Re: [PATCH 1/4] xfs: bump up reserved blocks in xfs_alloc_set_aside

[Brian Foster <bfoster@redhat.com>]

On Mon, Jan 09, 2017 at 08:53:39PM +0100, Christoph Hellwig wrote:
> Setting aside 4 blocks globally for bmbt splits isn't all that useful,
> as different threads can allocate space in parallel.  Bump it to 4
> blocks per AG to allow each thread that is currently doing an
> allocation to dip into it separately.  Without that we may no have
> enough reserved blocks if there are enough parallel transactions
> in an almost out space file system that all run into bmap btree
> splits.
> 

Thanks.

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_alloc.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 5050056..0a46f84 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -95,10 +95,7 @@ unsigned int
>  xfs_alloc_set_aside(
>  	struct xfs_mount	*mp)
>  {
> -	unsigned int		blocks;
> -
> -	blocks = 4 + (mp->m_sb.sb_agcount * XFS_ALLOC_AGFL_RESERVE);
> -	return blocks;
> +	return mp->m_sb.sb_agcount * (XFS_ALLOC_AGFL_RESERVE + 4);
>  }
>  
>  /*
> -- 
> 2.1.4
> 
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