ext3 htree brelse problems look to be fixed!

ext3 htree brelse problems look to be fixed!

[James H. Cloos Jr.]

I just booted 2.5-bk current as of last night with the below patch¹
(which was recently posted to ext3-users) that un-static-ifies a 
struct dx_frame in namei.c.

I then did my best torture test for the brelse bug:  starting gnus
(3600+ nnmh folders² with a total of XXX messages; it does a readdir
on each of those folders) while doing bk consistancy checks in 2.5
and/or 2.4 kernel trees.  All while fetchmail+procmail+spamd processes
a stream of incoming mail.

That load had never failed to generate a brelse in the syslog; each
occurance of brelse in the syslog correlated to a short readdir.  In
gnus the short readdir would result in temporarily missing mail; in bk
the consistancy check would fail.  If the bk check was the result of a
pull, a manual bk resync would be required to fix the tree.  (Or one
could remove the RESYNC and PENDING dirs and re-pull.)

The bug did not occur during the torture test.  Even with three bk
checks in parallel (2.5 current, 2.4 current and a clone of a clone of
2.5 as of yesterday.)

I beleive (with this patch) htree is now ready for prime time.

-JimC

² one message per file in seq(1) order, ala old-style usenet spools

¹ the patch as posted by Andreas Dilger <adilger@clusterfs.com> is:

===== namei.c 1.15 vs edited =====
--- 1.15/fs/ext3/namei.c        Wed Oct  2 01:24:11 2002
+++ edited/namei.c      Sun Mar  2 00:05:03 2003
@@ -530,7 +530,7 @@
        struct dx_hash_info hinfo;
        struct buffer_head *bh;
        struct ext3_dir_entry_2 *de, *top;
-       static struct dx_frame frames[2], *frame;
+       struct dx_frame frames[2], *frame;
        struct inode *dir;
        int block, err;
        int count = 0;

Re: ext3 htree brelse problems look to be fixed!

[James H. Cloos Jr.]

>>>>> "Daniel" == Daniel Phillips <phillips@arcor.de> writes:

Daniel> Good that it's working for you, but it's not quite the last
Daniel> issue.  There is some apparent cache thrashing to track down,
Daniel> and I believe there's still an outstanding NFS issue.

Yes, I forgot about nfs.  But at least, ignoring nfs again, corruption
type issues seem to be fixed.

I guess my post was a bit exuberant....  :-/

-jimc

Re: ext3 htree brelse problems look to be fixed!

[Daniel Phillips]

On Wed 05 Mar 03 00:57, James H. Cloos Jr. wrote:
> I beleive (with this patch) htree is now ready for prime time.

Good that it's working for you, but it's not quite the last issue.  There is 
some apparent cache thrashing to track down, and I believe there's still an 
outstanding NFS issue.  It's getting there, though.

Regards,

Daniel

Re: ext3 htree brelse problems look to be fixed!

[Bill Davidsen]

On Wed, 5 Mar 2003, Daniel Phillips wrote:

> On Wed 05 Mar 03 00:57, James H. Cloos Jr. wrote:
> > I beleive (with this patch) htree is now ready for prime time.
> 
> Good that it's working for you, but it's not quite the last issue.  There is 
> some apparent cache thrashing to track down, and I believe there's still an 
> outstanding NFS issue.  It's getting there, though.

Well, if that's the last issue causing corruption of one kind or another,
I would say that it's a huge step forward. Performance is desirable,
reliability is manditory.

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.