Please ignore the second question. I thought KKASSERT was doing things
the other way around :)
Thanks,
Rongsheng
On Tue, Mar 08, 2005 at 12:47:05PM -0500, Rongsheng Fang wrote:
> Date: Tue, 8 Mar 2005 12:47:05 -0500
> From: Rongsheng Fang <rfang@coke.umuc.edu>
> To: kernel@crater.dragonflybsd.org
> Subject: vfs_journal.c code questions
> Mail-Followup-To: Rongsheng Fang <rfang@coke.umuc.edu>,
> kernel@crater.dragonflybsd.org
> Message-Id: <20050308174705.GB29199@coke.umuc.edu>
>
> I was reading through the vfs_journal.c code and was confused by some
> of the code:
>
> /usr/src/sys/kern/vfs_journal.c
>
> In function journal_install_vfs_journal()
>
> ...
> jrecord_init(jo, &jrec, JREC_STREAMID_DISCONT);
> jrecord_write(&jrec, JTYPE_ASSOCIATE, 0);
> ...
>
>
> 1) the `streamid' parameter for jrecord_init() is set to
> JREC_STREAMID_DISCONT which is defined as 0x0002.
>
> While in function jrecord_init():
>
> ...
> if (streamid < 0) {
> streamid = sid++; /* XXX need to track stream ids! */
> if (sid == JREC_STREAMID_JMAX)
> sid = JREC_STREAMID_JMIN;
> }
> jrec->streamid = streamid;
> ...
>
> So now jrec->streamid is JREC_STREAMID_DISCONT (0x0002).
>
> Shouldn't streamid be some number between JREC_STREAMID_JMIN and
> JREC_STREAMID_JMAX?
>
> #define JREC_STREAMID_JMIN 0x0100 /* lowest allowed general id */
> #define JREC_STREAMID_JMAX 0x2000 /* (one past the highest allowed id) */
>
> 2) then jrecord_write() comes right after jrecord_init() (also in
> function journal_install_vfs_journal()):
>
> jrecord_write(&jrec, JTYPE_ASSOCIATE, 0);
>
> In function jrecord_write():
>
> /*
> * Try to catch some obvious errors. Nesting records must specify a
> * size of 0, and there should be no left-overs from previous operations
> * (such as incomplete data writeouts).
> */
> KKASSERT(bytes == 0 || (rectype & JMASK_NESTED) == 0);
> KKASSERT(jrec->residual == 0);
>
> Then the kernel is going to panic? Actually it's not in practice, so
> I am a bit confused :(
>
> Thanks,
>
> Rongsheng
>
> !DSPAM:422de5af1814491114!