summaryrefslogtreecommitdiff
path: root/fs/nfs/fscache.c
blob: e3816eb53fb8d831b68c55f8929fd921a300122d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
/* NFS filesystem cache interface
 *
 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>
#include <linux/seq_file.h>

#include "internal.h"
#include "fscache.h"

#define NFSDBG_FACILITY		NFSDBG_FSCACHE

static struct rb_root nfs_fscache_keys = RB_ROOT;
static DEFINE_SPINLOCK(nfs_fscache_keys_lock);

/*
 * Get the per-client index cookie for an NFS client if the appropriate mount
 * flag was set
 * - We always try and get an index cookie for the client, but get filehandle
 *   cookies on a per-superblock basis, depending on the mount flags
 */
void nfs_fscache_get_client_cookie(struct nfs_client *clp)
{
	/* create a cache index for looking up filehandles */
	clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
					      &nfs_fscache_server_index_def,
					      clp);
	dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
		 clp, clp->fscache);
}

/*
 * Dispose of a per-client cookie
 */
void nfs_fscache_release_client_cookie(struct nfs_client *clp)
{
	dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
		 clp, clp->fscache);

	fscache_relinquish_cookie(clp->fscache, 0);
	clp->fscache = NULL;
}

/*
 * Get the cache cookie for an NFS superblock.  We have to handle
 * uniquification here because the cache doesn't do it for us.
 */
void nfs_fscache_get_super_cookie(struct super_block *sb,
				  struct nfs_parsed_mount_data *data)
{
	struct nfs_fscache_key *key, *xkey;
	struct nfs_server *nfss = NFS_SB(sb);
	struct rb_node **p, *parent;
	const char *uniq = data->fscache_uniq ?: "";
	int diff, ulen;

	ulen = strlen(uniq);
	key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
	if (!key)
		return;

	key->nfs_client = nfss->nfs_client;
	key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
	key->key.nfs_server.flags = nfss->flags;
	key->key.nfs_server.rsize = nfss->rsize;
	key->key.nfs_server.wsize = nfss->wsize;
	key->key.nfs_server.acregmin = nfss->acregmin;
	key->key.nfs_server.acregmax = nfss->acregmax;
	key->key.nfs_server.acdirmin = nfss->acdirmin;
	key->key.nfs_server.acdirmax = nfss->acdirmax;
	key->key.nfs_server.fsid = nfss->fsid;
	key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;

	key->key.uniq_len = ulen;
	memcpy(key->key.uniquifier, uniq, ulen);

	spin_lock(&nfs_fscache_keys_lock);
	p = &nfs_fscache_keys.rb_node;
	parent = NULL;
	while (*p) {
		parent = *p;
		xkey = rb_entry(parent, struct nfs_fscache_key, node);

		if (key->nfs_client < xkey->nfs_client)
			goto go_left;
		if (key->nfs_client > xkey->nfs_client)
			goto go_right;

		diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
		if (diff < 0)
			goto go_left;
		if (diff > 0)
			goto go_right;

		if (key->key.uniq_len == 0)
			goto non_unique;
		diff = memcmp(key->key.uniquifier,
			      xkey->key.uniquifier,
			      key->key.uniq_len);
		if (diff < 0)
			goto go_left;
		if (diff > 0)
			goto go_right;
		goto non_unique;

	go_left:
		p = &(*p)->rb_left;
		continue;
	go_right:
		p = &(*p)->rb_right;
	}

	rb_link_node(&key->node, parent, p);
	rb_insert_color(&key->node, &nfs_fscache_keys);
	spin_unlock(&nfs_fscache_keys_lock);
	nfss->fscache_key = key;

	/* create a cache index for looking up filehandles */
	nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
					       &nfs_fscache_super_index_def,
					       nfss);
	dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
		 nfss, nfss->fscache);
	return;

non_unique:
	spin_unlock(&nfs_fscache_keys_lock);
	kfree(key);
	nfss->fscache_key = NULL;
	nfss->fscache = NULL;
	printk(KERN_WARNING "NFS:"
	       " Cache request denied due to non-unique superblock keys\n");
}

/*
 * release a per-superblock cookie
 */
void nfs_fscache_release_super_cookie(struct super_block *sb)
{
	struct nfs_server *nfss = NFS_SB(sb);

	dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
		 nfss, nfss->fscache);

	fscache_relinquish_cookie(nfss->fscache, 0);
	nfss->fscache = NULL;

	if (nfss->fscache_key) {
		spin_lock(&nfs_fscache_keys_lock);
		rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
		spin_unlock(&nfs_fscache_keys_lock);
		kfree(nfss->fscache_key);
		nfss->fscache_key = NULL;
	}
}

/*
 * Initialise the per-inode cache cookie pointer for an NFS inode.
 */
void nfs_fscache_init_inode_cookie(struct inode *inode)
{
	NFS_I(inode)->fscache = NULL;
	if (S_ISREG(inode->i_mode))
		set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
}

/*
 * Get the per-inode cache cookie for an NFS inode.
 */
static void nfs_fscache_enable_inode_cookie(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	struct nfs_inode *nfsi = NFS_I(inode);

	if (nfsi->fscache || !NFS_FSCACHE(inode))
		return;

	if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
		nfsi->fscache = fscache_acquire_cookie(
			NFS_SB(sb)->fscache,
			&nfs_fscache_inode_object_def,
			nfsi);

		dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
			 sb, nfsi, nfsi->fscache);
	}
}

/*
 * Release a per-inode cookie.
 */
void nfs_fscache_release_inode_cookie(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);

	dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
		 nfsi, nfsi->fscache);

	fscache_relinquish_cookie(nfsi->fscache, 0);
	nfsi->fscache = NULL;
}

/*
 * Retire a per-inode cookie, destroying the data attached to it.
 */
void nfs_fscache_zap_inode_cookie(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);

	dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
		 nfsi, nfsi->fscache);

	fscache_relinquish_cookie(nfsi->fscache, 1);
	nfsi->fscache = NULL;
}

/*
 * Turn off the cache with regard to a per-inode cookie if opened for writing,
 * invalidating all the pages in the page cache relating to the associated
 * inode to clear the per-page caching.
 */
static void nfs_fscache_disable_inode_cookie(struct inode *inode)
{
	clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);

	if (NFS_I(inode)->fscache) {
		dfprintk(FSCACHE,
			 "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));

		/* Need to invalidate any mapped pages that were read in before
		 * turning off the cache.
		 */
		if (inode->i_mapping && inode->i_mapping->nrpages)
			invalidate_inode_pages2(inode->i_mapping);

		nfs_fscache_zap_inode_cookie(inode);
	}
}

/*
 * wait_on_bit() sleep function for uninterruptible waiting
 */
static int nfs_fscache_wait_bit(void *flags)
{
	schedule();
	return 0;
}

/*
 * Lock against someone else trying to also acquire or relinquish a cookie
 */
static inline void nfs_fscache_inode_lock(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);

	while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
		wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
			    nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
}

/*
 * Unlock cookie management lock
 */
static inline void nfs_fscache_inode_unlock(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);

	smp_mb__before_clear_bit();
	clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
	smp_mb__after_clear_bit();
	wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
}

/*
 * Decide if we should enable or disable local caching for this inode.
 * - For now, with NFS, only regular files that are open read-only will be able
 *   to use the cache.
 * - May be invoked multiple times in parallel by parallel nfs_open() functions.
 */
void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
{
	if (NFS_FSCACHE(inode)) {
		nfs_fscache_inode_lock(inode);
		if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
			nfs_fscache_disable_inode_cookie(inode);
		else
			nfs_fscache_enable_inode_cookie(inode);
		nfs_fscache_inode_unlock(inode);
	}
}

/*
 * Replace a per-inode cookie due to revalidation detecting a file having
 * changed on the server.
 */
void nfs_fscache_reset_inode_cookie(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_server *nfss = NFS_SERVER(inode);
	struct fscache_cookie *old = nfsi->fscache;

	nfs_fscache_inode_lock(inode);
	if (nfsi->fscache) {
		/* retire the current fscache cache and get a new one */
		fscache_relinquish_cookie(nfsi->fscache, 1);

		nfsi->fscache = fscache_acquire_cookie(
			nfss->nfs_client->fscache,
			&nfs_fscache_inode_object_def,
			nfsi);

		dfprintk(FSCACHE,
			 "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
			 nfss, nfsi, old, nfsi->fscache);
	}
	nfs_fscache_inode_unlock(inode);
}