Commit b4a76faf authored by Al Viro's avatar Al Viro
Browse files

convert devpts 



Two kinds of objects there - ptmx and everything else (pty).  The former is
created on mount and kept until the fs shutdown; the latter get created
and removed by tty layer (the references are borrowed into tty->driver_data).
The reference to ptmx dentry is also kept, but we only ever use it to
find ptmx inode on remount.

* turn d_add() into d_make_persistent() + dput()  both in mknod_ptmx() and
in devpts_pty_new().

* turn dput() to d_make_discardable() in devpts_pty_kill().

* switch mknod_ptmx() to simple_{start,done}_creating().

* instead of storing in pts_fs_info a reference to ptmx dentry, store a reference
to its inode, seeing that this is what we use it for.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b8343156

fs/devpts/inode.c

+21 −36
Original line number Diff line number Diff line
@@ -102,7 +102,7 @@ struct pts_fs_info { 
	struct ida allocated_ptys;

	struct pts_mount_opts mount_opts;

	struct super_block *sb;

	struct dentry *ptmx_dentry;

	struct inode *ptmx_inode; // borrowed

};



static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
@@ -259,7 +259,6 @@ static int devpts_parse_param(struct fs_context *fc, struct fs_parameter *param) 
static int mknod_ptmx(struct super_block *sb, struct fs_context *fc)

{

	int mode;

	int rc = -ENOMEM;

	struct dentry *dentry;

	struct inode *inode;

	struct dentry *root = sb->s_root;
@@ -268,18 +267,10 @@ static int mknod_ptmx(struct super_block *sb, struct fs_context *fc) 
	kuid_t ptmx_uid = current_fsuid();

	kgid_t ptmx_gid = current_fsgid();



	inode_lock(d_inode(root));



	/* If we have already created ptmx node, return */

	if (fsi->ptmx_dentry) {

		rc = 0;

		goto out;

	}



	dentry = d_alloc_name(root, "ptmx");

	if (!dentry) {

	dentry = simple_start_creating(root, "ptmx");

	if (IS_ERR(dentry)) {

		pr_err("Unable to alloc dentry for ptmx node\n");

		goto out;

		return PTR_ERR(dentry);

	}



	/*
@@ -287,9 +278,9 @@ static int mknod_ptmx(struct super_block *sb, struct fs_context *fc) 
	 */

	inode = new_inode(sb);

	if (!inode) {

		simple_done_creating(dentry);

		pr_err("Unable to alloc inode for ptmx node\n");

		dput(dentry);

		goto out;

		return -ENOMEM;

	}



	inode->i_ino = 2;
@@ -299,23 +290,18 @@ static int mknod_ptmx(struct super_block *sb, struct fs_context *fc) 
	init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));

	inode->i_uid = ptmx_uid;

	inode->i_gid = ptmx_gid;

	fsi->ptmx_inode = inode;



	d_add(dentry, inode);

	d_make_persistent(dentry, inode);



	fsi->ptmx_dentry = dentry;

	rc = 0;

out:

	inode_unlock(d_inode(root));

	return rc;

	simple_done_creating(dentry);



	return 0;

}



static void update_ptmx_mode(struct pts_fs_info *fsi)

{

	struct inode *inode;

	if (fsi->ptmx_dentry) {

		inode = d_inode(fsi->ptmx_dentry);

		inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;

	}

	fsi->ptmx_inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;

}



static int devpts_reconfigure(struct fs_context *fc)
@@ -461,7 +447,7 @@ static void devpts_kill_sb(struct super_block *sb) 
	if (fsi)

		ida_destroy(&fsi->allocated_ptys);

	kfree(fsi);

	kill_litter_super(sb);

	kill_anon_super(sb);

}



static struct file_system_type devpts_fs_type = {
@@ -534,16 +520,15 @@ struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv) 
	sprintf(s, "%d", index);



	dentry = d_alloc_name(root, s);

	if (dentry) {

		dentry->d_fsdata = priv;

		d_add(dentry, inode);

		fsnotify_create(d_inode(root), dentry);

	} else {

	if (!dentry) {

		iput(inode);

		dentry = ERR_PTR(-ENOMEM);

		return ERR_PTR(-ENOMEM);

	}



	return dentry;

	dentry->d_fsdata = priv;

	d_make_persistent(dentry, inode);

	fsnotify_create(d_inode(root), dentry);

	dput(dentry);

	return dentry; // borrowed

}



/**
@@ -573,7 +558,7 @@ void devpts_pty_kill(struct dentry *dentry) 
	drop_nlink(dentry->d_inode);

	d_drop(dentry);

	fsnotify_unlink(d_inode(dentry->d_parent), dentry);

	dput(dentry);	/* d_alloc_name() in devpts_pty_new() */

	d_make_discardable(dentry);

}



static int __init init_devpts_fs(void)