From: NeilBrown <neilb@suse.com>
Date: Fri, 24 Jul 2015 03:30:32 +0000 (+1000)
Subject: md/raid5: handle possible race as reshape completes.
X-Git-Tag: omap-for-v4.3/fixes-rc1~84^2~19
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6cbd81487f7cfa30e22537bf7cd07f48c4e7164d;p=pandora-kernel.git

md/raid5: handle possible race as reshape completes.

It is possible (though unlikely) for a reshape to be
interrupted between the time that end_reshape is called
and the time when raid5_finish_reshape is called.

This can leave conf->reshape_progress set to MaxSector,
but mddev->reshape_position not.

This combination confused reshape_request() when ->reshape_backwards.
As conf->reshape_progress is so high, it seems the reshape hasn't
really begun.  But assuming MaxSector is a valid address only
leads to sorrow.

So ensure reshape_position and reshape_progress both agree,
and add an extra check in reshape_request() just in case they don't.

Signed-off-by: NeilBrown <neilb@suse.com>
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