Patch "Btrfs: fix mount -o clear_cache,space_cache=v2" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

Btrfs: fix mount -o clear_cache,space_cache=v2

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
btrfs-fix-mount-o-clear_cache-space_cache-v2.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Omar Sandoval <[email protected]>
Date: Thu, 22 Sep 2016 17:24:21 -0700
Subject: Btrfs: fix mount -o clear_cache,space_cache=v2
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From: Omar Sandoval <[email protected]>

commit f8d468a15c22b954b379aa0c74914d5068448fb1 upstream.

We moved the code for creating the free space tree the first time that it's enabled, but didn't move the clearing code along with it. This breaks my (undocumented) intention that mount -o clear_cache,space_cache=v2 would clear the free space tree and then recreate it.

---
 fs/btrfs/disk-io.c |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

@@ -3129,6 +3129,18 @@ retry_root_backup:
 	if (sb->s_flags & MS_RDONLY)
 		return 0;
 
+	if (btrfs_test_opt(fs_info, CLEAR_CACHE) &&
+	    btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
+		btrfs_info(fs_info, "clearing free space tree");
+		ret = btrfs_clear_free_space_tree(fs_info);
+		if (ret) {
+			btrfs_warn(fs_info,
+				   "failed to clear free space tree: %d", ret);
+			close_ctree(tree_root);
+			return ret;
+		}
+	}
+
 	if (btrfs_test_opt(tree_root->fs_info, FREE_SPACE_TREE) &&
 	    !btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
 		btrfs_info(fs_info, "creating free space tree");

@@ -3166,18 +3178,6 @@ retry_root_backup:
 
 	btrfs_qgroup_rescan_resume(fs_info);
 
-	if (btrfs_test_opt(tree_root->fs_info, CLEAR_CACHE) &&
-	    btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
-		btrfs_info(fs_info, "clearing free space tree");
-		ret = btrfs_clear_free_space_tree(fs_info);
-		if (ret) {
-			btrfs_warn(fs_info,
-				"failed to clear free space tree: %d", ret);
-			close_ctree(tree_root);
-			return ret;
-		}
-	}
-
 	if (!fs_info->uuid_root) {
 		btrfs_info(fs_info, "creating UUID tree");
 		ret = btrfs_create_uuid_tree(fs_info);

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/btrfs-fix-free-space-tree-bitmaps-on-big-endian-systems.patch queue-4.8/btrfs-catch-invalid-free-space-trees.patch queue-4.8/btrfs-fix-mount-o-clear_cache-space_cache-v2.patch