Subject: Re: letting userland issue FUA writes
To: Bill Studenmund <>
From: Christos Zoulas <>
List: tech-kern
Date: 03/15/2006 19:53:24
On Mar 15,  4:44pm, (Bill Studenmund) wrote:
-- Subject: Re: letting userland issue FUA writes

| Per call? Also, having to set/clear the FUA mode before a call will=20
| complicate concurrency; I must have a userlevel lock so that no operation=
| =20
| gets between an fcntl() and its write().

Yes, that was my concern when I proposed this. The inefficiency of the
extra system call plus the race condition.

| If separate file descriptors are the only option, so be it. But I was=20
| hoping for some other call API to help out.

I don't know. It seems to me something similar to writev might work, where
there is a flags field in iov. The problem I see is that there is no such
interface/api in POSIX and other people haven't had the need for this before.

I think that the right place for this might be to implement aio, and stuff
this capability somewhere in the aio request.