xref: /openbmc/linux/fs/nfs/fscache.c (revision 55b37d9c) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* NFS filesystem cache interface
3  *
4  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/init.h>
9 #include <linux/kernel.h>
10 #include <linux/sched.h>
11 #include <linux/mm.h>
12 #include <linux/nfs_fs.h>
13 #include <linux/nfs_fs_sb.h>
14 #include <linux/in6.h>
15 #include <linux/seq_file.h>
16 #include <linux/slab.h>
17 #include <linux/iversion.h>
18 #include <linux/xarray.h>
19 #include <linux/fscache.h>
20 #include <linux/netfs.h>
21 
22 #include "internal.h"
23 #include "iostat.h"
24 #include "fscache.h"
25 #include "nfstrace.h"
26 
27 #define NFS_MAX_KEY_LEN 1000
28 
29 static bool nfs_append_int(char *key, int *_len, unsigned long long x)
30 {
31 	if (*_len > NFS_MAX_KEY_LEN)
32 		return false;
33 	if (x == 0)
34 		key[(*_len)++] = ',';
35 	else
36 		*_len += sprintf(key + *_len, ",%llx", x);
37 	return true;
38 }
39 
40 /*
41  * Get the per-client index cookie for an NFS client if the appropriate mount
42  * flag was set
43  * - We always try and get an index cookie for the client, but get filehandle
44  *   cookies on a per-superblock basis, depending on the mount flags
45  */
46 static bool nfs_fscache_get_client_key(struct nfs_client *clp,
47 				       char *key, int *_len)
48 {
49 	const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
50 	const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
51 
52 	*_len += snprintf(key + *_len, NFS_MAX_KEY_LEN - *_len,
53 			  ",%u.%u,%x",
54 			  clp->rpc_ops->version,
55 			  clp->cl_minorversion,
56 			  clp->cl_addr.ss_family);
57 
58 	switch (clp->cl_addr.ss_family) {
59 	case AF_INET:
60 		if (!nfs_append_int(key, _len, sin->sin_port) ||
61 		    !nfs_append_int(key, _len, sin->sin_addr.s_addr))
62 			return false;
63 		return true;
64 
65 	case AF_INET6:
66 		if (!nfs_append_int(key, _len, sin6->sin6_port) ||
67 		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[0]) ||
68 		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[1]) ||
69 		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[2]) ||
70 		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[3]))
71 			return false;
72 		return true;
73 
74 	default:
75 		printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
76 		       clp->cl_addr.ss_family);
77 		return false;
78 	}
79 }
80 
81 /*
82  * Get the cache cookie for an NFS superblock.
83  *
84  * The default uniquifier is just an empty string, but it may be overridden
85  * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
86  * superblock across an automount point of some nature.
87  */
88 int nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
89 {
90 	struct fscache_volume *vcookie;
91 	struct nfs_server *nfss = NFS_SB(sb);
92 	unsigned int len = 3;
93 	char *key;
94 
95 	if (uniq) {
96 		nfss->fscache_uniq = kmemdup_nul(uniq, ulen, GFP_KERNEL);
97 		if (!nfss->fscache_uniq)
98 			return -ENOMEM;
99 	}
100 
101 	key = kmalloc(NFS_MAX_KEY_LEN + 24, GFP_KERNEL);
102 	if (!key)
103 		return -ENOMEM;
104 
105 	memcpy(key, "nfs", 3);
106 	if (!nfs_fscache_get_client_key(nfss->nfs_client, key, &len) ||
107 	    !nfs_append_int(key, &len, nfss->fsid.major) ||
108 	    !nfs_append_int(key, &len, nfss->fsid.minor) ||
109 	    !nfs_append_int(key, &len, sb->s_flags & NFS_SB_MASK) ||
110 	    !nfs_append_int(key, &len, nfss->flags) ||
111 	    !nfs_append_int(key, &len, nfss->rsize) ||
112 	    !nfs_append_int(key, &len, nfss->wsize) ||
113 	    !nfs_append_int(key, &len, nfss->acregmin) ||
114 	    !nfs_append_int(key, &len, nfss->acregmax) ||
115 	    !nfs_append_int(key, &len, nfss->acdirmin) ||
116 	    !nfs_append_int(key, &len, nfss->acdirmax) ||
117 	    !nfs_append_int(key, &len, nfss->client->cl_auth->au_flavor))
118 		goto out;
119 
120 	if (ulen > 0) {
121 		if (ulen > NFS_MAX_KEY_LEN - len)
122 			goto out;
123 		key[len++] = ',';
124 		memcpy(key + len, uniq, ulen);
125 		len += ulen;
126 	}
127 	key[len] = 0;
128 
129 	/* create a cache index for looking up filehandles */
130 	vcookie = fscache_acquire_volume(key,
131 					 NULL, /* preferred_cache */
132 					 NULL, 0 /* coherency_data */);
133 	if (IS_ERR(vcookie)) {
134 		if (vcookie != ERR_PTR(-EBUSY)) {
135 			kfree(key);
136 			return PTR_ERR(vcookie);
137 		}
138 		pr_err("NFS: Cache volume key already in use (%s)\n", key);
139 		vcookie = NULL;
140 	}
141 	nfss->fscache = vcookie;
142 
143 out:
144 	kfree(key);
145 	return 0;
146 }
147 
148 /*
149  * release a per-superblock cookie
150  */
151 void nfs_fscache_release_super_cookie(struct super_block *sb)
152 {
153 	struct nfs_server *nfss = NFS_SB(sb);
154 
155 	fscache_relinquish_volume(nfss->fscache, NULL, false);
156 	nfss->fscache = NULL;
157 	kfree(nfss->fscache_uniq);
158 }
159 
160 /*
161  * Initialise the per-inode cache cookie pointer for an NFS inode.
162  */
163 void nfs_fscache_init_inode(struct inode *inode)
164 {
165 	struct nfs_fscache_inode_auxdata auxdata;
166 	struct nfs_server *nfss = NFS_SERVER(inode);
167 	struct nfs_inode *nfsi = NFS_I(inode);
168 
169 	netfs_inode(inode)->cache = NULL;
170 	if (!(nfss->fscache && S_ISREG(inode->i_mode)))
171 		return;
172 
173 	nfs_fscache_update_auxdata(&auxdata, inode);
174 
175 	netfs_inode(inode)->cache = fscache_acquire_cookie(
176 					       nfss->fscache,
177 					       0,
178 					       nfsi->fh.data, /* index_key */
179 					       nfsi->fh.size,
180 					       &auxdata,      /* aux_data */
181 					       sizeof(auxdata),
182 					       i_size_read(inode));
183 }
184 
185 /*
186  * Release a per-inode cookie.
187  */
188 void nfs_fscache_clear_inode(struct inode *inode)
189 {
190 	fscache_relinquish_cookie(netfs_i_cookie(netfs_inode(inode)), false);
191 	netfs_inode(inode)->cache = NULL;
192 }
193 
194 /*
195  * Enable or disable caching for a file that is being opened as appropriate.
196  * The cookie is allocated when the inode is initialised, but is not enabled at
197  * that time.  Enablement is deferred to file-open time to avoid stat() and
198  * access() thrashing the cache.
199  *
200  * For now, with NFS, only regular files that are open read-only will be able
201  * to use the cache.
202  *
203  * We enable the cache for an inode if we open it read-only and it isn't
204  * currently open for writing.  We disable the cache if the inode is open
205  * write-only.
206  *
207  * The caller uses the file struct to pin i_writecount on the inode before
208  * calling us when a file is opened for writing, so we can make use of that.
209  *
210  * Note that this may be invoked multiple times in parallel by parallel
211  * nfs_open() functions.
212  */
213 void nfs_fscache_open_file(struct inode *inode, struct file *filp)
214 {
215 	struct nfs_fscache_inode_auxdata auxdata;
216 	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
217 	bool open_for_write = inode_is_open_for_write(inode);
218 
219 	if (!fscache_cookie_valid(cookie))
220 		return;
221 
222 	fscache_use_cookie(cookie, open_for_write);
223 	if (open_for_write) {
224 		nfs_fscache_update_auxdata(&auxdata, inode);
225 		fscache_invalidate(cookie, &auxdata, i_size_read(inode),
226 				   FSCACHE_INVAL_DIO_WRITE);
227 	}
228 }
229 EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
230 
231 void nfs_fscache_release_file(struct inode *inode, struct file *filp)
232 {
233 	struct nfs_fscache_inode_auxdata auxdata;
234 	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
235 	loff_t i_size = i_size_read(inode);
236 
237 	nfs_fscache_update_auxdata(&auxdata, inode);
238 	fscache_unuse_cookie(cookie, &auxdata, &i_size);
239 }
240 
241 int nfs_netfs_read_folio(struct file *file, struct folio *folio)
242 {
243 	if (!netfs_inode(folio_inode(folio))->cache)
244 		return -ENOBUFS;
245 
246 	return netfs_read_folio(file, folio);
247 }
248 
249 int nfs_netfs_readahead(struct readahead_control *ractl)
250 {
251 	struct inode *inode = ractl->mapping->host;
252 
253 	if (!netfs_inode(inode)->cache)
254 		return -ENOBUFS;
255 
256 	netfs_readahead(ractl);
257 	return 0;
258 }
259 
260 static atomic_t nfs_netfs_debug_id;
261 static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
262 {
263 	rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
264 	rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
265 
266 	return 0;
267 }
268 
269 static void nfs_netfs_free_request(struct netfs_io_request *rreq)
270 {
271 	put_nfs_open_context(rreq->netfs_priv);
272 }
273 
274 static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
275 {
276 	return fscache_begin_read_operation(&rreq->cache_resources,
277 					    netfs_i_cookie(netfs_inode(rreq->inode)));
278 }
279 
280 static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
281 {
282 	struct nfs_netfs_io_data *netfs;
283 
284 	netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
285 	if (!netfs)
286 		return NULL;
287 	netfs->sreq = sreq;
288 	refcount_set(&netfs->refcount, 1);
289 	return netfs;
290 }
291 
292 static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
293 {
294 	size_t	rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
295 
296 	sreq->len = min(sreq->len, rsize);
297 	return true;
298 }
299 
300 static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
301 {
302 	struct nfs_netfs_io_data	*netfs;
303 	struct nfs_pageio_descriptor	pgio;
304 	struct inode *inode = sreq->rreq->inode;
305 	struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
306 	struct page *page;
307 	int err;
308 	pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
309 	pgoff_t last = ((sreq->start + sreq->len -
310 			 sreq->transferred - 1) >> PAGE_SHIFT);
311 	XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
312 
313 	nfs_pageio_init_read(&pgio, inode, false,
314 			     &nfs_async_read_completion_ops);
315 
316 	netfs = nfs_netfs_alloc(sreq);
317 	if (!netfs)
318 		return netfs_subreq_terminated(sreq, -ENOMEM, false);
319 
320 	pgio.pg_netfs = netfs; /* used in completion */
321 
322 	xas_lock(&xas);
323 	xas_for_each(&xas, page, last) {
324 		/* nfs_read_add_folio() may schedule() due to pNFS layout and other RPCs  */
325 		xas_pause(&xas);
326 		xas_unlock(&xas);
327 		err = nfs_read_add_folio(&pgio, ctx, page_folio(page));
328 		if (err < 0) {
329 			netfs->error = err;
330 			goto out;
331 		}
332 		xas_lock(&xas);
333 	}
334 	xas_unlock(&xas);
335 out:
336 	nfs_pageio_complete_read(&pgio);
337 	nfs_netfs_put(netfs);
338 }
339 
340 void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr)
341 {
342 	struct nfs_netfs_io_data        *netfs = hdr->netfs;
343 
344 	if (!netfs)
345 		return;
346 
347 	nfs_netfs_get(netfs);
348 }
349 
350 int nfs_netfs_folio_unlock(struct folio *folio)
351 {
352 	struct inode *inode = folio_file_mapping(folio)->host;
353 
354 	/*
355 	 * If fscache is enabled, netfs will unlock pages.
356 	 */
357 	if (netfs_inode(inode)->cache)
358 		return 0;
359 
360 	return 1;
361 }
362 
363 void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
364 {
365 	struct nfs_netfs_io_data        *netfs = hdr->netfs;
366 	struct netfs_io_subrequest      *sreq;
367 
368 	if (!netfs)
369 		return;
370 
371 	sreq = netfs->sreq;
372 	if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
373 		__set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
374 
375 	if (hdr->error)
376 		netfs->error = hdr->error;
377 	else
378 		atomic64_add(hdr->res.count, &netfs->transferred);
379 
380 	nfs_netfs_put(netfs);
381 	hdr->netfs = NULL;
382 }
383 
384 const struct netfs_request_ops nfs_netfs_ops = {
385 	.init_request		= nfs_netfs_init_request,
386 	.free_request		= nfs_netfs_free_request,
387 	.begin_cache_operation	= nfs_netfs_begin_cache_operation,
388 	.issue_read		= nfs_netfs_issue_read,
389 	.clamp_length		= nfs_netfs_clamp_length
390 };
391