FAT: update the second FAT when writing a file

After susccessful write to the FAT partition,
fsck program may print warning message due to different FAT,
provided that the filesystem supports two FATs.

This patch makes the second FAT to be same with the first one
when writing a file.

Signed-off-by: Donggeun Kim <dg77.kim@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

fs/fat/fat_write.c

@@ -112,6 +112,7 @@ static void set_name(dir_entry *dirent, const char *filename)
 	debug("ext : %s\n", dirent->ext);
 }
 
+static __u8 num_of_fats;
 /*
  * Write fat buffer into block device
  */
@@ -134,6 +135,15 @@ static int flush_fat_buffer(fsdata *mydata)
 		return -1;
 	}
 
+	if (num_of_fats == 2) {
+		/* Update corresponding second FAT blocks */
+		startblock += mydata->fatlength;
+		if (disk_write(startblock, getsize, bufptr) < 0) {
+			debug("error: writing second FAT blocks\n");
+			return -1;
+		}
+	}
+
 	return 0;
 }
 
@@ -950,6 +960,7 @@ static int do_fat_write(const char *filename, void *buffer,
 
 	cursect = mydata->rootdir_sect
 		= mydata->fat_sect + mydata->fatlength * bs.fats;
+	num_of_fats = bs.fats;
 
 	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
 	mydata->clust_size = bs.cluster_size;