blob: 5f20eafba8ecb077e40c593c841a24401f39682a [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/nfs/read.c
3 *
4 * Block I/O for NFS
5 *
6 * Partial copy of Linus' read cache modifications to fs/nfs/file.c
7 * modified for async RPC by okir@monad.swb.de
8 *
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.
16 */
17
18#include <linux/config.h>
19#include <linux/time.h>
20#include <linux/kernel.h>
21#include <linux/errno.h>
22#include <linux/fcntl.h>
23#include <linux/stat.h>
24#include <linux/mm.h>
25#include <linux/slab.h>
26#include <linux/pagemap.h>
27#include <linux/sunrpc/clnt.h>
28#include <linux/nfs_fs.h>
29#include <linux/nfs_page.h>
30#include <linux/smp_lock.h>
31
32#include <asm/system.h>
33
34#define NFSDBG_FACILITY NFSDBG_PAGECACHE
35
36static int nfs_pagein_one(struct list_head *, struct inode *);
37static void nfs_readpage_result_partial(struct nfs_read_data *, int);
38static void nfs_readpage_result_full(struct nfs_read_data *, int);
39
40static kmem_cache_t *nfs_rdata_cachep;
41mempool_t *nfs_rdata_mempool;
42
43#define MIN_POOL_READ (32)
44
45void nfs_readdata_release(struct rpc_task *task)
46{
47 struct nfs_read_data *data = (struct nfs_read_data *)task->tk_calldata;
48 nfs_readdata_free(data);
49}
50
51static
52unsigned int nfs_page_length(struct inode *inode, struct page *page)
53{
54 loff_t i_size = i_size_read(inode);
55 unsigned long idx;
56
57 if (i_size <= 0)
58 return 0;
59 idx = (i_size - 1) >> PAGE_CACHE_SHIFT;
60 if (page->index > idx)
61 return 0;
62 if (page->index != idx)
63 return PAGE_CACHE_SIZE;
64 return 1 + ((i_size - 1) & (PAGE_CACHE_SIZE - 1));
65}
66
67static
68int nfs_return_empty_page(struct page *page)
69{
70 memclear_highpage_flush(page, 0, PAGE_CACHE_SIZE);
71 SetPageUptodate(page);
72 unlock_page(page);
73 return 0;
74}
75
76/*
77 * Read a page synchronously.
78 */
79static int nfs_readpage_sync(struct nfs_open_context *ctx, struct inode *inode,
80 struct page *page)
81{
82 unsigned int rsize = NFS_SERVER(inode)->rsize;
83 unsigned int count = PAGE_CACHE_SIZE;
84 int result;
85 struct nfs_read_data *rdata;
86
87 rdata = nfs_readdata_alloc();
88 if (!rdata)
89 return -ENOMEM;
90
91 memset(rdata, 0, sizeof(*rdata));
92 rdata->flags = (IS_SWAPFILE(inode)? NFS_RPC_SWAPFLAGS : 0);
93 rdata->cred = ctx->cred;
94 rdata->inode = inode;
95 INIT_LIST_HEAD(&rdata->pages);
96 rdata->args.fh = NFS_FH(inode);
97 rdata->args.context = ctx;
98 rdata->args.pages = &page;
99 rdata->args.pgbase = 0UL;
100 rdata->args.count = rsize;
101 rdata->res.fattr = &rdata->fattr;
102
103 dprintk("NFS: nfs_readpage_sync(%p)\n", page);
104
105 /*
106 * This works now because the socket layer never tries to DMA
107 * into this buffer directly.
108 */
109 do {
110 if (count < rsize)
111 rdata->args.count = count;
112 rdata->res.count = rdata->args.count;
113 rdata->args.offset = page_offset(page) + rdata->args.pgbase;
114
115 dprintk("NFS: nfs_proc_read(%s, (%s/%Ld), %Lu, %u)\n",
116 NFS_SERVER(inode)->hostname,
117 inode->i_sb->s_id,
118 (long long)NFS_FILEID(inode),
119 (unsigned long long)rdata->args.pgbase,
120 rdata->args.count);
121
122 lock_kernel();
123 result = NFS_PROTO(inode)->read(rdata);
124 unlock_kernel();
125
126 /*
127 * Even if we had a partial success we can't mark the page
128 * cache valid.
129 */
130 if (result < 0) {
131 if (result == -EISDIR)
132 result = -EINVAL;
133 goto io_error;
134 }
135 count -= result;
136 rdata->args.pgbase += result;
137 /* Note: result == 0 should only happen if we're caching
138 * a write that extends the file and punches a hole.
139 */
140 if (rdata->res.eof != 0 || result == 0)
141 break;
142 } while (count);
Chuck Leverdc592502005-08-18 11:24:12 -0700143 spin_lock(&inode->i_lock);
Chuck Lever55296802005-08-18 11:24:09 -0700144 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATIME;
Chuck Leverdc592502005-08-18 11:24:12 -0700145 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
147 if (count)
148 memclear_highpage_flush(page, rdata->args.pgbase, count);
149 SetPageUptodate(page);
150 if (PageError(page))
151 ClearPageError(page);
152 result = 0;
153
154io_error:
155 unlock_page(page);
156 nfs_readdata_free(rdata);
157 return result;
158}
159
160static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
161 struct page *page)
162{
163 LIST_HEAD(one_request);
164 struct nfs_page *new;
165 unsigned int len;
166
167 len = nfs_page_length(inode, page);
168 if (len == 0)
169 return nfs_return_empty_page(page);
170 new = nfs_create_request(ctx, inode, page, 0, len);
171 if (IS_ERR(new)) {
172 unlock_page(page);
173 return PTR_ERR(new);
174 }
175 if (len < PAGE_CACHE_SIZE)
176 memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
177
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 nfs_list_add_request(new, &one_request);
179 nfs_pagein_one(&one_request, inode);
180 return 0;
181}
182
183static void nfs_readpage_release(struct nfs_page *req)
184{
185 unlock_page(req->wb_page);
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",
188 req->wb_context->dentry->d_inode->i_sb->s_id,
189 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
190 req->wb_bytes,
191 (long long)req_offset(req));
Nick Wilson10d2c462005-09-22 21:44:28 -0700192 nfs_clear_request(req);
193 nfs_release_request(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194}
195
196/*
197 * Set up the NFS read request struct
198 */
199static void nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
200 unsigned int count, unsigned int offset)
201{
202 struct inode *inode;
203
204 data->req = req;
205 data->inode = inode = req->wb_context->dentry->d_inode;
206 data->cred = req->wb_context->cred;
207
208 data->args.fh = NFS_FH(inode);
209 data->args.offset = req_offset(req) + offset;
210 data->args.pgbase = req->wb_pgbase + offset;
211 data->args.pages = data->pagevec;
212 data->args.count = count;
213 data->args.context = req->wb_context;
214
215 data->res.fattr = &data->fattr;
216 data->res.count = count;
217 data->res.eof = 0;
Trond Myklebust0e574af2005-10-27 22:12:38 -0400218 nfs_fattr_init(&data->fattr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219
220 NFS_PROTO(inode)->read_setup(data);
221
222 data->task.tk_cookie = (unsigned long)inode;
223 data->task.tk_calldata = data;
224 /* Release requests */
225 data->task.tk_release = nfs_readdata_release;
226
227 dprintk("NFS: %4d initiated read call (req %s/%Ld, %u bytes @ offset %Lu)\n",
228 data->task.tk_pid,
229 inode->i_sb->s_id,
230 (long long)NFS_FILEID(inode),
231 count,
232 (unsigned long long)data->args.offset);
233}
234
235static void
236nfs_async_read_error(struct list_head *head)
237{
238 struct nfs_page *req;
239
240 while (!list_empty(head)) {
241 req = nfs_list_entry(head->next);
242 nfs_list_remove_request(req);
243 SetPageError(req->wb_page);
244 nfs_readpage_release(req);
245 }
246}
247
248/*
249 * Start an async read operation
250 */
251static void nfs_execute_read(struct nfs_read_data *data)
252{
253 struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
254 sigset_t oldset;
255
256 rpc_clnt_sigmask(clnt, &oldset);
257 lock_kernel();
258 rpc_execute(&data->task);
259 unlock_kernel();
260 rpc_clnt_sigunmask(clnt, &oldset);
261}
262
263/*
264 * Generate multiple requests to fill a single page.
265 *
266 * We optimize to reduce the number of read operations on the wire. If we
267 * detect that we're reading a page, or an area of a page, that is past the
268 * end of file, we do not generate NFS read operations but just clear the
269 * parts of the page that would have come back zero from the server anyway.
270 *
271 * We rely on the cached value of i_size to make this determination; another
272 * client can fill pages on the server past our cached end-of-file, but we
273 * won't see the new data until our attribute cache is updated. This is more
274 * or less conventional NFS client behavior.
275 */
276static int nfs_pagein_multi(struct list_head *head, struct inode *inode)
277{
278 struct nfs_page *req = nfs_list_entry(head->next);
279 struct page *page = req->wb_page;
280 struct nfs_read_data *data;
281 unsigned int rsize = NFS_SERVER(inode)->rsize;
282 unsigned int nbytes, offset;
283 int requests = 0;
284 LIST_HEAD(list);
285
286 nfs_list_remove_request(req);
287
288 nbytes = req->wb_bytes;
289 for(;;) {
290 data = nfs_readdata_alloc();
291 if (!data)
292 goto out_bad;
293 INIT_LIST_HEAD(&data->pages);
294 list_add(&data->pages, &list);
295 requests++;
296 if (nbytes <= rsize)
297 break;
298 nbytes -= rsize;
299 }
300 atomic_set(&req->wb_complete, requests);
301
302 ClearPageError(page);
303 offset = 0;
304 nbytes = req->wb_bytes;
305 do {
306 data = list_entry(list.next, struct nfs_read_data, pages);
307 list_del_init(&data->pages);
308
309 data->pagevec[0] = page;
310 data->complete = nfs_readpage_result_partial;
311
312 if (nbytes > rsize) {
313 nfs_read_rpcsetup(req, data, rsize, offset);
314 offset += rsize;
315 nbytes -= rsize;
316 } else {
317 nfs_read_rpcsetup(req, data, nbytes, offset);
318 nbytes = 0;
319 }
320 nfs_execute_read(data);
321 } while (nbytes != 0);
322
323 return 0;
324
325out_bad:
326 while (!list_empty(&list)) {
327 data = list_entry(list.next, struct nfs_read_data, pages);
328 list_del(&data->pages);
329 nfs_readdata_free(data);
330 }
331 SetPageError(page);
332 nfs_readpage_release(req);
333 return -ENOMEM;
334}
335
336static int nfs_pagein_one(struct list_head *head, struct inode *inode)
337{
338 struct nfs_page *req;
339 struct page **pages;
340 struct nfs_read_data *data;
341 unsigned int count;
342
343 if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE)
344 return nfs_pagein_multi(head, inode);
345
346 data = nfs_readdata_alloc();
347 if (!data)
348 goto out_bad;
349
350 INIT_LIST_HEAD(&data->pages);
351 pages = data->pagevec;
352 count = 0;
353 while (!list_empty(head)) {
354 req = nfs_list_entry(head->next);
355 nfs_list_remove_request(req);
356 nfs_list_add_request(req, &data->pages);
357 ClearPageError(req->wb_page);
358 *pages++ = req->wb_page;
359 count += req->wb_bytes;
360 }
361 req = nfs_list_entry(data->pages.next);
362
363 data->complete = nfs_readpage_result_full;
364 nfs_read_rpcsetup(req, data, count, 0);
365
366 nfs_execute_read(data);
367 return 0;
368out_bad:
369 nfs_async_read_error(head);
370 return -ENOMEM;
371}
372
373static int
374nfs_pagein_list(struct list_head *head, int rpages)
375{
376 LIST_HEAD(one_request);
377 struct nfs_page *req;
378 int error = 0;
379 unsigned int pages = 0;
380
381 while (!list_empty(head)) {
382 pages += nfs_coalesce_requests(head, &one_request, rpages);
383 req = nfs_list_entry(one_request.next);
384 error = nfs_pagein_one(&one_request, req->wb_context->dentry->d_inode);
385 if (error < 0)
386 break;
387 }
388 if (error >= 0)
389 return pages;
390
391 nfs_async_read_error(head);
392 return error;
393}
394
395/*
396 * Handle a read reply that fills part of a page.
397 */
398static void nfs_readpage_result_partial(struct nfs_read_data *data, int status)
399{
400 struct nfs_page *req = data->req;
401 struct page *page = req->wb_page;
402
403 if (status >= 0) {
404 unsigned int request = data->args.count;
405 unsigned int result = data->res.count;
406
407 if (result < request) {
408 memclear_highpage_flush(page,
409 data->args.pgbase + result,
410 request - result);
411 }
412 } else
413 SetPageError(page);
414
415 if (atomic_dec_and_test(&req->wb_complete)) {
416 if (!PageError(page))
417 SetPageUptodate(page);
418 nfs_readpage_release(req);
419 }
420}
421
422/*
423 * This is the callback from RPC telling us whether a reply was
424 * received or some error occurred (timeout or socket shutdown).
425 */
426static void nfs_readpage_result_full(struct nfs_read_data *data, int status)
427{
428 unsigned int count = data->res.count;
429
430 while (!list_empty(&data->pages)) {
431 struct nfs_page *req = nfs_list_entry(data->pages.next);
432 struct page *page = req->wb_page;
433 nfs_list_remove_request(req);
434
435 if (status >= 0) {
436 if (count < PAGE_CACHE_SIZE) {
437 if (count < req->wb_bytes)
438 memclear_highpage_flush(page,
439 req->wb_pgbase + count,
440 req->wb_bytes - count);
441 count = 0;
442 } else
443 count -= PAGE_CACHE_SIZE;
444 SetPageUptodate(page);
445 } else
446 SetPageError(page);
447 nfs_readpage_release(req);
448 }
449}
450
451/*
452 * This is the callback from RPC telling us whether a reply was
453 * received or some error occurred (timeout or socket shutdown).
454 */
455void nfs_readpage_result(struct rpc_task *task)
456{
457 struct nfs_read_data *data = (struct nfs_read_data *)task->tk_calldata;
458 struct nfs_readargs *argp = &data->args;
459 struct nfs_readres *resp = &data->res;
460 int status = task->tk_status;
461
462 dprintk("NFS: %4d nfs_readpage_result, (status %d)\n",
463 task->tk_pid, status);
464
465 /* Is this a short read? */
466 if (task->tk_status >= 0 && resp->count < argp->count && !resp->eof) {
467 /* Has the server at least made some progress? */
468 if (resp->count != 0) {
469 /* Yes, so retry the read at the end of the data */
470 argp->offset += resp->count;
471 argp->pgbase += resp->count;
472 argp->count -= resp->count;
473 rpc_restart_call(task);
474 return;
475 }
476 task->tk_status = -EIO;
477 }
Chuck Leverdc592502005-08-18 11:24:12 -0700478 spin_lock(&data->inode->i_lock);
Chuck Lever55296802005-08-18 11:24:09 -0700479 NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
Chuck Leverdc592502005-08-18 11:24:12 -0700480 spin_unlock(&data->inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 data->complete(data, status);
482}
483
484/*
485 * Read a page over NFS.
486 * We read the page synchronously in the following case:
487 * - The error flag is set for this page. This happens only when a
488 * previous async read operation failed.
489 */
490int nfs_readpage(struct file *file, struct page *page)
491{
492 struct nfs_open_context *ctx;
493 struct inode *inode = page->mapping->host;
494 int error;
495
496 dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
497 page, PAGE_CACHE_SIZE, page->index);
498 /*
499 * Try to flush any pending writes to the file..
500 *
501 * NOTE! Because we own the page lock, there cannot
502 * be any new pending writes generated at this point
503 * for this page (other pages can be written to).
504 */
505 error = nfs_wb_page(inode, page);
506 if (error)
507 goto out_error;
508
509 if (file == NULL) {
Trond Myklebustd5308382005-11-04 15:33:38 -0500510 ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 if (ctx == NULL)
512 return -EBADF;
513 } else
514 ctx = get_nfs_open_context((struct nfs_open_context *)
515 file->private_data);
516 if (!IS_SYNC(inode)) {
517 error = nfs_readpage_async(ctx, inode, page);
518 goto out;
519 }
520
521 error = nfs_readpage_sync(ctx, inode, page);
522 if (error < 0 && IS_SWAPFILE(inode))
523 printk("Aiee.. nfs swap-in of page failed!\n");
524out:
525 put_nfs_open_context(ctx);
526 return error;
527
528out_error:
529 unlock_page(page);
530 return error;
531}
532
533struct nfs_readdesc {
534 struct list_head *head;
535 struct nfs_open_context *ctx;
536};
537
538static int
539readpage_async_filler(void *data, struct page *page)
540{
541 struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
542 struct inode *inode = page->mapping->host;
543 struct nfs_page *new;
544 unsigned int len;
545
546 nfs_wb_page(inode, page);
547 len = nfs_page_length(inode, page);
548 if (len == 0)
549 return nfs_return_empty_page(page);
550 new = nfs_create_request(desc->ctx, inode, page, 0, len);
551 if (IS_ERR(new)) {
552 SetPageError(page);
553 unlock_page(page);
554 return PTR_ERR(new);
555 }
556 if (len < PAGE_CACHE_SIZE)
557 memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 nfs_list_add_request(new, desc->head);
559 return 0;
560}
561
562int nfs_readpages(struct file *filp, struct address_space *mapping,
563 struct list_head *pages, unsigned nr_pages)
564{
565 LIST_HEAD(head);
566 struct nfs_readdesc desc = {
567 .head = &head,
568 };
569 struct inode *inode = mapping->host;
570 struct nfs_server *server = NFS_SERVER(inode);
571 int ret;
572
573 dprintk("NFS: nfs_readpages (%s/%Ld %d)\n",
574 inode->i_sb->s_id,
575 (long long)NFS_FILEID(inode),
576 nr_pages);
577
578 if (filp == NULL) {
Trond Myklebustd5308382005-11-04 15:33:38 -0500579 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 if (desc.ctx == NULL)
581 return -EBADF;
582 } else
583 desc.ctx = get_nfs_open_context((struct nfs_open_context *)
584 filp->private_data);
585 ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
586 if (!list_empty(&head)) {
587 int err = nfs_pagein_list(&head, server->rpages);
588 if (!ret)
589 ret = err;
590 }
591 put_nfs_open_context(desc.ctx);
592 return ret;
593}
594
595int nfs_init_readpagecache(void)
596{
597 nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
598 sizeof(struct nfs_read_data),
599 0, SLAB_HWCACHE_ALIGN,
600 NULL, NULL);
601 if (nfs_rdata_cachep == NULL)
602 return -ENOMEM;
603
604 nfs_rdata_mempool = mempool_create(MIN_POOL_READ,
605 mempool_alloc_slab,
606 mempool_free_slab,
607 nfs_rdata_cachep);
608 if (nfs_rdata_mempool == NULL)
609 return -ENOMEM;
610
611 return 0;
612}
613
614void nfs_destroy_readpagecache(void)
615{
616 mempool_destroy(nfs_rdata_mempool);
617 if (kmem_cache_destroy(nfs_rdata_cachep))
618 printk(KERN_INFO "nfs_read_data: not all structures were freed\n");
619}