1 /*
2  * V9FS cache definitions.
3  *
4  *  Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License version 2
8  *  as published by the Free Software Foundation.
9  *
10  *  This program is distributed in the hope that it will be useful,
11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  *  GNU General Public License for more details.
14  *
15  *  You should have received a copy of the GNU General Public License
16  *  along with this program; if not, write to:
17  *  Free Software Foundation
18  *  51 Franklin Street, Fifth Floor
19  *  Boston, MA  02111-1301  USA
20  *
21  */
22 
23 #include <linux/jiffies.h>
24 #include <linux/file.h>
25 #include <linux/slab.h>
26 #include <linux/stat.h>
27 #include <linux/sched.h>
28 #include <linux/fs.h>
29 #include <net/9p/9p.h>
30 
31 #include "v9fs.h"
32 #include "cache.h"
33 
34 #define CACHETAG_LEN  11
35 
36 struct fscache_netfs v9fs_cache_netfs = {
37 	.name 		= "9p",
38 	.version 	= 0,
39 };
40 
41 /**
42  * v9fs_random_cachetag - Generate a random tag to be associated
43  *			  with a new cache session.
44  *
45  * The value of jiffies is used for a fairly randomly cache tag.
46  */
47 
48 static
v9fs_random_cachetag(struct v9fs_session_info * v9ses)49 int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
50 {
51 	v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
52 	if (!v9ses->cachetag)
53 		return -ENOMEM;
54 
55 	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
56 }
57 
v9fs_cache_session_get_key(const void * cookie_netfs_data,void * buffer,uint16_t bufmax)58 static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
59 					   void *buffer, uint16_t bufmax)
60 {
61 	struct v9fs_session_info *v9ses;
62 	uint16_t klen = 0;
63 
64 	v9ses = (struct v9fs_session_info *)cookie_netfs_data;
65 	p9_debug(P9_DEBUG_FSC, "session %p buf %p size %u\n",
66 		 v9ses, buffer, bufmax);
67 
68 	if (v9ses->cachetag)
69 		klen = strlen(v9ses->cachetag);
70 
71 	if (klen > bufmax)
72 		return 0;
73 
74 	memcpy(buffer, v9ses->cachetag, klen);
75 	p9_debug(P9_DEBUG_FSC, "cache session tag %s\n", v9ses->cachetag);
76 	return klen;
77 }
78 
79 const struct fscache_cookie_def v9fs_cache_session_index_def = {
80 	.name		= "9P.session",
81 	.type		= FSCACHE_COOKIE_TYPE_INDEX,
82 	.get_key	= v9fs_cache_session_get_key,
83 };
84 
v9fs_cache_session_get_cookie(struct v9fs_session_info * v9ses)85 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
86 {
87 	/* If no cache session tag was specified, we generate a random one. */
88 	if (!v9ses->cachetag)
89 		v9fs_random_cachetag(v9ses);
90 
91 	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
92 						&v9fs_cache_session_index_def,
93 						v9ses);
94 	p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
95 		 v9ses, v9ses->fscache);
96 }
97 
v9fs_cache_session_put_cookie(struct v9fs_session_info * v9ses)98 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
99 {
100 	p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
101 		 v9ses, v9ses->fscache);
102 	fscache_relinquish_cookie(v9ses->fscache, 0);
103 	v9ses->fscache = NULL;
104 }
105 
106 
v9fs_cache_inode_get_key(const void * cookie_netfs_data,void * buffer,uint16_t bufmax)107 static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
108 					 void *buffer, uint16_t bufmax)
109 {
110 	const struct v9fs_inode *v9inode = cookie_netfs_data;
111 	memcpy(buffer, &v9inode->qid.path, sizeof(v9inode->qid.path));
112 	p9_debug(P9_DEBUG_FSC, "inode %p get key %llu\n",
113 		 &v9inode->vfs_inode, v9inode->qid.path);
114 	return sizeof(v9inode->qid.path);
115 }
116 
v9fs_cache_inode_get_attr(const void * cookie_netfs_data,uint64_t * size)117 static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
118 				      uint64_t *size)
119 {
120 	const struct v9fs_inode *v9inode = cookie_netfs_data;
121 	*size = i_size_read(&v9inode->vfs_inode);
122 
123 	p9_debug(P9_DEBUG_FSC, "inode %p get attr %llu\n",
124 		 &v9inode->vfs_inode, *size);
125 }
126 
v9fs_cache_inode_get_aux(const void * cookie_netfs_data,void * buffer,uint16_t buflen)127 static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
128 					 void *buffer, uint16_t buflen)
129 {
130 	const struct v9fs_inode *v9inode = cookie_netfs_data;
131 	memcpy(buffer, &v9inode->qid.version, sizeof(v9inode->qid.version));
132 	p9_debug(P9_DEBUG_FSC, "inode %p get aux %u\n",
133 		 &v9inode->vfs_inode, v9inode->qid.version);
134 	return sizeof(v9inode->qid.version);
135 }
136 
137 static enum
v9fs_cache_inode_check_aux(void * cookie_netfs_data,const void * buffer,uint16_t buflen)138 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
139 					    const void *buffer,
140 					    uint16_t buflen)
141 {
142 	const struct v9fs_inode *v9inode = cookie_netfs_data;
143 
144 	if (buflen != sizeof(v9inode->qid.version))
145 		return FSCACHE_CHECKAUX_OBSOLETE;
146 
147 	if (memcmp(buffer, &v9inode->qid.version,
148 		   sizeof(v9inode->qid.version)))
149 		return FSCACHE_CHECKAUX_OBSOLETE;
150 
151 	return FSCACHE_CHECKAUX_OKAY;
152 }
153 
v9fs_cache_inode_now_uncached(void * cookie_netfs_data)154 static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
155 {
156 	struct v9fs_inode *v9inode = cookie_netfs_data;
157 	struct pagevec pvec;
158 	pgoff_t first;
159 	int loop, nr_pages;
160 
161 	pagevec_init(&pvec, 0);
162 	first = 0;
163 
164 	for (;;) {
165 		nr_pages = pagevec_lookup(&pvec, v9inode->vfs_inode.i_mapping,
166 					  first,
167 					  PAGEVEC_SIZE - pagevec_count(&pvec));
168 		if (!nr_pages)
169 			break;
170 
171 		for (loop = 0; loop < nr_pages; loop++)
172 			ClearPageFsCache(pvec.pages[loop]);
173 
174 		first = pvec.pages[nr_pages - 1]->index + 1;
175 
176 		pvec.nr = nr_pages;
177 		pagevec_release(&pvec);
178 		cond_resched();
179 	}
180 }
181 
182 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
183 	.name		= "9p.inode",
184 	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
185 	.get_key	= v9fs_cache_inode_get_key,
186 	.get_attr	= v9fs_cache_inode_get_attr,
187 	.get_aux	= v9fs_cache_inode_get_aux,
188 	.check_aux	= v9fs_cache_inode_check_aux,
189 	.now_uncached	= v9fs_cache_inode_now_uncached,
190 };
191 
v9fs_cache_inode_get_cookie(struct inode * inode)192 void v9fs_cache_inode_get_cookie(struct inode *inode)
193 {
194 	struct v9fs_inode *v9inode;
195 	struct v9fs_session_info *v9ses;
196 
197 	if (!S_ISREG(inode->i_mode))
198 		return;
199 
200 	v9inode = V9FS_I(inode);
201 	if (v9inode->fscache)
202 		return;
203 
204 	v9ses = v9fs_inode2v9ses(inode);
205 	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
206 						  &v9fs_cache_inode_index_def,
207 						  v9inode);
208 
209 	p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
210 		 inode, v9inode->fscache);
211 }
212 
v9fs_cache_inode_put_cookie(struct inode * inode)213 void v9fs_cache_inode_put_cookie(struct inode *inode)
214 {
215 	struct v9fs_inode *v9inode = V9FS_I(inode);
216 
217 	if (!v9inode->fscache)
218 		return;
219 	p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
220 		 inode, v9inode->fscache);
221 
222 	fscache_relinquish_cookie(v9inode->fscache, 0);
223 	v9inode->fscache = NULL;
224 }
225 
v9fs_cache_inode_flush_cookie(struct inode * inode)226 void v9fs_cache_inode_flush_cookie(struct inode *inode)
227 {
228 	struct v9fs_inode *v9inode = V9FS_I(inode);
229 
230 	if (!v9inode->fscache)
231 		return;
232 	p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
233 		 inode, v9inode->fscache);
234 
235 	fscache_relinquish_cookie(v9inode->fscache, 1);
236 	v9inode->fscache = NULL;
237 }
238 
v9fs_cache_inode_set_cookie(struct inode * inode,struct file * filp)239 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
240 {
241 	struct v9fs_inode *v9inode = V9FS_I(inode);
242 	struct p9_fid *fid;
243 
244 	if (!v9inode->fscache)
245 		return;
246 
247 	spin_lock(&v9inode->fscache_lock);
248 	fid = filp->private_data;
249 	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
250 		v9fs_cache_inode_flush_cookie(inode);
251 	else
252 		v9fs_cache_inode_get_cookie(inode);
253 
254 	spin_unlock(&v9inode->fscache_lock);
255 }
256 
v9fs_cache_inode_reset_cookie(struct inode * inode)257 void v9fs_cache_inode_reset_cookie(struct inode *inode)
258 {
259 	struct v9fs_inode *v9inode = V9FS_I(inode);
260 	struct v9fs_session_info *v9ses;
261 	struct fscache_cookie *old;
262 
263 	if (!v9inode->fscache)
264 		return;
265 
266 	old = v9inode->fscache;
267 
268 	spin_lock(&v9inode->fscache_lock);
269 	fscache_relinquish_cookie(v9inode->fscache, 1);
270 
271 	v9ses = v9fs_inode2v9ses(inode);
272 	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
273 						  &v9fs_cache_inode_index_def,
274 						  v9inode);
275 	p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
276 		 inode, old, v9inode->fscache);
277 
278 	spin_unlock(&v9inode->fscache_lock);
279 }
280 
__v9fs_fscache_release_page(struct page * page,gfp_t gfp)281 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
282 {
283 	struct inode *inode = page->mapping->host;
284 	struct v9fs_inode *v9inode = V9FS_I(inode);
285 
286 	BUG_ON(!v9inode->fscache);
287 
288 	return fscache_maybe_release_page(v9inode->fscache, page, gfp);
289 }
290 
__v9fs_fscache_invalidate_page(struct page * page)291 void __v9fs_fscache_invalidate_page(struct page *page)
292 {
293 	struct inode *inode = page->mapping->host;
294 	struct v9fs_inode *v9inode = V9FS_I(inode);
295 
296 	BUG_ON(!v9inode->fscache);
297 
298 	if (PageFsCache(page)) {
299 		fscache_wait_on_page_write(v9inode->fscache, page);
300 		BUG_ON(!PageLocked(page));
301 		fscache_uncache_page(v9inode->fscache, page);
302 	}
303 }
304 
v9fs_vfs_readpage_complete(struct page * page,void * data,int error)305 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
306 				       int error)
307 {
308 	if (!error)
309 		SetPageUptodate(page);
310 
311 	unlock_page(page);
312 }
313 
314 /**
315  * __v9fs_readpage_from_fscache - read a page from cache
316  *
317  * Returns 0 if the pages are in cache and a BIO is submitted,
318  * 1 if the pages are not in cache and -error otherwise.
319  */
320 
__v9fs_readpage_from_fscache(struct inode * inode,struct page * page)321 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
322 {
323 	int ret;
324 	const struct v9fs_inode *v9inode = V9FS_I(inode);
325 
326 	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
327 	if (!v9inode->fscache)
328 		return -ENOBUFS;
329 
330 	ret = fscache_read_or_alloc_page(v9inode->fscache,
331 					 page,
332 					 v9fs_vfs_readpage_complete,
333 					 NULL,
334 					 GFP_KERNEL);
335 	switch (ret) {
336 	case -ENOBUFS:
337 	case -ENODATA:
338 		p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
339 		return 1;
340 	case 0:
341 		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
342 		return ret;
343 	default:
344 		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
345 		return ret;
346 	}
347 }
348 
349 /**
350  * __v9fs_readpages_from_fscache - read multiple pages from cache
351  *
352  * Returns 0 if the pages are in cache and a BIO is submitted,
353  * 1 if the pages are not in cache and -error otherwise.
354  */
355 
__v9fs_readpages_from_fscache(struct inode * inode,struct address_space * mapping,struct list_head * pages,unsigned * nr_pages)356 int __v9fs_readpages_from_fscache(struct inode *inode,
357 				  struct address_space *mapping,
358 				  struct list_head *pages,
359 				  unsigned *nr_pages)
360 {
361 	int ret;
362 	const struct v9fs_inode *v9inode = V9FS_I(inode);
363 
364 	p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
365 	if (!v9inode->fscache)
366 		return -ENOBUFS;
367 
368 	ret = fscache_read_or_alloc_pages(v9inode->fscache,
369 					  mapping, pages, nr_pages,
370 					  v9fs_vfs_readpage_complete,
371 					  NULL,
372 					  mapping_gfp_mask(mapping));
373 	switch (ret) {
374 	case -ENOBUFS:
375 	case -ENODATA:
376 		p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
377 		return 1;
378 	case 0:
379 		BUG_ON(!list_empty(pages));
380 		BUG_ON(*nr_pages != 0);
381 		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
382 		return ret;
383 	default:
384 		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
385 		return ret;
386 	}
387 }
388 
389 /**
390  * __v9fs_readpage_to_fscache - write a page to the cache
391  *
392  */
393 
__v9fs_readpage_to_fscache(struct inode * inode,struct page * page)394 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
395 {
396 	int ret;
397 	const struct v9fs_inode *v9inode = V9FS_I(inode);
398 
399 	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
400 	ret = fscache_write_page(v9inode->fscache, page, GFP_KERNEL);
401 	p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
402 	if (ret != 0)
403 		v9fs_uncache_page(inode, page);
404 }
405 
406 /*
407  * wait for a page to complete writing to the cache
408  */
__v9fs_fscache_wait_on_page_write(struct inode * inode,struct page * page)409 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
410 {
411 	const struct v9fs_inode *v9inode = V9FS_I(inode);
412 	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
413 	if (PageFsCache(page))
414 		fscache_wait_on_page_write(v9inode->fscache, page);
415 }
416