Commit 7c8d3a42 authored Jul 20, 2012 by Mikulas Patocka Committed by Alasdair G Kergon Jul 20, 2012

dm raid1: set discard_zeroes_data_unsupported



We can't guarantee that REQ_DISCARD on dm-mirror zeroes the data even if
the underlying disks support zero on discard.  So this patch sets
ti->discard_zeroes_data_unsupported.

For example, if the mirror is in the process of resynchronizing, it may
happen that kcopyd reads a piece of data, then discard is sent on the
same area and then kcopyd writes the piece of data to another leg.
Consequently, the data is not zeroed.

The flag was made available by commit 983c7db3
(dm crypt: always disable discard_zeroes_data).

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

parent 650d2a06

drivers/md/dm-raid1.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1084,6 +1084,7 @@ static int mirror_ctr(struct dm_target ti, unsigned int argc, char *argv)
		ti->split_io = dm_rh_get_region_size(ms->rh);
		ti->num_flush_requests = 1;
		ti->num_discard_requests = 1;
		ti->discard_zeroes_data_unsupported = 1;

		ms->kmirrord_wq = alloc_workqueue("kmirrord",
		WQ_NON_REENTRANT \| WQ_MEM_RECLAIM, 0);

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