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svcrdma: Add zero padding if the client doesn't send it

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See RFC 5666 section 3.7: clients don't have to send zero XDR
padding.

BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=246
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Chuck Lever 2014-07-22 16:00:40 -04:00 • committed by J. Bruce Fields
commit e560e3b510
1 changed files with 28 additions and 0 deletions
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28
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
View file

@ -43,6 +43,7 @@
#include <linux/sunrpc/debug.h>
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/spinlock.h>
#include <linux/highmem.h>
#include <asm/unaligned.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
@ -435,6 +436,32 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
return ret;
}
/*
* To avoid a separate RDMA READ just for a handful of zero bytes,
* RFC 5666 section 3.7 allows the client to omit the XDR zero pad
* in chunk lists.
*/
static void
rdma_fix_xdr_pad(struct xdr_buf *buf)
{
unsigned int page_len = buf->page_len;
unsigned int size = (XDR_QUADLEN(page_len) << 2) - page_len;
unsigned int offset, pg_no;
char *p;
if (size == 0)
return;
pg_no = page_len >> PAGE_SHIFT;
offset = page_len & ~PAGE_MASK;
p = page_address(buf->pages[pg_no]);
memset(p + offset, 0, size);
buf->page_len += size;
buf->buflen += size;
buf->len += size;
}
static int rdma_read_complete(struct svc_rqst *rqstp,
struct svc_rdma_op_ctxt *head)
{
@ -449,6 +476,7 @@ static int rdma_read_complete(struct svc_rqst *rqstp,
rqstp->rq_pages[page_no] = head->pages[page_no];
}
/* Point rq_arg.pages past header */
rdma_fix_xdr_pad(&head->arg);
rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];
rqstp->rq_arg.page_len = head->arg.page_len;
rqstp->rq_arg.page_base = head->arg.page_base;