The skd driver has never handled discards reliably.
The kernel will BUG as a result of issuing discards to the skd device.
Disable the skd driver's discard support until it is proven reliable.
The device-mapper-test-suite test that exposed this bug just issues a
discard that covers a portion of the skd device that was previously
written through a dm-thin device. The discard spans the entire 1GB thin
device (logical sector 0 through 2097152).
dmtest run --profile stec --suite thin-provisioning -n
/discard_fully_provisioned_device/
associated device-mapper-test-suite ruby test code follows:
def test_discard_fully_provisioned_device
with_standard_pool(@size) do |pool|
with_new_thins(pool, @volume_size, 0, 1) do |thin, thin2|
wipe_device(thin)
wipe_device(thin2)
assert_used_blocks(pool, 2 * @blocks_per_dev)
thin.discard(0, @volume_size)
assert_used_blocks(pool, @blocks_per_dev)
end
end
...
Signed-off-by: Mike Snitzer <snit...@redhat.com>
---
drivers/block/skd_main.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/block/skd_main.c b/drivers/block/skd_main.c
index eb6e1e0..5dadecc 100644
--- a/drivers/block/skd_main.c
+++ b/drivers/block/skd_main.c
@@ -4441,12 +4441,15 @@ static int skd_cons_disk(struct skd_device *skdev)
/* set sysfs ptimal_io_size to 8K */
blk_queue_io_opt(q, 8192);
+#if 0
+ /* FIXME: Disable discard support until it no longer BUGs */
/* DISCARD Flag initialization. */
q->limits.discard_granularity = 8192;
q->limits.discard_alignment = 0;
q->limits.max_discard_sectors = UINT_MAX >> 9;
q->limits.discard_zeroes_data = 1;
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+#endif
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
spin_lock_irqsave(&skdev->lock, flags);
--
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