Unite ReadBufferWithFork, ReadBufferWithStrategy, and ZeroOrReadBuffer

functions into one ReadBufferExtended function, that takes the strategy
and mode as argument. There's three modes, RBM_NORMAL which is the default
used by plain ReadBuffer(), RBM_ZERO, which replaces ZeroOrReadBuffer, and
a new mode RBM_ZERO_ON_ERROR, which allows callers to read corrupt pages
without throwing an error. The FSM needs the new mode to recover from
corrupt pages, which could happend if we crash after extending an FSM file,
and the new page is "torn".

Add fork number to some error messages in bufmgr.c, that still lacked it.

1 files changed, 14 insertions, 7 deletions

diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 72d4aec3979..56f584a78ba 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.115 2008/08/11 11:05:11 heikki Exp $
+ * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.116 2008/10/31 15:05:00 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -31,6 +31,14 @@ typedef enum BufferAccessStrategyType
 	BAS_VACUUM					/* VACUUM */
 } BufferAccessStrategyType;
 
+/* Possible modes for ReadBufferExtended() */
+typedef enum
+{
+	RBM_NORMAL,			/* Normal read */
+	RBM_ZERO,			/* Don't read from disk, caller will initialize */
+	RBM_ZERO_ON_ERROR	/* Read, but return an all-zeros page on error */
+} ReadBufferMode;
+
 /* in globals.c ... this duplicates miscadmin.h */
 extern PGDLLIMPORT int NBuffers;
 
@@ -144,13 +152,12 @@ extern PGDLLIMPORT int32 *LocalRefCount;
  * prototypes for functions in bufmgr.c
  */
 extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
-extern Buffer ReadBufferWithFork(Relation reln, ForkNumber forkNum, BlockNumber blockNum);
-extern Buffer ReadBufferWithStrategy(Relation reln, BlockNumber blockNum,
-					   BufferAccessStrategy strategy);
-extern Buffer ReadOrZeroBuffer(Relation reln, ForkNumber forkNum,
-							   BlockNumber blockNum);
+extern Buffer ReadBufferExtended(Relation reln, ForkNumber forkNum,
+								 BlockNumber blockNum, ReadBufferMode mode,
+								 BufferAccessStrategy strategy);
 extern Buffer ReadBufferWithoutRelcache(RelFileNode rnode, bool isTemp,
-					ForkNumber forkNum, BlockNumber blockNum, bool zeroPage);
+						ForkNumber forkNum, BlockNumber blockNum,
+						ReadBufferMode mode, BufferAccessStrategy strategy);
 extern void ReleaseBuffer(Buffer buffer);
 extern void UnlockReleaseBuffer(Buffer buffer);
 extern void MarkBufferDirty(Buffer buffer);