Commit 37324e6b authored by Chuck Lever's avatar Chuck Lever
Browse files

SUNRPC: Cache deferral injection 



Cache deferral injection stress-tests the cache deferral logic as
well as upper layer protocol deferred request handlers. This
facility is for developers and professional testers to ensure
coverage of the rqst deferral code paths. To date, we haven't
had an adequate way to ensure these code paths are covered
during testing, short of temporary code changes to force their
use.

A file called /sys/kernel/debug/fail_sunrpc/ignore-cache-wait
enables administrators to disable cache deferral injection while
allowing other types of sunrpc errors to be injected. The default
setting is that cache deferral injection is enabled (ignore=false).

To enable support for cache deferral injection,
CONFIG_FAULT_INJECTION, CONFIG_FAULT_INJECTION_DEBUG_FS, and
CONFIG_SUNRPC_DEBUG must all be set to "Y".

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 45cb7955

net/sunrpc/cache.c

+17 −1
Original line number Diff line number Diff line
@@ -33,7 +33,9 @@ 
#include <linux/sunrpc/stats.h>

#include <linux/sunrpc/rpc_pipe_fs.h>

#include <trace/events/sunrpc.h>



#include "netns.h"

#include "fail.h"



#define	 RPCDBG_FACILITY RPCDBG_CACHE
@@ -688,16 +690,30 @@ static void cache_limit_defers(void) 
		discard->revisit(discard, 1);

}



#if IS_ENABLED(CONFIG_FAIL_SUNRPC)

static inline bool cache_defer_immediately(void)

{

	return !fail_sunrpc.ignore_cache_wait &&

		should_fail(&fail_sunrpc.attr, 1);

}

#else

static inline bool cache_defer_immediately(void)

{

	return false;

}

#endif



/* Return true if and only if a deferred request is queued. */

static bool cache_defer_req(struct cache_req *req, struct cache_head *item)

{

	struct cache_deferred_req *dreq;



	if (req->thread_wait) {

	if (!cache_defer_immediately()) {

		cache_wait_req(req, item);

		if (!test_bit(CACHE_PENDING, &item->flags))

			return false;

	}



	dreq = req->defer(req);

	if (dreq == NULL)

		return false;

net/sunrpc/debugfs.c

+3 −0
Original line number Diff line number Diff line
@@ -262,6 +262,9 @@ static void fail_sunrpc_init(void) 


	debugfs_create_bool("ignore-server-disconnect", S_IFREG | 0600, dir,

			    &fail_sunrpc.ignore_server_disconnect);



	debugfs_create_bool("ignore-cache-wait", S_IFREG | 0600, dir,

			    &fail_sunrpc.ignore_cache_wait);

}

#else

static void fail_sunrpc_init(void)

net/sunrpc/fail.h

+1 −1
Original line number Diff line number Diff line
@@ -14,8 +14,8 @@ struct fail_sunrpc_attr { 
	struct fault_attr	attr;



	bool			ignore_client_disconnect;



	bool			ignore_server_disconnect;

	bool			ignore_cache_wait;

};



extern struct fail_sunrpc_attr fail_sunrpc;