1 /* $NetBSD: umount_linux.c,v 1.1.1.3 2015/01/17 16:34:16 christos Exp $ */
2
3 /*
4 * Copyright (c) 1997-2014 Erez Zadok
5 * Copyright (c) 1990 Jan-Simon Pendry
6 * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
7 * Copyright (c) 1990 The Regents of the University of California.
8 * All rights reserved.
9 *
10 * This code is derived from software contributed to Berkeley by
11 * Jan-Simon Pendry at Imperial College, London.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 *
38 * File: am-utils/conf/umount/umount_linux.c
39 *
40 */
41
42 /*
43 * Linux method of unmounting filesystems: if umount(2) failed with EIO or
44 * ESTALE, try umount2(2) with MNT_FORCE+MNT_DETACH.
45 */
46
47 #ifdef HAVE_CONFIG_H
48 # include <config.h>
49 #endif /* HAVE_CONFIG_H */
50 #include <am_defs.h>
51 #include <amu.h>
52
53
54 int
umount_fs(char * mntdir,const char * mnttabname,u_int unmount_flags)55 umount_fs(char *mntdir, const char *mnttabname, u_int unmount_flags)
56 {
57 mntlist *mlist, *mp, *mp_save = NULL;
58 int error = 0;
59 #ifdef HAVE_LOOP_DEVICE
60 char *opt, *xopts = NULL;
61 char loopstr[] = "loop=";
62 char *loopdev;
63 #endif /* HAVE_LOOP_DEVICE */
64 unsigned int retries = 8;
65
66 mp = mlist = read_mtab(mntdir, mnttabname);
67
68 /*
69 * Search the mount table looking for
70 * the correct (ie last) matching entry
71 */
72 while (mp) {
73 if (STREQ(mp->mnt->mnt_dir, mntdir))
74 mp_save = mp;
75 mp = mp->mnext;
76 }
77
78 if (!mp_save) {
79 plog(XLOG_ERROR, "Couldn't find how to unmount %s", mntdir);
80 /* Assume it is already unmounted */
81 error = 0;
82 goto out;
83 }
84
85 plog(XLOG_ERROR, "Trying unmount %s, umount_flags 0x%x", mp_save->mnt->mnt_dir, unmount_flags);
86 dlog("Trying unmount(%s)", mp_save->mnt->mnt_dir);
87
88 #ifdef MOUNT_TABLE_ON_FILE
89 /*
90 * This unmount may hang leaving this process with an exclusive lock on
91 * /etc/mtab. Therefore it is necessary to unlock mtab, do the unmount,
92 * then lock mtab (again) and reread it and finally update it.
93 */
94 unlock_mntlist();
95 #endif /* MOUNT_TABLE_ON_FILE */
96
97 again:
98 #if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH)
99 /*
100 * If user asked to try forced unmounts, then do a quick check to see if
101 * the mount point is hung badly. If so, then try to detach it by
102 * force; if the latter works, we're done.
103 */
104 if (unmount_flags & AMU_UMOUNT_DETACH) {
105 /*
106 * Note: we pass both DETACH and FORCE flags, because umount2_fs below
107 * (on Linux), should try FORCE before DETACH (the latter always
108 * succeeds).
109 */
110 error = umount2_fs(mp_save->mnt->mnt_dir,
111 unmount_flags & (AMU_UMOUNT_DETACH|AMU_UMOUNT_FORCE));
112 } else
113 #endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH) */
114 error = UNMOUNT_TRAP(mp_save->mnt);
115
116 /* Linux kernel can be sluggish for some reason */
117 if (error == EBUSY && retries--) {
118 struct timespec tm = {0, 200000000};
119 nanosleep(&tm, NULL);
120 goto again;
121 }
122
123 if (error < 0) {
124 plog(XLOG_WARNING, "unmount(%s) failed: %m", mp_save->mnt->mnt_dir);
125 switch ((error = errno)) {
126 case EINVAL:
127 case ENOTBLK:
128 plog(XLOG_WARNING, "unmount: %s is not mounted", mp_save->mnt->mnt_dir);
129 error = 0; /* Not really an error */
130 break;
131
132 case ENOENT:
133 /*
134 * This could happen if the kernel insists on following symlinks
135 * when we try to unmount a direct mountpoint. We need to propagate
136 * the error up so that the top layers know it failed and don't
137 * try to rmdir() the mountpoint or other silly things.
138 */
139 plog(XLOG_ERROR, "mount point %s: %m", mp_save->mnt->mnt_dir);
140 break;
141
142 #if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE)
143 case EBUSY:
144 /*
145 * Caller determines if forced unmounts should be used now (for
146 * EBUSY). If caller asked to force an unmount, *and* the above
147 * "trivial" unmount attempt failed with EBUSY, then try to force
148 * the unmount.
149 */
150 if (unmount_flags & AMU_UMOUNT_FORCE) {
151 error = umount2_fs(mp_save->mnt->mnt_dir,
152 unmount_flags & AMU_UMOUNT_FORCE);
153 if (error < 0) {
154 plog(XLOG_WARNING, "%s: unmount/force: %m",
155 mp_save->mnt->mnt_dir);
156 error = errno;
157 }
158 }
159 break;
160 #endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE) */
161
162 default:
163 dlog("%s: unmount: %m", mp_save->mnt->mnt_dir);
164 break;
165 }
166 } else {
167 dlog("unmount(%s) succeeded", mp_save->mnt->mnt_dir);
168 }
169 dlog("Finished unmount(%s)", mp_save->mnt->mnt_dir);
170
171 /*
172 * If we are successful or there was an ENOENT, remove
173 * the mount entry from the mtab file.
174 */
175 if (error && error != ENOENT)
176 goto out;
177
178 #ifdef HAVE_LOOP_DEVICE
179 /* look for loop=/dev/loopX in mnt_opts */
180 xopts = xstrdup(mp_save->mnt->mnt_opts); /* b/c strtok is destructive */
181 for (opt = strtok(xopts, ","); opt; opt = strtok(NULL, ","))
182 if (NSTREQ(opt, loopstr, sizeof(loopstr) - 1)) {
183 loopdev = opt + sizeof(loopstr) - 1;
184 if (delete_loop_device(loopdev) < 0)
185 plog(XLOG_WARNING, "unmount() failed to release loop device %s: %m", loopdev);
186 else
187 plog(XLOG_INFO, "unmount() released loop device %s OK", loopdev);
188 break;
189 }
190 if (xopts)
191 XFREE(xopts);
192 #endif /* HAVE_LOOP_DEVICE */
193
194 #ifdef MOUNT_TABLE_ON_FILE
195 free_mntlist(mlist);
196 mp = mlist = read_mtab(mntdir, mnttabname);
197
198 /*
199 * Search the mount table looking for
200 * the correct (ie last) matching entry
201 */
202 mp_save = NULL;
203 while (mp) {
204 if (STREQ(mp->mnt->mnt_dir, mntdir))
205 mp_save = mp;
206 mp = mp->mnext;
207 }
208
209 if (mp_save) {
210 mnt_free(mp_save->mnt);
211 mp_save->mnt = NULL;
212 rewrite_mtab(mlist, mnttabname);
213 }
214 #endif /* MOUNT_TABLE_ON_FILE */
215
216 out:
217 free_mntlist(mlist);
218
219 return error;
220 }
221
222
223 #if defined(HAVE_UMOUNT2) && (defined(MNT2_GEN_OPT_FORCE) || defined(MNT2_GEN_OPT_DETACH))
224 /*
225 * Force unmount, no questions asked, without touching mnttab file. Try
226 * detach first because it is safer: will remove the hung mnt point without
227 * affecting hung applications. "Force" is more risky: it will cause the
228 * kernel to return EIO to applications stuck on a stat(2) of Amd.
229 */
230 int
umount2_fs(const char * mntdir,u_int unmount_flags)231 umount2_fs(const char *mntdir, u_int unmount_flags)
232 {
233 int error = 0;
234
235 #ifdef MNT2_GEN_OPT_DETACH
236 if (unmount_flags & AMU_UMOUNT_DETACH) {
237 error = umount2(mntdir, MNT2_GEN_OPT_DETACH);
238 if (error < 0 && (errno == EINVAL || errno == ENOENT))
239 error = 0; /* ignore EINVAL/ENOENT */
240 if (error < 0) { /* don't try FORCE if detach succeeded */
241 plog(XLOG_WARNING, "%s: unmount/detach: %m", mntdir);
242 /* fall through to try "force" (if flag specified) */
243 } else {
244 dlog("%s: unmount/detach: OK", mntdir);
245 return error;
246 }
247 }
248 #endif /* MNT2_GEN_OPT_DETACH */
249
250 #ifdef MNT2_GEN_OPT_FORCE
251 if (unmount_flags & AMU_UMOUNT_FORCE) {
252 plog(XLOG_INFO, "umount2_fs: trying unmount/forced on %s", mntdir);
253 error = umount2(mntdir, MNT2_GEN_OPT_FORCE);
254 if (error < 0 && (errno == EINVAL || errno == ENOENT))
255 error = 0; /* ignore EINVAL/ENOENT */
256 if (error < 0)
257 plog(XLOG_WARNING, "%s: unmount/force: %m", mntdir);
258 else
259 dlog("%s: unmount/force: OK", mntdir);
260 /* fall through to return whatever error we got (if any) */
261 }
262 #endif /* MNT2_GEN_OPT_FORCE */
263
264 return error;
265 }
266 #endif /* HAVE_UMOUNT2 && (MNT2_GEN_OPT_FORCE || MNT2_GEN_OPT_DETACH) */
267