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Message-ID: <20151110065126.GA20339@lst.de>
Date: Tue, 10 Nov 2015 07:51:26 +0100
From: Christoph Hellwig <hch@....de>
To: akpm@...ux-foundation.org
Cc: Daniel Baluta <daniel.baluta@...el.com>, jic23@...nel.org,
jlbec@...lplan.org, linux-iio@...r.kernel.org,
linux-fsdevel@...r.kernel.org, lars@...afoo.de, hch@....de,
knaack.h@....de, linux-kernel@...r.kernel.org,
octavian.purdila@...el.com, pebolle@...cali.nl,
patrick.porlan@...el.com, adriana.reus@...el.com,
constantin.musca@...el.com, marten@...uitiveaerial.com,
cristina.opriceana@...il.com, pmeerw@...erw.net,
viro@...iv.linux.org.uk, akpm@...ux-foundation.org
Subject: Re: [PATCH v10 1/5] configfs: Allow dynamic group creation
Andrew,
is this simple addition something you could still send on to Linus
for this merge window? I would make my life easier to have it in
so I could start using it in patches for various trees in the next
merge window.
Thanks,
Christoph
On Fri, Oct 23, 2015 at 06:33:27PM +0300, Daniel Baluta wrote:
> We don't want to hardcode default groups at subsystem
> creation time. We export:
> * configfs_register_group
> * configfs_unregister_group
> to allow drivers to programatically create/destroy groups
> later, after module init time.
>
> This is needed for IIO configfs support.
>
> Suggested-by: Lars-Peter Clausen <lars@...afoo.de>
> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
> ---
> fs/configfs/dir.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/configfs.h | 10 +++++
> 2 files changed, 120 insertions(+)
>
> diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
> index c81ce7f..a7a1b21 100644
> --- a/fs/configfs/dir.c
> +++ b/fs/configfs/dir.c
> @@ -1636,6 +1636,116 @@ const struct file_operations configfs_dir_operations = {
> .iterate = configfs_readdir,
> };
>
> +/**
> + * configfs_register_group - creates a parent-child relation between two groups
> + * @parent_group: parent group
> + * @group: child group
> + *
> + * link groups, creates dentry for the child and attaches it to the
> + * parent dentry.
> + *
> + * Return: 0 on success, negative errno code on error
> + */
> +int configfs_register_group(struct config_group *parent_group,
> + struct config_group *group)
> +{
> + struct configfs_subsystem *subsys = parent_group->cg_subsys;
> + struct dentry *parent;
> + int ret;
> +
> + mutex_lock(&subsys->su_mutex);
> + link_group(parent_group, group);
> + mutex_unlock(&subsys->su_mutex);
> +
> + parent = parent_group->cg_item.ci_dentry;
> +
> + mutex_lock_nested(&d_inode(parent)->i_mutex, I_MUTEX_PARENT);
> + ret = create_default_group(parent_group, group);
> + if (!ret) {
> + spin_lock(&configfs_dirent_lock);
> + configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
> + spin_unlock(&configfs_dirent_lock);
> + }
> + mutex_unlock(&d_inode(parent)->i_mutex);
> + return ret;
> +}
> +EXPORT_SYMBOL(configfs_register_group);
> +
> +/**
> + * configfs_unregister_group() - unregisters a child group from its parent
> + * @group: parent group to be unregistered
> + *
> + * Undoes configfs_register_group()
> + */
> +void configfs_unregister_group(struct config_group *group)
> +{
> + struct configfs_subsystem *subsys = group->cg_subsys;
> + struct dentry *dentry = group->cg_item.ci_dentry;
> + struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
> +
> + mutex_lock_nested(&d_inode(parent)->i_mutex, I_MUTEX_PARENT);
> + spin_lock(&configfs_dirent_lock);
> + configfs_detach_prep(dentry, NULL);
> + spin_unlock(&configfs_dirent_lock);
> +
> + configfs_detach_group(&group->cg_item);
> + d_inode(dentry)->i_flags |= S_DEAD;
> + dont_mount(dentry);
> + d_delete(dentry);
> + mutex_unlock(&d_inode(parent)->i_mutex);
> +
> + dput(dentry);
> +
> + mutex_lock(&subsys->su_mutex);
> + unlink_group(group);
> + mutex_unlock(&subsys->su_mutex);
> +}
> +EXPORT_SYMBOL(configfs_unregister_group);
> +
> +/**
> + * configfs_register_default_group() - allocates and registers a child group
> + * @parent_group: parent group
> + * @name: child group name
> + * @item_type: child item type description
> + *
> + * boilerplate to allocate and register a child group with its parent. We need
> + * kzalloc'ed memory because child's default_group is initially empty.
> + *
> + * Return: allocated config group or ERR_PTR() on error
> + */
> +struct config_group *
> +configfs_register_default_group(struct config_group *parent_group,
> + const char *name,
> + struct config_item_type *item_type)
> +{
> + int ret;
> + struct config_group *group;
> +
> + group = kzalloc(sizeof(*group), GFP_KERNEL);
> + if (!group)
> + return ERR_PTR(-ENOMEM);
> + config_group_init_type_name(group, name, item_type);
> +
> + ret = configfs_register_group(parent_group, group);
> + if (ret) {
> + kfree(group);
> + return ERR_PTR(ret);
> + }
> + return group;
> +}
> +EXPORT_SYMBOL(configfs_register_default_group);
> +
> +/**
> + * configfs_unregister_default_group() - unregisters and frees a child group
> + * @group: the group to act on
> + */
> +void configfs_unregister_default_group(struct config_group *group)
> +{
> + configfs_unregister_group(group);
> + kfree(group);
> +}
> +EXPORT_SYMBOL(configfs_unregister_default_group);
> +
> int configfs_register_subsystem(struct configfs_subsystem *subsys)
> {
> int err;
> diff --git a/include/linux/configfs.h b/include/linux/configfs.h
> index 63a36e8..931ca25 100644
> --- a/include/linux/configfs.h
> +++ b/include/linux/configfs.h
> @@ -252,6 +252,16 @@ static inline struct configfs_subsystem *to_configfs_subsystem(struct config_gro
> int configfs_register_subsystem(struct configfs_subsystem *subsys);
> void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
>
> +int configfs_register_group(struct config_group *parent_group,
> + struct config_group *group);
> +void configfs_unregister_group(struct config_group *group);
> +
> +struct config_group *
> +configfs_register_default_group(struct config_group *parent_group,
> + const char *name,
> + struct config_item_type *item_type);
> +void configfs_unregister_default_group(struct config_group *group);
> +
> /* These functions can sleep and can alloc with GFP_KERNEL */
> /* WARNING: These cannot be called underneath configfs callbacks!! */
> int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
> --
> 1.9.1
---end quoted text---
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