Message ID | 20100503212315.GA4141@us.ibm.com |
---|---|
State | Not Applicable, archived |
Delegated to: | David Miller |
Headers | show |
Hello, On 05/03/2010 11:23 PM, Serge E. Hallyn wrote: > (against gregkh-2.6) > > 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.) This sure is an improvement but yeah I agree that having an overall documentation would be great. If there isn't a matching one, just create one - sysfs-ns.txt, sysfs-tagged.txt or whatever. Thanks.
Quoting Tejun Heo (tj@kernel.org): > Hello, > > On 05/03/2010 11:23 PM, Serge E. Hallyn wrote: > > (against gregkh-2.6) > > > > 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.) > > This sure is an improvement but yeah I agree that having an overall > documentation would be great. If there isn't a matching one, just > create one - sysfs-ns.txt, sysfs-tagged.txt or whatever. I'll try to whip something up tonight. -serge -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff -Nrup --exclude=.pc linux.orig/fs/sysfs/dir.c linux/fs/sysfs/dir.c --- linux.orig/fs/sysfs/dir.c 2010-05-03 15:10:29.000000000 -0400 +++ linux/fs/sysfs/dir.c 2010-05-03 16:37:12.000000000 -0400 @@ -614,6 +614,14 @@ int sysfs_create_subdir(struct kobject * 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 -Nrup --exclude=.pc linux.orig/fs/sysfs/sysfs.h linux/fs/sysfs/sysfs.h --- linux.orig/fs/sysfs/sysfs.h 2010-05-03 15:10:29.000000000 -0400 +++ linux/fs/sysfs/sysfs.h 2010-05-03 16:43:06.000000000 -0400 @@ -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(st 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]; }; diff -Nrup --exclude=.pc linux.orig/include/linux/kobject.h linux/include/linux/kobject.h --- linux.orig/include/linux/kobject.h 2010-05-03 15:10:29.000000000 -0400 +++ linux/include/linux/kobject.h 2010-05-03 16:43:50.000000000 -0400 @@ -136,12 +136,23 @@ struct kobj_attribute { extern const struct sysfs_ops kobj_sysfs_ops; +/* + * Namespace types which are used to tag kobjects and sysfs entries. + * Network namespace will likely be the first. + */ enum kobj_ns_type { KOBJ_NS_TYPE_NONE = 0, KOBJ_NS_TYPES }; struct sock; + +/* + * Callbacks so sysfs can determine namespaces + * @current_ns: return calling task's namespace + * @netlink_ns: return namespace to which a sock belongs (right?) + * @initial_ns: return the initial namespace (i.e. init_net_ns) + */ struct kobj_ns_type_operations { enum kobj_ns_type type; const void *(*current_ns)(void); diff -Nrup --exclude=.pc linux.orig/include/linux/sysfs.h linux/include/linux/sysfs.h --- linux.orig/include/linux/sysfs.h 2010-05-03 15:10:29.000000000 -0400 +++ linux/include/linux/sysfs.h 2010-05-03 15:51:41.000000000 -0400 @@ -178,6 +178,7 @@ struct sysfs_dirent *sysfs_get(struct sy void sysfs_put(struct sysfs_dirent *sd); void sysfs_printk_last_file(void); +/* Called to clear a ns tag when it is no longer valid */ void sysfs_exit_ns(enum kobj_ns_type type, const void *tag); int __must_check sysfs_init(void); diff -Nrup --exclude=.pc linux.orig/lib/kobject.c linux/lib/kobject.c --- linux.orig/lib/kobject.c 2010-05-03 15:10:29.000000000 -0400 +++ linux/lib/kobject.c 2010-05-03 16:47:01.000000000 -0400 @@ -948,6 +948,17 @@ const void *kobj_ns_initial(enum kobj_ns return ns; } +/* + * kobj_ns_exit - invalidate a namespace tag + * + * @type: the namespace type (i.e. KOBJ_NS_TYPE_NET) + * @ns: the actual namespace being invalidated + * + * This is called when a tag is no longer valid. For instance, + * when a network namespace exits, it uses this helper to + * make sure no sb's sysfs_info points to the now-invalidated + * netns. + */ void kobj_ns_exit(enum kobj_ns_type type, const void *ns) { sysfs_exit_ns(type, ns);
(against gregkh-2.6) 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 <serue@us.ibm.com> --- fs/sysfs/dir.c | 8 ++++++++ fs/sysfs/sysfs.h | 13 ++++++++++++- include/linux/kobject.h | 11 +++++++++++ include/linux/sysfs.h | 1 + lib/kobject.c | 11 +++++++++++ 5 files changed, 43 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html