Date: Thu, 17 Jan 2008 15:08:36 -0500 From: Adam <urbansnap@gmail.com> To: David Schultz <das@FreeBSD.ORG> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Reading and Writing to Block from di_spare Message-ID: <B0EF8F15-0B65-4C3B-98A0-FADBA4640EED@gmail.com> In-Reply-To: <20080117194457.GA84887@VARK.MIT.EDU> References: <485228D5-8D0B-4CD5-9FB7-B0D551B172DA@gmail.com> <20080117194457.GA84887@VARK.MIT.EDU>
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David, I understand that there is no routine to read and write specifically to an address contained in the di_spare. I also understand that di_spare is currently unused and has no specific manipulators. Allow me to clarify. I am looking for a way to take a ufs2_daddr_t (which is neither a direct nor indirect block of a di_node) and read/ write to that address. Regards, Adam On Jan 17, 2008, at 2:44 PM, David Schultz wrote: > On Thu, Jan 17, 2008, Adam wrote: >> Hi, I am working on a project for where I want to take the standard >> UFS/FFS file system that BSD ships with and add several blocks of >> information to the dinode. The simplest way of doing it seemed to be >> to allocate blocks to di_spare. I believe that I have figured out >> how >> to do that: >> >> ffs_alloc(inode, 0 , 0, (int)(inode->i_fs->fs_bsize), td->td_ucred, >> &addr); >> dinode->di_spare[1]=(int64_t)addr; >> >> I'm having problems taking that block address and reading/writing to >> it. As far as I can tell most of the buffer read routines (getblk, >> bread) seem to be geared toward reading and writing direct and >> indirect blocks in an inode. >> >> How do I read and write a block that is neither a direct nor an >> indirect block? > > Maybe I'm misunderstanding your question, but I don't see how you > could expect FreeBSD to have routines to read and write things > that don't exist in FreeBSD. :) > > See extattr(2). It may be possible that the "extra information" > you want to store with files can be stored in user space using the > relatively standard extended attributes API.
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