RCUify freeing acls, let check_acl() go ahead in RCU mode if acl is cached
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index a9c2fb2..b768110 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -9,6 +9,7 @@
#define __LINUX_POSIX_ACL_H
#include <linux/slab.h>
+#include <linux/rcupdate.h>
#define ACL_UNDEFINED_ID (-1)
@@ -38,7 +39,10 @@
};
struct posix_acl {
- atomic_t a_refcount;
+ union {
+ atomic_t a_refcount;
+ struct rcu_head a_rcu;
+ };
unsigned int a_count;
struct posix_acl_entry a_entries[0];
};
@@ -65,7 +69,7 @@
posix_acl_release(struct posix_acl *acl)
{
if (acl && atomic_dec_and_test(&acl->a_refcount))
- kfree(acl);
+ kfree_rcu(acl, a_rcu);
}
@@ -110,13 +114,9 @@
return acl;
}
-static inline int negative_cached_acl(struct inode *inode, int type)
+static inline struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
{
- struct posix_acl **p = acl_by_type(inode, type);
- struct posix_acl *acl = ACCESS_ONCE(*p);
- if (acl)
- return 0;
- return 1;
+ return rcu_dereference(*acl_by_type(inode, type));
}
static inline void set_cached_acl(struct inode *inode,
@@ -127,7 +127,7 @@
struct posix_acl *old;
spin_lock(&inode->i_lock);
old = *p;
- *p = posix_dup_acl(acl);
+ rcu_assign_pointer(*p, posix_acl_dup(acl));
spin_unlock(&inode->i_lock);
if (old != ACL_NOT_CACHED)
posix_acl_release(old);