From be867b194a3ae3c680c29521287ae49b4d44d420 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Mon, 3 May 2010 16:23:15 -0500 Subject: sysfs: Comment sysfs directory tagging logic Add some in-line comments to explain the new infrastructure, which was introduced to support sysfs directory tagging with namespaces. I think an overall description someplace might be good too, but it didn't really seem to fit into Documentation/filesystems/sysfs.txt, which appears more geared toward users, rather than maintainers, of sysfs. (Tejun, please let me know if I can make anything clearer or failed altogether to comment something that should be commented.) Signed-off-by: Serge E. Hallyn Cc: Eric W. Biederman Cc: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/dir.c | 8 ++++++++ fs/sysfs/sysfs.h | 13 ++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-) (limited to 'fs/sysfs') diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index a63eb4ba7867..7e54bac8c4b0 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -614,6 +614,14 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name, KOBJ_NS_TYPE_NONE, NULL, name, p_sd); } +/** + * sysfs_read_ns_type: return associated ns_type + * @kobj: the kobject being queried + * + * Each kobject can be tagged with exactly one namespace type + * (i.e. network or user). Return the ns_type associated with + * this object if any + */ static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj) { const struct kobj_ns_type_operations *ops; diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index 93847d54c2e3..6a13105b5594 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -58,7 +58,7 @@ struct sysfs_dirent { struct sysfs_dirent *s_sibling; const char *s_name; - const void *s_ns; + const void *s_ns; /* namespace tag */ union { struct sysfs_elem_dir s_dir; struct sysfs_elem_symlink s_symlink; @@ -82,6 +82,7 @@ struct sysfs_dirent { #define SYSFS_COPY_NAME (SYSFS_DIR | SYSFS_KOBJ_LINK) #define SYSFS_ACTIVE_REF (SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR) +/* identify any namespace tag on sysfs_dirents */ #define SYSFS_NS_TYPE_MASK 0xff00 #define SYSFS_NS_TYPE_SHIFT 8 @@ -93,6 +94,10 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd) return sd->s_flags & SYSFS_TYPE_MASK; } +/* + * Return any namespace tags on this dirent. + * enum kobj_ns_type is defined in linux/kobject.h + */ static inline enum kobj_ns_type sysfs_ns_type(struct sysfs_dirent *sd) { return (sd->s_flags & SYSFS_NS_TYPE_MASK) >> SYSFS_NS_TYPE_SHIFT; @@ -123,6 +128,12 @@ struct sysfs_addrm_cxt { /* * mount.c */ + +/* + * Each sb is associated with a set of namespace tags (i.e. + * the network namespace of the task which mounted this sysfs + * instance). + */ struct sysfs_super_info { const void *ns[KOBJ_NS_TYPES]; }; -- cgit v1.2.3