From 2db8184cd86a0a134e94b4bce9338f5ebbbd3b8e Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Wed, 6 Aug 2025 01:42:33 +0300
Subject: [PATCH] Fix bitmap calculation for EC N+1 & the new store and EC N+2+
 for the old store

---
 src/osd/osd_rmw.cpp      | 28 ++++++++++++++++++++++++----
 src/osd/osd_rmw_test.cpp |  4 ++--
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/osd/osd_rmw.cpp b/src/osd/osd_rmw.cpp
index 9040ddc7..29022aab 100644
--- a/src/osd/osd_rmw.cpp
+++ b/src/osd/osd_rmw.cpp
@@ -21,16 +21,31 @@ extern "C" {
 
 static inline void extend_read(uint32_t start, uint32_t end, osd_rmw_stripe_t & stripe)
 {
-    if (stripe.read_end == 0)
+    if (end == UINT32_MAX)
+    {
+        // UINT32_MAX means that the stripe only needs bitmap
+        if (!stripe.read_end)
+        {
+            stripe.read_start = 0;
+            stripe.read_end = UINT32_MAX;
+        }
+    }
+    else if (stripe.read_end == UINT32_MAX)
+    {
+        if (end > 0)
+        {
+            stripe.read_start = start;
+            stripe.read_end = end;
+        }
+    }
+    else if (stripe.read_end == 0)
     {
         stripe.read_start = start;
         stripe.read_end = end;
     }
     else
     {
-        if (stripe.read_end < end && end != UINT32_MAX ||
-            // UINT32_MAX means that stripe only needs bitmap, end != 0 => needs also data
-            stripe.read_end == UINT32_MAX && end != 0)
+        if (stripe.read_end < end)
             stripe.read_end = end;
         if (stripe.read_start > start)
             stripe.read_start = start;
@@ -664,6 +679,11 @@ void* calc_rmw(void *request_buf, osd_rmw_stripe_t *stripes, uint64_t *read_osd_
         for (int role = 0; role < pg_minsize; role++)
         {
             cover_read(start, end, stripes[role]);
+            if (!stripes[role].read_end && (stripes[role].req_start != 0 || stripes[role].req_end != chunk_size))
+            {
+                // Read bitmaps even if we don't need data but it's not fully overwritten
+                stripes[role].read_end = UINT32_MAX;
+            }
         }
     }
     if (write_osd_set != read_osd_set)
diff --git a/src/osd/osd_rmw_test.cpp b/src/osd/osd_rmw_test.cpp
index f7002ef0..c936ccc8 100644
--- a/src/osd/osd_rmw_test.cpp
+++ b/src/osd/osd_rmw_test.cpp
@@ -897,7 +897,7 @@ void test14()
 15. EC 2+2 partial overwrite with 1 missing stripe
    calc_rmw(offset=64K+28K, len=4K, osd_set=[1,2,3,0], write_set=[1,2,3,0])
    = {
-     read: [ [ 28K, 32K ], [ 0, 0 ], [ 0, 0 ], [ 0, 0 ] ],
+     read: [ [ 28K, 32K ], [ 0, -1 (BITMAP ONLY) ], [ 0, 0 ], [ 0, 0 ] ],
      write: [ [ 0, 0 ], [ 28K, 32K ], [ 28K, 32K ], [ 0, 0 ] ],
      input buffer: [ write1 ],
      rmw buffer: [ write2, read0 ],
@@ -925,7 +925,7 @@ void test15(bool second)
         stripes[i].bmp_buf = bitmaps+i;
     assert(rmw_buf);
     assert(stripes[0].read_start == 28*1024 && stripes[0].read_end == 32*1024);
-    assert(stripes[1].read_start == 0 && stripes[1].read_end == 0);
+    assert(stripes[1].read_start == 0 && stripes[1].read_end == UINT32_MAX);
     assert(stripes[2].read_start == 0 && stripes[2].read_end == 0);
     assert(stripes[3].read_start == 0 && stripes[3].read_end == 0);
     assert(stripes[0].write_start == 0 && stripes[0].write_end == 0);