From: Alex Elder <elder@inktank.com>
Date: Tue, 30 Apr 2013 05:44:32 +0000 (-0500)
Subject: rbd: don't revalidate so much
X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~26^2~20
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a3fbe5d447bf1f63efa7f4d8c222002ef136cf4b;p=pandora-kernel.git

rbd: don't revalidate so much

Whenever a header object event causes a mapped rbd image to refresh
its header information, revalidate_disk() is being called.  This was
done in rbd_dev_refresh() outside the control mutex in order to
avoid a lock inversion.  Although a an event like this *might*
indicate the image has changed size, most of the time it does not.

Record the image size before and after the refresh, and only
call revalidate_disk() if it changes.

This resolves:
    http://tracker.ceph.com/issues/4867

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
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