libshadowfs/common/shadow_control.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 (c) 2011, Oracle and/or its affiliates. All rights reserved.
 */

#include "shadow_impl.h"

/*
 * Removes an entire directory tree.  This should really be using openat() and
 * friends, but there is (annoyingly) no rmdirat().
 */
static void
shadow_remove_tree(const char *path)
{
    char child[PATH_MAX];
    struct stat64 statbuf;
    DIR *dir;
    struct dirent *dp;

    if (stat64(path, &statbuf) != 0)
        return;

    if (S_ISDIR(statbuf.st_mode)) {
        if ((dir = opendir(path)) != NULL) {
            while ((dp = readdir(dir)) != NULL) {
                if (strcmp(dp->d_name, ".") == 0 ||
                    strcmp(dp->d_name, "..") == 0)
                    continue;

                (void) snprintf(child, sizeof (child),
                    "%s/%s", path, dp->d_name);
                shadow_remove_tree(child);
            }
            (void) closedir(dir);
        }

        (void) rmdir(path);
    } else {
        (void) unlink(path);
    }
}

/*
 * Cancel any current shadow migration.  This involves clearing the shadow
 * mount option, clearing the ZFS shadow property if a ZFS dataset, and
 * removing the global extended attributes associated with the migration.
 */
int
shadow_cancel(shadow_handle_t *shp)
{
    libzfs_handle_t *zhdl;
    zfs_handle_t *zhp;
    char path[PATH_MAX];

    /*
     * Disable shadow migration.  If this is a ZFS dataset, then we clear
     * the corresponding ZFS property, which will tear down the underlying
     * mount.  If this is a regular filesystem, then we just do a remount
     * without the corresponding mount option.
     */
    if (shp->sh_dataset != NULL) {
        if ((zhdl = libzfs_init()) == NULL) {
            (void) shadow_error(ESHADOW_ZFS_NOENT,
                dgettext(TEXT_DOMAIN, "failed to load libzfs"));
            return (-1);
        }

        if ((zhp = zfs_open(zhdl, shp->sh_dataset,
            ZFS_TYPE_FILESYSTEM)) == NULL) {
            (void) shadow_zfs_error(zhdl);
            libzfs_fini(zhdl);
            return (-1);
        }

        if (zfs_prop_set(zhp, zfs_prop_to_name(ZFS_PROP_SHADOW),
            "none") != 0) {
            (void) shadow_zfs_error(zhdl);
            zfs_close(zhp);
            libzfs_fini(zhdl);
            return (-1);
        }

        zfs_close(zhp);
        libzfs_fini(zhdl);
    } else {
        if (mount(shp->sh_special, shp->sh_mountpoint, MS_REMOUNT,
            shp->sh_fstype, NULL, 0, NULL, 0) != 0) {
            return (shadow_error(ESHADOW_MNT_CLEAR,
                "failed to clear shadow mount option: %s",
                strerror(errno)));
        }
    }

    /*
     * Now that the shadow setting has been cleared, go through the private
     * .SUNWshadow directory and remove any internal data.  If this fails
     * for any reason, we ignore it and drive on, as there is no way to
     * resume the migration, and the filesystem data itself is intact.
     */
    (void) snprintf(path, sizeof (path), "%s/%s", shp->sh_mountpoint,
        VFS_SHADOW_PRIVATE_DIR);
    shadow_remove_tree(path);

    return (0);
}