xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

xprtrdma: Add ro_unmap_safe memreg method

Browse Source 
There needs to be a safe method of releasing registered memory
resources when an RPC terminates. Safe can mean a number of things:

+ Doesn't have to sleep

+ Doesn't rely on having a QP in RTS

ro_unmap_safe will be that safe method. It can be used in cases
where synchronous memory invalidation can deadlock, or needs to have
an active QP.

The important case is fencing an RPC's memory regions after it is
signaled (^C) and before it exits. If this is not done, there is a
window where the server can write an RPC reply into memory that the
client has released and re-used for some other purpose.

Note that this is a full solution for FRWR, but FMR and physical
still have some gaps where a particularly bad server can wreak
some havoc on the client. These gaps are not made worse by this
patch and are expected to be exceptionally rare and timing-based.
They are noted in documenting comments.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever
2016-05-02 14:42:46 -04:00
committed by Anna Schumaker
parent 763bc230b6
commit ead3f26e35
6 changed files with 150 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
net/sunrpc/xprtrdma/frwr_ops.c
View File

@@ -614,6 +614,32 @@ reset_mrs:
goto unmap;
}
/* Use a slow, safe mechanism to invalidate all memory regions
* that were registered for "req".
*/
static void
frwr_op_unmap_safe(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
bool sync)
{
struct rpcrdma_mr_seg *seg;
struct rpcrdma_mw *mw;
unsigned int i;
for (i = 0; req->rl_nchunks; req->rl_nchunks--) {
seg = &req->rl_segments[i];
mw = seg->rl_mw;
if (sync)
__frwr_reset_and_unmap(r_xprt, mw);
else
__frwr_queue_recovery(mw);
i += seg->mr_nsegs;
seg->mr_nsegs = 0;
seg->rl_mw = NULL;
}
}
/* Post a LOCAL_INV Work Request to prevent further remote access
* via RDMA READ or RDMA WRITE.
*/
@@ -675,6 +701,7 @@ frwr_op_destroy(struct rpcrdma_buffer *buf)
const struct rpcrdma_memreg_ops rpcrdma_frwr_memreg_ops = {
.ro_map = frwr_op_map,
.ro_unmap_sync = frwr_op_unmap_sync,
.ro_unmap_safe = frwr_op_unmap_safe,
.ro_unmap = frwr_op_unmap,
.ro_open = frwr_op_open,
.ro_maxpages = frwr_op_maxpages,