Re: [PATCH v8 31/32] NFSv4.1: define nfs_generic_pg_test

[Boaz Harrosh <bharrosh@panasas.com>]

On 05/26/2011 12:30 AM, Benny Halevy wrote:
> By default, unless pnfs is used coalesce pages until pg_bsize
> (rsize or wsize) is reached.
> 
> pnfs layout drivers define their own pg_test methods that use
> pnfs_generic_pg_test and need to define their own I/O size
> limits (e.g. based on the file stripe size).
> 
> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
> ---
>  fs/nfs/pagelist.c |   17 +++++++----------
>  1 files changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> index 0209ffb..c795660 100644
> --- a/fs/nfs/pagelist.c
> +++ b/fs/nfs/pagelist.c
> @@ -204,6 +204,11 @@ nfs_wait_on_request(struct nfs_page *req)
>  			TASK_UNINTERRUPTIBLE);
>  }
>  
> +static bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_page *prev, struct nfs_page *req)
> +{
> +	return desc->pg_count + req->wb_bytes <= desc->pg_bsize;
> +}
> +
>  /**
>   * nfs_pageio_init - initialise a page io descriptor
>   * @desc: pointer to descriptor
> @@ -229,7 +234,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
>  	desc->pg_ioflags = io_flags;
>  	desc->pg_error = 0;
>  	desc->pg_lseg = NULL;
> -	desc->pg_test = NULL;
> +	desc->pg_test = nfs_generic_pg_test;
>  }
>  
>  /**
> @@ -259,13 +264,7 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
>  		return false;
>  	if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
>  		return false;
> -	/*
> -	 * Non-whole file layouts need to check that req is inside of
> -	 * pgio->pg_lseg.
> -	 */
> -	if (pgio->pg_test && !pgio->pg_test(pgio, prev, req))
> -		return false;
> -	return true;
> +	return pgio->pg_test(pgio, prev, req);
>  }
>  
>  /**
> @@ -294,8 +293,6 @@ static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
>  		if (desc->pg_bsize < PAGE_SIZE)
>  			return 0;

What about this part? what is desc->pg_bsize? Is it not what was negotiated with the
MDS? this too should be ignored in PNFS. Maybe just add it to the generic test? me think

Boaz

>  		newlen += desc->pg_count;
> -		if (newlen > desc->pg_bsize)
> -			return 0;
>  		prev = nfs_list_entry(desc->pg_list.prev);
>  		if (!nfs_can_coalesce_requests(prev, req, desc))
>  			return 0;