xfs: introduce CONFIG_XFS_WARN

Running a CONFIG_XFS_DEBUG kernel in production environments is not
the best idea as it introduces significant overhead, can change
the behaviour of algorithms (such as allocation) to improve test
coverage, and (most importantly) panic the machine on non-fatal
errors.

There are many cases where all we want to do is run a
kernel with more bounds checking enabled, such as is provided by the
ASSERT() statements throughout the code, but without all the
potential overhead and drawbacks.

This patch converts all the ASSERT statements to evaluate as
WARN_ON(1) statements and hence if they fail dump a warning and a
stack trace to the log. This has minimal overhead and does not
change any algorithms, and will allow us to find strange "out of
bounds" problems more easily on production machines.

There are a few places where assert statements contain debug only
code. These are converted to be debug-or-warn only code so that we
still get all the assert checks in the code.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

13 files changed, 63 insertions, 24 deletions

diff --git a/fs/xfs/Kconfig b/fs/xfs/Kconfig
index cc33aaf219f..399e8cec6e6 100644
--- a/fs/xfs/Kconfig
+++ b/fs/xfs/Kconfig
@@ -69,6 +69,19 @@ config XFS_RT
 
 	  If unsure, say N.
 
+config XFS_WARN
+	bool "XFS Verbose Warnings"
+	depends on XFS_FS && !XFS_DEBUG
+	help
+	  Say Y here to get an XFS build with many additional warnings.
+	  It converts ASSERT checks to WARN, so will log any out-of-bounds
+	  conditions that occur that would otherwise be missed. It is much
+	  lighter weight than XFS_DEBUG and does not modify algorithms and will
+	  not cause the kernel to panic on non-fatal errors.
+
+	  However, similar to XFS_DEBUG, it is only advisable to use this if you
+	  are debugging a particular problem.
+
 config XFS_DEBUG
 	bool "XFS Debugging support"
 	depends on XFS_FS
diff --git a/fs/xfs/mrlock.h b/fs/xfs/mrlock.h
index ff6a19873e5..e3c92d19e54 100644
--- a/fs/xfs/mrlock.h
+++ b/fs/xfs/mrlock.h
@@ -22,12 +22,12 @@
 
 typedef struct {
 	struct rw_semaphore	mr_lock;
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	int			mr_writer;
 #endif
 } mrlock_t;
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 #define mrinit(mrp, name)	\
 	do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
 #else
@@ -46,7 +46,7 @@ static inline void mraccess_nested(mrlock_t *mrp, int subclass)
 static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
 {
 	down_write_nested(&mrp->mr_lock, subclass);
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	mrp->mr_writer = 1;
 #endif
 }
@@ -60,7 +60,7 @@ static inline int mrtryupdate(mrlock_t *mrp)
 {
 	if (!down_write_trylock(&mrp->mr_lock))
 		return 0;
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	mrp->mr_writer = 1;
 #endif
 	return 1;
@@ -68,7 +68,7 @@ static inline int mrtryupdate(mrlock_t *mrp)
 
 static inline void mrunlock_excl(mrlock_t *mrp)
 {
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	mrp->mr_writer = 0;
 #endif
 	up_write(&mrp->mr_lock);
@@ -81,7 +81,7 @@ static inline void mrunlock_shared(mrlock_t *mrp)
 
 static inline void mrdemote(mrlock_t *mrp)
 {
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	mrp->mr_writer = 0;
 #endif
 	downgrade_write(&mrp->mr_lock);
diff --git a/fs/xfs/xfs.h b/fs/xfs/xfs.h
index d8b11b7f94a..a742c47f7d5 100644
--- a/fs/xfs/xfs.h
+++ b/fs/xfs/xfs.h
@@ -24,6 +24,11 @@
 #define XFS_BUF_LOCK_TRACKING 1
 #endif
 
+#ifdef CONFIG_XFS_WARN
+#define XFS_WARN 1
+#endif
+
+
 #include "xfs_linux.h"
 
 #endif	/* __XFS_H__ */
diff --git a/fs/xfs/xfs_alloc_btree.c b/fs/xfs/xfs_alloc_btree.c
index 30c4c1434fa..cafc90251d1 100644
--- a/fs/xfs/xfs_alloc_btree.c
+++ b/fs/xfs/xfs_alloc_btree.c
@@ -386,7 +386,7 @@ const struct xfs_buf_ops xfs_allocbt_buf_ops = {
 };
 
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 STATIC int
 xfs_allocbt_keys_inorder(
 	struct xfs_btree_cur	*cur,
@@ -442,7 +442,7 @@ static const struct xfs_btree_ops xfs_allocbt_ops = {
 	.init_ptr_from_cur	= xfs_allocbt_init_ptr_from_cur,
 	.key_diff		= xfs_allocbt_key_diff,
 	.buf_ops		= &xfs_allocbt_buf_ops,
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	.keys_inorder		= xfs_allocbt_keys_inorder,
 	.recs_inorder		= xfs_allocbt_recs_inorder,
 #endif
diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c
index 3a86c3fa6de..0c61a22be6f 100644
--- a/fs/xfs/xfs_bmap_btree.c
+++ b/fs/xfs/xfs_bmap_btree.c
@@ -813,7 +813,7 @@ const struct xfs_buf_ops xfs_bmbt_buf_ops = {
 };
 
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 STATIC int
 xfs_bmbt_keys_inorder(
 	struct xfs_btree_cur	*cur,
@@ -853,7 +853,7 @@ static const struct xfs_btree_ops xfs_bmbt_ops = {
 	.init_ptr_from_cur	= xfs_bmbt_init_ptr_from_cur,
 	.key_diff		= xfs_bmbt_key_diff,
 	.buf_ops		= &xfs_bmbt_buf_ops,
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	.keys_inorder		= xfs_bmbt_keys_inorder,
 	.recs_inorder		= xfs_bmbt_recs_inorder,
 #endif
diff --git a/fs/xfs/xfs_btree.h b/fs/xfs/xfs_btree.h
index 6e6c915673f..55e3c7cc3c3 100644
--- a/fs/xfs/xfs_btree.h
+++ b/fs/xfs/xfs_btree.h
@@ -215,7 +215,7 @@ struct xfs_btree_ops {
 
 	const struct xfs_buf_ops	*buf_ops;
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	/* check that k1 is lower than k2 */
 	int	(*keys_inorder)(struct xfs_btree_cur *cur,
 				union xfs_btree_key *k1,
diff --git a/fs/xfs/xfs_dir2_node.c b/fs/xfs/xfs_dir2_node.c
index ecc6c661064..5246de4912d 100644
--- a/fs/xfs/xfs_dir2_node.c
+++ b/fs/xfs/xfs_dir2_node.c
@@ -993,7 +993,7 @@ xfs_dir2_leafn_rebalance(
 	xfs_dir2_leaf_t		*leaf1;		/* first leaf structure */
 	xfs_dir2_leaf_t		*leaf2;		/* second leaf structure */
 	int			mid;		/* midpoint leaf index */
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	int			oldstale;	/* old count of stale leaves */
 #endif
 	int			oldsum;		/* old total leaf count */
@@ -1022,7 +1022,7 @@ xfs_dir2_leafn_rebalance(
 	ents2 = xfs_dir3_leaf_ents_p(leaf2);
 
 	oldsum = hdr1.count + hdr2.count;
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	oldstale = hdr1.stale + hdr2.stale;
 #endif
 	mid = oldsum >> 1;
diff --git a/fs/xfs/xfs_ialloc_btree.c b/fs/xfs/xfs_ialloc_btree.c
index c82ac886742..5448eb6b8c1 100644
--- a/fs/xfs/xfs_ialloc_btree.c
+++ b/fs/xfs/xfs_ialloc_btree.c
@@ -272,7 +272,7 @@ const struct xfs_buf_ops xfs_inobt_buf_ops = {
 	.verify_write = xfs_inobt_write_verify,
 };
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 STATIC int
 xfs_inobt_keys_inorder(
 	struct xfs_btree_cur	*cur,
@@ -310,7 +310,7 @@ static const struct xfs_btree_ops xfs_inobt_ops = {
 	.init_ptr_from_cur	= xfs_inobt_init_ptr_from_cur,
 	.key_diff		= xfs_inobt_key_diff,
 	.buf_ops		= &xfs_inobt_buf_ops,
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	.keys_inorder		= xfs_inobt_keys_inorder,
 	.recs_inorder		= xfs_inobt_recs_inorder,
 #endif
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 558ef494720..efbe1accb6c 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -287,7 +287,7 @@ xfs_ilock_demote(
 	trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
 }
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 int
 xfs_isilocked(
 	xfs_inode_t		*ip,
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index 14e59d953b7..800f896a6cc 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -293,22 +293,34 @@ static inline __uint64_t howmany_64(__uint64_t x, __uint32_t y)
 #define ASSERT_ALWAYS(expr)	\
 	(unlikely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
 
-#ifndef DEBUG
-#define ASSERT(expr)	((void)0)
+#ifdef DEBUG
+#define ASSERT(expr)	\
+	(unlikely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
 
 #ifndef STATIC
-# define STATIC static noinline
+# define STATIC noinline
 #endif
 
-#else /* DEBUG */
+#else	/* !DEBUG */
+
+#ifdef XFS_WARN
 
 #define ASSERT(expr)	\
-	(unlikely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
+	(unlikely(expr) ? (void)0 : asswarn(#expr, __FILE__, __LINE__))
 
 #ifndef STATIC
-# define STATIC noinline
+# define STATIC static noinline
+#endif
+
+#else	/* !DEBUG && !XFS_WARN */
+
+#define ASSERT(expr)	((void)0)
+
+#ifndef STATIC
+# define STATIC static noinline
 #endif
 
+#endif /* XFS_WARN */
 #endif /* DEBUG */
 
 #endif /* __XFS_LINUX__ */
diff --git a/fs/xfs/xfs_message.c b/fs/xfs/xfs_message.c
index 331cd9f83a7..9163dc14053 100644
--- a/fs/xfs/xfs_message.c
+++ b/fs/xfs/xfs_message.c
@@ -93,6 +93,14 @@ xfs_alert_tag(
 }
 
 void
+asswarn(char *expr, char *file, int line)
+{
+	xfs_warn(NULL, "Assertion failed: %s, file: %s, line: %d",
+		expr, file, line);
+	WARN_ON(1);
+}
+
+void
 assfail(char *expr, char *file, int line)
 {
 	xfs_emerg(NULL, "Assertion failed: %s, file: %s, line: %d",
diff --git a/fs/xfs/xfs_message.h b/fs/xfs/xfs_message.h
index 76c81982f96..85401155750 100644
--- a/fs/xfs/xfs_message.h
+++ b/fs/xfs/xfs_message.h
@@ -57,6 +57,7 @@ do {									\
 	xfs_printk_ratelimited(xfs_debug, dev, fmt, ##__VA_ARGS__)
 
 extern void assfail(char *expr, char *f, int l);
+extern void asswarn(char *expr, char *f, int l);
 
 extern void xfs_hex_dump(void *p, int length);
 
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index cd29f617102..a44dba5b2cd 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -405,7 +405,7 @@ typedef struct xfs_trans {
 	int64_t			t_res_fdblocks_delta; /* on-disk only chg */
 	int64_t			t_frextents_delta;/* superblock freextents chg*/
 	int64_t			t_res_frextents_delta; /* on-disk only chg */
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 	int64_t			t_ag_freeblks_delta; /* debugging counter */
 	int64_t			t_ag_flist_delta; /* debugging counter */
 	int64_t			t_ag_btree_delta; /* debugging counter */
@@ -433,7 +433,7 @@ typedef struct xfs_trans {
 #define	xfs_trans_get_block_res(tp)	((tp)->t_blk_res)
 #define	xfs_trans_set_sync(tp)		((tp)->t_flags |= XFS_TRANS_SYNC)
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(XFS_WARN)
 #define	xfs_trans_agblocks_delta(tp, d)	((tp)->t_ag_freeblks_delta += (int64_t)d)
 #define	xfs_trans_agflist_delta(tp, d)	((tp)->t_ag_flist_delta += (int64_t)d)
 #define	xfs_trans_agbtree_delta(tp, d)	((tp)->t_ag_btree_delta += (int64_t)d)