From: Mike Snitzer Date: Tue, 2 Aug 2011 11:32:08 +0000 (+0100) Subject: dm table: set flush capability based on underlying devices X-Git-Tag: v3.1-rc1~85^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed8b752bccf2560e305e25125721d2f0ac759e88;p=pandora-kernel.git dm table: set flush capability based on underlying devices DM has always advertised both REQ_FLUSH and REQ_FUA flush capabilities regardless of whether or not a given DM device's underlying devices also advertised a need for them. Block's flush-merge changes from 2.6.39 have proven to be more costly for DM devices. Performance regressions have been reported even when DM's underlying devices do not advertise that they have a write cache. Fix the performance regressions by configuring a DM device's flushing capabilities based on those of the underlying devices' capabilities. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- Reading git-diff-tree failed