On 12/21/20 10:48 PM, Naohiro Aota wrote:

This is preparation patch to implement zone emulation on a regular device.

To emulate zoned mode on a regular (non-zoned) device, we need to decide an
emulating zone size. Instead of making it compile-time static value, we'll
make it configurable at mkfs time. Since we have one zone == one device
extent restriction, we can determine the emulated zone size from the size
of a device extent. We can extend btrfs_get_dev_zone_info() to show a
regular device filled with conventional zones once the zone size is
decided.

The current call site of btrfs_get_dev_zone_info() during the mount process
is earlier than reading the trees, so we can't slice a regular device to
conventional zones. This patch defers the loading of zone info to
open_ctree() to load the emulated zone size from a device extent.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef