deactivation: reduce ioctl count

When LV is deactivativate, we check for presence, and later
for some LV types also for being in use.

We can however do this check in 1 step for them a remove extra ioctl.

Add return value '2' to lv_check_not_in_use() to recognize LV is not
present.

Existing users were just testing for 0, so no change for them.

diff --git a/lib/activate/activate.c b/lib/activate/activate.c
index 75248aa63a3b301b682c6d5fcb8488f466854a2f..a56227118eca42f25e2a9871c07b51a8bda97a43 100644 (file)
--- a/lib/activate/activate.c
+++ b/lib/activate/activate.c
@@ -828,13 +828,14 @@ int lv_info_with_seg_status(struct cmd_context *cmd,
 #define OPEN_COUNT_CHECK_USLEEP_DELAY 200000
 
 /* Only report error if error_if_used is set */
+/* Returns 0 if in use,  1 if it is unused, 2 when it is not present in table */
 int lv_check_not_in_use(const struct logical_volume *lv, int error_if_used)
 {
        struct lvinfo info;
        unsigned int open_count_check_retries;
 
        if (!lv_info(lv->vg->cmd, lv, 0, &info, 1, 0) || !info.exists || !info.open_count)
-               return 1;
+               return !info.exists ? 2 : 1;
 
        /* If sysfs is not used, use open_count information only. */
        if (dm_sysfs_dir()) {
@@ -2408,44 +2409,47 @@ int lv_deactivate(struct cmd_context *cmd, const char *lvid_s, const struct logi
 
        log_debug_activation("Deactivating %s.", display_lvname(lv));
 
-       if (!lv_info(cmd, lv, 0, &info, 0, 0))
-               goto_out;
-
-       if (!info.exists) {
-               r = 1;
-               /* Check attached snapshot segments are also inactive */
-               dm_list_iterate(snh, &lv->snapshot_segs) {
-                       if (!lv_info(cmd, dm_list_struct_base(snh, struct lv_segment, origin_list)->cow,
-                                    0, &info, 0, 0))
-                               goto_out;
-                       if (info.exists) {
-                               r = 0; /* Snapshot left in table? */
-                               break;
-                       }
+       if (lv_is_visible(lv) || lv_is_virtual_origin(lv) ||
+           lv_is_merging_thin_snapshot(lv)) {
+               switch (lv_check_not_in_use(lv, 1)) {
+               case 0: goto_out;
+               case 2: goto no_exists;
                }
 
-               if (lv_is_vdo_pool(lv)) {
-                       /* If someone has remove 'linear' mapping over VDO device
-                        * we may still be able to deactivate the rest of the tree
-                        * i.e. in test-suite we simulate this via 'dmsetup remove' */
-                       if (!lv_info(cmd, lv, 1, &info, 1, 0))
-                               goto_out;
+               if (lv_is_origin(lv) && _lv_has_open_snapshots(lv))
+                       goto_out;
+       } else {
+               if (!lv_info(cmd, lv, 0, &info, 0, 0))
+                       goto_out;
 
-                       if (info.exists && !info.open_count)
-                               r = 0; /* Unused VDO device left in table? */
-               }
+               if (!info.exists) {
+       no_exists:
+                       r = 1;
+                       /* Check attached snapshot segments are also inactive */
+                       dm_list_iterate(snh, &lv->snapshot_segs) {
+                               if (!lv_info(cmd, dm_list_struct_base(snh, struct lv_segment, origin_list)->cow,
+                                            0, &info, 0, 0))
+                                       goto_out;
+                               if (info.exists) {
+                                       r = 0; /* Snapshot left in table? */
+                                       break;
+                               }
+                       }
 
-               if (r)
-                       goto out;
-       }
+                       if (lv_is_vdo_pool(lv)) {
+                               /* If someone has remove 'linear' mapping over VDO device
+                                * we may still be able to deactivate the rest of the tree
+                                * i.e. in test-suite we simulate this via 'dmsetup remove' */
+                               if (!lv_info(cmd, lv, 1, &info, 1, 0))
+                                       goto_out;
 
-       if (lv_is_visible(lv) || lv_is_virtual_origin(lv) ||
-           lv_is_merging_thin_snapshot(lv)) {
-               if (!lv_check_not_in_use(lv, 1))
-                       goto_out;
+                               if (info.exists && !info.open_count)
+                                       r = 0; /* Unused VDO device left in table? */
+                       }
 
-               if (lv_is_origin(lv) && _lv_has_open_snapshots(lv))
-                       goto_out;
+                       if (r)
+                               goto out;
+               }
        }
 
        if (!monitor_dev_for_events(cmd, lv, &laopts, 0))