[Devel] Re: [PATCH 01/10] Remove devpts_root global

[Serge E. Hallyn]

Quoting sukadev at us.ibm.com (sukadev at us.ibm.com):
> 
> >From 57b3c2e5e40a63c8de630f88f6862851acb6e6c4 Mon Sep 17 00:00:00 2001
> From: Sukadev Bhattiprolu <sukadev at us.ibm.com>
> Date: Tue, 9 Sep 2008 10:21:44 -0700
> Subject: [PATCH 01/10] Remove devpts_root global
> 
> Remove the 'devpts_root' global variable and find the root dentry using
> the super_block. The super-block can be found from the device inode, using
> the new wrapper, pts_sb_from_inode().
> 
> Changelog: This patch is based on an earlier patchset from Serge Hallyn
> 	   and Matt Helsley.
> 
> Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>

Ok, I'll just have to go through these one by one until I figure out
why it's locking up my kernel...  This one absolutely looks clean.

Acked-by: Serge Hallyn <serue at us.ibm.com>

> ---
>  fs/devpts/inode.c |   29 ++++++++++++++++++++---------
>  1 files changed, 20 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
> index a70d5d0..ec33833 100644
> --- a/fs/devpts/inode.c
> +++ b/fs/devpts/inode.c
> @@ -34,7 +34,6 @@ static DEFINE_IDA(allocated_ptys);
>  static DEFINE_MUTEX(allocated_ptys_lock);
> 
>  static struct vfsmount *devpts_mnt;
> -static struct dentry *devpts_root;
> 
>  static struct {
>  	int setuid;
> @@ -56,6 +55,14 @@ static match_table_t tokens = {
>  	{Opt_err, NULL}
>  };
> 
> +static inline struct super_block *pts_sb_from_inode(struct inode *inode)
> +{
> +	if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
> +		return inode->i_sb;
> +
> +	return devpts_mnt->mnt_sb;
> +}
> +
>  static int devpts_remount(struct super_block *sb, int *flags, char *data)
>  {
>  	char *p;
> @@ -142,7 +149,7 @@ devpts_fill_super(struct super_block *s, void *data, int silent)
>  	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;
>  	
> @@ -211,7 +218,9 @@ int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
>  	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 super_block *sb = pts_sb_from_inode(ptmx_inode);
> +	struct inode *inode = new_inode(sb);
> +	struct dentry *root = sb->s_root;
>  	char s[12];
> 
>  	/* We're supposed to be given the slave end of a pty */
> @@ -231,15 +240,15 @@ int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
> 
>  	sprintf(s, "%d", number);
> 
> -	mutex_lock(&devpts_root->d_inode->i_mutex);
> +	mutex_lock(&root->d_inode->i_mutex);
> 
> -	dentry = d_alloc_name(devpts_root, s);
> +	dentry = d_alloc_name(root, s);
>  	if (!IS_ERR(dentry)) {
>  		d_add(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;
>  }
> @@ -256,11 +265,13 @@ struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
>  void devpts_pty_kill(struct tty_struct *tty)
>  {
>  	struct inode *inode = tty->driver_data;
> +	struct super_block *sb = pts_sb_from_inode(inode);
> +	struct dentry *root = sb->s_root;
>  	struct dentry *dentry;
> 
>  	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
> 
> -	mutex_lock(&devpts_root->d_inode->i_mutex);
> +	mutex_lock(&root->d_inode->i_mutex);
> 
>  	dentry = d_find_alias(inode);
>  	if (dentry && !IS_ERR(dentry)) {
> @@ -269,7 +280,7 @@ void devpts_pty_kill(struct tty_struct *tty)
>  		dput(dentry);
>  	}
> 
> -	mutex_unlock(&devpts_root->d_inode->i_mutex);
> +	mutex_unlock(&root->d_inode->i_mutex);
>  }
> 
>  static int __init init_devpts_fs(void)
> -- 
> 1.5.2.5
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