Re: patch: NFS and O_EXCL. Also: is O_EXCL really atomic?
Alan Cox (firstname.lastname@example.org)
Sat, 14 Sep 1996 21:56:53 +0100 (BST)
> This also brings up another question. In the Linux FS code, O_EXCL
> is treated by the VFS layer by first testing if the file is present,
> and then creating the file if not. It looks to me as if it could be
> possible that another process could be scheduled between the test and
> the create. This chance is really small, but still.. I don't know
> enough of the VFS layer to see if this is really true, though.
If that can happen its actually very serious because that has security
implications in some applications, and we would have to fix it ASAP.
Can an FS hacker verify that.
The O_EXCL for NFS looks a good fix. Bit hackish but good for 2.0