POSIX ACLs and richacls are both objects allocated by kmalloc() with a
reference count which are freed by kfree_rcu().  An inode can either
cache an access and a default POSIX ACL, or a richacl (richacls do not
have default acls).  To allow an inode to cache either of the two kinds
of acls, introduce a new base_acl type and convert i_acl and
i_default_acl to that type. In most cases, the vfs then doesn't have to
care which kind of acl an inode caches (if any).

Signed-off-by: Andreas Gruenbacher <agrue...@redhat.com>
---
 drivers/staging/lustre/lustre/llite/llite_lib.c |  2 +-
 fs/f2fs/acl.c                                   |  4 ++--
 fs/inode.c                                      |  4 ++--
 fs/jffs2/acl.c                                  |  6 ++++--
 fs/posix_acl.c                                  | 18 +++++++++---------
 include/linux/fs.h                              | 25 ++++++++++++++++++++++---
 include/linux/posix_acl.h                       | 12 ++++--------
 include/linux/richacl.h                         |  2 +-
 8 files changed, 45 insertions(+), 28 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/llite_lib.c 
b/drivers/staging/lustre/lustre/llite/llite_lib.c
index b4ed6c8..5766f69 100644
--- a/drivers/staging/lustre/lustre/llite/llite_lib.c
+++ b/drivers/staging/lustre/lustre/llite/llite_lib.c
@@ -1118,7 +1118,7 @@ void ll_clear_inode(struct inode *inode)
        }
 #ifdef CONFIG_FS_POSIX_ACL
        else if (lli->lli_posix_acl) {
-               LASSERT(atomic_read(&lli->lli_posix_acl->a_refcount) == 1);
+               LASSERT(atomic_read(&lli->lli_posix_acl->a_base.ba_refcount) == 
1);
                LASSERT(lli->lli_remote_perms == NULL);
                posix_acl_release(lli->lli_posix_acl);
                lli->lli_posix_acl = NULL;
diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c
index c8f25f7..a4207de 100644
--- a/fs/f2fs/acl.c
+++ b/fs/f2fs/acl.c
@@ -270,7 +270,7 @@ static struct posix_acl *f2fs_acl_clone(const struct 
posix_acl *acl,
                                sizeof(struct posix_acl_entry);
                clone = kmemdup(acl, size, flags);
                if (clone)
-                       atomic_set(&clone->a_refcount, 1);
+                       atomic_set(&clone->a_base.ba_refcount, 1);
        }
        return clone;
 }
@@ -282,7 +282,7 @@ static int f2fs_acl_create_masq(struct posix_acl *acl, 
umode_t *mode_p)
        umode_t mode = *mode_p;
        int not_equiv = 0;
 
-       /* assert(atomic_read(acl->a_refcount) == 1); */
+       /* assert(atomic_read(acl->a_base.ba_refcount) == 1); */
 
        FOREACH_ACL_ENTRY(pa, acl, pe) {
                switch(pa->e_tag) {
diff --git a/fs/inode.c b/fs/inode.c
index 78a17b8..2a387f4 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -233,9 +233,9 @@ void __destroy_inode(struct inode *inode)
 
 #ifdef CONFIG_FS_POSIX_ACL
        if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
-               posix_acl_release(inode->i_acl);
+               put_base_acl(inode->i_acl);
        if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
-               posix_acl_release(inode->i_default_acl);
+               put_base_acl(inode->i_default_acl);
 #endif
        this_cpu_dec(nr_inodes);
 }
diff --git a/fs/jffs2/acl.c b/fs/jffs2/acl.c
index 2f7a3c0..04a5836 100644
--- a/fs/jffs2/acl.c
+++ b/fs/jffs2/acl.c
@@ -294,13 +294,15 @@ int jffs2_init_acl_post(struct inode *inode)
        int rc;
 
        if (inode->i_default_acl) {
-               rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, 
inode->i_default_acl);
+               rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT,
+                                    *acl_by_type(inode, ACL_TYPE_DEFAULT));
                if (rc)
                        return rc;
        }
 
        if (inode->i_acl) {
-               rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, 
inode->i_acl);
+               rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS,
+                                    *acl_by_type(inode, ACL_TYPE_ACCESS));
                if (rc)
                        return rc;
        }
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 4fb17de..b3b2265 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -25,9 +25,9 @@ struct posix_acl **acl_by_type(struct inode *inode, int type)
 {
        switch (type) {
        case ACL_TYPE_ACCESS:
-               return &inode->i_acl;
+               return (struct posix_acl **)&inode->i_acl;
        case ACL_TYPE_DEFAULT:
-               return &inode->i_default_acl;
+               return (struct posix_acl **)&inode->i_default_acl;
        default:
                BUG();
        }
@@ -83,16 +83,16 @@ EXPORT_SYMBOL(forget_cached_acl);
 
 void forget_all_cached_acls(struct inode *inode)
 {
-       struct posix_acl *old_access, *old_default;
+       struct base_acl *old_access, *old_default;
        spin_lock(&inode->i_lock);
        old_access = inode->i_acl;
        old_default = inode->i_default_acl;
        inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
        spin_unlock(&inode->i_lock);
        if (old_access != ACL_NOT_CACHED)
-               posix_acl_release(old_access);
+               put_base_acl(old_access);
        if (old_default != ACL_NOT_CACHED)
-               posix_acl_release(old_default);
+               put_base_acl(old_default);
 }
 EXPORT_SYMBOL(forget_all_cached_acls);
 
@@ -129,7 +129,7 @@ EXPORT_SYMBOL(get_acl);
 void
 posix_acl_init(struct posix_acl *acl, int count)
 {
-       atomic_set(&acl->a_refcount, 1);
+       atomic_set(&acl->a_base.ba_refcount, 1);
        acl->a_count = count;
 }
 EXPORT_SYMBOL(posix_acl_init);
@@ -162,7 +162,7 @@ posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
                           sizeof(struct posix_acl_entry);
                clone = kmemdup(acl, size, flags);
                if (clone)
-                       atomic_set(&clone->a_refcount, 1);
+                       atomic_set(&clone->a_base.ba_refcount, 1);
        }
        return clone;
 }
@@ -384,7 +384,7 @@ static int posix_acl_create_masq(struct posix_acl *acl, 
umode_t *mode_p)
        umode_t mode = *mode_p;
        int not_equiv = 0;
 
-       /* assert(atomic_read(acl->a_refcount) == 1); */
+       /* assert(atomic_read(acl->a_base.ba_refcount) == 1); */
 
        FOREACH_ACL_ENTRY(pa, acl, pe) {
                 switch(pa->e_tag) {
@@ -439,7 +439,7 @@ static int __posix_acl_chmod_masq(struct posix_acl *acl, 
umode_t mode)
        struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
        struct posix_acl_entry *pa, *pe;
 
-       /* assert(atomic_read(acl->a_refcount) == 1); */
+       /* assert(atomic_read(acl->a_base.ba_refcount) == 1); */
 
        FOREACH_ACL_ENTRY(pa, acl, pe) {
                switch(pa->e_tag) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ba91a89..3c22c92 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -576,6 +576,12 @@ static inline void mapping_allow_writable(struct 
address_space *mapping)
 #define i_size_ordered_init(inode) do { } while (0)
 #endif
 
+struct base_acl {
+       union {
+               atomic_t ba_refcount;
+               struct rcu_head ba_rcu;
+       };
+};
 struct posix_acl;
 #define ACL_NOT_CACHED ((void *)(-1))
 
@@ -595,9 +601,9 @@ struct inode {
        kgid_t                  i_gid;
        unsigned int            i_flags;
 
-#ifdef CONFIG_FS_POSIX_ACL
-       struct posix_acl        *i_acl;
-       struct posix_acl        *i_default_acl;
+#if defined(CONFIG_FS_POSIX_ACL)
+       struct base_acl         *i_acl;
+       struct base_acl         *i_default_acl;
 #endif
 
        const struct inode_operations   *i_op;
@@ -3059,4 +3065,17 @@ static inline bool dir_relax(struct inode *inode)
 
 extern bool path_noexec(const struct path *path);
 
+static inline struct base_acl *get_base_acl(struct base_acl *acl)
+{
+       if (acl)
+               atomic_inc(&acl->ba_refcount);
+       return acl;
+}
+
+static inline void put_base_acl(struct base_acl *acl)
+{
+       if (acl && atomic_dec_and_test(&acl->ba_refcount))
+               kfree_rcu(acl, ba_rcu);
+}
+
 #endif /* _LINUX_FS_H */
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 3e96a6a..2c46441 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -43,10 +43,7 @@ struct posix_acl_entry {
 };
 
 struct posix_acl {
-       union {
-               atomic_t                a_refcount;
-               struct rcu_head         a_rcu;
-       };
+       struct base_acl         a_base;
        unsigned int            a_count;
        struct posix_acl_entry  a_entries[0];
 };
@@ -61,8 +58,7 @@ struct posix_acl {
 static inline struct posix_acl *
 posix_acl_dup(struct posix_acl *acl)
 {
-       if (acl)
-               atomic_inc(&acl->a_refcount);
+       get_base_acl(&acl->a_base);
        return acl;
 }
 
@@ -72,8 +68,8 @@ posix_acl_dup(struct posix_acl *acl)
 static inline void
 posix_acl_release(struct posix_acl *acl)
 {
-       if (acl && atomic_dec_and_test(&acl->a_refcount))
-               kfree_rcu(acl, a_rcu);
+       BUILD_BUG_ON(offsetof(struct posix_acl, a_base) != 0);
+       put_base_acl(&acl->a_base);
 }
 
 
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
index d5fa7b9..575ec32 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -94,7 +94,7 @@ static inline struct richacl *
 richacl_get(struct richacl *acl)
 {
        if (acl)
-               atomic_inc(&acl->a_refcount);
+               atomic_inc(&acl->a_base.ba_refcount);
        return acl;
 }
 
-- 
2.5.0

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