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 cc33aaf219f1..399e8cec6e60 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 ff6a19873e5c..e3c92d19e540 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 d8b11b7f94aa..a742c47f7d5a 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 30c4c1434faf..cafc90251d19 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 3a86c3fa6de1..0c61a22be6fd 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 6e6c915673fe..55e3c7cc3c3d 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 ecc6c661064c..5246de4912d4 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 c82ac8867421..5448eb6b8c12 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 558ef4947206..efbe1accb6ca 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 14e59d953b7b..800f896a6cc4 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 331cd9f83a7f..9163dc140532 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 76c81982f964..85401155750e 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 cd29f6171021..a44dba5b2cdb 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)