nl-cache: Fix a possible crash and stale cache

Issue1:
Consider the followinf sequence of operations:
   ...
   nlc_ctx = nlc_ctx_get (inode i1)
   ....... -> nlc_clear_cache (i1) gets called as a part of nlc_invalidate
                                   or any other callers
              ...
              GF_FREE (ii nlc_ctx)
   LOCK (nlc_ctx->lock);  ->  This will result in crash as the ctx
                              got freed in nlc_clear_cache.

Issue2:
   lookup on dir1/file1 result in ENOENT
   add cache to dir1 at time T1
   ....
   CHILD_DOWN at T2
   lookup on dir1/file2 result in ENOENT
   add cache to dir1, but the cache time is still T1
   lookup on dir1/file2 - should have been served from cache
                          but the cache time is T1 < T2, hence
                          cache is considered as invalid.
So, after CHILD_DOWN the right thing would be to clear the cache
and restart caching on that inode.

Solution:
Do not free nlc_ctx in nlc_clear_cache, but only in inode_forget()
The fix for both issue1 and 2 is interleaved hence sending it as
single patch.

Change-Id: I83d8ed36c049a93567c6d7e63d045dc14ccbb397
BUG: 1458539
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: https://review.gluster.org/17453
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/xlators/performance/nl-cache/src/nl-cache.h b/xlators/performance/nl-cache/src/nl-cache.h
index 10ec022d05c..3bd7c83237a 100644
--- a/xlators/performance/nl-cache/src/nl-cache.h
+++ b/xlators/performance/nl-cache/src/nl-cache.h
@@ -44,7 +44,6 @@
 
 enum nlc_cache_clear_reason {
         NLC_NONE = 0,
-        NLC_TIMER_EXPIRED,
         NLC_LRU_PRUNE,
 };