Root/fs/ocfs2/stackglue.h

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 */
32struct file;
33struct 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
49/*
50 * ocfs2_protocol_version changes when ocfs2 does something different in
51 * its inter-node behavior. See dlmglue.c for more information.
52 */
53struct ocfs2_protocol_version {
54    u8 pv_major;
55    u8 pv_minor;
56};
57
58/*
59 * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
60 * has a pointer to separately allocated lvb space. This struct exists only to
61 * include in the lksb union to make space for a combined dlm_lksb and lvb.
62 */
63struct fsdlm_lksb_plus_lvb {
64    struct dlm_lksb lksb;
65    char lvb[DLM_LVB_LEN];
66};
67
68/*
69 * A union of all lock status structures. We define it here so that the
70 * size of the union is known. Lock status structures are embedded in
71 * ocfs2 inodes.
72 */
73struct ocfs2_cluster_connection;
74struct ocfs2_dlm_lksb {
75     union {
76         struct dlm_lockstatus lksb_o2dlm;
77         struct dlm_lksb lksb_fsdlm;
78         struct fsdlm_lksb_plus_lvb padding;
79     };
80     struct ocfs2_cluster_connection *lksb_conn;
81};
82
83/*
84 * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
85 */
86struct ocfs2_locking_protocol {
87    struct ocfs2_protocol_version lp_max_version;
88    void (*lp_lock_ast)(struct ocfs2_dlm_lksb *lksb);
89    void (*lp_blocking_ast)(struct ocfs2_dlm_lksb *lksb, int level);
90    void (*lp_unlock_ast)(struct ocfs2_dlm_lksb *lksb, int error);
91};
92
93
94/*
95 * A cluster connection. Mostly opaque to ocfs2, the connection holds
96 * state for the underlying stack. ocfs2 does use cc_version to determine
97 * locking compatibility.
98 */
99struct ocfs2_cluster_connection {
100    char cc_name[GROUP_NAME_MAX];
101    int cc_namelen;
102    struct ocfs2_protocol_version cc_version;
103    struct ocfs2_locking_protocol *cc_proto;
104    void (*cc_recovery_handler)(int node_num, void *recovery_data);
105    void *cc_recovery_data;
106    void *cc_lockspace;
107    void *cc_private;
108};
109
110/*
111 * Each cluster stack implements the stack operations structure. Not used
112 * in the ocfs2 code, the stackglue code translates generic cluster calls
113 * into stack operations.
114 */
115struct ocfs2_stack_operations {
116    /*
117     * The fs code calls ocfs2_cluster_connect() to attach a new
118     * filesystem to the cluster stack. The ->connect() op is passed
119     * an ocfs2_cluster_connection with the name and recovery field
120     * filled in.
121     *
122     * The stack must set up any notification mechanisms and create
123     * the filesystem lockspace in the DLM. The lockspace should be
124     * stored on cc_lockspace. Any other information can be stored on
125     * cc_private.
126     *
127     * ->connect() must not return until it is guaranteed that
128     *
129     * - Node down notifications for the filesystem will be recieved
130     * and passed to conn->cc_recovery_handler().
131     * - Locking requests for the filesystem will be processed.
132     */
133    int (*connect)(struct ocfs2_cluster_connection *conn);
134
135    /*
136     * The fs code calls ocfs2_cluster_disconnect() when a filesystem
137     * no longer needs cluster services. All DLM locks have been
138     * dropped, and recovery notification is being ignored by the
139     * fs code. The stack must disengage from the DLM and discontinue
140     * recovery notification.
141     *
142     * Once ->disconnect() has returned, the connection structure will
143     * be freed. Thus, a stack must not return from ->disconnect()
144     * until it will no longer reference the conn pointer.
145     *
146     * Once this call returns, the stack glue will be dropping this
147     * connection's reference on the module.
148     */
149    int (*disconnect)(struct ocfs2_cluster_connection *conn);
150
151    /*
152     * ->this_node() returns the cluster's unique identifier for the
153     * local node.
154     */
155    int (*this_node)(unsigned int *node);
156
157    /*
158     * Call the underlying dlm lock function. The ->dlm_lock()
159     * callback should convert the flags and mode as appropriate.
160     *
161     * ast and bast functions are not part of the call because the
162     * stack will likely want to wrap ast and bast calls before passing
163     * them to stack->sp_proto. There is no astarg. The lksb will
164     * be passed back to the ast and bast functions. The caller can
165     * use this to find their object.
166     */
167    int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
168            int mode,
169            struct ocfs2_dlm_lksb *lksb,
170            u32 flags,
171            void *name,
172            unsigned int namelen);
173
174    /*
175     * Call the underlying dlm unlock function. The ->dlm_unlock()
176     * function should convert the flags as appropriate.
177     *
178     * The unlock ast is not passed, as the stack will want to wrap
179     * it before calling stack->sp_proto->lp_unlock_ast(). There is
180     * no astarg. The lksb will be passed back to the unlock ast
181     * function. The caller can use this to find their object.
182     */
183    int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
184              struct ocfs2_dlm_lksb *lksb,
185              u32 flags);
186
187    /*
188     * Return the status of the current lock status block. The fs
189     * code should never dereference the union. The ->lock_status()
190     * callback pulls out the stack-specific lksb, converts the status
191     * to a proper errno, and returns it.
192     */
193    int (*lock_status)(struct ocfs2_dlm_lksb *lksb);
194
195    /*
196     * Return non-zero if the LVB is valid.
197     */
198    int (*lvb_valid)(struct ocfs2_dlm_lksb *lksb);
199
200    /*
201     * Pull the lvb pointer off of the stack-specific lksb.
202     */
203    void *(*lock_lvb)(struct ocfs2_dlm_lksb *lksb);
204
205    /*
206     * Cluster-aware posix locks
207     *
208     * This is NULL for stacks which do not support posix locks.
209     */
210    int (*plock)(struct ocfs2_cluster_connection *conn,
211             u64 ino,
212             struct file *file,
213             int cmd,
214             struct file_lock *fl);
215
216    /*
217     * This is an optoinal debugging hook. If provided, the
218     * stack can dump debugging information about this lock.
219     */
220    void (*dump_lksb)(struct ocfs2_dlm_lksb *lksb);
221};
222
223/*
224 * Each stack plugin must describe itself by registering a
225 * ocfs2_stack_plugin structure. This is only seen by stackglue and the
226 * stack driver.
227 */
228struct ocfs2_stack_plugin {
229    char *sp_name;
230    struct ocfs2_stack_operations *sp_ops;
231    struct module *sp_owner;
232
233    /* These are managed by the stackglue code. */
234    struct list_head sp_list;
235    unsigned int sp_count;
236    struct ocfs2_protocol_version sp_max_proto;
237};
238
239
240/* Used by the filesystem */
241int ocfs2_cluster_connect(const char *stack_name,
242              const char *group,
243              int grouplen,
244              struct ocfs2_locking_protocol *lproto,
245              void (*recovery_handler)(int node_num,
246                           void *recovery_data),
247              void *recovery_data,
248              struct ocfs2_cluster_connection **conn);
249/*
250 * Used by callers that don't store their stack name. They must ensure
251 * all nodes have the same stack.
252 */
253int ocfs2_cluster_connect_agnostic(const char *group,
254                   int grouplen,
255                   struct ocfs2_locking_protocol *lproto,
256                   void (*recovery_handler)(int node_num,
257                                void *recovery_data),
258                   void *recovery_data,
259                   struct ocfs2_cluster_connection **conn);
260int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
261                 int hangup_pending);
262void ocfs2_cluster_hangup(const char *group, int grouplen);
263int ocfs2_cluster_this_node(unsigned int *node);
264
265struct ocfs2_lock_res;
266int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
267           int mode,
268           struct ocfs2_dlm_lksb *lksb,
269           u32 flags,
270           void *name,
271           unsigned int namelen);
272int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
273             struct ocfs2_dlm_lksb *lksb,
274             u32 flags);
275
276int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb);
277int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb);
278void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb);
279void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb);
280
281int ocfs2_stack_supports_plocks(void);
282int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
283        struct file *file, int cmd, struct file_lock *fl);
284
285void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_proto);
286
287
288/* Used by stack plugins */
289int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
290void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
291
292#endif /* STACKGLUE_H */
293

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