1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * stackglue.h
5  *
6  * Glue to the underlying cluster stack.
7  *
8  * Copyright (C) 2007 Oracle.  All rights reserved.
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public
12  * License as published by the Free Software Foundation, version 2.
13  *
14  * This program is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  * General Public License for more details.
18  */
19 
20 
21 #ifndef STACKGLUE_H
22 #define STACKGLUE_H
23 
24 #include <linux/types.h>
25 #include <linux/list.h>
26 #include <linux/dlmconstants.h>
27 
28 #include "dlm/dlmapi.h"
29 #include <linux/dlm.h>
30 
31 /* Needed for plock-related prototypes */
32 struct file;
33 struct file_lock;
34 
35 /*
36  * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
37  * some day, but right now we need it.  Let's fake it.  This value is larger
38  * than any flag in dlmconstants.h.
39  */
40 #define DLM_LKF_LOCAL		0x00100000
41 
42 /*
43  * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
44  * wants to be in a public header.
45  */
46 #define GROUP_NAME_MAX		64
47 
48 /* This shadows  OCFS2_CLUSTER_NAME_LEN */
49 #define CLUSTER_NAME_MAX	16
50 
51 
52 /*
53  * ocfs2_protocol_version changes when ocfs2 does something different in
54  * its inter-node behavior.  See dlmglue.c for more information.
55  */
56 struct ocfs2_protocol_version {
57 	u8 pv_major;
58 	u8 pv_minor;
59 };
60 
61 /*
62  * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
63  * has a pointer to separately allocated lvb space.  This struct exists only to
64  * include in the lksb union to make space for a combined dlm_lksb and lvb.
65  */
66 struct fsdlm_lksb_plus_lvb {
67 	struct dlm_lksb lksb;
68 	char lvb[DLM_LVB_LEN];
69 };
70 
71 /*
72  * A union of all lock status structures.  We define it here so that the
73  * size of the union is known.  Lock status structures are embedded in
74  * ocfs2 inodes.
75  */
76 struct ocfs2_cluster_connection;
77 struct ocfs2_dlm_lksb {
78 	 union {
79 		 struct dlm_lockstatus lksb_o2dlm;
80 		 struct dlm_lksb lksb_fsdlm;
81 		 struct fsdlm_lksb_plus_lvb padding;
82 	 };
83 	 struct ocfs2_cluster_connection *lksb_conn;
84 };
85 
86 /*
87  * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
88  */
89 struct ocfs2_locking_protocol {
90 	struct ocfs2_protocol_version lp_max_version;
91 	void (*lp_lock_ast)(struct ocfs2_dlm_lksb *lksb);
92 	void (*lp_blocking_ast)(struct ocfs2_dlm_lksb *lksb, int level);
93 	void (*lp_unlock_ast)(struct ocfs2_dlm_lksb *lksb, int error);
94 };
95 
96 
97 /*
98  * A cluster connection.  Mostly opaque to ocfs2, the connection holds
99  * state for the underlying stack.  ocfs2 does use cc_version to determine
100  * locking compatibility.
101  */
102 struct ocfs2_cluster_connection {
103 	char cc_name[GROUP_NAME_MAX + 1];
104 	int cc_namelen;
105 	char cc_cluster_name[CLUSTER_NAME_MAX + 1];
106 	int cc_cluster_name_len;
107 	struct ocfs2_protocol_version cc_version;
108 	struct ocfs2_locking_protocol *cc_proto;
109 	void (*cc_recovery_handler)(int node_num, void *recovery_data);
110 	void *cc_recovery_data;
111 	void *cc_lockspace;
112 	void *cc_private;
113 };
114 
115 /*
116  * Each cluster stack implements the stack operations structure.  Not used
117  * in the ocfs2 code, the stackglue code translates generic cluster calls
118  * into stack operations.
119  */
120 struct ocfs2_stack_operations {
121 	/*
122 	 * The fs code calls ocfs2_cluster_connect() to attach a new
123 	 * filesystem to the cluster stack.  The ->connect() op is passed
124 	 * an ocfs2_cluster_connection with the name and recovery field
125 	 * filled in.
126 	 *
127 	 * The stack must set up any notification mechanisms and create
128 	 * the filesystem lockspace in the DLM.  The lockspace should be
129 	 * stored on cc_lockspace.  Any other information can be stored on
130 	 * cc_private.
131 	 *
132 	 * ->connect() must not return until it is guaranteed that
133 	 *
134 	 *  - Node down notifications for the filesystem will be received
135 	 *    and passed to conn->cc_recovery_handler().
136 	 *  - Locking requests for the filesystem will be processed.
137 	 */
138 	int (*connect)(struct ocfs2_cluster_connection *conn);
139 
140 	/*
141 	 * The fs code calls ocfs2_cluster_disconnect() when a filesystem
142 	 * no longer needs cluster services.  All DLM locks have been
143 	 * dropped, and recovery notification is being ignored by the
144 	 * fs code.  The stack must disengage from the DLM and discontinue
145 	 * recovery notification.
146 	 *
147 	 * Once ->disconnect() has returned, the connection structure will
148 	 * be freed.  Thus, a stack must not return from ->disconnect()
149 	 * until it will no longer reference the conn pointer.
150 	 *
151 	 * Once this call returns, the stack glue will be dropping this
152 	 * connection's reference on the module.
153 	 */
154 	int (*disconnect)(struct ocfs2_cluster_connection *conn);
155 
156 	/*
157 	 * ->this_node() returns the cluster's unique identifier for the
158 	 * local node.
159 	 */
160 	int (*this_node)(struct ocfs2_cluster_connection *conn,
161 			 unsigned int *node);
162 
163 	/*
164 	 * Call the underlying dlm lock function.  The ->dlm_lock()
165 	 * callback should convert the flags and mode as appropriate.
166 	 *
167 	 * ast and bast functions are not part of the call because the
168 	 * stack will likely want to wrap ast and bast calls before passing
169 	 * them to stack->sp_proto.  There is no astarg.  The lksb will
170 	 * be passed back to the ast and bast functions.  The caller can
171 	 * use this to find their object.
172 	 */
173 	int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
174 			int mode,
175 			struct ocfs2_dlm_lksb *lksb,
176 			u32 flags,
177 			void *name,
178 			unsigned int namelen);
179 
180 	/*
181 	 * Call the underlying dlm unlock function.  The ->dlm_unlock()
182 	 * function should convert the flags as appropriate.
183 	 *
184 	 * The unlock ast is not passed, as the stack will want to wrap
185 	 * it before calling stack->sp_proto->lp_unlock_ast().  There is
186 	 * no astarg.  The lksb will be passed back to the unlock ast
187 	 * function.  The caller can use this to find their object.
188 	 */
189 	int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
190 			  struct ocfs2_dlm_lksb *lksb,
191 			  u32 flags);
192 
193 	/*
194 	 * Return the status of the current lock status block.  The fs
195 	 * code should never dereference the union.  The ->lock_status()
196 	 * callback pulls out the stack-specific lksb, converts the status
197 	 * to a proper errno, and returns it.
198 	 */
199 	int (*lock_status)(struct ocfs2_dlm_lksb *lksb);
200 
201 	/*
202 	 * Return non-zero if the LVB is valid.
203 	 */
204 	int (*lvb_valid)(struct ocfs2_dlm_lksb *lksb);
205 
206 	/*
207 	 * Pull the lvb pointer off of the stack-specific lksb.
208 	 */
209 	void *(*lock_lvb)(struct ocfs2_dlm_lksb *lksb);
210 
211 	/*
212 	 * Cluster-aware posix locks
213 	 *
214 	 * This is NULL for stacks which do not support posix locks.
215 	 */
216 	int (*plock)(struct ocfs2_cluster_connection *conn,
217 		     u64 ino,
218 		     struct file *file,
219 		     int cmd,
220 		     struct file_lock *fl);
221 
222 	/*
223 	 * This is an optoinal debugging hook.  If provided, the
224 	 * stack can dump debugging information about this lock.
225 	 */
226 	void (*dump_lksb)(struct ocfs2_dlm_lksb *lksb);
227 };
228 
229 /*
230  * Each stack plugin must describe itself by registering a
231  * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
232  * stack driver.
233  */
234 struct ocfs2_stack_plugin {
235 	char *sp_name;
236 	struct ocfs2_stack_operations *sp_ops;
237 	struct module *sp_owner;
238 
239 	/* These are managed by the stackglue code. */
240 	struct list_head sp_list;
241 	unsigned int sp_count;
242 	struct ocfs2_protocol_version sp_max_proto;
243 };
244 
245 
246 /* Used by the filesystem */
247 int ocfs2_cluster_connect(const char *stack_name,
248 			  const char *cluster_name,
249 			  int cluster_name_len,
250 			  const char *group,
251 			  int grouplen,
252 			  struct ocfs2_locking_protocol *lproto,
253 			  void (*recovery_handler)(int node_num,
254 						   void *recovery_data),
255 			  void *recovery_data,
256 			  struct ocfs2_cluster_connection **conn);
257 /*
258  * Used by callers that don't store their stack name.  They must ensure
259  * all nodes have the same stack.
260  */
261 int ocfs2_cluster_connect_agnostic(const char *group,
262 				   int grouplen,
263 				   struct ocfs2_locking_protocol *lproto,
264 				   void (*recovery_handler)(int node_num,
265 							    void *recovery_data),
266 				   void *recovery_data,
267 				   struct ocfs2_cluster_connection **conn);
268 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
269 			     int hangup_pending);
270 void ocfs2_cluster_hangup(const char *group, int grouplen);
271 int ocfs2_cluster_this_node(struct ocfs2_cluster_connection *conn,
272 			    unsigned int *node);
273 
274 struct ocfs2_lock_res;
275 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
276 		   int mode,
277 		   struct ocfs2_dlm_lksb *lksb,
278 		   u32 flags,
279 		   void *name,
280 		   unsigned int namelen);
281 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
282 		     struct ocfs2_dlm_lksb *lksb,
283 		     u32 flags);
284 
285 int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb);
286 int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb);
287 void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb);
288 void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb);
289 
290 int ocfs2_stack_supports_plocks(void);
291 int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
292 		struct file *file, int cmd, struct file_lock *fl);
293 
294 void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_proto);
295 
296 
297 /* Used by stack plugins */
298 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
299 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
300 
301 extern struct kset *ocfs2_kset;
302 
303 #endif  /* STACKGLUE_H */
304