On Tue, Nov 24, 2020 at 07:36:18PM +0800, Anand Jain wrote:
On 10/11/20 7:26 pm, Naohiro Aota wrote:
This commit implements a zoned chunk/dev_extent allocator. The zoned
allocator aligns the device extents to zone boundaries, so that a zone
reset affects only the device extent and does not change the state of
blocks in the neighbor device extents.
Also, it checks that a region allocation is not overlapping any of the
super block zones, and ensures the region is empty.
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
Looks good.
Chunks and stripes are aligned to the zone_size. I guess zone_size won't
change after the block device has been formatted with it? For testing,
what if the device image is dumped onto another zoned device with a
different zone_size?
Zone size is a drive characteristic, so it never change on the same device.
Dump/restore on another device with a different zone_size should be banned,
because we cannot ensure device extents are aligned to zone boundaries.
A small nit is below.
+static void init_alloc_chunk_ctl_policy_zoned(
+ struct btrfs_fs_devices *fs_devices,
+ struct alloc_chunk_ctl *ctl)
+{
+ u64 zone_size = fs_devices->fs_info->zone_size;
+ u64 limit;
+ int min_num_stripes = ctl->devs_min * ctl->dev_stripes;
+ int min_data_stripes = (min_num_stripes - ctl->nparity) / ctl->ncopies;
+ u64 min_chunk_size = min_data_stripes * zone_size;
+ u64 type = ctl->type;
+
+ ctl->max_stripe_size = zone_size;
+ if (type & BTRFS_BLOCK_GROUP_DATA) {
+ ctl->max_chunk_size = round_down(BTRFS_MAX_DATA_CHUNK_SIZE,
+ zone_size);
+ } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
+ ctl->max_chunk_size = ctl->max_stripe_size;
+ } else if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
+ ctl->max_chunk_size = 2 * ctl->max_stripe_size;
+ ctl->devs_max = min_t(int, ctl->devs_max,
+ BTRFS_MAX_DEVS_SYS_CHUNK);
+ }
+
+ /* We don't want a chunk larger than 10% of writable space */
+ limit = max(round_down(div_factor(fs_devices->total_rw_bytes, 1),
What's the purpose of dev_factor here?
This one follows the same limitation as in regular allocator
(init_alloc_chunk_ctl_policy_regular).
Thanks.
