From owner-freebsd-hackers Mon Aug 10 14:47:16 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id OAA05749 for freebsd-hackers-outgoing; Mon, 10 Aug 1998 14:47:16 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from lor.watermarkgroup.com (lor.watermarkgroup.com [207.202.73.33]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id OAA05744 for ; Mon, 10 Aug 1998 14:47:12 -0700 (PDT) (envelope-from luoqi@watermarkgroup.com) Received: (from luoqi@localhost) by lor.watermarkgroup.com (8.8.8/8.8.8) id RAA23316; Mon, 10 Aug 1998 17:46:19 -0400 (EDT) (envelope-from luoqi) Date: Mon, 10 Aug 1998 17:46:19 -0400 (EDT) From: Luoqi Chen Message-Id: <199808102146.RAA23316@lor.watermarkgroup.com> To: bf20761@binghamton.edu, freebsd-hackers@FreeBSD.ORG Subject: Re: Question about routine getblk() Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > Hi, getblk() tries to get a buffer with specified size > of physical memory allocated to it. I got two questions > about this routine: > > (1) The given size could be greater than the optimial size contained in > the mount structure. The comment says "this happens on mount points". > Why is the case? The size you were talking about was the block size of the file system, it is used to translate starting blkno to a vm offset. For a mount point covered by another file system, the correct block size should be coming from the fs that is covering this vnode, but vp->v_mount still points to the fs being covered, and block size for these two fs could be different. > > (2) If the buffer is in the core, we check for size inconsistancies. Why > should this happen and why should we be conservative on metadata. I'm not sure about this one. Maybe it happens when a frag is extended to a full block? > > Any help is appreciated. > > > -------------------------------------------------- > | Zhihui Zhang, http://cs.binghamton.edu/~zzhang | > | Dept. of Computer Science, SUNY at Binghamton | > -------------------------------------------------- > -lq To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message