From: Alex Ainscow <aainscow@uk.ibm.com>
Date: Thu, 1 May 2025 09:09:15 +0000 (+0100)
Subject: osd: Fix off-by-one error in shard_extent_map.
X-Git-Tag: v20.1.0~68^2~8
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=90627f4ec002536c29b6551a07186df83689da1e;p=ceph.git

osd: Fix off-by-one error in shard_extent_map.

Inserting the first parity buffer was causing the ro-range within the SEM to be incorrectly calculated.
Simple fix and I have added some unit tests to defend this error in the future.

Signed-off-by: Alex Ainscow <aainscow@uk.ibm.com>
(cherry picked from commit 2a569d8680ff64287efea5d4b1790b396aae86cc)
---

diff --git a/src/osd/ECUtil.cc b/src/osd/ECUtil.cc
index 5c5d2828be54..e931e68d086d 100644
--- a/src/osd/ECUtil.cc
+++ b/src/osd/ECUtil.cc
@@ -354,7 +354,7 @@ void shard_extent_map_t::insert_in_shard(shard_id_t shard, uint64_t off,
   extent_maps[shard].insert(off, bl.length(), bl);
   raw_shard_id_t raw_shard = sinfo->get_raw_shard(shard);
 
-  if (raw_shard > sinfo->get_k()) {
+  if (raw_shard >= sinfo->get_k()) {
     return;
   }
 
diff --git a/src/test/osd/TestECUtil.cc b/src/test/osd/TestECUtil.cc
index 71cf3bb614b9..ccf93d312da5 100644
--- a/src/test/osd/TestECUtil.cc
+++ b/src/test/osd/TestECUtil.cc
@@ -1031,4 +1031,53 @@ TEST(ECUtil, slice)
     auto slice_map = sem.slice_map(0, 65*1024);
     ASSERT_EQ(slice_map, sem);
   }
+}
+
+TEST(ECUtil, insert_parity_buffer_into_sem) {
+  int k=2;
+  int m=2;
+  int chunk_size = 4096;
+  stripe_info_t sinfo(k, m, k*chunk_size);
+
+  buffer::list bl1k;
+  buffer::list bl4k;
+  bl1k.append_zero(1024);
+  bl4k.append_zero(4096);
+
+  {
+    shard_extent_map_t sem(&sinfo);
+    sem.insert_in_shard(shard_id_t(2), 0, bl1k);
+    ASSERT_EQ(-1, sem.ro_start);
+    ASSERT_EQ(-1, sem.ro_end);
+  }
+
+  {
+    shard_extent_map_t sem(&sinfo);
+    sem.insert_in_shard(shard_id_t(0), 0, bl4k);
+    ASSERT_EQ(0, sem.ro_start);
+    ASSERT_EQ(4096, sem.ro_end);
+    sem.insert_in_shard(shard_id_t(2), 0, bl4k);
+    ASSERT_EQ(0, sem.ro_start);
+    ASSERT_EQ(4096, sem.ro_end);
+  }
+
+  {
+    shard_extent_map_t sem(&sinfo);
+    sem.insert_in_shard(shard_id_t(1), 0, bl4k);
+    ASSERT_EQ(4096, sem.ro_start);
+    ASSERT_EQ(8192, sem.ro_end);
+    sem.insert_in_shard(shard_id_t(2), 0, bl4k);
+    ASSERT_EQ(4096, sem.ro_start);
+    ASSERT_EQ(8192, sem.ro_end);
+  }
+
+  {
+    shard_extent_map_t sem(&sinfo);
+    sem.insert_in_shard(shard_id_t(1), 0, bl4k);
+    ASSERT_EQ(4096, sem.ro_start);
+    ASSERT_EQ(8192, sem.ro_end);
+    sem.insert_in_shard(shard_id_t(3), 0, bl4k);
+    ASSERT_EQ(4096, sem.ro_start);
+    ASSERT_EQ(8192, sem.ro_end);
+  }
 }
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