>>>>> "Mike" == Mike Snitzer <snitzer@xxxxxxxxxx> writes:
>> However, there are other subsystems that need to stack without an
>> associated block_device. So instead of changing blk_stack_limits I
>> propose we use the wrapper below.
Mike> Yes, looks like osdblk.c's use of blk_queue_stack_limits()
DM also does a stacking pass without a bdev (dm_calculate_queue_limits),
although I think you can avoid that by getting rid of ti_limits
altogether and just stack limits.
I couldn't figure out why the alignment_offset for a misaligned DM
device was zero, despite being -1 after stacking had completed. I
finally spotted this in dm_table_set_restrictions():
limits->alignment_offset = 0;
limits->misaligned = 0;
So after all the stacking function's hard work you set the alignment to
0 and clear the misaligned flag. Why?
--
Martin K. Petersen Oracle Linux Engineering
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