xprtrdma: Revert 3d4cf35bd4fa ("xprtrdma: Reply buffer exhaustion...")
authorChuck Lever <chuck.lever@oracle.com>
Tue, 6 Sep 2016 15:22:49 +0000 (11:22 -0400)
committerTrond Myklebust <trond.myklebust@primarydata.com>
Tue, 6 Sep 2016 19:59:35 +0000 (15:59 -0400)
commit78d506e1b7071b24850fd5ac22b896c459b0a04c
tree141a19e4872ffcd39c6f181680820d0b6ac418b6
parent334a8f37115bf35e38617315a360a91ac4f2b2c6
xprtrdma: Revert 3d4cf35bd4fa ("xprtrdma: Reply buffer exhaustion...")

Receive buffer exhaustion, if it were to actually occur, would be
catastrophic. However, when there are no reply buffers to post, that
means all of them have already been posted and are waiting for
incoming replies. By design, there can never be more RPCs in flight
than there are available receive buffers.

A receive buffer can be left posted after an RPC exits without a
received reply; say, due to a credential problem or a soft timeout.
This does not result in fewer posted receive buffers than there are
pending RPCs, and there is already logic in xprtrdma to deal
appropriately with this case.

It also looks like the "+ 2" that was removed was accidentally
accommodating the number of extra receive buffers needed for
receiving backchannel requests. That will need to be addressed by
another patch.

Fixes: 3d4cf35bd4fa ("xprtrdma: Reply buffer exhaustion can be...")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
net/sunrpc/xprtrdma/verbs.c