[Ocfs2-devel] [PATCH] ocfs2: Cache some system inodes of other nodes.

[Tao Ma]

Sunil Mushran wrote:
> On 08/12/2010 02:43 AM, Joel Becker wrote:
>> On Thu, Aug 12, 2010 at 05:03:16PM +0800, Tao Ma wrote:
>>> In ocfs2, we now only cache the inodes for global system file
>>> and the system inodes for our own slot. But we have some cases
>>> that we may need to access system inodes of other nodes, such
>>> as orphan scan, inode steal etc.
>>
>>     I don't see why you don't extend the existing cache and make one
>> cache.  Make it live the lifetime of the filesystem.  No real reason to
>> a) have to caches or b) limit the system inodes we might cache.  If we
>> don't have the lock we're going to re-read them anyway.
>
> Yeah... I have to agree. Will make it more readable.
>
> enum {
>         BAD_BLOCK_SYSTEM_INODE = 0,
>         GLOBAL_INODE_ALLOC_SYSTEM_INODE,
>         SLOT_MAP_SYSTEM_INODE,
> #define OCFS2_FIRST_ONLINE_SYSTEM_INODE SLOT_MAP_SYSTEM_INODE
>         HEARTBEAT_SYSTEM_INODE,
>         GLOBAL_BITMAP_SYSTEM_INODE,
>         USER_QUOTA_SYSTEM_INODE,
>         GROUP_QUOTA_SYSTEM_INODE,
> #define OCFS2_LAST_GLOBAL_SYSTEM_INODE GROUP_QUOTA_SYSTEM_INODE
> #define OCFS2_FIRST_LOCAL_SYSTEM_INODE ORPHAN_DIR_SYSTEM_INODE
>         ORPHAN_DIR_SYSTEM_INODE,
>         EXTENT_ALLOC_SYSTEM_INODE,
>         INODE_ALLOC_SYSTEM_INODE,
>         JOURNAL_SYSTEM_INODE,
>         LOCAL_ALLOC_SYSTEM_INODE,
>         TRUNCATE_LOG_SYSTEM_INODE,
>         LOCAL_USER_QUOTA_SYSTEM_INODE,
>         LOCAL_GROUP_QUOTA_SYSTEM_INODE,
>         NUM_SYSTEM_INODES
> };
> #define NUM_LOCAL_SYSTEM_INODES (NUM_SYSTEM_INODES - 
> OCFS2_FIRST_LOCAL_SYSTEM_INODE)
>
> struct ocfs2_super {
> ...
>         struct inode 
> *global_system_inodes[OCFS2_LAST_GLOBAL_SYSTEM_INODE];
>         struct inode **local_system_inodes;
> ...
> };
>
> local_system_inodes = kzalloc(sizeof(struct inode *) * osb->num_slots *
>                             NUM_LOCAL_SYSTEM_INODES;
>
>         /* avoid the lookup if cached in local system file array */
>         if (is_in_system_inode_array(osb, type, slot))
>                 arr = &(osb->system_inodes[type]);
>
> change to:
>
>         if (is_global_system_inode(type)
>                 arr = &(osb->global_system_inodes[type]);
>         else {
>                 BUG_ON(slot == OCFS2_INVALID_SLOT);
>                 BUG_ON(type < OCFS2_FIRST_LOCAL_SYSTEM_INODE ||
>                         type > LOCAL_GROUP_QUOTA_SYSTEM_INODE);
>                 tmp = (slot * NUM_LOCAL_SYSTEM_INODES) +
>                       (type - OCFS2_FIRST_LOCAL_SYSTEM_INODE);
>                 arr = &(osb->local_system_inodes[tmp];
>         }
>
> How does this look?
oh, since both of you prefer a simple system_inode array, I will rework 
it. Thanks.

Regards,
Tao