On 03/01/2016 03:43 PM, Bart Van Assche wrote:
After having run multipath -f + another reconfigure I noticed that the
optimal_io_size parameter for multipath devices is zero (io_opt) but
that blk_stack_limits() expects that that parameter is not zero. So i
tried to repeat the test described in commit
e9637415a92cf25ad800b7fdeddcd30cce7b44ab:
# modprobe scsi_debug dev_size_mb=10 num_tgts=1 opt_blks=1536
# lsscsi | grep debug
[17352:0:0:0]disk Linux scsi_debug 0184 /dev/sds
# cat /sys/block/sds/queue/optimal_io_size
1536
# dmsetup create node --table "0 100 linear /dev/sds 0"
(hangs in the semop() system call)
^C
(again replying to my own e-mail)
Apparently this works fine with kernel v4.5-rc6:
# modprobe scsi_debug dev_size_mb=10 num_tgts=1 opt_blks=1536
# lsscsi | grep debug
[42:0:0:0] disk Linux scsi_debug 0184 /dev/sdai
# cat /sys/block/sdai/queue/optimal_io_size
786432
# dmsetup create node --table "0 100 linear /dev/sdai 0"
# dmsetup table | grep linear
node: 0 100 linear 66:32 0
# dmsetup ls | grep node
node (254:2)
# cat /sys/block/dm-2/queue/optimal_io_size
786432
I will report this to the proper bugzilla. Sorry for the noise.
Bart.
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