features/quota: Improvements to quota

* Two stages of quota enforcement is done:

  Soft and hard quota Upon reaching soft quota limit on the directory
  it logs/alerts in the quota daemon log (ie DEFAULT_LOG_DIR/quotad.log)
  and no more writes allowed after hard
  quota limit. After reaching the soft-limit the daemon alerts the
  user/admin repeatively for every 'alert-time', which is
  configurable.

* Quota enforcer is moved to server-side.

  It  takes care of enforcing quota. Since enforcer doesn't have the
  cluster view, it relies on another service called
  quota-aggregator. Aggregator, on query can return the size of a
  directory based on the cluster view.

  Enforcer is always loaded in the server graph and is by passed if
  the feature is not enabled.

  Options specific to enforcer:

  server-quota - Specifies whether the feature is on/off. It is used
  to by pass the quota if turned off.

  deem-statfs - If set to on, it takes quota limits into consideration
  while estimating fs size. (df command). The algorithm followed is,
  i.   Adjust statvfs based on limit configured on root.
  ii.  If limit is set on the inode passed, use size/limits on that inode to
       populate statvfs. Otherwise, use size/limits configured on root.
  iii. Upon statvfs, update the ctx->size on the inode.
  iv.  Don't let DHT aggregate, instead take the maximum of the usages from the
       subvols of the DHT, since each of it contains the complete information.

  Enforcer also makes use of gfid-to-path conversion functionality to
  work correctly when a client like nfs predominently relies on
  nameless lookups.

* Quota Aggregator acts as a thin client to provide cluster view

  Its a lightweight *gluster client* process with no mount point,
  started upon enabling quota or restarting the volume. This is a
  single process run on each brick, which can answer queries on all
  volumes in the cluster. Its volfile stored in
  GLUSTERD_DEFAULT_WORKING_DIR/quotad/quotad.vol.

Credits:
Raghavendra Bhat        <rabhat@redhat.com>
Varun Shastry           <vshastry@redhat.com>
Shishir Gowda           <sgowda@redhat.com>
Kruthika Dhananjay      <kdhananj@redhat.com>
Brian Foster            <bfoster@redhat.com>
Krishnan Parthasarathi  <kparthas@redhat.com>

Change-Id: Id1cb25b414951da34c665a55f77385d482e0f9de
BUG: 969461
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on: http://review.gluster.org/5952
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/libglusterfs/src/dict.h b/libglusterfs/src/dict.h
index 9b41b5a7df0..6e5d8aa0650 100644
--- a/libglusterfs/src/dict.h
+++ b/libglusterfs/src/dict.h
@@ -179,7 +179,8 @@ int dict_foreach_fnmatch (dict_t *dict, char *pattern,
 
 int dict_null_foreach_fn (dict_t *d, char *k,
                           data_t *v, void *tmp);
-
+int dict_remove_foreach_fn (dict_t *d, char *k,
+                            data_t *v, void *tmp);
 dict_t *dict_copy (dict_t *this, dict_t *new);
 int dict_keys_join (void *value, int size, dict_t *dict,
                     int (*filter_fn)(char *key));