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SubjectRe: [Patch v2 12/15] CIFS: Pass page offset for encrypting
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On 5/30/2018 3:48 PM, Long Li wrote:
> From: Long Li <longli@microsoft.com>
>
> Encryption function needs to read data starting page offset from input
> buffer.
>
> This doesn't affect decryption path since it allocates its own page
> buffers.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
> fs/cifs/smb2ops.c | 20 +++++++++++++-------
> 1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
> index 1fa1c29..38d19b6 100644
> --- a/fs/cifs/smb2ops.c
> +++ b/fs/cifs/smb2ops.c
> @@ -2189,9 +2189,10 @@ init_sg(struct smb_rqst *rqst, u8 *sign)
> smb2_sg_set_buf(&sg[i], rqst->rq_iov[i].iov_base,
> rqst->rq_iov[i].iov_len);
> for (j = 0; i < sg_len - 1; i++, j++) {
> - unsigned int len = (j < rqst->rq_npages - 1) ? rqst->rq_pagesz
> - : rqst->rq_tailsz;
> - sg_set_page(&sg[i], rqst->rq_pages[j], len, 0);
> + unsigned int len, offset;
> +
> + rqst_page_get_length(rqst, j, &len, &offset);
> + sg_set_page(&sg[i], rqst->rq_pages[j], len, offset);
> }
> smb2_sg_set_buf(&sg[sg_len - 1], sign, SMB2_SIGNATURE_SIZE);
> return sg;
> @@ -2332,6 +2333,7 @@ smb3_init_transform_rq(struct TCP_Server_Info *server, struct smb_rqst *new_rq,
> return rc;
>
> new_rq->rq_pages = pages;
> + new_rq->rq_offset = old_rq->rq_offset;
> new_rq->rq_npages = old_rq->rq_npages;
> new_rq->rq_pagesz = old_rq->rq_pagesz;
> new_rq->rq_tailsz = old_rq->rq_tailsz;
> @@ -2363,10 +2365,14 @@ smb3_init_transform_rq(struct TCP_Server_Info *server, struct smb_rqst *new_rq,
>
> /* copy pages form the old */
> for (i = 0; i < npages; i++) {
> - char *dst = kmap(new_rq->rq_pages[i]);
> - char *src = kmap(old_rq->rq_pages[i]);
> - unsigned int len = (i < npages - 1) ? new_rq->rq_pagesz :
> - new_rq->rq_tailsz;
> + char *dst, *src;
> + unsigned int offset, len;
> +
> + rqst_page_get_length(new_rq, i, &len, &offset);
> +
> + dst = (char *) kmap(new_rq->rq_pages[i]) + offset;
> + src = (char *) kmap(old_rq->rq_pages[i]) + offset;

Ouch! TWO kmap/kunmaps per page of data? Is there not already a kva,
at least for the destination (message)?

Tom.


> +
> memcpy(dst, src, len);
> kunmap(new_rq->rq_pages[i]);
> kunmap(old_rq->rq_pages[i]);
>

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