Prasanna,
generic_file_read()
do_generic_file_read()
In do_generic_file_read(), you first try to find the data in page-cache, ==>
page_hash(mapping,index) and __find_page_nolock(mapping,index,hash)
functions.....
If we get the corresponding page from page-cache and page data is Uptodate, then we are good-to-go, else address_space's ops readpage() called on that page.
If we do not find the corres. page in page-cache, page_cache_alloc() and add_to_page_cache() path will be taken. Then, the readpage() is done for the alloc'ed page.
Hope this helps.
Thanks,
Vinod
On Wed, 22 Sep 2004 prasanna wakhare wrote :
>Hi,
>Regarding ramfs,it performs read and most other
>filesystems including nfs do with generic_file_read,
>which i think might calss the readpage operation
>internal to filesystem,the readpage arguments consists
>of
>(struct file *,struct page *) .....
>this means the page allocation is dine by VFS itself?
>If this is true most filesystems including NFS
>explicitly allocates Page,
>I'm really confused regarding relation of Page cache
>and file system,
>Please if someone clear my doubts....
>Thanks
>Prasanna
>
>
>
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