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(&q.key);
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);
140 * nfs_page_group_lock - lock the head of the page group
141 * @req - request in group that is to be locked
142 * @nonblock - if true don't block waiting for lock
144 * this lock must be held if modifying the page group list
146 * returns result from wait_on_bit_lock: 0 on success, < 0 on error
149 nfs_page_group_lock(struct nfs_page *req, bool nonblock)
151 struct nfs_page *head = req->wb_head;
154 WARN_ON_ONCE(head != head->wb_head);
157 ret = wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
158 TASK_UNINTERRUPTIBLE);
159 } while (!nonblock && ret != 0);
161 WARN_ON_ONCE(ret > 0);
166 * nfs_page_group_unlock - unlock the head of the page group
167 * @req - request in group that is to be unlocked
170 nfs_page_group_unlock(struct nfs_page *req)
172 struct nfs_page *head = req->wb_head;
174 WARN_ON_ONCE(head != head->wb_head);
176 smp_mb__before_atomic();
177 clear_bit(PG_HEADLOCK, &head->wb_flags);
178 smp_mb__after_atomic();
179 wake_up_bit(&head->wb_flags, PG_HEADLOCK);
183 * nfs_page_group_sync_on_bit_locked
185 * must be called with page group lock held
188 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
190 struct nfs_page *head = req->wb_head;
191 struct nfs_page *tmp;
193 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
194 WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
196 tmp = req->wb_this_page;
198 if (!test_bit(bit, &tmp->wb_flags))
200 tmp = tmp->wb_this_page;
203 /* true! reset all bits */
206 clear_bit(bit, &tmp->wb_flags);
207 tmp = tmp->wb_this_page;
208 } while (tmp != req);
214 * nfs_page_group_sync_on_bit - set bit on current request, but only
215 * return true if the bit is set for all requests in page group
216 * @req - request in page group
217 * @bit - PG_* bit that is used to sync page group
219 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
223 nfs_page_group_lock(req, false);
224 ret = nfs_page_group_sync_on_bit_locked(req, bit);
225 nfs_page_group_unlock(req);
231 * nfs_page_group_init - Initialize the page group linkage for @req
232 * @req - a new nfs request
233 * @prev - the previous request in page group, or NULL if @req is the first
234 * or only request in the group (the head).
237 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
239 WARN_ON_ONCE(prev == req);
244 req->wb_this_page = req;
247 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
248 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
249 req->wb_head = prev->wb_head;
250 req->wb_this_page = prev->wb_this_page;
251 prev->wb_this_page = req;
253 /* All subrequests take a ref on the head request until
254 * nfs_page_group_destroy is called */
255 kref_get(&req->wb_head->wb_kref);
257 /* grab extra ref if head request has extra ref from
258 * the write/commit path to handle handoff between write
259 * and commit lists */
260 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
261 set_bit(PG_INODE_REF, &req->wb_flags);
262 kref_get(&req->wb_kref);
268 * nfs_page_group_destroy - sync the destruction of page groups
269 * @req - request that no longer needs the page group
271 * releases the page group reference from each member once all
272 * members have called this function.
275 nfs_page_group_destroy(struct kref *kref)
277 struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
278 struct nfs_page *tmp, *next;
280 /* subrequests must release the ref on the head request */
281 if (req->wb_head != req)
282 nfs_release_request(req->wb_head);
284 if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
289 next = tmp->wb_this_page;
290 /* unlink and free */
291 tmp->wb_this_page = tmp;
293 nfs_free_request(tmp);
295 } while (tmp != req);
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
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.
311 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
312 struct nfs_page *last, unsigned int offset,
315 struct nfs_page *req;
316 struct nfs_lock_context *l_ctx;
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();
323 return ERR_PTR(-ENOMEM);
325 /* get lock context early so we can deal with alloc failures */
326 l_ctx = nfs_get_lock_context(ctx);
329 return ERR_CAST(l_ctx);
331 req->wb_lock_context = l_ctx;
332 nfs_iocounter_inc(&l_ctx->io_count);
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. */
338 req->wb_index = page_file_index(page);
339 page_cache_get(page);
340 req->wb_offset = offset;
341 req->wb_pgbase = offset;
342 req->wb_bytes = count;
343 req->wb_context = get_nfs_open_context(ctx);
344 kref_init(&req->wb_kref);
345 nfs_page_group_init(req, last);
350 * nfs_unlock_request - Unlock request and wake up sleepers.
353 void nfs_unlock_request(struct nfs_page *req)
355 if (!NFS_WBACK_BUSY(req)) {
356 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
359 smp_mb__before_atomic();
360 clear_bit(PG_BUSY, &req->wb_flags);
361 smp_mb__after_atomic();
362 wake_up_bit(&req->wb_flags, PG_BUSY);
366 * nfs_unlock_and_release_request - Unlock request and release the nfs_page
369 void nfs_unlock_and_release_request(struct nfs_page *req)
371 nfs_unlock_request(req);
372 nfs_release_request(req);
376 * nfs_clear_request - Free up all resources allocated to the request
379 * Release page and open context resources associated with a read/write
380 * request after it has completed.
382 static void nfs_clear_request(struct nfs_page *req)
384 struct page *page = req->wb_page;
385 struct nfs_open_context *ctx = req->wb_context;
386 struct nfs_lock_context *l_ctx = req->wb_lock_context;
389 page_cache_release(page);
393 nfs_iocounter_dec(&l_ctx->io_count);
394 nfs_put_lock_context(l_ctx);
395 req->wb_lock_context = NULL;
398 put_nfs_open_context(ctx);
399 req->wb_context = NULL;
404 * nfs_release_request - Release the count on an NFS read/write request
405 * @req: request to release
407 * Note: Should never be called with the spinlock held!
409 void nfs_free_request(struct nfs_page *req)
411 WARN_ON_ONCE(req->wb_this_page != req);
413 /* extra debug: make sure no sync bits are still set */
414 WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
415 WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
416 WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
417 WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
418 WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
420 /* Release struct file and open context */
421 nfs_clear_request(req);
425 void nfs_release_request(struct nfs_page *req)
427 kref_put(&req->wb_kref, nfs_page_group_destroy);
431 * nfs_wait_on_request - Wait for a request to complete.
432 * @req: request to wait upon.
434 * Interruptible by fatal signals only.
435 * The user is responsible for holding a count on the request.
438 nfs_wait_on_request(struct nfs_page *req)
440 return wait_on_bit_io(&req->wb_flags, PG_BUSY,
441 TASK_UNINTERRUPTIBLE);
445 * nfs_generic_pg_test - determine if requests can be coalesced
446 * @desc: pointer to descriptor
447 * @prev: previous request in desc, or NULL
450 * Returns zero if @req can be coalesced into @desc, otherwise it returns
451 * the size of the request.
453 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
454 struct nfs_page *prev, struct nfs_page *req)
456 if (desc->pg_count > desc->pg_bsize) {
457 /* should never happen */
462 return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
464 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
466 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
468 struct nfs_pgio_header *hdr = ops->rw_alloc_header();
471 INIT_LIST_HEAD(&hdr->pages);
472 spin_lock_init(&hdr->lock);
477 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
480 * nfs_pgio_header_free - Free a read or write header
481 * @hdr: The header to free
483 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
485 hdr->rw_ops->rw_free_header(hdr);
487 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
490 * nfs_pgio_data_destroy - make @hdr suitable for reuse
492 * Frees memory and releases refs from nfs_generic_pgio, so that it may
495 * @hdr: A header that has had nfs_generic_pgio called
497 void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
499 put_nfs_open_context(hdr->args.context);
500 if (hdr->page_array.pagevec != hdr->page_array.page_array)
501 kfree(hdr->page_array.pagevec);
503 EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
506 * nfs_pgio_rpcsetup - Set up arguments for a pageio call
507 * @hdr: The pageio hdr
508 * @count: Number of bytes to read
509 * @offset: Initial offset
510 * @how: How to commit data (writes only)
511 * @cinfo: Commit information for the call (writes only)
513 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
514 unsigned int count, unsigned int offset,
515 int how, struct nfs_commit_info *cinfo)
517 struct nfs_page *req = hdr->req;
519 /* Set up the RPC argument and reply structs
520 * NB: take care not to mess about with hdr->commit et al. */
522 hdr->args.fh = NFS_FH(hdr->inode);
523 hdr->args.offset = req_offset(req) + offset;
524 /* pnfs_set_layoutcommit needs this */
525 hdr->mds_offset = hdr->args.offset;
526 hdr->args.pgbase = req->wb_pgbase + offset;
527 hdr->args.pages = hdr->page_array.pagevec;
528 hdr->args.count = count;
529 hdr->args.context = get_nfs_open_context(req->wb_context);
530 hdr->args.lock_context = req->wb_lock_context;
531 hdr->args.stable = NFS_UNSTABLE;
532 switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
535 case FLUSH_COND_STABLE:
536 if (nfs_reqs_to_commit(cinfo))
539 hdr->args.stable = NFS_FILE_SYNC;
542 hdr->res.fattr = &hdr->fattr;
543 hdr->res.count = count;
545 hdr->res.verf = &hdr->verf;
546 nfs_fattr_init(&hdr->fattr);
550 * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
551 * @task: The current task
552 * @calldata: pageio header to prepare
554 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
556 struct nfs_pgio_header *hdr = calldata;
558 err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
563 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
564 const struct rpc_call_ops *call_ops, int how, int flags)
566 struct rpc_task *task;
567 struct rpc_message msg = {
568 .rpc_argp = &hdr->args,
569 .rpc_resp = &hdr->res,
570 .rpc_cred = hdr->cred,
572 struct rpc_task_setup task_setup_data = {
576 .callback_ops = call_ops,
577 .callback_data = hdr,
578 .workqueue = nfsiod_workqueue,
579 .flags = RPC_TASK_ASYNC | flags,
583 hdr->rw_ops->rw_initiate(hdr, &msg, &task_setup_data, how);
585 dprintk("NFS: %5u initiated pgio call "
586 "(req %s/%llu, %u bytes @ offset %llu)\n",
588 hdr->inode->i_sb->s_id,
589 (unsigned long long)NFS_FILEID(hdr->inode),
591 (unsigned long long)hdr->args.offset);
593 task = rpc_run_task(&task_setup_data);
598 if (how & FLUSH_SYNC) {
599 ret = rpc_wait_for_completion_task(task);
601 ret = task->tk_status;
607 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
610 * nfs_pgio_error - Clean up from a pageio error
611 * @desc: IO descriptor
612 * @hdr: pageio header
614 static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
615 struct nfs_pgio_header *hdr)
617 set_bit(NFS_IOHDR_REDO, &hdr->flags);
618 nfs_pgio_data_destroy(hdr);
619 hdr->completion_ops->completion(hdr);
620 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
625 * nfs_pgio_release - Release pageio data
626 * @calldata: The pageio header to release
628 static void nfs_pgio_release(void *calldata)
630 struct nfs_pgio_header *hdr = calldata;
631 if (hdr->rw_ops->rw_release)
632 hdr->rw_ops->rw_release(hdr);
633 nfs_pgio_data_destroy(hdr);
634 hdr->completion_ops->completion(hdr);
638 * nfs_pageio_init - initialise a page io descriptor
639 * @desc: pointer to descriptor
640 * @inode: pointer to inode
641 * @doio: pointer to io function
642 * @bsize: io block size
643 * @io_flags: extra parameters for the io function
645 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
647 const struct nfs_pageio_ops *pg_ops,
648 const struct nfs_pgio_completion_ops *compl_ops,
649 const struct nfs_rw_ops *rw_ops,
653 INIT_LIST_HEAD(&desc->pg_list);
654 desc->pg_bytes_written = 0;
656 desc->pg_bsize = bsize;
659 desc->pg_recoalesce = 0;
660 desc->pg_inode = inode;
661 desc->pg_ops = pg_ops;
662 desc->pg_completion_ops = compl_ops;
663 desc->pg_rw_ops = rw_ops;
664 desc->pg_ioflags = io_flags;
666 desc->pg_lseg = NULL;
667 desc->pg_dreq = NULL;
668 desc->pg_layout_private = NULL;
670 EXPORT_SYMBOL_GPL(nfs_pageio_init);
673 * nfs_pgio_result - Basic pageio error handling
674 * @task: The task that ran
675 * @calldata: Pageio header to check
677 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
679 struct nfs_pgio_header *hdr = calldata;
680 struct inode *inode = hdr->inode;
682 dprintk("NFS: %s: %5u, (status %d)\n", __func__,
683 task->tk_pid, task->tk_status);
685 if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
687 if (task->tk_status < 0)
688 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
690 hdr->rw_ops->rw_result(task, hdr);
694 * Create an RPC task for the given read or write request and kick it.
695 * The page must have been locked by the caller.
697 * It may happen that the page we're passed is not marked dirty.
698 * This is the case if nfs_updatepage detects a conflicting request
699 * that has been written but not committed.
701 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
702 struct nfs_pgio_header *hdr)
704 struct nfs_page *req;
706 struct list_head *head = &desc->pg_list;
707 struct nfs_commit_info cinfo;
708 unsigned int pagecount;
710 pagecount = nfs_page_array_len(desc->pg_base, desc->pg_count);
711 if (!nfs_pgarray_set(&hdr->page_array, pagecount))
712 return nfs_pgio_error(desc, hdr);
714 nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
715 pages = hdr->page_array.pagevec;
716 while (!list_empty(head)) {
717 req = nfs_list_entry(head->next);
718 nfs_list_remove_request(req);
719 nfs_list_add_request(req, &hdr->pages);
720 *pages++ = req->wb_page;
723 if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
724 (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
725 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
727 /* Set up the argument struct */
728 nfs_pgio_rpcsetup(hdr, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
729 desc->pg_rpc_callops = &nfs_pgio_common_ops;
732 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
734 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
736 struct nfs_pgio_header *hdr;
739 hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
741 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
744 nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
745 ret = nfs_generic_pgio(desc, hdr);
747 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
748 hdr, desc->pg_rpc_callops,
749 desc->pg_ioflags, 0);
753 static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
754 const struct nfs_open_context *ctx2)
756 return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
759 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
760 const struct nfs_lock_context *l2)
762 return l1->lockowner.l_owner == l2->lockowner.l_owner
763 && l1->lockowner.l_pid == l2->lockowner.l_pid;
767 * nfs_can_coalesce_requests - test two requests for compatibility
768 * @prev: pointer to nfs_page
769 * @req: pointer to nfs_page
771 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
772 * page data area they describe is contiguous, and that their RPC
773 * credentials, NFSv4 open state, and lockowners are the same.
775 * Return 'true' if this is the case, else return 'false'.
777 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
778 struct nfs_page *req,
779 struct nfs_pageio_descriptor *pgio)
784 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
786 if (req->wb_context->dentry->d_inode->i_flock != NULL &&
787 !nfs_match_lock_context(req->wb_lock_context,
788 prev->wb_lock_context))
790 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
793 size = pgio->pg_ops->pg_test(pgio, prev, req);
794 WARN_ON_ONCE(size > req->wb_bytes);
795 if (size && size < req->wb_bytes)
796 req->wb_bytes = size;
801 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
802 * @desc: destination io descriptor
805 * Returns true if the request 'req' was successfully coalesced into the
806 * existing list of pages 'desc'.
808 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
809 struct nfs_page *req)
811 struct nfs_page *prev = NULL;
812 if (desc->pg_count != 0) {
813 prev = nfs_list_entry(desc->pg_list.prev);
815 if (desc->pg_ops->pg_init)
816 desc->pg_ops->pg_init(desc, req);
817 desc->pg_base = req->wb_pgbase;
819 if (!nfs_can_coalesce_requests(prev, req, desc))
821 nfs_list_remove_request(req);
822 nfs_list_add_request(req, &desc->pg_list);
823 desc->pg_count += req->wb_bytes;
828 * Helper for nfs_pageio_add_request and nfs_pageio_complete
830 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
832 if (!list_empty(&desc->pg_list)) {
833 int error = desc->pg_ops->pg_doio(desc);
835 desc->pg_error = error;
837 desc->pg_bytes_written += desc->pg_count;
839 if (list_empty(&desc->pg_list)) {
846 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
847 * @desc: destination io descriptor
850 * This may split a request into subrequests which are all part of the
853 * Returns true if the request 'req' was successfully coalesced into the
854 * existing list of pages 'desc'.
856 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
857 struct nfs_page *req)
859 struct nfs_page *subreq;
860 unsigned int bytes_left = 0;
861 unsigned int offset, pgbase;
864 ret = nfs_page_group_lock(req, true);
866 desc->pg_error = ret;
871 bytes_left = subreq->wb_bytes;
872 offset = subreq->wb_offset;
873 pgbase = subreq->wb_pgbase;
876 if (!nfs_pageio_do_add_request(desc, subreq)) {
877 /* make sure pg_test call(s) did nothing */
878 WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
879 WARN_ON_ONCE(subreq->wb_offset != offset);
880 WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
882 nfs_page_group_unlock(req);
884 nfs_pageio_doio(desc);
885 if (desc->pg_error < 0)
887 if (desc->pg_recoalesce)
889 /* retry add_request for this subreq */
890 ret = nfs_page_group_lock(req, true);
892 desc->pg_error = ret;
898 /* check for buggy pg_test call(s) */
899 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
900 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
901 WARN_ON_ONCE(subreq->wb_bytes == 0);
903 bytes_left -= subreq->wb_bytes;
904 offset += subreq->wb_bytes;
905 pgbase += subreq->wb_bytes;
908 subreq = nfs_create_request(req->wb_context,
910 subreq, pgbase, bytes_left);
913 nfs_lock_request(subreq);
914 subreq->wb_offset = offset;
915 subreq->wb_index = req->wb_index;
917 } while (bytes_left > 0);
919 nfs_page_group_unlock(req);
922 desc->pg_error = PTR_ERR(subreq);
923 nfs_page_group_unlock(req);
927 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
932 list_splice_init(&desc->pg_list, &head);
933 desc->pg_bytes_written -= desc->pg_count;
936 desc->pg_recoalesce = 0;
939 while (!list_empty(&head)) {
940 struct nfs_page *req;
942 req = list_first_entry(&head, struct nfs_page, wb_list);
943 nfs_list_remove_request(req);
944 if (__nfs_pageio_add_request(desc, req))
946 if (desc->pg_error < 0)
950 } while (desc->pg_recoalesce);
954 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
955 struct nfs_page *req)
960 ret = __nfs_pageio_add_request(desc, req);
963 if (desc->pg_error < 0)
965 ret = nfs_do_recoalesce(desc);
971 * nfs_pageio_resend - Transfer requests to new descriptor and resend
972 * @hdr - the pgio header to move request from
973 * @desc - the pageio descriptor to add requests to
975 * Try to move each request (nfs_page) from @hdr to @desc then attempt
978 * Returns 0 on success and < 0 on error.
980 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
981 struct nfs_pgio_header *hdr)
985 desc->pg_dreq = hdr->dreq;
986 while (!list_empty(&hdr->pages)) {
987 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
989 nfs_list_remove_request(req);
990 if (!nfs_pageio_add_request(desc, req))
991 nfs_list_add_request(req, &failed);
993 nfs_pageio_complete(desc);
994 if (!list_empty(&failed)) {
995 list_move(&failed, &hdr->pages);
1000 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1003 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
1004 * @desc: pointer to io descriptor
1006 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1009 nfs_pageio_doio(desc);
1010 if (!desc->pg_recoalesce)
1012 if (!nfs_do_recoalesce(desc))
1018 * nfs_pageio_cond_complete - Conditional I/O completion
1019 * @desc: pointer to io descriptor
1020 * @index: page index
1022 * It is important to ensure that processes don't try to take locks
1023 * on non-contiguous ranges of pages as that might deadlock. This
1024 * function should be called before attempting to wait on a locked
1025 * nfs_page. It will complete the I/O if the page index 'index'
1026 * is not contiguous with the existing list of pages in 'desc'.
1028 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1030 if (!list_empty(&desc->pg_list)) {
1031 struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
1032 if (index != prev->wb_index + 1)
1033 nfs_pageio_complete(desc);
1037 int __init nfs_init_nfspagecache(void)
1039 nfs_page_cachep = kmem_cache_create("nfs_page",
1040 sizeof(struct nfs_page),
1041 0, SLAB_HWCACHE_ALIGN,
1043 if (nfs_page_cachep == NULL)
1049 void nfs_destroy_nfspagecache(void)
1051 kmem_cache_destroy(nfs_page_cachep);
1054 static const struct rpc_call_ops nfs_pgio_common_ops = {
1055 .rpc_call_prepare = nfs_pgio_prepare,
1056 .rpc_call_done = nfs_pgio_result,
1057 .rpc_release = nfs_pgio_release,
1060 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1061 .pg_test = nfs_generic_pg_test,
1062 .pg_doio = nfs_generic_pg_pgios,