From 453b1627d3ba2541845e223a1512933e007470c8 Mon Sep 17 00:00:00 2001
From: Juan Casse <jcasse@chromium.org>
Date: Sun, 15 Sep 2013 16:47:59 -0700
Subject: [PATCH V3] Adds verify_only option

When this option is set, a dry run (no actual io is performed) of the
workload will be done in order to compute the numberio for each block
header without overwriting the data on disk. Then, do_verify() will be
effectively verifying data that was written in a previous fio run.
In the case that "loops" is set to more than 1, do_verify() will delay
the verification of numberio to the last iteration when the same
numberio state that would have been written to disk in a previous
fio run has been reached.

Signed-off-by: Juan Casse <jcasse@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
---
This patch depends on "[PATCH] Adds check for numberio during verify phase"
sent on September 5, 2013.

 HOWTO            | 11 ++++++++++-
 README           |  2 ++
 backend.c        | 43 ++++++++++++++++++++++++++++++++++++++++++-
 init.c           | 17 +++++++++++++++++
 options.c        |  9 +++++++++
 thread_options.h |  2 ++
 verify.c         |  8 ++++++--
 7 files changed, 88 insertions(+), 4 deletions(-)

diff --git a/HOWTO b/HOWTO
index 005dac2..a3ca770 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1039,6 +1039,13 @@ loops=int	Run the specified number of iterations of this job. Used
 		to repeat the same workload a given number of times. Defaults
 		to 1.
 
+verify_only	Do not perform specified workload---only verify data still
+		matches previous invocation of this workload. This option
+		allows one to check data multiple times at a later date
+		without overwriting it. This option makes sense only for
+		workloads that write data, and does not support workloads
+		with the time_based option set.
+
 do_verify=bool	Run the verify phase after a write phase. Only makes sense if
 		verify is set. Defaults to 1.
 
@@ -1077,7 +1084,9 @@ verify=str	If writing to a file, fio can verify the file contents
 
 			meta	Write extra information about each io
 				(timestamp, block number etc.). The block
-				number is verified. See also verify_pattern.
+				number is verified. The io sequence number is
+				verified for workloads that write data.
+				See also verify_pattern.
 
 			null	Only pretend to verify. Useful for testing
 				internals with ioengine=null, not for much
diff --git a/README b/README
index 15a0731..7942069 100644
--- a/README
+++ b/README
@@ -141,6 +141,8 @@ $ fio
 	--latency-log		Generate per-job latency logs
 	--bandwidth-log		Generate per-job bandwidth logs
 	--minimal		Minimal (terse) output
+	--verifyonly		Skip workload io and only verify data
+				(includes stale data check)
 	--output-format=type	Output format (terse,json,normal)
 	--terse-version=type	Terse version output format (default 3, or 2 or 4).
 	--version		Print version info and exit
diff --git a/backend.c b/backend.c
index b9c1c12..c74c001 100644
--- a/backend.c
+++ b/backend.c
@@ -1104,6 +1104,44 @@ static int exec_string(struct thread_options *o, const char *string, const char
 }
 
 /*
+ * Dry run to compute correct state of numberio for verification.
+ */
+static uint64_t do_dry_run(struct thread_data *td)
+{
+	uint64_t bytes_done[DDIR_RWDIR_CNT] = { 0, 0, 0 };
+
+	td_set_runstate(td, TD_RUNNING);
+
+	while ((td->o.read_iolog_file && !flist_empty(&td->io_log_list)) ||
+		(!flist_empty(&td->trim_list)) || !io_bytes_exceeded(td)) {
+		struct io_u *io_u;
+		int ret;
+
+		if (td->terminate || td->done)
+			break;
+
+		io_u = get_io_u(td);
+		if (!io_u)
+			break;
+
+		io_u->flags |= IO_U_F_FLIGHT;
+		io_u->error = 0;
+		io_u->resid = 0;
+		if (ddir_rw(acct_ddir(io_u)))
+			td->io_issues[acct_ddir(io_u)]++;
+		if (ddir_rw(io_u->ddir)) {
+			io_u_mark_depth(td, 1);
+			td->ts.total_io_u[io_u->ddir]++;
+		}
+
+		ret = io_u_sync_complete(td, io_u, bytes_done);
+		(void) ret;
+	}
+
+	return bytes_done[DDIR_WRITE] + bytes_done[DDIR_TRIM];
+}
+
+/*
  * Entry point for the thread based jobs. The process based jobs end up
  * here as well, after a little setup.
  */
@@ -1311,7 +1349,10 @@ static void *thread_main(void *data)
 
 		prune_io_piece_log(td);
 
-		verify_bytes = do_io(td);
+		if (td->o.verify_only && (td_write(td) || td_rw(td)))
+			verify_bytes = do_dry_run(td);
+		else
+			verify_bytes = do_io(td);
 
 		clear_state = 1;
 
diff --git a/init.c b/init.c
index 1afc341..34d1f14 100644
--- a/init.c
+++ b/init.c
@@ -60,6 +60,8 @@ int write_bw_log = 0;
 int read_only = 0;
 int status_interval = 0;
 
+int verify_only = 0;
+
 static int write_lat_log;
 
 static int prev_group_jobs;
@@ -139,6 +141,11 @@ static struct option l_opts[FIO_NR_OPTIONS] = {
 		.val		= 'r' | FIO_CLIENT_FLAG,
 	},
 	{
+		.name		= (char *) "verifyonly",
+		.has_arg	= no_argument,
+		.val		= 'y' | FIO_CLIENT_FLAG,
+	},
+	{
 		.name		= (char *) "eta",
 		.has_arg	= required_argument,
 		.val		= 'e' | FIO_CLIENT_FLAG,
@@ -928,6 +935,13 @@ static int add_job(struct thread_data *td, const char *jobname, int job_add_num,
 	int numjobs, file_alloced;
 	struct thread_options *o = &td->o;
 
+	/* 
+	 * Ensure job option verify_only is set when provided as a
+	 * command-line argument.
+	 */
+	if (verify_only)
+		o->verify_only = 1;
+
 	/*
 	 * the def_thread is just for options, it's not a real job
 	 */
@@ -1661,6 +1675,9 @@ int parse_cmd_line(int argc, char *argv[], int client_type)
 		case 'r':
 			read_only = 1;
 			break;
+		case 'y':
+			verify_only = 1;
+			break;
 		case 'v':
 			if (!cur_client) {
 				log_info("%s\n", fio_version_string);
diff --git a/options.c b/options.c
index caf89d3..e6b9ec9 100644
--- a/options.c
+++ b/options.c
@@ -1935,6 +1935,15 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 		.group	= FIO_OPT_G_RUNTIME,
 	},
 	{
+		.name	= "verify_only",
+		.lname	= "Verify only",
+		.type	= FIO_OPT_STR_SET,
+		.off1	= td_var_offset(verify_only),
+		.help	= "Verifies previously written data is still valid",
+		.category = FIO_OPT_C_GENERAL,
+		.group	= FIO_OPT_G_RUNTIME,
+	},
+	{
 		.name	= "ramp_time",
 		.lname	= "Ramp time",
 		.type	= FIO_OPT_STR_VAL_TIME,
diff --git a/thread_options.h b/thread_options.h
index 3f345c5..c9660b4 100644
--- a/thread_options.h
+++ b/thread_options.h
@@ -107,6 +107,8 @@ struct thread_options {
 	unsigned int fsync_on_close;
 	unsigned int bs_is_seq_rand;
 
+	unsigned int verify_only;
+
 	unsigned int random_distribution;
 
 	fio_fp64_t zipf_theta;
diff --git a/verify.c b/verify.c
index 63def12..9343ab9 100644
--- a/verify.c
+++ b/verify.c
@@ -373,10 +373,14 @@ static int verify_io_u_meta(struct verify_header *hdr, struct vcont *vc)
 	 * For read-only workloads, the program cannot be certain of the
 	 * last numberio written to a block. Checking of numberio will be done
 	 * only for workloads that write data.
+	 * For verify_only, numberio will be checked in the last iteration when
+	 * the correct state of numberio, that would have been written to each
+	 * block in a previous run of fio, has been reached.
 	 */
 	if (td_write(td) || td_rw(td))
-		if (vh->numberio != io_u->numberio)
-			ret = EILSEQ;
+		if (!td->o.verify_only || td->o.loops == 0)
+			if (vh->numberio != io_u->numberio)
+				ret = EILSEQ;
 
 	if (!ret)
 		return 0;
-- 
1.7.12.4