reduce FSync option to a boolean

there is no use for Thorough mode any more, so simplify the
configuration.

src/config.c

@@ -38,7 +38,7 @@ channel_conf_t global_conf;
 store_conf_t *stores;
 channel_conf_t *channels;
 group_conf_t *groups;
-int FSyncLevel = FSYNC_NORMAL;
+int UseFSync = 1;
 
 #define ARG_OPTIONAL 0
 #define ARG_REQUIRED 1
@@ -470,13 +470,7 @@ load_config( const char *where, int pseudo )
 		}
 		else if (!strcasecmp( "FSync", cfile.cmd ))
 		{
-			arg = cfile.val;
+			UseFSync = parse_bool( &cfile );
-			if (!strcasecmp( "None", arg ))
-				FSyncLevel = FSYNC_NONE;
-			else if (!strcasecmp( "Normal", arg ))
-				FSyncLevel = FSYNC_NORMAL;
-			else if (!strcasecmp( "Thorough", arg ))
-				FSyncLevel = FSYNC_THOROUGH;
 		}
 		else if (!getopt_helper( &cfile, &gcops, &global_conf ))
 		{

src/drv_maildir.c

@@ -439,7 +439,7 @@ maildir_store_uid( maildir_store_t *ctx )
 
 	n = sprintf( buf, "%d\n%d\n", ctx->gen.uidvalidity, ctx->nuid );
 	lseek( ctx->uvfd, 0, SEEK_SET );
-	if (write( ctx->uvfd, buf, n ) != n || ftruncate( ctx->uvfd, n ) || (FSyncLevel >= FSYNC_NORMAL && fdatasync( ctx->uvfd ))) {
+	if (write( ctx->uvfd, buf, n ) != n || ftruncate( ctx->uvfd, n ) || (UseFSync && fdatasync( ctx->uvfd ))) {
 		error( "Maildir error: cannot write UIDVALIDITY.\n" );
 		return DRV_BOX_BAD;
 	}
@@ -1213,7 +1213,7 @@ maildir_store_msg( store_t *gctx, msg_data_t *data, int to_trash,
 	}
 	ret = write( fd, data->data, data->len );
 	free( data->data );
-	if (ret != data->len || ((FSyncLevel >= FSYNC_NORMAL) && (ret = fsync( fd )))) {
+	if (ret != data->len || (UseFSync && (ret = fsync( fd )))) {
 		if (ret < 0)
 			sys_error( "Maildir error: cannot write %s", buf );
 		else

src/isync.h

@@ -488,12 +488,7 @@ extern driver_t *drivers[N_DRIVERS];
 extern channel_conf_t global_conf;
 extern channel_conf_t *channels;
 extern group_conf_t *groups;
-
+extern int UseFSync;
-#define FSYNC_NONE     0
-#define FSYNC_NORMAL   1
-#define FSYNC_THOROUGH 2
-
-extern int FSyncLevel;
 
 int parse_bool( conffile_t *cfile );
 int parse_int( conffile_t *cfile );

src/mbsync.1

@@ -534,23 +534,16 @@ times within a Group.
 ..
 .SS Global Options
 .TP
-\fBFSync\fR {\fINone\fR|\fINormal\fR|\fIThorough\fR}
+\fBFSync\fR \fIyes\fR|\fIno\fR
-.br
+.br
-Select the amount of forced flushing \fBmbsync\fR performs, which determines
+Selects whether \fBmbsync\fR performs forced flushing, which determines
-the level of data safety after system crashes and power outages:
+the level of data safety after system crashes and power outages.
-.br
+Disabling it is reasonably safe for file systems which are mounted with
-\fBNone\fR - no flushing at all. This is reasonably safe for file systems
+data=ordered mode.
-which are mounted with data=ordered mode.
+Enabling it is a wise choice for file systems mounted with data=writeback,
-.br
+in particular modern systems like ext4, btrfs and xfs. The performance impact
-\fBNormal\fR - message and critical metadata writes are flushed. No data
+on older file systems may be disproportionate.
-should be lost due to crashes, though it is still possible that messages
+(Default: \fIyes\fR)
-are duplicated after crashes. This is the default, and is a wise choice for
-file systems mounted with data=writeback, in particular modern systems like
-ext4, btrfs and xfs. The performance impact on older file systems may be
-disproportionate.
-.br
-\fBThorough\fR - this avoids message duplication after crashes as well,
-at some additional performance cost.
 ..
 .SH INHERENT PROBLEMS
 Changes done after \fBmbsync\fR has retrieved the message list will not be

src/run-tests.pl

@@ -249,7 +249,7 @@ sub writecfg($$$)
 	open(FILE, ">", ".mbsyncrc") or
 		die "Cannot open .mbsyncrc.\n";
 	print FILE
-"FSync None
+"FSync no
 
 MaildirStore master
 Path ./

src/sync.c

@@ -44,7 +44,7 @@ const char *str_ms[] = { "master", "slave" }, *str_hl[] = { "push", "pull" };
 void
 Fclose( FILE *f, int safe )
 {
-	if ((safe && (fflush( f ) || (FSyncLevel >= FSYNC_NORMAL && fdatasync( fileno( f ) )))) || fclose( f ) == EOF) {
+	if ((safe && (fflush( f ) || (UseFSync && fdatasync( fileno( f ) )))) || fclose( f ) == EOF) {
 		sys_error( "Error: cannot close file. Disk full?" );
 		exit( 1 );
 	}
@@ -1511,7 +1511,7 @@ box_loaded( int sts, void *aux )
 	}
 
 	debug( "propagating new messages\n" );
-	if (FSyncLevel >= FSYNC_NORMAL)
+	if (UseFSync)
 		fdatasync( fileno( svars->jfp ) );
 	for (t = 0; t < 2; t++) {
 		Fprintf( svars->jfp, "%c %d\n", "{}"[t], svars->ctx[t]->uidnext );