2 * linux/fs/nfs/pagelist.c
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.
8 * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
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>
27 #define NFSDBG_FACILITY NFSDBG_PAGECACHE
29 static struct kmem_cache *nfs_page_cachep;
30 static const struct rpc_call_ops nfs_pgio_common_ops;
32 static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
34 p->npages = pagecount;
35 if (pagecount <= ARRAY_SIZE(p->page_array))
36 p->pagevec = p->page_array;
38 p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
42 return p->pagevec != NULL;
45 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
46 struct nfs_pgio_header *hdr,
47 void (*release)(struct nfs_pgio_header *hdr))
49 hdr->req = nfs_list_entry(desc->pg_list.next);
50 hdr->inode = desc->pg_inode;
51 hdr->cred = hdr->req->wb_context->cred;
52 hdr->io_start = req_offset(hdr->req);
53 hdr->good_bytes = desc->pg_count;
54 hdr->dreq = desc->pg_dreq;
55 hdr->layout_private = desc->pg_layout_private;
56 hdr->release = release;
57 hdr->completion_ops = desc->pg_completion_ops;
58 if (hdr->completion_ops->init_hdr)
59 hdr->completion_ops->init_hdr(hdr);
61 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
63 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
65 spin_lock(&hdr->lock);
66 if (pos < hdr->io_start + hdr->good_bytes) {
67 set_bit(NFS_IOHDR_ERROR, &hdr->flags);
68 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
69 hdr->good_bytes = pos - hdr->io_start;
72 spin_unlock(&hdr->lock);
75 static inline struct nfs_page *
78 struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
80 INIT_LIST_HEAD(&p->wb_list);
85 nfs_page_free(struct nfs_page *p)
87 kmem_cache_free(nfs_page_cachep, p);
91 nfs_iocounter_inc(struct nfs_io_counter *c)
93 atomic_inc(&c->io_count);
97 nfs_iocounter_dec(struct nfs_io_counter *c)
99 if (atomic_dec_and_test(&c->io_count)) {
100 clear_bit(NFS_IO_INPROGRESS, &c->flags);
101 smp_mb__after_atomic();
102 wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
107 __nfs_iocounter_wait(struct nfs_io_counter *c)
109 wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
110 DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
114 prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
115 set_bit(NFS_IO_INPROGRESS, &c->flags);
116 if (atomic_read(&c->io_count) == 0)
118 ret = nfs_wait_bit_killable(&c->flags);
119 } while (atomic_read(&c->io_count) != 0);
120 finish_wait(wq, &q.wait);
125 * nfs_iocounter_wait - wait for i/o to complete
126 * @c: nfs_io_counter to use
128 * returns -ERESTARTSYS if interrupted by a fatal signal.
129 * Otherwise returns 0 once the io_count hits 0.
132 nfs_iocounter_wait(struct nfs_io_counter *c)
134 if (atomic_read(&c->io_count) == 0)
136 return __nfs_iocounter_wait(c);
139 static int nfs_wait_bit_uninterruptible(void *word)
146 * nfs_page_group_lock - lock the head of the page group
147 * @req - request in group that is to be locked
149 * this lock must be held if modifying the page group list
152 nfs_page_group_lock(struct nfs_page *req)
154 struct nfs_page *head = req->wb_head;
156 WARN_ON_ONCE(head != head->wb_head);
158 wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
159 nfs_wait_bit_uninterruptible,
160 TASK_UNINTERRUPTIBLE);
164 * nfs_page_group_unlock - unlock the head of the page group
165 * @req - request in group that is to be unlocked
168 nfs_page_group_unlock(struct nfs_page *req)
170 struct nfs_page *head = req->wb_head;
172 WARN_ON_ONCE(head != head->wb_head);
174 smp_mb__before_atomic();
175 clear_bit(PG_HEADLOCK, &head->wb_flags);
176 smp_mb__after_atomic();
177 wake_up_bit(&head->wb_flags, PG_HEADLOCK);
181 * nfs_page_group_sync_on_bit_locked
183 * must be called with page group lock held
186 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
188 struct nfs_page *head = req->wb_head;
189 struct nfs_page *tmp;
191 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
192 WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
194 tmp = req->wb_this_page;
196 if (!test_bit(bit, &tmp->wb_flags))
198 tmp = tmp->wb_this_page;
201 /* true! reset all bits */
204 clear_bit(bit, &tmp->wb_flags);
205 tmp = tmp->wb_this_page;
206 } while (tmp != req);
212 * nfs_page_group_sync_on_bit - set bit on current request, but only
213 * return true if the bit is set for all requests in page group
214 * @req - request in page group
215 * @bit - PG_* bit that is used to sync page group
217 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
221 nfs_page_group_lock(req);
222 ret = nfs_page_group_sync_on_bit_locked(req, bit);
223 nfs_page_group_unlock(req);
229 * nfs_page_group_init - Initialize the page group linkage for @req
230 * @req - a new nfs request
231 * @prev - the previous request in page group, or NULL if @req is the first
232 * or only request in the group (the head).
235 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
237 WARN_ON_ONCE(prev == req);
242 req->wb_this_page = req;
245 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
246 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
247 req->wb_head = prev->wb_head;
248 req->wb_this_page = prev->wb_this_page;
249 prev->wb_this_page = req;
251 /* All subrequests take a ref on the head request until
252 * nfs_page_group_destroy is called */
253 kref_get(&req->wb_head->wb_kref);
255 /* grab extra ref if head request has extra ref from
256 * the write/commit path to handle handoff between write
257 * and commit lists */
258 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
259 set_bit(PG_INODE_REF, &req->wb_flags);
260 kref_get(&req->wb_kref);
266 * nfs_page_group_destroy - sync the destruction of page groups
267 * @req - request that no longer needs the page group
269 * releases the page group reference from each member once all
270 * members have called this function.
273 nfs_page_group_destroy(struct kref *kref)
275 struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
276 struct nfs_page *tmp, *next;
278 /* subrequests must release the ref on the head request */
279 if (req->wb_head != req)
280 nfs_release_request(req->wb_head);
282 if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
287 next = tmp->wb_this_page;
288 /* unlink and free */
289 tmp->wb_this_page = tmp;
291 nfs_free_request(tmp);
293 } while (tmp != req);
297 * nfs_create_request - Create an NFS read/write request.
298 * @ctx: open context to use
299 * @page: page to write
300 * @last: last nfs request created for this page group or NULL if head
301 * @offset: starting offset within the page for the write
302 * @count: number of bytes to read/write
304 * The page must be locked by the caller. This makes sure we never
305 * create two different requests for the same page.
306 * User should ensure it is safe to sleep in this function.
309 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
310 struct nfs_page *last, unsigned int offset,
313 struct nfs_page *req;
314 struct nfs_lock_context *l_ctx;
316 if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
317 return ERR_PTR(-EBADF);
318 /* try to allocate the request struct */
319 req = nfs_page_alloc();
321 return ERR_PTR(-ENOMEM);
323 /* get lock context early so we can deal with alloc failures */
324 l_ctx = nfs_get_lock_context(ctx);
327 return ERR_CAST(l_ctx);
329 req->wb_lock_context = l_ctx;
330 nfs_iocounter_inc(&l_ctx->io_count);
332 /* Initialize the request struct. Initially, we assume a
333 * long write-back delay. This will be adjusted in
334 * update_nfs_request below if the region is not locked. */
336 req->wb_index = page_file_index(page);
337 page_cache_get(page);
338 req->wb_offset = offset;
339 req->wb_pgbase = offset;
340 req->wb_bytes = count;
341 req->wb_context = get_nfs_open_context(ctx);
342 kref_init(&req->wb_kref);
343 nfs_page_group_init(req, last);
348 * nfs_unlock_request - Unlock request and wake up sleepers.
351 void nfs_unlock_request(struct nfs_page *req)
353 if (!NFS_WBACK_BUSY(req)) {
354 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
357 smp_mb__before_atomic();
358 clear_bit(PG_BUSY, &req->wb_flags);
359 smp_mb__after_atomic();
360 wake_up_bit(&req->wb_flags, PG_BUSY);
364 * nfs_unlock_and_release_request - Unlock request and release the nfs_page
367 void nfs_unlock_and_release_request(struct nfs_page *req)
369 nfs_unlock_request(req);
370 nfs_release_request(req);
374 * nfs_clear_request - Free up all resources allocated to the request
377 * Release page and open context resources associated with a read/write
378 * request after it has completed.
380 static void nfs_clear_request(struct nfs_page *req)
382 struct page *page = req->wb_page;
383 struct nfs_open_context *ctx = req->wb_context;
384 struct nfs_lock_context *l_ctx = req->wb_lock_context;
387 page_cache_release(page);
391 nfs_iocounter_dec(&l_ctx->io_count);
392 nfs_put_lock_context(l_ctx);
393 req->wb_lock_context = NULL;
396 put_nfs_open_context(ctx);
397 req->wb_context = NULL;
402 * nfs_release_request - Release the count on an NFS read/write request
403 * @req: request to release
405 * Note: Should never be called with the spinlock held!
407 void nfs_free_request(struct nfs_page *req)
409 WARN_ON_ONCE(req->wb_this_page != req);
411 /* extra debug: make sure no sync bits are still set */
412 WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
413 WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
414 WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
415 WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
416 WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
418 /* Release struct file and open context */
419 nfs_clear_request(req);
423 void nfs_release_request(struct nfs_page *req)
425 kref_put(&req->wb_kref, nfs_page_group_destroy);
429 * nfs_wait_on_request - Wait for a request to complete.
430 * @req: request to wait upon.
432 * Interruptible by fatal signals only.
433 * The user is responsible for holding a count on the request.
436 nfs_wait_on_request(struct nfs_page *req)
438 return wait_on_bit(&req->wb_flags, PG_BUSY,
439 nfs_wait_bit_uninterruptible,
440 TASK_UNINTERRUPTIBLE);
444 * nfs_generic_pg_test - determine if requests can be coalesced
445 * @desc: pointer to descriptor
446 * @prev: previous request in desc, or NULL
449 * Returns zero if @req can be coalesced into @desc, otherwise it returns
450 * the size of the request.
452 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
453 struct nfs_page *prev, struct nfs_page *req)
455 if (desc->pg_count > desc->pg_bsize) {
456 /* should never happen */
461 return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
463 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
465 static inline struct nfs_rw_header *NFS_RW_HEADER(struct nfs_pgio_header *hdr)
467 return container_of(hdr, struct nfs_rw_header, header);
471 * nfs_rw_header_alloc - Allocate a header for a read or write
472 * @ops: Read or write function vector
474 struct nfs_rw_header *nfs_rw_header_alloc(const struct nfs_rw_ops *ops)
476 struct nfs_rw_header *header = ops->rw_alloc_header();
479 struct nfs_pgio_header *hdr = &header->header;
481 INIT_LIST_HEAD(&hdr->pages);
482 spin_lock_init(&hdr->lock);
483 atomic_set(&hdr->refcnt, 0);
488 EXPORT_SYMBOL_GPL(nfs_rw_header_alloc);
491 * nfs_rw_header_free - Free a read or write header
492 * @hdr: The header to free
494 void nfs_rw_header_free(struct nfs_pgio_header *hdr)
496 hdr->rw_ops->rw_free_header(NFS_RW_HEADER(hdr));
498 EXPORT_SYMBOL_GPL(nfs_rw_header_free);
501 * nfs_pgio_data_alloc - Allocate pageio data
502 * @hdr: The header making a request
503 * @pagecount: Number of pages to create
505 static struct nfs_pgio_data *nfs_pgio_data_alloc(struct nfs_pgio_header *hdr,
506 unsigned int pagecount)
508 struct nfs_pgio_data *data, *prealloc;
510 prealloc = &NFS_RW_HEADER(hdr)->rpc_data;
511 if (prealloc->header == NULL)
514 data = kzalloc(sizeof(*data), GFP_KERNEL);
518 if (nfs_pgarray_set(&data->pages, pagecount)) {
520 atomic_inc(&hdr->refcnt);
522 if (data != prealloc)
531 * nfs_pgio_data_release - Properly free pageio data
532 * @data: The data to release
534 void nfs_pgio_data_release(struct nfs_pgio_data *data)
536 struct nfs_pgio_header *hdr = data->header;
537 struct nfs_rw_header *pageio_header = NFS_RW_HEADER(hdr);
539 put_nfs_open_context(data->args.context);
540 if (data->pages.pagevec != data->pages.page_array)
541 kfree(data->pages.pagevec);
542 if (data == &pageio_header->rpc_data) {
546 if (atomic_dec_and_test(&hdr->refcnt))
547 hdr->completion_ops->completion(hdr);
548 /* Note: we only free the rpc_task after callbacks are done.
549 * See the comment in rpc_free_task() for why
553 EXPORT_SYMBOL_GPL(nfs_pgio_data_release);
556 * nfs_pgio_rpcsetup - Set up arguments for a pageio call
557 * @data: The pageio data
558 * @count: Number of bytes to read
559 * @offset: Initial offset
560 * @how: How to commit data (writes only)
561 * @cinfo: Commit information for the call (writes only)
563 static void nfs_pgio_rpcsetup(struct nfs_pgio_data *data,
564 unsigned int count, unsigned int offset,
565 int how, struct nfs_commit_info *cinfo)
567 struct nfs_page *req = data->header->req;
569 /* Set up the RPC argument and reply structs
570 * NB: take care not to mess about with data->commit et al. */
572 data->args.fh = NFS_FH(data->header->inode);
573 data->args.offset = req_offset(req) + offset;
574 /* pnfs_set_layoutcommit needs this */
575 data->mds_offset = data->args.offset;
576 data->args.pgbase = req->wb_pgbase + offset;
577 data->args.pages = data->pages.pagevec;
578 data->args.count = count;
579 data->args.context = get_nfs_open_context(req->wb_context);
580 data->args.lock_context = req->wb_lock_context;
581 data->args.stable = NFS_UNSTABLE;
582 switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
585 case FLUSH_COND_STABLE:
586 if (nfs_reqs_to_commit(cinfo))
589 data->args.stable = NFS_FILE_SYNC;
592 data->res.fattr = &data->fattr;
593 data->res.count = count;
595 data->res.verf = &data->verf;
596 nfs_fattr_init(&data->fattr);
600 * nfs_pgio_prepare - Prepare pageio data to go over the wire
601 * @task: The current task
602 * @calldata: pageio data to prepare
604 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
606 struct nfs_pgio_data *data = calldata;
608 err = NFS_PROTO(data->header->inode)->pgio_rpc_prepare(task, data);
613 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_data *data,
614 const struct rpc_call_ops *call_ops, int how, int flags)
616 struct rpc_task *task;
617 struct rpc_message msg = {
618 .rpc_argp = &data->args,
619 .rpc_resp = &data->res,
620 .rpc_cred = data->header->cred,
622 struct rpc_task_setup task_setup_data = {
626 .callback_ops = call_ops,
627 .callback_data = data,
628 .workqueue = nfsiod_workqueue,
629 .flags = RPC_TASK_ASYNC | flags,
633 data->header->rw_ops->rw_initiate(data, &msg, &task_setup_data, how);
635 dprintk("NFS: %5u initiated pgio call "
636 "(req %s/%llu, %u bytes @ offset %llu)\n",
638 data->header->inode->i_sb->s_id,
639 (unsigned long long)NFS_FILEID(data->header->inode),
641 (unsigned long long)data->args.offset);
643 task = rpc_run_task(&task_setup_data);
648 if (how & FLUSH_SYNC) {
649 ret = rpc_wait_for_completion_task(task);
651 ret = task->tk_status;
657 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
660 * nfs_pgio_error - Clean up from a pageio error
661 * @desc: IO descriptor
662 * @hdr: pageio header
664 static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
665 struct nfs_pgio_header *hdr)
667 set_bit(NFS_IOHDR_REDO, &hdr->flags);
668 nfs_pgio_data_release(hdr->data);
670 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
675 * nfs_pgio_release - Release pageio data
676 * @calldata: The pageio data to release
678 static void nfs_pgio_release(void *calldata)
680 struct nfs_pgio_data *data = calldata;
681 if (data->header->rw_ops->rw_release)
682 data->header->rw_ops->rw_release(data);
683 nfs_pgio_data_release(data);
687 * nfs_pageio_init - initialise a page io descriptor
688 * @desc: pointer to descriptor
689 * @inode: pointer to inode
690 * @doio: pointer to io function
691 * @bsize: io block size
692 * @io_flags: extra parameters for the io function
694 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
696 const struct nfs_pageio_ops *pg_ops,
697 const struct nfs_pgio_completion_ops *compl_ops,
698 const struct nfs_rw_ops *rw_ops,
702 INIT_LIST_HEAD(&desc->pg_list);
703 desc->pg_bytes_written = 0;
705 desc->pg_bsize = bsize;
708 desc->pg_recoalesce = 0;
709 desc->pg_inode = inode;
710 desc->pg_ops = pg_ops;
711 desc->pg_completion_ops = compl_ops;
712 desc->pg_rw_ops = rw_ops;
713 desc->pg_ioflags = io_flags;
715 desc->pg_lseg = NULL;
716 desc->pg_dreq = NULL;
717 desc->pg_layout_private = NULL;
719 EXPORT_SYMBOL_GPL(nfs_pageio_init);
722 * nfs_pgio_result - Basic pageio error handling
723 * @task: The task that ran
724 * @calldata: Pageio data to check
726 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
728 struct nfs_pgio_data *data = calldata;
729 struct inode *inode = data->header->inode;
731 dprintk("NFS: %s: %5u, (status %d)\n", __func__,
732 task->tk_pid, task->tk_status);
734 if (data->header->rw_ops->rw_done(task, data, inode) != 0)
736 if (task->tk_status < 0)
737 nfs_set_pgio_error(data->header, task->tk_status, data->args.offset);
739 data->header->rw_ops->rw_result(task, data);
743 * Create an RPC task for the given read or write request and kick it.
744 * The page must have been locked by the caller.
746 * It may happen that the page we're passed is not marked dirty.
747 * This is the case if nfs_updatepage detects a conflicting request
748 * that has been written but not committed.
750 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
751 struct nfs_pgio_header *hdr)
753 struct nfs_page *req;
755 struct nfs_pgio_data *data;
756 struct list_head *head = &desc->pg_list;
757 struct nfs_commit_info cinfo;
759 data = nfs_pgio_data_alloc(hdr, nfs_page_array_len(desc->pg_base,
762 return nfs_pgio_error(desc, hdr);
764 nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
765 pages = data->pages.pagevec;
766 while (!list_empty(head)) {
767 req = nfs_list_entry(head->next);
768 nfs_list_remove_request(req);
769 nfs_list_add_request(req, &hdr->pages);
770 *pages++ = req->wb_page;
773 if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
774 (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
775 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
777 /* Set up the argument struct */
778 nfs_pgio_rpcsetup(data, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
780 desc->pg_rpc_callops = &nfs_pgio_common_ops;
783 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
785 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
787 struct nfs_rw_header *rw_hdr;
788 struct nfs_pgio_header *hdr;
791 rw_hdr = nfs_rw_header_alloc(desc->pg_rw_ops);
793 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
796 hdr = &rw_hdr->header;
797 nfs_pgheader_init(desc, hdr, nfs_rw_header_free);
798 atomic_inc(&hdr->refcnt);
799 ret = nfs_generic_pgio(desc, hdr);
801 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
802 hdr->data, desc->pg_rpc_callops,
803 desc->pg_ioflags, 0);
804 if (atomic_dec_and_test(&hdr->refcnt))
805 hdr->completion_ops->completion(hdr);
809 static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
810 const struct nfs_open_context *ctx2)
812 return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
815 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
816 const struct nfs_lock_context *l2)
818 return l1->lockowner.l_owner == l2->lockowner.l_owner
819 && l1->lockowner.l_pid == l2->lockowner.l_pid;
823 * nfs_can_coalesce_requests - test two requests for compatibility
824 * @prev: pointer to nfs_page
825 * @req: pointer to nfs_page
827 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
828 * page data area they describe is contiguous, and that their RPC
829 * credentials, NFSv4 open state, and lockowners are the same.
831 * Return 'true' if this is the case, else return 'false'.
833 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
834 struct nfs_page *req,
835 struct nfs_pageio_descriptor *pgio)
840 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
842 if (req->wb_context->dentry->d_inode->i_flock != NULL &&
843 !nfs_match_lock_context(req->wb_lock_context,
844 prev->wb_lock_context))
846 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
849 size = pgio->pg_ops->pg_test(pgio, prev, req);
850 WARN_ON_ONCE(size > req->wb_bytes);
851 if (size && size < req->wb_bytes)
852 req->wb_bytes = size;
857 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
858 * @desc: destination io descriptor
861 * Returns true if the request 'req' was successfully coalesced into the
862 * existing list of pages 'desc'.
864 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
865 struct nfs_page *req)
867 struct nfs_page *prev = NULL;
868 if (desc->pg_count != 0) {
869 prev = nfs_list_entry(desc->pg_list.prev);
871 if (desc->pg_ops->pg_init)
872 desc->pg_ops->pg_init(desc, req);
873 desc->pg_base = req->wb_pgbase;
875 if (!nfs_can_coalesce_requests(prev, req, desc))
877 nfs_list_remove_request(req);
878 nfs_list_add_request(req, &desc->pg_list);
879 desc->pg_count += req->wb_bytes;
884 * Helper for nfs_pageio_add_request and nfs_pageio_complete
886 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
888 if (!list_empty(&desc->pg_list)) {
889 int error = desc->pg_ops->pg_doio(desc);
891 desc->pg_error = error;
893 desc->pg_bytes_written += desc->pg_count;
895 if (list_empty(&desc->pg_list)) {
902 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
903 * @desc: destination io descriptor
906 * This may split a request into subrequests which are all part of the
909 * Returns true if the request 'req' was successfully coalesced into the
910 * existing list of pages 'desc'.
912 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
913 struct nfs_page *req)
915 struct nfs_page *subreq;
916 unsigned int bytes_left = 0;
917 unsigned int offset, pgbase;
919 nfs_page_group_lock(req);
922 bytes_left = subreq->wb_bytes;
923 offset = subreq->wb_offset;
924 pgbase = subreq->wb_pgbase;
927 if (!nfs_pageio_do_add_request(desc, subreq)) {
928 /* make sure pg_test call(s) did nothing */
929 WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
930 WARN_ON_ONCE(subreq->wb_offset != offset);
931 WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
933 nfs_page_group_unlock(req);
935 nfs_pageio_doio(desc);
936 if (desc->pg_error < 0)
938 if (desc->pg_recoalesce)
940 /* retry add_request for this subreq */
941 nfs_page_group_lock(req);
945 /* check for buggy pg_test call(s) */
946 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
947 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
948 WARN_ON_ONCE(subreq->wb_bytes == 0);
950 bytes_left -= subreq->wb_bytes;
951 offset += subreq->wb_bytes;
952 pgbase += subreq->wb_bytes;
955 subreq = nfs_create_request(req->wb_context,
957 subreq, pgbase, bytes_left);
960 nfs_lock_request(subreq);
961 subreq->wb_offset = offset;
962 subreq->wb_index = req->wb_index;
964 } while (bytes_left > 0);
966 nfs_page_group_unlock(req);
969 desc->pg_error = PTR_ERR(subreq);
970 nfs_page_group_unlock(req);
974 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
979 list_splice_init(&desc->pg_list, &head);
980 desc->pg_bytes_written -= desc->pg_count;
983 desc->pg_recoalesce = 0;
986 while (!list_empty(&head)) {
987 struct nfs_page *req;
989 req = list_first_entry(&head, struct nfs_page, wb_list);
990 nfs_list_remove_request(req);
991 if (__nfs_pageio_add_request(desc, req))
993 if (desc->pg_error < 0)
997 } while (desc->pg_recoalesce);
1001 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1002 struct nfs_page *req)
1007 ret = __nfs_pageio_add_request(desc, req);
1010 if (desc->pg_error < 0)
1012 ret = nfs_do_recoalesce(desc);
1016 EXPORT_SYMBOL_GPL(nfs_pageio_add_request);
1019 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
1020 * @desc: pointer to io descriptor
1022 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1025 nfs_pageio_doio(desc);
1026 if (!desc->pg_recoalesce)
1028 if (!nfs_do_recoalesce(desc))
1032 EXPORT_SYMBOL_GPL(nfs_pageio_complete);
1035 * nfs_pageio_cond_complete - Conditional I/O completion
1036 * @desc: pointer to io descriptor
1037 * @index: page index
1039 * It is important to ensure that processes don't try to take locks
1040 * on non-contiguous ranges of pages as that might deadlock. This
1041 * function should be called before attempting to wait on a locked
1042 * nfs_page. It will complete the I/O if the page index 'index'
1043 * is not contiguous with the existing list of pages in 'desc'.
1045 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1047 if (!list_empty(&desc->pg_list)) {
1048 struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
1049 if (index != prev->wb_index + 1)
1050 nfs_pageio_complete(desc);
1054 int __init nfs_init_nfspagecache(void)
1056 nfs_page_cachep = kmem_cache_create("nfs_page",
1057 sizeof(struct nfs_page),
1058 0, SLAB_HWCACHE_ALIGN,
1060 if (nfs_page_cachep == NULL)
1066 void nfs_destroy_nfspagecache(void)
1068 kmem_cache_destroy(nfs_page_cachep);
1071 static const struct rpc_call_ops nfs_pgio_common_ops = {
1072 .rpc_call_prepare = nfs_pgio_prepare,
1073 .rpc_call_done = nfs_pgio_result,
1074 .rpc_release = nfs_pgio_release,
1077 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1078 .pg_test = nfs_generic_pg_test,
1079 .pg_doio = nfs_generic_pg_pgios,