Shared access flags

Shared access flags

[Pavel Shilovsky]

Hello!
We have situation during our work with Wine and Cifs-client  then we have 
to use sharing access policy to files and we used 3 free bits from 21 to 
23 of attribute flag(it allows to do NT-semantic for opening files in open() 
and it is neccesary for correct implementation of function NTCreateFile in 
Wine). We think that it'll be useful not only for us and 
we proffer to add into the file kernel/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*/

Yes, it'll change semantic of calling open() function, but by default(if 
not to use these flags) functionality won't changed, and if we use it 
we'll acquire new resources for organization file access policy. On 
the other hand, we patched cifs with inverting these flags, because 
according to CIFS protocol
#define FILE_SHARE_ALL    0x00000007
ones have opposite meaning.

Here is our patches http://git.etersoft.ru/people/kipruss/packages/?p=cifs-2.6.git;a=shortlog;h=refs/heads/etersoft-to-kernel

Yours faithfully,
Pavel Shilovsky.