1/*
2   Unix SMB/CIFS implementation.
3   kernel oplock processing for Linux
4   Copyright (C) Andrew Tridgell 2000
5
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3 of the License, or
9   (at your option) any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program.  If not, see <http://www.gnu.org/licenses/>.
18*/
19
20#define DBGC_CLASS DBGC_LOCKING
21#include "includes.h"
22#include "smbd/globals.h"
23
24#if HAVE_KERNEL_OPLOCKS_LINUX
25
26#ifndef F_SETLEASE
27#define F_SETLEASE	1024
28#endif
29
30#ifndef F_GETLEASE
31#define F_GETLEASE	1025
32#endif
33
34#ifndef CAP_LEASE
35#define CAP_LEASE 28
36#endif
37
38#ifndef RT_SIGNAL_LEASE
39#define RT_SIGNAL_LEASE (SIGRTMIN+1)
40#endif
41
42#ifndef F_SETSIG
43#define F_SETSIG 10
44#endif
45
46/*
47 * public function to get linux lease capability. Needed by some VFS modules (eg. gpfs.c)
48 */
49void linux_set_lease_capability(void)
50{
51	set_effective_capability(LEASE_CAPABILITY);
52}
53
54/*
55 * Call to set the kernel lease signal handler
56 */
57int linux_set_lease_sighandler(int fd)
58{
59        if (fcntl(fd, F_SETSIG, RT_SIGNAL_LEASE) == -1) {
60                DEBUG(3,("Failed to set signal handler for kernel lease\n"));
61                return -1;
62        }
63
64	return 0;
65}
66
67/****************************************************************************
68 Call SETLEASE. If we get EACCES then we try setting up the right capability and
69 try again.
70 Use the SMB_VFS_LINUX_SETLEASE instead of this call directly.
71****************************************************************************/
72
73int linux_setlease(int fd, int leasetype)
74{
75	int ret;
76
77	ret = fcntl(fd, F_SETLEASE, leasetype);
78	if (ret == -1 && errno == EACCES) {
79		set_effective_capability(LEASE_CAPABILITY);
80		ret = fcntl(fd, F_SETLEASE, leasetype);
81	}
82
83	return ret;
84}
85
86/****************************************************************************
87 * Deal with the Linux kernel <--> smbd
88 * oplock break protocol.
89****************************************************************************/
90
91static void linux_oplock_signal_handler(struct tevent_context *ev_ctx,
92					struct tevent_signal *se,
93					int signum, int count,
94					void *_info, void *private_data)
95{
96	siginfo_t *info = (siginfo_t *)_info;
97	int fd = info->si_fd;
98	files_struct *fsp;
99
100	fsp = file_find_fd(fd);
101	if (fsp == NULL) {
102		DEBUG(0,("linux_oplock_signal_handler: failed to find fsp for file fd=%d (file was closed ?)\n", fd ));
103		return;
104	}
105	break_kernel_oplock(smbd_messaging_context(), fsp);
106}
107
108/****************************************************************************
109 Attempt to set an kernel oplock on a file.
110****************************************************************************/
111
112static bool linux_set_kernel_oplock(struct kernel_oplocks *ctx,
113				    files_struct *fsp, int oplock_type)
114{
115	if ( SMB_VFS_LINUX_SETLEASE(fsp, F_WRLCK) == -1) {
116		DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, "
117			 "fd = %d, file_id = %s. (%s)\n",
118			 fsp_str_dbg(fsp), fsp->fh->fd,
119			 file_id_string_tos(&fsp->file_id),
120			 strerror(errno)));
121		return False;
122	}
123
124	DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, "
125		 "file_id = %s gen_id = %lu\n",
126		 fsp_str_dbg(fsp), file_id_string_tos(&fsp->file_id),
127		 fsp->fh->gen_id));
128
129	return True;
130}
131
132/****************************************************************************
133 Release a kernel oplock on a file.
134****************************************************************************/
135
136static void linux_release_kernel_oplock(struct kernel_oplocks *ctx,
137					files_struct *fsp, int oplock_type)
138{
139	if (DEBUGLVL(10)) {
140		/*
141		 * Check and print out the current kernel
142		 * oplock state of this file.
143		 */
144		int state = fcntl(fsp->fh->fd, F_GETLEASE, 0);
145		dbgtext("linux_release_kernel_oplock: file %s, file_id = %s "
146			"gen_id = %lu has kernel oplock state "
147			"of %x.\n", fsp_str_dbg(fsp),
148		        file_id_string_tos(&fsp->file_id),
149			fsp->fh->gen_id, state );
150	}
151
152	/*
153	 * Remove the kernel oplock on this file.
154	 */
155	if ( SMB_VFS_LINUX_SETLEASE(fsp, F_UNLCK) == -1) {
156		if (DEBUGLVL(0)) {
157			dbgtext("linux_release_kernel_oplock: Error when "
158				"removing kernel oplock on file " );
159			dbgtext("%s, file_id = %s, gen_id = %lu. "
160				"Error was %s\n", fsp_str_dbg(fsp),
161				file_id_string_tos(&fsp->file_id),
162				fsp->fh->gen_id, strerror(errno) );
163		}
164	}
165}
166
167/****************************************************************************
168 See if the kernel supports oplocks.
169****************************************************************************/
170
171static bool linux_oplocks_available(void)
172{
173	int fd, ret;
174	fd = open("/dev/null", O_RDONLY);
175	if (fd == -1)
176		return False; /* uggh! */
177	ret = fcntl(fd, F_GETLEASE, 0);
178	close(fd);
179	return ret == F_UNLCK;
180}
181
182/****************************************************************************
183 Setup kernel oplocks.
184****************************************************************************/
185
186static const struct kernel_oplocks_ops linux_koplocks = {
187	.set_oplock			= linux_set_kernel_oplock,
188	.release_oplock			= linux_release_kernel_oplock,
189	.contend_level2_oplocks_begin	= NULL,
190	.contend_level2_oplocks_end	= NULL,
191};
192
193struct kernel_oplocks *linux_init_kernel_oplocks(TALLOC_CTX *mem_ctx)
194{
195	struct kernel_oplocks *ctx;
196	struct tevent_signal *se;
197
198	if (!linux_oplocks_available()) {
199		DEBUG(3,("Linux kernel oplocks not available\n"));
200		return NULL;
201	}
202
203	ctx = talloc_zero(mem_ctx, struct kernel_oplocks);
204	if (!ctx) {
205		DEBUG(0,("Linux Kernel oplocks talloc_Zero failed\n"));
206		return NULL;
207	}
208
209	ctx->ops = &linux_koplocks;
210
211	se = tevent_add_signal(smbd_event_context(),
212			       ctx,
213			       RT_SIGNAL_LEASE, SA_SIGINFO,
214			       linux_oplock_signal_handler,
215			       ctx);
216	if (!se) {
217		DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler"));
218		TALLOC_FREE(ctx);
219		return NULL;
220	}
221
222	ctx->private_data = se;
223
224	DEBUG(3,("Linux kernel oplocks enabled\n"));
225
226	return ctx;
227}
228#else
229 void oplock_linux_dummy(void);
230
231 void oplock_linux_dummy(void) {}
232#endif /* HAVE_KERNEL_OPLOCKS_LINUX */
233