LINUX: Avoid d_revalidate failure on mtpt mismatch

[openafs.git] / src / afs / LINUX / osi_vnodeops.c

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index e03187f..b2ab9d5 100644 (file)
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -1291,9 +1291,36 @@ afs_linux_dentry_revalidate(struct dentry *dp, int flags)
        if (locked && (parent_dv > dp->d_time || !(vcp->f.states & CStatd))) {
            struct vattr *vattr = NULL;
            int code;
+           int lookup_good;
 
            code = afs_lookup(pvcp, (char *)dp->d_name.name, &tvc, credp);
-           if (code || tvc != vcp) {
+
+           if (code) {
+               /* We couldn't perform the lookup, so we're not okay. */
+               lookup_good = 0;
+
+           } else if (tvc == vcp) {
+               /* We got back the same vcache, so we're good. */
+               lookup_good = 1;
+
+           } else if (tvc == VTOAFS(dp->d_inode)) {
+               /* We got back the same vcache, so we're good. This is
+                * different from the above case, because sometimes 'vcp' is
+                * not the same as the vcache for dp->d_inode, if 'vcp' was a
+                * mtpt and we evaluated it to a root dir. In rare cases,
+                * afs_lookup might not evalute the mtpt when we do, or vice
+                * versa, so the previous case will not succeed. But this is
+                * still 'correct', so make sure not to mark the dentry as
+                * invalid; it still points to the same thing! */
+               lookup_good = 1;
+
+           } else {
+               /* We got back a different file, so we're definitely not
+                * okay. */
+               lookup_good = 0;
+           }
+
+           if (!lookup_good) {
                dput(parent);
                /* Force unhash; the name doesn't point to this file
                 * anymore. */
@@ -1593,9 +1620,18 @@ afs_linux_lookup(struct inode *dip, struct dentry *dp)
     /* It's ok for the file to not be found. That's noted by the caller by
      * seeing that the dp->d_inode field is NULL.
      */
-    if (!code || code == ENOENT)
-       return newdp;
-    else 
+    if (!code || code == ENOENT) {
+       /*
+        * d_splice_alias can return an error (EIO) if there is an existing
+        * connected directory alias for this dentry.
+        */
+       if (!IS_ERR(newdp))
+           return newdp;
+       else {
+           d_add(dp, ip);
+           return NULL;
+       }
+    } else
        return ERR_PTR(afs_convert_code(code));
 }