From ea63e29a34037b91e9b2cc2ec37e43bf302b682d Mon Sep 17 00:00:00 2001
From: Manuel Bentele
Date: Tue, 10 Nov 2020 08:29:18 +0100
Subject: [CLIENT] display proper connected server if multiple servers
 specified

With this change, the dnbd3-client is able to display the selected
server (choosen by the Linux kernel module) after successful probing.
Therefore, the ioctl call OPEN returns the selected server host as
index of the specified dnbd3-server hosts after successful probing.
---
 src/client/client.c | 30 ++++++++++++++++++------------
 src/kernel/blk.c    |  4 ++--
 2 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/src/client/client.c b/src/client/client.c
index fd2770f..261edb7 100644
--- a/src/client/client.c
+++ b/src/client/client.c
@@ -237,6 +237,7 @@ int main(int argc, char *argv[])
 
 	int action = -1;
 	bool learnNewServers = true;
+	int active_device_num = 0;
 
 	dnbd3_ioctl_t msg;
 	memset( &msg, 0, sizeof(dnbd3_ioctl_t) );
@@ -335,32 +336,37 @@ int main(int argc, char *argv[])
 		setuid( getuid() );
 	}
 
-	host_to_string( &msg.hosts[0], host, 50 );
-
 	// close device
 	if ( action == IOCTL_CLOSE && msg.hosts_num == 0 && dev && (msg.imgname == NULL )) {
 		printf( "INFO: Closing device %s\n", dev );
-		if ( dnbd3_ioctl( dev, IOCTL_CLOSE, &msg ) ) exit( EXIT_SUCCESS );
+		if ( dnbd3_ioctl( dev, IOCTL_CLOSE, &msg ) == 0 ) exit( EXIT_SUCCESS );
 		printf( "Couldn't close device.\n" );
 		exit( EXIT_FAILURE );
 	}
 
 	// switch host
 	if ( (action == IOCTL_SWITCH || action == IOCTL_ADD_SRV || action == IOCTL_REM_SRV) && msg.hosts_num == 1 && dev && (msg.imgname == NULL )) {
+		host_to_string( &msg.hosts[0], host, 50 );
 		if ( action == IOCTL_SWITCH ) printf( "INFO: Switching device %s to %s\n", dev, host );
 		if ( action == IOCTL_ADD_SRV ) printf( "INFO: %s: adding %s\n", dev, host );
 		if ( action == IOCTL_REM_SRV ) printf( "INFO: %s: removing %s\n", dev, host );
-		if ( dnbd3_ioctl( dev, action, &msg ) ) exit( EXIT_SUCCESS );
+		if ( dnbd3_ioctl( dev, action, &msg ) == 0 ) exit( EXIT_SUCCESS );
 		printf( "Failed! Maybe the device is not connected?\n" );
 		exit( EXIT_FAILURE );
 	}
 
 	// connect
 	if ( action == IOCTL_OPEN && msg.hosts_num > 0 && dev && (msg.imgname != NULL )) {
-		printf( "INFO: Connecting device %s to %s for image %s\n", dev, host, msg.imgname );
-		if ( dnbd3_ioctl( dev, IOCTL_OPEN, &msg ) ) exit( EXIT_SUCCESS );
-		printf( "ERROR: connecting device failed. Maybe it's already connected?\n" );
-		exit( EXIT_FAILURE );
+		printf( "INFO: Connecting device %s for image %s\n", dev, msg.imgname );
+		active_device_num = dnbd3_ioctl( dev, IOCTL_OPEN, &msg );
+		if ( active_device_num >= 0 ) {
+			host_to_string( &msg.hosts[active_device_num], host, 50 );
+			printf( "INFO: Device %s for image %s is connected to server %s\n", dev, msg.imgname, host);
+			exit( EXIT_SUCCESS );
+		} else {
+			printf( "ERROR: connecting device failed. Maybe it's already connected?\n" );
+			exit( EXIT_FAILURE );
+		}
 	}
 
 	dnbd3_print_help( argv[0] );
@@ -372,7 +378,7 @@ static int dnbd3_ioctl(const char *dev, const int command, dnbd3_ioctl_t * const
 	const int fd = open( dev, O_WRONLY );
 	if ( fd < 0 ) {
 		printf( "open() for %s failed.\n", dev );
-		return false;
+		return -ENODEV;
 	}
 	if ( msg != NULL && msg->imgname != NULL ) msg->imgnamelen = (uint16_t)strlen( msg->imgname );
 	const int ret = ioctl( fd, command, msg );
@@ -380,7 +386,7 @@ static int dnbd3_ioctl(const char *dev, const int command, dnbd3_ioctl_t * const
 		printf( "ioctl() failed.\n" );
 	}
 	close( fd );
-	return ret >= 0;
+	return ret;
 }
 
 static void dnbd3_client_daemon()
@@ -585,7 +591,7 @@ static int dnbd3_daemon_ioctl(int uid, char *device, int action, const char *act
 		printf( "%s: User %d cannot access %s owned by %d\n", actionName, uid, dev, openDevices[index] );
 		return false;
 	}
-	if ( dnbd3_ioctl( dev, action, &msg ) ) {
+	if ( dnbd3_ioctl( dev, action, &msg ) == 0 ) {
 		printf( "%s request for device %s of user %d successful\n", actionName, dev, uid );
 		openDevices[index] = -1;
 		return true;
@@ -627,7 +633,7 @@ static char* dnbd3_daemon_open(int uid, char *host, char *image, int rid, int re
 		msg.rid = rid;
 		msg.use_server_provided_alts = doLearnNewServers;
 		msg.read_ahead_kb = readAhead;
-		if ( dnbd3_ioctl( dev, IOCTL_OPEN, &msg ) ) {
+		if ( dnbd3_ioctl( dev, IOCTL_OPEN, &msg ) >= 0 ) {
 			openDevices[i] = uid;
 			printf( "Device %s now occupied by %d\n", dev, uid );
 			return dev;
diff --git a/src/kernel/blk.c b/src/kernel/blk.c
index 6e3f162..69d02d5 100644
--- a/src/kernel/blk.c
+++ b/src/kernel/blk.c
@@ -141,12 +141,12 @@ static int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int
 					result = -ENOENT;
 				} else {
 					/* probing server succeeds, abort probing of other servers */
-					result = 0;
+					result = i;
 					break;
 				}
 			}
 
-			if (result == 0)
+			if (result >= 0)
 			{
 				/* probing was successful */
 				if (dev->cur_server.host.type == HOST_IP4)
-- 
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