libzfs_mount.c revision 99653d4ee642c6528e88224f12409a5f23060994
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260921a4509dd7666c6613f413be409b66181642eschrock * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Use is subject to license terms.
fa9e4066f08beec538e775443c5be79dd423fcabahrens#pragma ident "%Z%%M% %I% %E% SMI"
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Routines to manage ZFS mounts. We separate all the nasty routines that have
fa9e4066f08beec538e775443c5be79dd423fcabahrens * to deal with the OS. The main entry points are:
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_is_mounted()
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_mount()
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_unmount()
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_unmountall()
fa9e4066f08beec538e775443c5be79dd423fcabahrens * These functions are used by mount and unmount, and when changing a
fa9e4066f08beec538e775443c5be79dd423fcabahrens * filesystem's mountpoint. This file also contains the functions used to
fa9e4066f08beec538e775443c5be79dd423fcabahrens * manage sharing filesystems via NFS:
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_is_shared()
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_share()
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_unshare()
fa9e4066f08beec538e775443c5be79dd423fcabahrens * zfs_unshareall()
99653d4ee642c6528e88224f12409a5f23060994eschrock * Search the sharetab for the given mountpoint, returning true if it is found.
99653d4ee642c6528e88224f12409a5f23060994eschrockis_shared(libzfs_handle_t *hdl, const char *mountpoint)
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
99653d4ee642c6528e88224f12409a5f23060994eschrock while (fgets(buf, sizeof (buf), hdl->libzfs_sharetab) != NULL) {
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* the mountpoint is the first entry on each line */
99653d4ee642c6528e88224f12409a5f23060994eschrock * Returns true if the specified directory is empty. If we can't open the
99653d4ee642c6528e88224f12409a5f23060994eschrock * directory at all, return true so that the mount can fail with a more
fa9e4066f08beec538e775443c5be79dd423fcabahrens * informative error message.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Checks to see if the mount is active. If the filesystem is mounted, we fill
fa9e4066f08beec538e775443c5be79dd423fcabahrens * in 'where' with the current mountpoint, and return 1. Otherwise, we return
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Search for the entry in /etc/mnttab. We don't bother getting the
fa9e4066f08beec538e775443c5be79dd423fcabahrens * mountpoint, as we can just search for the special device. This will
fa9e4066f08beec538e775443c5be79dd423fcabahrens * also let us find mounts when the mountpoint is 'legacy'.
99653d4ee642c6528e88224f12409a5f23060994eschrock if (getmntany(zhp->zfs_hdl->libzfs_mnttab, &entry, &search) != 0)
99653d4ee642c6528e88224f12409a5f23060994eschrock *where = zfs_strdup(zhp->zfs_hdl, entry.mnt_mountp);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Mount the given filesystem.
fa9e4066f08beec538e775443c5be79dd423fcabahrenszfs_mount(zfs_handle_t *zhp, const char *options, int flags)
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* ignore non-filesystems */
fa9e4066f08beec538e775443c5be79dd423fcabahrens if (zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, mountpoint,
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* return success if there is no mountpoint set */
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * If the 'zoned' property is set, and we're in the global zone, simply
fa9e4066f08beec538e775443c5be79dd423fcabahrens * return success.
99653d4ee642c6528e88224f12409a5f23060994eschrock return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* Create the directory if it doesn't already exist */
99653d4ee642c6528e88224f12409a5f23060994eschrock "failed to create mountpoint"));
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Determine if the mountpoint is empty. If so, refuse to perform the
fa9e4066f08beec538e775443c5be79dd423fcabahrens * mount. We don't perform this check if MS_OVERLAY is specified, which
fa9e4066f08beec538e775443c5be79dd423fcabahrens * would defeat the point. We also avoid this check if 'remount' is
fa9e4066f08beec538e775443c5be79dd423fcabahrens * specified.
99653d4ee642c6528e88224f12409a5f23060994eschrock "directory is not empty"));
99653d4ee642c6528e88224f12409a5f23060994eschrock dgettext(TEXT_DOMAIN, "cannot mount '%s'"), mountpoint));
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* perform the mount */
fa9e4066f08beec538e775443c5be79dd423fcabahrens if (mount(zfs_get_name(zhp), mountpoint, MS_OPTIONSTR | flags,
fa9e4066f08beec538e775443c5be79dd423fcabahrens MNTTYPE_ZFS, NULL, 0, mntopts, sizeof (mntopts)) != 0) {
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Generic errors are nasty, but there are just way too many
fa9e4066f08beec538e775443c5be79dd423fcabahrens * from mount(), and they're well-understood. We pick a few
fa9e4066f08beec538e775443c5be79dd423fcabahrens * common ones to improve upon.
99653d4ee642c6528e88224f12409a5f23060994eschrock "mountpoint or dataset is busy"));
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Unmount the given filesystem.
fa9e4066f08beec538e775443c5be79dd423fcabahrenszfs_unmount(zfs_handle_t *zhp, const char *mountpoint, int flags)
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* check to see if need to unmount the filesystem */
fa9e4066f08beec538e775443c5be79dd423fcabahrens if (mountpoint != NULL || ((zfs_get_type(zhp) == ZFS_TYPE_FILESYSTEM) &&
99653d4ee642c6528e88224f12409a5f23060994eschrock getmntany(zhp->zfs_hdl->libzfs_mnttab, &entry, &search) == 0)) {
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Always unshare the filesystem first.
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (-1);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Try to unmount the filesystem. There is no reason to try a
fa9e4066f08beec538e775443c5be79dd423fcabahrens * forced unmount because the vnodes will still carry a
fa9e4066f08beec538e775443c5be79dd423fcabahrens * reference to the underlying dataset, so we can't destroy it
fa9e4066f08beec538e775443c5be79dd423fcabahrens * In the unmount case, we print out a slightly more informative
fa9e4066f08beec538e775443c5be79dd423fcabahrens * error message, though we'll be relying on the poor error
fa9e4066f08beec538e775443c5be79dd423fcabahrens * semantics from the kernel.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Don't actually destroy the underlying directory
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Unmount this filesystem and any children inheriting the mountpoint property.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * To do this, just act like we're changing the mountpoint property, but don't
fa9e4066f08beec538e775443c5be79dd423fcabahrens * remount the filesystems afterwards.
fa9e4066f08beec538e775443c5be79dd423fcabahrens clp = changelist_gather(zhp, ZFS_PROP_MOUNTPOINT, flags);
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (-1);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Check to see if the filesystem is currently shared.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Share the given filesystem according to the options in 'sharenfs'. We rely
fa9e4066f08beec538e775443c5be79dd423fcabahrens * on share(1M) to the dirty work for us.
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* ignore non-filesystems */
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* return success if there is no mountpoint set */
99653d4ee642c6528e88224f12409a5f23060994eschrock mountpoint, sizeof (mountpoint), NULL, NULL, 0, B_FALSE) != 0 ||
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* return success if there are no share options */
fa9e4066f08beec538e775443c5be79dd423fcabahrens if (zfs_prop_get(zhp, ZFS_PROP_SHARENFS, shareopts, sizeof (shareopts),
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * If the 'zoned' property is set, simply return success since:
fa9e4066f08beec538e775443c5be79dd423fcabahrens * 1. in a global zone, a dataset should not be shared if it's
fa9e4066f08beec538e775443c5be79dd423fcabahrens * managed in a local zone.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * 2. in a local zone, NFS server is not available.
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Invoke the share(1M) command. We always do this, even if it's
fa9e4066f08beec538e775443c5be79dd423fcabahrens * currently shared, as the options may have changed.
fa9e4066f08beec538e775443c5be79dd423fcabahrens (void) snprintf(buf, sizeof (buf), "/usr/sbin/share "
fa9e4066f08beec538e775443c5be79dd423fcabahrens (void) snprintf(buf, sizeof (buf), "/usr/sbin/share "
fa9e4066f08beec538e775443c5be79dd423fcabahrens * share(1M) should only produce output if there is some kind
fa9e4066f08beec538e775443c5be79dd423fcabahrens * of error. All output begins with "share_nfs: ", so we trim
fa9e4066f08beec538e775443c5be79dd423fcabahrens * this off to get to the real error.
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (-1);
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Unshare the given filesystem.
fa9e4066f08beec538e775443c5be79dd423fcabahrenszfs_unshare(zfs_handle_t *zhp, const char *mountpoint)
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* check to see if need to unmount the filesystem */
fa9e4066f08beec538e775443c5be79dd423fcabahrens if (mountpoint != NULL || ((zfs_get_type(zhp) == ZFS_TYPE_FILESYSTEM) &&
99653d4ee642c6528e88224f12409a5f23060994eschrock getmntany(zhp->zfs_hdl->libzfs_mnttab, &entry, &search) == 0)) {
fa9e4066f08beec538e775443c5be79dd423fcabahrens "/usr/sbin/unshare \"%s\" 2>&1",
fa9e4066f08beec538e775443c5be79dd423fcabahrens * unshare(1M) should only produce output if there is
fa9e4066f08beec538e775443c5be79dd423fcabahrens * some kind of error. All output begins with "unshare
fa9e4066f08beec538e775443c5be79dd423fcabahrens * nfs: ", so we trim this off to get to the real error.
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (0);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Same as zfs_unmountall(), but for unshares.
fa9e4066f08beec538e775443c5be79dd423fcabahrens return (-1);
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Remove the mountpoint associated with the current dataset, if necessary.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * We only remove the underlying directory if:
fa9e4066f08beec538e775443c5be79dd423fcabahrens * - The mountpoint is not 'none' or 'legacy'
fa9e4066f08beec538e775443c5be79dd423fcabahrens * - The mountpoint is non-empty
fa9e4066f08beec538e775443c5be79dd423fcabahrens * - The mountpoint is the default or inherited
fa9e4066f08beec538e775443c5be79dd423fcabahrens * - The 'zoned' property is set, or we're in a local zone
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Any other directories we leave alone.
fa9e4066f08beec538e775443c5be79dd423fcabahrens /* ignore non-filesystems */
fa9e4066f08beec538e775443c5be79dd423fcabahrens if (zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, mountpoint,
fa9e4066f08beec538e775443c5be79dd423fcabahrens sizeof (mountpoint), &sourcetype, source, sizeof (source),
fa9e4066f08beec538e775443c5be79dd423fcabahrens * Try to remove the directory, silently ignoring any errors.
fa9e4066f08beec538e775443c5be79dd423fcabahrens * The filesystem may have since been removed or moved around,
fa9e4066f08beec538e775443c5be79dd423fcabahrens * and this isn't really useful to the administrator in any