xfs
[Top] [All Lists]

Re: write back cache and barriers

To: Martin Steigerwald <Martin@xxxxxxxxxxxx>
Subject: Re: write back cache and barriers
From: Eric Sandeen <sandeen@xxxxxxxxxxx>
Date: Sun, 06 Aug 2006 21:31:54 -0500
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <200608061100.36508.Martin@lichtvoll.de>
References: <5545990.post@talk.nabble.com> <44CC2D1A.3060805@sandeen.net> <200608061100.36508.Martin@lichtvoll.de>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Thunderbird 1.5.0.5 (Macintosh/20060719)
Martin Steigerwald wrote:

Hello Eric,

for my article I looked at the source code of those. It seems that journal block device tests wether barriers work

commit.c:       if (ret == -EOPNOTSUPP && barrier_done) {
commit.c:                       "JBD: barrier-based sync failed on %s - "
commit.c:                       "disabling barriers\n",

Also reiserfs 3 seems to deactivate barriers if not avaible (journal.c)

if (reiserfs_barrier_flush(p_s_sb)) {
int ret;
lock_buffer(journal->j_header_bh);
ret = submit_barrier_buffer(journal->j_header_bh);
if (ret == -EOPNOTSUPP) {
set_buffer_uptodate(journal->j_header_bh);
disable_barrier(p_s_sb);
goto sync;
}
wait_on_buffer(journal->j_header_bh);
check_barrier_completion(p_s_sb, journal->j_header_bh);
} else {


(both sources from kernel 2.6.17.7)

Yep, you're right, not quite sure how I missed that...

Thanks,

-Eric


<Prev in Thread] Current Thread [Next in Thread>