Only overwrite in layout if needed

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/filesetup.c b/filesetup.c
index f6b4855bbe7a845a9549fd45e65b99aed2477d41..2da29d1510ad2ed5cccba9d6d38ccd7d15322ec8 100644 (file)
--- a/filesetup.c
+++ b/filesetup.c
@@ -12,19 +12,31 @@
 
 static int extend_file(struct thread_data *td, struct fio_file *f)
 {
+       int r, new_layout = 0, flags;
        unsigned long long left;
        unsigned int bs;
        char *b;
-       int r;
 
-       if (f->flags & FIO_FILE_EXISTS) {
+       /*
+        * check if we need to lay the file out complete again. fio
+        * does that for operations involving reads, or for writes
+        * where overwrite is set
+        */
+       if (td_read(td) || (td_write(td) && td->o.overwrite))
+               new_layout = 1;
+
+       if (new_layout && (f->flags & FIO_FILE_EXISTS)) {
                if (unlink(f->file_name) < 0) {
                        td_verror(td, errno, "unlink");
                        return 1;
                }
        }
 
-       f->fd = open(f->file_name, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+       flags = O_WRONLY | O_CREAT;
+       if (new_layout)
+               flags |= O_TRUNC;
+
+       f->fd = open(f->file_name, flags, 0644);
        if (f->fd < 0) {
                td_verror(td, errno, "open");
                return 1;
@@ -40,6 +52,9 @@ static int extend_file(struct thread_data *td, struct fio_file *f)
                goto err;
        }
 
+       if (!new_layout)
+               goto done;
+
        b = malloc(td->o.max_bs[DDIR_WRITE]);
        memset(b, 0, td->o.max_bs[DDIR_WRITE]);
 
@@ -70,6 +85,7 @@ static int extend_file(struct thread_data *td, struct fio_file *f)
                fsync(f->fd);
 
        free(b);
+done:
        close(f->fd);
        f->fd = -1;
        return 0;