Fix bug in GetLastWrittenLSNv

Author: Konstantin Knizhnik

src/backend/access/transam/xlog.c

@@ -6760,6 +6760,7 @@ GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
 				   BlockNumber blkno, int nblocks, XLogRecPtr *lsns)
 {
 	LastWrittenLsnCacheEntry* entry;
+	XLogRecPtr lsn;
 
 	Assert(lastWrittenLsnCacheSize != 0);
 	Assert(nblocks > 0);
@@ -6785,7 +6786,7 @@ GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
 			entry = hash_search(lastWrittenLsnCache, &key, HASH_FIND, NULL);
 			if (entry != NULL)
 			{
-				lsns[i] = entry->lsn;
+ 				lsns[i] = entry->lsn;
 			}
 			else
 			{
@@ -6804,19 +6805,22 @@ GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
 			LWLockRelease(LastWrittenLsnLock);
 			LWLockAcquire(LastWrittenLsnLock, LW_EXCLUSIVE);
 
+			lsn = XLogCtl->maxLastWrittenLsn;
+
 			for (int i = 0; i < nblocks; i++)
 			{
 				if (lsns[i] == InvalidXLogRecPtr)
 				{
-					SetLastWrittenLSNForBlockRangeInternal(XLogCtl->maxLastWrittenLsn, relfilenode, forknum, blkno + i, 1);
+					lsns[i] = lsn;
+					SetLastWrittenLSNForBlockRangeInternal(lsn, relfilenode, forknum, blkno + i, 1);
 				}
 			}
 		}
 	}
 	else
 	{
 		HASH_SEQ_STATUS seq;
-		XLogRecPtr lsn = XLogCtl->maxLastWrittenLsn;
+		lsn = XLogCtl->maxLastWrittenLsn;
 		/* Find maximum of all cached LSNs */
 		hash_seq_init(&seq, lastWrittenLsnCache);
 		while ((entry = (LastWrittenLsnCacheEntry *) hash_seq_search(&seq)) != NULL)