[PATCH 09/11] sysfs: add sysfs_ns_exit routine

Benjamin Thery
2008-06-06T15:50:47Z

Add sysfs routine sysfs_ns_exit() to allow a namespace to go away while
sysfs is still mounted.

The exiting namespace calls this routine and pass it a callback to be
called for every sysfs superblocks present. The callback contains the
necessary code to clean the superblock tag data associated with this
namespace.

Signed-off-by: Benjamin Thery <benjamin.thery@bull.net>
---
fs/sysfs/mount.c | 21 +++++++++++++++++++++
include/linux/sysfs.h | 8 ++++++++
2 files changed, 29 insertions(+)

Index: linux-mm/fs/sysfs/mount.c
===================================================================
--- linux-mm.orig/fs/sysfs/mount.c
+++ linux-mm/fs/sysfs/mount.c
@@ -181,6 +181,27 @@ restart:
spin_unlock(&sb_lock);
}

+/* Clean sysfs tags related to a given namespace when it exits */
+void sysfs_ns_exit(void (*func)(struct sysfs_tag_info *, void *), void *data)
+{
+ /* Allow the namespace to go away while sysfs is still mounted. */
+ struct super_block *sb;
+ mutex_lock(&sysfs_rename_mutex);
+ sysfs_grab_supers();
+ mutex_lock(&sysfs_mutex);
+ list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
+
+ struct sysfs_super_info *info = sysfs_info(sb);
+ /* Call the cleaning routine provided by the namespace.
+ * data is the current namespace id passed by the namespace.
+ */
+ func(&info->tag, data);
+ }
+ mutex_unlock(&sysfs_mutex);
+ sysfs_release_supers();
+ mutex_unlock(&sysfs_rename_mutex);
+}
+
int __init sysfs_init(void)
{
int err = -ENOMEM;
Index: linux-mm/include/linux/sysfs.h
===================================================================
--- linux-mm.orig/include/linux/sysfs.h
+++ linux-mm/include/linux/sysfs.h
@@ -134,6 +134,9 @@ void sysfs_printk_last_file(void);
int sysfs_enable_tagging(struct kobject *kobj,
const struct sysfs_tagged_dir_operations *tag_ops);

+void sysfs_ns_exit(void (*func)(struct sysfs_tag_info *, void *),
+ void *data);
+
extern int __must_check sysfs_init(void);

#else /* CONFIG_SYSFS */
@@ -247,6 +250,11 @@ static inline int sysfs_enable_tagging(s
return 0;
}

+static inline void sysfs_ns_exit(void (*func)(struct sysfs_tag_info *, void *),
+ void *data)
+{
+}
+
static inline int __must_check sysfs_init(void)
{
return 0;

--