Simplify some ERROR paths clearing wait events and transient files

Transient files and wait events get normally cleaned up when seeing an
exception (be it in the context of a transaction for a backend or
another process like the checkpointer), hence there is little point in
complicating error code paths to do this work.  This shaves a bit of
code, and removes some extra handling with errno which needed to be
preserved during the cleanup steps done.

Reported-by: Masahiko Sawada
Author: Michael Paquier
Reviewed-by: Tom Lane, Masahiko Sawada
Discussion: https://postgr.es/m/CAD21AoDhHYVq5KkXfkaHhmjA-zJYj-e4teiRAJefvXuKJz1tKQ@mail.gmail.com

src/backend/access/transam/twophase.c

@@ -1693,26 +1693,18 @@ RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
 	pgstat_report_wait_start(WAIT_EVENT_TWOPHASE_FILE_WRITE);
 	if (write(fd, content, len) != len)
 	{
-		int			save_errno = errno;
-
-		pgstat_report_wait_end();
-		CloseTransientFile(fd);
-
 		/* if write didn't set errno, assume problem is no disk space */
-		errno = save_errno ? save_errno : ENOSPC;
+		if (errno == 0)
+			errno = ENOSPC;
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not write file \"%s\": %m", path)));
 	}
 	if (write(fd, &statefile_crc, sizeof(pg_crc32c)) != sizeof(pg_crc32c))
 	{
-		int			save_errno = errno;
-
-		pgstat_report_wait_end();
-		CloseTransientFile(fd);
-
 		/* if write didn't set errno, assume problem is no disk space */
-		errno = save_errno ? save_errno : ENOSPC;
+		if (errno == 0)
+			errno = ENOSPC;
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not write file \"%s\": %m", path)));
@@ -1725,15 +1717,9 @@ RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
 	 */
 	pgstat_report_wait_start(WAIT_EVENT_TWOPHASE_FILE_SYNC);
 	if (pg_fsync(fd) != 0)
-	{
-		int			save_errno = errno;
-
-		CloseTransientFile(fd);
-		errno = save_errno;
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not fsync file \"%s\": %m", path)));
-	}
 	pgstat_report_wait_end();
 
 	if (CloseTransientFile(fd) != 0)

src/backend/replication/logical/origin.c

@@ -579,12 +579,9 @@ CheckPointReplicationOrigin(void)
 	errno = 0;
 	if ((write(tmpfd, &magic, sizeof(magic))) != sizeof(magic))
 	{
-		int			save_errno = errno;
-
-		CloseTransientFile(tmpfd);
-
 		/* if write didn't set errno, assume problem is no disk space */
-		errno = save_errno ? save_errno : ENOSPC;
+		if (errno == 0)
+			errno = ENOSPC;
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not write to file \"%s\": %m",
@@ -624,12 +621,9 @@ CheckPointReplicationOrigin(void)
 		if ((write(tmpfd, &disk_state, sizeof(disk_state))) !=
 			sizeof(disk_state))
 		{
-			int			save_errno = errno;
-
-			CloseTransientFile(tmpfd);
-
 			/* if write didn't set errno, assume problem is no disk space */
-			errno = save_errno ? save_errno : ENOSPC;
+			if (errno == 0)
+				errno = ENOSPC;
 			ereport(PANIC,
 					(errcode_for_file_access(),
 					 errmsg("could not write to file \"%s\": %m",
@@ -646,12 +640,9 @@ CheckPointReplicationOrigin(void)
 	errno = 0;
 	if ((write(tmpfd, &crc, sizeof(crc))) != sizeof(crc))
 	{
-		int			save_errno = errno;
-
-		CloseTransientFile(tmpfd);
-
 		/* if write didn't set errno, assume problem is no disk space */
-		errno = save_errno ? save_errno : ENOSPC;
+		if (errno == 0)
+			errno = ENOSPC;
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not write to file \"%s\": %m",

src/backend/replication/slot.c

@@ -1398,16 +1398,10 @@ RestoreSlotFromDisk(const char *name)
 	 */
 	pgstat_report_wait_start(WAIT_EVENT_REPLICATION_SLOT_RESTORE_SYNC);
 	if (pg_fsync(fd) != 0)
-	{
-		int			save_errno = errno;
-
-		CloseTransientFile(fd);
-		errno = save_errno;
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not fsync file \"%s\": %m",
 						path)));
-	}
 	pgstat_report_wait_end();
 
 	/* Also sync the parent directory */
@@ -1421,10 +1415,6 @@ RestoreSlotFromDisk(const char *name)
 	pgstat_report_wait_end();
 	if (readBytes != ReplicationSlotOnDiskConstantSize)
 	{
-		int			saved_errno = errno;
-
-		CloseTransientFile(fd);
-		errno = saved_errno;
 		if (readBytes < 0)
 			ereport(PANIC,
 					(errcode_for_file_access(),
@@ -1466,10 +1456,6 @@ RestoreSlotFromDisk(const char *name)
 	pgstat_report_wait_end();
 	if (readBytes != cp.length)
 	{
-		int			saved_errno = errno;
-
-		CloseTransientFile(fd);
-		errno = saved_errno;
 		if (readBytes < 0)
 			ereport(PANIC,
 					(errcode_for_file_access(),

src/backend/storage/file/copydir.c

@@ -199,7 +199,6 @@ copy_file(char *fromfile, char *tofile)
 		pgstat_report_wait_start(WAIT_EVENT_COPY_FILE_WRITE);
 		if ((int) write(dstfd, buffer, nbytes) != nbytes)
 		{
-			pgstat_report_wait_end();
 			/* if write didn't set errno, assume problem is no disk space */
 			if (errno == 0)
 				errno = ENOSPC;