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>

1 files changed, 6 insertions, 6 deletions

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);