From: myoungwon oh <ohmyoungwon@gmail.com>
Date: Thu, 21 Aug 2025 06:03:07 +0000 (+0000)
Subject: crimson/os/seastore: correct possible mergeable size for ool extents
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=552499f86b6bf7cdf7f42ecf8e960edf85f56380;p=ceph.git

crimson/os/seastore: correct possible mergeable size for ool extents

Current implementation only checks a previous ool extent
before writing a ool extent. This can miss merge opportunities
for extents that are sequential but precede the last OOL extent.

This commit fixes this by reporting a correct mergeable size.

Signed-off-by: Myoungwon Oh <ohmyoungwon@gmail.com>
---

diff --git a/src/crimson/os/seastore/extent_placement_manager.cc b/src/crimson/os/seastore/extent_placement_manager.cc
index be53c9c292c1..b7572a366f97 100644
--- a/src/crimson/os/seastore/extent_placement_manager.cc
+++ b/src/crimson/os/seastore/extent_placement_manager.cc
@@ -1068,7 +1068,7 @@ RandomBlockOolWriter::do_write(
 
     // TODO : allocate a consecutive address based on a transaction
     if (writes.size() != 0 &&
-        writes.back().offset + writes.back().bp.length() == paddr) {
+	writes.back().offset + writes.back().get_mergeable_length() == paddr) {
       // We can write both the currrent extent and the previous one at once
       // if the extents are located in a row
       if (writes.back().mergeable_bps.size() == 0) {
diff --git a/src/crimson/os/seastore/extent_placement_manager.h b/src/crimson/os/seastore/extent_placement_manager.h
index 95378d558e62..d5361359a56a 100644
--- a/src/crimson/os/seastore/extent_placement_manager.h
+++ b/src/crimson/os/seastore/extent_placement_manager.h
@@ -195,6 +195,17 @@ private:
     ceph::bufferptr bp;
     RandomBlockManager* rbm;
     std::list<ceph::bufferptr> mergeable_bps;
+
+    extent_len_t get_mergeable_length() const {
+      if (mergeable_bps.size() == 0) {
+	return bp.length();
+      }
+      extent_len_t len = 0;
+      for (auto &p : mergeable_bps) {
+	len += p.length();
+      }
+      return len;
+    }
   };
   alloc_write_iertr::future<> do_write(
     Transaction& t,