Date: Wed, 10 Nov 2010 23:41:29 +0300 From: Oleg Sharoyko <osharoiko@gmail.com> To: mjacob@freebsd.org, freebsd-geom@freebsd.org Subject: [patch] [geom_multipath] detached device used as an active path Message-ID: <AANLkTi=B2Gniv3RDmLexN8Br8W0Q4t=V_0A57XPkQe4g@mail.gmail.com>
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Hi Matthew,
Please take a look at the patch I'm attaching to this mail. It fixes
couple of issues with cp->active being left pointing to detached
device. I have as well tried to remove code duplication a bit by using
g_multipath_rotate() in g_mpd() and g_multipath_done_error() instead
of identical loops.
One thing which I'm not 100% sure about is this part (this is within
g_multipath_access()):
@@ -258,7 +268,7 @@
LIST_FOREACH(cp, &gp->consumer, consumer) {
error = g_access(cp, dr, dw, de);
- if (error) {
+ if (error && error != ENXIO) {
badcp = cp;
goto fail;
}
This change fixes undesired behavior in the following case:
While running
while true; do
echo
date
dd if=/dev/multipath/test of=/dev/null bs=512 count=1
sleep 1
done
disconnect currently active path of /dev/multipath/test.
Without "&& error != ENXIO" I have exactly one failed dd. Whith it -
none of dd fails.
Shouldn't the overall logic of g_multipath_access() be as follows: try
to do what we're asked to do while there are at least one available
path, and remove from g_multipath any path for which g_access() call
has failed? I would suppose that multipath device should try to work
as long as there is at least one workable path, and any path which has
failed (no matter if it was a physical failure or, f.e. ENOMEM in
device driver) should be detached from multipath device.
--
Oleg Sharoyko
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