Btrfs: kill the pinned_mutex

This patch removes the pinned_mutex.  The extent io map has an internal tree
lock that protects the tree itself, and since we only copy the extent io map
when we are committing the transaction we don't need it there.  We also don't
need it when caching the block group since searching through the tree is also
protected by the internal map spin lock.

Signed-off-by: Josef Bacik <jbacik@redhat.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 5277445..aaa049b 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -728,7 +728,6 @@
 	struct mutex tree_log_mutex;
 	struct mutex transaction_kthread_mutex;
 	struct mutex cleaner_mutex;
-	struct mutex pinned_mutex;
 	struct mutex chunk_mutex;
 	struct mutex drop_mutex;
 	struct mutex volume_mutex;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1747dfd..ea59ebf 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1647,7 +1647,6 @@
 	mutex_init(&fs_info->ordered_operations_mutex);
 	mutex_init(&fs_info->tree_log_mutex);
 	mutex_init(&fs_info->drop_mutex);
-	mutex_init(&fs_info->pinned_mutex);
 	mutex_init(&fs_info->chunk_mutex);
 	mutex_init(&fs_info->transaction_kthread_mutex);
 	mutex_init(&fs_info->cleaner_mutex);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 6880a27..15d62a9 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -166,7 +166,6 @@
 	u64 extent_start, extent_end, size;
 	int ret;
 
-	mutex_lock(&info->pinned_mutex);
 	while (start < end) {
 		ret = find_first_extent_bit(&info->pinned_extents, start,
 					    &extent_start, &extent_end,
@@ -192,7 +191,6 @@
 		ret = btrfs_add_free_space(block_group, start, size);
 		BUG_ON(ret);
 	}
-	mutex_unlock(&info->pinned_mutex);
 
 	return 0;
 }
@@ -2047,7 +2045,6 @@
 	struct btrfs_block_group_cache *cache;
 	struct btrfs_fs_info *fs_info = root->fs_info;
 
-	WARN_ON(!mutex_is_locked(&root->fs_info->pinned_mutex));
 	if (pin) {
 		set_extent_dirty(&fs_info->pinned_extents,
 				bytenr, bytenr + num - 1, GFP_NOFS);
@@ -2055,7 +2052,6 @@
 		clear_extent_dirty(&fs_info->pinned_extents,
 				bytenr, bytenr + num - 1, GFP_NOFS);
 	}
-	mutex_unlock(&root->fs_info->pinned_mutex);
 
 	while (num > 0) {
 		cache = btrfs_lookup_block_group(fs_info, bytenr);
@@ -2127,7 +2123,6 @@
 	struct extent_io_tree *pinned_extents = &root->fs_info->pinned_extents;
 	int ret;
 
-	mutex_lock(&root->fs_info->pinned_mutex);
 	while (1) {
 		ret = find_first_extent_bit(pinned_extents, last,
 					    &start, &end, EXTENT_DIRTY);
@@ -2136,7 +2131,6 @@
 		set_extent_dirty(copy, start, end, GFP_NOFS);
 		last = end + 1;
 	}
-	mutex_unlock(&root->fs_info->pinned_mutex);
 	return 0;
 }
 
@@ -2149,7 +2143,6 @@
 	int ret;
 
 	while (1) {
-		mutex_lock(&root->fs_info->pinned_mutex);
 		ret = find_first_extent_bit(unpin, 0, &start, &end,
 					    EXTENT_DIRTY);
 		if (ret)
@@ -2163,7 +2156,6 @@
 
 		cond_resched();
 	}
-	mutex_unlock(&root->fs_info->pinned_mutex);
 	return ret;
 }
 
@@ -2205,7 +2197,6 @@
 	free_extent_buffer(buf);
 pinit:
 	btrfs_set_path_blocking(path);
-	mutex_lock(&root->fs_info->pinned_mutex);
 	/* unlocks the pinned mutex */
 	btrfs_update_pinned_extents(root, bytenr, num_bytes, 1);
 
@@ -2511,8 +2502,6 @@
 	 */
 	if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID &&
 	    owner_objectid < BTRFS_FIRST_FREE_OBJECTID) {
-		mutex_lock(&root->fs_info->pinned_mutex);
-
 		/* unlocks the pinned mutex */
 		btrfs_update_pinned_extents(root, bytenr, num_bytes, 1);
 		update_reserved_extents(root, bytenr, num_bytes, 0);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index fc9b87a..2871609 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -262,11 +262,9 @@
 			      struct extent_buffer *eb,
 			      struct walk_control *wc, u64 gen)
 {
-	if (wc->pin) {
-		mutex_lock(&log->fs_info->pinned_mutex);
+	if (wc->pin)
 		btrfs_update_pinned_extents(log->fs_info->extent_root,
 					    eb->start, eb->len, 1);
-	}
 
 	if (btrfs_buffer_uptodate(eb, gen)) {
 		if (wc->write)