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NFS: Fixup some outdated comments... 

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2006-12-13 15:23:48 -05:00
parent d30c8348a4
commit 7c85d9007d
1 changed files with 1 additions and 41 deletions
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42
fs/nfs/write.c
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@ -1,47 +1,7 @@
/*
* linux/fs/nfs/write.c
*
* Writing file data over NFS.
*
* We do it like this: When a (user) process wishes to write data to an
* NFS file, a write request is allocated that contains the RPC task data
* plus some info on the page to be written, and added to the inode's
* write chain. If the process writes past the end of the page, an async
* RPC call to write the page is scheduled immediately; otherwise, the call
* is delayed for a few seconds.
*
* Just like readahead, no async I/O is performed if wsize < PAGE_SIZE.
*
* Write requests are kept on the inode's writeback list. Each entry in
* that list references the page (portion) to be written. When the
* cache timeout has expired, the RPC task is woken up, and tries to
* lock the page. As soon as it manages to do so, the request is moved
* from the writeback list to the writelock list.
*
* Note: we must make sure never to confuse the inode passed in the
* write_page request with the one in page->inode. As far as I understand
* it, these are different when doing a swap-out.
*
* To understand everything that goes on here and in the NFS read code,
* one should be aware that a page is locked in exactly one of the following
* cases:
*
* - A write request is in progress.
* - A user process is in generic_file_write/nfs_update_page
* - A user process is in generic_file_read
*
* Also note that because of the way pages are invalidated in
* nfs_revalidate_inode, the following assertions hold:
*
* - If a page is dirty, there will be no read requests (a page will
* not be re-read unless invalidated by nfs_revalidate_inode).
* - If the page is not uptodate, there will be no pending write
* requests, and no process will be in nfs_update_page.
*
* FIXME: Interaction with the vmscan routines is not optimal yet.
* Either vmscan must be made nfs-savvy, or we need a different page
* reclaim concept that supports something like FS-independent
* buffer_heads with a b_ops-> field.
* Write file data over NFS.
*
* Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
*/