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svcrdma: Refactor the RDMA Write path 

Refactor for subsequent changes.

Constify the xdr_buf argument to ensure the code here does not
modify it, and to enable callers to pass in a
"const struct xdr_buf *".

At the same time, rename the helper functions, which emit RDMA
Writes, not RDMA Sends, and add documenting comments.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2020-03-13 10:42:10 -04:00
parent 51bad8cc13
commit ab1394ee7a
1 changed files with 35 additions and 21 deletions
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56
net/sunrpc/xprtrdma/svc_rdma_rw.c
View File

@ -495,27 +495,42 @@ svc_rdma_build_writes(struct svc_rdma_write_info *info,
return -E2BIG;
}
/* Send one of an xdr_buf's kvecs by itself. To send a Reply
* chunk, the whole RPC Reply is written back to the client.
* This function writes either the head or tail of the xdr_buf
* containing the Reply.
/**
* svc_rdma_iov_write - Construct RDMA Writes from an iov
* @info: pointer to write arguments
* @iov: kvec to write
*
* Returns:
* On succes, returns zero
* %-E2BIG if the client-provided Write chunk is too small
* %-ENOMEM if a resource has been exhausted
* %-EIO if an rdma-rw error occurred
*/
static int svc_rdma_send_xdr_kvec(struct svc_rdma_write_info *info,
struct kvec *vec)
static int svc_rdma_iov_write(struct svc_rdma_write_info *info,
const struct kvec *iov)
{
info->wi_base = vec->iov_base;
info->wi_base = iov->iov_base;
return svc_rdma_build_writes(info, svc_rdma_vec_to_sg,
vec->iov_len);
iov->iov_len);
}
/* Send an xdr_buf's page list by itself. A Write chunk is just
* the page list. A Reply chunk is @xdr's head, page list, and
* tail. This function is shared between the two types of chunk.
/**
* svc_rdma_pages_write - Construct RDMA Writes from pages
* @info: pointer to write arguments
* @xdr: xdr_buf with pages to write
* @offset: offset into the content of @xdr
* @length: number of bytes to write
*
* Returns:
* On succes, returns zero
* %-E2BIG if the client-provided Write chunk is too small
* %-ENOMEM if a resource has been exhausted
* %-EIO if an rdma-rw error occurred
*/
static int svc_rdma_send_xdr_pagelist(struct svc_rdma_write_info *info,
struct xdr_buf *xdr,
unsigned int offset,
unsigned long length)
static int svc_rdma_pages_write(struct svc_rdma_write_info *info,
const struct xdr_buf *xdr,
unsigned int offset,
unsigned long length)
{
info->wi_xdr = xdr;
info->wi_next_off = offset - xdr->head[0].iov_len;
@ -552,7 +567,7 @@ int svc_rdma_send_write_chunk(struct svcxprt_rdma *rdma, __be32 *wr_ch,
if (!info)
return -ENOMEM;
ret = svc_rdma_send_xdr_pagelist(info, xdr, offset, length);
ret = svc_rdma_pages_write(info, xdr, offset, length);
if (ret < 0)
goto out_err;
@ -592,7 +607,7 @@ int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma,
if (!info)
return -ENOMEM;
ret = svc_rdma_send_xdr_kvec(info, &xdr->head[0]);
ret = svc_rdma_iov_write(info, &xdr->head[0]);
if (ret < 0)
goto out_err;
consumed = xdr->head[0].iov_len;
@ -601,16 +616,15 @@ int svc_rdma_send_reply_chunk(struct svcxprt_rdma *rdma,
* client did not provide Write chunks.
*/
if (!rctxt->rc_write_list && xdr->page_len) {
ret = svc_rdma_send_xdr_pagelist(info, xdr,
xdr->head[0].iov_len,
xdr->page_len);
ret = svc_rdma_pages_write(info, xdr, xdr->head[0].iov_len,
xdr->page_len);
if (ret < 0)
goto out_err;
consumed += xdr->page_len;
}
if (xdr->tail[0].iov_len) {
ret = svc_rdma_send_xdr_kvec(info, &xdr->tail[0]);
ret = svc_rdma_iov_write(info, &xdr->tail[0]);
if (ret < 0)
goto out_err;
consumed += xdr->tail[0].iov_len;