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SubjectRe: [Patch v2 08/15] CIFS: SMBD: Support page offset in RDMA send
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On 5/30/2018 3:48 PM, Long Li wrote:
> From: Long Li <longli@microsoft.com>
>
> The RDMA send function needs to look at offset in the request pages, and
> send data starting from there.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
> fs/cifs/smbdirect.c | 27 +++++++++++++++++++--------
> 1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
> index c62f7c9..6141e3c 100644
> --- a/fs/cifs/smbdirect.c
> +++ b/fs/cifs/smbdirect.c
> @@ -17,6 +17,7 @@
> #include <linux/highmem.h>
> #include "smbdirect.h"
> #include "cifs_debug.h"
> +#include "cifsproto.h"
>
> static struct smbd_response *get_empty_queue_buffer(
> struct smbd_connection *info);
> @@ -2082,7 +2083,7 @@ int smbd_send(struct smbd_connection *info, struct smb_rqst *rqst)
> struct kvec vec;
> int nvecs;
> int size;
> - int buflen = 0, remaining_data_length;
> + unsigned int buflen = 0, remaining_data_length;
> int start, i, j;
> int max_iov_size =
> info->max_send_size - sizeof(struct smbd_data_transfer);
> @@ -2113,10 +2114,17 @@ int smbd_send(struct smbd_connection *info, struct smb_rqst *rqst)
> buflen += iov[i].iov_len;
> }
>
> - /* add in the page array if there is one */
> + /*
> + * Add in the page array if there is one. The caller needs to set
> + * rq_tailsz to PAGE_SIZE when the buffer has multiple pages and
> + * ends at page boundary
> + */
> if (rqst->rq_npages) {
> - buflen += rqst->rq_pagesz * (rqst->rq_npages - 1);
> - buflen += rqst->rq_tailsz;
> + if (rqst->rq_npages == 1)
> + buflen += rqst->rq_tailsz;
> + else
> + buflen += rqst->rq_pagesz * (rqst->rq_npages - 1) -
> + rqst->rq_offset + rqst->rq_tailsz;
> }

This code is really confusing and redundant. It tests npages > 0,
then tests npages == 1, then does an else. Why not call the helper
like the following smbd_send()?

Tom.

>
> if (buflen + sizeof(struct smbd_data_transfer) >
> @@ -2213,8 +2221,9 @@ int smbd_send(struct smbd_connection *info, struct smb_rqst *rqst)
>
> /* now sending pages if there are any */
> for (i = 0; i < rqst->rq_npages; i++) {
> - buflen = (i == rqst->rq_npages-1) ?
> - rqst->rq_tailsz : rqst->rq_pagesz;
> + unsigned int offset;
> +
> + rqst_page_get_length(rqst, i, &buflen, &offset);
> nvecs = (buflen + max_iov_size - 1) / max_iov_size;
> log_write(INFO, "sending pages buflen=%d nvecs=%d\n",
> buflen, nvecs);
> @@ -2225,9 +2234,11 @@ int smbd_send(struct smbd_connection *info, struct smb_rqst *rqst)
> remaining_data_length -= size;
> log_write(INFO, "sending pages i=%d offset=%d size=%d"
> " remaining_data_length=%d\n",
> - i, j*max_iov_size, size, remaining_data_length);
> + i, j*max_iov_size+offset, size,
> + remaining_data_length);
> rc = smbd_post_send_page(
> - info, rqst->rq_pages[i], j*max_iov_size,
> + info, rqst->rq_pages[i],
> + j*max_iov_size + offset,
> size, remaining_data_length);
> if (rc)
> goto done;
>

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