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RCUify freeing acls, let check_acl() go ahead in RCU mode if acl is cached

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2011-08-02 21:32:13 -04:00
parent 951c0d660a
commit 3567866bf2
2 changed files with 15 additions and 20 deletions
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18
include/linux/posix_acl.h
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@@ -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_entry {
};
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 @@ static inline void
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 @@ static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
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 @@ static inline void set_cached_acl(struct inode *inode,
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);