From: Igor Fedotov <igor.fedotov@croit.io>
Date: Wed, 16 Feb 2022 21:13:45 +0000 (+0300)
Subject: os/bluestore: fix edge case for bitmap alloc's claim_free_to_left(0)
X-Git-Url: http://git.apps.os.sepia.ceph.com/?a=commitdiff_plain;h=7bc78aa857738a69f0e4c2ad81d702c6f5e7dffd;p=ceph.git

os/bluestore: fix edge case for bitmap alloc's claim_free_to_left(0)
call.

This imporperly marked the first 64 chunks as allocated.
Apaprently not critical for production since offset(0) is never
released.

Signed-off-by: Igor Fedotov <igor.fedotov@croit.io>
---

diff --git a/src/os/bluestore/fastbmap_allocator_impl.cc b/src/os/bluestore/fastbmap_allocator_impl.cc
index 4f735ba2efeeb..4833b9d1a7b78 100644
--- a/src/os/bluestore/fastbmap_allocator_impl.cc
+++ b/src/os/bluestore/fastbmap_allocator_impl.cc
@@ -623,7 +623,7 @@ uint64_t AllocatorLevel01Loose::_claim_free_to_left_l0(int64_t l0_pos_start)
 {
   int64_t d0 = L0_ENTRIES_PER_SLOT;
 
-  int64_t pos = l0_pos_start - 1;
+  int64_t pos = l0_pos_start ? l0_pos_start - 1 : 0;
   slot_t bits = (slot_t)1 << (pos % d0);
   int64_t idx = pos / d0;
   slot_t* val_s = l0.data() + idx;