Re: [PATCH 5/5] Stop pinning dentries & inodes for leaves

[viro@parcelfarce.linux.theplanet.co.uk]

On Thu, Jul 29, 2004 at 03:44:49PM -0500, Maneesh Soni wrote:
> 
> 
> 
> o This patch stops the pinning of non-directory or leaf dentries and inodes. 
>   The leaf dentries and inodes are created during lookup based on the
>   entries on sysfs_dirent tree. These leaves are removed from the dcache
>   through the VFS dentry ageing process during shrink dcache operations. Thus
>   reducing about 80% of sysfs lowmem needs.
> 
> o This implments the ->lookup() for sysfs directory inodes and allocates
>   dentry and inode if the lookup is successful and avoids the need of 
>   allocating and pinning of dentry and inodes during the creation of 
>   corresponding sysfs leaf entry. As of now the implementation has not 
>   required negative dentry creation on failed lookup. As sysfs is still a
>   RAM based filesystem, negative dentries are not of any use IMO.
> 
> o The leaf dentry allocated after successful lookup is connected to the 
>   existing corresponding sysfs_dirent through the d_fsdata field. This 
>   increments the ref count of sysfs_dirent. The ref count is released through 
>   ->d_iput() dentry_operation when dentry dies.

ACK; there's some reordering that might make sense here, but that depends on
what will fall out of changes in previous chunks.