[CF 5454] v2 - Bug: mdunlinkfiletag unlinks mainfork seg.0 instead of indicated fork+segment

This branch was automatically generated by a robot using patches from an
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https://commitfest.postgresql.org/patch/5454

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/CAEze2WjfP95SL_Hsu7GzYXLnQyEsT49zOnNvbY_mBLCFiQra1g@mail.gmail.com
Author(s): Matthias van de Meent

Author: Commitfest Bot

src/backend/storage/smgr/md.c

@@ -137,8 +137,7 @@ static void mdunlinkfork(RelFileLocatorBackend rlocator, ForkNumber forknum,
 static MdfdVec *mdopenfork(SMgrRelation reln, ForkNumber forknum, int behavior);
 static void register_dirty_segment(SMgrRelation reln, ForkNumber forknum,
 								   MdfdVec *seg);
-static void register_unlink_segment(RelFileLocatorBackend rlocator, ForkNumber forknum,
-									BlockNumber segno);
+static void register_unlink_tombstone(RelFileLocatorBackend rlocator);
 static void register_forget_request(RelFileLocatorBackend rlocator, ForkNumber forknum,
 									BlockNumber segno);
 static void _fdvec_resize(SMgrRelation reln,
@@ -410,7 +409,7 @@ mdunlinkfork(RelFileLocatorBackend rlocator, ForkNumber forknum, bool isRedo)
 
 		/* Register request to unlink first segment later */
 		save_errno = errno;
-		register_unlink_segment(rlocator, forknum, 0 /* first seg */ );
+		register_unlink_tombstone(rlocator);
 		errno = save_errno;
 	}
 
@@ -1532,15 +1531,16 @@ register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
 }
 
 /*
- * register_unlink_segment() -- Schedule a file to be deleted after next checkpoint
+ * register_unlink_tombstone()
+ * 
+ * Schedule a file to be deleted after next checkpoint
  */
 static void
-register_unlink_segment(RelFileLocatorBackend rlocator, ForkNumber forknum,
-						BlockNumber segno)
+register_unlink_tombstone(RelFileLocatorBackend rlocator)
 {
 	FileTag		tag;
 
-	INIT_MD_FILETAG(tag, rlocator.locator, forknum, segno);
+	INIT_MD_FILETAG(tag, rlocator.locator, MAIN_FORKNUM, 0);
 
 	/* Should never be used with temp relations */
 	Assert(!RelFileLocatorBackendIsTemp(rlocator));
@@ -1933,6 +1933,9 @@ mdunlinkfiletag(const FileTag *ftag, char *path)
 {
 	RelPathStr	p;
 
+	/* We only unlink tombstone files through this mechanism */
+	Assert(ftag->forknum == MAIN_FORKNUM && ftag->segno == 0);
+
 	/* Compute the path. */
 	p = relpathperm(ftag->rlocator, MAIN_FORKNUM);
 	strlcpy(path, p.str, MAXPGPATH);