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SubjectRe: [PATCH] fs/configfs: allow to create groups on demand
On Thu, Nov 29, 2012 at 05:41:23PM +0100, Sebastian Andrzej Siewior wrote:
> This patch adds a function add a group to an existing one and its
> counterart. The newly created group behaves as it would be created via
> default_groups[] which means the user can't rmdir it.
> This should be used by the upcomming USB gadget interface in order to
> add the currently available UDCs as a child of the UDC node. The UDC
> itself will appear once the hardware driver is loaded and can appear
> later.

I've now responded to the original thread. Sorry I didn't notice last
week. Please see my thoughts there and comment.

Joel

>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> fs/configfs/dir.c | 63 ++++++++++++++++++++++++++++++++++------------
> include/linux/configfs.h | 4 +++
> 2 files changed, 51 insertions(+), 16 deletions(-)
>
> diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
> index 7414ae2..50ee2bd 100644
> --- a/fs/configfs/dir.c
> +++ b/fs/configfs/dir.c
> @@ -1663,19 +1663,13 @@ const struct file_operations configfs_dir_operations = {
> .readdir = configfs_readdir,
> };
>
> -int configfs_register_subsystem(struct configfs_subsystem *subsys)
> +static int __create_group(struct config_group *group, struct dentry *root)
> {
> int err;
> - struct config_group *group = &subsys->su_group;
> struct qstr name;
> struct dentry *dentry;
> - struct dentry *root;
> struct configfs_dirent *sd;
>
> - root = configfs_pin_fs();
> - if (IS_ERR(root))
> - return PTR_ERR(root);
> -
> if (!group->cg_item.ci_name)
> group->cg_item.ci_name = group->cg_item.ci_namebuf;
>
> @@ -1708,25 +1702,48 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
>
> mutex_unlock(&root->d_inode->i_mutex);
>
> - if (err) {
> + if (err)
> unlink_group(group);
> - configfs_release_fs();
> +
> + return err;
> +}
> +
> +int configfs_create_group(struct config_group *parent, struct config_group *new)
> +{
> + int ret;
> +
> + ret = __create_group(new, parent->cg_item.ci_dentry);
> + if (!ret) {
> + struct configfs_dirent *sd = new->cg_item.ci_dentry->d_fsdata;
> +
> + sd->s_type |= CONFIGFS_USET_DEFAULT;
> }
>
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(configfs_create_group);
> +
> +int configfs_register_subsystem(struct configfs_subsystem *subsys)
> +{
> + int err;
> + struct dentry *root;
> +
> + root = configfs_pin_fs();
> + if (IS_ERR(root))
> + return PTR_ERR(root);
> +
> + err = __create_group(&subsys->su_group, root);
> + if (err)
> + configfs_release_fs();
> +
> return err;
> }
>
> -void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
> +void configfs_remove_group(struct config_group *group)
> {
> - struct config_group *group = &subsys->su_group;
> struct dentry *dentry = group->cg_item.ci_dentry;
> struct dentry *root = dentry->d_sb->s_root;
>
> - if (dentry->d_parent != root) {
> - printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
> - return;
> - }
> -
> mutex_lock_nested(&root->d_inode->i_mutex,
> I_MUTEX_PARENT);
> mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
> @@ -1749,6 +1766,20 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
> dput(dentry);
>
> unlink_group(group);
> +}
> +EXPORT_SYMBOL_GPL(configfs_remove_group);
> +
> +void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
> +{
> + struct config_group *group = &subsys->su_group;
> + struct dentry *dentry = group->cg_item.ci_dentry;
> + struct dentry *root = dentry->d_sb->s_root;
> +
> + if (dentry->d_parent != root) {
> + pr_err("configfs: Tried to unregister non-subsystem!\n");
> + return;
> + }
> + configfs_remove_group(group);
> configfs_release_fs();
> }
>
> diff --git a/include/linux/configfs.h b/include/linux/configfs.h
> index 34025df..660c25d 100644
> --- a/include/linux/configfs.h
> +++ b/include/linux/configfs.h
> @@ -249,6 +249,10 @@ static inline struct configfs_subsystem *to_configfs_subsystem(struct config_gro
> NULL;
> }
>
> +int configfs_create_group(struct config_group *parent,
> + struct config_group *new);
> +void configfs_remove_group(struct config_group *group);
> +
> int configfs_register_subsystem(struct configfs_subsystem *subsys);
> void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
>
> --
> 1.7.10.4
>
> --
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--

"Friends may come and go, but enemies accumulate."
- Thomas Jones

http://www.jlbec.org/
jlbec@evilplan.org


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