nfs: generalises the code for making a LOOKUP rpc call

so that it can be used in a slightly different context in a following
patch. I also removed the caching of rpc call results that were failed for
errors other than ENOENT. For example, EPERM doesn't say anything about the
lookup validity for other credentials that might be used.

1 files changed, 44 insertions, 14 deletions

diff --git a/nfs/ops.c b/nfs/ops.c
index 175772e3..748d5530 100644
--- a/nfs/ops.c
+++ b/nfs/ops.c
@@ -27,6 +27,19 @@
 #include <maptime.h>
 #include <sys/sysmacros.h>
 
+/* Rules for locking/unlocking of 'struct node'->lock
+   applicable throughout the whole module:
+   1) Only lock a single node at a time except when
+   2) A new node is created beneath a directory when the
+   directory node->lock is held but
+   3) Once the directory lock is released then 2) no
+   longer applies and rule 1) applies to the new node.
+*/
+
+static error_t
+nfs_lookup_rpc (struct iouser *cred, struct node *np,
+		const char *name, struct node **newnp);
+
 /* We have fresh stat information for NP; the file attribute (fattr)
    structure is at P.  Update our entry.  Return the address of the next
    int after the fattr structure.  */
@@ -736,12 +749,6 @@ error_t
 netfs_attempt_lookup (struct iouser *cred, struct node *np,
 		      const char *name, struct node **newnp)
 {
-  int *p;
-  void *rpcbuf;
-  error_t err;
-  char dirhandle[NFS3_FHSIZE];
-  size_t dirlen;
-
   /* Check the cache first. */
   *newnp = check_lookup_cache (np, name);
   if (*newnp)
@@ -755,6 +762,23 @@ netfs_attempt_lookup (struct iouser *cred, struct node *np,
 	return 0;
     }
 
+  return nfs_lookup_rpc (cred, np, name, newnp);
+}
+
+/* LOOKUP rpc call to refetch the status of 'name' in directory
+   'np' which is supplied locked. Any '*newnp' supplied should be
+   unlocked and will be recached with the returned handle. On
+   return 'np' is unlocked and any '*newnp' is locked. */
+static error_t
+nfs_lookup_rpc (struct iouser *cred, struct node *np,
+		const char *name, struct node **newnp)
+{
+  int *p;
+  void *rpcbuf;
+  error_t err;
+  char dirhandle[NFS3_FHSIZE];
+  size_t dirlen;
+
   p = nfs_initialize_rpc (NFSPROC_LOOKUP (protocol_version),
 			  cred, 0, &rpcbuf, np, -1);
   if (! p)
@@ -780,27 +804,33 @@ netfs_attempt_lookup (struct iouser *cred, struct node *np,
       p++;
       if (!err)
 	{
-	  p = xdr_decode_fhandle (p, newnp);
+	  if (*newnp != NULL)
+	    {
+	      pthread_mutex_lock (&(*newnp)->lock);
+	      p = recache_handle (p, *newnp);
+	    }
+	  else
+	    p = xdr_decode_fhandle (p, newnp);
+
 	  p = process_returned_stat (*newnp, p, 1);
 	}
-      if (err)
-	*newnp = 0;
       if (protocol_version == 3)
 	{
 	  if (*newnp)
 	    pthread_mutex_unlock (&(*newnp)->lock);
 	  pthread_mutex_lock (&np->lock);
-	  p = process_returned_stat (np, p, 0); /* XXX Do we have to lock np? */
+	  p = process_returned_stat (np, p, 0);
 	  pthread_mutex_unlock (&np->lock);
 	  if (*newnp)
 	    pthread_mutex_lock (&(*newnp)->lock);
 	}
     }
-  else
-    *newnp = 0;
 
-  /* Notify the cache of the hit or miss. */
-  enter_lookup_cache (dirhandle, dirlen, *newnp, name);
+  if (!err || err == ENOENT)
+    {
+      /* Notify the cache of the hit or miss. */
+      enter_lookup_cache (dirhandle, dirlen, *newnp, name);
+    }
 
   free (rpcbuf);