Re: [PATCH 1/4] xfs: split up xfs_buf_alloc_backing_mem

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Jun 17, 2026 at 07:58:02AM +0200, Christoph Hellwig wrote:
> Split out helpers for folio and vmalloc allocations to prepare for a bug
> fix.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Ok, a simple hoist; so far so good

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_buf.c | 61 +++++++++++++++++++++++++++++++-----------------
>  1 file changed, 40 insertions(+), 21 deletions(-)
> 
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 0cea458f1353..d3d44e3ff001 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -120,6 +120,22 @@ xfs_buf_free(
>  	call_rcu(&bp->b_rcu, xfs_buf_free_callback);
>  }
>  
> +static int
> +xfs_buf_alloc_folio(
> +	struct xfs_buf		*bp,
> +	size_t			size,
> +	gfp_t			gfp_mask)
> +{
> +	struct folio		*folio;
> +
> +	folio = folio_alloc(gfp_mask, get_order(size));
> +	if (!folio)
> +		return -ENOMEM;
> +	bp->b_addr = folio_address(folio);
> +	trace_xfs_buf_backing_folio(bp, _RET_IP_);
> +	return 0;
> +}
> +
>  static int
>  xfs_buf_alloc_kmem(
>  	struct xfs_buf		*bp,
> @@ -148,6 +164,27 @@ xfs_buf_alloc_kmem(
>  	return 0;
>  }
>  
> +static int
> +xfs_buf_alloc_vmalloc(
> +	struct xfs_buf		*bp,
> +	size_t			size,
> +	gfp_t			gfp_mask,
> +	xfs_buf_flags_t		flags)
> +{
> +	for (;;) {
> +		bp->b_addr = __vmalloc(size, gfp_mask);
> +		if (bp->b_addr)
> +			break;
> +		if (flags & XBF_READ_AHEAD)
> +			return -ENOMEM;
> +		XFS_STATS_INC(bp->b_mount, xb_page_retries);
> +		memalloc_retry_wait(gfp_mask);
> +	}
> +
> +	trace_xfs_buf_backing_vmalloc(bp, _RET_IP_);
> +	return 0;
> +}
> +
>  /*
>   * Allocate backing memory for a buffer.
>   *
> @@ -175,7 +212,6 @@ xfs_buf_alloc_backing_mem(
>  {
>  	size_t		size = BBTOB(bp->b_length);
>  	gfp_t		gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOWARN;
> -	struct folio	*folio;
>  
>  	if (xfs_buftarg_is_mem(bp->b_target))
>  		return xmbuf_map_backing_mem(bp);
> @@ -216,33 +252,16 @@ xfs_buf_alloc_backing_mem(
>  	 */
>  	if (size > PAGE_SIZE) {
>  		if (!is_power_of_2(size))
> -			goto fallback;
> +			return xfs_buf_alloc_vmalloc(bp, size, gfp_mask, flags);
>  		gfp_mask &= ~__GFP_DIRECT_RECLAIM;
>  		gfp_mask |= __GFP_NORETRY;
>  	}
> -	folio = folio_alloc(gfp_mask, get_order(size));
> -	if (!folio) {
> +	if (xfs_buf_alloc_folio(bp, size, gfp_mask) < 0) {
>  		if (size <= PAGE_SIZE)
>  			return -ENOMEM;
>  		trace_xfs_buf_backing_fallback(bp, _RET_IP_);
> -		goto fallback;
> -	}
> -	bp->b_addr = folio_address(folio);
> -	trace_xfs_buf_backing_folio(bp, _RET_IP_);
> -	return 0;
> -
> -fallback:
> -	for (;;) {
> -		bp->b_addr = __vmalloc(size, gfp_mask);
> -		if (bp->b_addr)
> -			break;
> -		if (flags & XBF_READ_AHEAD)
> -			return -ENOMEM;
> -		XFS_STATS_INC(bp->b_mount, xb_page_retries);
> -		memalloc_retry_wait(gfp_mask);
> +		return xfs_buf_alloc_vmalloc(bp, size, gfp_mask, flags);
>  	}
> -
> -	trace_xfs_buf_backing_vmalloc(bp, _RET_IP_);
>  	return 0;
>  }
>  
> -- 
> 2.53.0
> 
>