Re: [PATCH v13 12/51] vfs: Cache richacl in struct inode

Andreas Dilger
2015-11-04T02:03:41Z

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On Nov 3, 2015, at 8:16 AM, Andreas Gruenbacher <agruenba@redhat.com> wrote:
>
> Cache richacls in struct inode so that this doesn't have to be done
> individually in each filesystem. This is similar to POSIX ACLs.
>
> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
> ---
> fs/inode.c | 11 ++++++--
> fs/posix_acl.c | 2 +-
> fs/richacl_base.c | 4 +--
> fs/richacl_inode.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/fs.h | 5 +++-
> include/linux/richacl.h | 15 ++++++----
> 6 files changed, 100 insertions(+), 12 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index 2a387f4..8462ddb 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -174,8 +174,11 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
> inode->i_private = NULL;
> inode->i_mapping = mapping;
> INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
> -#ifdef CONFIG_FS_POSIX_ACL
> - inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
> +#if defined(CONFIG_FS_POSIX_ACL) || defined(CONFIG_FS_RICHACL)
> + inode->i_acl = ACL_NOT_CACHED;
> +# if defined(CONFIG_FS_POSIX_ACL)
> + inode->i_default_acl = ACL_NOT_CACHED;
> +# endif
> #endif
>
> #ifdef CONFIG_FSNOTIFY
> @@ -231,11 +234,13 @@ void __destroy_inode(struct inode *inode)
> atomic_long_dec(&inode->i_sb->s_remove_count);
> }
>
> -#ifdef CONFIG_FS_POSIX_ACL
> +#if defined(CONFIG_FS_POSIX_ACL) || defined(CONFIG_FS_RICHACL)
> if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
> put_base_acl(inode->i_acl);
> +# if defined(CONFIG_FS_POSIX_ACL)
> if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
> put_base_acl(inode->i_default_acl);
> +# endif
> #endif
> this_cpu_dec(nr_inodes);
> }
> diff --git a/fs/posix_acl.c b/fs/posix_acl.c
> index b3b2265..1d766a5 100644
> --- a/fs/posix_acl.c
> +++ b/fs/posix_acl.c
> @@ -38,7 +38,7 @@ 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);
> - if (acl) {
> + if (acl && IS_POSIXACL(inode)) {
> spin_lock(&inode->i_lock);
> acl = *p;
> if (acl != ACL_NOT_CACHED)
> diff --git a/fs/richacl_base.c b/fs/richacl_base.c
> index 69b806c..d0ab5e9 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);
> + atomic_set(&acl->a_base.ba_refcount, 1);
> 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);
> + atomic_set(&dup->a_base.ba_refcount, 1);

These two calls should be base_acl_init(). There isn't any point to have
an abstraction that is only used by the posix_acl* code and not the richacl
code, as it will just result in richacl breaking in the future if/when the
abstraction is changed.

> }
> return dup;
> }
> diff --git a/fs/richacl_inode.c b/fs/richacl_inode.c
> index 99b3c93..c41a6c4 100644
> --- a/fs/richacl_inode.c
> +++ b/fs/richacl_inode.c
> @@ -20,6 +20,81 @@
> #include <linux/slab.h>
> #include <linux/richacl.h>
>
> +struct richacl *get_cached_richacl(struct inode *inode)
> +{
> + struct richacl *acl;
> +
> + acl = (struct richacl *)ACCESS_ONCE(inode->i_acl);
> + if (acl && IS_RICHACL(inode)) {
> + spin_lock(&inode->i_lock);
> + acl = (struct richacl *)inode->i_acl;
> + if (acl != ACL_NOT_CACHED)
> + acl = richacl_get(acl);
> + spin_unlock(&inode->i_lock);
> + }
> + return acl;
> +}
> +EXPORT_SYMBOL_GPL(get_cached_richacl);
> +
> +struct richacl *get_cached_richacl_rcu(struct inode *inode)
> +{
> + return (struct richacl *)rcu_dereference(inode->i_acl);
> +}
> +EXPORT_SYMBOL_GPL(get_cached_richacl_rcu);
> +
> +void set_cached_richacl(struct inode *inode, struct richacl *acl)
> +{
> + struct base_acl *old = NULL;
> +
> + spin_lock(&inode->i_lock);
> + old = inode->i_acl;
> + rcu_assign_pointer(inode->i_acl, &richacl_get(acl)->a_base);
> + spin_unlock(&inode->i_lock);
> + if (old != ACL_NOT_CACHED)
> + put_base_acl(old);
> +}
> +EXPORT_SYMBOL_GPL(set_cached_richacl);
> +
> +void forget_cached_richacl(struct inode *inode)
> +{
> + struct base_acl *old = NULL;
> +
> + spin_lock(&inode->i_lock);
> + old = inode->i_acl;
> + inode->i_acl = ACL_NOT_CACHED;
> + spin_unlock(&inode->i_lock);
> + if (old != ACL_NOT_CACHED)
> + put_base_acl(old);
> +}
> +EXPORT_SYMBOL_GPL(forget_cached_richacl);
> +
> +struct richacl *get_richacl(struct inode *inode)
> +{
> + struct richacl *acl;
> +
> + acl = get_cached_richacl(inode);
> + if (acl != ACL_NOT_CACHED)
> + return acl;
> +
> + if (!IS_RICHACL(inode))
> + return NULL;
> +
> + /*
> + * A filesystem can force a ACL callback by just never filling the
> + * ACL cache. But normally you'd fill the cache either at inode
> + * instantiation time, or on the first ->get_richacl call.
> + *
> + * If the filesystem doesn't have a get_richacl() function at all,
> + * we'll just create the negative cache entry.
> + */
> + if (!inode->i_op->get_richacl) {
> + set_cached_richacl(inode, NULL);
> + return NULL;
> + }
> + return inode->i_op->get_richacl(inode);
> +}
> +EXPORT_SYMBOL_GPL(get_richacl);
> +
> /**
> * richacl_permission - richacl permission check algorithm
> * @inode: inode to check
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 08fde42..d91deef 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -583,6 +583,7 @@ struct base_acl {
> };
> };
> struct posix_acl;
> +struct richacl;
> #define ACL_NOT_CACHED ((void *)(-1))
>
> #define IOP_FASTPERM 0x0001
> @@ -601,9 +602,11 @@ struct inode {
> kgid_t i_gid;
> unsigned int i_flags;
>
> -#if defined(CONFIG_FS_POSIX_ACL)
> +#if defined(CONFIG_FS_POSIX_ACL) || defined(CONFIG_FS_RICHACL)
> struct base_acl *i_acl;
> +# if defined(CONFIG_FS_POSIX_ACL)
> struct base_acl *i_default_acl;
> +# endif
> #endif
>
> const struct inode_operations *i_op;
> diff --git a/include/linux/richacl.h b/include/linux/richacl.h
> index 2baef35..de7d0d9 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;
> unsigned int a_owner_mask;
> unsigned int a_group_mask;
> unsigned int a_other_mask;

This should be in the previous patch where this wrapper is introduced.

> @@ -56,8 +56,7 @@ struct richacl {
> static inline struct richacl *
> richacl_get(struct richacl *acl)
> {
> - if (acl)
> - atomic_inc(&acl->a_base.ba_refcount);
> + get_base_acl(&acl->a_base);

Same.

> return acl;
> }
>
> @@ -67,10 +66,16 @@ 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);
> + put_base_acl(&acl->a_base);

Same.

> }
>
> +extern struct richacl *get_cached_richacl(struct inode *);
> +extern struct richacl *get_cached_richacl_rcu(struct inode *);
> +extern void set_cached_richacl(struct inode *, struct richacl *);
> +extern void forget_cached_richacl(struct inode *);
> +extern struct richacl *get_richacl(struct inode *);
> +
> /**
> * richace_is_owner - check if @ace is an OWNER@ entry
> */
> --
> 2.5.0
>

Cheers, Andreas

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