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sunrpc/cache: recheck cache validity after cache_defer_req

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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: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
NeilBrown 2009-08-04 15:22:38 +10:00 committed by J. Bruce Fields
parent 5c4d263903
commit 989a19b9b1
1 changed files with 33 additions and 20 deletions
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53
net/sunrpc/cache.c
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@ -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)
rv = -ETIMEDOUT;
if (rv == -EAGAIN) {
if (cache_defer_req(rqstp, h) == 0) {
/* Request is not deferred */
rv = cache_is_valid(detail, h);
if (rv == -EAGAIN)
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;
@ -594,8 +606,9 @@ 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 0;
return 1;
}
static void cache_revisit_request(struct cache_head *item)