[PATCH 2/2] btrfs-progs: Unify metadata chunk size with kernel

[Qu Wenruo]

Mkfs tends to create pretty large metadata chunk compared to kernel:
  Node size:          16384
  Sector size:        4096
  Filesystem size:    10.00GiB
  Block group profiles:
    Data:             single            8.00MiB
    Metadata:         DUP               1.00GiB
    System:           DUP               8.00MiB

While kernel only tends to create 256MiB metadata chunk:
                /* for larger filesystems, use larger metadata chunks */
                if (fs_devices->total_rw_bytes > 50ULL * SZ_1G)
                        max_stripe_size = SZ_1G;
                else
                        max_stripe_size = SZ_256M;

This won't cause problems in real world, but it's still better to make
the behavior unified.

Signed-off-by: Qu Wenruo <w...@suse.com>
---
 volumes.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/volumes.c b/volumes.c
index 2611a932c01c..3a91b43b378b 100644
--- a/volumes.c
+++ b/volumes.c
@@ -989,8 +989,12 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                        min_stripe_size = SZ_64M;
                        max_stripes = BTRFS_MAX_DEVS(info);
                } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
-                       calc_size = SZ_1G;
-                       max_chunk_size = 4 * calc_size;
+                       /* for larger filesystems, use larger metadata chunks */
+                       if (info->fs_devices->total_rw_bytes > 50ULL * SZ_1G)
+                               max_chunk_size = SZ_1G;
+                       else
+                               max_chunk_size = SZ_256M;
+                       calc_size = max_chunk_size;
                        min_stripe_size = SZ_32M;
                        max_stripes = BTRFS_MAX_DEVS(info);
                }
-- 
2.20.1