Unverified Commit cb0e0a8b authored by Eric Sandeen's avatar Eric Sandeen Committed by Christian Brauner
Browse files

devtmpfs: replace ->mount with ->get_tree in public instance 



To finalize mount API conversion, remove the ->mount op from the public
instance in favor of ->get_tree etc. Copy most ops from the underlying
ops vector (whether it's shmem or ramfs) and substitute our own
->get_tree which simply takes an extra reference on the existing internal
mount as before.

Thanks to Al for the fs_context_for_reconfigure() idea.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Link: https://lore.kernel.org/r/20250205213931.74614-4-sandeen@redhat.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent cc0876f8

drivers/base/devtmpfs.c

+64 −17
Original line number Diff line number Diff line
@@ -63,22 +63,6 @@ __setup("devtmpfs.mount=", mount_param); 


static struct vfsmount *mnt;



static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,

		      const char *dev_name, void *data)

{

	struct super_block *s = mnt->mnt_sb;

	int err;



	atomic_inc(&s->s_active);

	down_write(&s->s_umount);

	err = reconfigure_single(s, flags, data);

	if (err < 0) {

		deactivate_locked_super(s);

		return ERR_PTR(err);

	}

	return dget(s->s_root);

}



static struct file_system_type internal_fs_type = {

	.name = "devtmpfs",

#ifdef CONFIG_TMPFS
@@ -89,9 +73,40 @@ static struct file_system_type internal_fs_type = { 
	.kill_sb = kill_litter_super,

};



/* Simply take a ref on the existing mount */

static int devtmpfs_get_tree(struct fs_context *fc)

{

	struct super_block *sb = mnt->mnt_sb;



	atomic_inc(&sb->s_active);

	down_write(&sb->s_umount);

	fc->root = dget(sb->s_root);

	return 0;

}



/* Ops are filled in during init depending on underlying shmem or ramfs type */

struct fs_context_operations devtmpfs_context_ops = {};



/* Call the underlying initialization and set to our ops */

static int devtmpfs_init_fs_context(struct fs_context *fc)

{

	int ret;

#ifdef CONFIG_TMPFS

	ret = shmem_init_fs_context(fc);

#else

	ret = ramfs_init_fs_context(fc);

#endif

	if (ret < 0)

		return ret;



	fc->ops = &devtmpfs_context_ops;



	return 0;

}



static struct file_system_type dev_fs_type = {

	.name = "devtmpfs",

	.mount = public_dev_mount,

	.init_fs_context = devtmpfs_init_fs_context,

};



static int devtmpfs_submit_req(struct req *req, const char *tmp)
@@ -442,6 +457,31 @@ static int __ref devtmpfsd(void *p) 
	return 0;

}



/*

 * Get the underlying (shmem/ramfs) context ops to build ours

 */

static int devtmpfs_configure_context(void)

{

	struct fs_context *fc;



	fc = fs_context_for_reconfigure(mnt->mnt_root, mnt->mnt_sb->s_flags,

					MS_RMT_MASK);

	if (IS_ERR(fc))

		return PTR_ERR(fc);



	/* Set up devtmpfs_context_ops based on underlying type */

	devtmpfs_context_ops.free	      = fc->ops->free;

	devtmpfs_context_ops.dup	      = fc->ops->dup;

	devtmpfs_context_ops.parse_param      = fc->ops->parse_param;

	devtmpfs_context_ops.parse_monolithic = fc->ops->parse_monolithic;

	devtmpfs_context_ops.get_tree	      = &devtmpfs_get_tree;

	devtmpfs_context_ops.reconfigure      = fc->ops->reconfigure;



	put_fs_context(fc);



	return 0;

}



/*

 * Create devtmpfs instance, driver-core devices will add their device

 * nodes here.
@@ -456,6 +496,13 @@ int __init devtmpfs_init(void) 
		pr_err("unable to create devtmpfs %ld\n", PTR_ERR(mnt));

		return PTR_ERR(mnt);

	}



	err = devtmpfs_configure_context();

	if (err) {

		pr_err("unable to configure devtmpfs type %d\n", err);

		return err;

	}



	err = register_filesystem(&dev_fs_type);

	if (err) {

		pr_err("unable to register devtmpfs type %d\n", err);