tree 924d70a458777408f56a2194a87a6bb14f825644
parent 4201c7464753827803366b40e82eb050c04ebdef
author Chuck Lever <chuck.lever@oracle.com> 1525721289 -0400
committer J. Bruce Fields <bfields@redhat.com> 1526068137 -0400

svcrdma: Don't overrun the SGE array in svc_rdma_send_ctxt

Receive buffers are always the same size, but each Send WR has a
variable number of SGEs, based on the contents of the xdr_buf being
sent.

While assembling a Send WR, keep track of the number of SGEs so that
we don't exceed the device's maximum, or walk off the end of the
Send SGE array.

For now the Send path just fails if it exceeds the maximum.

The current logic in svc_rdma_accept bases the maximum number of
Send SGEs on the largest NFS request that can be sent or received.
In the transport layer, the limit is actually based on the
capabilities of the underlying device, not on properties of the
Upper Layer Protocol.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>