[Cluster-devel] [GFS2 PATCH] GFS2: Fall back to vmalloc if kmalloc fails for dir hash tables

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

On Thu, 2013-05-30 at 09:08 -0400, Bob Peterson wrote:
> Hi,
> 
> When GFS2's directory management code allocates buffers for a
> directory hash table, if it can't get the memory it needs, it
> currently gives an bad return code. Rather than giving an error,
> this patch allows it to use virtual memory rather than kernel
> memory for the hash table. This should make it possible for
> directories to function properly, even when kernel memory becomes
> very fragmented.
> 
> Regards,
> 
> Bob Peterson
> Red Hat File Systems
> 
> Signed-off-by: Bob Peterson <rpeterso@redhat.com> 
> ---
> diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
> index c3e82bd..cf662fd 100644
> --- a/fs/gfs2/dir.c
> +++ b/fs/gfs2/dir.c
> @@ -355,21 +355,30 @@ static __be64 *gfs2_dir_get_hash_table(struct gfs2_inode *ip)
>  	}
>  
>  	hc = kmalloc(hsize, GFP_NOFS);
This should have GFP_NOWARN in addition to GFP_NOFS I think. Otherwise
looks good,

Steve.

> -	ret = -ENOMEM;
> +	if (hc == NULL)
> +		hc = vmalloc(hsize);
> +
>  	if (hc == NULL)
>  		return ERR_PTR(-ENOMEM);
>  
>  	ret = gfs2_dir_read_data(ip, hc, hsize);
>  	if (ret < 0) {
> -		kfree(hc);
> +		if (is_vmalloc_addr(hc))
> +			vfree(hc);
> +		else
> +			kfree(hc);
>  		return ERR_PTR(ret);
>  	}
>  
>  	spin_lock(&inode->i_lock);
> -	if (ip->i_hash_cache)
> -		kfree(hc);
> -	else
> +	if (ip->i_hash_cache) {
> +		if (is_vmalloc_addr(hc))
> +			vfree(hc);
> +		else
> +			kfree(hc);
> +	} else {
>  		ip->i_hash_cache = hc;
> +	}
>  	spin_unlock(&inode->i_lock);
>  
>  	return ip->i_hash_cache;
> @@ -385,7 +394,10 @@ void gfs2_dir_hash_inval(struct gfs2_inode *ip)
>  {
>  	__be64 *hc = ip->i_hash_cache;
>  	ip->i_hash_cache = NULL;
> -	kfree(hc);
> +	if (is_vmalloc_addr(hc))
> +		vfree(hc);
> +	else
> +		kfree(hc);
>  }
>  
>  static inline int gfs2_dirent_sentinel(const struct gfs2_dirent *dent)
> @@ -1114,6 +1126,9 @@ static int dir_double_exhash(struct gfs2_inode *dip)
>  		return PTR_ERR(hc);
>  
>  	h = hc2 = kmalloc(hsize_bytes * 2, GFP_NOFS);
> +	if (hc2 == NULL)
> +		hc2 = vmalloc(hsize_bytes * 2);
> +
>  	if (!hc2)
>  		return -ENOMEM;
>  
> @@ -1145,7 +1160,10 @@ fail:
>  	gfs2_dinode_out(dip, dibh->b_data);
>  	brelse(dibh);
>  out_kfree:
> -	kfree(hc2);
> +	if (is_vmalloc_addr(hc2))
> +		vfree(hc2);
> +	else
> +		kfree(hc2);
>  	return error;
>  }
>  
> @@ -1846,6 +1864,8 @@ static int leaf_dealloc(struct gfs2_inode *dip, u32 index, u32 len,
>  	memset(&rlist, 0, sizeof(struct gfs2_rgrp_list));
>  
>  	ht = kzalloc(size, GFP_NOFS);
> +	if (ht == NULL)
> +		ht = vzalloc(size);
>  	if (!ht)
>  		return -ENOMEM;
>  
> @@ -1933,7 +1953,10 @@ out_rlist:
>  	gfs2_rlist_free(&rlist);
>  	gfs2_quota_unhold(dip);
>  out:
> -	kfree(ht);
> +	if (is_vmalloc_addr(ht))
> +		vfree(ht);
> +	else
> +		kfree(ht);
>  	return error;
>  }
>  
>