posix-pstat/istat() - bail early if iatt structure is NULL

In some cases, we can return early - when iatt structure is NULL.
Specifically, this happens when we call those functions in part of
MAKE_INODE_HANDLE() macro - which in some cases is not using that structure.

This saves us few calls. Specifically, we do not need to fetch mdata xattr, which may save
us from some lgetxattr() and such.

Updates: gluster#1000
Signed-off-by: Yaniv Kaul <[email protected]>

xlators/storage/posix/src/posix-helpers.c

@@ -748,6 +748,12 @@ posix_istat(xlator_t *this, inode_t *inode, uuid_t gfid, const char *basename,
         return -1;
     }
 
+    if (!buf_p)
+        /* the rest of the code fills stbuf with more data. If it's not going to
+         * be copied over to buf_p, we can return here.
+         */
+        goto out;
+
     if (!S_ISDIR(lstatbuf.st_mode))
         lstatbuf.st_nlink--;
 
@@ -770,8 +776,7 @@ posix_istat(xlator_t *this, inode_t *inode, uuid_t gfid, const char *basename,
 
     posix_fill_ino_from_gfid(&stbuf);
 
-    if (buf_p)
-        memcpy(buf_p, &stbuf, sizeof(struct iatt));
+    memcpy(buf_p, &stbuf, sizeof(struct iatt));
 out:
     return ret;
 }
@@ -789,29 +794,30 @@ posix_pstat(xlator_t *this, inode_t *inode, uuid_t gfid, const char *path,
     int op_errno = 0;
     struct posix_private *priv = NULL;
 
-    priv = this->private;
-
     ret = sys_lstat(path, &lstatbuf);
     if (ret != 0) {
-        if (errno != ENOENT) {
-            op_errno = errno;
-            gf_msg(this->name, GF_LOG_WARNING, errno, P_MSG_LSTAT_FAILED,
+        op_errno = errno;
+        if (op_errno != ENOENT) {
+            gf_msg(this->name, GF_LOG_WARNING, op_errno, P_MSG_LSTAT_FAILED,
                    "lstat failed on %s", path);
-            errno = op_errno; /*gf_msg could have changed errno*/
         } else {
-            op_errno = errno;
-            gf_msg_debug(this->name, errno, "lstat failed on %s ", path);
-            errno = op_errno; /*gf_msg could have changed errno*/
+            gf_msg_debug(this->name, op_errno, "lstat failed on %s ", path);
         }
+        errno = op_errno; /*gf_msg could have changed errno*/
         goto out;
     }
 
+    priv = this->private;
+
     if ((lstatbuf.st_ino == priv->handledir_st_ino) &&
         (lstatbuf.st_dev == priv->handledir_st_dev)) {
         errno = ENOENT;
         return -1;
     }
 
+    if (!buf_p)
+        goto out;
+
     if (!S_ISDIR(lstatbuf.st_mode))
         lstatbuf.st_nlink--;
 
@@ -848,8 +854,7 @@ posix_pstat(xlator_t *this, inode_t *inode, uuid_t gfid, const char *path,
 
     posix_fill_ino_from_gfid(&stbuf);
 
-    if (buf_p)
-        memcpy(buf_p, &stbuf, sizeof(struct iatt));
+    memcpy(buf_p, &stbuf, sizeof(struct iatt));
 out:
     return ret;
 }