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1/*
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
10#include <linux/time.h>
11#include <linux/kernel.h>
12#include <linux/errno.h>
13#include <linux/fcntl.h>
14#include <linux/stat.h>
15#include <linux/mm.h>
16#include <linux/slab.h>
17#include <linux/pagemap.h>
18#include <linux/sunrpc/clnt.h>
19#include <linux/nfs_fs.h>
20#include <linux/nfs_page.h>
21#include <linux/module.h>
22
23#include "nfs4_fs.h"
24#include "internal.h"
25#include "iostat.h"
26#include "fscache.h"
27#include "pnfs.h"
28
29#define NFSDBG_FACILITY NFSDBG_PAGECACHE
30
31static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
32static const struct nfs_rw_ops nfs_rw_read_ops;
33
34static struct kmem_cache *nfs_rdata_cachep;
35
36static struct nfs_pgio_header *nfs_readhdr_alloc(void)
37{
38 return kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
39}
40
41static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
42{
43 kmem_cache_free(nfs_rdata_cachep, rhdr);
44}
45
46static
47int nfs_return_empty_page(struct page *page)
48{
49 zero_user(page, 0, PAGE_SIZE);
50 SetPageUptodate(page);
51 unlock_page(page);
52 return 0;
53}
54
55void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
56 struct inode *inode, bool force_mds,
57 const struct nfs_pgio_completion_ops *compl_ops)
58{
59 struct nfs_server *server = NFS_SERVER(inode);
60 const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
61
62#ifdef CONFIG_NFS_V4_1
63 if (server->pnfs_curr_ld && !force_mds)
64 pg_ops = server->pnfs_curr_ld->pg_read_ops;
65#endif
66 nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
67 server->rsize, 0);
68}
69EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
70
71void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
72{
73 struct nfs_pgio_mirror *mirror;
74
75 if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
76 pgio->pg_ops->pg_cleanup(pgio);
77
78 pgio->pg_ops = &nfs_pgio_rw_ops;
79
80 /* read path should never have more than one mirror */
81 WARN_ON_ONCE(pgio->pg_mirror_count != 1);
82
83 mirror = &pgio->pg_mirrors[0];
84 mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
85}
86EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
87
88static void nfs_readpage_release(struct nfs_page *req)
89{
90 struct inode *inode = d_inode(req->wb_context->dentry);
91
92 dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
93 (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
94 (long long)req_offset(req));
95
96 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
97 if (PageUptodate(req->wb_page))
98 nfs_readpage_to_fscache(inode, req->wb_page, 0);
99
100 unlock_page(req->wb_page);
101 }
102 nfs_release_request(req);
103}
104
105int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
106 struct page *page)
107{
108 struct nfs_page *new;
109 unsigned int len;
110 struct nfs_pageio_descriptor pgio;
111 struct nfs_pgio_mirror *pgm;
112
113 len = nfs_page_length(page);
114 if (len == 0)
115 return nfs_return_empty_page(page);
116 new = nfs_create_request(ctx, page, NULL, 0, len);
117 if (IS_ERR(new)) {
118 unlock_page(page);
119 return PTR_ERR(new);
120 }
121 if (len < PAGE_SIZE)
122 zero_user_segment(page, len, PAGE_SIZE);
123
124 nfs_pageio_init_read(&pgio, inode, false,
125 &nfs_async_read_completion_ops);
126 if (!nfs_pageio_add_request(&pgio, new)) {
127 nfs_list_remove_request(new);
128 nfs_readpage_release(new);
129 }
130 nfs_pageio_complete(&pgio);
131
132 /* It doesn't make sense to do mirrored reads! */
133 WARN_ON_ONCE(pgio.pg_mirror_count != 1);
134
135 pgm = &pgio.pg_mirrors[0];
136 NFS_I(inode)->read_io += pgm->pg_bytes_written;
137
138 return pgio.pg_error < 0 ? pgio.pg_error : 0;
139}
140
141static void nfs_page_group_set_uptodate(struct nfs_page *req)
142{
143 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
144 SetPageUptodate(req->wb_page);
145}
146
147static void nfs_read_completion(struct nfs_pgio_header *hdr)
148{
149 unsigned long bytes = 0;
150
151 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
152 goto out;
153 while (!list_empty(&hdr->pages)) {
154 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
155 struct page *page = req->wb_page;
156 unsigned long start = req->wb_pgbase;
157 unsigned long end = req->wb_pgbase + req->wb_bytes;
158
159 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
160 /* note: regions of the page not covered by a
161 * request are zeroed in nfs_readpage_async /
162 * readpage_async_filler */
163 if (bytes > hdr->good_bytes) {
164 /* nothing in this request was good, so zero
165 * the full extent of the request */
166 zero_user_segment(page, start, end);
167
168 } else if (hdr->good_bytes - bytes < req->wb_bytes) {
169 /* part of this request has good bytes, but
170 * not all. zero the bad bytes */
171 start += hdr->good_bytes - bytes;
172 WARN_ON(start < req->wb_pgbase);
173 zero_user_segment(page, start, end);
174 }
175 }
176 bytes += req->wb_bytes;
177 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
178 if (bytes <= hdr->good_bytes)
179 nfs_page_group_set_uptodate(req);
180 } else
181 nfs_page_group_set_uptodate(req);
182 nfs_list_remove_request(req);
183 nfs_readpage_release(req);
184 }
185out:
186 hdr->release(hdr);
187}
188
189static void nfs_initiate_read(struct nfs_pgio_header *hdr,
190 struct rpc_message *msg,
191 const struct nfs_rpc_ops *rpc_ops,
192 struct rpc_task_setup *task_setup_data, int how)
193{
194 struct inode *inode = hdr->inode;
195 int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
196
197 task_setup_data->flags |= swap_flags;
198 rpc_ops->read_setup(hdr, msg);
199}
200
201static void
202nfs_async_read_error(struct list_head *head)
203{
204 struct nfs_page *req;
205
206 while (!list_empty(head)) {
207 req = nfs_list_entry(head->next);
208 nfs_list_remove_request(req);
209 nfs_readpage_release(req);
210 }
211}
212
213static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
214 .error_cleanup = nfs_async_read_error,
215 .completion = nfs_read_completion,
216};
217
218/*
219 * This is the callback from RPC telling us whether a reply was
220 * received or some error occurred (timeout or socket shutdown).
221 */
222static int nfs_readpage_done(struct rpc_task *task,
223 struct nfs_pgio_header *hdr,
224 struct inode *inode)
225{
226 int status = NFS_PROTO(inode)->read_done(task, hdr);
227 if (status != 0)
228 return status;
229
230 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
231
232 if (task->tk_status == -ESTALE) {
233 set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
234 nfs_mark_for_revalidate(inode);
235 }
236 return 0;
237}
238
239static void nfs_readpage_retry(struct rpc_task *task,
240 struct nfs_pgio_header *hdr)
241{
242 struct nfs_pgio_args *argp = &hdr->args;
243 struct nfs_pgio_res *resp = &hdr->res;
244
245 /* This is a short read! */
246 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
247 /* Has the server at least made some progress? */
248 if (resp->count == 0) {
249 nfs_set_pgio_error(hdr, -EIO, argp->offset);
250 return;
251 }
252
253 /* For non rpc-based layout drivers, retry-through-MDS */
254 if (!task->tk_ops) {
255 hdr->pnfs_error = -EAGAIN;
256 return;
257 }
258
259 /* Yes, so retry the read at the end of the hdr */
260 hdr->mds_offset += resp->count;
261 argp->offset += resp->count;
262 argp->pgbase += resp->count;
263 argp->count -= resp->count;
264 rpc_restart_call_prepare(task);
265}
266
267static void nfs_readpage_result(struct rpc_task *task,
268 struct nfs_pgio_header *hdr)
269{
270 if (hdr->res.eof) {
271 loff_t bound;
272
273 bound = hdr->args.offset + hdr->res.count;
274 spin_lock(&hdr->lock);
275 if (bound < hdr->io_start + hdr->good_bytes) {
276 set_bit(NFS_IOHDR_EOF, &hdr->flags);
277 clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
278 hdr->good_bytes = bound - hdr->io_start;
279 }
280 spin_unlock(&hdr->lock);
281 } else if (hdr->res.count < hdr->args.count)
282 nfs_readpage_retry(task, hdr);
283}
284
285/*
286 * Read a page over NFS.
287 * We read the page synchronously in the following case:
288 * - The error flag is set for this page. This happens only when a
289 * previous async read operation failed.
290 */
291int nfs_readpage(struct file *file, struct page *page)
292{
293 struct nfs_open_context *ctx;
294 struct inode *inode = page_file_mapping(page)->host;
295 int error;
296
297 dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
298 page, PAGE_SIZE, page_index(page));
299 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
300 nfs_add_stats(inode, NFSIOS_READPAGES, 1);
301
302 /*
303 * Try to flush any pending writes to the file..
304 *
305 * NOTE! Because we own the page lock, there cannot
306 * be any new pending writes generated at this point
307 * for this page (other pages can be written to).
308 */
309 error = nfs_wb_page(inode, page);
310 if (error)
311 goto out_unlock;
312 if (PageUptodate(page))
313 goto out_unlock;
314
315 error = -ESTALE;
316 if (NFS_STALE(inode))
317 goto out_unlock;
318
319 if (file == NULL) {
320 error = -EBADF;
321 ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
322 if (ctx == NULL)
323 goto out_unlock;
324 } else
325 ctx = get_nfs_open_context(nfs_file_open_context(file));
326
327 if (!IS_SYNC(inode)) {
328 error = nfs_readpage_from_fscache(ctx, inode, page);
329 if (error == 0)
330 goto out;
331 }
332
333 error = nfs_readpage_async(ctx, inode, page);
334
335out:
336 put_nfs_open_context(ctx);
337 return error;
338out_unlock:
339 unlock_page(page);
340 return error;
341}
342
343struct nfs_readdesc {
344 struct nfs_pageio_descriptor *pgio;
345 struct nfs_open_context *ctx;
346};
347
348static int
349readpage_async_filler(void *data, struct page *page)
350{
351 struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
352 struct nfs_page *new;
353 unsigned int len;
354 int error;
355
356 len = nfs_page_length(page);
357 if (len == 0)
358 return nfs_return_empty_page(page);
359
360 new = nfs_create_request(desc->ctx, page, NULL, 0, len);
361 if (IS_ERR(new))
362 goto out_error;
363
364 if (len < PAGE_SIZE)
365 zero_user_segment(page, len, PAGE_SIZE);
366 if (!nfs_pageio_add_request(desc->pgio, new)) {
367 nfs_list_remove_request(new);
368 nfs_readpage_release(new);
369 error = desc->pgio->pg_error;
370 goto out;
371 }
372 return 0;
373out_error:
374 error = PTR_ERR(new);
375 unlock_page(page);
376out:
377 return error;
378}
379
380int nfs_readpages(struct file *filp, struct address_space *mapping,
381 struct list_head *pages, unsigned nr_pages)
382{
383 struct nfs_pageio_descriptor pgio;
384 struct nfs_pgio_mirror *pgm;
385 struct nfs_readdesc desc = {
386 .pgio = &pgio,
387 };
388 struct inode *inode = mapping->host;
389 unsigned long npages;
390 int ret = -ESTALE;
391
392 dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
393 inode->i_sb->s_id,
394 (unsigned long long)NFS_FILEID(inode),
395 nr_pages);
396 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
397
398 if (NFS_STALE(inode))
399 goto out;
400
401 if (filp == NULL) {
402 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
403 if (desc.ctx == NULL)
404 return -EBADF;
405 } else
406 desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
407
408 /* attempt to read as many of the pages as possible from the cache
409 * - this returns -ENOBUFS immediately if the cookie is negative
410 */
411 ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
412 pages, &nr_pages);
413 if (ret == 0)
414 goto read_complete; /* all pages were read */
415
416 nfs_pageio_init_read(&pgio, inode, false,
417 &nfs_async_read_completion_ops);
418
419 ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
420 nfs_pageio_complete(&pgio);
421
422 /* It doesn't make sense to do mirrored reads! */
423 WARN_ON_ONCE(pgio.pg_mirror_count != 1);
424
425 pgm = &pgio.pg_mirrors[0];
426 NFS_I(inode)->read_io += pgm->pg_bytes_written;
427 npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >>
428 PAGE_SHIFT;
429 nfs_add_stats(inode, NFSIOS_READPAGES, npages);
430read_complete:
431 put_nfs_open_context(desc.ctx);
432out:
433 return ret;
434}
435
436int __init nfs_init_readpagecache(void)
437{
438 nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
439 sizeof(struct nfs_pgio_header),
440 0, SLAB_HWCACHE_ALIGN,
441 NULL);
442 if (nfs_rdata_cachep == NULL)
443 return -ENOMEM;
444
445 return 0;
446}
447
448void nfs_destroy_readpagecache(void)
449{
450 kmem_cache_destroy(nfs_rdata_cachep);
451}
452
453static const struct nfs_rw_ops nfs_rw_read_ops = {
454 .rw_mode = FMODE_READ,
455 .rw_alloc_header = nfs_readhdr_alloc,
456 .rw_free_header = nfs_readhdr_free,
457 .rw_done = nfs_readpage_done,
458 .rw_result = nfs_readpage_result,
459 .rw_initiate = nfs_initiate_read,
460};
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/nfs/read.c
4 *
5 * Block I/O for NFS
6 *
7 * Partial copy of Linus' read cache modifications to fs/nfs/file.c
8 * modified for async RPC by okir@monad.swb.de
9 */
10
11#include <linux/time.h>
12#include <linux/kernel.h>
13#include <linux/errno.h>
14#include <linux/fcntl.h>
15#include <linux/stat.h>
16#include <linux/mm.h>
17#include <linux/slab.h>
18#include <linux/pagemap.h>
19#include <linux/sunrpc/clnt.h>
20#include <linux/nfs_fs.h>
21#include <linux/nfs_page.h>
22#include <linux/module.h>
23
24#include "nfs4_fs.h"
25#include "internal.h"
26#include "iostat.h"
27#include "fscache.h"
28#include "pnfs.h"
29#include "nfstrace.h"
30
31#define NFSDBG_FACILITY NFSDBG_PAGECACHE
32
33static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
34static const struct nfs_rw_ops nfs_rw_read_ops;
35
36static struct kmem_cache *nfs_rdata_cachep;
37
38static struct nfs_pgio_header *nfs_readhdr_alloc(void)
39{
40 struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
41
42 if (p)
43 p->rw_mode = FMODE_READ;
44 return p;
45}
46
47static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
48{
49 kmem_cache_free(nfs_rdata_cachep, rhdr);
50}
51
52static
53int nfs_return_empty_page(struct page *page)
54{
55 zero_user(page, 0, PAGE_SIZE);
56 SetPageUptodate(page);
57 unlock_page(page);
58 return 0;
59}
60
61void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
62 struct inode *inode, bool force_mds,
63 const struct nfs_pgio_completion_ops *compl_ops)
64{
65 struct nfs_server *server = NFS_SERVER(inode);
66 const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
67
68#ifdef CONFIG_NFS_V4_1
69 if (server->pnfs_curr_ld && !force_mds)
70 pg_ops = server->pnfs_curr_ld->pg_read_ops;
71#endif
72 nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
73 server->rsize, 0);
74}
75EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
76
77static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
78{
79 struct nfs_pgio_mirror *pgm;
80 unsigned long npages;
81
82 nfs_pageio_complete(pgio);
83
84 /* It doesn't make sense to do mirrored reads! */
85 WARN_ON_ONCE(pgio->pg_mirror_count != 1);
86
87 pgm = &pgio->pg_mirrors[0];
88 NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
89 npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
90 nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
91}
92
93
94void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
95{
96 struct nfs_pgio_mirror *mirror;
97
98 if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
99 pgio->pg_ops->pg_cleanup(pgio);
100
101 pgio->pg_ops = &nfs_pgio_rw_ops;
102
103 /* read path should never have more than one mirror */
104 WARN_ON_ONCE(pgio->pg_mirror_count != 1);
105
106 mirror = &pgio->pg_mirrors[0];
107 mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
108}
109EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
110
111static void nfs_readpage_release(struct nfs_page *req, int error)
112{
113 struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
114 struct page *page = req->wb_page;
115
116 dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
117 (unsigned long long)NFS_FILEID(inode), req->wb_bytes,
118 (long long)req_offset(req));
119
120 if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
121 SetPageError(page);
122 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
123 if (PageUptodate(page))
124 nfs_fscache_write_page(inode, page);
125 unlock_page(page);
126 }
127 nfs_release_request(req);
128}
129
130struct nfs_readdesc {
131 struct nfs_pageio_descriptor pgio;
132 struct nfs_open_context *ctx;
133};
134
135static void nfs_page_group_set_uptodate(struct nfs_page *req)
136{
137 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
138 SetPageUptodate(req->wb_page);
139}
140
141static void nfs_read_completion(struct nfs_pgio_header *hdr)
142{
143 unsigned long bytes = 0;
144 int error;
145
146 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
147 goto out;
148 while (!list_empty(&hdr->pages)) {
149 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
150 struct page *page = req->wb_page;
151 unsigned long start = req->wb_pgbase;
152 unsigned long end = req->wb_pgbase + req->wb_bytes;
153
154 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
155 /* note: regions of the page not covered by a
156 * request are zeroed in readpage_async_filler */
157 if (bytes > hdr->good_bytes) {
158 /* nothing in this request was good, so zero
159 * the full extent of the request */
160 zero_user_segment(page, start, end);
161
162 } else if (hdr->good_bytes - bytes < req->wb_bytes) {
163 /* part of this request has good bytes, but
164 * not all. zero the bad bytes */
165 start += hdr->good_bytes - bytes;
166 WARN_ON(start < req->wb_pgbase);
167 zero_user_segment(page, start, end);
168 }
169 }
170 error = 0;
171 bytes += req->wb_bytes;
172 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
173 if (bytes <= hdr->good_bytes)
174 nfs_page_group_set_uptodate(req);
175 else {
176 error = hdr->error;
177 xchg(&nfs_req_openctx(req)->error, error);
178 }
179 } else
180 nfs_page_group_set_uptodate(req);
181 nfs_list_remove_request(req);
182 nfs_readpage_release(req, error);
183 }
184out:
185 hdr->release(hdr);
186}
187
188static void nfs_initiate_read(struct nfs_pgio_header *hdr,
189 struct rpc_message *msg,
190 const struct nfs_rpc_ops *rpc_ops,
191 struct rpc_task_setup *task_setup_data, int how)
192{
193 rpc_ops->read_setup(hdr, msg);
194 trace_nfs_initiate_read(hdr);
195}
196
197static void
198nfs_async_read_error(struct list_head *head, int error)
199{
200 struct nfs_page *req;
201
202 while (!list_empty(head)) {
203 req = nfs_list_entry(head->next);
204 nfs_list_remove_request(req);
205 nfs_readpage_release(req, error);
206 }
207}
208
209static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
210 .error_cleanup = nfs_async_read_error,
211 .completion = nfs_read_completion,
212};
213
214/*
215 * This is the callback from RPC telling us whether a reply was
216 * received or some error occurred (timeout or socket shutdown).
217 */
218static int nfs_readpage_done(struct rpc_task *task,
219 struct nfs_pgio_header *hdr,
220 struct inode *inode)
221{
222 int status = NFS_PROTO(inode)->read_done(task, hdr);
223 if (status != 0)
224 return status;
225
226 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
227 trace_nfs_readpage_done(task, hdr);
228
229 if (task->tk_status == -ESTALE) {
230 nfs_set_inode_stale(inode);
231 nfs_mark_for_revalidate(inode);
232 }
233 return 0;
234}
235
236static void nfs_readpage_retry(struct rpc_task *task,
237 struct nfs_pgio_header *hdr)
238{
239 struct nfs_pgio_args *argp = &hdr->args;
240 struct nfs_pgio_res *resp = &hdr->res;
241
242 /* This is a short read! */
243 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
244 trace_nfs_readpage_short(task, hdr);
245
246 /* Has the server at least made some progress? */
247 if (resp->count == 0) {
248 nfs_set_pgio_error(hdr, -EIO, argp->offset);
249 return;
250 }
251
252 /* For non rpc-based layout drivers, retry-through-MDS */
253 if (!task->tk_ops) {
254 hdr->pnfs_error = -EAGAIN;
255 return;
256 }
257
258 /* Yes, so retry the read at the end of the hdr */
259 hdr->mds_offset += resp->count;
260 argp->offset += resp->count;
261 argp->pgbase += resp->count;
262 argp->count -= resp->count;
263 resp->count = 0;
264 resp->eof = 0;
265 rpc_restart_call_prepare(task);
266}
267
268static void nfs_readpage_result(struct rpc_task *task,
269 struct nfs_pgio_header *hdr)
270{
271 if (hdr->res.eof) {
272 loff_t pos = hdr->args.offset + hdr->res.count;
273 unsigned int new = pos - hdr->io_start;
274
275 if (hdr->good_bytes > new) {
276 hdr->good_bytes = new;
277 set_bit(NFS_IOHDR_EOF, &hdr->flags);
278 clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
279 }
280 } else if (hdr->res.count < hdr->args.count)
281 nfs_readpage_retry(task, hdr);
282}
283
284static int
285readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
286{
287 struct inode *inode = page_file_mapping(page)->host;
288 unsigned int rsize = NFS_SERVER(inode)->rsize;
289 struct nfs_page *new;
290 unsigned int len, aligned_len;
291 int error;
292
293 len = nfs_page_length(page);
294 if (len == 0)
295 return nfs_return_empty_page(page);
296
297 aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
298
299 if (!IS_SYNC(page->mapping->host)) {
300 error = nfs_fscache_read_page(page->mapping->host, page);
301 if (error == 0)
302 goto out_unlock;
303 }
304
305 new = nfs_create_request(desc->ctx, page, 0, aligned_len);
306 if (IS_ERR(new))
307 goto out_error;
308
309 if (len < PAGE_SIZE)
310 zero_user_segment(page, len, PAGE_SIZE);
311 if (!nfs_pageio_add_request(&desc->pgio, new)) {
312 nfs_list_remove_request(new);
313 error = desc->pgio.pg_error;
314 nfs_readpage_release(new, error);
315 goto out;
316 }
317 return 0;
318out_error:
319 error = PTR_ERR(new);
320out_unlock:
321 unlock_page(page);
322out:
323 return error;
324}
325
326/*
327 * Read a page over NFS.
328 * We read the page synchronously in the following case:
329 * - The error flag is set for this page. This happens only when a
330 * previous async read operation failed.
331 */
332int nfs_read_folio(struct file *file, struct folio *folio)
333{
334 struct page *page = &folio->page;
335 struct nfs_readdesc desc;
336 struct inode *inode = page_file_mapping(page)->host;
337 int ret;
338
339 trace_nfs_aop_readpage(inode, page);
340 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
341
342 /*
343 * Try to flush any pending writes to the file..
344 *
345 * NOTE! Because we own the page lock, there cannot
346 * be any new pending writes generated at this point
347 * for this page (other pages can be written to).
348 */
349 ret = nfs_wb_page(inode, page);
350 if (ret)
351 goto out_unlock;
352 if (PageUptodate(page))
353 goto out_unlock;
354
355 ret = -ESTALE;
356 if (NFS_STALE(inode))
357 goto out_unlock;
358
359 if (file == NULL) {
360 ret = -EBADF;
361 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
362 if (desc.ctx == NULL)
363 goto out_unlock;
364 } else
365 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
366
367 xchg(&desc.ctx->error, 0);
368 nfs_pageio_init_read(&desc.pgio, inode, false,
369 &nfs_async_read_completion_ops);
370
371 ret = readpage_async_filler(&desc, page);
372 if (ret)
373 goto out;
374
375 nfs_pageio_complete_read(&desc.pgio);
376 ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
377 if (!ret) {
378 ret = wait_on_page_locked_killable(page);
379 if (!PageUptodate(page) && !ret)
380 ret = xchg(&desc.ctx->error, 0);
381 }
382out:
383 put_nfs_open_context(desc.ctx);
384 trace_nfs_aop_readpage_done(inode, page, ret);
385 return ret;
386out_unlock:
387 unlock_page(page);
388 trace_nfs_aop_readpage_done(inode, page, ret);
389 return ret;
390}
391
392void nfs_readahead(struct readahead_control *ractl)
393{
394 unsigned int nr_pages = readahead_count(ractl);
395 struct file *file = ractl->file;
396 struct nfs_readdesc desc;
397 struct inode *inode = ractl->mapping->host;
398 struct page *page;
399 int ret;
400
401 trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
402 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
403
404 ret = -ESTALE;
405 if (NFS_STALE(inode))
406 goto out;
407
408 if (file == NULL) {
409 ret = -EBADF;
410 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
411 if (desc.ctx == NULL)
412 goto out;
413 } else
414 desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
415
416 nfs_pageio_init_read(&desc.pgio, inode, false,
417 &nfs_async_read_completion_ops);
418
419 while ((page = readahead_page(ractl)) != NULL) {
420 ret = readpage_async_filler(&desc, page);
421 put_page(page);
422 if (ret)
423 break;
424 }
425
426 nfs_pageio_complete_read(&desc.pgio);
427
428 put_nfs_open_context(desc.ctx);
429out:
430 trace_nfs_aop_readahead_done(inode, nr_pages, ret);
431}
432
433int __init nfs_init_readpagecache(void)
434{
435 nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
436 sizeof(struct nfs_pgio_header),
437 0, SLAB_HWCACHE_ALIGN,
438 NULL);
439 if (nfs_rdata_cachep == NULL)
440 return -ENOMEM;
441
442 return 0;
443}
444
445void nfs_destroy_readpagecache(void)
446{
447 kmem_cache_destroy(nfs_rdata_cachep);
448}
449
450static const struct nfs_rw_ops nfs_rw_read_ops = {
451 .rw_alloc_header = nfs_readhdr_alloc,
452 .rw_free_header = nfs_readhdr_free,
453 .rw_done = nfs_readpage_done,
454 .rw_result = nfs_readpage_result,
455 .rw_initiate = nfs_initiate_read,
456};