[Devel] [PATCH RHEL7 COMMIT] ve/vtty: Make indices to match pcs6 scheme

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-229.7.2.vz7.8.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.8.8
------>
commit 77f7c920ddb6426dfb580fff5146da73c6f7f7d3
Author: Cyrill Gorcunov <gorcunov at virtuozzo.com>
Date:   Thu Oct 15 20:04:49 2015 +0400

    ve/vtty: Make indices to match pcs6 scheme
    
    In pcs6 vttys are mapped into internal kernel representation in
    nonobvious way. The /dev/console represent [maj:5,min:1], in
    turn /dev/tty[0-...] are defined as [maj:4,min:0...], where
    minor is bijective to symbol postfix of the tty. Internally
    in the pcs6 kernel any open of /dev/ttyX has been mapping
    minor into vtty index as
    
     |	if (minor > 0)
     |		index = minor - 1
     |	else
     |		index = 0
    
    which actually shifts indices and make /dev/tty0 as
    an alias to /dev/console inside container.
    
    Same time vzctl tool passes console number argument
    in a decremented way, iow when one is typing
    
    	vzctl console $ctid 1
    
    here is 1 is a tty number, the kernel sees is as 0,
    opening containers /dev/console.
    
    When one types "vzctl console $ctid 2" (which implies
    to open container's /dev/tty2) the vzctl passes index 1
    and the kernel opens /dev/tty2 because of the if/else index
    mapping as show above.
    
    Lets implement same indices mapping in pcs7 for backward
    compatibility (in pcs7 there is a per-VE vtty_map_t structure
    which reserve up to MAX_NR_VTTY_CONSOLES ttys to track
    and it is simply an array addressed by tty index).
    
    Same time lets fix a few nits: disable setup of controlling
    terminal on /dev/console only, since all ttys can have
    controlling sign; make sure we're having @tty_fops for
    such terminals.
    
    https://jira.sw.ru/browse/PSBM-40088
    
    Signed-off-by: Cyrill Gorcunov <gorcunov at virtuozzo.com>
    Reviewed-by: Vladimir Davydov <vdavydov at virtuozzo.com>
    
    CC: Konstantin Khorenko <khorenko at virtuozzo.com>
    CC: Igor Sukhih <igor at parallels.com>
    
     drivers/tty/pty.c    |    7 +++++--
     drivers/tty/tty_io.c |   12 ++++++++++--
     2 files changed, 15 insertions(+), 4 deletions(-)
---
 drivers/tty/pty.c    |  7 +++++--
 drivers/tty/tty_io.c | 12 ++++++++++--
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index b74ddca..0ab36f9 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -1240,8 +1240,11 @@ struct tty_driver *vtty_console_driver(int *index)
 struct tty_driver *vtty_driver(dev_t dev, int *index)
 {
 	if (MAJOR(dev) == TTY_MAJOR &&
-	    MINOR(dev) < MAX_NR_VTTY_CONSOLES) {
-		*index = MINOR(dev);
+	    MINOR(dev) <= MAX_NR_VTTY_CONSOLES) {
+		if (MINOR(dev))
+			*index = MINOR(dev) - 1;
+		else
+			*index = 0;
 		return vttys_driver;
 	}
 	return NULL;
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 8fc8334..8ce0a5f 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1941,7 +1941,8 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
 	if (!ve_is_super(ve)) {
 		driver = vtty_driver(device, index);
 		if (driver) {
-			*noctty = 1;
+			if (MINOR(device) == 0)
+				*noctty = 1;
 			return tty_driver_kref_get(driver);
 		}
 	}
@@ -1960,8 +1961,15 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
 	case MKDEV(TTYAUX_MAJOR, 1): {
 		struct tty_driver *console_driver = console_device(index);
 #ifdef CONFIG_VE
-		if (!ve_is_super(ve))
+		if (!ve_is_super(ve)) {
 			console_driver = vtty_console_driver(index);
+			/*
+			 * Reset fops, sometimes there might be
+			 * console_fops picked from inode->i_cdev
+			 * in chrdev_open()
+			 */
+			filp->f_op = &tty_fops;
+		}
 #endif
 		if (console_driver) {
 			driver = tty_driver_kref_get(console_driver);