external/bsd/am-utils/dist/conf/umount/umount_linux.c

   1 /*      $NetBSD$        */
   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) */