patch-2.1.32 linux/fs/nfs/README

• Lines: 115
• Date: Wed Dec 31 16:00:00 1969
• Orig file: v2.1.31/linux/fs/nfs/README
• Orig date: Thu Apr 25 05:04:50 1996

diff -u --recursive --new-file v2.1.31/linux/fs/nfs/README linux/fs/nfs/README
@@ -1,114 +0,0 @@
-
-
-    This is an NFS client for Linux that supports async RPC calls for
-    read-ahead (and hopefully soon, write-back) on regular files. 
-
-    The implementation uses a straightforward nfsiod scheme.  After
-    trying out a number of different concepts, I finally got back to
-    this concept, because everything else either didn't work or gave me
-    headaches. It's not flashy, but it works without hacking into any
-    other regions of the kernel.
-
-
-    HOW TO USE
-
-    This stuff compiles as a loadable module (I developed it on 1.3.77).
-    Simply type mkmodule, and insmod nfs.o. This will start four nfsiod's
-    at the same time (which will show up under the pseudonym of insmod in
-    ps-style listings).
-
-    Alternatively, you can put it right into the kernel: remove everything
-    from fs/nfs, move the Makefile and all *.c to this directory, and
-    copy all *.h files to include/linux.
-
-    After mounting, you should be able to watch (with tcpdump) several
-    RPC READ calls being placed simultaneously.
-
-
-    HOW IT WORKS
-
-    When a process reads from a file on an NFS volume, the following
-    happens:
-
-     *	nfs_file_read sets file->f_reada if more than 1K is
-    	read at once. It then calls generic_file_read.
-
-     *	generic_file_read requests one ore more pages via
-    	nfs_readpage.
-
-     *	nfs_readpage allocates a request slot with an nfsiod
-    	daemon, fills in the READ request, sends out the
-    	RPC call, kicks the daemon, and returns.
-    	If there's no free biod, nfs_readpage places the
-    	call directly, waiting for the reply (sync readpage).
-
-     *	nfsiod calls nfs_rpc_doio to collect the reply. If the
-    	call was successful, it sets page->uptodate and
-    	wakes up all processes waiting on page->wait;
-
-    This is the rough outline only. There are a few things to note:
-
-     *	Async RPC will not be tried when server->rsize < PAGE_SIZE.
-
-     *	When an error occurs, nfsiod has no way of returning
-    	the error code to the user process. Therefore, it flags
-    	page->error and wakes up all processes waiting on that
-    	page (they usually do so from within generic_readpage).
-
-    	generic_readpage finds that the page is still not
-    	uptodate, and calls nfs_readpage again. This time around,
-    	nfs_readpage notices that page->error is set and
-    	unconditionally does a synchronous RPC call.
-
-    	This area needs a lot of improvement, since read errors
-    	are not that uncommon (e.g. we have to retransmit calls
-    	if the fsuid is different from the ruid in order to
-    	cope with root squashing and stuff like this).
-
-	Retransmits with fsuid/ruid change should be handled by
-	nfsiod, but this doesn't come easily (a more general nfs_call
-	routine that does all this may be useful...)
-
-     *	To save some time on readaheads, we save one data copy
-    	by frobbing the page into the iovec passed to the
-	RPC code so that the networking layer copies the
-    	data into the page directly.
-
-    	This needs to be adjustable (different authentication
-    	flavors; AUTH_NULL versus AUTH_SHORT verifiers).
-
-     *	Currently, a fixed number of nfsiod's is spawned from
-    	within init_nfs_fs. This is problematic when running
-    	as a loadable module, because this will keep insmod's
-    	memory allocated. As a side-effect, you will see the
-    	nfsiod processes listed as several insmod's when doing
-    	a `ps.'
-
-     * 	This NFS client implements server congestion control via
-	Van Jacobson slow start as implemented in 44BSD. I haven't
-	checked how well this behaves, but since Rick Macklem did
-	it this way, it should be okay :-)
-
-
-    WISH LIST
-
-    After giving this thing some testing, I'd like to add some more
-    features:
-
-     *	Some sort of async write handling. True write-back doesn't
-	work with the current kernel (I think), because invalidate_pages
-	kills all pages, regardless of whether they're dirty or not.
-	Besides, this may require special bdflush treatment because
-	write caching on clients is really hairy.
-
-	Alternatively, a write-through scheme might be useful where
-	the client enqueues the request, but leaves collecting the
-	results to nfsiod. Again, we need a way to pass RPC errors
-	back to the application.
-
-     *	Support for different authentication flavors.
-
-     *	/proc/net/nfsclnt (for nfsstat, etc.).
-
-March 29, 1996
-Olaf Kirch <okir@monad.swb.de>