Added implementation for files space preallocation

Signed-off-by: Slava Zanko <slavazanko@gmail.com>

lib/vfs/vfs.c

@@ -594,3 +594,42 @@ vfs_change_encoding (vfs_path_t * vpath, const char *encoding)
 }
 
 /* --------------------------------------------------------------------------------------------- */
+
+/**
+ * Preallocate space for file in new place for ensure that file
+ * will be fully copied with less fragmentation.
+ *
+ * @param dest_desc mc VFS file handler
+ * @param src_fsize source file size
+ * @param dest_fsize destination file size (if destination exists, otherwise should be 0)
+ *
+ * @return 0 if success and non-zero otherwise.
+ * Note: function doesn't touch errno global variable.
+ */
+int
+vfs_preallocate (int dest_vfs_fd, off_t src_fsize, off_t dest_fsize)
+{
+#ifndef HAVE_POSIX_FALLOCATE
+    (void) dest_desc;
+    (void) src_fsize;
+    (void) dest_fsize;
+    return 0;
+
+#else /* HAVE_POSIX_FALLOCATE */
+    int *dest_fd;
+    struct vfs_class *dest_class;
+
+    dest_class = vfs_class_find_by_handle (dest_vfs_fd);
+    if ((dest_class->flags & VFSF_LOCAL) == 0)
+        return 0;
+
+    dest_fd = (int *) vfs_class_data_find_by_handle (dest_vfs_fd);
+    if (dest_fd == NULL)
+        return 0;
+
+    return posix_fallocate (*dest_fd, dest_fsize, src_fsize - dest_fsize);
+
+#endif /* HAVE_POSIX_FALLOCATE */
+}
+
+/* --------------------------------------------------------------------------------------------- */

lib/vfs/vfs.h

@@ -268,6 +268,8 @@ char *_vfs_get_cwd (void);
 
 vfs_path_t *vfs_change_encoding (vfs_path_t * vpath, const char *encoding);
 
+int vfs_preallocate (int dest_desc, off_t src_fsize, off_t dest_fsize);
+
 /**
  * Interface functions described in interface.c
  */

src/filemanager/file.c

@@ -1504,6 +1504,27 @@ copy_file_file (FileOpTotalContext * tctx, FileOpContext * ctx,
             ctx->skip_all = TRUE;
         goto ret;
     }
+    while (TRUE)
+    {
+        errno = vfs_preallocate (dest_desc, file_size, (ctx->do_append != 0) ? sb.st_size : 0);
+        if (errno == 0)
+            break;
+
+        if (!ctx->skip_all)
+        {
+            return_status =
+                file_error (_("Cannot preallocate space for target file \"%s\"\n%s"), dst_path);
+            if (return_status == FILE_RETRY)
+                continue;
+            if (return_status == FILE_SKIPALL)
+                ctx->skip_all = TRUE;
+        }
+        mc_close (dest_desc);
+        dest_desc = -1;
+        mc_unlink (dst_path);
+        dst_status = DEST_NONE;
+        goto ret;
+    }
 
     ctx->eta_secs = 0.0;
     ctx->bps = 0;