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Date:      Thu, 11 May 2000 20:15:51 GMT
From:      mellon@pobox.com
To:        FreeBSD-gnats-submit@freebsd.org
Subject:   kern/18505: missing VFS_START call.
Message-ID:  <200005112015.UAA00265@happy.checkpoint.com>

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>Number:         18505
>Category:       kern
>Synopsis:       missing VFS_START call.
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu May 11 10:20:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Anatoly Vorobey
>Release:        FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:

5.0-CURRENT

>Description:

VFS_START is not called after VFS_MOUNT in vfs_mountroot_try (vfs_conf.c).
This is contrary to VFS_START's intention and documentation. The deed
only goes unpunished because no filesystem currently does anything on
VFS_START except MFS, but it's only a matter of time before some might
try something. MFS grabs the calling process and turns it into a workhorse
on VFS_START, but MFS won't mount as root so it's okay (and correct) 
to call VFS_START there.

>How-To-Repeat:

>Fix:

Two choices:
1) Document VFS_START as a dirty hack made especially for MFS which no
other filesystems should ever use or rely on;
2) (preferrable IMHO) apply the patch below. It also fixes a typo in
the comment for MFS code which stops it from mounting as root.

Index: vfs_conf.c
===================================================================
RCS file: /freebsd/cvs/src/sys/kern/vfs_conf.c,v
retrieving revision 1.50
diff -u -r1.50 vfs_conf.c
--- vfs_conf.c	2000/03/20 16:28:26	1.50
+++ vfs_conf.c	2000/05/11 20:03:06
@@ -235,6 +235,13 @@
 		/* sanity check system clock against root filesystem timestamp */
 		inittodr(mp->mnt_time);
 		vfs_unbusy(mp, curproc);
+
+		/* 
+		 * MFS grabs the process when it calls VFS_START and doesn't
+		 * let it go, but MFS won't allow itself to be mounted as root.
+		 */
+
+		error = VFS_START(mp, 0, curproc);
 	}
 	return(error);
 }
Index: mfs_vfsops.c
===================================================================
RCS file: /freebsd/cvs/src/sys/ufs/mfs/mfs_vfsops.c,v
retrieving revision 1.84
diff -u -r1.84 mfs_vfsops.c
--- mfs_vfsops.c	2000/05/05 09:59:06	1.84
+++ mfs_vfsops.c	2000/05/11 20:03:57
@@ -182,7 +182,7 @@
 		 ***
 		 */
 
-		/* you loose */
+		/* you lose */
 		panic("mfs_mount: mount MFS as root: not configured!");
 	}
 



>Release-Note:
>Audit-Trail:
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