Quoting sukadev@xxxxxxxxxx (sukadev@xxxxxxxxxx):
>
> >From 57b3c2e5e40a63c8de630f88f6862851acb6e6c4 Mon Sep 17 00:00:00 2001
> From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx>
> 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@xxxxxxxxxx>
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@xxxxxxxxxx>
> ---
> 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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