xref: /openbmc/linux/fs/lockd/svcsubs.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * linux/fs/lockd/svcsubs.c
3  *
4  * Various support routines for the NLM server.
5  *
6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
7  */
8 
9 #include <linux/types.h>
10 #include <linux/string.h>
11 #include <linux/time.h>
12 #include <linux/in.h>
13 #include <linux/mutex.h>
14 #include <linux/sunrpc/svc.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/nfsd/nfsfh.h>
17 #include <linux/nfsd/export.h>
18 #include <linux/lockd/lockd.h>
19 #include <linux/lockd/share.h>
20 #include <linux/lockd/sm_inter.h>
21 
22 #define NLMDBG_FACILITY		NLMDBG_SVCSUBS
23 
24 
25 /*
26  * Global file hash table
27  */
28 #define FILE_HASH_BITS		7
29 #define FILE_NRHASH		(1<<FILE_HASH_BITS)
30 static struct hlist_head	nlm_files[FILE_NRHASH];
31 static DEFINE_MUTEX(nlm_file_mutex);
32 
33 #ifdef NFSD_DEBUG
34 static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
35 {
36 	u32 *fhp = (u32*)f->data;
37 
38 	/* print the first 32 bytes of the fh */
39 	dprintk("lockd: %s (%08x %08x %08x %08x %08x %08x %08x %08x)\n",
40 		msg, fhp[0], fhp[1], fhp[2], fhp[3],
41 		fhp[4], fhp[5], fhp[6], fhp[7]);
42 }
43 
44 static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
45 {
46 	struct inode *inode = file->f_file->f_path.dentry->d_inode;
47 
48 	dprintk("lockd: %s %s/%ld\n",
49 		msg, inode->i_sb->s_id, inode->i_ino);
50 }
51 #else
52 static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
53 {
54 	return;
55 }
56 
57 static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
58 {
59 	return;
60 }
61 #endif
62 
63 static inline unsigned int file_hash(struct nfs_fh *f)
64 {
65 	unsigned int tmp=0;
66 	int i;
67 	for (i=0; i<NFS2_FHSIZE;i++)
68 		tmp += f->data[i];
69 	return tmp & (FILE_NRHASH - 1);
70 }
71 
72 /*
73  * Lookup file info. If it doesn't exist, create a file info struct
74  * and open a (VFS) file for the given inode.
75  *
76  * FIXME:
77  * Note that we open the file O_RDONLY even when creating write locks.
78  * This is not quite right, but for now, we assume the client performs
79  * the proper R/W checking.
80  */
81 __be32
82 nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
83 					struct nfs_fh *f)
84 {
85 	struct hlist_node *pos;
86 	struct nlm_file	*file;
87 	unsigned int	hash;
88 	__be32		nfserr;
89 
90 	nlm_debug_print_fh("nlm_file_lookup", f);
91 
92 	hash = file_hash(f);
93 
94 	/* Lock file table */
95 	mutex_lock(&nlm_file_mutex);
96 
97 	hlist_for_each_entry(file, pos, &nlm_files[hash], f_list)
98 		if (!nfs_compare_fh(&file->f_handle, f))
99 			goto found;
100 
101 	nlm_debug_print_fh("creating file for", f);
102 
103 	nfserr = nlm_lck_denied_nolocks;
104 	file = kzalloc(sizeof(*file), GFP_KERNEL);
105 	if (!file)
106 		goto out_unlock;
107 
108 	memcpy(&file->f_handle, f, sizeof(struct nfs_fh));
109 	mutex_init(&file->f_mutex);
110 	INIT_HLIST_NODE(&file->f_list);
111 	INIT_LIST_HEAD(&file->f_blocks);
112 
113 	/* Open the file. Note that this must not sleep for too long, else
114 	 * we would lock up lockd:-) So no NFS re-exports, folks.
115 	 *
116 	 * We have to make sure we have the right credential to open
117 	 * the file.
118 	 */
119 	if ((nfserr = nlmsvc_ops->fopen(rqstp, f, &file->f_file)) != 0) {
120 		dprintk("lockd: open failed (error %d)\n", nfserr);
121 		goto out_free;
122 	}
123 
124 	hlist_add_head(&file->f_list, &nlm_files[hash]);
125 
126 found:
127 	dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
128 	*result = file;
129 	file->f_count++;
130 	nfserr = 0;
131 
132 out_unlock:
133 	mutex_unlock(&nlm_file_mutex);
134 	return nfserr;
135 
136 out_free:
137 	kfree(file);
138 	goto out_unlock;
139 }
140 
141 /*
142  * Delete a file after having released all locks, blocks and shares
143  */
144 static inline void
145 nlm_delete_file(struct nlm_file *file)
146 {
147 	nlm_debug_print_file("closing file", file);
148 	if (!hlist_unhashed(&file->f_list)) {
149 		hlist_del(&file->f_list);
150 		nlmsvc_ops->fclose(file->f_file);
151 		kfree(file);
152 	} else {
153 		printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
154 	}
155 }
156 
157 /*
158  * Loop over all locks on the given file and perform the specified
159  * action.
160  */
161 static int
162 nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
163 			nlm_host_match_fn_t match)
164 {
165 	struct inode	 *inode = nlmsvc_file_inode(file);
166 	struct file_lock *fl;
167 	struct nlm_host	 *lockhost;
168 
169 again:
170 	file->f_locks = 0;
171 	for (fl = inode->i_flock; fl; fl = fl->fl_next) {
172 		if (fl->fl_lmops != &nlmsvc_lock_operations)
173 			continue;
174 
175 		/* update current lock count */
176 		file->f_locks++;
177 
178 		lockhost = (struct nlm_host *) fl->fl_owner;
179 		if (match(lockhost, host)) {
180 			struct file_lock lock = *fl;
181 
182 			lock.fl_type  = F_UNLCK;
183 			lock.fl_start = 0;
184 			lock.fl_end   = OFFSET_MAX;
185 			if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
186 				printk("lockd: unlock failure in %s:%d\n",
187 						__FILE__, __LINE__);
188 				return 1;
189 			}
190 			goto again;
191 		}
192 	}
193 
194 	return 0;
195 }
196 
197 /*
198  * Inspect a single file
199  */
200 static inline int
201 nlm_inspect_file(struct nlm_host *host, struct nlm_file *file, nlm_host_match_fn_t match)
202 {
203 	nlmsvc_traverse_blocks(host, file, match);
204 	nlmsvc_traverse_shares(host, file, match);
205 	return nlm_traverse_locks(host, file, match);
206 }
207 
208 /*
209  * Quick check whether there are still any locks, blocks or
210  * shares on a given file.
211  */
212 static inline int
213 nlm_file_inuse(struct nlm_file *file)
214 {
215 	struct inode	 *inode = nlmsvc_file_inode(file);
216 	struct file_lock *fl;
217 
218 	if (file->f_count || !list_empty(&file->f_blocks) || file->f_shares)
219 		return 1;
220 
221 	for (fl = inode->i_flock; fl; fl = fl->fl_next) {
222 		if (fl->fl_lmops == &nlmsvc_lock_operations)
223 			return 1;
224 	}
225 	file->f_locks = 0;
226 	return 0;
227 }
228 
229 /*
230  * Loop over all files in the file table.
231  */
232 static int
233 nlm_traverse_files(struct nlm_host *host, nlm_host_match_fn_t match)
234 {
235 	struct hlist_node *pos, *next;
236 	struct nlm_file	*file;
237 	int i, ret = 0;
238 
239 	mutex_lock(&nlm_file_mutex);
240 	for (i = 0; i < FILE_NRHASH; i++) {
241 		hlist_for_each_entry_safe(file, pos, next, &nlm_files[i], f_list) {
242 			file->f_count++;
243 			mutex_unlock(&nlm_file_mutex);
244 
245 			/* Traverse locks, blocks and shares of this file
246 			 * and update file->f_locks count */
247 			if (nlm_inspect_file(host, file, match))
248 				ret = 1;
249 
250 			mutex_lock(&nlm_file_mutex);
251 			file->f_count--;
252 			/* No more references to this file. Let go of it. */
253 			if (list_empty(&file->f_blocks) && !file->f_locks
254 			 && !file->f_shares && !file->f_count) {
255 				hlist_del(&file->f_list);
256 				nlmsvc_ops->fclose(file->f_file);
257 				kfree(file);
258 			}
259 		}
260 	}
261 	mutex_unlock(&nlm_file_mutex);
262 	return ret;
263 }
264 
265 /*
266  * Release file. If there are no more remote locks on this file,
267  * close it and free the handle.
268  *
269  * Note that we can't do proper reference counting without major
270  * contortions because the code in fs/locks.c creates, deletes and
271  * splits locks without notification. Our only way is to walk the
272  * entire lock list each time we remove a lock.
273  */
274 void
275 nlm_release_file(struct nlm_file *file)
276 {
277 	dprintk("lockd: nlm_release_file(%p, ct = %d)\n",
278 				file, file->f_count);
279 
280 	/* Lock file table */
281 	mutex_lock(&nlm_file_mutex);
282 
283 	/* If there are no more locks etc, delete the file */
284 	if (--file->f_count == 0 && !nlm_file_inuse(file))
285 		nlm_delete_file(file);
286 
287 	mutex_unlock(&nlm_file_mutex);
288 }
289 
290 /*
291  * Helpers function for resource traversal
292  *
293  * nlmsvc_mark_host:
294  *	used by the garbage collector; simply sets h_inuse.
295  *	Always returns 0.
296  *
297  * nlmsvc_same_host:
298  *	returns 1 iff the two hosts match. Used to release
299  *	all resources bound to a specific host.
300  *
301  * nlmsvc_is_client:
302  *	returns 1 iff the host is a client.
303  *	Used by nlmsvc_invalidate_all
304  */
305 static int
306 nlmsvc_mark_host(struct nlm_host *host, struct nlm_host *dummy)
307 {
308 	host->h_inuse = 1;
309 	return 0;
310 }
311 
312 static int
313 nlmsvc_same_host(struct nlm_host *host, struct nlm_host *other)
314 {
315 	return host == other;
316 }
317 
318 static int
319 nlmsvc_is_client(struct nlm_host *host, struct nlm_host *dummy)
320 {
321 	if (host->h_server) {
322 		/* we are destroying locks even though the client
323 		 * hasn't asked us too, so don't unmonitor the
324 		 * client
325 		 */
326 		if (host->h_nsmhandle)
327 			host->h_nsmhandle->sm_sticky = 1;
328 		return 1;
329 	} else
330 		return 0;
331 }
332 
333 /*
334  * Mark all hosts that still hold resources
335  */
336 void
337 nlmsvc_mark_resources(void)
338 {
339 	dprintk("lockd: nlmsvc_mark_resources\n");
340 	nlm_traverse_files(NULL, nlmsvc_mark_host);
341 }
342 
343 /*
344  * Release all resources held by the given client
345  */
346 void
347 nlmsvc_free_host_resources(struct nlm_host *host)
348 {
349 	dprintk("lockd: nlmsvc_free_host_resources\n");
350 
351 	if (nlm_traverse_files(host, nlmsvc_same_host)) {
352 		printk(KERN_WARNING
353 			"lockd: couldn't remove all locks held by %s\n",
354 			host->h_name);
355 		BUG();
356 	}
357 }
358 
359 /*
360  * Remove all locks held for clients
361  */
362 void
363 nlmsvc_invalidate_all(void)
364 {
365 	/* Release all locks held by NFS clients.
366 	 * Previously, the code would call
367 	 * nlmsvc_free_host_resources for each client in
368 	 * turn, which is about as inefficient as it gets.
369 	 * Now we just do it once in nlm_traverse_files.
370 	 */
371 	nlm_traverse_files(NULL, nlmsvc_is_client);
372 }
373