Date: Mon, 18 Apr 2011 21:47:50 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: svn-src-head@freebsd.org, Matthew D Fleming <mdf@freebsd.org>, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r220791 - in head: lib/libc/sys sys/compat/freebsd32 sys/kern sys/sys Message-ID: <20110418194750.GD3097@garage.freebsd.pl> In-Reply-To: <20110418192810.GX48734@deviant.kiev.zoral.com.ua> References: <201104181632.p3IGWM5v077720@svn.freebsd.org> <20110418192810.GX48734@deviant.kiev.zoral.com.ua>
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--OaZoDhBhXzo6bW1J Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 18, 2011 at 10:28:10PM +0300, Kostik Belousov wrote: > > + if (offset + len > vap->va_size) { > > + VATTR_NULL(vap); > > + vap->va_size =3D offset + len; > > + error =3D VOP_SETATTR(vp, vap, td->td_ucred); > > + if (error !=3D 0) > > + goto out; > > + } > I still do not see a reason to do VOP_SETATTR() there. VOP_WRITE() will > do auto-extend as needed. Also, see below. Yeah, also when we extend file size we could skip reading zeros. > > + if (offset < vap->va_size) { [...] > > + } else { > > + bzero(buf, cur); > > + } > Wouldn't VOP_SETATTR() at the start of the function mostly prevent > this bzero from executing ? Once we drop the vnode lock, the file size can change under us, no? > I estimated what it would take to do the optimized implementation for UFS, > and I think that the following change would allow to lessen the code > duplication much. >=20 > What if the vnode lock drop and looping be handled by the syscall, instead > of the vop implementation ? In other words, allow the VOP_ALLOCATE() > to allocate less then requested, and return the allocated amount to > the caller. The loop would be centralized then, freeing fs from doing > the dance. Also, if fs considers that suitable, it would do a whole > allocation in one run. I'd still go with SEEK_DATA/SEEK_HOLE loop as I suggested on arch@. If you would like to spend time on it, having SEEK_DATA/SEEK_HOLE support in UFS would be beneficial for other purposes too. --=20 Pawel Jakub Dawidek http://www.wheelsystems.com FreeBSD committer http://www.FreeBSD.org Am I Evil? Yes, I Am! http://yomoli.com --OaZoDhBhXzo6bW1J Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAk2slWUACgkQForvXbEpPzQOEgCg15ceghLKdon8khGcub0z2pwg 3n8AnipfpoOnf6hpQ3nut1gvoRT/W+F6 =69mP -----END PGP SIGNATURE----- --OaZoDhBhXzo6bW1J--
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