/* $NetBSD: umount_linux.c,v 1.1.1.3 2015/01/17 16:34:16 christos Exp $ */
/*
* Copyright (c) 1997-2014 Erez Zadok
* Copyright (c) 1990 Jan-Simon Pendry
* Copyright (c) 1990 Imperial College of Science, Technology & Medicine
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry at Imperial College, London.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*
* File: am-utils/conf/umount/umount_linux.c
*
*/
/*
* Linux method of unmounting filesystems: if umount(2) failed with EIO or
* ESTALE, try umount2(2) with MNT_FORCE+MNT_DETACH.
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */
#include <am_defs.h>
#include <amu.h>
int
umount_fs(char *mntdir, const char *mnttabname, u_int unmount_flags)
{
mntlist *mlist, *mp, *mp_save = NULL;
int error = 0;
#ifdef HAVE_LOOP_DEVICE
char *opt, *xopts = NULL;
char loopstr[] = "loop=";
char *loopdev;
#endif /* HAVE_LOOP_DEVICE */
unsigned int retries = 8;
mp = mlist = read_mtab(mntdir, mnttabname);
/*
* Search the mount table looking for
* the correct (ie last) matching entry
*/
while (mp) {
if (STREQ(mp->mnt->mnt_dir, mntdir))
mp_save = mp;
mp = mp->mnext;
}
if (!mp_save) {
plog(XLOG_ERROR, "Couldn't find how to unmount %s", mntdir);
/* Assume it is already unmounted */
error = 0;
goto out;
}
plog(XLOG_ERROR, "Trying unmount %s, umount_flags 0x%x", mp_save->mnt->mnt_dir, unmount_flags);
dlog("Trying unmount(%s)", mp_save->mnt->mnt_dir);
#ifdef MOUNT_TABLE_ON_FILE
/*
* This unmount may hang leaving this process with an exclusive lock on
* /etc/mtab. Therefore it is necessary to unlock mtab, do the unmount,
* then lock mtab (again) and reread it and finally update it.
*/
unlock_mntlist();
#endif /* MOUNT_TABLE_ON_FILE */
again:
#if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH)
/*
* If user asked to try forced unmounts, then do a quick check to see if
* the mount point is hung badly. If so, then try to detach it by
* force; if the latter works, we're done.
*/
if (unmount_flags & AMU_UMOUNT_DETACH) {
/*
* Note: we pass both DETACH and FORCE flags, because umount2_fs below
* (on Linux), should try FORCE before DETACH (the latter always
* succeeds).
*/
error = umount2_fs(mp_save->mnt->mnt_dir,
unmount_flags & (AMU_UMOUNT_DETACH|AMU_UMOUNT_FORCE));
} else
#endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH) */
error = UNMOUNT_TRAP(mp_save->mnt);
/* Linux kernel can be sluggish for some reason */
if (error == EBUSY && retries--) {
struct timespec tm = {0, 200000000};
nanosleep(&tm, NULL);
goto again;
}
if (error < 0) {
plog(XLOG_WARNING, "unmount(%s) failed: %m", mp_save->mnt->mnt_dir);
switch ((error = errno)) {
case EINVAL:
case ENOTBLK:
plog(XLOG_WARNING, "unmount: %s is not mounted", mp_save->mnt->mnt_dir);
error = 0; /* Not really an error */
break;
case ENOENT:
/*
* This could happen if the kernel insists on following symlinks
* when we try to unmount a direct mountpoint. We need to propagate
* the error up so that the top layers know it failed and don't
* try to rmdir() the mountpoint or other silly things.
*/
plog(XLOG_ERROR, "mount point %s: %m", mp_save->mnt->mnt_dir);
break;
#if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE)
case EBUSY:
/*
* Caller determines if forced unmounts should be used now (for
* EBUSY). If caller asked to force an unmount, *and* the above
* "trivial" unmount attempt failed with EBUSY, then try to force
* the unmount.
*/
if (unmount_flags & AMU_UMOUNT_FORCE) {
error = umount2_fs(mp_save->mnt->mnt_dir,
unmount_flags & AMU_UMOUNT_FORCE);
if (error < 0) {
plog(XLOG_WARNING, "%s: unmount/force: %m",
mp_save->mnt->mnt_dir);
error = errno;
}
}
break;
#endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE) */
default:
dlog("%s: unmount: %m", mp_save->mnt->mnt_dir);
break;
}
} else {
dlog("unmount(%s) succeeded", mp_save->mnt->mnt_dir);
}
dlog("Finished unmount(%s)", mp_save->mnt->mnt_dir);
/*
* If we are successful or there was an ENOENT, remove
* the mount entry from the mtab file.
*/
if (error && error != ENOENT)
goto out;
#ifdef HAVE_LOOP_DEVICE
/* look for loop=/dev/loopX in mnt_opts */
xopts = xstrdup(mp_save->mnt->mnt_opts); /* b/c strtok is destructive */
for (opt = strtok(xopts, ","); opt; opt = strtok(NULL, ","))
if (NSTREQ(opt, loopstr, sizeof(loopstr) - 1)) {
loopdev = opt + sizeof(loopstr) - 1;
if (delete_loop_device(loopdev) < 0)
plog(XLOG_WARNING, "unmount() failed to release loop device %s: %m", loopdev);
else
plog(XLOG_INFO, "unmount() released loop device %s OK", loopdev);
break;
}
if (xopts)
XFREE(xopts);
#endif /* HAVE_LOOP_DEVICE */
#ifdef MOUNT_TABLE_ON_FILE
free_mntlist(mlist);
mp = mlist = read_mtab(mntdir, mnttabname);
/*
* Search the mount table looking for
* the correct (ie last) matching entry
*/
mp_save = NULL;
while (mp) {
if (STREQ(mp->mnt->mnt_dir, mntdir))
mp_save = mp;
mp = mp->mnext;
}
if (mp_save) {
mnt_free(mp_save->mnt);
mp_save->mnt = NULL;
rewrite_mtab(mlist, mnttabname);
}
#endif /* MOUNT_TABLE_ON_FILE */
out:
free_mntlist(mlist);
return error;
}
#if defined(HAVE_UMOUNT2) && (defined(MNT2_GEN_OPT_FORCE) || defined(MNT2_GEN_OPT_DETACH))
/*
* Force unmount, no questions asked, without touching mnttab file. Try
* detach first because it is safer: will remove the hung mnt point without
* affecting hung applications. "Force" is more risky: it will cause the
* kernel to return EIO to applications stuck on a stat(2) of Amd.
*/
int
umount2_fs(const char *mntdir, u_int unmount_flags)
{
int error = 0;
#ifdef MNT2_GEN_OPT_DETACH
if (unmount_flags & AMU_UMOUNT_DETACH) {
error = umount2(mntdir, MNT2_GEN_OPT_DETACH);
if (error < 0 && (errno == EINVAL || errno == ENOENT))
error = 0; /* ignore EINVAL/ENOENT */
if (error < 0) { /* don't try FORCE if detach succeeded */
plog(XLOG_WARNING, "%s: unmount/detach: %m", mntdir);
/* fall through to try "force" (if flag specified) */
} else {
dlog("%s: unmount/detach: OK", mntdir);
return error;
}
}
#endif /* MNT2_GEN_OPT_DETACH */
#ifdef MNT2_GEN_OPT_FORCE
if (unmount_flags & AMU_UMOUNT_FORCE) {
plog(XLOG_INFO, "umount2_fs: trying unmount/forced on %s", mntdir);
error = umount2(mntdir, MNT2_GEN_OPT_FORCE);
if (error < 0 && (errno == EINVAL || errno == ENOENT))
error = 0; /* ignore EINVAL/ENOENT */
if (error < 0)
plog(XLOG_WARNING, "%s: unmount/force: %m", mntdir);
else
dlog("%s: unmount/force: OK", mntdir);
/* fall through to return whatever error we got (if any) */
}
#endif /* MNT2_GEN_OPT_FORCE */
return error;
}
#endif /* HAVE_UMOUNT2 && (MNT2_GEN_OPT_FORCE || MNT2_GEN_OPT_DETACH) */