aboutsummaryrefslogblamecommitdiffstats
path: root/fs/9p/cache.c
blob: 51c94e26a346f1de790e4f3cac3e039d097c5494 (plain) (tree)
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
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474

























































































































































































































































































































































































































































































                                                                               
/*
 * V9FS cache definitions.
 *
 *  Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/jiffies.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <net/9p/9p.h>

#include "v9fs.h"
#include "cache.h"

#define CACHETAG_LEN  11

struct kmem_cache *vcookie_cache;

struct fscache_netfs v9fs_cache_netfs = {
	.name 		= "9p",
	.version 	= 0,
};

static void init_once(void *foo)
{
	struct v9fs_cookie *vcookie = (struct v9fs_cookie *) foo;
	vcookie->fscache = NULL;
	vcookie->qid = NULL;
	inode_init_once(&vcookie->inode);
}

/**
 * v9fs_init_vcookiecache - initialize a cache for vcookies to maintain
 *			    vcookie to inode mapping
 *
 * Returns 0 on success.
 */

static int v9fs_init_vcookiecache(void)
{
	vcookie_cache = kmem_cache_create("vcookie_cache",
					  sizeof(struct v9fs_cookie),
					  0, (SLAB_RECLAIM_ACCOUNT|
					      SLAB_MEM_SPREAD),
					  init_once);
	if (!vcookie_cache)
		return -ENOMEM;

	return 0;
}

/**
 * v9fs_destroy_vcookiecache - destroy the cache of vcookies
 *
 */

static void v9fs_destroy_vcookiecache(void)
{
	kmem_cache_destroy(vcookie_cache);
}

int __v9fs_cache_register(void)
{
	int ret;
	ret = v9fs_init_vcookiecache();
	if (ret < 0)
		return ret;

	return fscache_register_netfs(&v9fs_cache_netfs);
}

void __v9fs_cache_unregister(void)
{
	v9fs_destroy_vcookiecache();
	fscache_unregister_netfs(&v9fs_cache_netfs);
}

/**
 * v9fs_random_cachetag - Generate a random tag to be associated
 *			  with a new cache session.
 *
 * The value of jiffies is used for a fairly randomly cache tag.
 */

static
int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
{
	v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
	if (!v9ses->cachetag)
		return -ENOMEM;

	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
}

static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
					   void *buffer, uint16_t bufmax)
{
	struct v9fs_session_info *v9ses;
	uint16_t klen = 0;

	v9ses = (struct v9fs_session_info *)cookie_netfs_data;
	P9_DPRINTK(P9_DEBUG_FSC, "session %p buf %p size %u", v9ses,
		   buffer, bufmax);

	if (v9ses->cachetag)
		klen = strlen(v9ses->cachetag);

	if (klen > bufmax)
		return 0;

	memcpy(buffer, v9ses->cachetag, klen);
	P9_DPRINTK(P9_DEBUG_FSC, "cache session tag %s", v9ses->cachetag);
	return klen;
}

const struct fscache_cookie_def v9fs_cache_session_index_def = {
	.name 		= "9P.session",
	.type 		= FSCACHE_COOKIE_TYPE_INDEX,
	.get_key 	= v9fs_cache_session_get_key,
};

void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
{
	/* If no cache session tag was specified, we generate a random one. */
	if (!v9ses->cachetag)
		v9fs_random_cachetag(v9ses);

	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
						&v9fs_cache_session_index_def,
						v9ses);
	P9_DPRINTK(P9_DEBUG_FSC, "session %p get cookie %p", v9ses,
		   v9ses->fscache);
}

void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
{
	P9_DPRINTK(P9_DEBUG_FSC, "session %p put cookie %p", v9ses,
		   v9ses->fscache);
	fscache_relinquish_cookie(v9ses->fscache, 0);
	v9ses->fscache = NULL;
}


static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
					 void *buffer, uint16_t bufmax)
{
	const struct v9fs_cookie *vcookie = cookie_netfs_data;
	memcpy(buffer, &vcookie->qid->path, sizeof(vcookie->qid->path));

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get key %llu", &vcookie->inode,
		   vcookie->qid->path);
	return sizeof(vcookie->qid->path);
}

static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
				      uint64_t *size)
{
	const struct v9fs_cookie *vcookie = cookie_netfs_data;
	*size = i_size_read(&vcookie->inode);

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get attr %llu", &vcookie->inode,
		   *size);
}

static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
					 void *buffer, uint16_t buflen)
{
	const struct v9fs_cookie *vcookie = cookie_netfs_data;
	memcpy(buffer, &vcookie->qid->version, sizeof(vcookie->qid->version));

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get aux %u", &vcookie->inode,
		   vcookie->qid->version);
	return sizeof(vcookie->qid->version);
}

static enum
fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
					    const void *buffer,
					    uint16_t buflen)
{
	const struct v9fs_cookie *vcookie = cookie_netfs_data;

	if (buflen != sizeof(vcookie->qid->version))
		return FSCACHE_CHECKAUX_OBSOLETE;

	if (memcmp(buffer, &vcookie->qid->version,
		   sizeof(vcookie->qid->version)))
		return FSCACHE_CHECKAUX_OBSOLETE;

	return FSCACHE_CHECKAUX_OKAY;
}

static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
{
	struct v9fs_cookie *vcookie = cookie_netfs_data;
	struct pagevec pvec;
	pgoff_t first;
	int loop, nr_pages;

	pagevec_init(&pvec, 0);
	first = 0;

	for (;;) {
		nr_pages = pagevec_lookup(&pvec, vcookie->inode.i_mapping,
					  first,
					  PAGEVEC_SIZE - pagevec_count(&pvec));
		if (!nr_pages)
			break;

		for (loop = 0; loop < nr_pages; loop++)
			ClearPageFsCache(pvec.pages[loop]);

		first = pvec.pages[nr_pages - 1]->index + 1;

		pvec.nr = nr_pages;
		pagevec_release(&pvec);
		cond_resched();
	}
}

const struct fscache_cookie_def v9fs_cache_inode_index_def = {
	.name		= "9p.inode",
	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
	.get_key	= v9fs_cache_inode_get_key,
	.get_attr	= v9fs_cache_inode_get_attr,
	.get_aux	= v9fs_cache_inode_get_aux,
	.check_aux	= v9fs_cache_inode_check_aux,
	.now_uncached	= v9fs_cache_inode_now_uncached,
};

void v9fs_cache_inode_get_cookie(struct inode *inode)
{
	struct v9fs_cookie *vcookie;
	struct v9fs_session_info *v9ses;

	if (!S_ISREG(inode->i_mode))
		return;

	vcookie = v9fs_inode2cookie(inode);
	if (vcookie->fscache)
		return;

	v9ses = v9fs_inode2v9ses(inode);
	vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
						  &v9fs_cache_inode_index_def,
						  vcookie);

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get cookie %p", inode,
		   vcookie->fscache);
}

void v9fs_cache_inode_put_cookie(struct inode *inode)
{
	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	if (!vcookie->fscache)
		return;
	P9_DPRINTK(P9_DEBUG_FSC, "inode %p put cookie %p", inode,
		   vcookie->fscache);

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

void v9fs_cache_inode_flush_cookie(struct inode *inode)
{
	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	if (!vcookie->fscache)
		return;
	P9_DPRINTK(P9_DEBUG_FSC, "inode %p flush cookie %p", inode,
		   vcookie->fscache);

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

void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
{
	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
	struct p9_fid *fid;

	if (!vcookie->fscache)
		return;

	spin_lock(&vcookie->lock);
	fid = filp->private_data;
	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
		v9fs_cache_inode_flush_cookie(inode);
	else
		v9fs_cache_inode_get_cookie(inode);

	spin_unlock(&vcookie->lock);
}

void v9fs_cache_inode_reset_cookie(struct inode *inode)
{
	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
	struct v9fs_session_info *v9ses;
	struct fscache_cookie *old;

	if (!vcookie->fscache)
		return;

	old = vcookie->fscache;

	spin_lock(&vcookie->lock);
	fscache_relinquish_cookie(vcookie->fscache, 1);

	v9ses = v9fs_inode2v9ses(inode);
	vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
						  &v9fs_cache_inode_index_def,
						  vcookie);

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p",
		   inode, old, vcookie->fscache);

	spin_unlock(&vcookie->lock);
}

int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
{
	struct inode *inode = page->mapping->host;
	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	BUG_ON(!vcookie->fscache);

	if (PageFsCache(page)) {
		if (fscache_check_page_write(vcookie->fscache, page)) {
			if (!(gfp & __GFP_WAIT))
				return 0;
			fscache_wait_on_page_write(vcookie->fscache, page);
		}

		fscache_uncache_page(vcookie->fscache, page);
		ClearPageFsCache(page);
	}

	return 1;
}

void __v9fs_fscache_invalidate_page(struct page *page)
{
	struct inode *inode = page->mapping->host;
	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	BUG_ON(!vcookie->fscache);

	if (PageFsCache(page)) {
		fscache_wait_on_page_write(vcookie->fscache, page);
		BUG_ON(!PageLocked(page));
		fscache_uncache_page(vcookie->fscache, page);
		ClearPageFsCache(page);
	}
}

static void v9fs_vfs_readpage_complete(struct page *page, void *data,
				       int error)
{
	if (!error)
		SetPageUptodate(page);

	unlock_page(page);
}

/**
 * __v9fs_readpage_from_fscache - read a page from cache
 *
 * Returns 0 if the pages are in cache and a BIO is submitted,
 * 1 if the pages are not in cache and -error otherwise.
 */

int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
{
	int ret;
	const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
	if (!vcookie->fscache)
		return -ENOBUFS;

	ret = fscache_read_or_alloc_page(vcookie->fscache,
					 page,
					 v9fs_vfs_readpage_complete,
					 NULL,
					 GFP_KERNEL);
	switch (ret) {
	case -ENOBUFS:
	case -ENODATA:
		P9_DPRINTK(P9_DEBUG_FSC, "page/inode not in cache %d", ret);
		return 1;
	case 0:
		P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
		return ret;
	default:
		P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
		return ret;
	}
}

/**
 * __v9fs_readpages_from_fscache - read multiple pages from cache
 *
 * Returns 0 if the pages are in cache and a BIO is submitted,
 * 1 if the pages are not in cache and -error otherwise.
 */

int __v9fs_readpages_from_fscache(struct inode *inode,
				  struct address_space *mapping,
				  struct list_head *pages,
				  unsigned *nr_pages)
{
	int ret;
	const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p pages %u", inode, *nr_pages);
	if (!vcookie->fscache)
		return -ENOBUFS;

	ret = fscache_read_or_alloc_pages(vcookie->fscache,
					  mapping, pages, nr_pages,
					  v9fs_vfs_readpage_complete,
					  NULL,
					  mapping_gfp_mask(mapping));
	switch (ret) {
	case -ENOBUFS:
	case -ENODATA:
		P9_DPRINTK(P9_DEBUG_FSC, "pages/inodes not in cache %d", ret);
		return 1;
	case 0:
		BUG_ON(!list_empty(pages));
		BUG_ON(*nr_pages != 0);
		P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
		return ret;
	default:
		P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
		return ret;
	}
}

/**
 * __v9fs_readpage_to_fscache - write a page to the cache
 *
 */

void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
{
	int ret;
	const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
	ret = fscache_write_page(vcookie->fscache, page, GFP_KERNEL);
	P9_DPRINTK(P9_DEBUG_FSC, "ret =  %d", ret);
	if (ret != 0)
		v9fs_uncache_page(inode, page);
}