Re: [PATCH 0/4] Delayed ref root cleanups

[Boris Burkov <boris@bur.io>]

On Fri, Jan 09, 2026 at 06:17:39PM +0100, David Sterba wrote:
> Embed delayed root into btrfs_fs_info.

The patches all look fine to me, but I think it would be nice to give
some justification for why it is desirable to make this change besides
"it's possible". If anything, it is a regression on the size of struct
btrfs_fs_info as you mention in the first patch.

If the answer is just that it's simpler and there is no need for a
separate allocation, then fair enough. But then why not directly embed
all the one-off structures pointed to by fs_info? Like all the global
roots, for example. Are they too large? What constitutes too large?
Later, when we slowly add stuff to fs_info till it is bigger than 4k,
should we undo this patch set? Or look for other, bigger structs to
unembed first?

Thanks,
Boris

> 
> David Sterba (4):
>   btrfs: embed delayed root to struct btrfs_fs_info
>   btrfs: reorder members in btrfs_delayed_root for better packing
>   btrfs: don't use local variables for fs_info->delayed_root
>   btrfs: pass btrfs_fs_info to btrfs_first_delayed_node()
> 
>  fs/btrfs/delayed-inode.c | 49 +++++++++++++---------------------------
>  fs/btrfs/delayed-inode.h | 15 ------------
>  fs/btrfs/disk-io.c       |  8 ++-----
>  fs/btrfs/fs.h            | 18 +++++++++++++--
>  4 files changed, 34 insertions(+), 56 deletions(-)
> 
> -- 
> 2.51.1
>