From: Jens Axboe <jaxboe@fusionio.com>
Date: Wed, 31 Aug 2011 19:14:12 +0000 (-0600)
Subject: Add support for backwards holes
X-Git-Tag: fio-1.58~14
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=a66da7a2354aac16757c75a824ad7cbba678535c;p=fio.git

Add support for backwards holes

If you did:

bs=4k
rw=read:-8k

you would essentially rewind by 8k after reading 4k, causing
the read to be sequentially backwards.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---

diff --git a/fio.h b/fio.h
index 0c86f288..8401eda7 100644
--- a/fio.h
+++ b/fio.h
@@ -254,7 +254,7 @@ struct thread_options {
 	unsigned int rw_seq;
 	unsigned int kb_base;
 	unsigned int ddir_seq_nr;
-	unsigned long ddir_seq_add;
+	long ddir_seq_add;
 	unsigned int iodepth;
 	unsigned int iodepth_low;
 	unsigned int iodepth_batch;
diff --git a/io_u.c b/io_u.c
index 7709df5f..16c98b1f 100644
--- a/io_u.c
+++ b/io_u.c
@@ -249,8 +249,12 @@ static int get_next_seq_block(struct thread_data *td, struct fio_file *f,
 	assert(ddir_rw(ddir));
 
 	if (f->last_pos < f->real_file_size) {
-		unsigned long long pos = f->last_pos - f->file_offset;
+		unsigned long long pos;
 
+		if (f->last_pos == f->file_offset && td->o.ddir_seq_add < 0)
+			f->last_pos = f->real_file_size;
+
+		pos = f->last_pos - f->file_offset;
 		if (pos)
 			pos += td->o.ddir_seq_add;