From a61154fd93122f5a0f2b74f21c3ac29eb437f150 Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@suse.de>
Date: Fri, 6 Oct 2017 09:39:36 +0200
Subject: [PATCH] dasdfmt: Format devices in parallel

Allow dasdfmt to run in parallel when several devices are specified.

Signed-off-by: Hannes Reinecke <hare@suse.com>
---
 dasdfmt/dasdfmt.8 | 16 ++++++++++++++--
 dasdfmt/dasdfmt.c | 50 +++++++++++++++++++++++++++++++++++++++++++-------
 dasdfmt/dasdfmt.h |  1 +
 3 files changed, 58 insertions(+), 9 deletions(-)

diff --git a/dasdfmt/dasdfmt.8 b/dasdfmt/dasdfmt.8
index e7fc501..07c674b 100644
--- a/dasdfmt/dasdfmt.8
+++ b/dasdfmt/dasdfmt.8
@@ -7,7 +7,7 @@
 dasdfmt \- formatting of DASD (ECKD) disk drives.
 
 .SH SYNOPSIS
-\fBdasdfmt\fR [-h] [-t] [-v] [-y] [-p] [-P] [-m \fIstep\fR]
+\fBdasdfmt\fR [-h] [-t] [-v] [-y] [-p] [-Q] [-P] [-m \fIstep\fR]
 .br
         [-r \fIcylinder\fR] [-b \fIblksize\fR] [-l \fIvolser\fR] [-d \fIlayout\fR]
 .br
@@ -96,7 +96,7 @@ Do not use this option if you are using a 3270 console,
 running in background or redirecting the output to a file.
 
 .TP
-\fB-P\fR or \fB--percentage\fR
+\fB-Q\fR or \fB--percentage\fR
 Print one line for each formatted cylinder showing the number of the
 cylinder and percentage of formatting process.
 Intended to be used by higher level interfaces.
@@ -159,6 +159,18 @@ Specify blocksize to be used. \fIblksize\fR must be a positive integer
 and always be a power of two. The recommended blocksize is 4096 bytes.
 
 .TP
+\fB-P\fR \fInumdisks\fR or \fB--max_parallel\fR=\fInumdisks\fR
+Specify the number of disks to be formatted in parallel.
+\fInumdisks\fR specifies the number of formatting processed,
+independent on the overall number of disks to be formatted.
+The maximum value for \fInumdisks\fR is 512. Default is 1.
+.br
+Using this option can decrease overall processing time when formatting
+several disks. Please note that the I/O throughput will dramatically
+increase when using this option. Use with care.
+.br
+
+.TP
 \fB-l\fR \fIvolser\fR or \fB--label\fR=\fIvolser\fR
 Specify the volume serial number or volume identifier to be written 
 to disk after formatting. If no label is specified, a sensible default 
--- s390-tools-2.15.1/dasdfmt/dasdfmt.c	2020-12-04 23:22:51.418265761 +0100
+++ s390-tools-2.15.1/dasdfmt/dasdfmt.c	2020-12-04 23:29:26.165601000 +0100
@@ -13,6 +13,7 @@
 #include <sys/sysmacros.h>
 #include <sys/time.h>
 #include <sys/utsname.h>
+#include <sys/wait.h>
 
 #include "lib/dasd_base.h"
 #include "lib/dasd_sys.h"
@@ -81,6 +82,7 @@
 	int   mode_specified;
 	int   ese;
 	int   no_discard;
+	int   procnum;
 } g = {
 	.dasd_info = { 0 },
 };
@@ -105,6 +107,11 @@
 		.desc = "Perform complete format check on device",
 		.flags = UTIL_OPT_FLAG_NOSHORT,
 	},
+	{
+		.option = { "max_parallel", required_argument, NULL, 'P' },
+		.desc = "Format devices in parallel",
+		.flags = UTIL_OPT_FLAG_NOLONG,
+	},
 	UTIL_OPT_SECTION("FORMAT OPTIONS"),
 	{
 		.option = { "blocksize", required_argument, NULL, 'b' },
@@ -162,7 +170,7 @@
 		.desc = "Show a progressbar",
 	},
 	{
-		.option = { "percentage", no_argument, NULL, 'P' },
+		.option = { "percentage", no_argument, NULL, 'Q' },
 		.desc = "Show progress in percent",
 	},
 	UTIL_OPT_SECTION("MISC"),
@@ -311,7 +318,7 @@
 	}
 
 	if (g.print_hashmarks && (cyl / g.hashstep - hashcount) != 0) {
-		printf("#");
+		printf("%d|", g.procnum);
 		fflush(stdout);
 		hashcount++;
 	}
@@ -1560,7 +1568,11 @@
 	char *reqsize_param_str = NULL;
 	char *hashstep_str      = NULL;
 
-	int rc, numdev = 0, i;
+	int rc, numdev = 0, numproc = 0, status;
+	int max_parallel =1 ;
+	int running = 0;
+	int chpid;
+	int tmp;
 
 	/* Establish a handler for interrupt signals. */
 	signal(SIGTERM, program_interrupt_signal);
@@ -1623,7 +1635,7 @@
 				g.print_hashmarks = 1;
 			}
 			break;
-		case 'P':
+		case 'Q':
 			if (!(g.print_hashmarks || g.print_progressbar))
 				g.print_percentage = 1;
 			break;
@@ -1682,6 +1694,9 @@
 		case OPT_NODISCARD:
 			g.no_discard = 1;
 			break;
+		case 'P':
+			max_parallel = atoi(optarg);
+			break;
 		case OPT_CHECK:
 			g.check = 1;
 			break;
@@ -1733,15 +1748,35 @@
 	if (numdev > 1 && g.labelspec)
 		error("Specifying a volser to be written doesn't make sense when formatting multiple DASD volumes.");
 
-	for (i = 0; i < numdev; i++)
-	{
-		strncpy(g.dev_path, g.dev_path_array[i], strlen(g.dev_path_array[i])+1);
-		strncpy(g.dev_node, g.dev_node_array[i], strlen(g.dev_node_array[i])+1);	
-		process_dasd(&vlabel, format_params);
+	for (numproc = 0; numproc < numdev; numproc++) {
+		chpid = fork();
+		if (chpid == -1 )
+			ERRMSG_EXIT(EXIT_FAILURE,
+					"%s: Unable to create child process: %s\n",
+					prog_name, strerror(errno));
+		if (!chpid) {
+				g.procnum = numproc;
+				strncpy(g.dev_path, g.dev_path_array[numproc], strlen(g.dev_path_array[numproc])+1);
+				strncpy(g.dev_node, g.dev_node_array[numproc], strlen(g.dev_node_array[numproc])+1);
+				process_dasd(&vlabel, format_params);
+
+				free(g.dev_path);
+				free(g.dev_node);
+				exit(0);
+		} else {
+			running++;
+			if (running >= max_parallel) {
+				if (wait(&tmp) > 0 && WEXITSTATUS(tmp))
+					rc = WEXITSTATUS(tmp);
+				running--;
+			}
+		}
 	}
 
-	free(g.dev_path);
-	free(g.dev_node);
+	/* wait until all formatting children have finished */
+	while(wait(&status) > 0)
+		if (WEXITSTATUS(status))
+			rc = WEXITSTATUS(status);
 
-	return 0;
+       return rc;
 }
