On 2/11/2011 11:35 AM, Aneesh Kumar K. V wrote:
> On Thu, 10 Feb 2011 17:25:10 -0800, "Venkateswararao Jujjuri (JV)" <jvrao@xxxxxxxxxxxxxxxxxx> wrote:
>> Signed-off-by: Venkateswararao Jujjuri <jvrao@xxxxxxxxxxxxxxxxxx>
>> ---
>> net/9p/client.c | 47 +++++++++++++++++++++++++++++++++--------------
>> net/9p/protocol.c | 21 +++++++++++++++++++++
>> 2 files changed, 54 insertions(+), 14 deletions(-)
>>
>> diff --git a/net/9p/client.c b/net/9p/client.c
>> index a848bca..f6d8531 100644
>> --- a/net/9p/client.c
>> +++ b/net/9p/client.c
>> @@ -1270,7 +1270,15 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
>> if (count < rsize)
>> rsize = count;
>>
>> - req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset, rsize);
>> + /* Don't bother zerocopy form small IO (< 1024) */
>> + if (((clnt->trans_mod->pref & P9_TRANS_PREF_PAYLOAD_MASK) ==
>> + P9_TRANS_PREF_PAYLOAD_SEP) && (rsize > 1024)) {
>> + req = p9_client_rpc(clnt, P9_TREAD, "dqE", fid->fid, offset,
>> + rsize, data, udata);
>> + } else {
>> + req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
>> + rsize);
>> + }
>> if (IS_ERR(req)) {
>> err = PTR_ERR(req);
>> goto error;
>> @@ -1284,13 +1292,15 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
>>
>> P9_DPRINTK(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
>>
>> - if (data) {
>> - memmove(data, dataptr, count);
>> - } else {
>> - err = copy_to_user(udata, dataptr, count);
>> - if (err) {
>> - err = -EFAULT;
>> - goto free_and_error;
>> + if (!req->tc->pbuf_size) {
>> + if (data) {
>> + memmove(data, dataptr, count);
>> + } else {
>> + err = copy_to_user(udata, dataptr, count);
>> + if (err) {
>> + err = -EFAULT;
>> + goto free_and_error;
>> + }
>> }
>> }
>> p9_free_req(clnt, req);
>> @@ -1323,12 +1333,21 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
>>
>> if (count < rsize)
>> rsize = count;
>> - if (data)
>> - req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid, offset,
>> - rsize, data);
>> - else
>> - req = p9_client_rpc(clnt, P9_TWRITE, "dqU", fid->fid, offset,
>> - rsize, udata);
>> +
>> + /* Don't bother zerocopy form small IO (< 1024) */
>> + if (((clnt->trans_mod->pref & P9_TRANS_PREF_PAYLOAD_MASK) ==
>> + P9_TRANS_PREF_PAYLOAD_SEP) && (rsize > 1024)) {
>> + req = p9_client_rpc(clnt, P9_TWRITE, "dqE", fid->fid, offset,
>> + rsize, data, udata);
>> + } else {
>> + if (data)
>> + req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid,
>> + offset, rsize, data);
>> + else
>> + req = p9_client_rpc(clnt, P9_TWRITE, "dqU", fid->fid,
>> + offset, rsize, udata);
>> + }
>> +
>> if (IS_ERR(req)) {
>> err = PTR_ERR(req);
>> goto error;
>> diff --git a/net/9p/protocol.c b/net/9p/protocol.c
>> index 5936c50..830b999 100644
>> --- a/net/9p/protocol.c
>> +++ b/net/9p/protocol.c
>> @@ -114,6 +114,17 @@ pdu_write_u(struct p9_fcall *pdu, const char __user *udata, size_t size)
>> return size - len;
>> }
>>
>> +static size_t
>> +pdu_write_urw(struct p9_fcall *pdu, const char *kdata, const char __user *udata,
>> + size_t size)
>> +{
>> + size_t len = min(pdu->capacity - pdu->size, size);
>
> Why do we need to do this ? We are not placing anything in the pdu right ?
But still as per protocol each packet should be <= msize.
I will have another patch series introducing another size bufsize in addition to
msize.
Where bufsize will represent small PDUs (which is <= msize).
>
>> + pdu->pubuf = (char __user *)udata;
>> + pdu->pkbuf = (char *)kdata;
>> + pdu->pbuf_size = len;
>> + return size - len;
>
> Does this mean a zero copy write of a buffer larger than msize will
> result in a failure ?
No; No failures.
If your recall, all our read/write routines doesn't guarantee writing entire
request in one shot..At multiple levels we adjust the read/write size
and the top level takes care of it by dividing the buffer into multiple
reads/writes.
This is not anything new in zero copy .. same thing happens even in the current
code. (pdu_write_u)
- JV
>
>> +}
>> +
>> /*
>> b - int8_t
>> w - int16_t
>> @@ -445,6 +456,16 @@ p9pdu_vwritef(struct p9_fcall *pdu, int proto_version, const char *fmt,
>> errcode = -EFAULT;
>> }
>> break;
>> + case 'E':{
>> + int32_t cnt = va_arg(ap, int32_t);
>> + const char *k = va_arg(ap, const void *);
>> + const char *u = va_arg(ap, const void *);
>> + errcode = p9pdu_writef(pdu, proto_version, "d",
>> + cnt);
>> + if (!errcode && pdu_write_urw(pdu, k, u, cnt))
>> + errcode = -EFAULT;
>> + }
>> + break;
>> case 'U':{
>> int32_t count = va_arg(ap, int32_t);
>> const char __user *udata =
>
>
> -aneesh
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