Date: Mon, 8 Nov 2010 17:10:28 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-fs@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: The state of Giant lock in the file systems? Message-ID: <20101108151028.GI2392@deviant.kiev.zoral.com.ua> In-Reply-To: <201011081004.59640.jhb@freebsd.org> References: <ib8qda$nat$1@dough.gmane.org> <201011081004.59640.jhb@freebsd.org>
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--SvH2i/6Q4qfAo9X5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 08, 2010 at 10:04:59AM -0500, John Baldwin wrote: > On Monday, November 08, 2010 7:28:26 am Ivan Voras wrote: > > I was looking at fusefs sources and there is a dance it does with the > > Giant lock which looks fishy. > >=20 > > Grepping for "-ir giant" in /sys/fs on 8-stable shows only a handful of > > mentionings, but if I understand it correctly only these "active" insta= nces: > >=20 > > 1) one set of mtx_assert() calls on it in pseudofs, which I can't figure > > out what they're guarding > > 2) some manual locking and unlocking in nfsclient which appears to only > > guard printf() (???) > > 3) some more locking in nfsserver which apparently is only there to > > guard the underlying local file system > > 4) coda, which appears to be the only one marked with D_NEEDGIANT, but > > doesn't do much of its own interfacing with it > >=20 > > Except for these, is there any more magic that would need to be resolved > > to excise Giant from VFS? > >=20 > > Would it be correct to think that coda is the single biggest obstacle? >=20 > Err, all the VFS_LOCK_GIANT() stuff for filesystems that do not have=20 > MNTK_MPSAFE set. I believe the currently MPSAFE fs's are UFS, ZFS, MSDOS= FS, > CD9660, UDF, NFS client, and devfs. I think all others are !MPSAFE still. pseudofs-based fses are mpsafe too. I already claimed several times that I will remove VFS_LOCK_GIANT after smbfs is locked. Patch for removal is sitting in my repository for almost a year. --SvH2i/6Q4qfAo9X5 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAkzYEuQACgkQC3+MBN1Mb4j9awCgjT/sNXF737obeLixZFmTJgZU mwwAoMXrnVc+Jxaoz0R9iXmeV0TKyDXn =5/2O -----END PGP SIGNATURE----- --SvH2i/6Q4qfAo9X5--
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