rda, glusterd: Change the max of rda-cache-limit to INFINITY

Issue:
The max value of rda-cache-limit is 1GB before this patch.
When parallel-readdir is enabled, there will be many instances of
readdir-ahead, hence the rda-cache-limit depends on the number of
instances. Eg: On a volume with distribute count 4, rda-cache-limit
when parallel-readdir is enabled, will be 4GB instead of 1GB.
Consider a followinf sequence of operations:
- Enable parallel readdir
- Set rda-cache-limit to lets say 3GB
- Disable parallel-readdir, this results in one instance of readdir-ahead
  and the rda-cache-limit will be back to 1GB, but the current value is 3GB
  and hence the mount will stop working as 3GB > max 1GB.

Solution:
To fix this, we can limit the cache to 1GB even when parallel-readdir
is enabled. But there is no necessity to limit the cache to 1GB, it
can be increased if the system has enough resources. Hence getting rid
of the rda-cache-limit max value is more apt. If we just change the
rda-cache-limit max to INFINITY, we will render older(<3.11) clients
broken, when the rda-cache-limit is set to > 1GB (as the older clients
still expect a value < 1GB). To safely change the max value of
rda-cache-limit to INFINITY, add a check in glusted to verify all
the clients are > 3.11 if the value exceeds 1GB.

Change-Id: Id0cdda3b053287b659c7bf511b13db2e45b92032
BUG: 1446516
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: https://review.gluster.org/17338
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

2 files changed, 22 insertions, 1 deletions

diff --git a/tests/bugs/readdir-ahead/bug-1439640.t b/tests/bugs/readdir-ahead/bug-1439640.t
index cfa5d1ff659..cc6c829fccc 100755
--- a/tests/bugs/readdir-ahead/bug-1439640.t
+++ b/tests/bugs/readdir-ahead/bug-1439640.t
@@ -27,4 +27,4 @@ TEST ! $CLI volume set $V0 rda-request-size 87adh
 TEST $CLI volume set $V0 rda-cache-limit 10MB
 TEST $CLI volume set $V0 rda-request-size 128KB
 
-#cleanup;
+cleanup;
diff --git a/tests/bugs/readdir-ahead/bug-1446516.t b/tests/bugs/readdir-ahead/bug-1446516.t
new file mode 100755
index 00000000000..2bf6520d861
--- /dev/null
+++ b/tests/bugs/readdir-ahead/bug-1446516.t
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+
+cleanup;
+
+TEST glusterd
+
+TEST $CLI volume create $V0 $H0:$B0/${V0}{1..4}
+TEST $CLI volume start $V0
+
+TEST $CLI volume set $V0 parallel-readdir on
+
+TEST $CLI volume set $V0 rda-cache-limit 4GB
+
+TEST $CLI volume set $V0 parallel-readdir off
+
+TEST glusterfs --volfile-server=$H0 --volfile-id=$V0 $M0
+
+cleanup;