Date: Mon, 8 Nov 2010 10:04:59 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-fs@freebsd.org Cc: Ivan Voras <ivoras@freebsd.org> Subject: Re: The state of Giant lock in the file systems? Message-ID: <201011081004.59640.jhb@freebsd.org> In-Reply-To: <ib8qda$nat$1@dough.gmane.org> References: <ib8qda$nat$1@dough.gmane.org>
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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. > > 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" instances: > > 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 > > Except for these, is there any more magic that would need to be resolved > to excise Giant from VFS? > > Would it be correct to think that coda is the single biggest obstacle? Err, all the VFS_LOCK_GIANT() stuff for filesystems that do not have MNTK_MPSAFE set. I believe the currently MPSAFE fs's are UFS, ZFS, MSDOSFS, CD9660, UDF, NFS client, and devfs. I think all others are !MPSAFE still. -- John Baldwin
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