xref: /openbmc/linux/fs/ceph/locks.c (revision b34e08d5)
1 #include <linux/ceph/ceph_debug.h>
2 
3 #include <linux/file.h>
4 #include <linux/namei.h>
5 #include <linux/random.h>
6 
7 #include "super.h"
8 #include "mds_client.h"
9 #include <linux/ceph/pagelist.h>
10 
11 static u64 lock_secret;
12 
13 static inline u64 secure_addr(void *addr)
14 {
15 	u64 v = lock_secret ^ (u64)(unsigned long)addr;
16 	/*
17 	 * Set the most significant bit, so that MDS knows the 'owner'
18 	 * is sufficient to identify the owner of lock. (old code uses
19 	 * both 'owner' and 'pid')
20 	 */
21 	v |= (1ULL << 63);
22 	return v;
23 }
24 
25 void __init ceph_flock_init(void)
26 {
27 	get_random_bytes(&lock_secret, sizeof(lock_secret));
28 }
29 
30 /**
31  * Implement fcntl and flock locking functions.
32  */
33 static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
34 			     int cmd, u8 wait, struct file_lock *fl)
35 {
36 	struct inode *inode = file_inode(file);
37 	struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
38 	struct ceph_mds_request *req;
39 	int err;
40 	u64 length = 0;
41 	u64 owner;
42 
43 	req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
44 	if (IS_ERR(req))
45 		return PTR_ERR(req);
46 	req->r_inode = inode;
47 	ihold(inode);
48 
49 	/* mds requires start and length rather than start and end */
50 	if (LLONG_MAX == fl->fl_end)
51 		length = 0;
52 	else
53 		length = fl->fl_end - fl->fl_start + 1;
54 
55 	if (lock_type == CEPH_LOCK_FCNTL)
56 		owner = secure_addr(fl->fl_owner);
57 	else
58 		owner = secure_addr(fl->fl_file);
59 
60 	dout("ceph_lock_message: rule: %d, op: %d, owner: %llx, pid: %llu, "
61 	     "start: %llu, length: %llu, wait: %d, type: %d", (int)lock_type,
62 	     (int)operation, owner, (u64)fl->fl_pid, fl->fl_start, length,
63 	     wait, fl->fl_type);
64 
65 	req->r_args.filelock_change.rule = lock_type;
66 	req->r_args.filelock_change.type = cmd;
67 	req->r_args.filelock_change.owner = cpu_to_le64(owner);
68 	req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
69 	req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
70 	req->r_args.filelock_change.length = cpu_to_le64(length);
71 	req->r_args.filelock_change.wait = wait;
72 
73 	err = ceph_mdsc_do_request(mdsc, inode, req);
74 
75 	if (operation == CEPH_MDS_OP_GETFILELOCK) {
76 		fl->fl_pid = le64_to_cpu(req->r_reply_info.filelock_reply->pid);
77 		if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
78 			fl->fl_type = F_RDLCK;
79 		else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
80 			fl->fl_type = F_WRLCK;
81 		else
82 			fl->fl_type = F_UNLCK;
83 
84 		fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
85 		length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
86 						 le64_to_cpu(req->r_reply_info.filelock_reply->length);
87 		if (length >= 1)
88 			fl->fl_end = length -1;
89 		else
90 			fl->fl_end = 0;
91 
92 	}
93 	ceph_mdsc_put_request(req);
94 	dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
95 	     "length: %llu, wait: %d, type: %d, err code %d", (int)lock_type,
96 	     (int)operation, (u64)fl->fl_pid, fl->fl_start,
97 	     length, wait, fl->fl_type, err);
98 	return err;
99 }
100 
101 /**
102  * Attempt to set an fcntl lock.
103  * For now, this just goes away to the server. Later it may be more awesome.
104  */
105 int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
106 {
107 	u8 lock_cmd;
108 	int err;
109 	u8 wait = 0;
110 	u16 op = CEPH_MDS_OP_SETFILELOCK;
111 
112 	if (!(fl->fl_flags & FL_POSIX))
113 		return -ENOLCK;
114 	/* No mandatory locks */
115 	if (__mandatory_lock(file->f_mapping->host) && fl->fl_type != F_UNLCK)
116 		return -ENOLCK;
117 
118 	dout("ceph_lock, fl_owner: %p", fl->fl_owner);
119 
120 	/* set wait bit as appropriate, then make command as Ceph expects it*/
121 	if (IS_GETLK(cmd))
122 		op = CEPH_MDS_OP_GETFILELOCK;
123 	else if (IS_SETLKW(cmd))
124 		wait = 1;
125 
126 	if (F_RDLCK == fl->fl_type)
127 		lock_cmd = CEPH_LOCK_SHARED;
128 	else if (F_WRLCK == fl->fl_type)
129 		lock_cmd = CEPH_LOCK_EXCL;
130 	else
131 		lock_cmd = CEPH_LOCK_UNLOCK;
132 
133 	err = ceph_lock_message(CEPH_LOCK_FCNTL, op, file, lock_cmd, wait, fl);
134 	if (!err) {
135 		if (op != CEPH_MDS_OP_GETFILELOCK) {
136 			dout("mds locked, locking locally");
137 			err = posix_lock_file(file, fl, NULL);
138 			if (err && (CEPH_MDS_OP_SETFILELOCK == op)) {
139 				/* undo! This should only happen if
140 				 * the kernel detects local
141 				 * deadlock. */
142 				ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
143 						  CEPH_LOCK_UNLOCK, 0, fl);
144 				dout("got %d on posix_lock_file, undid lock",
145 				     err);
146 			}
147 		}
148 
149 	} else if (err == -ERESTARTSYS) {
150 		dout("undoing lock\n");
151 		ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
152 				  CEPH_LOCK_UNLOCK, 0, fl);
153 	}
154 	return err;
155 }
156 
157 int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
158 {
159 	u8 lock_cmd;
160 	int err;
161 	u8 wait = 0;
162 
163 	if (!(fl->fl_flags & FL_FLOCK))
164 		return -ENOLCK;
165 	/* No mandatory locks */
166 	if (__mandatory_lock(file->f_mapping->host) && fl->fl_type != F_UNLCK)
167 		return -ENOLCK;
168 
169 	dout("ceph_flock, fl_file: %p", fl->fl_file);
170 
171 	if (IS_SETLKW(cmd))
172 		wait = 1;
173 
174 	if (F_RDLCK == fl->fl_type)
175 		lock_cmd = CEPH_LOCK_SHARED;
176 	else if (F_WRLCK == fl->fl_type)
177 		lock_cmd = CEPH_LOCK_EXCL;
178 	else
179 		lock_cmd = CEPH_LOCK_UNLOCK;
180 
181 	err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
182 				file, lock_cmd, wait, fl);
183 	if (!err) {
184 		err = flock_lock_file_wait(file, fl);
185 		if (err) {
186 			ceph_lock_message(CEPH_LOCK_FLOCK,
187 					  CEPH_MDS_OP_SETFILELOCK,
188 					  file, CEPH_LOCK_UNLOCK, 0, fl);
189 			dout("got %d on flock_lock_file_wait, undid lock", err);
190 		}
191 	} else if (err == -ERESTARTSYS) {
192 		dout("undoing lock\n");
193 		ceph_lock_message(CEPH_LOCK_FLOCK,
194 				  CEPH_MDS_OP_SETFILELOCK,
195 				  file, CEPH_LOCK_UNLOCK, 0, fl);
196 	}
197 	return err;
198 }
199 
200 /**
201  * Must be called with lock_flocks() already held. Fills in the passed
202  * counter variables, so you can prepare pagelist metadata before calling
203  * ceph_encode_locks.
204  */
205 void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
206 {
207 	struct file_lock *lock;
208 
209 	*fcntl_count = 0;
210 	*flock_count = 0;
211 
212 	for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
213 		if (lock->fl_flags & FL_POSIX)
214 			++(*fcntl_count);
215 		else if (lock->fl_flags & FL_FLOCK)
216 			++(*flock_count);
217 	}
218 	dout("counted %d flock locks and %d fcntl locks",
219 	     *flock_count, *fcntl_count);
220 }
221 
222 /**
223  * Encode the flock and fcntl locks for the given inode into the ceph_filelock
224  * array. Must be called with inode->i_lock already held.
225  * If we encounter more of a specific lock type than expected, return -ENOSPC.
226  */
227 int ceph_encode_locks_to_buffer(struct inode *inode,
228 				struct ceph_filelock *flocks,
229 				int num_fcntl_locks, int num_flock_locks)
230 {
231 	struct file_lock *lock;
232 	int err = 0;
233 	int seen_fcntl = 0;
234 	int seen_flock = 0;
235 	int l = 0;
236 
237 	dout("encoding %d flock and %d fcntl locks", num_flock_locks,
238 	     num_fcntl_locks);
239 
240 	for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
241 		if (lock->fl_flags & FL_POSIX) {
242 			++seen_fcntl;
243 			if (seen_fcntl > num_fcntl_locks) {
244 				err = -ENOSPC;
245 				goto fail;
246 			}
247 			err = lock_to_ceph_filelock(lock, &flocks[l]);
248 			if (err)
249 				goto fail;
250 			++l;
251 		}
252 	}
253 	for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
254 		if (lock->fl_flags & FL_FLOCK) {
255 			++seen_flock;
256 			if (seen_flock > num_flock_locks) {
257 				err = -ENOSPC;
258 				goto fail;
259 			}
260 			err = lock_to_ceph_filelock(lock, &flocks[l]);
261 			if (err)
262 				goto fail;
263 			++l;
264 		}
265 	}
266 fail:
267 	return err;
268 }
269 
270 /**
271  * Copy the encoded flock and fcntl locks into the pagelist.
272  * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
273  * sequential flock locks.
274  * Returns zero on success.
275  */
276 int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
277 			   struct ceph_pagelist *pagelist,
278 			   int num_fcntl_locks, int num_flock_locks)
279 {
280 	int err = 0;
281 	__le32 nlocks;
282 
283 	nlocks = cpu_to_le32(num_fcntl_locks);
284 	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
285 	if (err)
286 		goto out_fail;
287 
288 	err = ceph_pagelist_append(pagelist, flocks,
289 				   num_fcntl_locks * sizeof(*flocks));
290 	if (err)
291 		goto out_fail;
292 
293 	nlocks = cpu_to_le32(num_flock_locks);
294 	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
295 	if (err)
296 		goto out_fail;
297 
298 	err = ceph_pagelist_append(pagelist,
299 				   &flocks[num_fcntl_locks],
300 				   num_flock_locks * sizeof(*flocks));
301 out_fail:
302 	return err;
303 }
304 
305 /*
306  * Given a pointer to a lock, convert it to a ceph filelock
307  */
308 int lock_to_ceph_filelock(struct file_lock *lock,
309 			  struct ceph_filelock *cephlock)
310 {
311 	int err = 0;
312 	cephlock->start = cpu_to_le64(lock->fl_start);
313 	cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
314 	cephlock->client = cpu_to_le64(0);
315 	cephlock->pid = cpu_to_le64((u64)lock->fl_pid);
316 	if (lock->fl_flags & FL_POSIX)
317 		cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));
318 	else
319 		cephlock->owner = cpu_to_le64(secure_addr(lock->fl_file));
320 
321 	switch (lock->fl_type) {
322 	case F_RDLCK:
323 		cephlock->type = CEPH_LOCK_SHARED;
324 		break;
325 	case F_WRLCK:
326 		cephlock->type = CEPH_LOCK_EXCL;
327 		break;
328 	case F_UNLCK:
329 		cephlock->type = CEPH_LOCK_UNLOCK;
330 		break;
331 	default:
332 		dout("Have unknown lock type %d", lock->fl_type);
333 		err = -EINVAL;
334 	}
335 
336 	return err;
337 }
338