From 093aa692861d0c91fd29979c13fc188760a3985b Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Tue, 15 Mar 2011 09:34:56 -0700 Subject: [PATCH] Always allow '-o remount,ro' Allow the mount(8) utility to always operate on all datasets when remounting them read-only. This critical for rc.sysinit/umountroot which remounts the root filesystem read-only during shutdown to ensure everything is correctly flushed to disk. Fix minor typo, the check to set zfsutil should use the bitwise '&'. I must have accidentally hit the adjacent '*' and obviously neither the compiler or my code review caught this. Fix it now. --- cmd/mount_zfs/mount_zfs.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/cmd/mount_zfs/mount_zfs.c b/cmd/mount_zfs/mount_zfs.c index fbb954acd220..52e5992d778e 100644 --- a/cmd/mount_zfs/mount_zfs.c +++ b/cmd/mount_zfs/mount_zfs.c @@ -298,7 +298,7 @@ main(int argc, char **argv) char mntopts[MNT_LINE_MAX] = { '\0' }; char badopt[MNT_LINE_MAX] = { '\0' }; char *dataset, *mntpoint; - unsigned long mntflags = 0, zfsflags = 0; + unsigned long mntflags = 0, zfsflags = 0, remount_ro = 0; int sloppy = 0, fake = 0, verbose = 0, nomtab = 0, zfsutil = 0; int error, c; @@ -402,7 +402,10 @@ main(int argc, char **argv) if (mntflags & MS_REMOUNT) nomtab = 1; - if (zfsflags * ZS_ZFSUTIL) + if ((mntflags & MS_REMOUNT) && (mntflags & MS_RDONLY)) + remount_ro = 1; + + if (zfsflags & ZS_ZFSUTIL) zfsutil = 1; if ((g_zfs = libzfs_init()) == NULL) @@ -427,6 +430,10 @@ main(int argc, char **argv) * 'zfs mount'. However, since 'zfs mount' actually invokes 'mount' * we differentiate the two cases using the 'zfsutil' mount option. * This mount option should only be supplied by the 'zfs mount' util. + * + * The only exception to the above rule is '-o remount,ro'. This is + * always allowed for non-legacy datasets for rc.sysinit/umountroot + * to safely remount the root filesystem and flush its cache. */ if (zfsutil && !strcmp(legacy, ZFS_MOUNTPOINT_LEGACY)) { (void) fprintf(stderr, gettext( @@ -437,7 +444,7 @@ main(int argc, char **argv) return (MOUNT_USAGE); } - if (!zfsutil && strcmp(legacy, ZFS_MOUNTPOINT_LEGACY)) { + if (!zfsutil && strcmp(legacy, ZFS_MOUNTPOINT_LEGACY) && !remount_ro) { (void) fprintf(stderr, gettext( "filesystem '%s' cannot be mounted using 'mount'.\n" "Use 'zfs set mountpoint=%s' or 'zfs mount %s'.\n"