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Date: Thu, 14 Mar 96 21:33:15 +0900
From: Mihoko Tanaka <m_tanaka@pa.yokogawa.co.jp>
Message-Id: <9603141233.AA20013@cabbage.pa.yokogawa.co.jp>
To: freebsd-hackers@freebsd.org
Subject: PANIC ( remove a file on the read-only FS)
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Hello all,

I'm using FreeBSD-2.1.0R on my PC.

When I removed a file which is on a read-only NFS by accident,
panic occured !

In kern/vfs_lookup.c:lookup() 
---------<extracts of kern/vfs_lookup.c:lookup()>---------------------
        /*  
         * We now have a segment name to search for, and a directory to search.
         */
unionlookup:
        ndp->ni_dvp = dp;
        error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
        if (error) {
#ifdef DIAGNOSTIC
                if (ndp->ni_vp != NULL) 
                        panic("leaf should be empty"); 
#endif  
---------<extracs of kern/vfs_lookup.c:lookup() :END>---------------------

The function 'VOP_LOOKUP()' calls xxx_lookup() (xxx : file system name).
When I remove a file which is on a read-only file system, 
VOP_LOOKUP() returns a error(EROFS) and ndp->ni_vp isn't NULL
because it exist.

So if I compile my kernel with 'DIAGNOSTIC', panic occurs .
If without 'DIAGNOSTIC', the system conflicts somewhere and gets into panic.


I made some patch for this trouble.
Is it correct?  Does anyone have another good idea?
-----------------(cut here)------------------------------------------
--- vfs_lookup.c	Wed Oct 25 18:17:15 1995
+++ vfs_lookup.c.new	Thu Mar 14 20:23:05 1996
@@ -399,6 +399,9 @@
 	error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
 	if (error) {
 #ifdef DIAGNOSTIC
+		if (error == EROFS)
+			goto bad;
+
 		if (ndp->ni_vp != NULL)
 			panic("leaf should be empty");
 #endif
@@ -422,7 +425,7 @@
 		 * If creating and at end of pathname, then can consider
 		 * allowing file to be created.
 		 */
-		if (rdonly) {
+		if (rdonly || (dp->v_mount->mnt_flag & MNT_RDONLY)) {
 			error = EROFS;
 			goto bad;
 		}
-----------------(cut here)------------------------------------------


--
Mihoko Tanaka 
<m_tanaka@pa.yokogawa.co.jp>