From: Jens Axboe <jens.axboe@oracle.com>
Date: Wed, 7 Feb 2007 12:14:57 +0000 (+0100)
Subject: [PATCH] Don't create files for engines that don't need them
X-Git-Tag: fio-1.12~128
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=4d9345ae968ca92ace3dab06c25a9b73159cb329

[PATCH] Don't create files for engines that don't need them

Introduce FIO_NULLIO as a way to control that from the io engine.

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

diff --git a/engines/cpu.c b/engines/cpu.c
index f65f91d9..27ec6da1 100644
--- a/engines/cpu.c
+++ b/engines/cpu.c
@@ -24,7 +24,7 @@ static struct ioengine_ops ioengine = {
 	.version	= FIO_IOOPS_VERSION,
 	.init		= fio_cpuio_init,
 	.setup		= fio_cpuio_setup,
-	.flags		= FIO_CPUIO,
+	.flags		= FIO_CPUIO | FIO_NULLIO,
 };
 
 static void fio_init fio_cpuio_register(void)
diff --git a/engines/null.c b/engines/null.c
index fc829473..7b4b2176 100644
--- a/engines/null.c
+++ b/engines/null.c
@@ -70,7 +70,7 @@ static struct ioengine_ops ioengine = {
 	.getevents	= fio_null_getevents,
 	.event		= fio_null_event,
 	.cleanup	= fio_null_cleanup,
-	.flags		= FIO_SYNCIO,
+	.flags		= FIO_SYNCIO | FIO_NULLIO,
 };
 
 static void fio_init fio_null_register(void)
diff --git a/filesetup.c b/filesetup.c
index 610981b4..1f1259d1 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -15,7 +15,7 @@ static int file_ok(struct thread_data *td, struct fio_file *f)
 {
 	struct stat st;
 
-	if (td->filetype != FIO_TYPE_FILE)
+	if (td->filetype != FIO_TYPE_FILE || (td->io_ops->flags & FIO_NULLIO))
 		return 0;
 
 	if (stat(f->file_name, &st) == -1)
@@ -332,29 +332,38 @@ static int setup_file(struct thread_data *td, struct fio_file *f)
 
 	if (td->io_ops->flags & FIO_NETIO)
 		return 0;
-	if (td->odirect)
-		flags |= OS_O_DIRECT;
-	if (td->sync_io)
-		flags |= O_SYNC;
 
-	if (td_write(td) || td_rw(td)) {
-		flags |= O_RDWR;
+	/*
+	 * we need a valid file descriptor, but don't create a real file.
+	 * lets just dup stdout, seems like a sensible approach.
+	 */
+	if (td->io_ops->flags & FIO_NULLIO)
+		f->fd = dup(STDOUT_FILENO);
+	else {
+		if (td->odirect)
+			flags |= OS_O_DIRECT;
+		if (td->sync_io)
+			flags |= O_SYNC;
+
+		if (td_write(td) || td_rw(td)) {
+			flags |= O_RDWR;
 
-		if (td->filetype == FIO_TYPE_FILE) {
-			if (!td->overwrite)
-				flags |= O_TRUNC;
+			if (td->filetype == FIO_TYPE_FILE) {
+				if (!td->overwrite)
+					flags |= O_TRUNC;
 
-			flags |= O_CREAT;
-		}
+				flags |= O_CREAT;
+			}
 
-		f->fd = open(f->file_name, flags, 0600);
-	} else {
-		if (td->filetype == FIO_TYPE_CHAR)
-			flags |= O_RDWR;
-		else
-			flags |= O_RDONLY;
+			f->fd = open(f->file_name, flags, 0600);
+		} else {
+			if (td->filetype == FIO_TYPE_CHAR)
+				flags |= O_RDWR;
+			else
+				flags |= O_RDONLY;
 
-		f->fd = open(f->file_name, flags);
+			f->fd = open(f->file_name, flags);
+		}
 	}
 
 	if (f->fd == -1) {
diff --git a/fio.h b/fio.h
index 56ed2485..e42d67bb 100644
--- a/fio.h
+++ b/fio.h
@@ -147,6 +147,7 @@ enum fio_ioengine_flags {
 	FIO_MMAPIO	= 1 << 2,
 	FIO_RAWIO	= 1 << 3,
 	FIO_NETIO	= 1 << 4,
+	FIO_NULLIO	= 1 << 5,
 };
 
 struct fio_file {
diff --git a/stat.c b/stat.c
index a98539fc..a9e87aa7 100644
--- a/stat.c
+++ b/stat.c
@@ -205,7 +205,7 @@ void init_disk_util(struct thread_data *td)
 	dev_t dev;
 	char *p;
 
-	if (!td->do_disk_util || (td->io_ops->flags & FIO_NETIO))
+	if (!td->do_disk_util || (td->io_ops->flags & (FIO_NETIO | FIO_NULLIO)))
 		return;
 
 	/*