NFS: Fixup some outdated comments...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