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Commit 989a19b9 authored by NeilBrown's avatar NeilBrown Committed by J. Bruce Fields
Browse files

sunrpc/cache: recheck cache validity after cache_defer_req 



If cache_defer_req did not leave the request on a queue, then it could
possibly have waited long enough that the cache became valid.  So check the
status after the call.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
parent 5c4d2639

net/sunrpc/cache.c

+33 −20
Original line number Diff line number Diff line
@@ -176,6 +176,22 @@ struct cache_head *sunrpc_cache_update(struct cache_detail *detail, 
EXPORT_SYMBOL_GPL(sunrpc_cache_update);



static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);



static inline int cache_is_valid(struct cache_detail *detail, struct cache_head *h)

{

	if (!test_bit(CACHE_VALID, &h->flags) ||

	    h->expiry_time < get_seconds())

		return -EAGAIN;

	else if (detail->flush_time > h->last_refresh)

		return -EAGAIN;

	else {

		/* entry is valid */

		if (test_bit(CACHE_NEGATIVE, &h->flags))

			return -ENOENT;

		else

			return 0;

	}

}

/*

 * This is the generic cache management routine for all

 * the authentication caches.
@@ -184,8 +200,10 @@ static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h); 
 *

 *

 * Returns 0 if the cache_head can be used, or cache_puts it and returns

 * -EAGAIN if upcall is pending,

 * -ETIMEDOUT if upcall failed and should be retried,

 * -EAGAIN if upcall is pending and request has been queued

 * -ETIMEDOUT if upcall failed or request could not be queue or

 *           upcall completed but item is still invalid (implying that

 *           the cache item has been replaced with a newer one).

 * -ENOENT if cache entry was negative

 */

int cache_check(struct cache_detail *detail,
@@ -195,17 +213,7 @@ int cache_check(struct cache_detail *detail, 
	long refresh_age, age;



	/* First decide return status as best we can */

	if (!test_bit(CACHE_VALID, &h->flags) ||

	    h->expiry_time < get_seconds())

		rv = -EAGAIN;

	else if (detail->flush_time > h->last_refresh)

		rv = -EAGAIN;

	else {

		/* entry is valid */

		if (test_bit(CACHE_NEGATIVE, &h->flags))

			rv = -ENOENT;

		else rv = 0;

	}

	rv = cache_is_valid(detail, h);



	/* now see if we want to start an upcall */

	refresh_age = (h->expiry_time - h->last_refresh);
@@ -238,10 +246,14 @@ int cache_check(struct cache_detail *detail, 
		}

	}



	if (rv == -EAGAIN) {

		if (cache_defer_req(rqstp, h) == 0) {

			/* Request is not deferred */

			rv = cache_is_valid(detail, h);

			if (rv == -EAGAIN)

		if (cache_defer_req(rqstp, h) != 0)

				rv = -ETIMEDOUT;



		}

	}

	if (rv)

		cache_put(h, detail);

	return rv;
@@ -560,11 +572,11 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) 
		 * or continue and drop the oldest below

		 */

		if (net_random()&1)

			return -ETIMEDOUT;

			return 0;

	}

	dreq = req->defer(req);

	if (dreq == NULL)

		return -ETIMEDOUT;

		return 0;



	dreq->item = item;
@@ -594,9 +606,10 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) 
	if (!test_bit(CACHE_PENDING, &item->flags)) {

		/* must have just been validated... */

		cache_revisit_request(item);

	}

		return 0;

	}

	return 1;

}



static void cache_revisit_request(struct cache_head *item)

{