performance/stat-prefetch: change behaviour of sp_lookup when xattr_req is not NULL.

- if the xattr_req is empty (fuse just creates an empty dictionary and
    sends along lookup) we can still use the cache prefetched during readdir,
    since we need not fill the reply dictionary.

Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 284 (performance actually decreases for 'ls -l' on a directory containing large number of files with stat-prefetch loaded)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=284

1 files changed, 27 insertions, 7 deletions

diff --git a/xlators/performance/stat-prefetch/src/stat-prefetch.c b/xlators/performance/stat-prefetch/src/stat-prefetch.c
index d44aa4949..1b19a58d1 100644
--- a/xlators/performance/stat-prefetch/src/stat-prefetch.c
+++ b/xlators/performance/stat-prefetch/src/stat-prefetch.c
@@ -494,22 +494,42 @@ out:
 }
 
 
+void
+sp_is_empty (dict_t *this, char *key, data_t *value, void *data)
+{
+        char *ptr = data;
+
+        if (ptr && *ptr) {
+                *ptr = 0;
+        }
+}
+
+
 int32_t
 sp_lookup (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *xattr_req)
 {
-        sp_local_t   *local      = NULL;
+        sp_local_t   *local              = NULL;
         gf_dirent_t   dirent;     
-        int32_t       ret        = -1, op_ret = -1, op_errno = EINVAL; 
-        sp_cache_t   *cache      = NULL;
-        struct stat  *postparent = NULL, *buf = NULL;
-        call_frame_t *wind_frame = NULL;
-        char          lookup_behind = 0;
+        int32_t       ret                = -1, op_ret = -1, op_errno = EINVAL; 
+        sp_cache_t   *cache              = NULL;
+        struct stat  *postparent         = NULL, *buf = NULL;
+        call_frame_t *wind_frame         = NULL;
+        char          lookup_behind      = 0;
+        char          xattr_req_empty    = 1;
 
         if (loc == NULL) {
                 goto unwind;
         }
 
-        if (xattr_req || (loc->parent == NULL) || (loc->name == NULL)) {
+        if ((loc->parent == NULL) || (loc->name == NULL)) {
+                goto wind;
+        }
+
+        if (xattr_req != NULL) {
+                dict_foreach (xattr_req, sp_is_empty, &xattr_req_empty);
+        }
+
+        if (!xattr_req_empty) {
                 goto wind;
         }