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/task_io_accounting_ops.h> |
19 | #include <linux/pagemap.h> |
20 | #include <linux/sunrpc/clnt.h> |
21 | #include <linux/nfs_fs.h> |
22 | #include <linux/nfs_page.h> |
23 | #include <linux/module.h> |
24 | |
25 | #include "nfs4_fs.h" |
26 | #include "internal.h" |
27 | #include "iostat.h" |
28 | #include "fscache.h" |
29 | #include "pnfs.h" |
30 | #include "nfstrace.h" |
31 | |
32 | #define NFSDBG_FACILITY NFSDBG_PAGECACHE |
33 | |
34 | const struct nfs_pgio_completion_ops nfs_async_read_completion_ops; |
35 | static const struct nfs_rw_ops nfs_rw_read_ops; |
36 | |
37 | static struct kmem_cache *nfs_rdata_cachep; |
38 | |
39 | static struct nfs_pgio_header *nfs_readhdr_alloc(void) |
40 | { |
41 | struct nfs_pgio_header *p = kmem_cache_zalloc(k: nfs_rdata_cachep, GFP_KERNEL); |
42 | |
43 | if (p) |
44 | p->rw_mode = FMODE_READ; |
45 | return p; |
46 | } |
47 | |
48 | static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) |
49 | { |
50 | if (rhdr->res.scratch != NULL) |
51 | kfree(objp: rhdr->res.scratch); |
52 | kmem_cache_free(s: nfs_rdata_cachep, objp: rhdr); |
53 | } |
54 | |
55 | static int nfs_return_empty_folio(struct folio *folio) |
56 | { |
57 | folio_zero_segment(folio, start: 0, xend: folio_size(folio)); |
58 | folio_mark_uptodate(folio); |
59 | folio_unlock(folio); |
60 | return 0; |
61 | } |
62 | |
63 | void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, |
64 | struct inode *inode, bool force_mds, |
65 | const struct nfs_pgio_completion_ops *compl_ops) |
66 | { |
67 | struct nfs_server *server = NFS_SERVER(inode); |
68 | const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops; |
69 | |
70 | #ifdef CONFIG_NFS_V4_1 |
71 | if (server->pnfs_curr_ld && !force_mds) |
72 | pg_ops = server->pnfs_curr_ld->pg_read_ops; |
73 | #endif |
74 | nfs_pageio_init(desc: pgio, inode, pg_ops, compl_ops, rw_ops: &nfs_rw_read_ops, |
75 | bsize: server->rsize, how: 0); |
76 | } |
77 | EXPORT_SYMBOL_GPL(nfs_pageio_init_read); |
78 | |
79 | void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio) |
80 | { |
81 | struct nfs_pgio_mirror *pgm; |
82 | unsigned long npages; |
83 | |
84 | nfs_pageio_complete(desc: pgio); |
85 | |
86 | /* It doesn't make sense to do mirrored reads! */ |
87 | WARN_ON_ONCE(pgio->pg_mirror_count != 1); |
88 | |
89 | pgm = &pgio->pg_mirrors[0]; |
90 | NFS_I(inode: pgio->pg_inode)->read_io += pgm->pg_bytes_written; |
91 | npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT; |
92 | nfs_add_stats(inode: pgio->pg_inode, stat: NFSIOS_READPAGES, addend: npages); |
93 | } |
94 | |
95 | |
96 | void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) |
97 | { |
98 | struct nfs_pgio_mirror *mirror; |
99 | |
100 | if (pgio->pg_ops && pgio->pg_ops->pg_cleanup) |
101 | pgio->pg_ops->pg_cleanup(pgio); |
102 | |
103 | pgio->pg_ops = &nfs_pgio_rw_ops; |
104 | |
105 | /* read path should never have more than one mirror */ |
106 | WARN_ON_ONCE(pgio->pg_mirror_count != 1); |
107 | |
108 | mirror = &pgio->pg_mirrors[0]; |
109 | mirror->pg_bsize = NFS_SERVER(inode: pgio->pg_inode)->rsize; |
110 | } |
111 | EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); |
112 | |
113 | bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size) |
114 | { |
115 | WARN_ON(hdr->res.scratch != NULL); |
116 | hdr->res.scratch = kmalloc(size, GFP_KERNEL); |
117 | return hdr->res.scratch != NULL; |
118 | } |
119 | EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch); |
120 | |
121 | static void nfs_readpage_release(struct nfs_page *req, int error) |
122 | { |
123 | struct folio *folio = nfs_page_to_folio(req); |
124 | |
125 | if (nfs_error_is_fatal_on_server(err: error) && error != -ETIMEDOUT) |
126 | folio_set_error(folio); |
127 | if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) |
128 | if (nfs_netfs_folio_unlock(folio)) |
129 | folio_unlock(folio); |
130 | |
131 | nfs_release_request(req); |
132 | } |
133 | |
134 | static void nfs_page_group_set_uptodate(struct nfs_page *req) |
135 | { |
136 | if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) |
137 | folio_mark_uptodate(folio: nfs_page_to_folio(req)); |
138 | } |
139 | |
140 | static void nfs_read_completion(struct nfs_pgio_header *hdr) |
141 | { |
142 | unsigned long bytes = 0; |
143 | int error; |
144 | |
145 | if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) |
146 | goto out; |
147 | while (!list_empty(head: &hdr->pages)) { |
148 | struct nfs_page *req = nfs_list_entry(head: hdr->pages.next); |
149 | struct folio *folio = nfs_page_to_folio(req); |
150 | unsigned long start = req->wb_pgbase; |
151 | unsigned long end = req->wb_pgbase + req->wb_bytes; |
152 | |
153 | if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { |
154 | /* note: regions of the page not covered by a |
155 | * request are zeroed in nfs_read_add_folio |
156 | */ |
157 | if (bytes > hdr->good_bytes) { |
158 | /* nothing in this request was good, so zero |
159 | * the full extent of the request */ |
160 | folio_zero_segment(folio, start, xend: 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 | folio_zero_segment(folio, start, xend: 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 | } |
184 | nfs_netfs_read_completion(hdr); |
185 | |
186 | out: |
187 | hdr->release(hdr); |
188 | } |
189 | |
190 | static void nfs_initiate_read(struct nfs_pgio_header *hdr, |
191 | struct rpc_message *msg, |
192 | const struct nfs_rpc_ops *rpc_ops, |
193 | struct rpc_task_setup *task_setup_data, int how) |
194 | { |
195 | rpc_ops->read_setup(hdr, msg); |
196 | nfs_netfs_initiate_read(hdr); |
197 | trace_nfs_initiate_read(hdr); |
198 | } |
199 | |
200 | static void |
201 | nfs_async_read_error(struct list_head *head, int error) |
202 | { |
203 | struct nfs_page *req; |
204 | |
205 | while (!list_empty(head)) { |
206 | req = nfs_list_entry(head: head->next); |
207 | nfs_list_remove_request(req); |
208 | nfs_readpage_release(req, error); |
209 | } |
210 | } |
211 | |
212 | const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { |
213 | .error_cleanup = nfs_async_read_error, |
214 | .completion = nfs_read_completion, |
215 | }; |
216 | |
217 | /* |
218 | * This is the callback from RPC telling us whether a reply was |
219 | * received or some error occurred (timeout or socket shutdown). |
220 | */ |
221 | static int nfs_readpage_done(struct rpc_task *task, |
222 | struct nfs_pgio_header *hdr, |
223 | struct inode *inode) |
224 | { |
225 | int status = NFS_PROTO(inode)->read_done(task, hdr); |
226 | if (status != 0) |
227 | return status; |
228 | |
229 | nfs_add_stats(inode, stat: NFSIOS_SERVERREADBYTES, addend: hdr->res.count); |
230 | trace_nfs_readpage_done(task, hdr); |
231 | |
232 | if (task->tk_status == -ESTALE) { |
233 | nfs_set_inode_stale(inode); |
234 | nfs_mark_for_revalidate(inode); |
235 | } |
236 | return 0; |
237 | } |
238 | |
239 | static 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(inode: hdr->inode, stat: NFSIOS_SHORTREAD); |
247 | trace_nfs_readpage_short(task, hdr); |
248 | |
249 | /* Has the server at least made some progress? */ |
250 | if (resp->count == 0) { |
251 | nfs_set_pgio_error(hdr, error: -EIO, pos: argp->offset); |
252 | return; |
253 | } |
254 | |
255 | /* For non rpc-based layout drivers, retry-through-MDS */ |
256 | if (!task->tk_ops) { |
257 | hdr->pnfs_error = -EAGAIN; |
258 | return; |
259 | } |
260 | |
261 | /* Yes, so retry the read at the end of the hdr */ |
262 | hdr->mds_offset += resp->count; |
263 | argp->offset += resp->count; |
264 | argp->pgbase += resp->count; |
265 | argp->count -= resp->count; |
266 | resp->count = 0; |
267 | resp->eof = 0; |
268 | rpc_restart_call_prepare(task); |
269 | } |
270 | |
271 | static void nfs_readpage_result(struct rpc_task *task, |
272 | struct nfs_pgio_header *hdr) |
273 | { |
274 | if (hdr->res.eof) { |
275 | loff_t pos = hdr->args.offset + hdr->res.count; |
276 | unsigned int new = pos - hdr->io_start; |
277 | |
278 | if (hdr->good_bytes > new) { |
279 | hdr->good_bytes = new; |
280 | set_bit(nr: NFS_IOHDR_EOF, addr: &hdr->flags); |
281 | clear_bit(nr: NFS_IOHDR_ERROR, addr: &hdr->flags); |
282 | } |
283 | } else if (hdr->res.count < hdr->args.count) |
284 | nfs_readpage_retry(task, hdr); |
285 | } |
286 | |
287 | int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio, |
288 | struct nfs_open_context *ctx, |
289 | struct folio *folio) |
290 | { |
291 | struct inode *inode = folio_file_mapping(folio)->host; |
292 | struct nfs_server *server = NFS_SERVER(inode); |
293 | size_t fsize = folio_size(folio); |
294 | unsigned int rsize = server->rsize; |
295 | struct nfs_page *new; |
296 | unsigned int len, aligned_len; |
297 | int error; |
298 | |
299 | len = nfs_folio_length(folio); |
300 | if (len == 0) |
301 | return nfs_return_empty_folio(folio); |
302 | |
303 | aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize); |
304 | |
305 | new = nfs_page_create_from_folio(ctx, folio, offset: 0, count: aligned_len); |
306 | if (IS_ERR(ptr: new)) { |
307 | error = PTR_ERR(ptr: new); |
308 | goto out; |
309 | } |
310 | |
311 | if (len < fsize) |
312 | folio_zero_segment(folio, start: len, xend: fsize); |
313 | if (!nfs_pageio_add_request(pgio, new)) { |
314 | nfs_list_remove_request(req: new); |
315 | error = pgio->pg_error; |
316 | nfs_readpage_release(req: new, error); |
317 | goto out; |
318 | } |
319 | return 0; |
320 | out: |
321 | return error; |
322 | } |
323 | |
324 | /* |
325 | * Read a page over NFS. |
326 | * We read the page synchronously in the following case: |
327 | * - The error flag is set for this page. This happens only when a |
328 | * previous async read operation failed. |
329 | */ |
330 | int nfs_read_folio(struct file *file, struct folio *folio) |
331 | { |
332 | struct inode *inode = file_inode(f: file); |
333 | struct nfs_pageio_descriptor pgio; |
334 | struct nfs_open_context *ctx; |
335 | int ret; |
336 | |
337 | trace_nfs_aop_readpage(inode, folio); |
338 | nfs_inc_stats(inode, stat: NFSIOS_VFSREADPAGE); |
339 | task_io_account_read(bytes: folio_size(folio)); |
340 | |
341 | /* |
342 | * Try to flush any pending writes to the file.. |
343 | * |
344 | * NOTE! Because we own the folio lock, there cannot |
345 | * be any new pending writes generated at this point |
346 | * for this folio (other folios can be written to). |
347 | */ |
348 | ret = nfs_wb_folio(inode, folio); |
349 | if (ret) |
350 | goto out_unlock; |
351 | if (folio_test_uptodate(folio)) |
352 | goto out_unlock; |
353 | |
354 | ret = -ESTALE; |
355 | if (NFS_STALE(inode)) |
356 | goto out_unlock; |
357 | |
358 | ret = nfs_netfs_read_folio(file, folio); |
359 | if (!ret) |
360 | goto out; |
361 | |
362 | ctx = get_nfs_open_context(ctx: nfs_file_open_context(filp: file)); |
363 | |
364 | xchg(&ctx->error, 0); |
365 | nfs_pageio_init_read(&pgio, inode, false, |
366 | &nfs_async_read_completion_ops); |
367 | |
368 | ret = nfs_read_add_folio(pgio: &pgio, ctx, folio); |
369 | if (ret) |
370 | goto out_put; |
371 | |
372 | nfs_pageio_complete_read(pgio: &pgio); |
373 | ret = pgio.pg_error < 0 ? pgio.pg_error : 0; |
374 | if (!ret) { |
375 | ret = folio_wait_locked_killable(folio); |
376 | if (!folio_test_uptodate(folio) && !ret) |
377 | ret = xchg(&ctx->error, 0); |
378 | } |
379 | out_put: |
380 | put_nfs_open_context(ctx); |
381 | out: |
382 | trace_nfs_aop_readpage_done(inode, folio, ret); |
383 | return ret; |
384 | out_unlock: |
385 | folio_unlock(folio); |
386 | goto out; |
387 | } |
388 | |
389 | void nfs_readahead(struct readahead_control *ractl) |
390 | { |
391 | struct nfs_pageio_descriptor pgio; |
392 | struct nfs_open_context *ctx; |
393 | unsigned int nr_pages = readahead_count(rac: ractl); |
394 | struct file *file = ractl->file; |
395 | struct inode *inode = ractl->mapping->host; |
396 | struct folio *folio; |
397 | int ret; |
398 | |
399 | trace_nfs_aop_readahead(inode, pos: readahead_pos(rac: ractl), nr_pages); |
400 | nfs_inc_stats(inode, stat: NFSIOS_VFSREADPAGES); |
401 | task_io_account_read(bytes: readahead_length(rac: ractl)); |
402 | |
403 | ret = -ESTALE; |
404 | if (NFS_STALE(inode)) |
405 | goto out; |
406 | |
407 | ret = nfs_netfs_readahead(ractl); |
408 | if (!ret) |
409 | goto out; |
410 | |
411 | if (file == NULL) { |
412 | ret = -EBADF; |
413 | ctx = nfs_find_open_context(inode, NULL, FMODE_READ); |
414 | if (ctx == NULL) |
415 | goto out; |
416 | } else |
417 | ctx = get_nfs_open_context(ctx: nfs_file_open_context(filp: file)); |
418 | |
419 | nfs_pageio_init_read(&pgio, inode, false, |
420 | &nfs_async_read_completion_ops); |
421 | |
422 | while ((folio = readahead_folio(ractl)) != NULL) { |
423 | ret = nfs_read_add_folio(pgio: &pgio, ctx, folio); |
424 | if (ret) |
425 | break; |
426 | } |
427 | |
428 | nfs_pageio_complete_read(pgio: &pgio); |
429 | |
430 | put_nfs_open_context(ctx); |
431 | out: |
432 | trace_nfs_aop_readahead_done(inode, nr_pages, ret); |
433 | } |
434 | |
435 | int __init nfs_init_readpagecache(void) |
436 | { |
437 | nfs_rdata_cachep = kmem_cache_create(name: "nfs_read_data" , |
438 | size: sizeof(struct nfs_pgio_header), |
439 | align: 0, SLAB_HWCACHE_ALIGN, |
440 | NULL); |
441 | if (nfs_rdata_cachep == NULL) |
442 | return -ENOMEM; |
443 | |
444 | return 0; |
445 | } |
446 | |
447 | void nfs_destroy_readpagecache(void) |
448 | { |
449 | kmem_cache_destroy(s: nfs_rdata_cachep); |
450 | } |
451 | |
452 | static const struct nfs_rw_ops nfs_rw_read_ops = { |
453 | .rw_alloc_header = nfs_readhdr_alloc, |
454 | .rw_free_header = nfs_readhdr_free, |
455 | .rw_done = nfs_readpage_done, |
456 | .rw_result = nfs_readpage_result, |
457 | .rw_initiate = nfs_initiate_read, |
458 | }; |
459 | |