYNC;
567         }
568 
569         hdr->res.fattr   = &hdr->fattr;
570         hdr->res.count   = count;
571         hdr->res.eof     = 0;
572         hdr->res.verf    = &hdr->verf;
573         nfs_fattr_init(&hdr->fattr);
574 }
575 
576 /**
577  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
578  * @task: The current task
579  * @calldata: pageio header to prepare
580  */
581 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
582 {
583         struct nfs_pgio_header *hdr = calldata;
584         int err;
585         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
586         if (err)
587                 rpc_exit(task, err);
588 }
589 
590 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
591                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
592                       const struct rpc_call_ops *call_ops, int how, int flags)
593 {
594         struct rpc_task *task;
595         struct rpc_message msg = {
596                 .rpc_argp = &hdr->args,
597                 .rpc_resp = &hdr->res,
598                 .rpc_cred = cred,
599         };
600         struct rpc_task_setup task_setup_data = {
601                 .rpc_client = clnt,
602                 .task = &hdr->task,
603                 .rpc_message = &msg,
604                 .callback_ops = call_ops,
605                 .callback_data = hdr,
606                 .workqueue = nfsiod_workqueue,
607                 .flags = RPC_TASK_ASYNC | flags,
608         };
609         int ret = 0;
610 
611         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
612 
613         dprintk("NFS: initiated pgio call "
614                 "(req %s/%llu, %u bytes @ offset %llu)\n",
615                 hdr->inode->i_sb->s_id,
616                 (unsigned long long)NFS_FILEID(hdr->inode),
617                 hdr->args.count,
618                 (unsigned long long)hdr->args.offset);
619 
620         task = rpc_run_task(&task_setup_data);
621         if (IS_ERR(task)) {
622                 ret = PTR_ERR(task);
623                 goto out;
624         }
625         if (how & FLUSH_SYNC) {
626                 ret = rpc_wait_for_completion_task(task);
627                 if (ret == 0)
628                         ret = task->tk_status;
629         }
630         rpc_put_task(task);
631 out:
632         return ret;
633 }
634 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
635 
636 /**
637  * nfs_pgio_error - Clean up from a pageio error
638  * @desc: IO descriptor
639  * @hdr: pageio header
640  */
641 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
642 {
643         set_bit(NFS_IOHDR_REDO, &hdr->flags);
644         hdr->completion_ops->completion(hdr);
645 }
646 
647 /**
648  * nfs_pgio_release - Release pageio data
649  * @calldata: The pageio header to release
650  */
651 static void nfs_pgio_release(void *calldata)
652 {
653         struct nfs_pgio_header *hdr = calldata;
654         hdr->completion_ops->completion(hdr);
655 }
656 
657 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
658                                    unsigned int bsize)
659 {
660         INIT_LIST_HEAD(&mirror->pg_list);
661         mirror->pg_bytes_written = 0;
662         mirror->pg_count = 0;
663         mirror->pg_bsize = bsize;
664         mirror->pg_base = 0;
665         mirror->pg_recoalesce = 0;
666 }
667 
668 /**
669  * nfs_pageio_init - initialise a page io descriptor
670  * @desc: pointer to descriptor
671  * @inode: pointer to inode
672  * @pg_ops: pointer to pageio operations
673  * @compl_ops: pointer to pageio completion operations
674  * @rw_ops: pointer to nfs read/write operations
675  * @bsize: io block size
676  * @io_flags: extra parameters for the io function
677  */
678 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
679                      struct inode *inode,
680                      const struct nfs_pageio_ops *pg_ops,
681                      const struct nfs_pgio_completion_ops *compl_ops,
682                      const struct nfs_rw_ops *rw_ops,
683                      size_t bsize,
684                      int io_flags)
685 {
686         desc->pg_moreio = 0;
687         desc->pg_inode = inode;
688         desc->pg_ops = pg_ops;
689         desc->pg_completion_ops = compl_ops;
690         desc->pg_rw_ops = rw_ops;
691         desc->pg_ioflags = io_flags;
692         desc->pg_error = 0;
693         desc->pg_lseg = NULL;
694         desc->pg_io_completion = NULL;
695         desc->pg_dreq = NULL;
696         desc->pg_bsize = bsize;
697 
698         desc->pg_mirror_count = 1;
699         desc->pg_mirror_idx = 0;
700 
701         desc->pg_mirrors_dynamic = NULL;
702         desc->pg_mirrors = desc->pg_mirrors_static;
703         nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
704 }
705 
706 /**
707  * nfs_pgio_result - Basic pageio error handling
708  * @task: The task that ran
709  * @calldata: Pageio header to check
710  */
711 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
712 {
713         struct nfs_pgio_header *hdr = calldata;
714         struct inode *inode = hdr->inode;
715 
716         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
717                 task->tk_pid, task->tk_status);
718 
719         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
720                 return;
721         if (task->tk_status < 0)
722                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
723         else
724                 hdr->rw_ops->rw_result(task, hdr);
725 }
726 
727 /*
728  * Create an RPC task for the given read or write request and kick it.
729  * The page must have been locked by the caller.
730  *
731  * It may happen that the page we're passed is not marked dirty.
732  * This is the case if nfs_updatepage detects a conflicting request
733  * that has been written but not committed.
734  */
735 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
736                      struct nfs_pgio_header *hdr)
737 {
738         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
739 
740         struct nfs_page         *req;
741         struct page             **pages,
742                                 *last_page;
743         struct list_head *head = &mirror->pg_list;
744         struct nfs_commit_info cinfo;
745         struct nfs_page_array *pg_array = &hdr->page_array;
746         unsigned int pagecount, pageused;
747         gfp_t gfp_flags = GFP_KERNEL;
748 
749         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
750         pg_array->npages = pagecount;
751 
752         if (pagecount <= ARRAY_SIZE(pg_array->page_array))
753                 pg_array->pagevec = pg_array->page_array;
754         else {
755                 if (hdr->rw_mode == FMODE_WRITE)
756                         gfp_flags = GFP_NOIO;
757                 pg_array->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
758                 if (!pg_array->pagevec) {
759                         pg_array->npages = 0;
760                         nfs_pgio_error(hdr);
761                         desc->pg_error = -ENOMEM;
762                         return desc->pg_error;
763                 }
764         }
765 
766         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
767         pages = hdr->page_array.pagevec;
768         last_page = NULL;
769         pageused = 0;
770         while (!list_empty(head)) {
771                 req = nfs_list_entry(head->next);
772                 nfs_list_remove_request(req);
773                 nfs_list_add_request(req, &hdr->pages);
774 
775                 if (!last_page || last_page != req->wb_page) {
776                         pageused++;
777                         if (pageused > pagecount)
778                                 break;
779                         *pages++ = last_page = req->wb_page;
780                 }
781         }
782         if (WARN_ON_ONCE(pageused != pagecount)) {
783                 nfs_pgio_error(hdr);
784                 desc->pg_error = -EINVAL;
785                 return desc->pg_error;
786         }
787 
788         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
789             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
790                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
791 
792         /* Set up the argument struct */
793         nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
794         desc->pg_rpc_callops = &nfs_pgio_common_ops;
795         return 0;
796 }
797 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
798 
799 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
800 {
801         struct nfs_pgio_header *hdr;
802         int ret;
803 
804         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
805         if (!hdr) {
806                 desc->pg_error = -ENOMEM;
807                 return desc->pg_error;
808         }
809         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
810         ret = nfs_generic_pgio(desc, hdr);
811         if (ret == 0)
812                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
813                                         hdr,
814                                         hdr->cred,
815                                         NFS_PROTO(hdr->inode),
816                                         desc->pg_rpc_callops,
817                                         desc->pg_ioflags, 0);
818         return ret;
819 }
820 
821 static struct nfs_pgio_mirror *
822 nfs_pageio_alloc_mirrors(struct nfs_pageio_descriptor *desc,
823                 unsigned int mirror_count)
824 {
825         struct nfs_pgio_mirror *ret;
826         unsigned int i;
827 
828         kfree(desc->pg_mirrors_dynamic);
829         desc->pg_mirrors_dynamic = NULL;
830         if (mirror_count == 1)
831                 return desc->pg_mirrors_static;
832         ret = kmalloc_array(mirror_count, sizeof(*ret), GFP_NOFS);
833         if (ret != NULL) {
834                 for (i = 0; i < mirror_count; i++)
835                         nfs_pageio_mirror_init(&ret[i], desc->pg_bsize);
836                 desc->pg_mirrors_dynamic = ret;
837         }
838         return ret;
839 }
840 
841 /*
842  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
843  *                              by calling the pg_get_mirror_count op
844  */
845 static void nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
846                                        struct nfs_page *req)
847 {
848         unsigned int mirror_count = 1;
849 
850         if (pgio->pg_ops->pg_get_mirror_count)
851                 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
852         if (mirror_count == pgio->pg_mirror_count || pgio->pg_error < 0)
853                 return;
854 
855         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX) {
856                 pgio->pg_error = -EINVAL;
857                 return;
858         }
859 
860         pgio->pg_mirrors = nfs_pageio_alloc_mirrors(pgio, mirror_count);
861         if (pgio->pg_mirrors == NULL) {
862                 pgio->pg_error = -ENOMEM;
863                 pgio->pg_mirrors = pgio->pg_mirrors_static;
864                 mirror_count = 1;
865         }
866         pgio->pg_mirror_count = mirror_count;
867 }
868 
869 /*
870  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
871  */
872 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
873 {
874         pgio->pg_mirror_count = 1;
875         pgio->pg_mirror_idx = 0;
876 }
877 
878 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
879 {
880         pgio->pg_mirror_count = 1;
881         pgio->pg_mirror_idx = 0;
882         pgio->pg_mirrors = pgio->pg_mirrors_static;
883         kfree(pgio->pg_mirrors_dynamic);
884         pgio->pg_mirrors_dynamic = NULL;
885 }
886 
887 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
888                 const struct nfs_lock_context *l2)
889 {
890         return l1->lockowner == l2->lockowner;
891 }
892 
893 /**
894  * nfs_can_coalesce_requests - test two requests for compatibility
895  * @prev: pointer to nfs_page
896  * @req: pointer to nfs_page
897  *
898  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
899  * page data area they describe is contiguous, and that their RPC
900  * credentials, NFSv4 open state, and lockowners are the same.
901  *
902  * Return 'true' if this is the case, else return 'false'.
903  */
904 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
905                                       struct nfs_page *req,
906                                       struct nfs_pageio_descriptor *pgio)
907 {
908         size_t size;
909         struct file_lock_context *flctx;
910 
911         if (prev) {
912                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
913                         return false;
914                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
915                 if (flctx != NULL &&
916                     !(list_empty_careful(&flctx->flc_posix) &&
917                       list_empty_careful(&flctx->flc_flock)) &&
918                     !nfs_match_lock_context(req->wb_lock_context,
919                                             prev->wb_lock_context))
920                         return false;
921                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
922                         return false;
923                 if (req->wb_page == prev->wb_page) {
924                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
925                                 return false;
926                 } else {
927                         if (req->wb_pgbase != 0 ||
928                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
929                                 return false;
930                 }
931         }
932         size = pgio->pg_ops->pg_test(pgio, prev, req);
933         WARN_ON_ONCE(size > req->wb_bytes);
934         if (size && size < req->wb_bytes)
935                 req->wb_bytes = size;
936         return size > 0;
937 }
938 
939 /**
940  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
941  * @desc: destination io descriptor
942  * @req: request
943  *
944  * Returns true if the request 'req' was successfully coalesced into the
945  * existing list of pages 'desc'.
946  */
947 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
948                                      struct nfs_page *req)
949 {
950         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
951 
952         struct nfs_page *prev = NULL;
953 
954         if (mirror->pg_count != 0) {
955                 prev = nfs_list_entry(mirror->pg_list.prev);
956         } else {
957                 if (desc->pg_ops->pg_init)
958                         desc->pg_ops->pg_init(desc, req);
959                 if (desc->pg_error < 0)
960                         return 0;
961                 mirror->pg_base = req->wb_pgbase;
962         }
963         if (!nfs_can_coalesce_requests(prev, req, desc))
964                 return 0;
965         nfs_list_remove_request(req);
966         nfs_list_add_request(req, &mirror->pg_list);
967         mirror->pg_count += req->wb_bytes;
968         return 1;
969 }
970 
971 /*
972  * Helper for nfs_pageio_add_request and nfs_pageio_complete
973  */
974 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
975 {
976         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
977 
978 
979         if (!list_empty(&mirror->pg_list)) {
980                 int error = desc->pg_ops->pg_doio(desc);
981                 if (error < 0)
982                         desc->pg_error = error;
983                 else
984                         mirror->pg_bytes_written += mirror->pg_count;
985         }
986         if (list_empty(&mirror->pg_list)) {
987                 mirror->pg_count = 0;
988                 mirror->pg_base = 0;
989         }
990 }
991 
992 /**
993  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
994  * @desc: destination io descriptor
995  * @req: request
996  *
997  * This may split a request into subrequests which are all part of the
998  * same page group.
999  *
1000  * Returns true if the request 'req' was successfully coalesced into the
1001  * existing list of pages 'desc'.
1002  */
1003 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1004                            struct nfs_page *req)
1005 {
1006         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1007 
1008         struct nfs_page *subreq;
1009         unsigned int bytes_left = 0;
1010         unsigned int offset, pgbase;
1011 
1012         nfs_page_group_lock(req);
1013 
1014         subreq = req;
1015         bytes_left = subreq->wb_bytes;
1016         offset = subreq->wb_offset;
1017         pgbase = subreq->wb_pgbase;
1018 
1019         do {
1020                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1021                         /* make sure pg_test call(s) did nothing */
1022                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1023                         WARN_ON_ONCE(subreq->wb_offset != offset);
1024                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1025 
1026                         nfs_page_group_unlock(req);
1027                         desc->pg_moreio = 1;
1028                         nfs_pageio_doio(desc);
1029                         if (desc->pg_error < 0)
1030                                 return 0;
1031                         if (mirror->pg_recoalesce)
1032                                 return 0;
1033                         /* retry add_request for this subreq */
1034                         nfs_page_group_lock(req);
1035                         continue;
1036                 }
1037 
1038                 /* check for buggy pg_test call(s) */
1039                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1040                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1041                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1042 
1043                 bytes_left -= subreq->wb_bytes;
1044                 offset += subreq->wb_bytes;
1045                 pgbase += subreq->wb_bytes;
1046 
1047                 if (bytes_left) {
1048                         subreq = nfs_create_request(req->wb_context,
1049                                         req->wb_page,
1050                                         subreq, pgbase, bytes_left);
1051                         if (IS_ERR(subreq))
1052                                 goto err_ptr;
1053                         nfs_lock_request(subreq);
1054                         subreq->wb_offset  = offset;
1055                         subreq->wb_index = req->wb_index;
1056                 }
1057         } while (bytes_left > 0);
1058 
1059         nfs_page_group_unlock(req);
1060         return 1;
1061 err_ptr:
1062         desc->pg_error = PTR_ERR(subreq);
1063         nfs_page_group_unlock(req);
1064         return 0;
1065 }
1066 
1067 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1068 {
1069         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1070         LIST_HEAD(head);
1071 
1072         do {
1073                 list_splice_init(&mirror->pg_list, &head);
1074                 mirror->pg_bytes_written -= mirror->pg_count;
1075                 mirror->pg_count = 0;
1076                 mirror->pg_base = 0;
1077                 mirror->pg_recoalesce = 0;
1078 
1079                 while (!list_empty(&head)) {
1080                         struct nfs_page *req;
1081 
1082                         req = list_first_entry(&head, struct nfs_page, wb_list);
1083                         nfs_list_remove_request(req);
1084                         if (__nfs_pageio_add_request(desc, req))
1085                                 continue;
1086                         if (desc->pg_error < 0) {
1087                                 list_splice_tail(&head, &mirror->pg_list);
1088                                 mirror->pg_recoalesce = 1;
1089                                 return 0;
1090                         }
1091                         break;
1092                 }
1093         } while (mirror->pg_recoalesce);
1094         return 1;
1095 }
1096 
1097 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1098                 struct nfs_page *req)
1099 {
1100         int ret;
1101 
1102         do {
1103                 ret = __nfs_pageio_add_request(desc, req);
1104                 if (ret)
1105                         break;
1106                 if (desc->pg_error < 0)
1107                         break;
1108                 ret = nfs_do_recoalesce(desc);
1109         } while (ret);
1110 
1111         return ret;
1112 }
1113 
1114 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1115                            struct nfs_page *req)
1116 {
1117         u32 midx;
1118         unsigned int pgbase, offset, bytes;
1119         struct nfs_page *dupreq, *lastreq;
1120 
1121         pgbase = req->wb_pgbase;
1122         offset = req->wb_offset;
1123         bytes = req->wb_bytes;
1124 
1125         nfs_pageio_setup_mirroring(desc, req);
1126         if (desc->pg_error < 0)
1127                 goto out_failed;
1128 
1129         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1130                 if (midx) {
1131                         nfs_page_group_lock(req);
1132 
1133                         /* find the last request */
1134                         for (lastreq = req->wb_head;
1135                              lastreq->wb_this_page != req->wb_head;
1136                              lastreq = lastreq->wb_this_page)
1137                                 ;
1138 
1139                         dupreq = nfs_create_request(req->wb_context,
1140                                         req->wb_page, lastreq, pgbase, bytes);
1141 
1142                         if (IS_ERR(dupreq)) {
1143                                 nfs_page_group_unlock(req);
1144                                 desc->pg_error = PTR_ERR(dupreq);
1145                                 goto out_failed;
1146                         }
1147 
1148                         nfs_lock_request(dupreq);
1149                         nfs_page_group_unlock(req);
1150                         dupreq->wb_offset = offset;
1151                         dupreq->wb_index = req->wb_index;
1152                 } else
1153                         dupreq = req;
1154 
1155                 if (nfs_pgio_has_mirroring(desc))
1156                         desc->pg_mirror_idx = midx;
1157                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1158                         goto out_failed;
1159         }
1160 
1161         return 1;
1162 
1163 out_failed:
1164         /*
1165          * We might have failed before sending any reqs over wire.
1166          * Clean up rest of the reqs in mirror pg_list.
1167          */
1168         if (desc->pg_error) {
1169                 struct nfs_pgio_mirror *mirror;
1170                 void (*func)(struct list_head *);
1171 
1172                 /* remember fatal errors */
1173                 if (nfs_error_is_fatal(desc->pg_error))
1174                         nfs_context_set_write_error(req->wb_context,
1175                                                     desc->pg_error);
1176 
1177                 func = desc->pg_completion_ops->error_cleanup;
1178                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1179                         mirror = &desc->pg_mirrors[midx];
1180                         func(&mirror->pg_list);
1181                 }
1182         }
1183         return 0;
1184 }
1185 
1186 /*
1187  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1188  *                              nfs_pageio_descriptor
1189  * @desc: pointer to io descriptor
1190  * @mirror_idx: pointer to mirror index
1191  */
1192 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1193                                        u32 mirror_idx)
1194 {
1195         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1196         u32 restore_idx = desc->pg_mirror_idx;
1197 
1198         if (nfs_pgio_has_mirroring(desc))
1199                 desc->pg_mirror_idx = mirror_idx;
1200         for (;;) {
1201                 nfs_pageio_doio(desc);
1202                 if (!mirror->pg_recoalesce)
1203                         break;
1204                 if (!nfs_do_recoalesce(desc))
1205                         break;
1206         }
1207         desc->pg_mirror_idx = restore_idx;
1208 }
1209 
1210 /*
1211  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1212  * @hdr - the pgio header to move request from
1213  * @desc - the pageio descriptor to add requests to
1214  *
1215  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1216  * to send them.
1217  *
1218  * Returns 0 on success and < 0 on error.
1219  */
1220 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1221                       struct nfs_pgio_header *hdr)
1222 {
1223         LIST_HEAD(failed);
1224 
1225         desc->pg_io_completion = hdr->io_completion;
1226         desc->pg_dreq = hdr->dreq;
1227         while (!list_empty(&hdr->pages)) {
1228                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1229 
1230                 nfs_list_remove_request(req);
1231                 if (!nfs_pageio_add_request(desc, req))
1232                         nfs_list_add_request(req, &failed);
1233         }
1234         nfs_pageio_complete(desc);
1235         if (!list_empty(&failed)) {
1236                 list_move(&failed, &hdr->pages);
1237                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1238         }
1239         return 0;
1240 }
1241 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1242 
1243 /**
1244  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1245  * @desc: pointer to io descriptor
1246  */
1247 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1248 {
1249         u32 midx;
1250 
1251         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1252                 nfs_pageio_complete_mirror(desc, midx);
1253 
1254         if (desc->pg_ops->pg_cleanup)
1255                 desc->pg_ops->pg_cleanup(desc);
1256         nfs_pageio_cleanup_mirroring(desc);
1257 }
1258 
1259 /**
1260  * nfs_pageio_cond_complete - Conditional I/O completion
1261  * @desc: pointer to io descriptor
1262  * @index: page index
1263  *
1264  * It is important to ensure that processes don't try to take locks
1265  * on non-contiguous ranges of pages as that might deadlock. This
1266  * function should be called before attempting to wait on a locked
1267  * nfs_page. It will complete the I/O if the page index 'index'
1268  * is not contiguous with the existing list of pages in 'desc'.
1269  */
1270 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1271 {
1272         struct nfs_pgio_mirror *mirror;
1273         struct nfs_page *prev;
1274         u32 midx;
1275 
1276         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1277                 mirror = &desc->pg_mirrors[midx];
1278                 if (!list_empty(&mirror->pg_list)) {
1279                         prev = nfs_list_entry(mirror->pg_list.prev);
1280                         if (index != prev->wb_index + 1) {
1281                                 nfs_pageio_complete(desc);
1282                                 break;
1283                         }
1284                 }
1285         }
1286 }
1287 
1288 int __init nfs_init_nfspagecache(void)
1289 {
1290         nfs_page_cachep = kmem_cache_create("nfs_page",
1291                                             sizeof(struct nfs_page),
1292                                             0, SLAB_HWCACHE_ALIGN,
1293                                             NULL);
1294         if (nfs_page_cachep == NULL)
1295                 return -ENOMEM;
1296 
1297         return 0;
1298 }
1299 
1300 void nfs_destroy_nfspagecache(void)
1301 {
1302         kmem_cache_destroy(nfs_page_cachep);
1303 }
1304 
1305 static const struct rpc_call_ops nfs_pgio_common_ops = {
1306         .rpc_call_prepare = nfs_pgio_prepare,
1307         .rpc_call_done = nfs_pgio_result,
1308         .rpc_release = nfs_pgio_release,
1309 };
1310 
1311 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1312         .pg_test = nfs_generic_pg_test,
1313         .pg_doio = nfs_generic_pg_pgios,
1314 };
1315 

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