From f736deb8ccb00157866ad37f692ebf6730e441c2 Mon Sep 17 00:00:00 2001
From: Dilip Kumar <dilipkumar@localhost.localdomain>
Date: Fri, 24 Sep 2021 18:23:39 +0530
Subject: [PATCH v3 4/6] Extend bufmgr interfaces

Extend ReadBufferWithoutRelcache interface to take relpersistence as
and input and extend DropDatabaseBuffers to take tablespace oid as
input.
---
 src/backend/storage/buffer/bufmgr.c | 24 +++++++++++-------------
 src/include/storage/bufmgr.h        |  5 +++--
 2 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index e88e4e918b..ed54c34031 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -770,24 +770,17 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
 /*
  * ReadBufferWithoutRelcache -- like ReadBufferExtended, but doesn't require
  *		a relcache entry for the relation.
- *
- * NB: At present, this function may only be used on permanent relations, which
- * is OK, because we only use it during XLOG replay.  If in the future we
- * want to use it on temporary or unlogged relations, we could pass additional
- * parameters.
  */
 Buffer
 ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,
 						  BlockNumber blockNum, ReadBufferMode mode,
-						  BufferAccessStrategy strategy)
+						  BufferAccessStrategy strategy, char relpersistence)
 {
 	bool		hit;
 
 	SMgrRelation smgr = smgropen(rnode, InvalidBackendId);
 
-	Assert(InRecovery);
-
-	return ReadBuffer_common(smgr, RELPERSISTENCE_PERMANENT, forkNum, blockNum,
+	return ReadBuffer_common(smgr, relpersistence, forkNum, blockNum,
 							 mode, strategy, &hit);
 }
 
@@ -797,7 +790,7 @@ ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,
  *
  * *hit is set to true if the request was satisfied from shared buffer cache.
  */
-static Buffer
+Buffer
 ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
 				  BlockNumber blockNum, ReadBufferMode mode,
 				  BufferAccessStrategy strategy, bool *hit)
@@ -3402,10 +3395,13 @@ FindAndDropRelFileNodeBuffers(RelFileNode rnode, ForkNumber forkNum,
  *		database, to avoid trying to flush data to disk when the directory
  *		tree no longer exists.  Implementation is pretty similar to
  *		DropRelFileNodeBuffers() which is for destroying just one relation.
+ *
+ *		If a valid tablespace oid is passed then it will compare the tablespace
+ *		oid as well otherwise just the db oid.
  * --------------------------------------------------------------------
  */
 void
-DropDatabaseBuffers(Oid dbid)
+DropDatabaseBuffers(Oid dbid, Oid tbsid)
 {
 	int			i;
 
@@ -3423,11 +3419,13 @@ DropDatabaseBuffers(Oid dbid)
 		 * As in DropRelFileNodeBuffers, an unlocked precheck should be safe
 		 * and saves some cycles.
 		 */
-		if (bufHdr->tag.rnode.dbNode != dbid)
+		if (bufHdr->tag.rnode.dbNode != dbid ||
+			(OidIsValid(tbsid) && bufHdr->tag.rnode.spcNode != tbsid))
 			continue;
 
 		buf_state = LockBufHdr(bufHdr);
-		if (bufHdr->tag.rnode.dbNode == dbid)
+		if (bufHdr->tag.rnode.dbNode == dbid &&
+			(!OidIsValid(tbsid) || bufHdr->tag.rnode.spcNode == tbsid))
 			InvalidateBuffer(bufHdr);	/* releases spinlock */
 		else
 			UnlockBufHdr(bufHdr, buf_state);
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index cfce23ecbc..237c6a9078 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -184,7 +184,8 @@ extern Buffer ReadBufferExtended(Relation reln, ForkNumber forkNum,
 								 BufferAccessStrategy strategy);
 extern Buffer ReadBufferWithoutRelcache(RelFileNode rnode,
 										ForkNumber forkNum, BlockNumber blockNum,
-										ReadBufferMode mode, BufferAccessStrategy strategy);
+										ReadBufferMode mode, BufferAccessStrategy strategy,
+										char relpersistence);
 extern void ReleaseBuffer(Buffer buffer);
 extern void UnlockReleaseBuffer(Buffer buffer);
 extern void MarkBufferDirty(Buffer buffer);
@@ -207,7 +208,7 @@ extern void FlushDatabaseBuffers(Oid dbid);
 extern void DropRelFileNodeBuffers(struct SMgrRelationData *smgr_reln, ForkNumber *forkNum,
 								   int nforks, BlockNumber *firstDelBlock);
 extern void DropRelFileNodesAllBuffers(struct SMgrRelationData **smgr_reln, int nnodes);
-extern void DropDatabaseBuffers(Oid dbid);
+extern void DropDatabaseBuffers(Oid dbid, Oid tbsid);
 
 #define RelationGetNumberOfBlocks(reln) \
 	RelationGetNumberOfBlocksInFork(reln, MAIN_FORKNUM)
-- 
2.23.0