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Message-ID: <20080424151235.GJ15214@ZenIV.linux.org.uk>
Date: Thu, 24 Apr 2008 16:12:35 +0100
From: Al Viro <viro@...IV.linux.org.uk>
To: Miklos Szeredi <miklos@...redi.hu>
Cc: akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
dave@...ux.vnet.ibm.com, ezk@...sunysb.edu, mhalcrow@...ibm.com,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 00/13] vfs: add helpers to check r/o bind mounts
On Thu, Apr 24, 2008 at 04:53:27PM +0200, Miklos Szeredi wrote:
> > > > RTFS. permission() doesn't do "is that vfsmount read-only" checks, exactly
> > > > because it's 100% bogus - either you cover it with entire area where we
> > > > are guaranteed to stay r/w, or it's by definition racy.
> > >
> > > I know that.
> > >
> > > That does not mean, that fh_verify() needs to do vfsmount r/o checks.
> > > AFAICS it's perfectly OK to do that later, around the vfs_ call.
> >
> > ... and around everything else that happens to be done after fh_verify
> > for write access, surely?
>
> What in particular? You have managed to avoid answering this question
> for the last...I don't know how many emails.
Oh, for fuck sake... grep and ye shall see. Right next to setattr we
have nfsd4_set_nfs4_acl(), with pair of set_nfsv4_acl_one(). I'd rather
have those two covered by a single will/wont range, TYVM.
nfsd_create() will happily do vfs_mkdir() and nfsd_create_setattr(). Ditto.
And while we are at it, losing the check for r/o in fh_verify() will sure
as hell require at least handling it separately on the normal write path.
> > Note that e.g. nfsd_setattr() does _not_ call
> > vfs_<anything>()...
>
> Yes it does: notify_change(). It's vfs_setattr() under a pseudonym.
Are you going to move the will/wont in there? Because there's a bunch of
stuff in fs/open.c that will disagree...
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