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Message-ID: <20080412173327.GC19449@us.ibm.com>
Date: Sat, 12 Apr 2008 10:33:27 -0700
From: sukadev@...ibm.com
To: Andrew Morton <akpm@...l.org>
Cc: serue@...ibm.com, matthltc@...ibm.com,
"Eric W. Biederman" <ebiederm@...ssion.com>, hpa@...or.com,
Pavel Emelyanov <xemul@...nvz.org>,
Containers <containers@...ts.osdl.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH 3/4]: Move devpts globals into init_pts_ns
Matt, Serge, please sign-off on this version.
---
From: Sukadev Bhattiprolu <sukadev@...ibm.com>
Subject: [PATCH 3/4]: Move devpts globals into init_pts_ns
Move devpts global variables 'allocated_ptys' and 'devpts_mnt' into a new
'pts_namespace' and remove the 'devpts_root'.
Changelog:
- Split these relatively simpler changes off from the patch that
supports remounting devpts.
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ibm.com>
---
fs/devpts/inode.c | 84 ++++++++++++++++++++++++++++++++--------------
include/linux/devpts_fs.h | 10 +++++
2 files changed, 70 insertions(+), 24 deletions(-)
Index: 2.6.25-rc8-mm1/fs/devpts/inode.c
===================================================================
--- 2.6.25-rc8-mm1.orig/fs/devpts/inode.c 2008-04-11 10:12:09.000000000 -0700
+++ 2.6.25-rc8-mm1/fs/devpts/inode.c 2008-04-12 10:10:33.000000000 -0700
@@ -28,12 +28,8 @@
#define DEVPTS_DEFAULT_MODE 0600
extern int pty_limit; /* Config limit on Unix98 ptys */
-static DEFINE_IDR(allocated_ptys);
static DECLARE_MUTEX(allocated_ptys_lock);
-static struct vfsmount *devpts_mnt;
-static struct dentry *devpts_root;
-
static struct {
int setuid;
int setgid;
@@ -54,6 +50,14 @@ static match_table_t tokens = {
{Opt_err, NULL}
};
+struct pts_namespace init_pts_ns = {
+ .kref = {
+ .refcount = ATOMIC_INIT(2),
+ },
+ .allocated_ptys = IDR_INIT(init_pts_ns.allocated_ptys),
+ .mnt = NULL,
+};
+
static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
char *p;
@@ -140,7 +144,7 @@ devpts_fill_super(struct super_block *s,
inode->i_fop = &simple_dir_operations;
inode->i_nlink = 2;
- devpts_root = s->s_root = d_alloc_root(inode);
+ s->s_root = d_alloc_root(inode);
if (s->s_root)
return 0;
@@ -168,10 +172,9 @@ static struct file_system_type devpts_fs
* to the System V naming convention
*/
-static struct dentry *get_node(int num)
+static struct dentry *get_node(struct dentry *root, int num)
{
char s[12];
- struct dentry *root = devpts_root;
mutex_lock(&root->d_inode->i_mutex);
return lookup_one_len(s, root, sprintf(s, "%d", num));
}
@@ -180,14 +183,17 @@ int devpts_new_index(void)
{
int index;
int idr_ret;
+ struct pts_namespace *pts_ns;
+
+ pts_ns = &init_pts_ns;
retry:
- if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
+ if (!idr_pre_get(&pts_ns->allocated_ptys, GFP_KERNEL)) {
return -ENOMEM;
}
down(&allocated_ptys_lock);
- idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
+ idr_ret = idr_get_new(&pts_ns->allocated_ptys, NULL, &index);
if (idr_ret < 0) {
up(&allocated_ptys_lock);
if (idr_ret == -EAGAIN)
@@ -196,7 +202,7 @@ retry:
}
if (index >= pty_limit) {
- idr_remove(&allocated_ptys, index);
+ idr_remove(&pts_ns->allocated_ptys, index);
up(&allocated_ptys_lock);
return -EIO;
}
@@ -206,8 +212,10 @@ retry:
void devpts_kill_index(int idx)
{
+ struct pts_namespace *pts_ns = &init_pts_ns;
+
down(&allocated_ptys_lock);
- idr_remove(&allocated_ptys, idx);
+ idr_remove(&pts_ns->allocated_ptys, idx);
up(&allocated_ptys_lock);
}
@@ -217,12 +225,26 @@ int devpts_pty_new(struct tty_struct *tt
struct tty_driver *driver = tty->driver;
dev_t device = MKDEV(driver->major, driver->minor_start+number);
struct dentry *dentry;
- struct inode *inode = new_inode(devpts_mnt->mnt_sb);
+ struct dentry *root;
+ struct inode *inode;
+ struct pts_namespace *pts_ns;
/* We're supposed to be given the slave end of a pty */
BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
+ pts_ns = &init_pts_ns;
+ root = pts_ns->mnt->mnt_root;
+
+ mutex_lock(&root->d_inode->i_mutex);
+ inode = idr_find(&pts_ns->allocated_ptys, number);
+ mutex_unlock(&root->d_inode->i_mutex);
+
+ if (inode && !IS_ERR(inode))
+ return -EEXIST;
+
+ inode = new_inode(pts_ns->mnt->mnt_sb);
+
if (!inode)
return -ENOMEM;
@@ -232,23 +254,28 @@ int devpts_pty_new(struct tty_struct *tt
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
init_special_inode(inode, S_IFCHR|config.mode, device);
inode->i_private = tty;
+ idr_replace(&pts_ns->allocated_ptys, inode, number);
- dentry = get_node(number);
+ dentry = get_node(root, number);
if (!IS_ERR(dentry) && !dentry->d_inode) {
d_instantiate(dentry, inode);
- fsnotify_create(devpts_root->d_inode, dentry);
+ fsnotify_create(root->d_inode, dentry);
}
- mutex_unlock(&devpts_root->d_inode->i_mutex);
+ mutex_unlock(&root->d_inode->i_mutex);
return 0;
}
struct tty_struct *devpts_get_tty(int number)
{
- struct dentry *dentry = get_node(number);
+ struct dentry *root;
+ struct dentry *dentry;
struct tty_struct *tty;
+ root = init_pts_ns.mnt->mnt_root;
+ dentry = get_node(root, number);
+
tty = NULL;
if (!IS_ERR(dentry)) {
if (dentry->d_inode)
@@ -256,14 +283,18 @@ struct tty_struct *devpts_get_tty(int nu
dput(dentry);
}
- mutex_unlock(&devpts_root->d_inode->i_mutex);
+ mutex_unlock(&root->d_inode->i_mutex);
return tty;
}
void devpts_pty_kill(int number)
{
- struct dentry *dentry = get_node(number);
+ struct dentry *root;
+ struct dentry *dentry;
+
+ root = init_pts_ns.mnt->mnt_root;
+ dentry = get_node(root, number);
if (!IS_ERR(dentry)) {
struct inode *inode = dentry->d_inode;
@@ -274,16 +305,21 @@ void devpts_pty_kill(int number)
}
dput(dentry);
}
- mutex_unlock(&devpts_root->d_inode->i_mutex);
+ mutex_unlock(&root->d_inode->i_mutex);
}
static int __init init_devpts_fs(void)
{
- int err = register_filesystem(&devpts_fs_type);
+ struct vfsmount *mnt;
+ int err;
+
+ err = register_filesystem(&devpts_fs_type);
if (!err) {
- devpts_mnt = kern_mount(&devpts_fs_type);
- if (IS_ERR(devpts_mnt))
- err = PTR_ERR(devpts_mnt);
+ mnt = kern_mount(&devpts_fs_type);
+ if (IS_ERR(mnt))
+ err = PTR_ERR(mnt);
+ else
+ init_pts_ns.mnt = mnt;
}
return err;
}
@@ -291,7 +327,7 @@ static int __init init_devpts_fs(void)
static void __exit exit_devpts_fs(void)
{
unregister_filesystem(&devpts_fs_type);
- mntput(devpts_mnt);
+ mntput(init_pts_ns.mnt);
}
module_init(init_devpts_fs)
Index: 2.6.25-rc8-mm1/include/linux/devpts_fs.h
===================================================================
--- 2.6.25-rc8-mm1.orig/include/linux/devpts_fs.h 2008-04-11 10:34:16.000000000 -0700
+++ 2.6.25-rc8-mm1/include/linux/devpts_fs.h 2008-04-12 08:52:57.000000000 -0700
@@ -14,6 +14,16 @@
#define _LINUX_DEVPTS_FS_H
#include <linux/errno.h>
+#include <linux/kref.h>
+#include <linux/idr.h>
+
+struct pts_namespace {
+ struct kref kref;
+ struct idr allocated_ptys;
+ struct vfsmount *mnt;
+};
+
+extern struct pts_namespace init_pts_ns;
#ifdef CONFIG_UNIX98_PTYS
--
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