Merge branch 'misc-4.7' into for-chris-4.7-20160516

1 files changed, 15 insertions, 3 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4e47849d7427..070c1dad42bd 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2517,6 +2517,7 @@ int open_ctree(struct super_block *sb,
         int num_backups_tried = 0;
         int backup_index = 0;
         int max_active;
+        bool cleaner_mutex_locked = false;
 
         tree_root = fs_info->tree_root = btrfs_alloc_root(fs_info, GFP_KERNEL);
         chunk_root = fs_info->chunk_root = btrfs_alloc_root(fs_info, GFP_KERNEL);
@@ -2997,6 +2998,13 @@ retry_root_backup:
                 goto fail_sysfs;
         }
 
+        /*
+         * Hold the cleaner_mutex thread here so that we don't block
+         * for a long time on btrfs_recover_relocation.  cleaner_kthread
+         * will wait for us to finish mounting the filesystem.
+         */
+        mutex_lock(&fs_info->cleaner_mutex);
+        cleaner_mutex_locked = true;
         fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
                                                "btrfs-cleaner");
         if (IS_ERR(fs_info->cleaner_kthread))
@@ -3056,10 +3064,8 @@ retry_root_backup:
                 ret = btrfs_cleanup_fs_roots(fs_info);
                 if (ret)
                         goto fail_qgroup;
-
-                mutex_lock(&fs_info->cleaner_mutex);
+                /* We locked cleaner_mutex before creating cleaner_kthread. */
                 ret = btrfs_recover_relocation(tree_root);
-                mutex_unlock(&fs_info->cleaner_mutex);
                 if (ret < 0) {
                         printk(KERN_WARNING
                                "BTRFS: failed to recover relocation\n");
@@ -3067,6 +3073,8 @@ retry_root_backup:
                         goto fail_qgroup;
                 }
         }
+        mutex_unlock(&fs_info->cleaner_mutex);
+        cleaner_mutex_locked = false;
 
         location.objectid = BTRFS_FS_TREE_OBJECTID;
         location.type = BTRFS_ROOT_ITEM_KEY;
@@ -3180,6 +3188,10 @@ fail_cleaner:
         filemap_write_and_wait(fs_info->btree_inode->i_mapping);
 
 fail_sysfs:
+        if (cleaner_mutex_locked) {
+                mutex_unlock(&fs_info->cleaner_mutex);
+                cleaner_mutex_locked = false;
+        }
         btrfs_sysfs_remove_mounted(fs_info);
 
 fail_fsdev_sysfs: