[PATCH 7/7] [net/9p] Handle TREAD/RERROR case in !dotl case.

["Venkateswararao Jujjuri (JV)" <jvrao@linux.vnet.ibm.com>]

On 2/6/2011 11:21 PM, Venkateswararao Jujjuri (JV) wrote:
> In addition, this patch also avoids zero copy for short reads in !dotl case.
> 
> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
> 
> Conflicts:
> 
> 	net/9p/protocol.c
> ---
>  include/net/9p/9p.h |    2 +
>  net/9p/client.c     |   74 +++++++++++++++++++++++++++++++++-----------------
>  2 files changed, 51 insertions(+), 25 deletions(-)
> 
> diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
> index 9c939c2..7313801 100644
> --- a/include/net/9p/9p.h
> +++ b/include/net/9p/9p.h
> @@ -320,6 +320,8 @@ enum p9_qid_t {
>  /* Room for readdir header */
>  #define P9_READDIRHDRSZ	24
> 
> +#define P9_ERRMAX 256 /* FIXME: Check what is the correct value */
> +
>  /**
>   * struct p9_str - length prefixed string type
>   * @len: length of the string
> diff --git a/net/9p/client.c b/net/9p/client.c
> index f939edf..7f34c42 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -443,6 +443,7 @@ static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
>  {
>  	int8_t type;
>  	int err;
> +	int ecode;
> 
>  	err = p9_parse_header(req->rc, NULL, &type, NULL, 0);
>  	if (err) {
> @@ -450,36 +451,53 @@ static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
>  		return err;
>  	}
> 
> -	if (type == P9_RERROR || type == P9_RLERROR) {
> -		int ecode;
> -
> -		if (!p9_is_proto_dotl(c)) {
> -			char *ename;
> +	if (type != P9_RERROR && type != P9_RLERROR) 
> +		return 0;
> 
> -			err = p9pdu_readf(req->rc, c->proto_version, "s?d",
> -								&ename, &ecode);
> -			if (err)
> -				goto out_err;
> +	if (!p9_is_proto_dotl(c)) {
> +		char *ename;
> +
> +		if (req->tc->pbuf_size) {
> +			/* Handle user buffers */
> +			size_t len = req->rc->size - req->rc->offset;
> +			if (req->tc->pbuf &&
> +					!segment_eq(get_fs(), KERNEL_DS)) {
> +				/* User Buffer */
> +				err = copy_from_user(
> +					&req->rc->sdata[req->rc->offset],
> +					req->tc->pbuf, len);
> +				if (err) {
> +					err = -EFAULT;
> +					return err;
> +				}
> +			} else {
> +				/* Kernel Buffer */
> +				memmove(&req->rc->sdata[req->rc->offset],
> +						req->tc->pbuf, len);
> +			}
> +		}
> +		err = p9pdu_readf(req->rc, c->proto_version, "s?d",
> +				&ename, &ecode);
> +		if (err)
> +			goto out_err;
> 
> -			if (p9_is_proto_dotu(c))
> -				err = -ecode;
> +		if (p9_is_proto_dotu(c))
> +			err = -ecode;
> 
> -			if (!err || !IS_ERR_VALUE(err)) {
> -				err = p9_errstr2errno(ename, strlen(ename));
> +		if (!err || !IS_ERR_VALUE(err)) {
> +			err = p9_errstr2errno(ename, strlen(ename));
> 
> -				P9_DPRINTK(P9_DEBUG_9P, "<<< RERROR (%d) %s\n", -ecode, ename);
> +			P9_DPRINTK(P9_DEBUG_9P, "<<< RERROR (%d) %s\n", -ecode, ename);
> 
> -				kfree(ename);
> -			}
> -		} else {
> -			err = p9pdu_readf(req->rc, c->proto_version, "d", &ecode);
> -			err = -ecode;
> -
> -			P9_DPRINTK(P9_DEBUG_9P, "<<< RLERROR (%d)\n", -ecode);
> +			kfree(ename);
>  		}
> +	} else {
> +		err = p9pdu_readf(req->rc, c->proto_version, "d", &ecode);
> +		err = -ecode;
> +
> +		P9_DPRINTK(P9_DEBUG_9P, "<<< RLERROR (%d)\n", -ecode);
> +	}
> 
> -	} else
> -		err = 0;
> 
>  	return err;
> 
> @@ -1270,8 +1288,14 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
>  	if (count < rsize)
>  		rsize = count;
> 
> -	if ((clnt->trans_mod->pref & P9_TRANS_PREF_PAYLOAD_MASK) ==
> -			P9_TRANS_PREF_PAYLOAD_SEP) {
> +	/* for !p9_proto_2000L, we need to have enough space on PDU
> +	 * to handle TREAD/RERROR. Hence don't attempt payload
> +	 * seperaion for small reads even if the transport prefers
> +	 * P9_TRANS_PREF_PAYLOAD_SEP */
> +	if (((clnt->trans_mod->pref & P9_TRANS_PREF_PAYLOAD_MASK) ==
> +			P9_TRANS_PREF_PAYLOAD_SEP) &&
> +			((clnt->proto_version == p9_proto_2000L) ||
> +			 rsize > 2 * P9_ERRMAX) ) {
>  		req = p9_client_rpc(clnt, P9_TREAD, "dqE", fid->fid, offset,
>  				rsize, data ? data : udata);
>  	} else {