cluster/ec: Improve detection of new heals

When EC successfully healed a directory it assumed that maybe other
entries inside that directory could have been created, which could
require additional heal cycles. For this reason, when the heal happened
as part of one index heal iteration, it triggered a new iteration.

The problem happened when the directory was healthy, so no new entries
were added, but its index entry was not removed for some reason. In
this case self-heal started and endless loop healing the same directory
continuously, cause high CPU utilization.

This patch improves detection of new files added to the heal index so
that a new index heal iteration is only triggered if there is new work
to do.

Change-Id: I2355742b85fbfa6de758bccc5d2e1a283c82b53f
Fixes: #1354
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

1 files changed, 25 insertions, 2 deletions

diff --git a/xlators/cluster/ec/src/ec-inode-read.c b/xlators/cluster/ec/src/ec-inode-read.c
index a891ccd0952..dad5f4d7018 100644
--- a/xlators/cluster/ec/src/ec-inode-read.c
+++ b/xlators/cluster/ec/src/ec-inode-read.c
@@ -390,7 +390,8 @@ ec_manager_getxattr(ec_fop_data_t *fop, int32_t state)
 int32_t
 ec_getxattr_heal_cbk(call_frame_t *frame, void *cookie, xlator_t *xl,
                      int32_t op_ret, int32_t op_errno, uintptr_t mask,
-                     uintptr_t good, uintptr_t bad, dict_t *xdata)
+                     uintptr_t good, uintptr_t bad, uint32_t pending,
+                     dict_t *xdata)
 {
     fop_getxattr_cbk_t func = cookie;
     ec_t *ec = xl->private;
@@ -398,6 +399,25 @@ ec_getxattr_heal_cbk(call_frame_t *frame, void *cookie, xlator_t *xl,
     char *str;
     char bin1[65], bin2[65];
 
+    /* We try to return the 'pending' information in xdata, but if this cannot
+     * be set, we will ignore it silently. We prefer to report the success or
+     * failure of the heal itself. */
+    if (xdata == NULL) {
+        xdata = dict_new();
+    } else {
+        dict_ref(xdata);
+    }
+    if (xdata != NULL) {
+        if (dict_set_uint32(xdata, EC_XATTR_HEAL_NEW, pending) != 0) {
+            /* dict_set_uint32() is marked as 'warn_unused_result' and gcc
+             * enforces to check the result in this case. However we don't
+             * really care if it succeeded or not. We'll just do the same.
+             *
+             * This empty 'if' avoids the warning, and it will be removed by
+             * the optimizer. */
+        }
+    }
+
     if (op_ret >= 0) {
         dict = dict_new();
         if (dict == NULL) {
@@ -431,11 +451,14 @@ ec_getxattr_heal_cbk(call_frame_t *frame, void *cookie, xlator_t *xl,
     }
 
 out:
-    func(frame, NULL, xl, op_ret, op_errno, dict, NULL);
+    func(frame, NULL, xl, op_ret, op_errno, dict, xdata);
 
     if (dict != NULL) {
         dict_unref(dict);
     }
+    if (xdata != NULL) {
+        dict_unref(xdata);
+    }
 
     return 0;
 }