bcachefs format device specific options are inherited by later devices

[freswa]

bcachefs format --label hdd.hdd0 /dev/mapper/hdd0 --label=ssd.ssd0 --discard --durability=2 /dev/mapper/ssd0

Gives me hdd0 with durability 1 and discard disabled.

bcachefs format --label=ssd.ssd0 --discard --durability=2 /dev/mapper/ssd0 --label hdd.hdd0 /dev/mapper/hdd0

Gives me hdd0 with durability 2 and discard enabled.

If intentional, we need to document this behavior.

[daurnimator]

Looks like dev_opts is not completely reset in

bcachefs-tools/c_src/cmd_format.c

Line 211 in 78e7511

dev_opts.size = 0;

I think it should be replaced with

    dev_opts = dev_opts_default();