xref: /openbmc/linux/fs/nfs/pagelist.c (revision da2ef666)
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