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SUNRPC dont update timeout value on connection reset

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Current behaviour: every time a v3 operation is re-sent to the server
we update (double) the timeout. There is no distinction between whether
or not the previous timer had expired before the re-sent happened.

Here's the scenario:
1. Client sends a v3 operation
2. Server RST-s the connection (prior to the timeout) (eg., connection
is immediately reset)
3. Client re-sends a v3 operation but the timeout is now 120sec.

As a result, an application sees 2mins pause before a retry in case
server again does not reply.

Instead, this patch proposes to keep track off when the minor timeout
should happen and if it didn't, then don't update the new timeout.
Value is updated based on the previous value to make timeouts
predictable.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Olga Kornievskaia 2020-07-15 13:17:52 -04:00 committed by Trond Myklebust
parent ce368536dd
commit 7de62bc09f
2 changed files with 10 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/linux/sunrpc/xprt.h
View file

@ -101,6 +101,7 @@ struct rpc_rqst {
* used in the softirq.
*/
unsigned long rq_majortimeo; /* major timeout alarm */
unsigned long rq_minortimeo; /* minor timeout alarm */
unsigned long rq_timeout; /* Current timeout value */
ktime_t rq_rtt; /* round-trip time */
unsigned int rq_retries; /* # of retries */

9
net/sunrpc/xprt.c
View file

@ -607,6 +607,11 @@ static void xprt_reset_majortimeo(struct rpc_rqst *req)
req->rq_majortimeo += xprt_calc_majortimeo(req);
}
static void xprt_reset_minortimeo(struct rpc_rqst *req)
{
req->rq_minortimeo += req->rq_timeout;
}
static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
{
unsigned long time_init;
@ -618,6 +623,7 @@ static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
req->rq_timeout = task->tk_client->cl_timeout->to_initval;
req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
req->rq_minortimeo = time_init + req->rq_timeout;
}
/**
@ -631,6 +637,8 @@ int xprt_adjust_timeout(struct rpc_rqst *req)
const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
int status = 0;
if (time_before(jiffies, req->rq_minortimeo))
return status;
if (time_before(jiffies, req->rq_majortimeo)) {
if (to->to_exponential)
req->rq_timeout <<= 1;
@ -649,6 +657,7 @@ int xprt_adjust_timeout(struct rpc_rqst *req)
spin_unlock(&xprt->transport_lock);
status = -ETIMEDOUT;
}
xprt_reset_minortimeo(req);
if (req->rq_timeout == 0) {
printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");