I'm failing to think of what can trigger an open_downgrade?
I thought the following example should trigger an open downgrade:
fd0 = open(foo, RDRW) -- should be open on the wire for "both"
fd1 = open(foo, RDONLY) -- should be open on the wire for "read"
close(fd0) -- should trigger an open_downgrade
read(fd1)
close(fd1)
However this commit says that it's not allowed by the spec.
commit cd9288ffaea4359d5cfe2b8d264911506aed26a4
Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date: Thu Sep 18 11:51:32 2014 -0400
NFSv4: Fix another bug in the close/open_downgrade code
James Drew reports another bug whereby the NFS client is now sending
an OPEN_DOWNGRADE in a situation where it should really have sent a
CLOSE: the client is opening the file for O_RDWR, but then trying to
do a downgrade to O_RDONLY, which is not allowed by the NFSv4 spec.
Reported-by: James Drews <drews@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/541AD7E5.8020409@xxxxxxxxxxxxx
Fixes: aee7af356e15 (NFSv4: Fix problems with close in the presence...)
Cc: stable@xxxxxxxxxxxxxxx # 2.6.33+
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
If RDWR to RDONLY isn't allowed then why do we have OPEN_DOWNGRADE at all?
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