lightnvm: pblk: set conservative threshold for user writes

In a worst-case scenario (random writes), OP% of sectors
in each line will be invalid, and we will then need
to move data out of 100/OP% lines to free a single line.

So, to prevent the possibility of running out of lines,
temporarily block user writes when there is less than
100/OP% free lines.

Also ensure that pblk creation does not produce instances
with insufficient over provisioning.

Insufficient over-provising is not a problem on real hardware,
but often an issue when running QEMU simulations (with few lines).
100 lines is enough to create a sane instance with the standard
(11%) over provisioning.

Signed-off-by: Hans Holmberg <[email protected]>
Reviewed-by: Javier González <[email protected]>
Signed-off-by: Matias Bjørling <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions