On 12/21/20 10:49 PM, Naohiro Aota wrote:

This is 3/4 patch to implement device-replace on ZONED mode.

This commit implement copying. So, it track the write pointer during device
replace process. Device-replace's copying is smart to copy only used
extents on source device, we have to fill the gap to honor the sequential
write rule in the target device.

Device-replace process in ZONED mode must copy or clone all the extents in
the source device exactly once.  So, we need to use to ensure allocations
started just before the dev-replace process to have their corresponding
extent information in the B-trees. finish_extent_writes_for_zoned()
implements that functionality, which basically is the removed code in the
commit 042528f8d840 ("Btrfs: fix block group remaining RO forever after
error during device replace").

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

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

Thanks,

Josef