Journalled UFS
Pawel Jakub Dawidek
pjd at FreeBSD.org
Fri May 21 09:09:16 PDT 2004
On Fri, May 14, 2004 at 01:46:11PM -0400, David E. Cross wrote:
+> Ok... It was brought to my attention that someone was asking for this
+> again, so I figure its time to put out an update on the status.
Great to hear!
+> Here's what I want to do:
+>
+> VOP/VFS entry point {
+> Aquire Mutex with RECURSION;
mtx_lock(your_mtx);
+> If first aquire, inc transaction ID; else don't;
if (!mtx_recursed(your_mtx))
/* Inc transaction ID. */;
+> NORMAL VOP/VFS Dispatch;
+>
+> Release Mutex;
recursed = mtx_recursed(your_mtx);
mtx_unlock(your_mtx);
+> if last release && syn_journal Checkpoint_Routine;
if (!recursed && syn_journal)
Checkpoint_Routine;
+> }
+> Checkpoint_Routine {
+> Aquire mutex with RECURSION:
+> if first aquire, last_tid=TID;
+> else last_tid=TID-1;
+>
+> Dump_to last_tid;
+>
+> Release mutex;
+> }
+>
+> I am not sure how to check if we already have a mutex, and if its
+> recursion or not vs. the mutex is already aquired but its not "ours".
+> suggestions?
I'm not sure why you want to check if mutex is already acquired.
You don't want to sleep? You can use mtx_trylock(9) or mtx_owned(9) maybe.
--
Pawel Jakub Dawidek http://www.FreeBSD.org
pjd at FreeBSD.org http://garage.freebsd.pl
FreeBSD committer Am I Evil? Yes, I Am!
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