Re: [PATCH 2/2] NFS: Cleanup decode_attr_fs_locations function.

[Benny Halevy <bhalevy@panasas.com>]

On Oct. 18, 2008, 0:52 +0200, Dean Hildebrand <seattleplus@gmail.com> wrote:
> a) Use correct data types.
> b) Use nloc and nserv instead of n and m variable names.
> c) Try to clean up formatting of debugging statements.
> d) Move while loops to for loops.
> 
> Signed-off-by: Dean Hildebrand <dhildeb@us.ibm.com>
> ---
>  fs/nfs/nfs4xdr.c |   38 ++++++++++++++++++++------------------
>  1 files changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index 0b4c565..b7de923 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -2560,7 +2560,8 @@ out_eio:
>  
>  static int decode_attr_fs_locations(struct xdr_stream *xdr, uint32_t *bitmap, struct nfs4_fs_locations *res)
>  {
> -	int n;
> +	u32 nloc;
> +	unsigned int i;
>  	__be32 *p;
>  	int status = -EIO;
>  
> @@ -2574,37 +2575,37 @@ static int decode_attr_fs_locations(struct xdr_stream *xdr, uint32_t *bitmap, st
>  	if (unlikely(status != 0))
>  		goto out;
>  	READ_BUF(4);
> -	READ32(n);
> -	if (n <= 0)
> +	READ32(nloc);
> +	if (nloc <= 0)
>  		goto out_eio;
>  
> -	if (n > NFS4_FS_LOCATIONS_MAXENTRIES) {
> -		dprintk("\n%s: Using first %u of %d fs locations\n",
> -			__func__, NFS4_FS_LOCATIONS_MAXENTRIES, n);
> -		n = NFS4_FS_LOCATIONS_MAXENTRIES;
> +	if (nloc > NFS4_FS_LOCATIONS_MAXENTRIES) {
> +		dprintk("\n%s: Using first %u of %u fs locations\n",
> +			__func__, NFS4_FS_LOCATIONS_MAXENTRIES, nloc);
> +		nloc = NFS4_FS_LOCATIONS_MAXENTRIES;
>  	}
>  
>  	res->nlocations = 0;
> -	while (res->nlocations < n) {
> -		u32 m;
> -		unsigned int totalserv, i;
> -		struct nfs4_fs_location *loc = &res->locations[res->nlocations];
> +	for (i = 0; i < nloc; i++) {

you could also keep using res->nlocations as iterator, e.g.

-	res->nlocations = 0;
-	while (res->nlocations < n) {
+	for (res->nlocations = 0; res->nlocations < nloc; res->nlocations++) {

Since it is incremented every time we go through the loop
anyway using the auxiliary variable is useless.
(It could possibly improve performance a bit for long
arrays if the compiler would've used a register for the local
variable, but then you should assign its final value
to res->nlocations, not increment it every iteration.
However, I don't think it's worth it in this case)

> +		u32 nserv;
> +		unsigned int totalserv, j;
> +		struct nfs4_fs_location *loc = &res->locations[i];
>  
>  		READ_BUF(4);
> -		READ32(m);
> +		READ32(nserv);
>  
> -		totalserv = m;
> -		if (m >  NFS4_FS_LOCATION_MAXSERVERS) {
> +		totalserv = nserv;
> +		if (nserv >  NFS4_FS_LOCATION_MAXSERVERS) {
>  			dprintk("\n%s: Using first %u of %u servers "
>  				"returned for location %u\n",
>  				__func__, NFS4_FS_LOCATION_MAXSERVERS,
> -				m, res->nlocations);
> -			m = NFS4_FS_LOCATION_MAXSERVERS;
> +				nserv, i);
> +			nserv = NFS4_FS_LOCATION_MAXSERVERS;
>  		}
>  
>  		loc->nservers = 0;
>  		dprintk("%s: servers ", __func__);
> -		while (loc->nservers < m) {
> +		for (j = 0; j < nserv; j++) {

ditto for loc->nservers.

Benny

>  			struct nfs4_string *server = &loc->servers[loc->nservers];
>  			status = decode_opaque_inline(xdr, &server->len, &server->data);
>  			if (unlikely(status != 0))
> @@ -2612,9 +2613,10 @@ static int decode_attr_fs_locations(struct xdr_stream *xdr, uint32_t *bitmap, st
>  			dprintk("%s ", server->data);
>  			loc->nservers++;
>  		}
> +		dprintk("\n");
>  
>  		/* Decode and ignore overflow servers */
> -		for (i = loc->nservers; i < totalserv; i++) {
> +		for (j = loc->nservers; j < totalserv; j++) {
>  			unsigned int len;
>  			char *data;
>  			status = decode_opaque_inline(xdr, &len, &data);