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thin: improve recognizing of merge in progress

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Rewrite too condensed condition in more readable form,
wher decision are clearly separated and commented and
also add debug messages for them.
This commit is contained in:
Zdenek Kabelac 2016-04-18 11:04:16 +02:00
parent e2cd882f2e
commit 9cccf5245a
1 changed files with 42 additions and 15 deletions
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57
lib/activate/dev_manager.c
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@ -2764,25 +2764,52 @@ static int _add_new_lv_to_dtree(struct dev_manager *dm, struct dm_tree *dtree,
/*
* Clear merge attributes if merge isn't currently possible:
* either origin or merging snapshot are open
* - but use "snapshot-merge" if it is already in use
* - for old snaps use "snapshot-merge" if it is already in use
* - open_count is always retrieved (as of dm-ioctl 4.7.0)
* so just use the tree's existing nodes' info
*/
/* An activating merging origin won't have a node in the tree yet */
if (((dinfo = _cached_dm_info(dm->mem, dtree, lv, NULL)) &&
dinfo->open_count) ||
((dinfo = _cached_dm_info(dm->mem, dtree,
seg_is_thin_volume(seg) ?
seg->lv : seg->cow, NULL)) &&
dinfo->open_count))
snap_dev_is_open = 1;
if ((dinfo = _cached_dm_info(dm->mem, dtree,
seg_is_thin_volume(seg) ?
seg->lv : seg->cow, NULL))) {
if (seg_is_thin_volume(seg)) {
/* Active thin snapshot prevents merge */
log_debug_activation("Merging thin snapshot %s is active.",
display_lvname(seg->lv));
} else if (dinfo->open_count) {
log_debug_activation("Merging snapshot LV %s is openned.",
display_lvname(seg->lv));
snap_dev_is_open = 1;
}
}
/* Preload considers open devices. */
/* Resume looks at the table that will be the live one after the operation. */
if ((!laopts->resuming && snap_dev_is_open && (seg_is_thin_volume(seg) || !lv_has_target_type(dm->mem, lv, NULL, TARGET_NAME_SNAPSHOT_MERGE))) ||
(laopts->resuming &&
((!seg_is_thin_volume(seg) && !lv_has_target_type(dm->mem, lv, NULL, TARGET_NAME_SNAPSHOT_MERGE)) ||
(seg_is_thin_volume(seg) && !_thin_lv_has_device_id(dm->mem, lv, NULL, seg->device_id))))) {
if ((dinfo = _cached_dm_info(dm->mem, dtree, lv, NULL))) {
if (dinfo->open_count) {
log_debug_activation("Merging origin volume %s is openned.", display_lvname(seg->lv));
snap_dev_is_open = 1;
}
/* Check if decision needs to be preserved.
* Merging origin LV needs to be present in table in this case. */
if (!laopts->resuming) {
if ((seg_is_thin_volume(seg) && _thin_lv_has_device_id(dm->mem, lv, NULL, seg->device_id)) ||
(!seg_is_thin_volume(seg) && lv_has_target_type(dm->mem, lv, NULL, TARGET_NAME_SNAPSHOT_MERGE))) {
log_debug_activation("Merging of snapshot volume %s is in progress.",
display_lvname(seg->lv));
/* Merging is already running and cannot be switched */
snap_dev_is_open = 0;
}
} else {
if ((seg_is_thin_volume(seg) && !_thin_lv_has_device_id(dm->mem, lv, NULL, seg->device_id)) ||
(!seg_is_thin_volume(seg) && !lv_has_target_type(dm->mem, lv, NULL, TARGET_NAME_SNAPSHOT_MERGE))) {
log_debug_activation("Merging of snapshot volume %s was not started before suspend.",
display_lvname(seg->lv));
/* Merging targe table cannot be reloaded when suspend */
snap_dev_is_open = 1;
}
}
}
if (snap_dev_is_open) {
log_debug_activation("Postponing pending snapshot merge for origin LV %s.", display_lvname(lv));
laopts->no_merging = 1;
}