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