[lvm-devel] master - allocator: fix thin-pool allocation

[Zdenek Kabelac]

Gitweb:        https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=b697aa96466b6a5f479df41a213fc1fd583dc743
Commit:        b697aa96466b6a5f479df41a213fc1fd583dc743
Parent:        c96400b6c7b8ba5124c045a2ae9475e3224ec284
Author:        Zdenek Kabelac <zkabelac at redhat.com>
AuthorDate:    Sun Jul 8 18:34:38 2018 +0200
Committer:     Zdenek Kabelac <zkabelac at redhat.com>
CommitterDate: Mon Jul 9 00:19:30 2018 +0200

allocator: fix thin-pool allocation

When allocating thin-pool with more then 1 device - try to
allocate 'metadataLV' with reuse of log-type allocation for mirror LV.
It should be naturally place on other device then 'dataLV'.

However due to somewhat hard to follow allocation logic code,
it's been rejected allocation in cases where there was not
enough space for data or metadata on single PV, thus to successed,
usage of segments was mandatory.

While user may use:

allocation/thin_pool_metadata_require_separate_pvs=1

to enforce separe meta and data LV - on default settings, this is not
enable thus segment allocation is meant to work.

NOTE:

As already said - the original intention of this whole  'if()' is unclear,
so try to split this test into multiple more simple tests that are more readable.

TODO: more validation.
---
 lib/metadata/lv_manip.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/metadata/lv_manip.c b/lib/metadata/lv_manip.c
index a382e27..b315a87 100644
--- a/lib/metadata/lv_manip.c
+++ b/lib/metadata/lv_manip.c
@@ -2966,12 +2966,14 @@ static int _find_some_parallel_space(struct alloc_handle *ah,
 		       (*(alloc_state->areas + alloc_state->num_positional_areas + ix - 1 -
 			  too_small_for_log_count)).used < ah->log_len)
 			too_small_for_log_count++;
-		ix_log_offset = alloc_state->num_positional_areas + ix - too_small_for_log_count - ah->log_area_count;
+		if (ah->mirror_logs_separate && (too_small_for_log_count >= devices_needed))
+			return 1;
+		if ((alloc_state->num_positional_areas + ix) < (too_small_for_log_count + ah->log_area_count))
+			return 1;
+		ix_log_offset = alloc_state->num_positional_areas + ix - (too_small_for_log_count + ah->log_area_count);
 	}
 
-	if (ix + alloc_state->num_positional_areas < devices_needed +
-	    (alloc_state->log_area_count_still_needed ? alloc_state->log_area_count_still_needed +
-				    too_small_for_log_count : 0))
+	if (ix + alloc_state->num_positional_areas < devices_needed)
 		return 1;
 
 	/*