From ba7443bc656e5236c316b2acacc8b551f872910f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 28 Nov 2013 14:54:40 -0500 Subject: sysfs, kernfs: implement kernfs_create/destroy_root() There currently is single kernfs hierarchy in the whole system which is used for sysfs. kernfs needs to support multiple hierarchies to allow other users. This patch introduces struct kernfs_root which serves as the root of each kernfs hierarchy and implements kernfs_create/destroy_root(). * Each kernfs_root is associated with a root sd (sysfs_dentry). The root is freed when the root sd is released and kernfs_destory_root() simply invokes kernfs_remove() on the root sd. sysfs_remove_one() is updated to handle release of the root sd. Note that ps_iattr update in sysfs_remove_one() is trivially updated for readability. * Root sd's are now dynamically allocated using sysfs_new_dirent(). Update sysfs_alloc_ino() so that it gives out ino from 1 so that the root sd still gets ino 1. * While kernfs currently only points to the root sd, it'll soon grow fields which are specific to each hierarchy. As determining a given sd's root will be necessary, sd->s_dir.root is added. This backlink fits better as a separate field in sd; however, sd->s_dir is inside union with space to spare, so use it to save space and provide kernfs_root() accessor to determine the root sd. * As hierarchies may be destroyed now, each mount needs to hold onto the hierarchy it's attached to. Update sysfs_fill_super() and sysfs_kill_sb() so that they get and put the kernfs_root respectively. * sysfs_root is replaced with kernfs_root which is dynamically created by invoking kernfs_create_root() from sysfs_init(). This patch doesn't introduce any visible behavior changes. v2: kernfs_create_root() forgot to set @sd->priv. Fixed. Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- include/linux/kernfs.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/linux/kernfs.h') diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index fd8f574ef2fe..f75548b8ed7a 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -20,6 +20,11 @@ struct vm_area_struct; struct sysfs_dirent; +struct kernfs_root { + /* published fields */ + struct sysfs_dirent *sd; +}; + struct sysfs_open_file { /* published fields */ struct sysfs_dirent *sd; @@ -76,6 +81,9 @@ struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent, void kernfs_get(struct sysfs_dirent *sd); void kernfs_put(struct sysfs_dirent *sd); +struct kernfs_root *kernfs_create_root(void *priv); +void kernfs_destroy_root(struct kernfs_root *root); + struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv, const void *ns); @@ -107,6 +115,11 @@ kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name, static inline void kernfs_get(struct sysfs_dirent *sd) { } static inline void kernfs_put(struct sysfs_dirent *sd) { } +static inline struct kernfs_root *kernfs_create_root(void *priv) +{ return ERR_PTR(-ENOSYS); } + +static inline void kernfs_destroy_root(struct kernfs_root *root) { } + static inline struct sysfs_dirent * kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv, const void *ns) -- cgit v1.2.2