sunrpc/cache: recheck cache validity after cache_defer_req

If cache_defer_req did not leave the request on a queue, then it could
possibly have waited long enough that the cache became valid.  So check the
status after the call.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 44f4516..bbd31f1 100644 (file)
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -176,6 +176,22 @@ struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 EXPORT_SYMBOL_GPL(sunrpc_cache_update);
 
 static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
+
+static inline int cache_is_valid(struct cache_detail *detail, struct cache_head *h)
+{
+       if (!test_bit(CACHE_VALID, &h->flags) ||
+           h->expiry_time < get_seconds())
+               return -EAGAIN;
+       else if (detail->flush_time > h->last_refresh)
+               return -EAGAIN;
+       else {
+               /* entry is valid */
+               if (test_bit(CACHE_NEGATIVE, &h->flags))
+                       return -ENOENT;
+               else
+                       return 0;
+       }
+}
 /*
  * This is the generic cache management routine for all
  * the authentication caches.
@@ -184,8 +200,10 @@ static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
  *
  *
  * Returns 0 if the cache_head can be used, or cache_puts it and returns
- * -EAGAIN if upcall is pending,
- * -ETIMEDOUT if upcall failed and should be retried,
+ * -EAGAIN if upcall is pending and request has been queued
+ * -ETIMEDOUT if upcall failed or request could not be queue or
+ *           upcall completed but item is still invalid (implying that
+ *           the cache item has been replaced with a newer one).
  * -ENOENT if cache entry was negative
  */
 int cache_check(struct cache_detail *detail,
@@ -195,17 +213,7 @@ int cache_check(struct cache_detail *detail,
        long refresh_age, age;
 
        /* First decide return status as best we can */
-       if (!test_bit(CACHE_VALID, &h->flags) ||
-           h->expiry_time < get_seconds())
-               rv = -EAGAIN;
-       else if (detail->flush_time > h->last_refresh)
-               rv = -EAGAIN;
-       else {
-               /* entry is valid */
-               if (test_bit(CACHE_NEGATIVE, &h->flags))
-                       rv = -ENOENT;
-               else rv = 0;
-       }
+       rv = cache_is_valid(detail, h);
 
        /* now see if we want to start an upcall */
        refresh_age = (h->expiry_time - h->last_refresh);
@@ -238,10 +246,14 @@ int cache_check(struct cache_detail *detail,
                }
        }
 
-       if (rv == -EAGAIN)
-               if (cache_defer_req(rqstp, h) != 0)
-                       rv = -ETIMEDOUT;
-
+       if (rv == -EAGAIN) {
+               if (cache_defer_req(rqstp, h) == 0) {
+                       /* Request is not deferred */
+                       rv = cache_is_valid(detail, h);
+                       if (rv == -EAGAIN)
+                               rv = -ETIMEDOUT;
+               }
+       }
        if (rv)
                cache_put(h, detail);
        return rv;
@@ -560,11 +572,11 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item)
                 * or continue and drop the oldest below
                 */
                if (net_random()&1)
-                       return -ETIMEDOUT;
+                       return 0;
        }
        dreq = req->defer(req);
        if (dreq == NULL)
-               return -ETIMEDOUT;
+               return 0;
 
        dreq->item = item;
 
@@ -594,8 +606,9 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item)
        if (!test_bit(CACHE_PENDING, &item->flags)) {
                /* must have just been validated... */
                cache_revisit_request(item);
+               return 0;
        }
-       return 0;
+       return 1;
 }
 
 static void cache_revisit_request(struct cache_head *item)