7 files changed, 99 insertions, 32 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index c8f4c540cc2c..42491d728e99 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -62,14 +62,38 @@ noinline void btrfs_set_path_blocking(struct btrfs_path *p)
 
 /*
  * reset all the locked nodes in the patch to spinning locks.
+ *
+ * held is used to keep lockdep happy, when lockdep is enabled
+ * we set held to a blocking lock before we go around and
+ * retake all the spinlocks in the path.  You can safely use NULL
+ * for held
  */
-noinline void btrfs_clear_path_blocking(struct btrfs_path *p)
+noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
+                                        struct extent_buffer *held)
 {
         int i;
-        for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /* lockdep really cares that we take all of these spinlocks
+         * in the right order.  If any of the locks in the path are not
+         * currently blocking, it is going to complain.  So, make really
+         * really sure by forcing the path to blocking before we clear
+         * the path blocking.
+         */
+        if (held)
+                btrfs_set_lock_blocking(held);
+        btrfs_set_path_blocking(p);
+#endif
+
+        for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
                 if (p->nodes[i] && p->locks[i])
                         btrfs_clear_lock_blocking(p->nodes[i]);
         }
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        if (held)
+                btrfs_clear_lock_blocking(held);
+#endif
 }
 
 /* this also releases the path */
@@ -279,7 +303,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                                                   trans->transid, level, &ins);
                 BUG_ON(ret);
                 cow = btrfs_init_new_buffer(trans, root, prealloc_dest,
-                                            buf->len);
+                                            buf->len, level);
         } else {
                 cow = btrfs_alloc_free_block(trans, root, buf->len,
                                              parent_start,
@@ -1559,7 +1583,7 @@ cow_done:
                 if (!p->skip_locking)
                         p->locks[level] = 1;
 
-                btrfs_clear_path_blocking(p);
+                btrfs_clear_path_blocking(p, NULL);
 
                 /*
                  * we have a lock on b and as long as we aren't changing
@@ -1598,7 +1622,7 @@ cow_done:
 
                                 btrfs_set_path_blocking(p);
                                 sret = split_node(trans, root, p, level);
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
 
                                 BUG_ON(sret > 0);
                                 if (sret) {
@@ -1618,7 +1642,7 @@ cow_done:
 
                                 btrfs_set_path_blocking(p);
                                 sret = balance_level(trans, root, p, level);
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
 
                                 if (sret) {
                                         ret = sret;
@@ -1681,13 +1705,13 @@ cow_done:
                         if (!p->skip_locking) {
                                 int lret;
 
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
                                 lret = btrfs_try_spin_lock(b);
 
                                 if (!lret) {
                                         btrfs_set_path_blocking(p);
                                         btrfs_tree_lock(b);
-                                        btrfs_clear_path_blocking(p);
+                                        btrfs_clear_path_blocking(p, b);
                                 }
                         }
                 } else {
@@ -1699,7 +1723,7 @@ cow_done:
                                 btrfs_set_path_blocking(p);
                                 sret = split_leaf(trans, root, key,
                                                       p, ins_len, ret == 0);
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
 
                                 BUG_ON(sret > 0);
                                 if (sret) {
@@ -3919,7 +3943,6 @@ find_next_key:
                                 btrfs_release_path(root, path);
                                 goto again;
                         } else {
-                                btrfs_clear_path_blocking(path);
                                 goto out;
                         }
                 }
@@ -3939,7 +3962,7 @@ find_next_key:
                 path->locks[level - 1] = 1;
                 path->nodes[level - 1] = cur;
                 unlock_up(path, level, 1);
-                btrfs_clear_path_blocking(path);
+                btrfs_clear_path_blocking(path, NULL);
         }
 out:
         if (ret == 0)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 3f7a8058df2b..766b31ae3186 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -43,11 +43,7 @@ struct btrfs_ordered_sum;
 
 #define BTRFS_ACL_NOT_CACHED    ((void *)-1)
 
-#ifdef CONFIG_LOCKDEP
-# define BTRFS_MAX_LEVEL 7
-#else
-# define BTRFS_MAX_LEVEL 8
-#endif
+#define BTRFS_MAX_LEVEL 8
 
 /* holds pointers to all of the tree roots */
 #define BTRFS_ROOT_TREE_OBJECTID 1ULL
@@ -1715,7 +1711,8 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                              u64 empty_size);
 struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
                                             struct btrfs_root *root,
-                                            u64 bytenr, u32 blocksize);
+                                            u64 bytenr, u32 blocksize,
+                                            int level);
 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
                        struct btrfs_root *root,
                        u64 num_bytes, u64 parent, u64 min_bytes,
@@ -1835,7 +1832,6 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p);
 struct btrfs_path *btrfs_alloc_path(void);
 void btrfs_free_path(struct btrfs_path *p);
 void btrfs_set_path_blocking(struct btrfs_path *p);
-void btrfs_clear_path_blocking(struct btrfs_path *p);
 void btrfs_unlock_up_safe(struct btrfs_path *p, int level);
 
 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5aebddd71193..adda739a0215 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -75,6 +75,40 @@ struct async_submit_bio {
         struct btrfs_work work;
 };
 
+/* These are used to set the lockdep class on the extent buffer locks.
+ * The class is set by the readpage_end_io_hook after the buffer has
+ * passed csum validation but before the pages are unlocked.
+ *
+ * The lockdep class is also set by btrfs_init_new_buffer on freshly
+ * allocated blocks.
+ *
+ * The class is based on the level in the tree block, which allows lockdep
+ * to know that lower nodes nest inside the locks of higher nodes.
+ *
+ * We also add a check to make sure the highest level of the tree is
+ * the same as our lockdep setup here.  If BTRFS_MAX_LEVEL changes, this
+ * code needs update as well.
+ */
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+# if BTRFS_MAX_LEVEL != 8
+#  error
+# endif
+static struct lock_class_key btrfs_eb_class[BTRFS_MAX_LEVEL + 1];
+static const char *btrfs_eb_name[BTRFS_MAX_LEVEL + 1] = {
+        /* leaf */
+        "btrfs-extent-00",
+        "btrfs-extent-01",
+        "btrfs-extent-02",
+        "btrfs-extent-03",
+        "btrfs-extent-04",
+        "btrfs-extent-05",
+        "btrfs-extent-06",
+        "btrfs-extent-07",
+        /* highest possible level */
+        "btrfs-extent-08",
+};
+#endif
+
 /*
  * extents on the btree inode are pretty simple, there's one extent
  * that covers the entire device
@@ -347,6 +381,15 @@ static int check_tree_block_fsid(struct btrfs_root *root,
         return ret;
 }
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void btrfs_set_buffer_lockdep_class(struct extent_buffer *eb, int level)
+{
+        lockdep_set_class_and_name(&eb->lock,
+                           &btrfs_eb_class[level],
+                           btrfs_eb_name[level]);
+}
+#endif
+
 static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
                                struct extent_state *state)
 {
@@ -392,6 +435,8 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
         }
         found_level = btrfs_header_level(eb);
 
+        btrfs_set_buffer_lockdep_class(eb, found_level);
+
         ret = csum_tree_block(root, eb, 1);
         if (ret)
                 ret = -EIO;
@@ -1777,7 +1822,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         ret = find_and_setup_root(tree_root, fs_info,
                                   BTRFS_DEV_TREE_OBJECTID, dev_root);
         dev_root->track_dirty = 1;
-
         if (ret)
                 goto fail_extent_root;
 
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 494a56eb2986..95029db227be 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -101,4 +101,14 @@ int btrfs_init_log_root_tree(struct btrfs_trans_handle *trans,
 int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
                        struct btrfs_root *root);
 int btree_lock_page_hook(struct page *page);
+
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void btrfs_set_buffer_lockdep_class(struct extent_buffer *eb, int level);
+#else
+static inline void btrfs_set_buffer_lockdep_class(struct extent_buffer *eb,
+                                                 int level)
+{
+}
+#endif
 #endif
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index c59e12036e20..cd86bffbdc9f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3416,7 +3416,8 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 
 struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
                                             struct btrfs_root *root,
-                                            u64 bytenr, u32 blocksize)
+                                            u64 bytenr, u32 blocksize,
+                                            int level)
 {
         struct extent_buffer *buf;
 
@@ -3424,6 +3425,7 @@ struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
         if (!buf)
                 return ERR_PTR(-ENOMEM);
         btrfs_set_header_generation(buf, trans->transid);
+        btrfs_set_buffer_lockdep_class(buf, level);
         btrfs_tree_lock(buf);
         clean_tree_block(trans, root, buf);
 
@@ -3467,7 +3469,8 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                 return ERR_PTR(ret);
         }
 
-        buf = btrfs_init_new_buffer(trans, root, ins.objectid, blocksize);
+        buf = btrfs_init_new_buffer(trans, root, ins.objectid,
+                                    blocksize, level);
         return buf;
 }
 
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 9ebe9385129b..85506c4a3af7 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -25,21 +25,10 @@
 #include "extent_io.h"
 #include "locking.h"
 
-/*
- * btrfs_header_level() isn't free, so don't call it when lockdep isn't
- * on
- */
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-static inline void spin_nested(struct extent_buffer *eb)
-{
-        spin_lock_nested(&eb->lock, BTRFS_MAX_LEVEL - btrfs_header_level(eb));
-}
-#else
 static inline void spin_nested(struct extent_buffer *eb)
 {
         spin_lock(&eb->lock);
 }
-#endif
 
 /*
  * Setting a lock to blocking will drop the spinlock and set the
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c793b6f50d8d..1316139bf9e8 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3102,6 +3102,8 @@ int btrfs_read_sys_array(struct btrfs_root *root)
         if (!sb)
                 return -ENOMEM;
         btrfs_set_buffer_uptodate(sb);
+        btrfs_set_buffer_lockdep_class(sb, 0);
+
         write_extent_buffer(sb, super_copy, 0, BTRFS_SUPER_INFO_SIZE);
         array_size = btrfs_super_sys_array_size(super_copy);