Re: [PATCH -V1 19/22] vfs: Cache richacl in struct inode

Aneesh Kumar K.V
2014-05-01T15:45:22Z

Dave Chinner <david@fromorbit.com> writes:

> On Sun, Apr 27, 2014 at 09:44:50PM +0530, Aneesh Kumar K.V wrote:
>> From: Andreas Gruenbacher <agruen@kernel.org>
>>
>> Cache richacls in struct inode so that this doesn't have to be done
>> individually in each filesystem.
>>
>> Signed-off-by: Andreas Gruenbacher <agruen@kernel.org>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> ---
>> fs/inode.c | 25 ++++++++++++++++++-----
>> include/linux/fs.h | 12 +++++++++--
>> include/linux/richacl.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 83 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/inode.c b/fs/inode.c
>> index f96d2a6f88cc..b96a16d5c653 100644
>> --- a/fs/inode.c
>> +++ b/fs/inode.c
>> @@ -18,6 +18,7 @@
>> #include <linux/buffer_head.h> /* for inode_has_buffers */
>> #include <linux/ratelimit.h>
>> #include <linux/list_lru.h>
>> +#include <linux/richacl.h>
>> #include "internal.h"
>>
>> /*
>> @@ -185,7 +186,12 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
>> 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 (IS_POSIXACL(inode))
>> + inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
>> +#endif
>> +#ifdef CONFIG_FS_RICHACL
>> + if (IS_RICHACL(inode))
>> + inode->i_richacl = ACL_NOT_CACHED;
>> #endif
>
> That's just plain wrong. i think this is what Christoph didn't like.
> An inode can have either a POSIX ACL or a RICH ACL, so there is no
> need for multiple pointers in the inode for them.

We don't really have multiple pointers

union {
#ifdef CONFIG_FS_POSIX_ACL
struct {
struct posix_acl *i_acl;
struct posix_acl *i_default_acl;
};
#endif
#ifdef CONFIG_FS_RICHACL
struct richacl *i_richacl;
#endif
};

But I understand what you are suggesting here. Will try to rework and
see how much easy/simpler it makes the code.

>
>>
>> #ifdef CONFIG_FSNOTIFY
>> @@ -240,10 +246,19 @@ 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);
>> - if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
>> - posix_acl_release(inode->i_default_acl);
>> + if (IS_POSIXACL(inode)) {
>> + if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
>> + posix_acl_release(inode->i_acl);
>> + if (inode->i_default_acl &&
>> + inode->i_default_acl != ACL_NOT_CACHED)
>> + posix_acl_release(inode->i_default_acl);
>> + }
>> +#endif
>> +#ifdef CONFIG_FS_RICHACL
>> + if (IS_RICHACL(inode)) {
>> + if (inode->i_richacl && inode->i_richacl != ACL_NOT_CACHED)
>> + richacl_put(inode->i_richacl);
>> + }
>> #endif
>
> if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
> acl_release(inode->i_acl);
>
> And all the mess of working out what acl needs releasing get taken
> out of of this code.

Understood. Will try to see how much I can simplify.

>
>> index 22d85798b520..95df64d21e55 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -492,6 +492,7 @@ static inline int mapping_writably_mapped(struct address_space *mapping)
>> #endif
>>
>> struct posix_acl;
>> +struct richacl;
>> #define ACL_NOT_CACHED ((void *)(-1))
>>
>> #define IOP_FASTPERM 0x0001
>> @@ -510,10 +511,17 @@ struct inode {
>> kgid_t i_gid;
>> unsigned int i_flags;
>>
>> + union {
>> #ifdef CONFIG_FS_POSIX_ACL
>> - struct posix_acl *i_acl;
>> - struct posix_acl *i_default_acl;
>> + struct {
>> + struct posix_acl *i_acl;
>> + struct posix_acl *i_default_acl;
>> + };
>> #endif
>> +#ifdef CONFIG_FS_RICHACL
>> + struct richacl *i_richacl;
>> +#endif
>> + };
>
>>
>> const struct inode_operations *i_op;
>> struct super_block *i_sb;
>> diff --git a/include/linux/richacl.h b/include/linux/richacl.h
>> index 88f95d78b897..a7db341e4ee9 100644
>> --- a/include/linux/richacl.h
>> +++ b/include/linux/richacl.h
>> @@ -191,6 +191,59 @@ richacl_put(struct richacl *acl)
>> kfree(acl);
>> }
>>
>> +#ifdef CONFIG_FS_RICHACL
>> +static inline struct richacl *get_cached_richacl(struct inode *inode)
>> +{
>> + struct richacl **p, *acl;
>> +
>> + p = &inode->i_richacl;
>> + acl = ACCESS_ONCE(*p);
>> + if (acl) {
>> + spin_lock(&inode->i_lock);
>> + acl = *p;
>> + if (acl != ACL_NOT_CACHED)
>> + acl = richacl_get(acl);
>> + spin_unlock(&inode->i_lock);
>> + }
>> + return acl;
>> +}
>> +
>> +static inline void set_cached_richacl(struct inode *inode,
>> + struct richacl *acl)
>> +{
>> + struct richacl *old = NULL;
>> + spin_lock(&inode->i_lock);
>> + old = inode->i_richacl;
>> + inode->i_richacl = richacl_get(acl);
>> + spin_unlock(&inode->i_lock);
>> + if (old != ACL_NOT_CACHED)
>> + richacl_put(old);
>> +}
>> +
>> +static inline void forget_cached_richacl(struct inode *inode)
>> +{
>> + struct richacl *old = NULL;
>> + spin_lock(&inode->i_lock);
>> + old = inode->i_richacl;
>> + inode->i_richacl = ACL_NOT_CACHED;
>> + spin_unlock(&inode->i_lock);
>> + if (old != ACL_NOT_CACHED)
>> + richacl_put(old);
>> +}
>> +
>> +static inline int negative_cached_richacl(struct inode *inode)
>> +{
>> + struct richacl **p, *acl;
>> +
>> + p = &inode->i_richacl;
>> + acl = ACCESS_ONCE(*p);
>> + if (acl)
>> + return 0;
>> + return 1;
>> +}
>> +
>> +#endif
>
> This is all just copy-and-paste from the posix_acl code with the RCU
> path-walk awareness removed from it. There should only be a single
> RCU aware version of these functions that does not care what type of
> ACL is in use.
>

Ok.

-aneesh