1 files changed, 46 insertions, 56 deletions

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 1f107fd51328..0b2954d7172d 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -128,6 +128,7 @@ static const match_table_t tokens = {
 struct pts_fs_info {
 	struct ida allocated_ptys;
 	struct pts_mount_opts mount_opts;
+	struct super_block *sb;
 	struct dentry *ptmx_dentry;
 };
 
@@ -358,7 +359,7 @@ static const struct super_operations devpts_sops = {
 	.show_options	= devpts_show_options,
 };
 
-static void *new_pts_fs_info(void)
+static void *new_pts_fs_info(struct super_block *sb)
 {
 	struct pts_fs_info *fsi;
 
@@ -369,6 +370,7 @@ static void *new_pts_fs_info(void)
 	ida_init(&fsi->allocated_ptys);
 	fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE;
 	fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
+	fsi->sb = sb;
 
 	return fsi;
 }
@@ -384,7 +386,7 @@ devpts_fill_super(struct super_block *s, void *data, int silent)
 	s->s_op = &devpts_sops;
 	s->s_time_gran = 1;
 
-	s->s_fs_info = new_pts_fs_info();
+	s->s_fs_info = new_pts_fs_info(s);
 	if (!s->s_fs_info)
 		goto fail;
 
@@ -524,17 +526,14 @@ static struct file_system_type devpts_fs_type = {
  * to the System V naming convention
  */
 
-int devpts_new_index(struct inode *ptmx_inode)
+int devpts_new_index(struct pts_fs_info *fsi)
 {
-	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
-	struct pts_fs_info *fsi;
 	int index;
 	int ida_ret;
 
-	if (!sb)
+	if (!fsi)
 		return -ENODEV;
 
-	fsi = DEVPTS_SB(sb);
 retry:
 	if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
 		return -ENOMEM;
@@ -564,17 +563,38 @@ retry:
 	return index;
 }
 
-void devpts_kill_index(struct inode *ptmx_inode, int idx)
+void devpts_kill_index(struct pts_fs_info *fsi, int idx)
 {
-	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
-	struct pts_fs_info *fsi = DEVPTS_SB(sb);
-
 	mutex_lock(&allocated_ptys_lock);
 	ida_remove(&fsi->allocated_ptys, idx);
 	pty_count--;
 	mutex_unlock(&allocated_ptys_lock);
 }
 
+/*
+ * pty code needs to hold extra references in case of last /dev/tty close
+ */
+struct pts_fs_info *devpts_get_ref(struct inode *ptmx_inode, struct file *file)
+{
+	struct super_block *sb;
+	struct pts_fs_info *fsi;
+
+	sb = pts_sb_from_inode(ptmx_inode);
+	if (!sb)
+		return NULL;
+	fsi = DEVPTS_SB(sb);
+	if (!fsi)
+		return NULL;
+
+	atomic_inc(&sb->s_active);
+	return fsi;
+}
+
+void devpts_put_ref(struct pts_fs_info *fsi)
+{
+	deactivate_super(fsi->sb);
+}
+
 /**
  * devpts_pty_new -- create a new inode in /dev/pts/
  * @ptmx_inode: inode of the master
@@ -584,22 +604,20 @@ void devpts_kill_index(struct inode *ptmx_inode, int idx)
  *
  * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill.
  */
-struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
-		void *priv)
+struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv)
 {
 	struct dentry *dentry;
-	struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+	struct super_block *sb;
 	struct inode *inode;
 	struct dentry *root;
-	struct pts_fs_info *fsi;
 	struct pts_mount_opts *opts;
 	char s[12];
 
-	if (!sb)
+	if (!fsi)
 		return ERR_PTR(-ENODEV);
 
+	sb = fsi->sb;
 	root = sb->s_root;
-	fsi = DEVPTS_SB(sb);
 	opts = &fsi->mount_opts;
 
 	inode = new_inode(sb);
@@ -610,25 +628,21 @@ struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
 	inode->i_uid = opts->setuid ? opts->uid : current_fsuid();
 	inode->i_gid = opts->setgid ? opts->gid : current_fsgid();
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
-	init_special_inode(inode, S_IFCHR|opts->mode, device);
-	inode->i_private = priv;
+	init_special_inode(inode, S_IFCHR|opts->mode, MKDEV(UNIX98_PTY_SLAVE_MAJOR, index));
 
 	sprintf(s, "%d", index);
 
-	inode_lock(d_inode(root));
-
 	dentry = d_alloc_name(root, s);
 	if (dentry) {
+		dentry->d_fsdata = priv;
 		d_add(dentry, inode);
 		fsnotify_create(d_inode(root), dentry);
 	} else {
 		iput(inode);
-		inode = ERR_PTR(-ENOMEM);
+		dentry = ERR_PTR(-ENOMEM);
 	}
 
-	inode_unlock(d_inode(root));
-
-	return inode;
+	return dentry;
 }
 
 /**
@@ -637,24 +651,10 @@ struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
  *
  * Returns whatever was passed as priv in devpts_pty_new for a given inode.
  */
-void *devpts_get_priv(struct inode *pts_inode)
+void *devpts_get_priv(struct dentry *dentry)
 {
-	struct dentry *dentry;
-	void *priv = NULL;
-
-	BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
-
-	/* Ensure dentry has not been deleted by devpts_pty_kill() */
-	dentry = d_find_alias(pts_inode);
-	if (!dentry)
-		return NULL;
-
-	if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
-		priv = pts_inode->i_private;
-
-	dput(dentry);
-
-	return priv;
+	WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC);
+	return dentry->d_fsdata;
 }
 
 /**
@@ -663,24 +663,14 @@ void *devpts_get_priv(struct inode *pts_inode)
  *
  * This is an inverse operation of devpts_pty_new.
  */
-void devpts_pty_kill(struct inode *inode)
+void devpts_pty_kill(struct dentry *dentry)
 {
-	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));
+	WARN_ON_ONCE(dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC);
 
-	inode_lock(d_inode(root));
-
-	dentry = d_find_alias(inode);
-
-	drop_nlink(inode);
+	dentry->d_fsdata = NULL;
+	drop_nlink(dentry->d_inode);
 	d_delete(dentry);
 	dput(dentry);	/* d_alloc_name() in devpts_pty_new() */
-	dput(dentry);		/* d_find_alias above */
-
-	inode_unlock(d_inode(root));
 }
 
 static int __init init_devpts_fs(void)