From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
This automatically creates the /sys/fs/<fs-type>/<s_id>
It is not necessary to use super_block_attribute structures.
Filesystems can build their own attribute structs. These are just
helper functions if a filesystem chooses to use a simple way to
show it's variables in sysfs.
Also, the SB_ATTR and SB_ATTR_RO helpers to build the
super_block_attribute.
We can use the kobject to (delay) destroy the super block.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/super.c | 57 +++++++++++++++++++++++++++++++++++++++++++++---------
include/linux/fs.h | 26 +++++++++++++++++++++++--
2 files changed, 72 insertions(+), 11 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 74914b1..5f5e25d 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -135,10 +135,36 @@ static unsigned long super_cache_count(struct shrinker *shrink,
return total_objects;
}
-static void destroy_super_work(struct work_struct *work)
+/* kobject super_block handling */
+
+static ssize_t super_block_attribute_show(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ struct super_block_attribute *sattr =
+ container_of(attr, struct super_block_attribute, attr);
+ struct super_block *sb = container_of(kobj, struct super_block, s_kobj);
+ if (!sattr->show)
+ return -EIO;
+
+ return sattr->show(sb, sattr, buf);
+}
+
+static ssize_t super_block_attribute_store(struct kobject *kobj,
+ struct attribute *attr, const char *buf, size_t count)
+{
+ struct super_block_attribute *sattr =
+ container_of(attr, struct super_block_attribute, attr);
+ struct super_block *sb = container_of(kobj, struct super_block, s_kobj);
+ if (!sattr->show)
+ return -EIO;
+
+ return sattr->store(sb, sattr, buf, count);
+}
+
+static void release_super(struct kobject *kobj)
{
- struct super_block *s = container_of(work, struct super_block,
- destroy_work);
+ struct super_block *s = container_of(kobj, struct super_block,
+ s_kobj);
int i;
for (i = 0; i < SB_FREEZE_LEVELS; i++)
@@ -146,11 +172,22 @@ static void destroy_super_work(struct work_struct *work)
kfree(s);
}
-static void destroy_super_rcu(struct rcu_head *head)
+static const struct sysfs_ops sb_sysfs_ops = {
+ .show = super_block_attribute_show,
+ .store = super_block_attribute_store,
+};
+
+static int register_kobj(struct super_block *sb)
{
- struct super_block *s = container_of(head, struct super_block, rcu);
- INIT_WORK(&s->destroy_work, destroy_super_work);
- schedule_work(&s->destroy_work);
+ struct kobj_type *ktype;
+ ktype = kzalloc(sizeof(struct kobj_type), GFP_USER);
+ if (IS_ERR(ktype))
+ return PTR_ERR(ktype);
+ ktype->sysfs_ops = &sb_sysfs_ops;
+ ktype->release = release_super;
+ sb->s_kobj.kset = sb->s_type->kset;
+ return kobject_init_and_add(&sb->s_kobj, ktype, NULL,
+ "%s", sb->s_id);
}
/**
@@ -167,7 +204,8 @@ static void destroy_super(struct super_block *s)
WARN_ON(!list_empty(&s->s_mounts));
kfree(s->s_subtype);
kfree(s->s_options);
- call_rcu(&s->rcu, destroy_super_rcu);
+ if (s->s_type->fs_flags & FS_CREATE_SYSFS)
+ kobject_del(&s->s_kobj);
}
/**
@@ -1021,7 +1059,8 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
deactivate_locked_super(s);
goto error;
}
-
+ if (s->s_type->fs_flags & FS_CREATE_SYSFS)
+ register_kobj(s);
s->s_flags |= MS_ACTIVE;
bdev->bd_super = s;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index cfea7b4..e6b9d89 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1317,6 +1317,29 @@ struct sb_writers {
struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
};
+struct super_block_attribute {
+ struct attribute attr;
+ ssize_t (*show)(struct super_block *sb, struct super_block_attribute *,
+ char *buf);
+ ssize_t (*store)(struct super_block *sb, struct super_block_attribute *,
+ const char *buf, size_t count);
+};
+
+#define SB_ATTR(_name, _mode) \
+struct super_block_attribute sb_attr_##_name = {\
+ .attr = {.name = __stringify(_name), \
+ .mode = _mode}, \
+ .show = _name##_show, \
+ .store = _name##_store, \
+}
+
+#define SB_ATTR_RO(_name) \
+struct super_block_attribute sb_attr_##_name = {\
+ .attr = {.name = __stringify(_name), \
+ .mode = S_IRUGO}, \
+ .show = _name##_show, \
+}
+
struct super_block {
struct list_head s_list; /* Keep this first */
dev_t s_dev; /* search index; _not_ kdev_t */
@@ -1406,8 +1429,6 @@ struct super_block {
*/
struct list_lru s_dentry_lru ____cacheline_aligned_in_smp;
struct list_lru s_inode_lru ____cacheline_aligned_in_smp;
- struct rcu_head rcu;
- struct work_struct destroy_work;
struct mutex s_sync_lock; /* sync serialisation lock */
@@ -1419,6 +1440,7 @@ struct super_block {
/* s_inode_list_lock protects s_inodes */
spinlock_t s_inode_list_lock ____cacheline_aligned_in_smp;
struct list_head s_inodes; /* all inodes */
+ struct kobject s_kobj;
};
extern struct timespec current_fs_time(struct super_block *sb);
--
2.6.6
--
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