btrfs: add might_sleep() annotations

[ Upstream commit a4c853af0c511d7e0f7cb306bbc8a4f1dbdb64ca ]

Add annotations to functions that might sleep due to allocations or IO
and could be called from various contexts. In case of btrfs_search_slot
it's not obvious why it would sleep:

    btrfs_search_slot
      setup_nodes_for_search
        reada_for_balance
          btrfs_readahead_node_child
            btrfs_readahead_tree_block
              btrfs_find_create_tree_block
                alloc_extent_buffer
                  kmem_cache_zalloc
                    /* allocate memory non-atomically, might sleep */
                    kmem_cache_alloc(GFP_NOFS|__GFP_NOFAIL|__GFP_ZERO)
              read_extent_buffer_pages
                submit_extent_page
                  /* disk IO, might sleep */
                  submit_one_bio

Other examples where the sleeping could happen is in 3 places might
sleep in update_qgroup_limit_item(), as shown below:

  update_qgroup_limit_item
    btrfs_alloc_path
      /* allocate memory non-atomically, might sleep */
      kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS)

Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: 3ed51857a50f ("btrfs: add a sanity check for btrfs root in btrfs_search_slot()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 0b8c8b5094efb3f328855d3b81f02b41f20b353e..af6ddf1f913aef685d34a7e2651229c3a9259778 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -76,6 +76,8 @@ size_t __attribute_const__ btrfs_get_num_csums(void)
 
 struct btrfs_path *btrfs_alloc_path(void)
 {
+       might_sleep();
+
        return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
 }
 
@@ -1774,6 +1776,8 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
        int min_write_lock_level;
        int prev_cmp;
 
+       might_sleep();
+
        lowest_level = p->lowest_level;
        WARN_ON(lowest_level && ins_len > 0);
        WARN_ON(p->nodes[0] != NULL);