xfs: Add XFS messages to printk index

In order for end users to quickly react to new issues that come up in
production, it is proving useful to leverage the printk indexing system.

This printk index enables kernel developers to use calls to printk()
with changeable format strings (as they always have; no change of
expectations), while enabling end users to examine format strings to
detect changes.
Since end users are using regular expressions to match messages printed
through printk(), being able to detect changes in chosen format strings
from release to release provides a useful signal to review
printk()-matching regular expressions for any necessary updates.

So that detailed XFS messages are captures by this printk index, this
patch wraps the xfs_<level> and xfs_alert_tag functions.
Signed-off-by: Jonathan Lassoff <jof@thejof.com>
Reviewed-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_message.c

@@ -52,7 +52,7 @@ xfs_printk_level(
 }
 
 void
-xfs_alert_tag(
+_xfs_alert_tag(
 	const struct xfs_mount	*mp,
 	int			panic_tag,
 	const char		*fmt, ...)

fs/xfs/xfs_message.h

@@ -10,29 +10,40 @@ extern __printf(3, 4)
 void xfs_printk_level(const char *kern_level, const struct xfs_mount *mp,
 			const char *fmt, ...);
 
+#define xfs_printk_index_wrap(kern_level, mp, fmt, ...)		\
+({								\
+	printk_index_subsys_emit("%sXFS%s: ", kern_level, fmt);	\
+	xfs_printk_level(kern_level, mp, fmt, ##__VA_ARGS__);	\
+})
 #define xfs_emerg(mp, fmt, ...) \
-	xfs_printk_level(KERN_EMERG, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_EMERG, mp, fmt, ##__VA_ARGS__)
 #define xfs_alert(mp, fmt, ...) \
-	xfs_printk_level(KERN_ALERT, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_ALERT, mp, fmt, ##__VA_ARGS__)
 #define xfs_crit(mp, fmt, ...) \
-	xfs_printk_level(KERN_CRIT, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_CRIT, mp, fmt, ##__VA_ARGS__)
 #define xfs_err(mp, fmt, ...) \
-	xfs_printk_level(KERN_ERR, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_ERR, mp, fmt, ##__VA_ARGS__)
 #define xfs_warn(mp, fmt, ...) \
-	xfs_printk_level(KERN_WARNING, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_WARNING, mp, fmt, ##__VA_ARGS__)
 #define xfs_notice(mp, fmt, ...) \
-	xfs_printk_level(KERN_NOTICE, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_NOTICE, mp, fmt, ##__VA_ARGS__)
 #define xfs_info(mp, fmt, ...) \
-	xfs_printk_level(KERN_INFO, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_INFO, mp, fmt, ##__VA_ARGS__)
 #ifdef DEBUG
 #define xfs_debug(mp, fmt, ...) \
-	xfs_printk_level(KERN_DEBUG, mp, fmt, ##__VA_ARGS__)
+	xfs_printk_index_wrap(KERN_DEBUG, mp, fmt, ##__VA_ARGS__)
 #else
 #define xfs_debug(mp, fmt, ...) do {} while (0)
 #endif
 
+#define xfs_alert_tag(mp, tag, fmt, ...)			\
+({								\
+	printk_index_subsys_emit("%sXFS%s: ", KERN_ALERT, fmt);	\
+	_xfs_alert_tag(mp, tag, fmt, ##__VA_ARGS__);		\
+})
+
 extern __printf(3, 4)
-void xfs_alert_tag(const struct xfs_mount *mp, int tag, const char *fmt, ...);
+void _xfs_alert_tag(const struct xfs_mount *mp, int tag, const char *fmt, ...);
 
 #define xfs_printk_ratelimited(func, dev, fmt, ...)			\
 do {									\