server: Implement file access hints using posix_fadvise.

configure

@@ -18010,6 +18010,7 @@ for ac_func in \
 	pipe2 \
 	poll \
 	port_create \
+	posix_fadvise \
 	prctl \
 	pread \
 	proc_pidinfo \

configure.ac

@@ -2186,6 +2186,7 @@ AC_CHECK_FUNCS(\
 	pipe2 \
 	poll \
 	port_create \
+	posix_fadvise \
 	prctl \
 	pread \
 	proc_pidinfo \

include/config.h.in

@@ -513,6 +513,9 @@
 /* Define to 1 if you have the <port.h> header file. */
 #undef HAVE_PORT_H
 
+/* Define to 1 if you have the `posix_fadvise' function. */
+#undef HAVE_POSIX_FADVISE
+
 /* Define to 1 if you have the `prctl' function. */
 #undef HAVE_PRCTL
 

server/fd.c

@@ -2026,6 +2026,19 @@ struct fd *open_fd( struct fd *root, const char *name, struct unicode_str nt_nam
         free( closed_fd );
         fd->cacheable = 1;
     }
+
+#ifdef HAVE_POSIX_FADVISE
+    switch (options & (FILE_SEQUENTIAL_ONLY | FILE_RANDOM_ACCESS))
+    {
+    case FILE_SEQUENTIAL_ONLY:
+        posix_fadvise( fd->unix_fd, 0, 0, POSIX_FADV_SEQUENTIAL );
+        break;
+    case FILE_RANDOM_ACCESS:
+        posix_fadvise( fd->unix_fd, 0, 0, POSIX_FADV_RANDOM );
+        break;
+    }
+#endif
+
     if (root_fd != -1) fchdir( server_dir_fd ); /* go back to the server dir */
     return fd;