btrfs: move leak debug code to functions

Clean up the leak debugging in extent_io.c by moving
the debug code into functions.  This also removes the
list_heads used for debugging from the extent_buffer
and extent_state structures when debug is not enabled.

Since we need a global debug config to do that last
part, implement CONFIG_BTRFS_DEBUG to accommodate.

Thanks to Dave Sterba for the Kconfig bit.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

3 files changed, 72 insertions, 56 deletions

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 0f5374c9e368..2b3b83296977 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -63,3 +63,12 @@ config BTRFS_FS_RUN_SANITY_TESTS
 
           If unsure, say N.
 
+config BTRFS_DEBUG
+        bool "Btrfs debugging support"
+        depends on BTRFS_FS
+        help
+          Enable run-time debugging support for the btrfs filesystem. This may
+          enable additional and expensive checks with negative impact on
+          performance, or export extra information via sysfs.
+
+          If unsure, say N.
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d9a82f261e04..f110d12de2d5 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -24,12 +24,62 @@
 static struct kmem_cache *extent_state_cache;
 static struct kmem_cache *extent_buffer_cache;
 
+#ifdef CONFIG_BTRFS_DEBUG
 static LIST_HEAD(buffers);
 static LIST_HEAD(states);
 
-#define LEAK_DEBUG 0
-#if LEAK_DEBUG
 static DEFINE_SPINLOCK(leak_lock);
+
+static inline
+void btrfs_leak_debug_add(struct list_head *new, struct list_head *head)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&leak_lock, flags);
+        list_add(new, head);
+        spin_unlock_irqrestore(&leak_lock, flags);
+}
+
+static inline
+void btrfs_leak_debug_del(struct list_head *entry)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&leak_lock, flags);
+        list_del(entry);
+        spin_unlock_irqrestore(&leak_lock, flags);
+}
+
+static inline
+void btrfs_leak_debug_check(void)
+{
+        struct extent_state *state;
+        struct extent_buffer *eb;
+
+        while (!list_empty(&states)) {
+                state = list_entry(states.next, struct extent_state, leak_list);
+                printk(KERN_ERR "btrfs state leak: start %llu end %llu "
+                       "state %lu in tree %p refs %d\n",
+                       (unsigned long long)state->start,
+                       (unsigned long long)state->end,
+                       state->state, state->tree, atomic_read(&state->refs));
+                list_del(&state->leak_list);
+                kmem_cache_free(extent_state_cache, state);
+        }
+
+        while (!list_empty(&buffers)) {
+                eb = list_entry(buffers.next, struct extent_buffer, leak_list);
+                printk(KERN_ERR "btrfs buffer leak start %llu len %lu "
+                       "refs %d\n", (unsigned long long)eb->start,
+                       eb->len, atomic_read(&eb->refs));
+                list_del(&eb->leak_list);
+                kmem_cache_free(extent_buffer_cache, eb);
+        }
+}
+#else
+#define btrfs_leak_debug_add(new, head) do {} while (0)
+#define btrfs_leak_debug_del(entry)     do {} while (0)
+#define btrfs_leak_debug_check()        do {} while (0)
 #endif
 
 #define BUFFER_LRU_MAX 64
@@ -84,29 +134,7 @@ free_state_cache:
 
 void extent_io_exit(void)
 {
-        struct extent_state *state;
-        struct extent_buffer *eb;
-
-        while (!list_empty(&states)) {
-                state = list_entry(states.next, struct extent_state, leak_list);
-                printk(KERN_ERR "btrfs state leak: start %llu end %llu "
-                       "state %lu in tree %p refs %d\n",
-                       (unsigned long long)state->start,
-                       (unsigned long long)state->end,
-                       state->state, state->tree, atomic_read(&state->refs));
-                list_del(&state->leak_list);
-                kmem_cache_free(extent_state_cache, state);
-
-        }
-
-        while (!list_empty(&buffers)) {
-                eb = list_entry(buffers.next, struct extent_buffer, leak_list);
-                printk(KERN_ERR "btrfs buffer leak start %llu len %lu "
-                       "refs %d\n", (unsigned long long)eb->start,
-                       eb->len, atomic_read(&eb->refs));
-                list_del(&eb->leak_list);
-                kmem_cache_free(extent_buffer_cache, eb);
-        }
+        btrfs_leak_debug_check();
 
         /*
          * Make sure all delayed rcu free are flushed before we
@@ -134,9 +162,6 @@ void extent_io_tree_init(struct extent_io_tree *tree,
 static struct extent_state *alloc_extent_state(gfp_t mask)
 {
         struct extent_state *state;
-#if LEAK_DEBUG
-        unsigned long flags;
-#endif
 
         state = kmem_cache_alloc(extent_state_cache, mask);
         if (!state)
@@ -144,11 +169,7 @@ static struct extent_state *alloc_extent_state(gfp_t mask)
         state->state = 0;
         state->private = 0;
         state->tree = NULL;
-#if LEAK_DEBUG
-        spin_lock_irqsave(&leak_lock, flags);
-        list_add(&state->leak_list, &states);
-        spin_unlock_irqrestore(&leak_lock, flags);
-#endif
+        btrfs_leak_debug_add(&state->leak_list, &states);
         atomic_set(&state->refs, 1);
         init_waitqueue_head(&state->wq);
         trace_alloc_extent_state(state, mask, _RET_IP_);
@@ -160,15 +181,8 @@ void free_extent_state(struct extent_state *state)
         if (!state)
                 return;
         if (atomic_dec_and_test(&state->refs)) {
-#if LEAK_DEBUG
-                unsigned long flags;
-#endif
                 WARN_ON(state->tree);
-#if LEAK_DEBUG
-                spin_lock_irqsave(&leak_lock, flags);
-                list_del(&state->leak_list);
-                spin_unlock_irqrestore(&leak_lock, flags);
-#endif
+                btrfs_leak_debug_del(&state->leak_list);
                 trace_free_extent_state(state, _RET_IP_);
                 kmem_cache_free(extent_state_cache, state);
         }
@@ -4065,12 +4079,7 @@ out:
 
 static void __free_extent_buffer(struct extent_buffer *eb)
 {
-#if LEAK_DEBUG
-        unsigned long flags;
-        spin_lock_irqsave(&leak_lock, flags);
-        list_del(&eb->leak_list);
-        spin_unlock_irqrestore(&leak_lock, flags);
-#endif
+        btrfs_leak_debug_del(&eb->leak_list);
         kmem_cache_free(extent_buffer_cache, eb);
 }
 
@@ -4080,9 +4089,6 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
                                                    gfp_t mask)
 {
         struct extent_buffer *eb = NULL;
-#if LEAK_DEBUG
-        unsigned long flags;
-#endif
 
         eb = kmem_cache_zalloc(extent_buffer_cache, mask);
         if (eb == NULL)
@@ -4102,11 +4108,8 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
         init_waitqueue_head(&eb->write_lock_wq);
         init_waitqueue_head(&eb->read_lock_wq);
 
-#if LEAK_DEBUG
-        spin_lock_irqsave(&leak_lock, flags);
-        list_add(&eb->leak_list, &buffers);
-        spin_unlock_irqrestore(&leak_lock, flags);
-#endif
+        btrfs_leak_debug_add(&eb->leak_list, &buffers);
+
         spin_lock_init(&eb->refs_lock);
         atomic_set(&eb->refs, 1);
         atomic_set(&eb->io_pages, 0);
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index fa86861de244..59d883bc3ed3 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -116,7 +116,9 @@ struct extent_state {
         /* for use by the FS */
         u64 private;
 
+#ifdef CONFIG_BTRFS_DEBUG
         struct list_head leak_list;
+#endif
 };
 
 #define INLINE_EXTENT_BUFFER_PAGES 16
@@ -132,7 +134,6 @@ struct extent_buffer {
         atomic_t refs;
         atomic_t io_pages;
         int read_mirror;
-        struct list_head leak_list;
         struct rcu_head rcu_head;
         pid_t lock_owner;
 
@@ -159,6 +160,9 @@ struct extent_buffer {
         wait_queue_head_t read_lock_wq;
         wait_queue_head_t lock_wq;
         struct page *pages[INLINE_EXTENT_BUFFER_PAGES];
+#ifdef CONFIG_BTRFS_DEBUG
+        struct list_head leak_list;
+#endif
 };
 
 static inline void extent_set_compress_type(unsigned long *bio_flags,