fs: fat: extend get_fs_info() for write use

get_fs_info() was introduced in major re-work of read operation by Rob.
We want to reuse this function in write operation by extending it with
additional members in fsdata structure.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

fs/fat/fat.c

@@ -558,10 +558,17 @@ static int get_fs_info(fsdata *mydata)
 
 	if (mydata->fatsize == 32) {
 		mydata->fatlength = bs.fat32_length;
+		mydata->total_sect = bs.total_sect;
 	} else {
 		mydata->fatlength = bs.fat_length;
+		mydata->total_sect = (bs.sectors[1] << 8) + bs.sectors[0];
+		if (!mydata->total_sect)
+			mydata->total_sect = bs.total_sect;
 	}
+	if (!mydata->total_sect) /* unlikely */
+		mydata->total_sect = (u32)cur_part_info.size;
 
+	mydata->fats = bs.fats;
 	mydata->fat_sect = bs.reserved;
 
 	mydata->rootdir_sect = mydata->fat_sect + mydata->fatlength * bs.fats;

include/fat.h

@@ -173,6 +173,8 @@ typedef struct {
 	int	fatbufnum;	/* Used by get_fatent, init to -1 */
 	int	rootdir_size;	/* Size of root dir for non-FAT32 */
 	__u32	root_cluster;	/* First cluster of root dir for FAT32 */
+	u32	total_sect;	/* Number of sectors */
+	int	fats;		/* Number of FATs */
 } fsdata;
 
 static inline u32 clust_to_sect(fsdata *fsdata, u32 clust)