source: branches/samba-3.3.x/source/smbd/dmapi.c

Last change on this file was 206, checked in by Herwig Bauernfeind, 16 years ago

Import Samba 3.3 branch at 3.0.0 level (psmedley's port)
File size: 8.7 KB
Line 
1/*
2 Unix SMB/CIFS implementation.
3 DMAPI Support routines
4
5 Copyright (C) James Peach 2006
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
19*/
20
21#include "includes.h"
22
23#undef DBGC_CLASS
24#define DBGC_CLASS DBGC_DMAPI
25
26#ifndef USE_DMAPI
27
28uint32 dmapi_file_flags(const char * const path) { return 0; }
29bool dmapi_have_session(void) { return False; }
30const void * dmapi_get_current_session(void) { return NULL; }
31
32#else /* USE_DMAPI */
33
34#ifdef HAVE_XFS_DMAPI_H
35#include <xfs/dmapi.h>
36#elif defined(HAVE_SYS_DMI_H)
37#include <sys/dmi.h>
38#elif defined(HAVE_SYS_JFSDMAPI_H)
39#include <sys/jfsdmapi.h>
40#elif defined(HAVE_SYS_DMAPI_H)
41#include <sys/dmapi.h>
42#elif defined(HAVE_DMAPI_H)
43#include <dmapi.h>
44#endif
45
46#define DMAPI_SESSION_NAME "samba"
47#define DMAPI_TRACE 10
48
49static dm_sessid_t samba_dmapi_session = DM_NO_SESSION;
50static unsigned session_num;
51
52/*
53 Initialise DMAPI session. The session is persistant kernel state,
54 so it might already exist, in which case we merely want to
55 reconnect to it. This function should be called as root.
56*/
57static int dmapi_init_session(void)
58{
59 char buf[DM_SESSION_INFO_LEN];
60 size_t buflen;
61 uint nsessions = 5;
62 dm_sessid_t *sessions = NULL;
63 char *version;
64 char *session_name;
65 TALLOC_CTX *tmp_ctx = talloc_new(NULL);
66
67 int i, err;
68
69 if (session_num == 0) {
70 session_name = DMAPI_SESSION_NAME;
71 } else {
72 session_name = talloc_asprintf(tmp_ctx, "%s%u", DMAPI_SESSION_NAME,
73 session_num);
74 }
75
76 if (session_name == NULL) {
77 DEBUG(0,("Out of memory in dmapi_init_session\n"));
78 talloc_free(tmp_ctx);
79 return -1;
80 }
81
82
83 if (dm_init_service(&version) < 0) {
84 DEBUG(0, ("dm_init_service failed - disabling DMAPI\n"));
85 talloc_free(tmp_ctx);
86 return -1;
87 }
88
89 ZERO_STRUCT(buf);
90
91 /* Fetch kernel DMAPI sessions until we get any of them */
92 do {
93 dm_sessid_t *new_sessions;
94 nsessions *= 2;
95 new_sessions = TALLOC_REALLOC_ARRAY(tmp_ctx, sessions,
96 dm_sessid_t, nsessions);
97 if (new_sessions == NULL) {
98 talloc_free(tmp_ctx);
99 return -1;
100 }
101
102 sessions = new_sessions;
103 err = dm_getall_sessions(nsessions, sessions, &nsessions);
104 } while (err == -1 && errno == E2BIG);
105
106 if (err == -1) {
107 DEBUGADD(DMAPI_TRACE,
108 ("failed to retrieve DMAPI sessions: %s\n",
109 strerror(errno)));
110 talloc_free(tmp_ctx);
111 return -1;
112 }
113
114 /* Look through existing kernel DMAPI sessions to find out ours */
115 for (i = 0; i < nsessions; ++i) {
116 err = dm_query_session(sessions[i], sizeof(buf), buf, &buflen);
117 buf[sizeof(buf) - 1] = '\0';
118 if (err == 0 && strcmp(session_name, buf) == 0) {
119 samba_dmapi_session = sessions[i];
120 DEBUGADD(DMAPI_TRACE,
121 ("attached to existing DMAPI session "
122 "named '%s'\n", buf));
123 break;
124 }
125 }
126
127 /* No session already defined. */
128 if (samba_dmapi_session == DM_NO_SESSION) {
129 err = dm_create_session(DM_NO_SESSION,
130 session_name,
131 &samba_dmapi_session);
132 if (err < 0) {
133 DEBUGADD(DMAPI_TRACE,
134 ("failed to create new DMAPI session: %s\n",
135 strerror(errno)));
136 samba_dmapi_session = DM_NO_SESSION;
137 talloc_free(tmp_ctx);
138 return -1;
139 }
140
141 DEBUG(0, ("created new DMAPI session named '%s' for %s\n",
142 session_name, version));
143 }
144
145 if (samba_dmapi_session != DM_NO_SESSION) {
146 set_effective_capability(DMAPI_ACCESS_CAPABILITY);
147 }
148
149 /*
150 Note that we never end the DMAPI session. It gets re-used if possiblie.
151 DMAPI session is a kernel resource that is usually lives until server reboot
152 and doesn't get destroed when an application finishes.
153
154 However, we free list of references to DMAPI sessions we've got from the kernel
155 as it is not needed anymore once we have found (or created) our session.
156 */
157
158 talloc_free(tmp_ctx);
159 return 0;
160}
161
162/*
163 Return a pointer to our DMAPI session, if available.
164 This assumes that you have called dmapi_have_session() first.
165*/
166const void *dmapi_get_current_session(void)
167{
168 if (samba_dmapi_session == DM_NO_SESSION) {
169 return NULL;
170 }
171
172 return (void *)&samba_dmapi_session;
173}
174
175/*
176 dmapi_have_session() must be the first DMAPI call you make in Samba. It will
177 initialize DMAPI, if available, and tell you if you can get a DMAPI session.
178 This should be called in the client-specific child process.
179*/
180
181bool dmapi_have_session(void)
182{
183 static bool initialized;
184 if (!initialized) {
185 initialized = true;
186
187 become_root();
188 dmapi_init_session();
189 unbecome_root();
190
191 }
192
193 return samba_dmapi_session != DM_NO_SESSION;
194}
195
196/*
197 only call this when you get back an EINVAL error indicating that the
198 session you are using is invalid. This destroys the existing session
199 and creates a new one.
200 */
201bool dmapi_new_session(void)
202{
203 if (dmapi_have_session()) {
204 /* try to destroy the old one - this may not succeed */
205 dm_destroy_session(samba_dmapi_session);
206 }
207 samba_dmapi_session = DM_NO_SESSION;
208 become_root();
209 session_num++;
210 dmapi_init_session();
211 unbecome_root();
212 return samba_dmapi_session != DM_NO_SESSION;
213}
214
215/*
216 only call this when exiting from master smbd process. DMAPI sessions
217 are long-lived kernel resources we ought to share across smbd processes.
218 However, we must free them when all smbd processes are finished to
219 allow other subsystems clean up properly. Not freeing DMAPI session
220 blocks certain HSM implementations from proper shutdown.
221*/
222bool dmapi_destroy_session(void)
223{
224 if (samba_dmapi_session != DM_NO_SESSION) {
225 become_root();
226 if (0 == dm_destroy_session(samba_dmapi_session)) {
227 session_num--;
228 samba_dmapi_session = DM_NO_SESSION;
229 } else {
230 DEBUG(0,("Couldn't destroy DMAPI session: %s\n",
231 strerror(errno)));
232 }
233 unbecome_root();
234 }
235 return samba_dmapi_session == DM_NO_SESSION;
236}
237
238
239/*
240 This is default implementation of dmapi_file_flags() that is
241 called from VFS is_offline() call to know whether file is offline.
242 For GPFS-specific version see modules/vfs_tsmsm.c. It might be
243 that approach on quering existence of a specific attribute that
244 is used in vfs_tsmsm.c will work with other DMAPI-based HSM
245 implementations as well.
246*/
247uint32 dmapi_file_flags(const char * const path)
248{
249 int err;
250 dm_eventset_t events = {0};
251 uint nevents;
252
253 dm_sessid_t dmapi_session;
254 const void *dmapi_session_ptr;
255 void *dm_handle = NULL;
256 size_t dm_handle_len = 0;
257
258 uint32 flags = 0;
259
260 dmapi_session_ptr = dmapi_get_current_session();
261 if (dmapi_session_ptr == NULL) {
262 return 0;
263 }
264
265 dmapi_session = *(dm_sessid_t *)dmapi_session_ptr;
266 if (dmapi_session == DM_NO_SESSION) {
267 return 0;
268 }
269
270 /* AIX has DMAPI but no POSIX capablities support. In this case,
271 * we need to be root to do DMAPI manipulations.
272 */
273#ifndef HAVE_POSIX_CAPABILITIES
274 become_root();
275#endif
276
277 err = dm_path_to_handle(CONST_DISCARD(char *, path),
278 &dm_handle, &dm_handle_len);
279 if (err < 0) {
280 DEBUG(DMAPI_TRACE, ("dm_path_to_handle(%s): %s\n",
281 path, strerror(errno)));
282
283 if (errno != EPERM) {
284 goto done;
285 }
286
287 /* Linux capabilities are broken in that changing our
288 * user ID will clobber out effective capabilities irrespective
289 * of whether we have set PR_SET_KEEPCAPS. Fortunately, the
290 * capabilities are not removed from our permitted set, so we
291 * can re-acquire them if necessary.
292 */
293
294 set_effective_capability(DMAPI_ACCESS_CAPABILITY);
295
296 err = dm_path_to_handle(CONST_DISCARD(char *, path),
297 &dm_handle, &dm_handle_len);
298 if (err < 0) {
299 DEBUG(DMAPI_TRACE,
300 ("retrying dm_path_to_handle(%s): %s\n",
301 path, strerror(errno)));
302 goto done;
303 }
304 }
305
306 err = dm_get_eventlist(dmapi_session, dm_handle, dm_handle_len,
307 DM_NO_TOKEN, DM_EVENT_MAX, &events, &nevents);
308 if (err < 0) {
309 DEBUG(DMAPI_TRACE, ("dm_get_eventlist(%s): %s\n",
310 path, strerror(errno)));
311 dm_handle_free(dm_handle, dm_handle_len);
312 goto done;
313 }
314
315 /* We figure that the only reason a DMAPI application would be
316 * interested in trapping read events is that part of the file is
317 * offline.
318 */
319 DEBUG(DMAPI_TRACE, ("DMAPI event list for %s\n", path));
320 if (DMEV_ISSET(DM_EVENT_READ, events)) {
321 flags = FILE_ATTRIBUTE_OFFLINE;
322 }
323
324 dm_handle_free(dm_handle, dm_handle_len);
325
326 if (flags & FILE_ATTRIBUTE_OFFLINE) {
327 DEBUG(DMAPI_TRACE, ("%s is OFFLINE\n", path));
328 }
329
330done:
331
332#ifndef HAVE_POSIX_CAPABILITIES
333 unbecome_root();
334#endif
335
336 return flags;
337}
338
339
340#endif /* USE_DMAPI */
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