To make list_lru per-memcg, I'll have to add some code that might sleep
to list_lru_destroy(), but it is impossible to do now, because
list_lru_destroy() is currently called by destroy_super(), which can be
called in atomic context from __put_super().
To overcome this, in this patch I make __put_super() schedule the super
block destruction in an asynchronous work instead of calling
destroy_super() directly.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Glauber Costa <glommer@xxxxxxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
fs/super.c | 10 +++++++++-
include/linux/fs.h | 2 ++
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/fs/super.c b/fs/super.c
index ff9ff5fad70c..33cbff3769e7 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -147,6 +147,13 @@ static void destroy_super(struct super_block *s)
kfree_rcu(s, rcu);
}
+static void destroy_super_work_func(struct work_struct *w)
+{
+ struct super_block *s = container_of(w, struct super_block, destroy);
+
+ destroy_super(s);
+}
+
/**
* alloc_super - create new superblock
* @type: filesystem type superblock should belong to
@@ -182,6 +189,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
INIT_HLIST_NODE(&s->s_instances);
INIT_HLIST_BL_HEAD(&s->s_anon);
INIT_LIST_HEAD(&s->s_inodes);
+ INIT_WORK(&s->destroy, destroy_super_work_func);
if (list_lru_init(&s->s_dentry_lru))
goto fail;
@@ -239,7 +247,7 @@ static void __put_super(struct super_block *sb)
{
if (!--sb->s_count) {
list_del_init(&sb->s_list);
- destroy_super(sb);
+ schedule_work(&sb->destroy);
}
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3a87b0254408..200cbf804335 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1328,7 +1328,9 @@ 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;
};
extern struct timespec current_fs_time(struct super_block *sb);
--
1.7.10.4
--
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