[OpenAFS] cm fails to invalidate cache for deleted files in volume root w/ fakestat

[Rainer Toebbicke]

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We ran into this over a year ago and fixed it, but I must have 
forgotten to submit the fix.

It is actually the detection of a "cell" in the mount point string 
which triggers the (loosely consistent) fakestat handling - it's 
treated like a foreign cell and the mount point is never "completely 
evaluated", i.e.  logically replaced by the root directory of the 
volume in question. As a result, callbacks are ignored, as they go 
against the directory and not the mount point.

The attached patch takes care of that.

(Bcc'ed openafs-bugs)


Stephan Wiesand schrieb:
> If a client runs with the -fakestat[-all] option, and has a file cached 
> that resides in the root directory of a volume affected by fakestat, it 
> fails to invalidate its cache for this file when it's deleted:
> 
> ClientA: touch x
> ClientB: ls -l x
> ... 0 Apr 10 13:10 x
> 
> ClientA: echo a >> x
> ClientB: ls -l x; cat x
> ... 2 Apr 10 13:11 x
> a
> 
> ClientA: rm x
> ClientB: ls -l x; cat x
> ... 2 Apr 10 13:11 x                   (!)
> a                                      (!)
> 
> ClientA: echo b > x
> ClientB: ls -l x; cat x
> ... 2 Apr 10 13:11 x                   (!)
> a                                      (!)
> 
> ClientB: fs flushv; ls -l x; cat x
> ... 2 Apr 10 13:12 x
> b
> 
> 
> I guess it's the same issue reported by Jack Neely on March 17th. We're 
> not running with -fakestat-all, just -fakestat. The problem struck when 
> mount points for local volumes were accidentally created with the -cell 
> option. We can reproduce the problem with local and foreign volumes. 
> Turning off fakestat eliminates it reliably.
> 
> We observe this with various Linux clients. OpenAFS 1.4.6 or 1.4.7pre3, 
> SL3/4/5, 32/64-bit.
> 
> An SL3 client still running 1.2.13 does not exhibit this problem.
> 
> Bcc to openafs-bugs.
> 


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Rainer Toebbicke
European Laboratory for Particle Physics(CERN) - Geneva, Switzerland
Phone: +41 22 767 8985       Fax: +41 22 767 7155

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--- openafs/src/afs/LINUX/osi_vnodeops.c	2006-05-09 16:30:58.000000000 +0200
+++ openafs/src/afs/LINUX/osi_vnodeops.c	2007-02-02 15:26:01.000000000 +0100
@@ -894,9 +894,16 @@
 	vcp = VTOAFS(dp->d_inode);
 	pvcp = VTOAFS(dp->d_parent->d_inode);		/* dget_parent()? */
 
+
 	if (vcp == afs_globalVp)
 	    goto good_dentry;
 
+	if (vcp->mvstat == 1) {		/* mount point */
+	    if (vcp->mvid && (vcp->states & CMValid)) {
+		/* a mount point, not yet replaced by its directory */
+		goto bad_dentry;
+	    }
+	} else
 	if (*dp->d_name.name != '/' && vcp->mvstat == 2)	/* root vnode */
 	    check_bad_parent(dp);	/* check and correct mvid */
 
--- openafs/src/afs/VNOPS/afs_vnop_lookup.c	2006-02-18 05:09:36.000000000 +0100
+++ openafs/src/afs/VNOPS/afs_vnop_lookup.c	2007-02-02 15:04:22.000000000 +0100
@@ -1120,6 +1120,7 @@
     register afs_int32 code;
     register afs_int32 bulkcode = 0;
     int pass = 0, hit = 0;
+    int force_eval = afs_fakestat_enable ? 0 : 1;
     long dirCookie;
     extern afs_int32 afs_mariner;	/*Writing activity to log? */
     afs_hyper_t versionNo;
@@ -1437,7 +1438,6 @@
     }				/* sub-block just to reduce stack usage */
 
     if (tvc) {
-	int force_eval = afs_fakestat_enable ? 0 : 1;
 
 	if (adp->states & CForeign)
 	    tvc->states |= CForeign;
@@ -1459,6 +1459,8 @@
 		force_eval = 1;
 	    ReleaseReadLock(&tvc->lock);
 	}
+	if (tvc->mvstat == 1 && (tvc->states & CMValid) && tvc->mvid != NULL)
+	    force_eval = 1;		/* This is now almost for free, get it correct */
 #if defined(UKERNEL) && defined(AFS_WEB_ENHANCEMENTS)
 	if (!(flags & AFS_LOOKUP_NOEVAL))
 	    /* don't eval mount points */
@@ -1584,7 +1586,7 @@
 	     * rather than the vc of the mount point itself.  we can still find the
 	     * mount point's vc in the vcache by its fid. */
 #endif /* UKERNEL && AFS_WEB_ENHANCEMENTS */
-	    if (!hit) {
+	    if (!hit && force_eval) {
 		osi_dnlc_enter(adp, aname, tvc, &versionNo);
 	    } else {
 #ifdef AFS_LINUX20_ENV

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