2012/7/18 Jeff Layton <jlayton@xxxxxxxxxx>:
> Add code that allows smb_send_rqst to send an array of pages after the
> initial kvec array has been sent. For now, we simply kmap the page
> array and send it using the standard smb_send_kvec function. Eventually,
> we may want to convert this code to use kernel_sendpage under the hood
> and avoid the kmap altogether for the page data.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/cifs/transport.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 54 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index af56e91..006c3fb 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -28,6 +28,7 @@
> #include <linux/delay.h>
> #include <linux/freezer.h>
> #include <linux/tcp.h>
> +#include <linux/highmem.h>
> #include <asm/uaccess.h>
> #include <asm/processor.h>
> #include <linux/mempool.h>
> @@ -241,6 +242,38 @@ smb_send_kvec(struct TCP_Server_Info *server, struct kvec *iov, size_t n_vec,
> return rc;
> }
>
> +/**
> + * rqst_page_to_kvec - Turn a slot in the smb_rqst page array into a kvec
> + * @rqst: pointer to smb_rqst
> + * @idx: index into the array of the page
> + * @iov: pointer to struct kvec that will hold the result
> + *
> + * Helper function to convert a slot in the rqst->rq_pages array into a kvec.
> + * The page will be kmapped and the address placed into iov_base. The length
> + * will then be adjusted according to the ptailoff.
> + */
> +static void
> +cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx,
> + struct kvec *iov)
> +{
> + /*
> + * FIXME: We could avoid this kmap altogether if we used
> + * kernel_sendpage instead of kernel_sendmsg. That will only
> + * work if signing is disabled though as sendpage inlines the
> + * page directly into the fraglist. If userspace modifies the
> + * page after we calculate the signature, then the server will
> + * reject it and may break the connection. kernel_sendmsg does
> + * an extra copy of the data and avoids that issue.
> + */
> + iov->iov_base = kmap(rqst->rq_pages[idx]);
> +
> + /* if last page, don't send beyond this offset into page */
> + if (idx == (rqst->rq_npages - 1))
> + iov->iov_len = rqst->rq_tailsz;
> + else
> + iov->iov_len = rqst->rq_pagesz;
> +}
> +
> static int
> smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
> {
> @@ -248,7 +281,8 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
> struct kvec *iov = rqst->rq_iov;
> int n_vec = rqst->rq_nvec;
> unsigned int smb_buf_length = get_rfc1002_length(iov[0].iov_base);
> - size_t total_len;
> + unsigned int i;
> + size_t total_len = 0, sent;
> struct socket *ssocket = server->ssocket;
> int val = 1;
>
> @@ -259,8 +293,26 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
> kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
> (char *)&val, sizeof(val));
>
> - rc = smb_send_kvec(server, iov, n_vec, &total_len);
> + rc = smb_send_kvec(server, iov, n_vec, &sent);
> + if (rc < 0)
> + goto uncork;
> +
> + total_len += sent;
> +
> + /* now walk the page array and send each page in it */
> + for (i = 0; i < rqst->rq_npages; i++) {
> + struct kvec p_iov;
> +
> + cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> + rc = smb_send_kvec(server, &p_iov, 1, &sent);
> + kunmap(rqst->rq_pages[i]);
> + if (rc < 0)
> + break;
> +
> + total_len += sent;
> + }
>
> +uncork:
> /* uncork it */
> val = 0;
> kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
> --
> 1.7.10.4
>
> --
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Reviewed-by: Pavel Shilovsky <pshilovsky@xxxxxxxxx>
--
Best regards,
Pavel Shilovsky.
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