libzfs_mount.c revision 260921a4509dd7666c6613f413be409b66181642
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* Routines to manage ZFS mounts. We separate all the nasty routines that have
* to deal with the OS. The main entry points are:
*
* zfs_is_mounted()
* zfs_mount()
* zfs_unmount()
* zfs_unmountall()
*
* These functions are used by mount and unmount, and when changing a
* filesystem's mountpoint. This file also contains the functions used to
* manage sharing filesystems via NFS:
*
* zfs_is_shared()
* zfs_share()
* zfs_unshare()
* zfs_unshareall()
*/
#include <dirent.h>
#include <errno.h>
#include <libgen.h>
#include <libintl.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <zone.h>
#include <sys/mntent.h>
#include <sys/mnttab.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <libzfs.h>
#include "libzfs_impl.h"
/*
* The following two files are opened as part of zfs_init(). It's OK to for
* the sharetab to be NULL, but mnttab must always be non-NULL;
*/
FILE *mnttab_file;
FILE *sharetab_file;
/*
* Search the sharetab for the given mountpoint, returning TRUE if it is found.
*/
static int
is_shared(const char *mountpoint)
{
char buf[MAXPATHLEN], *tab;
if (sharetab_file == NULL)
return (0);
(void) fseek(sharetab_file, 0, SEEK_SET);
while (fgets(buf, sizeof (buf), sharetab_file) != NULL) {
/* the mountpoint is the first entry on each line */
if ((tab = strchr(buf, '\t')) != NULL) {
*tab = '\0';
if (strcmp(buf, mountpoint) == 0)
return (1);
}
}
return (0);
}
/*
* Returns TRUE if the specified directory is empty. If we can't open the
* directory at all, return TRUE so that the mount can fail with a more
* informative error message.
*/
static int
dir_is_empty(const char *dirname)
{
DIR *dirp;
struct dirent64 *dp;
if ((dirp = opendir(dirname)) == NULL)
return (TRUE);
while ((dp = readdir64(dirp)) != NULL) {
if (strcmp(dp->d_name, ".") == 0 ||
strcmp(dp->d_name, "..") == 0)
continue;
(void) closedir(dirp);
return (FALSE);
}
(void) closedir(dirp);
return (TRUE);
}
/*
* Checks to see if the mount is active. If the filesystem is mounted, we fill
* in 'where' with the current mountpoint, and return 1. Otherwise, we return
* 0.
*/
int
zfs_is_mounted(zfs_handle_t *zhp, char **where)
{
struct mnttab search = { 0 }, entry;
/*
* Search for the entry in /etc/mnttab. We don't bother getting the
* mountpoint, as we can just search for the special device. This will
* also let us find mounts when the mountpoint is 'legacy'.
*/
search.mnt_special = (char *)zfs_get_name(zhp);
rewind(mnttab_file);
if (getmntany(mnttab_file, &entry, &search) != 0)
return (FALSE);
if (where != NULL)
*where = zfs_strdup(entry.mnt_mountp);
return (TRUE);
}
/*
* Mount the given filesystem.
*/
int
zfs_mount(zfs_handle_t *zhp, const char *options, int flags)
{
struct stat buf;
char mountpoint[ZFS_MAXPROPLEN];
char mntopts[MNT_LINE_MAX];
if (options == NULL)
mntopts[0] = '\0';
else
(void) strlcpy(mntopts, options, sizeof (mntopts));
/* ignore non-filesystems */
if (zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, mountpoint,
sizeof (mountpoint), NULL, NULL, 0, FALSE) != 0)
return (0);
/* return success if there is no mountpoint set */
if (strcmp(mountpoint, ZFS_MOUNTPOINT_NONE) == 0 ||
strcmp(mountpoint, ZFS_MOUNTPOINT_LEGACY) == 0)
return (0);
/*
* If the 'zoned' property is set, and we're in the global zone, simply
* return success.
*/
if (zfs_prop_get_int(zhp, ZFS_PROP_ZONED)) {
char zonename[ZONENAME_MAX];
if (getzonenamebyid(getzoneid(), zonename,
sizeof (zonename)) < 0) {
zfs_error(dgettext(TEXT_DOMAIN, "internal error: "
"cannot determine current zone"));
return (1);
}
if (strcmp(zonename, "global") == 0)
return (0);
}
/* Create the directory if it doesn't already exist */
if (lstat(mountpoint, &buf) != 0) {
if (mkdirp(mountpoint, 0755) != 0) {
zfs_error(dgettext(TEXT_DOMAIN, "cannot mount '%s': "
"unable to create mountpoint"), mountpoint);
return (1);
}
}
/*
* Determine if the mountpoint is empty. If so, refuse to perform the
* mount. We don't perform this check if MS_OVERLAY is specified, which
* would defeat the point. We also avoid this check if 'remount' is
* specified.
*/
if ((flags & MS_OVERLAY) == 0 &&
strstr(mntopts, MNTOPT_REMOUNT) == NULL &&
!dir_is_empty(mountpoint)) {
zfs_error(dgettext(TEXT_DOMAIN, "cannot mount '%s': "
"directory is not empty"), mountpoint);
zfs_error(dgettext(TEXT_DOMAIN, "use legacy mountpoint to "
"allow this behavior, or use the -O flag"));
return (1);
}
/* perform the mount */
if (mount(zfs_get_name(zhp), mountpoint, MS_OPTIONSTR | flags,
MNTTYPE_ZFS, NULL, 0, mntopts, sizeof (mntopts)) != 0) {
/*
* Generic errors are nasty, but there are just way too many
* from mount(), and they're well-understood. We pick a few
* common ones to improve upon.
*/
switch (errno) {
case EBUSY:
zfs_error(dgettext(TEXT_DOMAIN, "cannot mount '%s': "
"mountpoint or dataset is busy"), zhp->zfs_name);
break;
case EPERM:
case EACCES:
zfs_error(dgettext(TEXT_DOMAIN, "cannot mount '%s': "
"permission denied"), zhp->zfs_name,
mountpoint);
break;
default:
zfs_error(dgettext(TEXT_DOMAIN,
"cannot mount '%s': %s"),
mountpoint, strerror(errno));
break;
}
return (1);
}
return (0);
}
/*
* Unmount the given filesystem.
*/
int
zfs_unmount(zfs_handle_t *zhp, const char *mountpoint, int flags)
{
struct mnttab search = { 0 }, entry;
/* check to see if need to unmount the filesystem */
search.mnt_special = (char *)zfs_get_name(zhp);
rewind(mnttab_file);
if (mountpoint != NULL || ((zfs_get_type(zhp) == ZFS_TYPE_FILESYSTEM) &&
getmntany(mnttab_file, &entry, &search) == 0)) {
if (mountpoint == NULL)
mountpoint = entry.mnt_mountp;
/*
* Always unshare the filesystem first.
*/
if (zfs_unshare(zhp, mountpoint) != 0)
return (-1);
/*
* Try to unmount the filesystem. There is no reason to try a
* forced unmount because the vnodes will still carry a
* reference to the underlying dataset, so we can't destroy it
* anyway.
*
* In the unmount case, we print out a slightly more informative
* error message, though we'll be relying on the poor error
* semantics from the kernel.
*/
if (umount2(mountpoint, flags) != 0) {
zfs_error(dgettext(TEXT_DOMAIN,
"cannot unmount '%s': %s"),
mountpoint, strerror(errno));
return (-1);
}
/*
* Don't actually destroy the underlying directory
*/
}
return (0);
}
/*
* Unmount this filesystem and any children inheriting the mountpoint property.
* To do this, just act like we're changing the mountpoint property, but don't
* remount the filesystems afterwards.
*/
int
zfs_unmountall(zfs_handle_t *zhp, int flags)
{
prop_changelist_t *clp;
int ret;
clp = changelist_gather(zhp, ZFS_PROP_MOUNTPOINT, flags);
if (clp == NULL)
return (-1);
ret = changelist_prefix(clp);
changelist_free(clp);
return (ret);
}
/*
* Check to see if the filesystem is currently shared.
*/
int
zfs_is_shared(zfs_handle_t *zhp, char **where)
{
char *mountpoint;
if (!zfs_is_mounted(zhp, &mountpoint))
return (FALSE);
if (is_shared(mountpoint)) {
if (where != NULL)
*where = mountpoint;
else
free(mountpoint);
return (TRUE);
} else {
free(mountpoint);
return (FALSE);
}
}
/*
* Share the given filesystem according to the options in 'sharenfs'. We rely
* on share(1M) to the dirty work for us.
*/
int
zfs_share(zfs_handle_t *zhp)
{
char mountpoint[ZFS_MAXPROPLEN];
char shareopts[ZFS_MAXPROPLEN];
char buf[MAXPATHLEN];
FILE *fp;
/* ignore non-filesystems */
if (zfs_get_type(zhp) != ZFS_TYPE_FILESYSTEM)
return (0);
/* return success if there is no mountpoint set */
if (zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT,
mountpoint, sizeof (mountpoint), NULL, NULL, 0, FALSE) != 0 ||
strcmp(mountpoint, ZFS_MOUNTPOINT_NONE) == 0 ||
strcmp(mountpoint, ZFS_MOUNTPOINT_LEGACY) == 0)
return (0);
/* return success if there are no share options */
if (zfs_prop_get(zhp, ZFS_PROP_SHARENFS, shareopts, sizeof (shareopts),
NULL, NULL, 0, FALSE) != 0 ||
strcmp(shareopts, "off") == 0)
return (0);
/*
* If the 'zoned' property is set, simply return success since:
* 1. in a global zone, a dataset should not be shared if it's
* managed in a local zone.
* 2. in a local zone, NFS server is not available.
*/
if (zfs_prop_get_int(zhp, ZFS_PROP_ZONED)) {
return (0);
}
/*
* Invoke the share(1M) command. We always do this, even if it's
* currently shared, as the options may have changed.
*/
if (strcmp(shareopts, "on") == 0)
(void) snprintf(buf, sizeof (buf), "/usr/sbin/share "
"-F nfs \"%s\" 2>&1", mountpoint);
else
(void) snprintf(buf, sizeof (buf), "/usr/sbin/share "
"-F nfs -o \"%s\" \"%s\" 2>&1", shareopts,
mountpoint);
if ((fp = popen(buf, "r")) == NULL) {
zfs_error(dgettext(TEXT_DOMAIN, "cannot share '%s': "
"share(1M) failed"), zfs_get_name(zhp));
return (-1);
}
/*
* share(1M) should only produce output if there is some kind
* of error. All output begins with "share_nfs: ", so we trim
* this off to get to the real error.
*/
if (fgets(buf, sizeof (buf), fp) != NULL) {
char *colon = strchr(buf, ':');
while (buf[strlen(buf) - 1] == '\n')
buf[strlen(buf) - 1] = '\0';
if (colon == NULL)
zfs_error(dgettext(TEXT_DOMAIN, "cannot share "
"'%s': share(1M) failed"),
zfs_get_name(zhp));
else
zfs_error(dgettext(TEXT_DOMAIN, "cannot share "
"'%s': %s"), zfs_get_name(zhp),
colon + 2);
verify(pclose(fp) != 0);
return (-1);
}
verify(pclose(fp) == 0);
return (0);
}
/*
* Unshare the given filesystem.
*/
int
zfs_unshare(zfs_handle_t *zhp, const char *mountpoint)
{
char buf[MAXPATHLEN];
struct mnttab search = { 0 }, entry;
/* check to see if need to unmount the filesystem */
search.mnt_special = (char *)zfs_get_name(zhp);
rewind(mnttab_file);
if (mountpoint != NULL || ((zfs_get_type(zhp) == ZFS_TYPE_FILESYSTEM) &&
getmntany(mnttab_file, &entry, &search) == 0)) {
if (mountpoint == NULL)
mountpoint = entry.mnt_mountp;
if (is_shared(mountpoint)) {
FILE *fp;
(void) snprintf(buf, sizeof (buf),
"/usr/sbin/unshare \"%s\" 2>&1",
mountpoint);
if ((fp = popen(buf, "r")) == NULL) {
zfs_error(dgettext(TEXT_DOMAIN, "cannot "
"unshare '%s': unshare(1M) failed"),
zfs_get_name(zhp));
return (-1);
}
/*
* unshare(1M) should only produce output if there is
* some kind of error. All output begins with "unshare
* nfs: ", so we trim this off to get to the real error.
*/
if (fgets(buf, sizeof (buf), fp) != NULL) {
char *colon = strchr(buf, ':');
while (buf[strlen(buf) - 1] == '\n')
buf[strlen(buf) - 1] = '\0';
if (colon == NULL)
zfs_error(dgettext(TEXT_DOMAIN,
"cannot unshare '%s': unshare(1M) "
"failed"), zfs_get_name(zhp));
else
zfs_error(dgettext(TEXT_DOMAIN,
"cannot unshare '%s': %s"),
zfs_get_name(zhp), colon + 2);
verify(pclose(fp) != 0);
return (-1);
}
verify(pclose(fp) == 0);
}
}
return (0);
}
/*
* Same as zfs_unmountall(), but for unshares.
*/
int
zfs_unshareall(zfs_handle_t *zhp)
{
prop_changelist_t *clp;
int ret;
clp = changelist_gather(zhp, ZFS_PROP_SHARENFS, 0);
if (clp == NULL)
return (-1);
ret = changelist_unshare(clp);
changelist_free(clp);
return (ret);
}
/*
* Remove the mountpoint associated with the current dataset, if necessary.
* We only remove the underlying directory if:
*
* - The mountpoint is not 'none' or 'legacy'
* - The mountpoint is non-empty
* - The mountpoint is the default or inherited
* - The 'zoned' property is set, or we're in a local zone
*
* Any other directories we leave alone.
*/
void
remove_mountpoint(zfs_handle_t *zhp)
{
char mountpoint[ZFS_MAXPROPLEN];
char source[ZFS_MAXNAMELEN];
zfs_source_t sourcetype;
char zonename[ZONENAME_MAX];
/* ignore non-filesystems */
if (zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, mountpoint,
sizeof (mountpoint), &sourcetype, source, sizeof (source),
FALSE) != 0)
return;
if (getzonenamebyid(getzoneid(), zonename, sizeof (zonename)) < 0)
zfs_fatal(dgettext(TEXT_DOMAIN, "internal error: "
"cannot determine current zone"));
if (strcmp(mountpoint, ZFS_MOUNTPOINT_NONE) != 0 &&
strcmp(mountpoint, ZFS_MOUNTPOINT_LEGACY) != 0 &&
(sourcetype == ZFS_SRC_DEFAULT ||
sourcetype == ZFS_SRC_INHERITED) &&
(!zfs_prop_get_int(zhp, ZFS_PROP_ZONED) ||
strcmp(zonename, "global") != 0)) {
/*
* Try to remove the directory, silently ignoring any errors.
* The filesystem may have since been removed or moved around,
* and this isn't really useful to the administrator in any
* way.
*/
(void) rmdir(mountpoint);
}
}