xref: /openbmc/linux/fs/nfs/read.c (revision 71739da6)
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 
nfs_readhdr_alloc(void)39 static struct nfs_pgio_header *nfs_readhdr_alloc(void)
40 {
41 	struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
42 
43 	if (p)
44 		p->rw_mode = FMODE_READ;
45 	return p;
46 }
47 
nfs_readhdr_free(struct nfs_pgio_header * rhdr)48 static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
49 {
50 	if (rhdr->res.scratch != NULL)
51 		kfree(rhdr->res.scratch);
52 	kmem_cache_free(nfs_rdata_cachep, rhdr);
53 }
54 
nfs_return_empty_folio(struct folio * folio)55 static int nfs_return_empty_folio(struct folio *folio)
56 {
57 	folio_zero_segment(folio, 0, folio_size(folio));
58 	folio_mark_uptodate(folio);
59 	folio_unlock(folio);
60 	return 0;
61 }
62 
nfs_pageio_init_read(struct nfs_pageio_descriptor * pgio,struct inode * inode,bool force_mds,const struct nfs_pgio_completion_ops * compl_ops)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(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
75 			server->rsize, 0);
76 }
77 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
78 
nfs_pageio_complete_read(struct nfs_pageio_descriptor * pgio)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(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(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
91 	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
92 	nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
93 }
94 
95 
nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor * pgio)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(pgio->pg_inode)->rsize;
110 }
111 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
112 
nfs_read_alloc_scratch(struct nfs_pgio_header * hdr,size_t size)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 
nfs_readpage_release(struct nfs_page * req,int error)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(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 
nfs_page_group_set_uptodate(struct nfs_page * req)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(nfs_page_to_folio(req));
138 }
139 
nfs_read_completion(struct nfs_pgio_header * hdr)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(&hdr->pages)) {
148 		struct nfs_page *req = nfs_list_entry(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, 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, 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 
nfs_initiate_read(struct nfs_pgio_header * hdr,struct rpc_message * msg,const struct nfs_rpc_ops * rpc_ops,struct rpc_task_setup * task_setup_data,int how)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
nfs_async_read_error(struct list_head * head,int error)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->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  */
nfs_readpage_done(struct rpc_task * task,struct nfs_pgio_header * hdr,struct inode * inode)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, NFSIOS_SERVERREADBYTES, 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 
nfs_readpage_retry(struct rpc_task * task,struct nfs_pgio_header * hdr)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(hdr->inode, 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, -EIO, 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 
nfs_readpage_result(struct rpc_task * task,struct nfs_pgio_header * hdr)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(NFS_IOHDR_EOF, &hdr->flags);
281 			clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
282 		}
283 	} else if (hdr->res.count < hdr->args.count)
284 		nfs_readpage_retry(task, hdr);
285 }
286 
nfs_read_add_folio(struct nfs_pageio_descriptor * pgio,struct nfs_open_context * ctx,struct folio * folio)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, 0, aligned_len);
306 	if (IS_ERR(new)) {
307 		error = PTR_ERR(new);
308 		if (nfs_netfs_folio_unlock(folio))
309 			folio_unlock(folio);
310 		goto out;
311 	}
312 
313 	if (len < fsize)
314 		folio_zero_segment(folio, len, fsize);
315 	if (!nfs_pageio_add_request(pgio, new)) {
316 		nfs_list_remove_request(new);
317 		error = pgio->pg_error;
318 		nfs_readpage_release(new, error);
319 		goto out;
320 	}
321 	return 0;
322 out:
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  */
nfs_read_folio(struct file * file,struct folio * folio)332 int nfs_read_folio(struct file *file, struct folio *folio)
333 {
334 	struct inode *inode = file_inode(file);
335 	struct nfs_pageio_descriptor pgio;
336 	struct nfs_open_context *ctx;
337 	int ret;
338 
339 	trace_nfs_aop_readpage(inode, folio);
340 	nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
341 	task_io_account_read(folio_size(folio));
342 
343 	/*
344 	 * Try to flush any pending writes to the file..
345 	 *
346 	 * NOTE! Because we own the folio lock, there cannot
347 	 * be any new pending writes generated at this point
348 	 * for this folio (other folios can be written to).
349 	 */
350 	ret = nfs_wb_folio(inode, folio);
351 	if (ret)
352 		goto out_unlock;
353 	if (folio_test_uptodate(folio))
354 		goto out_unlock;
355 
356 	ret = -ESTALE;
357 	if (NFS_STALE(inode))
358 		goto out_unlock;
359 
360 	ret = nfs_netfs_read_folio(file, folio);
361 	if (!ret)
362 		goto out;
363 
364 	ctx = get_nfs_open_context(nfs_file_open_context(file));
365 
366 	xchg(&ctx->error, 0);
367 	nfs_pageio_init_read(&pgio, inode, false,
368 			     &nfs_async_read_completion_ops);
369 
370 	ret = nfs_read_add_folio(&pgio, ctx, folio);
371 	if (ret)
372 		goto out_put;
373 
374 	nfs_pageio_complete_read(&pgio);
375 	ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
376 	if (!ret) {
377 		ret = folio_wait_locked_killable(folio);
378 		if (!folio_test_uptodate(folio) && !ret)
379 			ret = xchg(&ctx->error, 0);
380 	}
381 out_put:
382 	put_nfs_open_context(ctx);
383 out:
384 	trace_nfs_aop_readpage_done(inode, folio, ret);
385 	return ret;
386 out_unlock:
387 	folio_unlock(folio);
388 	goto out;
389 }
390 
nfs_readahead(struct readahead_control * ractl)391 void nfs_readahead(struct readahead_control *ractl)
392 {
393 	struct nfs_pageio_descriptor pgio;
394 	struct nfs_open_context *ctx;
395 	unsigned int nr_pages = readahead_count(ractl);
396 	struct file *file = ractl->file;
397 	struct inode *inode = ractl->mapping->host;
398 	struct folio *folio;
399 	int ret;
400 
401 	trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
402 	nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
403 	task_io_account_read(readahead_length(ractl));
404 
405 	ret = -ESTALE;
406 	if (NFS_STALE(inode))
407 		goto out;
408 
409 	ret = nfs_netfs_readahead(ractl);
410 	if (!ret)
411 		goto out;
412 
413 	if (file == NULL) {
414 		ret = -EBADF;
415 		ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
416 		if (ctx == NULL)
417 			goto out;
418 	} else
419 		ctx = get_nfs_open_context(nfs_file_open_context(file));
420 
421 	nfs_pageio_init_read(&pgio, inode, false,
422 			     &nfs_async_read_completion_ops);
423 
424 	while ((folio = readahead_folio(ractl)) != NULL) {
425 		ret = nfs_read_add_folio(&pgio, ctx, folio);
426 		if (ret)
427 			break;
428 	}
429 
430 	nfs_pageio_complete_read(&pgio);
431 
432 	put_nfs_open_context(ctx);
433 out:
434 	trace_nfs_aop_readahead_done(inode, nr_pages, ret);
435 }
436 
nfs_init_readpagecache(void)437 int __init nfs_init_readpagecache(void)
438 {
439 	nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
440 					     sizeof(struct nfs_pgio_header),
441 					     0, SLAB_HWCACHE_ALIGN,
442 					     NULL);
443 	if (nfs_rdata_cachep == NULL)
444 		return -ENOMEM;
445 
446 	return 0;
447 }
448 
nfs_destroy_readpagecache(void)449 void nfs_destroy_readpagecache(void)
450 {
451 	kmem_cache_destroy(nfs_rdata_cachep);
452 }
453 
454 static const struct nfs_rw_ops nfs_rw_read_ops = {
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 };
461