Clean up smgr.c/md.c APIs as per discussion a couple months ago. Instead of

having md.c return a success/failure boolean to smgr.c, which was just going
to elog anyway, let md.c issue the elog messages itself.  This allows better
error reporting, particularly in cases such as "short read" or "short write"
which Peter was complaining of.  Also, remove the kluge of allowing mdread()
to return zeroes from a read-beyond-EOF: this is now an error condition
except when InRecovery or zero_damaged_pages = true.  (Hash indexes used to
require that behavior, but no more.)  Also, enforce that mdwrite() is to be
used for rewriting existing blocks while mdextend() is to be used for
extending the relation EOF.  This restriction lets us get rid of the old
ad-hoc defense against creating huge files by an accidental reference to
a bogus block number: we'll only create new segments in mdextend() not
mdwrite() or mdread().  (Again, when InRecovery we allow it anyway, since
we need to allow updates of blocks that were later truncated away.)
Also, clean up the original makeshift patch for bug #2737: move the
responsibility for padding relation segments to full length into md.c.

1 files changed, 12 insertions, 13 deletions

diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h
index b768a5b530..1c8963ec21 100644
--- a/src/include/storage/smgr.h
+++ b/src/include/storage/smgr.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/smgr.h,v 1.55 2006/03/24 04:32:13 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/storage/smgr.h,v 1.56 2007/01/03 18:11:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -72,7 +72,7 @@ extern void smgrread(SMgrRelation reln, BlockNumber blocknum, char *buffer);
 extern void smgrwrite(SMgrRelation reln, BlockNumber blocknum, char *buffer,
 		  bool isTemp);
 extern BlockNumber smgrnblocks(SMgrRelation reln);
-extern BlockNumber smgrtruncate(SMgrRelation reln, BlockNumber nblocks,
+extern void smgrtruncate(SMgrRelation reln, BlockNumber nblocks,
 			 bool isTemp);
 extern void smgrimmedsync(SMgrRelation reln);
 extern void smgrDoPendingDeletes(bool isCommit);
@@ -91,20 +91,19 @@ extern void smgr_desc(StringInfo buf, uint8 xl_info, char *rec);
 /* internals: move me elsewhere -- ay 7/94 */
 
 /* in md.c */
-extern bool mdinit(void);
-extern bool mdclose(SMgrRelation reln);
-extern bool mdcreate(SMgrRelation reln, bool isRedo);
-extern bool mdunlink(RelFileNode rnode, bool isRedo);
-extern bool mdextend(SMgrRelation reln, BlockNumber blocknum, char *buffer,
+extern void mdinit(void);
+extern void mdclose(SMgrRelation reln);
+extern void mdcreate(SMgrRelation reln, bool isRedo);
+extern void mdunlink(RelFileNode rnode, bool isRedo);
+extern void mdextend(SMgrRelation reln, BlockNumber blocknum, char *buffer,
 		 bool isTemp);
-extern bool mdread(SMgrRelation reln, BlockNumber blocknum, char *buffer);
-extern bool mdwrite(SMgrRelation reln, BlockNumber blocknum, char *buffer,
+extern void mdread(SMgrRelation reln, BlockNumber blocknum, char *buffer);
+extern void mdwrite(SMgrRelation reln, BlockNumber blocknum, char *buffer,
 		bool isTemp);
 extern BlockNumber mdnblocks(SMgrRelation reln);
-extern BlockNumber mdtruncate(SMgrRelation reln, BlockNumber nblocks,
-		   bool isTemp);
-extern bool mdimmedsync(SMgrRelation reln);
-extern bool mdsync(void);
+extern void mdtruncate(SMgrRelation reln, BlockNumber nblocks, bool isTemp);
+extern void mdimmedsync(SMgrRelation reln);
+extern void mdsync(void);
 
 extern void RememberFsyncRequest(RelFileNode rnode, BlockNumber segno);