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
143 * this lock must be held if modifying the page group list
145 * returns result from wait_on_bit_lock: 0 on success, < 0 on error
148 nfs_page_group_lock(struct nfs_page *req, bool wait)
150 struct nfs_page *head = req->wb_head;
153 WARN_ON_ONCE(head != head->wb_head);
156 ret = wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
157 TASK_UNINTERRUPTIBLE);
158 } while (wait && ret != 0);
160 WARN_ON_ONCE(ret > 0);
165 * nfs_page_group_unlock - unlock the head of the page group
166 * @req - request in group that is to be unlocked
169 nfs_page_group_unlock(struct nfs_page *req)
171 struct nfs_page *head = req->wb_head;
173 WARN_ON_ONCE(head != head->wb_head);
175 smp_mb__before_atomic();
176 clear_bit(PG_HEADLOCK, &head->wb_flags);
177 smp_mb__after_atomic();
178 wake_up_bit(&head->wb_flags, PG_HEADLOCK);
182 * nfs_page_group_sync_on_bit_locked
184 * must be called with page group lock held
187 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
189 struct nfs_page *head = req->wb_head;
190 struct nfs_page *tmp;
192 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
193 WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
195 tmp = req->wb_this_page;
197 if (!test_bit(bit, &tmp->wb_flags))
199 tmp = tmp->wb_this_page;
202 /* true! reset all bits */
205 clear_bit(bit, &tmp->wb_flags);
206 tmp = tmp->wb_this_page;
207 } while (tmp != req);
213 * nfs_page_group_sync_on_bit - set bit on current request, but only
214 * return true if the bit is set for all requests in page group
215 * @req - request in page group
216 * @bit - PG_* bit that is used to sync page group
218 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
222 nfs_page_group_lock(req, true);
223 ret = nfs_page_group_sync_on_bit_locked(req, bit);
224 nfs_page_group_unlock(req);
230 * nfs_page_group_init - Initialize the page group linkage for @req
231 * @req - a new nfs request
232 * @prev - the previous request in page group, or NULL if @req is the first
233 * or only request in the group (the head).
236 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
238 WARN_ON_ONCE(prev == req);
243 req->wb_this_page = req;
246 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
247 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
248 req->wb_head = prev->wb_head;
249 req->wb_this_page = prev->wb_this_page;
250 prev->wb_this_page = req;
252 /* All subrequests take a ref on the head request until
253 * nfs_page_group_destroy is called */
254 kref_get(&req->wb_head->wb_kref);
256 /* grab extra ref if head request has extra ref from
257 * the write/commit path to handle handoff between write
258 * and commit lists */
259 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
260 set_bit(PG_INODE_REF, &req->wb_flags);
261 kref_get(&req->wb_kref);
267 * nfs_page_group_destroy - sync the destruction of page groups
268 * @req - request that no longer needs the page group
270 * releases the page group reference from each member once all
271 * members have called this function.
274 nfs_page_group_destroy(struct kref *kref)
276 struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
277 struct nfs_page *tmp, *next;
279 /* subrequests must release the ref on the head request */
280 if (req->wb_head != req)
281 nfs_release_request(req->wb_head);
283 if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
288 next = tmp->wb_this_page;
289 /* unlink and free */
290 tmp->wb_this_page = tmp;
292 nfs_free_request(tmp);
294 } while (tmp != req);
298 * nfs_create_request - Create an NFS read/write request.
299 * @ctx: open context to use
300 * @page: page to write
301 * @last: last nfs request created for this page group or NULL if head
302 * @offset: starting offset within the page for the write
303 * @count: number of bytes to read/write
305 * The page must be locked by the caller. This makes sure we never
306 * create two different requests for the same page.
307 * User should ensure it is safe to sleep in this function.
310 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
311 struct nfs_page *last, unsigned int offset,
314 struct nfs_page *req;
315 struct nfs_lock_context *l_ctx;
317 if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
318 return ERR_PTR(-EBADF);
319 /* try to allocate the request struct */
320 req = nfs_page_alloc();
322 return ERR_PTR(-ENOMEM);
324 /* get lock context early so we can deal with alloc failures */
325 l_ctx = nfs_get_lock_context(ctx);
328 return ERR_CAST(l_ctx);
330 req->wb_lock_context = l_ctx;
331 nfs_iocounter_inc(&l_ctx->io_count);
333 /* Initialize the request struct. Initially, we assume a
334 * long write-back delay. This will be adjusted in
335 * update_nfs_request below if the region is not locked. */
337 req->wb_index = page_file_index(page);
338 page_cache_get(page);
339 req->wb_offset = offset;
340 req->wb_pgbase = offset;
341 req->wb_bytes = count;
342 req->wb_context = get_nfs_open_context(ctx);
343 kref_init(&req->wb_kref);
344 nfs_page_group_init(req, last);
349 * nfs_unlock_request - Unlock request and wake up sleepers.
352 void nfs_unlock_request(struct nfs_page *req)
354 if (!NFS_WBACK_BUSY(req)) {
355 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
358 smp_mb__before_atomic();
359 clear_bit(PG_BUSY, &req->wb_flags);
360 smp_mb__after_atomic();
361 wake_up_bit(&req->wb_flags, PG_BUSY);
365 * nfs_unlock_and_release_request - Unlock request and release the nfs_page
368 void nfs_unlock_and_release_request(struct nfs_page *req)
370 nfs_unlock_request(req);
371 nfs_release_request(req);
375 * nfs_clear_request - Free up all resources allocated to the request
378 * Release page and open context resources associated with a read/write
379 * request after it has completed.
381 static void nfs_clear_request(struct nfs_page *req)
383 struct page *page = req->wb_page;
384 struct nfs_open_context *ctx = req->wb_context;
385 struct nfs_lock_context *l_ctx = req->wb_lock_context;
388 page_cache_release(page);
392 nfs_iocounter_dec(&l_ctx->io_count);
393 nfs_put_lock_context(l_ctx);
394 req->wb_lock_context = NULL;
397 put_nfs_open_context(ctx);
398 req->wb_context = NULL;
403 * nfs_release_request - Release the count on an NFS read/write request
404 * @req: request to release
406 * Note: Should never be called with the spinlock held!
408 void nfs_free_request(struct nfs_page *req)
410 WARN_ON_ONCE(req->wb_this_page != req);
412 /* extra debug: make sure no sync bits are still set */
413 WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
414 WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
415 WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
416 WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
417 WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
419 /* Release struct file and open context */
420 nfs_clear_request(req);
424 void nfs_release_request(struct nfs_page *req)
426 kref_put(&req->wb_kref, nfs_page_group_destroy);
430 * nfs_wait_on_request - Wait for a request to complete.
431 * @req: request to wait upon.
433 * Interruptible by fatal signals only.
434 * The user is responsible for holding a count on the request.
437 nfs_wait_on_request(struct nfs_page *req)
439 return wait_on_bit_io(&req->wb_flags, PG_BUSY,
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 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
467 struct nfs_pgio_header *hdr = ops->rw_alloc_header();
470 INIT_LIST_HEAD(&hdr->pages);
471 spin_lock_init(&hdr->lock);
476 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
479 * nfs_pgio_header_free - Free a read or write header
480 * @hdr: The header to free
482 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
484 hdr->rw_ops->rw_free_header(hdr);
486 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
489 * nfs_pgio_data_destroy - make @hdr suitable for reuse
491 * Frees memory and releases refs from nfs_generic_pgio, so that it may
494 * @hdr: A header that has had nfs_generic_pgio called
496 void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
498 put_nfs_open_context(hdr->args.context);
499 if (hdr->page_array.pagevec != hdr->page_array.page_array)
500 kfree(hdr->page_array.pagevec);
502 EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
505 * nfs_pgio_rpcsetup - Set up arguments for a pageio call
506 * @hdr: The pageio hdr
507 * @count: Number of bytes to read
508 * @offset: Initial offset
509 * @how: How to commit data (writes only)
510 * @cinfo: Commit information for the call (writes only)
512 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
513 unsigned int count, unsigned int offset,
514 int how, struct nfs_commit_info *cinfo)
516 struct nfs_page *req = hdr->req;
518 /* Set up the RPC argument and reply structs
519 * NB: take care not to mess about with hdr->commit et al. */
521 hdr->args.fh = NFS_FH(hdr->inode);
522 hdr->args.offset = req_offset(req) + offset;
523 /* pnfs_set_layoutcommit needs this */
524 hdr->mds_offset = hdr->args.offset;
525 hdr->args.pgbase = req->wb_pgbase + offset;
526 hdr->args.pages = hdr->page_array.pagevec;
527 hdr->args.count = count;
528 hdr->args.context = get_nfs_open_context(req->wb_context);
529 hdr->args.lock_context = req->wb_lock_context;
530 hdr->args.stable = NFS_UNSTABLE;
531 switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
534 case FLUSH_COND_STABLE:
535 if (nfs_reqs_to_commit(cinfo))
538 hdr->args.stable = NFS_FILE_SYNC;
541 hdr->res.fattr = &hdr->fattr;
542 hdr->res.count = count;
544 hdr->res.verf = &hdr->verf;
545 nfs_fattr_init(&hdr->fattr);
549 * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
550 * @task: The current task
551 * @calldata: pageio header to prepare
553 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
555 struct nfs_pgio_header *hdr = calldata;
557 err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
562 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
563 const struct rpc_call_ops *call_ops, int how, int flags)
565 struct rpc_task *task;
566 struct rpc_message msg = {
567 .rpc_argp = &hdr->args,
568 .rpc_resp = &hdr->res,
569 .rpc_cred = hdr->cred,
571 struct rpc_task_setup task_setup_data = {
575 .callback_ops = call_ops,
576 .callback_data = hdr,
577 .workqueue = nfsiod_workqueue,
578 .flags = RPC_TASK_ASYNC | flags,
582 hdr->rw_ops->rw_initiate(hdr, &msg, &task_setup_data, how);
584 dprintk("NFS: %5u initiated pgio call "
585 "(req %s/%llu, %u bytes @ offset %llu)\n",
587 hdr->inode->i_sb->s_id,
588 (unsigned long long)NFS_FILEID(hdr->inode),
590 (unsigned long long)hdr->args.offset);
592 task = rpc_run_task(&task_setup_data);
597 if (how & FLUSH_SYNC) {
598 ret = rpc_wait_for_completion_task(task);
600 ret = task->tk_status;
606 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
609 * nfs_pgio_error - Clean up from a pageio error
610 * @desc: IO descriptor
611 * @hdr: pageio header
613 static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
614 struct nfs_pgio_header *hdr)
616 set_bit(NFS_IOHDR_REDO, &hdr->flags);
617 nfs_pgio_data_destroy(hdr);
618 hdr->completion_ops->completion(hdr);
619 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
624 * nfs_pgio_release - Release pageio data
625 * @calldata: The pageio header to release
627 static void nfs_pgio_release(void *calldata)
629 struct nfs_pgio_header *hdr = calldata;
630 if (hdr->rw_ops->rw_release)
631 hdr->rw_ops->rw_release(hdr);
632 nfs_pgio_data_destroy(hdr);
633 hdr->completion_ops->completion(hdr);
637 * nfs_pageio_init - initialise a page io descriptor
638 * @desc: pointer to descriptor
639 * @inode: pointer to inode
640 * @doio: pointer to io function
641 * @bsize: io block size
642 * @io_flags: extra parameters for the io function
644 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
646 const struct nfs_pageio_ops *pg_ops,
647 const struct nfs_pgio_completion_ops *compl_ops,
648 const struct nfs_rw_ops *rw_ops,
652 INIT_LIST_HEAD(&desc->pg_list);
653 desc->pg_bytes_written = 0;
655 desc->pg_bsize = bsize;
658 desc->pg_recoalesce = 0;
659 desc->pg_inode = inode;
660 desc->pg_ops = pg_ops;
661 desc->pg_completion_ops = compl_ops;
662 desc->pg_rw_ops = rw_ops;
663 desc->pg_ioflags = io_flags;
665 desc->pg_lseg = NULL;
666 desc->pg_dreq = NULL;
667 desc->pg_layout_private = NULL;
669 EXPORT_SYMBOL_GPL(nfs_pageio_init);
672 * nfs_pgio_result - Basic pageio error handling
673 * @task: The task that ran
674 * @calldata: Pageio header to check
676 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
678 struct nfs_pgio_header *hdr = calldata;
679 struct inode *inode = hdr->inode;
681 dprintk("NFS: %s: %5u, (status %d)\n", __func__,
682 task->tk_pid, task->tk_status);
684 if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
686 if (task->tk_status < 0)
687 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
689 hdr->rw_ops->rw_result(task, hdr);
693 * Create an RPC task for the given read or write request and kick it.
694 * The page must have been locked by the caller.
696 * It may happen that the page we're passed is not marked dirty.
697 * This is the case if nfs_updatepage detects a conflicting request
698 * that has been written but not committed.
700 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
701 struct nfs_pgio_header *hdr)
703 struct nfs_page *req;
705 struct list_head *head = &desc->pg_list;
706 struct nfs_commit_info cinfo;
707 unsigned int pagecount;
709 pagecount = nfs_page_array_len(desc->pg_base, desc->pg_count);
710 if (!nfs_pgarray_set(&hdr->page_array, pagecount))
711 return nfs_pgio_error(desc, hdr);
713 nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
714 pages = hdr->page_array.pagevec;
715 while (!list_empty(head)) {
716 req = nfs_list_entry(head->next);
717 nfs_list_remove_request(req);
718 nfs_list_add_request(req, &hdr->pages);
719 *pages++ = req->wb_page;
722 if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
723 (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
724 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
726 /* Set up the argument struct */
727 nfs_pgio_rpcsetup(hdr, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
728 desc->pg_rpc_callops = &nfs_pgio_common_ops;
731 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
733 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
735 struct nfs_pgio_header *hdr;
738 hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
740 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
743 nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
744 ret = nfs_generic_pgio(desc, hdr);
746 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
747 hdr, desc->pg_rpc_callops,
748 desc->pg_ioflags, 0);
752 static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
753 const struct nfs_open_context *ctx2)
755 return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
758 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
759 const struct nfs_lock_context *l2)
761 return l1->lockowner.l_owner == l2->lockowner.l_owner
762 && l1->lockowner.l_pid == l2->lockowner.l_pid;
766 * nfs_can_coalesce_requests - test two requests for compatibility
767 * @prev: pointer to nfs_page
768 * @req: pointer to nfs_page
770 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
771 * page data area they describe is contiguous, and that their RPC
772 * credentials, NFSv4 open state, and lockowners are the same.
774 * Return 'true' if this is the case, else return 'false'.
776 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
777 struct nfs_page *req,
778 struct nfs_pageio_descriptor *pgio)
783 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
785 if (req->wb_context->dentry->d_inode->i_flock != NULL &&
786 !nfs_match_lock_context(req->wb_lock_context,
787 prev->wb_lock_context))
789 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
792 size = pgio->pg_ops->pg_test(pgio, prev, req);
793 WARN_ON_ONCE(size > req->wb_bytes);
794 if (size && size < req->wb_bytes)
795 req->wb_bytes = size;
800 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
801 * @desc: destination io descriptor
804 * Returns true if the request 'req' was successfully coalesced into the
805 * existing list of pages 'desc'.
807 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
808 struct nfs_page *req)
810 struct nfs_page *prev = NULL;
811 if (desc->pg_count != 0) {
812 prev = nfs_list_entry(desc->pg_list.prev);
814 if (desc->pg_ops->pg_init)
815 desc->pg_ops->pg_init(desc, req);
816 desc->pg_base = req->wb_pgbase;
818 if (!nfs_can_coalesce_requests(prev, req, desc))
820 nfs_list_remove_request(req);
821 nfs_list_add_request(req, &desc->pg_list);
822 desc->pg_count += req->wb_bytes;
827 * Helper for nfs_pageio_add_request and nfs_pageio_complete
829 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
831 if (!list_empty(&desc->pg_list)) {
832 int error = desc->pg_ops->pg_doio(desc);
834 desc->pg_error = error;
836 desc->pg_bytes_written += desc->pg_count;
838 if (list_empty(&desc->pg_list)) {
845 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
846 * @desc: destination io descriptor
849 * This may split a request into subrequests which are all part of the
852 * Returns true if the request 'req' was successfully coalesced into the
853 * existing list of pages 'desc'.
855 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
856 struct nfs_page *req)
858 struct nfs_page *subreq;
859 unsigned int bytes_left = 0;
860 unsigned int offset, pgbase;
863 ret = nfs_page_group_lock(req, false);
865 desc->pg_error = ret;
870 bytes_left = subreq->wb_bytes;
871 offset = subreq->wb_offset;
872 pgbase = subreq->wb_pgbase;
875 if (!nfs_pageio_do_add_request(desc, subreq)) {
876 /* make sure pg_test call(s) did nothing */
877 WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
878 WARN_ON_ONCE(subreq->wb_offset != offset);
879 WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
881 nfs_page_group_unlock(req);
883 nfs_pageio_doio(desc);
884 if (desc->pg_error < 0)
886 if (desc->pg_recoalesce)
888 /* retry add_request for this subreq */
889 ret = nfs_page_group_lock(req, false);
891 desc->pg_error = ret;
897 /* check for buggy pg_test call(s) */
898 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
899 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
900 WARN_ON_ONCE(subreq->wb_bytes == 0);
902 bytes_left -= subreq->wb_bytes;
903 offset += subreq->wb_bytes;
904 pgbase += subreq->wb_bytes;
907 subreq = nfs_create_request(req->wb_context,
909 subreq, pgbase, bytes_left);
912 nfs_lock_request(subreq);
913 subreq->wb_offset = offset;
914 subreq->wb_index = req->wb_index;
916 } while (bytes_left > 0);
918 nfs_page_group_unlock(req);
921 desc->pg_error = PTR_ERR(subreq);
922 nfs_page_group_unlock(req);
926 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
931 list_splice_init(&desc->pg_list, &head);
932 desc->pg_bytes_written -= desc->pg_count;
935 desc->pg_recoalesce = 0;
938 while (!list_empty(&head)) {
939 struct nfs_page *req;
941 req = list_first_entry(&head, struct nfs_page, wb_list);
942 nfs_list_remove_request(req);
943 if (__nfs_pageio_add_request(desc, req))
945 if (desc->pg_error < 0)
949 } while (desc->pg_recoalesce);
953 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
954 struct nfs_page *req)
959 ret = __nfs_pageio_add_request(desc, req);
962 if (desc->pg_error < 0)
964 ret = nfs_do_recoalesce(desc);
970 * nfs_pageio_resend - Transfer requests to new descriptor and resend
971 * @hdr - the pgio header to move request from
972 * @desc - the pageio descriptor to add requests to
974 * Try to move each request (nfs_page) from @hdr to @desc then attempt
977 * Returns 0 on success and < 0 on error.
979 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
980 struct nfs_pgio_header *hdr)
984 desc->pg_dreq = hdr->dreq;
985 while (!list_empty(&hdr->pages)) {
986 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
988 nfs_list_remove_request(req);
989 if (!nfs_pageio_add_request(desc, req))
990 nfs_list_add_request(req, &failed);
992 nfs_pageio_complete(desc);
993 if (!list_empty(&failed)) {
994 list_move(&failed, &hdr->pages);
999 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1002 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
1003 * @desc: pointer to io descriptor
1005 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1008 nfs_pageio_doio(desc);
1009 if (!desc->pg_recoalesce)
1011 if (!nfs_do_recoalesce(desc))
1017 * nfs_pageio_cond_complete - Conditional I/O completion
1018 * @desc: pointer to io descriptor
1019 * @index: page index
1021 * It is important to ensure that processes don't try to take locks
1022 * on non-contiguous ranges of pages as that might deadlock. This
1023 * function should be called before attempting to wait on a locked
1024 * nfs_page. It will complete the I/O if the page index 'index'
1025 * is not contiguous with the existing list of pages in 'desc'.
1027 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1029 if (!list_empty(&desc->pg_list)) {
1030 struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
1031 if (index != prev->wb_index + 1)
1032 nfs_pageio_complete(desc);
1036 int __init nfs_init_nfspagecache(void)
1038 nfs_page_cachep = kmem_cache_create("nfs_page",
1039 sizeof(struct nfs_page),
1040 0, SLAB_HWCACHE_ALIGN,
1042 if (nfs_page_cachep == NULL)
1048 void nfs_destroy_nfspagecache(void)
1050 kmem_cache_destroy(nfs_page_cachep);
1053 static const struct rpc_call_ops nfs_pgio_common_ops = {
1054 .rpc_call_prepare = nfs_pgio_prepare,
1055 .rpc_call_done = nfs_pgio_result,
1056 .rpc_release = nfs_pgio_release,
1059 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1060 .pg_test = nfs_generic_pg_test,
1061 .pg_doio = nfs_generic_pg_pgios,