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| author |   Chuck Lever <chuck.lever@oracle.com> | 2018-07-27 11:18:54 -0400 |
|---|---|---|
| committer |   J. Bruce Fields <bfields@redhat.com> | 2018-08-09 16:11:21 -0400 |
| commit | a53d5cb0646a12586ae45c892c7a411d47ee1a1d (patch) | |
| tree | 8342ebe172d876e8e0358fc0531cf3f75d3e7e58 /net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | |
| parent | nfsd: Mark expected switch fall-through (diff) | |
| download | linux-dev-a53d5cb0646a12586ae45c892c7a411d47ee1a1d.tar.xz linux-dev-a53d5cb0646a12586ae45c892c7a411d47ee1a1d.zip | |
svcrdma: Avoid releasing a page in svc_xprt_release()
svc_xprt_release() invokes svc_free_res_pages(), which releases
pages between rq_respages and rq_next_page.
Historically, the RPC/RDMA transport has set these two pointers to
be different by one, which means:
- one page gets released when svc_recv returns 0. This normally
happens whenever one or more RDMA Reads need to be dispatched to
complete construction of an RPC Call.
- one page gets released after every call to svc_send.
In both cases, this released page is immediately refilled by
svc_alloc_arg. There does not seem to be a reason for releasing this
page.
To avoid this unnecessary memory allocator traffic, set rq_next_page
more carefully.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/sunrpc/xprtrdma/svc_rdma_recvfrom.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index 841fca143804..ddb7def48b12 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -366,9 +366,6 @@ static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp, arg->page_base = 0; arg->buflen = ctxt->rc_byte_len; arg->len = ctxt->rc_byte_len; - - rqstp->rq_respages = &rqstp->rq_pages[0]; - rqstp->rq_next_page = rqstp->rq_respages + 1; } /* This accommodates the largest possible Write chunk, @@ -730,6 +727,12 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) svc_rdma_build_arg_xdr(rqstp, ctxt); + /* Prevent svc_xprt_release from releasing pages in rq_pages + * if we return 0 or an error. + */ + rqstp->rq_respages = rqstp->rq_pages; + rqstp->rq_next_page = rqstp->rq_respages; + p = (__be32 *)rqstp->rq_arg.head[0].iov_base; ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg); if (ret < 0) |