6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Naohiro Aota <naohiro.aota@xxxxxxx>
[ Upstream commit 02444f2ac26eae6385a65fcd66915084d15dffba ]
Writing sequentially to a huge file on btrfs on a SMR HDD revealed a
decline of the performance (220 MiB/s to 30 MiB/s after 500 minutes).
The performance goes down because of increased latency of the extent
allocation, which is induced by a traversing of a lot of full block groups.
So, this patch optimizes the ffe_ctl->hint_byte by choosing a block group
with sufficient size from the active block group list, which does not
contain full block groups.
After applying the patch, the performance is maintained well.
Fixes: 2eda57089ea3 ("btrfs: zoned: implement sequential extent allocation")
CC: stable@xxxxxxxxxxxxxxx # 5.15+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/btrfs/extent-tree.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 69abb6eb81df..b89b558b1592 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4152,6 +4152,24 @@ static int prepare_allocation_zoned(struct btrfs_fs_info *fs_info,
if (fs_info->data_reloc_bg)
ffe_ctl->hint_byte = fs_info->data_reloc_bg;
spin_unlock(&fs_info->relocation_bg_lock);
+ } else if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA) {
+ struct btrfs_block_group *block_group;
+
+ spin_lock(&fs_info->zone_active_bgs_lock);
+ list_for_each_entry(block_group, &fs_info->zone_active_bgs, active_bg_list) {
+ /*
+ * No lock is OK here because avail is monotinically
+ * decreasing, and this is just a hint.
+ */
+ u64 avail = block_group->zone_capacity - block_group->alloc_offset;
+
+ if (block_group_bits(block_group, ffe_ctl->flags) &&
+ avail >= ffe_ctl->num_bytes) {
+ ffe_ctl->hint_byte = block_group->start;
+ break;
+ }
+ }
+ spin_unlock(&fs_info->zone_active_bgs_lock);
}
return 0;
--
2.43.0
