1 /* $NetBSD: umount_linux.c,v 1.1.1.2 2009/03/20 20:26:52 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1997-2009 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. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgment: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * 42 * File: am-utils/conf/umount/umount_linux.c 43 * 44 */ 45 46 /* 47 * Linux method of unmounting filesystems: if umount(2) failed with EIO or 48 * ESTALE, try umount2(2) with MNT_FORCE+MNT_DETACH. 49 */ 50 51 #ifdef HAVE_CONFIG_H 52 # include <config.h> 53 #endif /* HAVE_CONFIG_H */ 54 #include <am_defs.h> 55 #include <amu.h> 56 57 58 int 59 umount_fs(char *mntdir, const char *mnttabname, u_int unmount_flags) 60 { 61 mntlist *mlist, *mp, *mp_save = NULL; 62 int error = 0; 63 #ifdef HAVE_LOOP_DEVICE 64 char *opt, *xopts = NULL; 65 char loopstr[] = "loop="; 66 char *loopdev; 67 #endif /* HAVE_LOOP_DEVICE */ 68 69 mp = mlist = read_mtab(mntdir, mnttabname); 70 71 /* 72 * Search the mount table looking for 73 * the correct (ie last) matching entry 74 */ 75 while (mp) { 76 if (STREQ(mp->mnt->mnt_dir, mntdir)) 77 mp_save = mp; 78 mp = mp->mnext; 79 } 80 81 if (!mp_save) { 82 plog(XLOG_ERROR, "Couldn't find how to unmount %s", mntdir); 83 /* Assume it is already unmounted */ 84 error = 0; 85 goto out; 86 } 87 88 dlog("Trying unmount(%s)", mp_save->mnt->mnt_dir); 89 90 #ifdef MOUNT_TABLE_ON_FILE 91 /* 92 * This unmount may hang leaving this process with an exclusive lock on 93 * /etc/mtab. Therefore it is necessary to unlock mtab, do the unmount, 94 * then lock mtab (again) and reread it and finally update it. 95 */ 96 unlock_mntlist(); 97 #endif /* MOUNT_TABLE_ON_FILE */ 98 99 #if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH) 100 /* 101 * If user asked to try forced unmounts, then do a quick check to see if 102 * the mount point is hung badly. If so, then try to detach it by 103 * force; if the latter works, we're done. 104 */ 105 if (unmount_flags & AMU_UMOUNT_DETACH) { 106 /* 107 * Note: we pass both DETACH and FORCE flags, because umount2_fs below 108 * (on Linux), should try FORCE before DETACH (the latter always 109 * succeeds). 110 */ 111 error = umount2_fs(mp_save->mnt->mnt_dir, 112 unmount_flags & (AMU_UMOUNT_DETACH|AMU_UMOUNT_FORCE)); 113 } else 114 #endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH) */ 115 error = UNMOUNT_TRAP(mp_save->mnt); 116 if (error < 0) { 117 plog(XLOG_WARNING, "unmount(%s) failed: %m", mp_save->mnt->mnt_dir); 118 switch ((error = errno)) { 119 case EINVAL: 120 case ENOTBLK: 121 plog(XLOG_WARNING, "unmount: %s is not mounted", mp_save->mnt->mnt_dir); 122 error = 0; /* Not really an error */ 123 break; 124 125 case ENOENT: 126 /* 127 * This could happen if the kernel insists on following symlinks 128 * when we try to unmount a direct mountpoint. We need to propagate 129 * the error up so that the top layers know it failed and don't 130 * try to rmdir() the mountpoint or other silly things. 131 */ 132 plog(XLOG_ERROR, "mount point %s: %m", mp_save->mnt->mnt_dir); 133 break; 134 135 #if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE) 136 case EBUSY: 137 /* 138 * Caller determines if forced unmounts should be used now (for 139 * EBUSY). If caller asked to force an unmount, *and* the above 140 * "trivial" unmount attempt failed with EBUSY, then try to force 141 * the unmount. 142 */ 143 if (unmount_flags & AMU_UMOUNT_FORCE) { 144 error = umount2_fs(mp_save->mnt->mnt_dir, 145 unmount_flags & AMU_UMOUNT_FORCE); 146 if (error < 0) { 147 plog(XLOG_WARNING, "%s: unmount/force: %m", 148 mp_save->mnt->mnt_dir); 149 error = errno; 150 } 151 } 152 break; 153 #endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE) */ 154 155 default: 156 dlog("%s: unmount: %m", mp_save->mnt->mnt_dir); 157 break; 158 } 159 } else { 160 dlog("unmount(%s) succeeded", mp_save->mnt->mnt_dir); 161 } 162 dlog("Finished unmount(%s)", mp_save->mnt->mnt_dir); 163 164 /* 165 * If we are successful or there was an ENOENT, remove 166 * the mount entry from the mtab file. 167 */ 168 if (error && error != ENOENT) 169 goto out; 170 171 #ifdef HAVE_LOOP_DEVICE 172 /* look for loop=/dev/loopX in mnt_opts */ 173 xopts = strdup(mp_save->mnt->mnt_opts); /* b/c strtok is destructive */ 174 for (opt = strtok(xopts, ","); opt; opt = strtok(NULL, ",")) 175 if (NSTREQ(opt, loopstr, sizeof(loopstr) - 1)) { 176 loopdev = opt + sizeof(loopstr) - 1; 177 if (delete_loop_device(loopdev) < 0) 178 plog(XLOG_WARNING, "unmount() failed to release loop device %s: %m", loopdev); 179 else 180 plog(XLOG_INFO, "unmount() released loop device %s OK", loopdev); 181 break; 182 } 183 if (xopts) 184 XFREE(xopts); 185 #endif /* HAVE_LOOP_DEVICE */ 186 187 #ifdef MOUNT_TABLE_ON_FILE 188 free_mntlist(mlist); 189 mp = mlist = read_mtab(mntdir, mnttabname); 190 191 /* 192 * Search the mount table looking for 193 * the correct (ie last) matching entry 194 */ 195 mp_save = NULL; 196 while (mp) { 197 if (STREQ(mp->mnt->mnt_dir, mntdir)) 198 mp_save = mp; 199 mp = mp->mnext; 200 } 201 202 if (mp_save) { 203 mnt_free(mp_save->mnt); 204 mp_save->mnt = NULL; 205 rewrite_mtab(mlist, mnttabname); 206 } 207 #endif /* MOUNT_TABLE_ON_FILE */ 208 209 out: 210 free_mntlist(mlist); 211 212 return error; 213 } 214 215 216 #if defined(HAVE_UMOUNT2) && (defined(MNT2_GEN_OPT_FORCE) || defined(MNT2_GEN_OPT_DETACH)) 217 /* 218 * Force unmount, no questions asked, without touching mnttab file. Try 219 * detach first because it is safer: will remove the hung mnt point without 220 * affecting hung applications. "Force" is more risky: it will cause the 221 * kernel to return EIO to applications stuck on a stat(2) of Amd. 222 */ 223 int 224 umount2_fs(const char *mntdir, u_int unmount_flags) 225 { 226 int error = 0; 227 228 #ifdef MNT2_GEN_OPT_DETACH 229 if (unmount_flags & AMU_UMOUNT_DETACH) { 230 error = umount2(mntdir, MNT2_GEN_OPT_DETACH); 231 if (error < 0 && (errno == EINVAL || errno == ENOENT)) 232 error = 0; /* ignore EINVAL/ENOENT */ 233 if (error < 0) { /* don't try FORCE if detach succeeded */ 234 plog(XLOG_WARNING, "%s: unmount/detach: %m", mntdir); 235 /* fall through to try "force" (if flag specified) */ 236 } else { 237 dlog("%s: unmount/detach: OK", mntdir); 238 return error; 239 } 240 } 241 #endif /* MNT2_GEN_OPT_DETACH */ 242 243 #ifdef MNT2_GEN_OPT_FORCE 244 if (unmount_flags & AMU_UMOUNT_FORCE) { 245 plog(XLOG_INFO, "umount2_fs: trying unmount/forced on %s", mntdir); 246 error = umount2(mntdir, MNT2_GEN_OPT_FORCE); 247 if (error < 0 && (errno == EINVAL || errno == ENOENT)) 248 error = 0; /* ignore EINVAL/ENOENT */ 249 if (error < 0) 250 plog(XLOG_WARNING, "%s: unmount/force: %m", mntdir); 251 else 252 dlog("%s: unmount/force: OK", mntdir); 253 /* fall through to return whatever error we got (if any) */ 254 } 255 #endif /* MNT2_GEN_OPT_FORCE */ 256 257 return error; 258 } 259 #endif /* HAVE_UMOUNT2 && (MNT2_GEN_OPT_FORCE || MNT2_GEN_OPT_DETACH) */ 260