Support for applications which need NFS or CIFS "share_deny" flags on open

From: Steve French
Date: Tue Dec 02 2008 - 11:31:39 EST

Some of the Wine community posted last month to the cifs mailing list
asking about a change needed for Wine for working properly over
network mounts, but the change is not really cifs specific and would
help other file systems as well so I wanted to mention it here. The
original post was:

Support for the flags they suggest would be easy for cifs (the
protocol has a field for this, and cifs clients on various other OS
set it), and should be fairly easy for NFSv4 (the RFC for NFSv4
specifies the "share_deny" field within the NFS open request, and
various clients, but not Linux, set it), and would allow WINE to
function properly over a network mount.

>we proffer to add into the file /usr/include/asm-generic/fcntl.h
> following flags:
>#define O_DENYREAD 004000000 /* Do not permit read access */
>#define O_DENYWRITE 010000000 /* Do not permit write access */
>#define O_DENYDELETE 020000000 /* Do not permit delete or rename
> operations*/

Presumably for applications on local mounts, wine mediates their own
mandatory locks, but this is impossible on network mounts without this
change (and can lead to data corruption).


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