Re: Sick VFS question

[David Chow <davidchow@shaolinmicro.com>]

Ion Badulescu wrote:

>On Tue, 25 Feb 2003, Charles P. Wright wrote:
>
>  
>
>>AFAIK, In FiST-lite what happens is the upper level (wrapfs) inode has its
>>address space operations set to the operations of the lower level (e.g.,
>>EXT2) inode.  A quick look at the code seemed to confirm this.
>>    
>>
>
>Hmm. You're probably right (you've been hacking that code more recently
>than I have...). Anyway, what I said initially was definitely the original
>approach for FiST-lite, and I guess my memory is getting fuzzy on recent
>details, even though I actively worked on them. :-)
>  
>
 From what I know about FiST, this is not quite true. The aops of wrapfs 
inode are not pointed to the lower level fs's aops. Most of the address 
space operations have a struct page, which a struct page have its 
mapping and host ref to inode. The lower level inode is ref by the 
wrapfs inode private data. The wrapgs has its own page cache and looks 
like a separate fs to the VFS in all aspects.

David