dmeventd_thin: new logic for calling commands

For more advanced support we need to ensure better logic for calling
external much more advanced script for maintanance of thin-pool.

So this new code ensures:

When thin-pool data or metadata is bigger then 50%,
then with each 5% increment, action is called.
This is independent from autoextend_threshold.
This action always happens when thin-pool is over threshold,
(so no action when it's exactly i.e. 60%).
The only exception is 100% full thin-pool - which invokes 'last'
action.

Since thin-pool occupancy may change also downward, code needs
to also handle possibly reduction of occupancy  of thin-pool.
So when usage drop from 90% to 50%, thin-pool will start to call
again action when it will pass 55% threshold.

This give external commands lot of option i.e. to call 'fstrim'
before actual resize is needed.

diff --git a/daemons/dmeventd/plugins/thin/dmeventd_thin.c b/daemons/dmeventd/plugins/thin/dmeventd_thin.c
index bd70e78fa8a768e23f452e79d702ab65dee4dde4..2367bdeaa9a975ec81afebb41e26e6c4196862cb 100644 (file)
--- a/daemons/dmeventd/plugins/thin/dmeventd_thin.c
+++ b/daemons/dmeventd/plugins/thin/dmeventd_thin.c
@@ -243,21 +243,27 @@ void process_event(struct dm_task *dmt,
                state->fails = 0;
        }
 
+       /*
+        * Trigger action when threshold boundary is exceeded.
+        * Report 80% threshold warning when it's used above 80%.
+        * Only 100% is exception as it cannot be surpased so policy
+        * action is called for:  >50%, >55% ... >95%, 100%
+        */
        state->metadata_percent = dm_make_percent(tps->used_metadata_blocks, tps->total_metadata_blocks);
        if (state->metadata_percent <= WARNING_THRESH)
                state->metadata_warn_once = 0; /* Dropped bellow threshold, reset warn once */
        else if (!state->metadata_warn_once++) /* Warn once when raised above threshold */
                log_warn("WARNING: Thin pool %s metadata is now %.2f%% full.",
                         device, dm_percent_to_float(state->metadata_percent));
-       if (state->metadata_percent >= state->metadata_percent_check) {
-               /*
-                * Usage has raised more than CHECK_STEP since the last
-                * time. Run actions.
-                */
-               state->metadata_percent_check = (state->metadata_percent / CHECK_STEP) * CHECK_STEP + CHECK_STEP;
-
-               needs_policy = 1;
-       }
+       if (state->metadata_percent > CHECK_MINIMUM) {
+               /* Run action when usage raised more than CHECK_STEP since the last time */
+               if (state->metadata_percent > state->metadata_percent_check)
+                       needs_policy = 1;
+               state->metadata_percent_check = (state->metadata_percent / CHECK_STEP + 1) * CHECK_STEP;
+               if (state->metadata_percent_check == DM_PERCENT_100)
+                       state->metadata_percent_check--; /* Can't get bigger then 100% */
+       } else
+               state->metadata_percent_check = CHECK_MINIMUM;
 
        state->data_percent = dm_make_percent(tps->used_data_blocks, tps->total_data_blocks);
        if (state->data_percent <= WARNING_THRESH)
@@ -265,15 +271,15 @@ void process_event(struct dm_task *dmt,
        else if (!state->data_warn_once++)
                log_warn("WARNING: Thin pool %s data is now %.2f%% full.",
                         device, dm_percent_to_float(state->data_percent));
-       if (state->data_percent >= state->data_percent_check) {
-               /*
-                * Usage has raised more than CHECK_STEP since
-                * the last time. Run actions.
-                */
-               state->data_percent_check = (state->data_percent / CHECK_STEP) * CHECK_STEP + CHECK_STEP;
-
-               needs_policy = 1;
-       }
+       if (state->data_percent > CHECK_MINIMUM) {
+               /* Run action when usage raised more than CHECK_STEP since the last time */
+               if (state->data_percent > state->data_percent_check)
+                       needs_policy = 1;
+               state->data_percent_check = (state->data_percent / CHECK_STEP + 1) * CHECK_STEP;
+               if (state->data_percent_check == DM_PERCENT_100)
+                       state->data_percent_check--; /* Can't get bigger then 100% */
+       } else
+               state->data_percent_check = CHECK_MINIMUM;
 
        /* Reduce number of _use_policy() calls by power-of-2 factor till frequency of MAX_FAILS is reached.
         * Avoids too high number of error retries, yet shows some status messages in log regularly.
@@ -372,8 +378,6 @@ int register_device(const char *device,
                _init_thread_signals(state);
        }
 
-       state->metadata_percent_check = CHECK_MINIMUM;
-       state->data_percent_check = CHECK_MINIMUM;
        state->pid = -1;
        *user = state;