pdu_fill_pages doesn't calculate correctly pdata_len. first_page_bytes
should be min(PAGE_SIZE-pdu->pdata_off, size)
Thanks,
Lucho
On Tue, Aug 17, 2010 at 11:27 AM, Venkateswararao Jujjuri (JV)
<jvrao@xxxxxxxxxxxxxxxxxx> wrote:
> This patch avoids copy_from_user by employing get_user_pages_fast() on the
> udata buffer. This will eliminate an additonal copy of user buffer into
> kernel buffer befre placing on the virtio ring.
>
> Signed-off-by: Venkateswararao Jujjuri <jvrao@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Badari Pulavarty <pbadari@xxxxxxxxxx>
> ---
> net/9p/client.c | 32 ++++++++++++++++++++-
> net/9p/protocol.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++------
> 2 files changed, 105 insertions(+), 10 deletions(-)
>
> diff --git a/net/9p/client.c b/net/9p/client.c
> index 5487896..7ce58fb 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -36,6 +36,7 @@
> #include <linux/parser.h>
> #include <net/9p/client.h>
> #include <net/9p/transport.h>
> +#include <linux/mm.h>
> #include "protocol.h"
>
> /*
> @@ -521,6 +522,25 @@ static int p9_client_flush(struct p9_client *c, struct p9_req_t *oldreq)
> }
>
> /**
> + * p9_release_req_pages - Release pages after the transaction.
> + * @req - Request buffer.
> + *
> + */
> +static void
> +p9_release_req_pages(struct p9_req_t *req)
> +{
> + int i = 0;
> + while (req->tc->pdata[i] && req->tc->pdata_mapped_pages--) {
> + put_page(req->tc->pdata[i]);
> + req->tc->pdata[i] = NULL;
> + i++;
> + }
> + req->tc->pdata_write_len = 0;
> + req->tc->pdata_read_len = 0;
> +}
> +
> +
> +/**
> * p9_client_rpc - issue a request and wait for a response
> * @c: client session
> * @type: type of request
> @@ -575,6 +595,8 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
> err = c->trans_mod->request(c, req);
> if (err < 0) {
> c->status = Disconnected;
> + if (req->tc->pdata_write_len || req->tc->pdata_read_len)
> + p9_release_req_pages(req);
> goto reterr;
> }
>
> @@ -583,6 +605,8 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
> req->status >= REQ_STATUS_RCVD);
> P9_DPRINTK(P9_DEBUG_MUX, "wait %p tag: %d returned %d\n",
> req->wq, tag, err);
> + if (req->tc->pdata_write_len || req->tc->pdata_read_len)
> + p9_release_req_pages(req);
>
> if (req->status == REQ_STATUS_ERROR) {
> P9_DPRINTK(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
> @@ -1331,9 +1355,15 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
> if (data)
> req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid, offset,
> rsize, data);
> - else
> + else {
> + if (clnt->trans_mod->capability &&
> + clnt->trans_mod->capability(P9_CAP_GET_MAX_SG_PAGES)) {
> +
> + rsize = count;
> + }
> 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 ca63aff..97f313d 100644
> --- a/net/9p/protocol.c
> +++ b/net/9p/protocol.c
> @@ -31,9 +31,12 @@
> #include <linux/slab.h>
> #include <linux/sched.h>
> #include <linux/types.h>
> +#include <linux/parser.h>
> #include <net/9p/9p.h>
> #include <net/9p/client.h>
> #include "protocol.h"
> +#include <net/9p/transport.h>
> +#include <linux/pagemap.h>
>
> #ifndef MIN
> #define MIN(a, b) (((a) < (b)) ? (a) : (b))
> @@ -110,6 +113,51 @@ static size_t pdu_read(struct p9_fcall *pdu, void *data, size_t size)
> return size - len;
> }
>
> +static int
> +pdu_fill_pages(struct p9_fcall *pdu, const char __user *udata, size_t size,
> + int rw, int max_sg_pages)
> +{
> + int nr_pages;
> + uint32_t first_page_bytes = 0;
> + int pdata_len;
> +
> + nr_pages = size >> PAGE_SHIFT;
> + pdu->pdata_off = (size_t)udata & (PAGE_SIZE-1);
> + if (pdu->pdata_off)
> + first_page_bytes = PAGE_SIZE - pdu->pdata_off;
> + if (size - (first_page_bytes + (nr_pages << PAGE_SHIFT))) {
> + /* trailing partial page */
> + nr_pages++;
> + }
> + if (first_page_bytes) {
> + /* leading partial page */
> + nr_pages++;
> + }
> + nr_pages = min(max_sg_pages, nr_pages);
> + pdu->pdata = (struct page **)(pdu->sdata + pdu->size);
> + pdu->pdata_write_len = 0;
> + pdu->pdata_read_len = 0;
> + pdu->pdata_mapped_pages = get_user_pages_fast((unsigned long)udata,
> + nr_pages, rw, pdu->pdata);
> + if (pdu->pdata_mapped_pages < 0) {
> + printk(KERN_WARNING "get_user_pages_fast failed:%d udata:%p"
> + "nr_pages:%d\n", pdu->pdata_mapped_pages,
> + udata, nr_pages);
> + pdu->pdata_mapped_pages = 0;
> + return -1;
> + }
> + if (pdu->pdata_off) {
> + pdata_len = first_page_bytes;
> + pdata_len += min((size - pdata_len),
> + ((size_t)pdu->pdata_mapped_pages - 1) <<
> + PAGE_SHIFT);
> + } else {
> + pdata_len = min(size, (size_t)pdu->pdata_mapped_pages <<
> + PAGE_SHIFT);
> + }
> + return pdata_len;
> +}
> +
> static size_t pdu_write(struct p9_fcall *pdu, const void *data, size_t size)
> {
> size_t len = MIN(pdu->capacity - pdu->size, size);
> @@ -119,15 +167,31 @@ static size_t pdu_write(struct p9_fcall *pdu, const void *data, size_t size)
> }
>
> static size_t
> -pdu_write_u(struct p9_fcall *pdu, const char __user *udata, size_t size)
> +pdu_write_u(struct p9_fcall *pdu, struct p9_client *c, const char __user *udata,
> + size_t size)
> {
> - size_t len = MIN(pdu->capacity - pdu->size, size);
> - int err = copy_from_user(&pdu->sdata[pdu->size], udata, len);
> - if (err)
> - printk(KERN_WARNING "pdu_write_u returning: %d\n", err);
> + size_t len;
> + int err;
> + int max_req_sg_pages = 0;
>
> - pdu->size += len;
> - return size - len;
> + if (c->trans_mod->capability &&
> + (udata && !segment_eq(get_fs(), KERNEL_DS))) {
> + max_req_sg_pages =
> + c->trans_mod->capability(P9_CAP_GET_MAX_SG_PAGES);
> + }
> + if (max_req_sg_pages) {
> + len = pdu_fill_pages(pdu, udata, size, 0, max_req_sg_pages);
> + if (len < 0)
> + return len;
> + pdu->pdata_write_len = len;
> + } else {
> + len = MIN(pdu->capacity - pdu->size, size);
> + err = copy_from_user(&pdu->sdata[pdu->size], udata, len);
> + if (err)
> + printk(KERN_WARNING "pdu_write_u returning: %d\n", err);
> + pdu->size += len;
> + }
> + return len;
> }
>
> /*
> @@ -467,7 +531,8 @@ p9pdu_vwritef(struct p9_fcall *pdu, struct p9_client *c, const char *fmt,
> const char __user *udata =
> va_arg(ap, const void __user *);
> errcode = p9pdu_writef(pdu, c, "d", count);
> - if (!errcode && pdu_write_u(pdu, udata, count))
> + if (!errcode &&
> + pdu_write_u(pdu, c, udata, count) < 0)
> errcode = -EFAULT;
> }
> break;
> --
> 1.6.5.2
>
>
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