fat: Add fat_msg() function for preformated FAT messages

Add fat_msg() to replace not cosequent used printk() in fs/fat/*
New message format should be as fallow:
FAT-fs (sda1): some thing happened.
Signed-off-by: NAlexey Fisher <bug-track@fisher-privat.net>
Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

fs/fat/fat.h

@@ -331,6 +331,8 @@ __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
 	__fat_fs_error(sb, 1, fmt , ## args)
 #define fat_fs_error_ratelimit(sb, fmt, args...) \
 	__fat_fs_error(sb, __ratelimit(&MSDOS_SB(sb)->ratelimit), fmt , ## args)
+void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
+	__attribute__ ((format (printf, 3, 4))) __cold;
 extern int fat_clusters_flush(struct super_block *sb);
 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,

fs/fat/misc.c

@@ -44,6 +44,22 @@ void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
 }
 EXPORT_SYMBOL_GPL(__fat_fs_error);
 
+/**
+ * fat_msg() - print preformated FAT specific messages. Every thing what is
+ * not fat_fs_error() should be fat_msg().
+ */
+void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	printk("%sFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
+	va_end(args);
+}
+
 /* Flushes the number of free clusters on FAT32 */
 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
 int fat_clusters_flush(struct super_block *sb)