Author: avg Date: Thu Jul 2 08:32:02 2015 New Revision: 285021 URL: https://svnweb.freebsd.org/changeset/base/285021
Log: zfs_mount(MS_REMOUNT): protect zfs_(un)register_callbacks calls We now take z_teardown_lock as a writer to ensure that there is no I/O while the filesystem state is in a flux. Also, zfs_suspend_fs() -> zfsvfs_teardown() call zfs_unregister_callbacks() and zfs_resume_fs() -> zfsvfs_setup() call zfs_unregister_callbacks(). Previously there was no synchronization between those calls and the calls in the re-mounting case. That could lead to concurrent execution and a crash. PR: 180060 Differential Revision: https://reviews.freebsd.org/D2865 Suggested by: mahrens Reviewed by: delphij, pho, mahrens, will MFC after: 13 days Sponsored by: ClusterHQ Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c Thu Jul 2 08:25:45 2015 (r285020) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c Thu Jul 2 08:32:02 2015 (r285021) @@ -1717,9 +1717,19 @@ zfs_mount(vfs_t *vfsp) * according to those options set in the current VFS options. */ if (vfsp->vfs_flag & MS_REMOUNT) { - /* refresh mount options */ - zfs_unregister_callbacks(vfsp->vfs_data); + zfsvfs_t *zfsvfs = vfsp->vfs_data; + + /* + * Refresh mount options with z_teardown_lock blocking I/O while + * the filesystem is in an inconsistent state. + * The lock also serializes this code with filesystem + * manipulations between entry to zfs_suspend_fs() and return + * from zfs_resume_fs(). + */ + rrm_enter(&zfsvfs->z_teardown_lock, RW_WRITER, FTAG); + zfs_unregister_callbacks(zfsvfs); error = zfs_register_callbacks(vfsp); + rrm_exit(&zfsvfs->z_teardown_lock, FTAG); goto out; } _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
