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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 static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
 33 {
 34         p->npages = pagecount;
 35         if (pagecount <= ARRAY_SIZE(p->page_array))
 36                 p->pagevec = p->page_array;
 37         else {
 38                 p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
 39                 if (!p->pagevec)
 40                         p->npages = 0;
 41         }
 42         return p->pagevec != NULL;
 43 }
 44 
 45 struct nfs_pgio_mirror *
 46 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
 47 {
 48         return nfs_pgio_has_mirroring(desc) ?
 49                 &desc->pg_mirrors[desc->pg_mirror_idx] :
 50                 &desc->pg_mirrors[0];
 51 }
 52 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
 53 
 54 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
 55                        struct nfs_pgio_header *hdr,
 56                        void (*release)(struct nfs_pgio_header *hdr))
 57 {
 58         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 59 
 60 
 61         hdr->req = nfs_list_entry(mirror->pg_list.next);
 62         hdr->inode = desc->pg_inode;
 63         hdr->cred = hdr->req->wb_context->cred;
 64         hdr->io_start = req_offset(hdr->req);
 65         hdr->good_bytes = mirror->pg_count;
 66         hdr->dreq = desc->pg_dreq;
 67         hdr->layout_private = desc->pg_layout_private;
 68         hdr->release = release;
 69         hdr->completion_ops = desc->pg_completion_ops;
 70         if (hdr->completion_ops->init_hdr)
 71                 hdr->completion_ops->init_hdr(hdr);
 72 
 73         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
 74 }
 75 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
 76 
 77 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
 78 {
 79         spin_lock(&hdr->lock);
 80         if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags)
 81             || pos < hdr->io_start + hdr->good_bytes) {
 82                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
 83                 hdr->good_bytes = pos - hdr->io_start;
 84                 hdr->error = error;
 85         }
 86         spin_unlock(&hdr->lock);
 87 }
 88 
 89 static inline struct nfs_page *
 90 nfs_page_alloc(void)
 91 {
 92         struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
 93         if (p)
 94                 INIT_LIST_HEAD(&p->wb_list);
 95         return p;
 96 }
 97 
 98 static inline void
 99 nfs_page_free(struct nfs_page *p)
100 {
101         kmem_cache_free(nfs_page_cachep, p);
102 }
103 
104 static void
105 nfs_iocounter_inc(struct nfs_io_counter *c)
106 {
107         atomic_inc(&c->io_count);
108 }
109 
110 static void
111 nfs_iocounter_dec(struct nfs_io_counter *c)
112 {
113         if (atomic_dec_and_test(&c->io_count)) {
114                 clear_bit(NFS_IO_INPROGRESS, &c->flags);
115                 smp_mb__after_atomic();
116                 wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
117         }
118 }
119 
120 static int
121 __nfs_iocounter_wait(struct nfs_io_counter *c)
122 {
123         wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
124         DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
125         int ret = 0;
126 
127         do {
128                 prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
129                 set_bit(NFS_IO_INPROGRESS, &c->flags);
130                 if (atomic_read(&c->io_count) == 0)
131                         break;
132                 ret = nfs_wait_bit_killable(&q.key, TASK_KILLABLE);
133         } while (atomic_read(&c->io_count) != 0 && !ret);
134         finish_wait(wq, &q.wait);
135         return ret;
136 }
137 
138 /**
139  * nfs_iocounter_wait - wait for i/o to complete
140  * @c: nfs_io_counter to use
141  *
142  * returns -ERESTARTSYS if interrupted by a fatal signal.
143  * Otherwise returns 0 once the io_count hits 0.
144  */
145 int
146 nfs_iocounter_wait(struct nfs_io_counter *c)
147 {
148         if (atomic_read(&c->io_count) == 0)
149                 return 0;
150         return __nfs_iocounter_wait(c);
151 }
152 
153 /*
154  * nfs_page_group_lock - lock the head of the page group
155  * @req - request in group that is to be locked
156  * @nonblock - if true don't block waiting for lock
157  *
158  * this lock must be held if modifying the page group list
159  *
160  * return 0 on success, < 0 on error: -EDELAY if nonblocking or the
161  * result from wait_on_bit_lock
162  *
163  * NOTE: calling with nonblock=false should always have set the
164  *       lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
165  *       with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
166  */
167 int
168 nfs_page_group_lock(struct nfs_page *req, bool nonblock)
169 {
170         struct nfs_page *head = req->wb_head;
171 
172         WARN_ON_ONCE(head != head->wb_head);
173 
174         if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
175                 return 0;
176 
177         if (!nonblock)
178                 return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
179                                 TASK_UNINTERRUPTIBLE);
180 
181         return -EAGAIN;
182 }
183 
184 /*
185  * nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
186  * @req - a request in the group
187  *
188  * This is a blocking call to wait for the group lock to be cleared.
189  */
190 void
191 nfs_page_group_lock_wait(struct nfs_page *req)
192 {
193         struct nfs_page *head = req->wb_head;
194 
195         WARN_ON_ONCE(head != head->wb_head);
196 
197         wait_on_bit(&head->wb_flags, PG_HEADLOCK,
198                 TASK_UNINTERRUPTIBLE);
199 }
200 
201 /*
202  * nfs_page_group_unlock - unlock the head of the page group
203  * @req - request in group that is to be unlocked
204  */
205 void
206 nfs_page_group_unlock(struct nfs_page *req)
207 {
208         struct nfs_page *head = req->wb_head;
209 
210         WARN_ON_ONCE(head != head->wb_head);
211 
212         smp_mb__before_atomic();
213         clear_bit(PG_HEADLOCK, &head->wb_flags);
214         smp_mb__after_atomic();
215         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
216 }
217 
218 /*
219  * nfs_page_group_sync_on_bit_locked
220  *
221  * must be called with page group lock held
222  */
223 static bool
224 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
225 {
226         struct nfs_page *head = req->wb_head;
227         struct nfs_page *tmp;
228 
229         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
230         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
231 
232         tmp = req->wb_this_page;
233         while (tmp != req) {
234                 if (!test_bit(bit, &tmp->wb_flags))
235                         return false;
236                 tmp = tmp->wb_this_page;
237         }
238 
239         /* true! reset all bits */
240         tmp = req;
241         do {
242                 clear_bit(bit, &tmp->wb_flags);
243                 tmp = tmp->wb_this_page;
244         } while (tmp != req);
245 
246         return true;
247 }
248 
249 /*
250  * nfs_page_group_sync_on_bit - set bit on current request, but only
251  *   return true if the bit is set for all requests in page group
252  * @req - request in page group
253  * @bit - PG_* bit that is used to sync page group
254  */
255 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
256 {
257         bool ret;
258 
259         nfs_page_group_lock(req, false);
260         ret = nfs_page_group_sync_on_bit_locked(req, bit);
261         nfs_page_group_unlock(req);
262 
263         return ret;
264 }
265 
266 /*
267  * nfs_page_group_init - Initialize the page group linkage for @req
268  * @req - a new nfs request
269  * @prev - the previous request in page group, or NULL if @req is the first
270  *         or only request in the group (the head).
271  */
272 static inline void
273 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
274 {
275         struct inode *inode;
276         WARN_ON_ONCE(prev == req);
277 
278         if (!prev) {
279                 /* a head request */
280                 req->wb_head = req;
281                 req->wb_this_page = req;
282         } else {
283                 /* a subrequest */
284                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
285                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
286                 req->wb_head = prev->wb_head;
287                 req->wb_this_page = prev->wb_this_page;
288                 prev->wb_this_page = req;
289 
290                 /* All subrequests take a ref on the head request until
291                  * nfs_page_group_destroy is called */
292                 kref_get(&req->wb_head->wb_kref);
293 
294                 /* grab extra ref and bump the request count if head request
295                  * has extra ref from the write/commit path to handle handoff
296                  * between write and commit lists. */
297                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
298                         inode = page_file_mapping(req->wb_page)->host;
299                         set_bit(PG_INODE_REF, &req->wb_flags);
300                         kref_get(&req->wb_kref);
301                         spin_lock(&inode->i_lock);
302                         NFS_I(inode)->nrequests++;
303                         spin_unlock(&inode->i_lock);
304                 }
305         }
306 }
307 
308 /*
309  * nfs_page_group_destroy - sync the destruction of page groups
310  * @req - request that no longer needs the page group
311  *
312  * releases the page group reference from each member once all
313  * members have called this function.
314  */
315 static void
316 nfs_page_group_destroy(struct kref *kref)
317 {
318         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
319         struct nfs_page *tmp, *next;
320 
321         /* subrequests must release the ref on the head request */
322         if (req->wb_head != req)
323                 nfs_release_request(req->wb_head);
324 
325         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
326                 return;
327 
328         tmp = req;
329         do {
330                 next = tmp->wb_this_page;
331                 /* unlink and free */
332                 tmp->wb_this_page = tmp;
333                 tmp->wb_head = tmp;
334                 nfs_free_request(tmp);
335                 tmp = next;
336         } while (tmp != req);
337 }
338 
339 /**
340  * nfs_create_request - Create an NFS read/write request.
341  * @ctx: open context to use
342  * @page: page to write
343  * @last: last nfs request created for this page group or NULL if head
344  * @offset: starting offset within the page for the write
345  * @count: number of bytes to read/write
346  *
347  * The page must be locked by the caller. This makes sure we never
348  * create two different requests for the same page.
349  * User should ensure it is safe to sleep in this function.
350  */
351 struct nfs_page *
352 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
353                    struct nfs_page *last, unsigned int offset,
354                    unsigned int count)
355 {
356         struct nfs_page         *req;
357         struct nfs_lock_context *l_ctx;
358 
359         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
360                 return ERR_PTR(-EBADF);
361         /* try to allocate the request struct */
362         req = nfs_page_alloc();
363         if (req == NULL)
364                 return ERR_PTR(-ENOMEM);
365 
366         /* get lock context early so we can deal with alloc failures */
367         l_ctx = nfs_get_lock_context(ctx);
368         if (IS_ERR(l_ctx)) {
369                 nfs_page_free(req);
370                 return ERR_CAST(l_ctx);
371         }
372         req->wb_lock_context = l_ctx;
373         nfs_iocounter_inc(&l_ctx->io_count);
374 
375         /* Initialize the request struct. Initially, we assume a
376          * long write-back delay. This will be adjusted in
377          * update_nfs_request below if the region is not locked. */
378         req->wb_page    = page;
379         req->wb_index   = page_file_index(page);
380         page_cache_get(page);
381         req->wb_offset  = offset;
382         req->wb_pgbase  = offset;
383         req->wb_bytes   = count;
384         req->wb_context = get_nfs_open_context(ctx);
385         kref_init(&req->wb_kref);
386         nfs_page_group_init(req, last);
387         return req;
388 }
389 
390 /**
391  * nfs_unlock_request - Unlock request and wake up sleepers.
392  * @req:
393  */
394 void nfs_unlock_request(struct nfs_page *req)
395 {
396         if (!NFS_WBACK_BUSY(req)) {
397                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
398                 BUG();
399         }
400         smp_mb__before_atomic();
401         clear_bit(PG_BUSY, &req->wb_flags);
402         smp_mb__after_atomic();
403         wake_up_bit(&req->wb_flags, PG_BUSY);
404 }
405 
406 /**
407  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
408  * @req:
409  */
410 void nfs_unlock_and_release_request(struct nfs_page *req)
411 {
412         nfs_unlock_request(req);
413         nfs_release_request(req);
414 }
415 
416 /*
417  * nfs_clear_request - Free up all resources allocated to the request
418  * @req:
419  *
420  * Release page and open context resources associated with a read/write
421  * request after it has completed.
422  */
423 static void nfs_clear_request(struct nfs_page *req)
424 {
425         struct page *page = req->wb_page;
426         struct nfs_open_context *ctx = req->wb_context;
427         struct nfs_lock_context *l_ctx = req->wb_lock_context;
428 
429         if (page != NULL) {
430                 page_cache_release(page);
431                 req->wb_page = NULL;
432         }
433         if (l_ctx != NULL) {
434                 nfs_iocounter_dec(&l_ctx->io_count);
435                 nfs_put_lock_context(l_ctx);
436                 req->wb_lock_context = NULL;
437         }
438         if (ctx != NULL) {
439                 put_nfs_open_context(ctx);
440                 req->wb_context = NULL;
441         }
442 }
443 
444 /**
445  * nfs_release_request - Release the count on an NFS read/write request
446  * @req: request to release
447  *
448  * Note: Should never be called with the spinlock held!
449  */
450 void nfs_free_request(struct nfs_page *req)
451 {
452         WARN_ON_ONCE(req->wb_this_page != req);
453 
454         /* extra debug: make sure no sync bits are still set */
455         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
456         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
457         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
458         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
459         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
460 
461         /* Release struct file and open context */
462         nfs_clear_request(req);
463         nfs_page_free(req);
464 }
465 
466 void nfs_release_request(struct nfs_page *req)
467 {
468         kref_put(&req->wb_kref, nfs_page_group_destroy);
469 }
470 
471 /**
472  * nfs_wait_on_request - Wait for a request to complete.
473  * @req: request to wait upon.
474  *
475  * Interruptible by fatal signals only.
476  * The user is responsible for holding a count on the request.
477  */
478 int
479 nfs_wait_on_request(struct nfs_page *req)
480 {
481         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
482                               TASK_UNINTERRUPTIBLE);
483 }
484 
485 /*
486  * nfs_generic_pg_test - determine if requests can be coalesced
487  * @desc: pointer to descriptor
488  * @prev: previous request in desc, or NULL
489  * @req: this request
490  *
491  * Returns zero if @req can be coalesced into @desc, otherwise it returns
492  * the size of the request.
493  */
494 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
495                            struct nfs_page *prev, struct nfs_page *req)
496 {
497         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
498 
499 
500         if (mirror->pg_count > mirror->pg_bsize) {
501                 /* should never happen */
502                 WARN_ON_ONCE(1);
503                 return 0;
504         }
505 
506         /*
507          * Limit the request size so that we can still allocate a page array
508          * for it without upsetting the slab allocator.
509          */
510         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
511                         sizeof(struct page *) > PAGE_SIZE)
512                 return 0;
513 
514         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
515 }
516 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
517 
518 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
519 {
520         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
521 
522         if (hdr) {
523                 INIT_LIST_HEAD(&hdr->pages);
524                 spin_lock_init(&hdr->lock);
525                 hdr->rw_ops = ops;
526         }
527         return hdr;
528 }
529 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
530 
531 /**
532  * nfs_pgio_data_destroy - make @hdr suitable for reuse
533  *
534  * Frees memory and releases refs from nfs_generic_pgio, so that it may
535  * be called again.
536  *
537  * @hdr: A header that has had nfs_generic_pgio called
538  */
539 static void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
540 {
541         if (hdr->args.context)
542                 put_nfs_open_context(hdr->args.context);
543         if (hdr->page_array.pagevec != hdr->page_array.page_array)
544                 kfree(hdr->page_array.pagevec);
545 }
546 
547 /*
548  * nfs_pgio_header_free - Free a read or write header
549  * @hdr: The header to free
550  */
551 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
552 {
553         nfs_pgio_data_destroy(hdr);
554         hdr->rw_ops->rw_free_header(hdr);
555 }
556 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
557 
558 /**
559  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
560  * @hdr: The pageio hdr
561  * @count: Number of bytes to read
562  * @offset: Initial offset
563  * @how: How to commit data (writes only)
564  * @cinfo: Commit information for the call (writes only)
565  */
566 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
567                               unsigned int count, unsigned int offset,
568                               int how, struct nfs_commit_info *cinfo)
569 {
570         struct nfs_page *req = hdr->req;
571 
572         /* Set up the RPC argument and reply structs
573          * NB: take care not to mess about with hdr->commit et al. */
574 
575         hdr->args.fh     = NFS_FH(hdr->inode);
576         hdr->args.offset = req_offset(req) + offset;
577         /* pnfs_set_layoutcommit needs this */
578         hdr->mds_offset = hdr->args.offset;
579         hdr->args.pgbase = req->wb_pgbase + offset;
580         hdr->args.pages  = hdr->page_array.pagevec;
581         hdr->args.count  = count;
582         hdr->args.context = get_nfs_open_context(req->wb_context);
583         hdr->args.lock_context = req->wb_lock_context;
584         hdr->args.stable  = NFS_UNSTABLE;
585         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
586         case 0:
587                 break;
588         case FLUSH_COND_STABLE:
589                 if (nfs_reqs_to_commit(cinfo))
590                         break;
591         default:
592                 hdr->args.stable = NFS_FILE_SYNC;
593         }
594 
595         hdr->res.fattr   = &hdr->fattr;
596         hdr->res.count   = 0;
597         hdr->res.eof     = 0;
598         hdr->res.verf    = &hdr->verf;
599         nfs_fattr_init(&hdr->fattr);
600 }
601 
602 /**
603  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
604  * @task: The current task
605  * @calldata: pageio header to prepare
606  */
607 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
608 {
609         struct nfs_pgio_header *hdr = calldata;
610         int err;
611         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
612         if (err)
613                 rpc_exit(task, err);
614 }
615 
616 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
617                       struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
618                       const struct rpc_call_ops *call_ops, int how, int flags)
619 {
620         struct rpc_task *task;
621         struct rpc_message msg = {
622                 .rpc_argp = &hdr->args,
623                 .rpc_resp = &hdr->res,
624                 .rpc_cred = cred,
625         };
626         struct rpc_task_setup task_setup_data = {
627                 .rpc_client = clnt,
628                 .task = &hdr->task,
629                 .rpc_message = &msg,
630                 .callback_ops = call_ops,
631                 .callback_data = hdr,
632                 .workqueue = nfsiod_workqueue,
633                 .flags = RPC_TASK_ASYNC | flags,
634         };
635         int ret = 0;
636 
637         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
638 
639         dprintk("NFS: initiated pgio call "
640                 "(req %s/%llu, %u bytes @ offset %llu)\n",
641                 hdr->inode->i_sb->s_id,
642                 (unsigned long long)NFS_FILEID(hdr->inode),
643                 hdr->args.count,
644                 (unsigned long long)hdr->args.offset);
645 
646         task = rpc_run_task(&task_setup_data);
647         if (IS_ERR(task)) {
648                 ret = PTR_ERR(task);
649                 goto out;
650         }
651         if (how & FLUSH_SYNC) {
652                 ret = rpc_wait_for_completion_task(task);
653                 if (ret == 0)
654                         ret = task->tk_status;
655         }
656         rpc_put_task(task);
657 out:
658         return ret;
659 }
660 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
661 
662 /**
663  * nfs_pgio_error - Clean up from a pageio error
664  * @desc: IO descriptor
665  * @hdr: pageio header
666  */
667 static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
668                           struct nfs_pgio_header *hdr)
669 {
670         struct nfs_pgio_mirror *mirror;
671         u32 midx;
672 
673         set_bit(NFS_IOHDR_REDO, &hdr->flags);
674         hdr->completion_ops->completion(hdr);
675         /* TODO: Make sure it's right to clean up all mirrors here
676          *       and not just hdr->pgio_mirror_idx */
677         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
678                 mirror = &desc->pg_mirrors[midx];
679                 desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
680         }
681         return -ENOMEM;
682 }
683 
684 /**
685  * nfs_pgio_release - Release pageio data
686  * @calldata: The pageio header to release
687  */
688 static void nfs_pgio_release(void *calldata)
689 {
690         struct nfs_pgio_header *hdr = calldata;
691         hdr->completion_ops->completion(hdr);
692 }
693 
694 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
695                                    unsigned int bsize)
696 {
697         INIT_LIST_HEAD(&mirror->pg_list);
698         mirror->pg_bytes_written = 0;
699         mirror->pg_count = 0;
700         mirror->pg_bsize = bsize;
701         mirror->pg_base = 0;
702         mirror->pg_recoalesce = 0;
703 }
704 
705 /**
706  * nfs_pageio_init - initialise a page io descriptor
707  * @desc: pointer to descriptor
708  * @inode: pointer to inode
709  * @pg_ops: pointer to pageio operations
710  * @compl_ops: pointer to pageio completion operations
711  * @rw_ops: pointer to nfs read/write operations
712  * @bsize: io block size
713  * @io_flags: extra parameters for the io function
714  */
715 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
716                      struct inode *inode,
717                      const struct nfs_pageio_ops *pg_ops,
718                      const struct nfs_pgio_completion_ops *compl_ops,
719                      const struct nfs_rw_ops *rw_ops,
720                      size_t bsize,
721                      int io_flags)
722 {
723         struct nfs_pgio_mirror *new;
724         int i;
725 
726         desc->pg_moreio = 0;
727         desc->pg_inode = inode;
728         desc->pg_ops = pg_ops;
729         desc->pg_completion_ops = compl_ops;
730         desc->pg_rw_ops = rw_ops;
731         desc->pg_ioflags = io_flags;
732         desc->pg_error = 0;
733         desc->pg_lseg = NULL;
734         desc->pg_dreq = NULL;
735         desc->pg_layout_private = NULL;
736         desc->pg_bsize = bsize;
737 
738         desc->pg_mirror_count = 1;
739         desc->pg_mirror_idx = 0;
740 
741         if (pg_ops->pg_get_mirror_count) {
742                 /* until we have a request, we don't have an lseg and no
743                  * idea how many mirrors there will be */
744                 new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
745                               sizeof(struct nfs_pgio_mirror), GFP_KERNEL);
746                 desc->pg_mirrors_dynamic = new;
747                 desc->pg_mirrors = new;
748 
749                 for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
750                         nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
751         } else {
752                 desc->pg_mirrors_dynamic = NULL;
753                 desc->pg_mirrors = desc->pg_mirrors_static;
754                 nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
755         }
756 }
757 EXPORT_SYMBOL_GPL(nfs_pageio_init);
758 
759 /**
760  * nfs_pgio_result - Basic pageio error handling
761  * @task: The task that ran
762  * @calldata: Pageio header to check
763  */
764 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
765 {
766         struct nfs_pgio_header *hdr = calldata;
767         struct inode *inode = hdr->inode;
768 
769         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
770                 task->tk_pid, task->tk_status);
771 
772         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
773                 return;
774         if (task->tk_status < 0)
775                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
776         else
777                 hdr->rw_ops->rw_result(task, hdr);
778 }
779 
780 /*
781  * Create an RPC task for the given read or write request and kick it.
782  * The page must have been locked by the caller.
783  *
784  * It may happen that the page we're passed is not marked dirty.
785  * This is the case if nfs_updatepage detects a conflicting request
786  * that has been written but not committed.
787  */
788 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
789                      struct nfs_pgio_header *hdr)
790 {
791         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
792 
793         struct nfs_page         *req;
794         struct page             **pages,
795                                 *last_page;
796         struct list_head *head = &mirror->pg_list;
797         struct nfs_commit_info cinfo;
798         unsigned int pagecount, pageused;
799 
800         pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
801         if (!nfs_pgarray_set(&hdr->page_array, pagecount))
802                 return nfs_pgio_error(desc, hdr);
803 
804         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
805         pages = hdr->page_array.pagevec;
806         last_page = NULL;
807         pageused = 0;
808         while (!list_empty(head)) {
809                 req = nfs_list_entry(head->next);
810                 nfs_list_remove_request(req);
811                 nfs_list_add_request(req, &hdr->pages);
812 
813                 if (!last_page || last_page != req->wb_page) {
814                         pageused++;
815                         if (pageused > pagecount)
816                                 break;
817                         *pages++ = last_page = req->wb_page;
818                 }
819         }
820         if (WARN_ON_ONCE(pageused != pagecount))
821                 return nfs_pgio_error(desc, hdr);
822 
823         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
824             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
825                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
826 
827         /* Set up the argument struct */
828         nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
829         desc->pg_rpc_callops = &nfs_pgio_common_ops;
830         return 0;
831 }
832 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
833 
834 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
835 {
836         struct nfs_pgio_mirror *mirror;
837         struct nfs_pgio_header *hdr;
838         int ret;
839 
840         mirror = nfs_pgio_current_mirror(desc);
841 
842         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
843         if (!hdr) {
844                 /* TODO: make sure this is right with mirroring - or
845                  *       should it back out all mirrors? */
846                 desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
847                 return -ENOMEM;
848         }
849         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
850         ret = nfs_generic_pgio(desc, hdr);
851         if (ret == 0)
852                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
853                                         hdr,
854                                         hdr->cred,
855                                         NFS_PROTO(hdr->inode),
856                                         desc->pg_rpc_callops,
857                                         desc->pg_ioflags, 0);
858         return ret;
859 }
860 
861 /*
862  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
863  *                              by calling the pg_get_mirror_count op
864  */
865 static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
866                                        struct nfs_page *req)
867 {
868         int mirror_count = 1;
869 
870         if (!pgio->pg_ops->pg_get_mirror_count)
871                 return 0;
872 
873         mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
874 
875         if (pgio->pg_error < 0)
876                 return pgio->pg_error;
877 
878         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
879                 return -EINVAL;
880 
881         if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
882                 return -EINVAL;
883 
884         pgio->pg_mirror_count = mirror_count;
885 
886         return 0;
887 }
888 
889 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
890 {
891         pgio->pg_mirror_count = 1;
892         pgio->pg_mirror_idx = 0;
893         pgio->pg_mirrors = pgio->pg_mirrors_static;
894         kfree(pgio->pg_mirrors_dynamic);
895         pgio->pg_mirrors_dynamic = NULL;
896 }
897 
898 static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
899                 const struct nfs_open_context *ctx2)
900 {
901         return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
902 }
903 
904 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
905                 const struct nfs_lock_context *l2)
906 {
907         return l1->lockowner.l_owner == l2->lockowner.l_owner
908                 && l1->lockowner.l_pid == l2->lockowner.l_pid;
909 }
910 
911 /**
912  * nfs_can_coalesce_requests - test two requests for compatibility
913  * @prev: pointer to nfs_page
914  * @req: pointer to nfs_page
915  *
916  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
917  * page data area they describe is contiguous, and that their RPC
918  * credentials, NFSv4 open state, and lockowners are the same.
919  *
920  * Return 'true' if this is the case, else return 'false'.
921  */
922 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
923                                       struct nfs_page *req,
924                                       struct nfs_pageio_descriptor *pgio)
925 {
926         size_t size;
927         struct file_lock_context *flctx;
928 
929         if (prev) {
930                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
931                         return false;
932                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
933                 if (flctx != NULL &&
934                     !(list_empty_careful(&flctx->flc_posix) &&
935                       list_empty_careful(&flctx->flc_flock)) &&
936                     !nfs_match_lock_context(req->wb_lock_context,
937                                             prev->wb_lock_context))
938                         return false;
939                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
940                         return false;
941                 if (req->wb_page == prev->wb_page) {
942                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
943                                 return false;
944                 } else {
945                         if (req->wb_pgbase != 0 ||
946                             prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
947                                 return false;
948                 }
949         }
950         size = pgio->pg_ops->pg_test(pgio, prev, req);
951         WARN_ON_ONCE(size > req->wb_bytes);
952         if (size && size < req->wb_bytes)
953                 req->wb_bytes = size;
954         return size > 0;
955 }
956 
957 /**
958  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
959  * @desc: destination io descriptor
960  * @req: request
961  *
962  * Returns true if the request 'req' was successfully coalesced into the
963  * existing list of pages 'desc'.
964  */
965 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
966                                      struct nfs_page *req)
967 {
968         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
969 
970         struct nfs_page *prev = NULL;
971 
972         if (mirror->pg_count != 0) {
973                 prev = nfs_list_entry(mirror->pg_list.prev);
974         } else {
975                 if (desc->pg_ops->pg_init)
976                         desc->pg_ops->pg_init(desc, req);
977                 if (desc->pg_error < 0)
978                         return 0;
979                 mirror->pg_base = req->wb_pgbase;
980         }
981         if (!nfs_can_coalesce_requests(prev, req, desc))
982                 return 0;
983         nfs_list_remove_request(req);
984         nfs_list_add_request(req, &mirror->pg_list);
985         mirror->pg_count += req->wb_bytes;
986         return 1;
987 }
988 
989 /*
990  * Helper for nfs_pageio_add_request and nfs_pageio_complete
991  */
992 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
993 {
994         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
995 
996         if (!list_empty(&mirror->pg_list)) {
997                 int error = desc->pg_ops->pg_doio(desc);
998                 if (error < 0)
999                         desc->pg_error = error;
1000                 if (list_empty(&mirror->pg_list)) {
1001                         mirror->pg_bytes_written += mirror->pg_count;
1002                         mirror->pg_count = 0;
1003                         mirror->pg_base = 0;
1004                         mirror->pg_recoalesce = 0;
1005                 }
1006         }
1007 }
1008 
1009 /**
1010  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
1011  * @desc: destination io descriptor
1012  * @req: request
1013  *
1014  * This may split a request into subrequests which are all part of the
1015  * same page group.
1016  *
1017  * Returns true if the request 'req' was successfully coalesced into the
1018  * existing list of pages 'desc'.
1019  */
1020 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1021                            struct nfs_page *req)
1022 {
1023         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1024 
1025         struct nfs_page *subreq;
1026         unsigned int bytes_left = 0;
1027         unsigned int offset, pgbase;
1028 
1029         nfs_page_group_lock(req, false);
1030 
1031         subreq = req;
1032         bytes_left = subreq->wb_bytes;
1033         offset = subreq->wb_offset;
1034         pgbase = subreq->wb_pgbase;
1035 
1036         do {
1037                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1038                         /* make sure pg_test call(s) did nothing */
1039                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1040                         WARN_ON_ONCE(subreq->wb_offset != offset);
1041                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1042 
1043                         nfs_page_group_unlock(req);
1044                         desc->pg_moreio = 1;
1045                         nfs_pageio_doio(desc);
1046                         if (desc->pg_error < 0)
1047                                 return 0;
1048                         if (mirror->pg_recoalesce)
1049                                 return 0;
1050                         /* retry add_request for this subreq */
1051                         nfs_page_group_lock(req, false);
1052                         continue;
1053                 }
1054 
1055                 /* check for buggy pg_test call(s) */
1056                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1057                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1058                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1059 
1060                 bytes_left -= subreq->wb_bytes;
1061                 offset += subreq->wb_bytes;
1062                 pgbase += subreq->wb_bytes;
1063 
1064                 if (bytes_left) {
1065                         subreq = nfs_create_request(req->wb_context,
1066                                         req->wb_page,
1067                                         subreq, pgbase, bytes_left);
1068                         if (IS_ERR(subreq))
1069                                 goto err_ptr;
1070                         nfs_lock_request(subreq);
1071                         subreq->wb_offset  = offset;
1072                         subreq->wb_index = req->wb_index;
1073                 }
1074         } while (bytes_left > 0);
1075 
1076         nfs_page_group_unlock(req);
1077         return 1;
1078 err_ptr:
1079         desc->pg_error = PTR_ERR(subreq);
1080         nfs_page_group_unlock(req);
1081         return 0;
1082 }
1083 
1084 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1085 {
1086         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1087         LIST_HEAD(head);
1088 
1089         do {
1090                 list_splice_init(&mirror->pg_list, &head);
1091                 mirror->pg_count = 0;
1092                 mirror->pg_base = 0;
1093                 mirror->pg_recoalesce = 0;
1094 
1095                 while (!list_empty(&head)) {
1096                         struct nfs_page *req;
1097 
1098                         req = list_first_entry(&head, struct nfs_page, wb_list);
1099                         if (__nfs_pageio_add_request(desc, req))
1100                                 continue;
1101                         if (desc->pg_error < 0) {
1102                                 list_splice_tail(&head, &mirror->pg_list);
1103                                 mirror->pg_recoalesce = 1;
1104                                 return 0;
1105                         }
1106                         break;
1107                 }
1108         } while (mirror->pg_recoalesce);
1109         return 1;
1110 }
1111 
1112 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1113                 struct nfs_page *req)
1114 {
1115         int ret;
1116 
1117         do {
1118                 ret = __nfs_pageio_add_request(desc, req);
1119                 if (ret)
1120                         break;
1121                 if (desc->pg_error < 0)
1122                         break;
1123                 ret = nfs_do_recoalesce(desc);
1124         } while (ret);
1125 
1126         return ret;
1127 }
1128 
1129 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1130                            struct nfs_page *req)
1131 {
1132         u32 midx;
1133         unsigned int pgbase, offset, bytes;
1134         struct nfs_page *dupreq, *lastreq;
1135 
1136         pgbase = req->wb_pgbase;
1137         offset = req->wb_offset;
1138         bytes = req->wb_bytes;
1139 
1140         nfs_pageio_setup_mirroring(desc, req);
1141         if (desc->pg_error < 0)
1142                 return 0;
1143 
1144         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1145                 if (midx) {
1146                         nfs_page_group_lock(req, false);
1147 
1148                         /* find the last request */
1149                         for (lastreq = req->wb_head;
1150                              lastreq->wb_this_page != req->wb_head;
1151                              lastreq = lastreq->wb_this_page)
1152                                 ;
1153 
1154                         dupreq = nfs_create_request(req->wb_context,
1155                                         req->wb_page, lastreq, pgbase, bytes);
1156 
1157                         if (IS_ERR(dupreq)) {
1158                                 nfs_page_group_unlock(req);
1159                                 return 0;
1160                         }
1161 
1162                         nfs_lock_request(dupreq);
1163                         nfs_page_group_unlock(req);
1164                         dupreq->wb_offset = offset;
1165                         dupreq->wb_index = req->wb_index;
1166                 } else
1167                         dupreq = req;
1168 
1169                 if (nfs_pgio_has_mirroring(desc))
1170                         desc->pg_mirror_idx = midx;
1171                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1172                         return 0;
1173         }
1174 
1175         return 1;
1176 }
1177 
1178 /*
1179  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1180  *                              nfs_pageio_descriptor
1181  * @desc: pointer to io descriptor
1182  * @mirror_idx: pointer to mirror index
1183  */
1184 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1185                                        u32 mirror_idx)
1186 {
1187         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1188         u32 restore_idx = desc->pg_mirror_idx;
1189 
1190         if (nfs_pgio_has_mirroring(desc))
1191                 desc->pg_mirror_idx = mirror_idx;
1192         for (;;) {
1193                 nfs_pageio_doio(desc);
1194                 if (desc->pg_error < 0 || !mirror->pg_recoalesce)
1195                         break;
1196                 if (!nfs_do_recoalesce(desc))
1197                         break;
1198         }
1199         desc->pg_mirror_idx = restore_idx;
1200 }
1201 
1202 /*
1203  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1204  * @hdr - the pgio header to move request from
1205  * @desc - the pageio descriptor to add requests to
1206  *
1207  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1208  * to send them.
1209  *
1210  * Returns 0 on success and < 0 on error.
1211  */
1212 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1213                       struct nfs_pgio_header *hdr)
1214 {
1215         LIST_HEAD(failed);
1216 
1217         desc->pg_dreq = hdr->dreq;
1218         while (!list_empty(&hdr->pages)) {
1219                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1220 
1221                 nfs_list_remove_request(req);
1222                 if (!nfs_pageio_add_request(desc, req))
1223                         nfs_list_add_request(req, &failed);
1224         }
1225         nfs_pageio_complete(desc);
1226         if (!list_empty(&failed)) {
1227                 list_move(&failed, &hdr->pages);
1228                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1229         }
1230         return 0;
1231 }
1232 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1233 
1234 /**
1235  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1236  * @desc: pointer to io descriptor
1237  */
1238 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1239 {
1240         u32 midx;
1241 
1242         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1243                 nfs_pageio_complete_mirror(desc, midx);
1244 
1245         if (desc->pg_ops->pg_cleanup)
1246                 desc->pg_ops->pg_cleanup(desc);
1247         nfs_pageio_cleanup_mirroring(desc);
1248 }
1249 
1250 /**
1251  * nfs_pageio_cond_complete - Conditional I/O completion
1252  * @desc: pointer to io descriptor
1253  * @index: page index
1254  *
1255  * It is important to ensure that processes don't try to take locks
1256  * on non-contiguous ranges of pages as that might deadlock. This
1257  * function should be called before attempting to wait on a locked
1258  * nfs_page. It will complete the I/O if the page index 'index'
1259  * is not contiguous with the existing list of pages in 'desc'.
1260  */
1261 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1262 {
1263         struct nfs_pgio_mirror *mirror;
1264         struct nfs_page *prev;
1265         u32 midx;
1266 
1267         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1268                 mirror = &desc->pg_mirrors[midx];
1269                 if (!list_empty(&mirror->pg_list)) {
1270                         prev = nfs_list_entry(mirror->pg_list.prev);
1271                         if (index != prev->wb_index + 1) {
1272                                 nfs_pageio_complete(desc);
1273                                 break;
1274                         }
1275                 }
1276         }
1277 }
1278 
1279 /*
1280  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
1281  */
1282 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
1283 {
1284         nfs_pageio_complete(pgio);
1285 }
1286 
1287 int __init nfs_init_nfspagecache(void)
1288 {
1289         nfs_page_cachep = kmem_cache_create("nfs_page",
1290                                             sizeof(struct nfs_page),
1291                                             0, SLAB_HWCACHE_ALIGN,
1292                                             NULL);
1293         if (nfs_page_cachep == NULL)
1294                 return -ENOMEM;
1295 
1296         return 0;
1297 }
1298 
1299 void nfs_destroy_nfspagecache(void)
1300 {
1301         kmem_cache_destroy(nfs_page_cachep);
1302 }
1303 
1304 static const struct rpc_call_ops nfs_pgio_common_ops = {
1305         .rpc_call_prepare = nfs_pgio_prepare,
1306         .rpc_call_done = nfs_pgio_result,
1307         .rpc_release = nfs_pgio_release,
1308 };
1309 
1310 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1311         .pg_test = nfs_generic_pg_test,
1312         .pg_doio = nfs_generic_pg_pgios,
1313 };
1314 

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