From: Konrad Rzeszutek Wilk Date: Mon, 10 Oct 2011 04:42:22 +0000 (-0400) Subject: xen/blkback: Support 'feature-barrier' aka old-style BARRIER requests. X-Git-Tag: v3.2-rc1~48^2~3^2~4 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=29bde093787f3bdf7b9b4270ada6be7c8076e36b;p=pandora-kernel.git xen/blkback: Support 'feature-barrier' aka old-style BARRIER requests. We emulate the barrier requests by draining the outstanding bio's and then sending the WRITE_FLUSH command. To drain the I/Os we use the refcnt that is used during disconnect to wait for all the I/Os before disconnecting from the frontend. We latch on its value and if it reaches either the threshold for disconnect or when there are no more outstanding I/Os, then we have drained all I/Os. Suggested-by: Christopher Hellwig Signed-off-by: Konrad Rzeszutek Wilk --- Reading git-diff-tree failed