4 files changed, 19 insertions, 6 deletions
diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h
index bf3b8ad340e..e57f84ee9c8 100644
--- a/src/include/storage/buf_internals.h
+++ b/src/include/storage/buf_internals.h
@@ -327,8 +327,9 @@ extern int	BufTableInsert(BufferTag *tagPtr, uint32 hashcode, int buf_id);
 extern void BufTableDelete(BufferTag *tagPtr, uint32 hashcode);
 
 /* localbuf.c */
-extern void LocalPrefetchBuffer(SMgrRelation smgr, ForkNumber forkNum,
-								BlockNumber blockNum);
+extern PrefetchBufferResult PrefetchLocalBuffer(SMgrRelation smgr,
+												ForkNumber forkNum,
+												BlockNumber blockNum);
 extern BufferDesc *LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum,
 									BlockNumber blockNum, bool *foundPtr);
 extern void MarkLocalBufferDirty(Buffer buffer);
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index bf3b12a2de3..ee91b8fa26c 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -46,6 +46,15 @@ typedef enum
 								 * replay; otherwise same as RBM_NORMAL */
 } ReadBufferMode;
 
+/*
+ * Type returned by PrefetchBuffer().
+ */
+typedef struct PrefetchBufferResult
+{
+	Buffer		recent_buffer;	/* If valid, a hit (recheck needed!) */
+	bool		initiated_io;	/* If true, a miss resulting in async I/O */
+} PrefetchBufferResult;
+
 /* forward declared, to avoid having to expose buf_internals.h here */
 struct WritebackContext;
 
@@ -162,8 +171,11 @@ extern PGDLLIMPORT int32 *LocalRefCount;
 /*
  * prototypes for functions in bufmgr.c
  */
-extern void PrefetchBuffer(Relation reln, ForkNumber forkNum,
-						   BlockNumber blockNum);
+extern PrefetchBufferResult PrefetchSharedBuffer(struct SMgrRelationData *smgr_reln,
+												 ForkNumber forkNum,
+												 BlockNumber blockNum);
+extern PrefetchBufferResult PrefetchBuffer(Relation reln, ForkNumber forkNum,
+										   BlockNumber blockNum);
 extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
 extern Buffer ReadBufferExtended(Relation reln, ForkNumber forkNum,
 								 BlockNumber blockNum, ReadBufferMode mode,
diff --git a/src/include/storage/md.h b/src/include/storage/md.h
index ec7630ce3b7..07fd1bb7d06 100644
--- a/src/include/storage/md.h
+++ b/src/include/storage/md.h
@@ -28,7 +28,7 @@ extern bool mdexists(SMgrRelation reln, ForkNumber forknum);
 extern void mdunlink(RelFileNodeBackend rnode, ForkNumber forknum, bool isRedo);
 extern void mdextend(SMgrRelation reln, ForkNumber forknum,
 					 BlockNumber blocknum, char *buffer, bool skipFsync);
-extern void mdprefetch(SMgrRelation reln, ForkNumber forknum,
+extern bool mdprefetch(SMgrRelation reln, ForkNumber forknum,
 					   BlockNumber blocknum);
 extern void mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
 				   char *buffer);
diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h
index 79dfe0e373a..bb8428f27f6 100644
--- a/src/include/storage/smgr.h
+++ b/src/include/storage/smgr.h
@@ -93,7 +93,7 @@ extern void smgrdosyncall(SMgrRelation *rels, int nrels);
 extern void smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo);
 extern void smgrextend(SMgrRelation reln, ForkNumber forknum,
 					   BlockNumber blocknum, char *buffer, bool skipFsync);
-extern void smgrprefetch(SMgrRelation reln, ForkNumber forknum,
+extern bool smgrprefetch(SMgrRelation reln, ForkNumber forknum,
 						 BlockNumber blocknum);
 extern void smgrread(SMgrRelation reln, ForkNumber forknum,
 					 BlockNumber blocknum, char *buffer);