btrfs: add nesting tags to the locking helpers

We will need these when we switch to an rwsem, so plumb in the
infrastructure here to use later on.  I violate the 80 character limit
some here because it'll be cleaned up later.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 7c99bf112960f01291366084ff4f85283f9fe27f..71e3fa30082c888677162c4c2fc7a30ec7eb4944 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2875,7 +2875,8 @@ cow_done:
                        } else {
                                if (!btrfs_tree_read_lock_atomic(b)) {
                                        btrfs_set_path_blocking(p);
-                                       __btrfs_tree_read_lock(b, p->recurse);
+                                       __btrfs_tree_read_lock(b, BTRFS_NESTING_NORMAL,
+                                                              p->recurse);
                                }
                                p->locks[level] = BTRFS_READ_LOCK;
                        }
@@ -5453,7 +5454,9 @@ again:
                        }
                        if (!ret) {
                                btrfs_set_path_blocking(path);
-                               __btrfs_tree_read_lock(next, path->recurse);
+                               __btrfs_tree_read_lock(next,
+                                                      BTRFS_NESTING_NORMAL,
+                                                      path->recurse);
                        }
                        next_rw_lock = BTRFS_READ_LOCK;
                }
@@ -5488,7 +5491,9 @@ again:
                        ret = btrfs_try_tree_read_lock(next);
                        if (!ret) {
                                btrfs_set_path_blocking(path);
-                               __btrfs_tree_read_lock(next, path->recurse);
+                               __btrfs_tree_read_lock(next,
+                                                      BTRFS_NESTING_NORMAL,
+                                                      path->recurse);
                        }
                        next_rw_lock = BTRFS_READ_LOCK;
                }

diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 740a0cde57314e8104caf82e8142a56982bf223f..66e02ebdd340890affc90063b12dd687ad995a0a 100644 (file)
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -244,7 +244,8 @@ void btrfs_set_lock_blocking_write(struct extent_buffer *eb)
  *
  * The rwlock is held upon exit.
  */
-void __btrfs_tree_read_lock(struct extent_buffer *eb, bool recurse)
+void __btrfs_tree_read_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest,
+                           bool recurse)
 {
        u64 start_ns = 0;
 
@@ -282,7 +283,7 @@ again:
 
 void btrfs_tree_read_lock(struct extent_buffer *eb)
 {
-       __btrfs_tree_read_lock(eb, false);
+       __btrfs_tree_read_lock(eb, BTRFS_NESTING_NORMAL, false);
 }
 
 /*
@@ -415,7 +416,7 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
  *
  * The rwlock is held for write upon exit.
  */
-void btrfs_tree_lock(struct extent_buffer *eb)
+void __btrfs_tree_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest)
        __acquires(&eb->lock)
 {
        u64 start_ns = 0;
@@ -440,6 +441,11 @@ again:
        trace_btrfs_tree_lock(eb, start_ns);
 }
 
+void btrfs_tree_lock(struct extent_buffer *eb)
+{
+       __btrfs_tree_lock(eb, BTRFS_NESTING_NORMAL);
+}
+
 /*
  * Release the write lock, either blocking or spinning (ie. there's no need
  * for an explicit blocking unlock, like btrfs_tree_read_unlock_blocking).
@@ -565,7 +571,7 @@ struct extent_buffer *__btrfs_read_lock_root_node(struct btrfs_root *root,
 
        while (1) {
                eb = btrfs_root_node(root);
-               __btrfs_tree_read_lock(eb, recurse);
+               __btrfs_tree_read_lock(eb, BTRFS_NESTING_NORMAL, recurse);
                if (eb == root->node)
                        break;
                btrfs_tree_read_unlock(eb);

diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index 31f6d6405c1de104fb656b0e9678f0185befc601..5fabda8f0a80f8ab766137f88715299ed0f32a41 100644 (file)
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -16,12 +16,35 @@
 #define BTRFS_WRITE_LOCK_BLOCKING 3
 #define BTRFS_READ_LOCK_BLOCKING 4
 
+/*
+ * We are limited in number of subclasses by MAX_LOCKDEP_SUBCLASSES, which at
+ * the time of this patch is 8, which is how many we use.  Keep this in mind if
+ * you decide you want to add another subclass.
+ */
+enum btrfs_lock_nesting {
+       BTRFS_NESTING_NORMAL,
+
+       /*
+        * We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so
+        * add this in here and add a static_assert to keep us from going over
+        * the limit.  As of this writing we're limited to 8, and we're
+        * definitely using 8, hence this check to keep us from messing up in
+        * the future.
+        */
+       BTRFS_NESTING_MAX,
+};
+
+static_assert(BTRFS_NESTING_MAX <= MAX_LOCKDEP_SUBCLASSES,
+             "too many lock subclasses defined");
+
 struct btrfs_path;
 
+void __btrfs_tree_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest);
 void btrfs_tree_lock(struct extent_buffer *eb);
 void btrfs_tree_unlock(struct extent_buffer *eb);
 
-void __btrfs_tree_read_lock(struct extent_buffer *eb, bool recurse);
+void __btrfs_tree_read_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest,
+                           bool recurse);
 void btrfs_tree_read_lock(struct extent_buffer *eb);
 void btrfs_tree_read_unlock(struct extent_buffer *eb);
 void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb);