Function suspend_all_fs

freebsd/kern/vfs_mount.c:2554–2586

* Suspend write operations on all local writeable filesystems. Does * full sync of them in the process. * * Iterate over the mount points in reverse order, suspending most * recently mounted filesystems first. It handles a case where a * filesystem mounted from a md(4) vnode-backed device should be * suspended before the filesystem that owns the vnode. */

 * suspended before the filesystem that owns the vnode.
 */
void
suspend_all_fs(void)
{
	struct mount *mp;
	int error;

	mtx_lock(&mountlist_mtx);
	TAILQ_FOREACH_REVERSE(mp, &mountlist, mntlist, mnt_list) {
		error = vfs_busy(mp, MBF_MNTLSTLOCK | MBF_NOWAIT);
		if (error != 0)
			continue;
		if ((mp->mnt_flag & (MNT_RDONLY | MNT_LOCAL)) != MNT_LOCAL ||
		    (mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
			mtx_lock(&mountlist_mtx);
			vfs_unbusy(mp);
			continue;
		}
		error = vfs_write_suspend(mp, 0);
		if (error == 0) {
			MNT_ILOCK(mp);
			MPASS((mp->mnt_kern_flag & MNTK_SUSPEND_ALL) == 0);
			mp->mnt_kern_flag |= MNTK_SUSPEND_ALL;
			MNT_IUNLOCK(mp);
			mtx_lock(&mountlist_mtx);
		} else {
			printf("suspend of %s failed, error %d\n",
			    mp->mnt_stat.f_mntonname, error);
			mtx_lock(&mountlist_mtx);
			vfs_unbusy(mp);
		}
	}
	mtx_unlock(&mountlist_mtx);
}

void
resume_all_fs(void)