Date: Mon, 16 May 2011 19:58:35 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: FreeBSD FS <freebsd-fs@freebsd.org> Subject: RFC: adding a lock flags argument to VFS_FHTOVP() for FreeBSD9 Message-ID: <256284561.428250.1305590315172.JavaMail.root@erie.cs.uoguelph.ca>
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Hi, Down the road, I would like the NFS server to be able to do a VFS_FHTOVP(mp, &fhp->fh_fid, LK_SHARED, vpp); similar to what is already supported for VFS_VGET(). The reason is that, currently, when a client does read-aheads, these reads are basically serialized because the VFS_FHTOVP() gets an LK_EXCLUSIVE locked vnode for each RPC on the server. Like VFS_VGET(), the underlying file system can still choose to return a LK_EXCLUSIVE locked vnode even when LK_SHARED is specified. (Some file systems, such as FFS, just call VFS_VGET() in VFS_FHTOVP(), so all that happens is that the flag is passed through to VFS_VGET() for those ones.) To minimize the risk of the patch breaking something, I have it setting LK_EXCLUSIVE for all VFS_FHTOVP() calls so that the semantics don't actually change. (Changing the NFS server to use LK_SHARED is a trivial patch, but will need extensive testing, so I'm not planning on that change for 9.0.) If you are interested, my current patch is at: http://people.freebsd.org/~rmacklem/fhtovp.patch So, does this sound like a reasonable thing to commit, once the patch is reviewed? rick
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