Btrfs: stop all workers after we free block groups

Stefan was hitting a panic in the async worker stuff because we had outstanding
read bios while we were stopping the worker threads.  You could reproduce this
easily if you mount -o nospace_cache and ran generic/273.  This is because the
caching thread stuff is still going and we were stopping all the worker threads.
We need to stop the workers after this work is done, and the free block groups
code will wait for all the caching threads to stop first so we don't run into
this problem.  With this patch we no longer panic.  Thanks,

Cc: stable@vger.kernel.org
Reported-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 419968e3eaa00d899351dff426594296511b2866..b0ea9f4bbc7037348f3eafdc90bf59302d02b656 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3637,12 +3637,12 @@ int close_ctree(struct btrfs_root *root)
                       percpu_counter_sum(&fs_info->delalloc_bytes));
        }
 
-       btrfs_stop_all_workers(fs_info);
-
        del_fs_roots(fs_info);
 
        btrfs_free_block_groups(fs_info);
 
+       btrfs_stop_all_workers(fs_info);
+
        free_root_pointers(fs_info, 1);
 
        iput(fs_info->btree_inode);