[PATCH v17 11/22] vfs: Cache base_acl objects in inodes

From: Andreas Gruenbacher
Date: Mon Jan 11 2016 - 10:23:25 EST

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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 care which
kind of acl an inode caches (if any).

Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
---
drivers/staging/lustre/lustre/llite/llite_lib.c | 2 +-
fs/f2fs/acl.c | 4 +--
fs/inode.c | 4 +--
fs/jffs2/acl.c | 10 ++++--
fs/posix_acl.c | 41 +++++++++++++------------
fs/richacl_base.c | 4 +--
include/linux/fs.h | 34 ++++++++++++++++++--
include/linux/posix_acl.h | 12 +++-----
include/linux/richacl.h | 9 +++---
9 files changed, 75 insertions(+), 45 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/llite_lib.c b/drivers/staging/lustre/lustre/llite/llite_lib.c
index 4a8c759..cfafdcc 100644
--- a/drivers/staging/lustre/lustre/llite/llite_lib.c
+++ b/drivers/staging/lustre/lustre/llite/llite_lib.c
@@ -1073,7 +1073,7 @@ 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(base_acl_refcount(&lli->lli_posix_acl->a_base) == 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..9646197 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);
+ base_acl_init(&clone->a_base);
}
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(base_acl_refcount(&acl->a_base) == 1); */

FOREACH_ACL_ENTRY(pa, acl, pe) {
switch(pa->e_tag) {
diff --git a/fs/inode.c b/fs/inode.c
index 1be5f90..1d6d035 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);
+ base_acl_put(inode->i_acl);
if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
- posix_acl_release(inode->i_default_acl);
+ base_acl_put(inode->i_default_acl);
#endif
this_cpu_dec(nr_inodes);
}
diff --git a/fs/jffs2/acl.c b/fs/jffs2/acl.c
index 2f7a3c0..569cb1b 100644
--- a/fs/jffs2/acl.c
+++ b/fs/jffs2/acl.c
@@ -294,13 +294,19 @@ 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);
+ struct posix_acl *default_acl = container_of(
+ inode->i_default_acl, struct posix_acl, a_base);
+
+ rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, default_acl);
if (rc)
return rc;
}

if (inode->i_acl) {
- rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
+ struct posix_acl *acl = container_of(
+ inode->i_acl, struct posix_acl, a_base);
+
+ rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, acl);
if (rc)
return rc;
}
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 55f2445..743b6dc 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -21,7 +21,7 @@
#include <linux/export.h>
#include <linux/user_namespace.h>

-static struct posix_acl **acl_by_type(struct inode *inode, int type)
+static struct base_acl **acl_by_type(struct inode *inode, int type)
{
switch (type) {
case ACL_TYPE_ACCESS:
@@ -35,63 +35,64 @@ static struct posix_acl **acl_by_type(struct inode *inode, int type)

struct posix_acl *get_cached_acl(struct inode *inode, int type)
{
- struct posix_acl **p = acl_by_type(inode, type);
- struct posix_acl *acl = ACCESS_ONCE(*p);
+ struct base_acl **p = acl_by_type(inode, type);
+ struct base_acl *acl = ACCESS_ONCE(*p);
if (acl) {
spin_lock(&inode->i_lock);
acl = *p;
if (acl != ACL_NOT_CACHED)
- acl = posix_acl_dup(acl);
+ base_acl_get(acl);
spin_unlock(&inode->i_lock);
}
- return acl;
+ return container_of(acl, struct posix_acl, a_base);
}
EXPORT_SYMBOL(get_cached_acl);

struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
{
- return rcu_dereference(*acl_by_type(inode, type));
+ struct base_acl *acl = rcu_dereference(*acl_by_type(inode, type));
+ return container_of(acl, struct posix_acl, a_base);
}
EXPORT_SYMBOL(get_cached_acl_rcu);

void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
{
- struct posix_acl **p = acl_by_type(inode, type);
- struct posix_acl *old;
+ struct base_acl **p = acl_by_type(inode, type);
+ struct base_acl *old;
spin_lock(&inode->i_lock);
old = *p;
- rcu_assign_pointer(*p, posix_acl_dup(acl));
+ rcu_assign_pointer(*p, &posix_acl_dup(acl)->a_base);
spin_unlock(&inode->i_lock);
if (old != ACL_NOT_CACHED)
- posix_acl_release(old);
+ base_acl_put(old);
}
EXPORT_SYMBOL(set_cached_acl);

void forget_cached_acl(struct inode *inode, int type)
{
- struct posix_acl **p = acl_by_type(inode, type);
- struct posix_acl *old;
+ struct base_acl **p = acl_by_type(inode, type);
+ struct base_acl *old;
spin_lock(&inode->i_lock);
old = *p;
*p = ACL_NOT_CACHED;
spin_unlock(&inode->i_lock);
if (old != ACL_NOT_CACHED)
- posix_acl_release(old);
+ base_acl_put(old);
}
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);
+ base_acl_put(old_access);
if (old_default != ACL_NOT_CACHED)
- posix_acl_release(old_default);
+ base_acl_put(old_default);
}
EXPORT_SYMBOL(forget_all_cached_acls);

@@ -128,7 +129,7 @@ EXPORT_SYMBOL(get_acl);
void
posix_acl_init(struct posix_acl *acl, int count)
{
- atomic_set(&acl->a_refcount, 1);
+ base_acl_init(&acl->a_base);
acl->a_count = count;
}
EXPORT_SYMBOL(posix_acl_init);
@@ -161,7 +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);
+ base_acl_init(&clone->a_base);
}
return clone;
}
@@ -383,7 +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(base_acl_refcount(&acl->a_base) == 1); */

FOREACH_ACL_ENTRY(pa, acl, pe) {
switch(pa->e_tag) {
@@ -438,7 +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(base_acl_refcount(&acl->a_base) == 1); */

FOREACH_ACL_ENTRY(pa, acl, pe) {
switch(pa->e_tag) {
diff --git a/fs/richacl_base.c b/fs/richacl_base.c
index 69b806c..5826842 100644
--- a/fs/richacl_base.c
+++ b/fs/richacl_base.c
@@ -33,7 +33,7 @@ richacl_alloc(int count, gfp_t gfp)
struct richacl *acl = kzalloc(size, gfp);

if (acl) {
- atomic_set(&acl->a_refcount, 1);
+ base_acl_init(&acl->a_base);
acl->a_count = count;
}
return acl;
@@ -52,7 +52,7 @@ richacl_clone(const struct richacl *acl, gfp_t gfp)

if (dup) {
memcpy(dup, acl, size);
- atomic_set(&dup->a_refcount, 1);
+ base_acl_init(&dup->a_base);
}
return dup;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e9e1139..c7f254b 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;
@@ -3045,4 +3051,26 @@ static inline bool dir_relax(struct inode *inode)

extern bool path_noexec(const struct path *path);

+static inline void base_acl_get(struct base_acl *acl)
+{
+ if (acl)
+ atomic_inc(&acl->ba_refcount);
+}
+
+static inline void base_acl_put(struct base_acl *acl)
+{
+ if (acl && atomic_dec_and_test(&acl->ba_refcount))
+ kfree_rcu(acl, ba_rcu);
+}
+
+static inline void base_acl_init(struct base_acl *acl)
+{
+ atomic_set(&acl->ba_refcount, 1);
+}
+
+static inline int base_acl_refcount(struct base_acl *acl)
+{
+ return atomic_read(&acl->ba_refcount);
+}
+
#endif /* _LINUX_FS_H */
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 5b5a80c..cef5428 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; /* must be first, see posix_acl_release() */
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);
+ base_acl_get(&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);
+ base_acl_put(&acl->a_base);
}

diff --git a/include/linux/richacl.h b/include/linux/richacl.h
index 1d9f5f7..7628fad 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -31,7 +31,7 @@ struct richace {
};

struct richacl {
- atomic_t a_refcount;
+ struct base_acl a_base; /* must be first, see richacl_put() */
unsigned int a_owner_mask;
unsigned int a_group_mask;
unsigned int a_other_mask;
@@ -56,8 +56,7 @@ struct richacl {
static inline struct richacl *
richacl_get(struct richacl *acl)
{
- if (acl)
- atomic_inc(&acl->a_refcount);
+ base_acl_get(&acl->a_base);
return acl;
}

@@ -67,8 +66,8 @@ richacl_get(struct richacl *acl)
static inline void
richacl_put(struct richacl *acl)
{
- if (acl && atomic_dec_and_test(&acl->a_refcount))
- kfree(acl);
+ BUILD_BUG_ON(offsetof(struct richacl, a_base) != 0);
+ base_acl_put(&acl->a_base);
}

/**
--
2.5.0

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