On Tue, Dec 02, 2008 at 12:38:20PM -0700, Andreas Dilger wrote: > On Dec 02, 2008 10:31 -0600, Steve French wrote: > > 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: > > http://marc.info/?l=linux-cifs-client&m=122505569315992&w=2 > > > > 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). > > This is a disaster waiting to happen, and I would be against adding > such functionality to Linux. It would allow userspace applications > to implement a denial of service to any file that they can open (e.g. > open("/lib/libc-2.7.so", O_DENYREAD) would be really bad :-). Indeed. If these flags are added it should only be for network filesystem access, it would be a real mess for local access. I guess it makes sense for them to be the inverse of the Windows CreateFile call FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE as by default Linux clients would use all these bits for a normal open. Jeremy. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
