src/patches/suse-2.6.27.31/patches.fixes/nfsd-02-sunrpc-cache-recheck-cache-validity-after-cache_defe.patch

   1 Patch-mainline: submitted 04aug2009
   2 References: bnc#498708
   3 From: NeilBrown <neilb@suse.de>
   4 Date: Tue, 4 Aug 2009 15:06:37 +1000
   5 Subject: [PATCH 04/12] sunrpc/cache: recheck cache validity after cache_defer_req
   6
   7 If cache_defer_req did not leave the request on a queue, then it could
   8 possibly have waited long enough that the cache became valid.  So check the
   9 status after the call.
  10
  11 Signed-off-by: NeilBrown <neilb@suse.de>
  12
  13 ---
  14  net/sunrpc/cache.c |   53 +++++++++++++++++++++++++++++++++--------------------
  15  1 file changed, 33 insertions(+), 20 deletions(-)
  16
  17 --- linux-2.6.27-SLE11_BRANCH.orig/net/sunrpc/cache.c
  18 +++ linux-2.6.27-SLE11_BRANCH/net/sunrpc/cache.c
  19 @@ -173,6 +173,22 @@ struct cache_head *sunrpc_cache_update(s
  20  EXPORT_SYMBOL(sunrpc_cache_update);
  21
  22  static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
  23 +
  24 +static inline int cache_is_valid(struct cache_detail *detail, struct cache_head *h)
  25 +{
  26 +       if (!test_bit(CACHE_VALID, &h->flags) ||
  27 +           h->expiry_time < get_seconds())
  28 +               return -EAGAIN;
  29 +       else if (detail->flush_time > h->last_refresh)
  30 +               return -EAGAIN;
  31 +       else {
  32 +               /* entry is valid */
  33 +               if (test_bit(CACHE_NEGATIVE, &h->flags))
  34 +                       return -ENOENT;
  35 +               else
  36 +                       return 0;
  37 +       }
  38 +}
  39  /*
  40   * This is the generic cache management routine for all
  41   * the authentication caches.
  42 @@ -181,8 +197,10 @@ static int cache_make_upcall(struct cach
  43   *
  44   *
  45   * Returns 0 if the cache_head can be used, or cache_puts it and returns
  46 - * -EAGAIN if upcall is pending,
  47 - * -ETIMEDOUT if upcall failed and should be retried,
  48 + * -EAGAIN if upcall is pending and request has been queued
  49 + * -ETIMEDOUT if upcall failed or request could not be queue or
  50 + *           upcall completed but item is still invalid (implying that
  51 + *           the cache item has been replaced with a newer one).
  52   * -ENOENT if cache entry was negative
  53   */
  54  int cache_check(struct cache_detail *detail,
  55 @@ -192,17 +210,7 @@ int cache_check(struct cache_detail *det
  56         long refresh_age, age;
  57
  58         /* First decide return status as best we can */
  59 -       if (!test_bit(CACHE_VALID, &h->flags) ||
  60 -           h->expiry_time < get_seconds())
  61 -               rv = -EAGAIN;
  62 -       else if (detail->flush_time > h->last_refresh)
  63 -               rv = -EAGAIN;
  64 -       else {
  65 -               /* entry is valid */
  66 -               if (test_bit(CACHE_NEGATIVE, &h->flags))
  67 -                       rv = -ENOENT;
  68 -               else rv = 0;
  69 -       }
  70 +       rv = cache_is_valid(detail, h);
  71
  72         /* now see if we want to start an upcall */
  73         refresh_age = (h->expiry_time - h->last_refresh);
  74 @@ -234,10 +242,14 @@ int cache_check(struct cache_detail *det
  75                 }
  76         }
  77
  78 -       if (rv == -EAGAIN)
  79 -               if (cache_defer_req(rqstp, h) != 0)
  80 -                       rv = -ETIMEDOUT;
  81 -
  82 +       if (rv == -EAGAIN) {
  83 +               if (cache_defer_req(rqstp, h) == 0) {
  84 +                       /* Request is not deferred */
  85 +                       rv = cache_is_valid(detail, h);
  86 +                       if (rv == -EAGAIN)
  87 +                               rv = -ETIMEDOUT;
  88 +               }
  89 +       }
  90         if (rv)
  91                 cache_put(h, detail);
  92         return rv;
  93 @@ -558,11 +570,11 @@ static int cache_defer_req(struct cache_
  94                  * or continue and drop the oldest below
  95                  */
  96                 if (net_random()&1)
  97 -                       return -ETIMEDOUT;
  98 +                       return 0;
  99         }
 100         dreq = req->defer(req);
 101         if (dreq == NULL)
 102 -               return -ETIMEDOUT;
 103 +               return 0;
 104
 105         dreq->item = item;
 106
 107 @@ -592,8 +604,9 @@ static int cache_defer_req(struct cache_
 108         if (!test_bit(CACHE_PENDING, &item->flags)) {
 109                 /* must have just been validated... */
 110                 cache_revisit_request(item);
 111 +               return 0;
 112         }
 113 -       return 0;
 114 +       return 1;
 115  }
 116
 117  static void cache_revisit_request(struct cache_head *item)