From 2378826d96532b390bd4cb08d3946b497a9b0e51 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@fb.com>
Date: Tue, 12 May 2015 11:31:32 -0400
Subject: [PATCH] Add 'allow_file_create' option

For running certain jobs, it's convenient to tell fio that you never
want it to create files. On Linux, this prevents filling up /dev
with data for cases where the specified block device isn't available.

Signed-off-by: Jens Axboe <axboe@fb.com>
---
 HOWTO            |  5 +++++
 cconv.c          |  2 ++
 filesetup.c      | 16 ++++++++++++----
 fio.1            |  5 +++++
 options.c        |  9 +++++++++
 server.h         |  2 +-
 thread_options.h |  4 ++++
 7 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/HOWTO b/HOWTO
index 406cfca0..74475129 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1199,6 +1199,11 @@ create_only=bool	If true, fio will only run the setup phase of the job.
 			that will be done. The actual job contents are not
 			executed.
 
+allow_file_create=bool	If true, fio is permitted to create files as part
+		of its workload. This is the default behavior. If this
+		option is false, then fio will error out if the files it
+		needs to use don't already exist. Default: true.
+
 pre_read=bool	If this is given, files will be pre-read into memory before
 		starting the given IO operation. This will also clear
 		the 'invalidate' flag, since it is pointless to pre-read
diff --git a/cconv.c b/cconv.c
index bc9edb2d..b0becb8b 100644
--- a/cconv.c
+++ b/cconv.c
@@ -72,6 +72,7 @@ void convert_thread_options_to_cpu(struct thread_options *o,
 	string_to_cpu(&o->profile, top->profile);
 	string_to_cpu(&o->cgroup, top->cgroup);
 
+	o->allow_create = le32_to_cpu(top->allow_create);
 	o->td_ddir = le32_to_cpu(top->td_ddir);
 	o->rw_seq = le32_to_cpu(top->rw_seq);
 	o->kb_base = le32_to_cpu(top->kb_base);
@@ -288,6 +289,7 @@ void convert_thread_options_to_net(struct thread_options_pack *top,
 	string_to_net(top->profile, o->profile);
 	string_to_net(top->cgroup, o->cgroup);
 
+	top->allow_create = cpu_to_le32(o->allow_create);
 	top->td_ddir = cpu_to_le32(o->td_ddir);
 	top->rw_seq = cpu_to_le32(o->rw_seq);
 	top->kb_base = cpu_to_le32(o->kb_base);
diff --git a/filesetup.c b/filesetup.c
index aee7ece9..cf8ae94c 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -65,7 +65,9 @@ static int extend_file(struct thread_data *td, struct fio_file *f)
 		}
 	}
 
-	flags = O_WRONLY | O_CREAT;
+	flags = O_WRONLY;
+	if (td->o.allow_create)
+		flags |= O_CREAT;
 	if (new_layout)
 		flags |= O_TRUNC;
 
@@ -76,7 +78,13 @@ static int extend_file(struct thread_data *td, struct fio_file *f)
 	dprint(FD_FILE, "open file %s, flags %x\n", f->file_name, flags);
 	f->fd = open(f->file_name, flags, 0644);
 	if (f->fd < 0) {
-		td_verror(td, errno, "open");
+		int err = errno;
+
+		if (err == ENOENT && !td->o.allow_create)
+			log_err("fio: file creation disallowed by "
+					"allow_file_create=0\n");
+		else
+			td_verror(td, err, "open");
 		return 1;
 	}
 
@@ -539,7 +547,7 @@ int generic_open_file(struct thread_data *td, struct fio_file *f)
 	}
 	if (td->o.sync_io)
 		flags |= O_SYNC;
-	if (td->o.create_on_open)
+	if (td->o.create_on_open && td->o.allow_create)
 		flags |= O_CREAT;
 skip_flags:
 	if (f->filetype != FIO_TYPE_FILE)
@@ -550,7 +558,7 @@ open_again:
 		if (!read_only)
 			flags |= O_RDWR;
 
-		if (f->filetype == FIO_TYPE_FILE)
+		if (f->filetype == FIO_TYPE_FILE && td->o.allow_create)
 			flags |= O_CREAT;
 
 		if (is_std)
diff --git a/fio.1 b/fio.1
index 6c4e5c8f..d5e5536b 100644
--- a/fio.1
+++ b/fio.1
@@ -1075,6 +1075,11 @@ If true, fio will only run the setup phase of the job. If files need to be
 laid out or updated on disk, only that will be done. The actual job contents
 are not executed.
 .TP
+.BI allow_file_create \fR=\fPbool
+If true, fio is permitted to create files as part of its workload. This is
+the default behavior. If this option is false, then fio will error out if the
+files it needs to use don't already exist. Default: true.
+.TP
 .BI pre_read \fR=\fPbool
 If this is given, files will be pre-read into memory before starting the given
 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
diff --git a/options.c b/options.c
index 5c6ec232..ce1d11ef 100644
--- a/options.c
+++ b/options.c
@@ -3039,6 +3039,15 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 		.category = FIO_OPT_C_FILE,
 		.def	= "0",
 	},
+	{
+		.name	= "allow_file_create",
+		.type	= FIO_OPT_BOOL,
+		.off1	= td_var_offset(allow_create),
+		.help	= "Permit fio to create files, if they don't exist",
+		.def	= "1",
+		.category = FIO_OPT_C_FILE,
+		.group	= FIO_OPT_G_FILENAME,
+	},
 	{
 		.name	= "pre_read",
 		.lname	= "Pre-read files",
diff --git a/server.h b/server.h
index b0cea150..b94c2218 100644
--- a/server.h
+++ b/server.h
@@ -38,7 +38,7 @@ struct fio_net_cmd_reply {
 };
 
 enum {
-	FIO_SERVER_VER			= 44,
+	FIO_SERVER_VER			= 45,
 
 	FIO_SERVER_MAX_FRAGMENT_PDU	= 1024,
 	FIO_SERVER_MAX_CMD_MB		= 2048,
diff --git a/thread_options.h b/thread_options.h
index f967a8a1..aed39c80 100644
--- a/thread_options.h
+++ b/thread_options.h
@@ -270,6 +270,8 @@ struct thread_options {
 	unsigned int replay_scale;
 
 	unsigned int per_job_logs;
+
+	unsigned int allow_create;
 };
 
 #define FIO_TOP_STR_MAX		256
@@ -505,6 +507,8 @@ struct thread_options_pack {
 	uint32_t replay_scale;
 
 	uint32_t per_job_logs;
+
+	uint32_t allow_create;
 } __attribute__((packed));
 
 extern void convert_thread_options_to_cpu(struct thread_options *o, struct thread_options_pack *top);
-- 
2.25.1