Commit 848b3182 authored by NeilBrown's avatar NeilBrown
Browse files

md: raid5: avoid sector values going negative when testing reshape progress. 



As sector_t in unsigned, we cannot afford to let 'safepos' etc go
negative.
So replace
   a -= b;
by
   a -= min(b,a);

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent b6a9ce68

drivers/md/raid5.c

+3 −3
Original line number Diff line number Diff line
@@ -3811,13 +3811,13 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped 
	safepos = conf->reshape_safe;

	sector_div(safepos, data_disks);

	if (mddev->delta_disks < 0) {

		writepos -= reshape_sectors;

		writepos -= min(reshape_sectors, writepos);

		readpos += reshape_sectors;

		safepos += reshape_sectors;

	} else {

		writepos += reshape_sectors;

		readpos -= reshape_sectors;

		safepos -= reshape_sectors;

		readpos -= min(reshape_sectors, readpos);

		safepos -= min(reshape_sectors, safepos);

	}



	/* 'writepos' is the most advanced device address we might write.

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