btrfs: add debug check for extent_io range alignment

The 'end' value must exactly cover the end of the interval, which means
one byte less than the expected block alignment, or in case of a file
smaller than one block, one byte less than the inode size.
Signed-off-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

fs/btrfs/extent_io.c

@@ -77,10 +77,29 @@ void btrfs_leak_debug_check(void)
 		kmem_cache_free(extent_buffer_cache, eb);
 	}
 }
+
+#define btrfs_debug_check_extent_io_range(inode, start, end)		\
+	__btrfs_debug_check_extent_io_range(__func__, (inode), (start), (end))
+static inline void __btrfs_debug_check_extent_io_range(const char *caller,
+		struct inode *inode, u64 start, u64 end)
+{
+	u64 isize = i_size_read(inode);
+
+	if (end >= PAGE_SIZE && (end % 2) == 0 && end != isize - 1) {
+		printk_ratelimited(KERN_DEBUG
+		    "btrfs: %s: ino %llu isize %llu odd range [%llu,%llu]\n",
+				caller,
+				(unsigned long long)btrfs_ino(inode),
+				(unsigned long long)isize,
+				(unsigned long long)start,
+				(unsigned long long)end);
+	}
+}
 #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)
+#define btrfs_debug_check_extent_io_range(c, s, e)	do {} while (0)
 #endif
 
 #define BUFFER_LRU_MAX 64
@@ -522,6 +541,8 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	int err;
 	int clear = 0;
 
+	btrfs_debug_check_extent_io_range(tree->mapping->host, start, end);
+
 	if (delete)
 		bits |= ~EXTENT_CTLBITS;
 	bits |= EXTENT_FIRST_DELALLOC;
@@ -677,6 +698,8 @@ static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	struct extent_state *state;
 	struct rb_node *node;
 
+	btrfs_debug_check_extent_io_range(tree->mapping->host, start, end);
+
 	spin_lock(&tree->lock);
 again:
 	while (1) {
@@ -769,6 +792,8 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	u64 last_start;
 	u64 last_end;
 
+	btrfs_debug_check_extent_io_range(tree->mapping->host, start, end);
+
 	bits |= EXTENT_FIRST_DELALLOC;
 again:
 	if (!prealloc && (mask & __GFP_WAIT)) {
@@ -989,6 +1014,8 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	u64 last_start;
 	u64 last_end;
 
+	btrfs_debug_check_extent_io_range(tree->mapping->host, start, end);
+
 again:
 	if (!prealloc && (mask & __GFP_WAIT)) {
 		prealloc = alloc_extent_state(mask);