On 12/21/20 10:49 PM, Naohiro Aota wrote:
In zoned btrfs a region that was once written then freed is not usable until we reset the underlying zone. So we need to distinguish such unusable space from usable free space. Therefore we need to introduce the "zone_unusable" field to the block group structure, and "bytes_zone_unusable" to the space_info structure to track the unusable space. Pinned bytes are always reclaimed to the unusable space. But, when an allocated region is returned before using e.g., the block group becomes read-only between allocation time and reservation time, we can safely return the region to the block group. For the situation, this commit introduces "btrfs_add_free_space_unused". This behaves the same as btrfs_add_free_space() on regular btrfs. On zoned btrfs, it rewinds the allocation offset. Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Thanks, Josef
