Subject: Re: linux-next: manual merge of the btrfs tree with the btrfs-fixes tree

From: Stephen Rothwell <[email-masked]>
Date: Fri, 1 May 2020 11:05:58 +1000

Hi all,

On Fri, 1 May 2020 10:24:53 +1000 Stephen Rothwell <[email-masked]> wrote:
>
> Today's linux-next merge of the btrfs tree got a conflict in:
> 
>   fs/btrfs/transaction.c
> 
> between commit:
> 
>   fcc99734d1d4 ("btrfs: transaction: Avoid deadlock due to bad initialization timing of fs_info::journal_info")
> 
> from the btrfs-fixes tree and commit:
> 
>   f12ca53a6fd6 ("btrfs: force chunk allocation if our global rsv is larger than metadata")
> 
> from the btrfs tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> -- 
> Cheers,
> Stephen Rothwell
> 
> diff --cc fs/btrfs/transaction.c
> index 2d5498136e5e,e4dbd8e3c641..000000000000
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@@ -666,15 -674,17 +672,26 @@@ got_it
>   		current->journal_info = h;
>   
>   	/*
>  +	 * btrfs_record_root_in_trans() needs to alloc new extents, and may
>  +	 * call btrfs_join_transaction() while we're also starting a
>  +	 * transaction.
>  +	 *
>  +	 * Thus it need to be called after current->journal_info initialized,
>  +	 * or we can deadlock.
>  +	 */
>  +	btrfs_record_root_in_trans(h, root);
>  +
> + 	 * If the space_info is marked ALLOC_FORCE then we'll get upgraded to
> + 	 * ALLOC_FORCE the first run through, and then we won't allocate for
> + 	 * anybody else who races in later.  We don't care about the return
> + 	 * value here.
> + 	 */
> + 	if (do_chunk_alloc && num_bytes) {
> + 		u64 flags = h->block_rsv->space_info->flags;
> + 		btrfs_chunk_alloc(h, btrfs_get_alloc_profile(fs_info, flags),
> + 				  CHUNK_ALLOC_NO_FORCE);
> + 	}
> + 
>   	return h;
>   
>   join_fail:

I fixed the missing comment start in my resolution ...
-- 
Cheers,
Stephen Rothwell