xref: /openbmc/linux/fs/ocfs2/stackglue.h (revision 22246614)
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 /*
32  * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
33  * some day, but right now we need it.  Let's fake it.  This value is larger
34  * than any flag in dlmconstants.h.
35  */
36 #define DLM_LKF_LOCAL		0x00100000
37 
38 /*
39  * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
40  * wants to be in a public header.
41  */
42 #define GROUP_NAME_MAX		64
43 
44 
45 /*
46  * ocfs2_protocol_version changes when ocfs2 does something different in
47  * its inter-node behavior.  See dlmglue.c for more information.
48  */
49 struct ocfs2_protocol_version {
50 	u8 pv_major;
51 	u8 pv_minor;
52 };
53 
54 /*
55  * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
56  */
57 struct ocfs2_locking_protocol {
58 	struct ocfs2_protocol_version lp_max_version;
59 	void (*lp_lock_ast)(void *astarg);
60 	void (*lp_blocking_ast)(void *astarg, int level);
61 	void (*lp_unlock_ast)(void *astarg, int error);
62 };
63 
64 
65 /*
66  * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
67  * has a pointer to separately allocated lvb space.  This struct exists only to
68  * include in the lksb union to make space for a combined dlm_lksb and lvb.
69  */
70 struct fsdlm_lksb_plus_lvb {
71 	struct dlm_lksb lksb;
72 	char lvb[DLM_LVB_LEN];
73 };
74 
75 /*
76  * A union of all lock status structures.  We define it here so that the
77  * size of the union is known.  Lock status structures are embedded in
78  * ocfs2 inodes.
79  */
80 union ocfs2_dlm_lksb {
81 	struct dlm_lockstatus lksb_o2dlm;
82 	struct dlm_lksb lksb_fsdlm;
83 	struct fsdlm_lksb_plus_lvb padding;
84 };
85 
86 /*
87  * A cluster connection.  Mostly opaque to ocfs2, the connection holds
88  * state for the underlying stack.  ocfs2 does use cc_version to determine
89  * locking compatibility.
90  */
91 struct ocfs2_cluster_connection {
92 	char cc_name[GROUP_NAME_MAX];
93 	int cc_namelen;
94 	struct ocfs2_protocol_version cc_version;
95 	void (*cc_recovery_handler)(int node_num, void *recovery_data);
96 	void *cc_recovery_data;
97 	void *cc_lockspace;
98 	void *cc_private;
99 };
100 
101 /*
102  * Each cluster stack implements the stack operations structure.  Not used
103  * in the ocfs2 code, the stackglue code translates generic cluster calls
104  * into stack operations.
105  */
106 struct ocfs2_stack_operations {
107 	/*
108 	 * The fs code calls ocfs2_cluster_connect() to attach a new
109 	 * filesystem to the cluster stack.  The ->connect() op is passed
110 	 * an ocfs2_cluster_connection with the name and recovery field
111 	 * filled in.
112 	 *
113 	 * The stack must set up any notification mechanisms and create
114 	 * the filesystem lockspace in the DLM.  The lockspace should be
115 	 * stored on cc_lockspace.  Any other information can be stored on
116 	 * cc_private.
117 	 *
118 	 * ->connect() must not return until it is guaranteed that
119 	 *
120 	 *  - Node down notifications for the filesystem will be recieved
121 	 *    and passed to conn->cc_recovery_handler().
122 	 *  - Locking requests for the filesystem will be processed.
123 	 */
124 	int (*connect)(struct ocfs2_cluster_connection *conn);
125 
126 	/*
127 	 * The fs code calls ocfs2_cluster_disconnect() when a filesystem
128 	 * no longer needs cluster services.  All DLM locks have been
129 	 * dropped, and recovery notification is being ignored by the
130 	 * fs code.  The stack must disengage from the DLM and discontinue
131 	 * recovery notification.
132 	 *
133 	 * Once ->disconnect() has returned, the connection structure will
134 	 * be freed.  Thus, a stack must not return from ->disconnect()
135 	 * until it will no longer reference the conn pointer.
136 	 *
137 	 * If hangup_pending is zero, ocfs2_cluster_disconnect() will also
138 	 * be dropping the reference on the module.
139 	 */
140 	int (*disconnect)(struct ocfs2_cluster_connection *conn,
141 			  int hangup_pending);
142 
143 	/*
144 	 * ocfs2_cluster_hangup() exists for compatibility with older
145 	 * ocfs2 tools.  Only the classic stack really needs it.  As such
146 	 * ->hangup() is not required of all stacks.  See the comment by
147 	 * ocfs2_cluster_hangup() for more details.
148 	 *
149 	 * Note that ocfs2_cluster_hangup() can only be called if
150 	 * hangup_pending was passed to ocfs2_cluster_disconnect().
151 	 */
152 	void (*hangup)(const char *group, int grouplen);
153 
154 	/*
155 	 * ->this_node() returns the cluster's unique identifier for the
156 	 * local node.
157 	 */
158 	int (*this_node)(unsigned int *node);
159 
160 	/*
161 	 * Call the underlying dlm lock function.  The ->dlm_lock()
162 	 * callback should convert the flags and mode as appropriate.
163 	 *
164 	 * ast and bast functions are not part of the call because the
165 	 * stack will likely want to wrap ast and bast calls before passing
166 	 * them to stack->sp_proto.
167 	 */
168 	int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
169 			int mode,
170 			union ocfs2_dlm_lksb *lksb,
171 			u32 flags,
172 			void *name,
173 			unsigned int namelen,
174 			void *astarg);
175 
176 	/*
177 	 * Call the underlying dlm unlock function.  The ->dlm_unlock()
178 	 * function should convert the flags as appropriate.
179 	 *
180 	 * The unlock ast is not passed, as the stack will want to wrap
181 	 * it before calling stack->sp_proto->lp_unlock_ast().
182 	 */
183 	int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
184 			  union ocfs2_dlm_lksb *lksb,
185 			  u32 flags,
186 			  void *astarg);
187 
188 	/*
189 	 * Return the status of the current lock status block.  The fs
190 	 * code should never dereference the union.  The ->lock_status()
191 	 * callback pulls out the stack-specific lksb, converts the status
192 	 * to a proper errno, and returns it.
193 	 */
194 	int (*lock_status)(union ocfs2_dlm_lksb *lksb);
195 
196 	/*
197 	 * Pull the lvb pointer off of the stack-specific lksb.
198 	 */
199 	void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
200 
201 	/*
202 	 * This is an optoinal debugging hook.  If provided, the
203 	 * stack can dump debugging information about this lock.
204 	 */
205 	void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
206 };
207 
208 /*
209  * Each stack plugin must describe itself by registering a
210  * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
211  * stack driver.
212  */
213 struct ocfs2_stack_plugin {
214 	char *sp_name;
215 	struct ocfs2_stack_operations *sp_ops;
216 	struct module *sp_owner;
217 
218 	/* These are managed by the stackglue code. */
219 	struct list_head sp_list;
220 	unsigned int sp_count;
221 	struct ocfs2_locking_protocol *sp_proto;
222 };
223 
224 
225 /* Used by the filesystem */
226 int ocfs2_cluster_connect(const char *stack_name,
227 			  const char *group,
228 			  int grouplen,
229 			  void (*recovery_handler)(int node_num,
230 						   void *recovery_data),
231 			  void *recovery_data,
232 			  struct ocfs2_cluster_connection **conn);
233 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
234 			     int hangup_pending);
235 void ocfs2_cluster_hangup(const char *group, int grouplen);
236 int ocfs2_cluster_this_node(unsigned int *node);
237 
238 struct ocfs2_lock_res;
239 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
240 		   int mode,
241 		   union ocfs2_dlm_lksb *lksb,
242 		   u32 flags,
243 		   void *name,
244 		   unsigned int namelen,
245 		   struct ocfs2_lock_res *astarg);
246 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
247 		     union ocfs2_dlm_lksb *lksb,
248 		     u32 flags,
249 		     struct ocfs2_lock_res *astarg);
250 
251 int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
252 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
253 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
254 
255 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
256 
257 
258 /* Used by stack plugins */
259 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
260 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
261 #endif  /* STACKGLUE_H */
262