[PATCH 08/75] Remove devpts_root global

Alan Cox
2009-01-02T13:40:57Z

From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>

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@linux.vnet.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.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 5d61b7c..f96e10a 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 const 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)