6 * Partial copy of Linus' read cache modifications to fs/nfs/file.c
7 * modified for async RPC by okir@monad.swb.de
9 * We do an ugly hack here in order to return proper error codes to the
10 * user program when a read request failed: since generic_file_read
11 * only checks the return value of inode->i_op->readpage() which is always 0
12 * for async RPC, we set the error bit of the page to 1 when an error occurs,
13 * and make nfs_readpage transmit requests synchronously when encountering this.
14 * This is only a small problem, though, since we now retry all operations
15 * within the RPC code when root squashing is suspected.
18 #include <linux/time.h>
19 #include <linux/kernel.h>
20 #include <linux/errno.h>
21 #include <linux/fcntl.h>
22 #include <linux/stat.h>
24 #include <linux/slab.h>
25 #include <linux/pagemap.h>
26 #include <linux/sunrpc/clnt.h>
27 #include <linux/nfs_fs.h>
28 #include <linux/nfs_page.h>
29 #include <linux/smp_lock.h>
31 #include <asm/system.h>
35 #define NFSDBG_FACILITY NFSDBG_PAGECACHE
37 static int nfs_pagein_one(struct list_head *, struct inode *);
38 static const struct rpc_call_ops nfs_read_partial_ops;
39 static const struct rpc_call_ops nfs_read_full_ops;
41 static kmem_cache_t *nfs_rdata_cachep;
42 static mempool_t *nfs_rdata_mempool;
44 #define MIN_POOL_READ (32)
46 struct nfs_read_data *nfs_readdata_alloc(size_t len)
48 unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
49 struct nfs_read_data *p = mempool_alloc(nfs_rdata_mempool, SLAB_NOFS);
52 memset(p, 0, sizeof(*p));
53 INIT_LIST_HEAD(&p->pages);
54 p->npages = pagecount;
55 if (pagecount <= ARRAY_SIZE(p->page_array))
56 p->pagevec = p->page_array;
58 p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
60 mempool_free(p, nfs_rdata_mempool);
68 static void nfs_readdata_rcu_free(struct rcu_head *head)
70 struct nfs_read_data *p = container_of(head, struct nfs_read_data, task.u.tk_rcu);
71 if (p && (p->pagevec != &p->page_array[0]))
73 mempool_free(p, nfs_rdata_mempool);
76 static void nfs_readdata_free(struct nfs_read_data *rdata)
78 call_rcu_bh(&rdata->task.u.tk_rcu, nfs_readdata_rcu_free);
81 void nfs_readdata_release(void *data)
83 nfs_readdata_free(data);
87 unsigned int nfs_page_length(struct inode *inode, struct page *page)
89 loff_t i_size = i_size_read(inode);
94 idx = (i_size - 1) >> PAGE_CACHE_SHIFT;
95 if (page->index > idx)
97 if (page->index != idx)
98 return PAGE_CACHE_SIZE;
99 return 1 + ((i_size - 1) & (PAGE_CACHE_SIZE - 1));
103 int nfs_return_empty_page(struct page *page)
105 memclear_highpage_flush(page, 0, PAGE_CACHE_SIZE);
106 SetPageUptodate(page);
111 static void nfs_readpage_truncate_uninitialised_page(struct nfs_read_data *data)
113 unsigned int remainder = data->args.count - data->res.count;
114 unsigned int base = data->args.pgbase + data->res.count;
118 if (data->res.eof == 0 || remainder == 0)
121 * Note: "remainder" can never be negative, since we check for
122 * this in the XDR code.
124 pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
125 base &= ~PAGE_CACHE_MASK;
126 pglen = PAGE_CACHE_SIZE - base;
128 if (remainder <= pglen) {
129 memclear_highpage_flush(*pages, base, remainder);
132 memclear_highpage_flush(*pages, base, pglen);
135 pglen = PAGE_CACHE_SIZE;
141 * Read a page synchronously.
143 static int nfs_readpage_sync(struct nfs_open_context *ctx, struct inode *inode,
146 unsigned int rsize = NFS_SERVER(inode)->rsize;
147 unsigned int count = PAGE_CACHE_SIZE;
148 int result = -ENOMEM;
149 struct nfs_read_data *rdata;
151 rdata = nfs_readdata_alloc(count);
155 memset(rdata, 0, sizeof(*rdata));
156 rdata->flags = (IS_SWAPFILE(inode)? NFS_RPC_SWAPFLAGS : 0);
157 rdata->cred = ctx->cred;
158 rdata->inode = inode;
159 INIT_LIST_HEAD(&rdata->pages);
160 rdata->args.fh = NFS_FH(inode);
161 rdata->args.context = ctx;
162 rdata->args.pages = &page;
163 rdata->args.pgbase = 0UL;
164 rdata->args.count = rsize;
165 rdata->res.fattr = &rdata->fattr;
167 dprintk("NFS: nfs_readpage_sync(%p)\n", page);
170 * This works now because the socket layer never tries to DMA
171 * into this buffer directly.
175 rdata->args.count = count;
176 rdata->res.count = rdata->args.count;
177 rdata->args.offset = page_offset(page) + rdata->args.pgbase;
179 dprintk("NFS: nfs_proc_read(%s, (%s/%Ld), %Lu, %u)\n",
180 NFS_SERVER(inode)->nfs_client->cl_hostname,
182 (long long)NFS_FILEID(inode),
183 (unsigned long long)rdata->args.pgbase,
187 result = NFS_PROTO(inode)->read(rdata);
191 * Even if we had a partial success we can't mark the page
195 if (result == -EISDIR)
200 rdata->args.pgbase += result;
201 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, result);
203 /* Note: result == 0 should only happen if we're caching
204 * a write that extends the file and punches a hole.
206 if (rdata->res.eof != 0 || result == 0)
209 spin_lock(&inode->i_lock);
210 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATIME;
211 spin_unlock(&inode->i_lock);
213 if (rdata->res.eof || rdata->res.count == rdata->args.count) {
214 SetPageUptodate(page);
215 if (rdata->res.eof && count != 0)
216 memclear_highpage_flush(page, rdata->args.pgbase, count);
221 nfs_readdata_free(rdata);
227 static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
230 LIST_HEAD(one_request);
231 struct nfs_page *new;
234 len = nfs_page_length(inode, page);
236 return nfs_return_empty_page(page);
237 new = nfs_create_request(ctx, inode, page, 0, len);
242 if (len < PAGE_CACHE_SIZE)
243 memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
245 nfs_list_add_request(new, &one_request);
246 nfs_pagein_one(&one_request, inode);
250 static void nfs_readpage_release(struct nfs_page *req)
252 unlock_page(req->wb_page);
254 dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",
255 req->wb_context->dentry->d_inode->i_sb->s_id,
256 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
258 (long long)req_offset(req));
259 nfs_clear_request(req);
260 nfs_release_request(req);
264 * Set up the NFS read request struct
266 static void nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
267 const struct rpc_call_ops *call_ops,
268 unsigned int count, unsigned int offset)
274 data->inode = inode = req->wb_context->dentry->d_inode;
275 data->cred = req->wb_context->cred;
277 data->args.fh = NFS_FH(inode);
278 data->args.offset = req_offset(req) + offset;
279 data->args.pgbase = req->wb_pgbase + offset;
280 data->args.pages = data->pagevec;
281 data->args.count = count;
282 data->args.context = req->wb_context;
284 data->res.fattr = &data->fattr;
285 data->res.count = count;
287 nfs_fattr_init(&data->fattr);
289 /* Set up the initial task struct. */
290 flags = RPC_TASK_ASYNC | (IS_SWAPFILE(inode)? NFS_RPC_SWAPFLAGS : 0);
291 rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
292 NFS_PROTO(inode)->read_setup(data);
294 data->task.tk_cookie = (unsigned long)inode;
296 dprintk("NFS: %4d initiated read call (req %s/%Ld, %u bytes @ offset %Lu)\n",
299 (long long)NFS_FILEID(inode),
301 (unsigned long long)data->args.offset);
305 nfs_async_read_error(struct list_head *head)
307 struct nfs_page *req;
309 while (!list_empty(head)) {
310 req = nfs_list_entry(head->next);
311 nfs_list_remove_request(req);
312 SetPageError(req->wb_page);
313 nfs_readpage_release(req);
318 * Start an async read operation
320 static void nfs_execute_read(struct nfs_read_data *data)
322 struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
325 rpc_clnt_sigmask(clnt, &oldset);
327 rpc_execute(&data->task);
329 rpc_clnt_sigunmask(clnt, &oldset);
333 * Generate multiple requests to fill a single page.
335 * We optimize to reduce the number of read operations on the wire. If we
336 * detect that we're reading a page, or an area of a page, that is past the
337 * end of file, we do not generate NFS read operations but just clear the
338 * parts of the page that would have come back zero from the server anyway.
340 * We rely on the cached value of i_size to make this determination; another
341 * client can fill pages on the server past our cached end-of-file, but we
342 * won't see the new data until our attribute cache is updated. This is more
343 * or less conventional NFS client behavior.
345 static int nfs_pagein_multi(struct list_head *head, struct inode *inode)
347 struct nfs_page *req = nfs_list_entry(head->next);
348 struct page *page = req->wb_page;
349 struct nfs_read_data *data;
350 size_t rsize = NFS_SERVER(inode)->rsize, nbytes;
355 nfs_list_remove_request(req);
357 nbytes = req->wb_bytes;
359 size_t len = min(nbytes,rsize);
361 data = nfs_readdata_alloc(len);
364 INIT_LIST_HEAD(&data->pages);
365 list_add(&data->pages, &list);
368 } while(nbytes != 0);
369 atomic_set(&req->wb_complete, requests);
371 ClearPageError(page);
373 nbytes = req->wb_bytes;
375 data = list_entry(list.next, struct nfs_read_data, pages);
376 list_del_init(&data->pages);
378 data->pagevec[0] = page;
380 if (nbytes > rsize) {
381 nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
386 nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
390 nfs_execute_read(data);
391 } while (nbytes != 0);
396 while (!list_empty(&list)) {
397 data = list_entry(list.next, struct nfs_read_data, pages);
398 list_del(&data->pages);
399 nfs_readdata_free(data);
402 nfs_readpage_release(req);
406 static int nfs_pagein_one(struct list_head *head, struct inode *inode)
408 struct nfs_page *req;
410 struct nfs_read_data *data;
413 if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE)
414 return nfs_pagein_multi(head, inode);
416 data = nfs_readdata_alloc(NFS_SERVER(inode)->rsize);
420 INIT_LIST_HEAD(&data->pages);
421 pages = data->pagevec;
423 while (!list_empty(head)) {
424 req = nfs_list_entry(head->next);
425 nfs_list_remove_request(req);
426 nfs_list_add_request(req, &data->pages);
427 ClearPageError(req->wb_page);
428 *pages++ = req->wb_page;
429 count += req->wb_bytes;
431 req = nfs_list_entry(data->pages.next);
433 nfs_read_rpcsetup(req, data, &nfs_read_full_ops, count, 0);
435 nfs_execute_read(data);
438 nfs_async_read_error(head);
443 nfs_pagein_list(struct list_head *head, int rpages)
445 LIST_HEAD(one_request);
446 struct nfs_page *req;
448 unsigned int pages = 0;
450 while (!list_empty(head)) {
451 pages += nfs_coalesce_requests(head, &one_request, rpages);
452 req = nfs_list_entry(one_request.next);
453 error = nfs_pagein_one(&one_request, req->wb_context->dentry->d_inode);
460 nfs_async_read_error(head);
465 * This is the callback from RPC telling us whether a reply was
466 * received or some error occurred (timeout or socket shutdown).
468 int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
472 dprintk("%s: %4d, (status %d)\n", __FUNCTION__, task->tk_pid,
475 status = NFS_PROTO(data->inode)->read_done(task, data);
479 nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, data->res.count);
481 if (task->tk_status == -ESTALE) {
482 set_bit(NFS_INO_STALE, &NFS_FLAGS(data->inode));
483 nfs_mark_for_revalidate(data->inode);
485 spin_lock(&data->inode->i_lock);
486 NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
487 spin_unlock(&data->inode->i_lock);
491 static int nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
493 struct nfs_readargs *argp = &data->args;
494 struct nfs_readres *resp = &data->res;
496 if (resp->eof || resp->count == argp->count)
499 /* This is a short read! */
500 nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
501 /* Has the server at least made some progress? */
502 if (resp->count == 0)
505 /* Yes, so retry the read at the end of the data */
506 argp->offset += resp->count;
507 argp->pgbase += resp->count;
508 argp->count -= resp->count;
509 rpc_restart_call(task);
514 * Handle a read reply that fills part of a page.
516 static void nfs_readpage_result_partial(struct rpc_task *task, void *calldata)
518 struct nfs_read_data *data = calldata;
519 struct nfs_page *req = data->req;
520 struct page *page = req->wb_page;
522 if (nfs_readpage_result(task, data) != 0)
525 if (likely(task->tk_status >= 0)) {
526 nfs_readpage_truncate_uninitialised_page(data);
527 if (nfs_readpage_retry(task, data) != 0)
530 if (unlikely(task->tk_status < 0))
532 if (atomic_dec_and_test(&req->wb_complete)) {
533 if (!PageError(page))
534 SetPageUptodate(page);
535 nfs_readpage_release(req);
539 static const struct rpc_call_ops nfs_read_partial_ops = {
540 .rpc_call_done = nfs_readpage_result_partial,
541 .rpc_release = nfs_readdata_release,
544 static void nfs_readpage_set_pages_uptodate(struct nfs_read_data *data)
546 unsigned int count = data->res.count;
547 unsigned int base = data->args.pgbase;
551 count = data->args.count;
552 if (unlikely(count == 0))
554 pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
555 base &= ~PAGE_CACHE_MASK;
557 for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
558 SetPageUptodate(*pages);
561 /* Was this a short read? */
562 if (data->res.eof || data->res.count == data->args.count)
563 SetPageUptodate(*pages);
567 * This is the callback from RPC telling us whether a reply was
568 * received or some error occurred (timeout or socket shutdown).
570 static void nfs_readpage_result_full(struct rpc_task *task, void *calldata)
572 struct nfs_read_data *data = calldata;
574 if (nfs_readpage_result(task, data) != 0)
577 * Note: nfs_readpage_retry may change the values of
578 * data->args. In the multi-page case, we therefore need
579 * to ensure that we call nfs_readpage_set_pages_uptodate()
582 if (likely(task->tk_status >= 0)) {
583 nfs_readpage_truncate_uninitialised_page(data);
584 nfs_readpage_set_pages_uptodate(data);
585 if (nfs_readpage_retry(task, data) != 0)
588 while (!list_empty(&data->pages)) {
589 struct nfs_page *req = nfs_list_entry(data->pages.next);
591 nfs_list_remove_request(req);
592 nfs_readpage_release(req);
596 static const struct rpc_call_ops nfs_read_full_ops = {
597 .rpc_call_done = nfs_readpage_result_full,
598 .rpc_release = nfs_readdata_release,
602 * Read a page over NFS.
603 * We read the page synchronously in the following case:
604 * - The error flag is set for this page. This happens only when a
605 * previous async read operation failed.
607 int nfs_readpage(struct file *file, struct page *page)
609 struct nfs_open_context *ctx;
610 struct inode *inode = page->mapping->host;
613 dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
614 page, PAGE_CACHE_SIZE, page->index);
615 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
616 nfs_add_stats(inode, NFSIOS_READPAGES, 1);
619 * Try to flush any pending writes to the file..
621 * NOTE! Because we own the page lock, there cannot
622 * be any new pending writes generated at this point
623 * for this page (other pages can be written to).
625 error = nfs_wb_page(inode, page);
630 if (NFS_STALE(inode))
635 ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
639 ctx = get_nfs_open_context((struct nfs_open_context *)
641 if (!IS_SYNC(inode)) {
642 error = nfs_readpage_async(ctx, inode, page);
646 error = nfs_readpage_sync(ctx, inode, page);
647 if (error < 0 && IS_SWAPFILE(inode))
648 printk("Aiee.. nfs swap-in of page failed!\n");
650 put_nfs_open_context(ctx);
658 struct nfs_readdesc {
659 struct list_head *head;
660 struct nfs_open_context *ctx;
664 readpage_async_filler(void *data, struct page *page)
666 struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
667 struct inode *inode = page->mapping->host;
668 struct nfs_page *new;
671 nfs_wb_page(inode, page);
672 len = nfs_page_length(inode, page);
674 return nfs_return_empty_page(page);
675 new = nfs_create_request(desc->ctx, inode, page, 0, len);
681 if (len < PAGE_CACHE_SIZE)
682 memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
683 nfs_list_add_request(new, desc->head);
687 int nfs_readpages(struct file *filp, struct address_space *mapping,
688 struct list_head *pages, unsigned nr_pages)
691 struct nfs_readdesc desc = {
694 struct inode *inode = mapping->host;
695 struct nfs_server *server = NFS_SERVER(inode);
698 dprintk("NFS: nfs_readpages (%s/%Ld %d)\n",
700 (long long)NFS_FILEID(inode),
702 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
704 if (NFS_STALE(inode))
708 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
709 if (desc.ctx == NULL)
712 desc.ctx = get_nfs_open_context((struct nfs_open_context *)
714 ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
715 if (!list_empty(&head)) {
716 int err = nfs_pagein_list(&head, server->rpages);
718 nfs_add_stats(inode, NFSIOS_READPAGES, err);
721 put_nfs_open_context(desc.ctx);
726 int __init nfs_init_readpagecache(void)
728 nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
729 sizeof(struct nfs_read_data),
730 0, SLAB_HWCACHE_ALIGN,
732 if (nfs_rdata_cachep == NULL)
735 nfs_rdata_mempool = mempool_create_slab_pool(MIN_POOL_READ,
737 if (nfs_rdata_mempool == NULL)
743 void nfs_destroy_readpagecache(void)
745 mempool_destroy(nfs_rdata_mempool);
746 kmem_cache_destroy(nfs_rdata_cachep);