Btrfs: check return value of read_tree_block()

This patch is checking return value of read_tree_block(),
and if it is NULL, error processing.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index c863c8447015..58250e09eb05 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1724,6 +1724,7 @@ again:
 
                         eb = read_tree_block(dest, old_bytenr, blocksize,
                                              old_ptr_gen);
+                        BUG_ON(!eb);
                         btrfs_tree_lock(eb);
                         if (cow) {
                                 ret = btrfs_cow_block(trans, dest, eb, parent,
@@ -2513,6 +2514,10 @@ static int do_relocation(struct btrfs_trans_handle *trans,
                 blocksize = btrfs_level_size(root, node->level);
                 generation = btrfs_node_ptr_generation(upper->eb, slot);
                 eb = read_tree_block(root, bytenr, blocksize, generation);
+                if (!eb) {
+                        err = -EIO;
+                        goto next;
+                }
                 btrfs_tree_lock(eb);
                 btrfs_set_lock_blocking(eb);
 
@@ -2670,6 +2675,7 @@ static int get_tree_block_key(struct reloc_control *rc,
         BUG_ON(block->key_ready);
         eb = read_tree_block(rc->extent_root, block->bytenr,
                              block->key.objectid, block->key.offset);
+        BUG_ON(!eb);
         WARN_ON(btrfs_header_level(eb) != block->level);
         if (block->level == 0)
                 btrfs_item_key_to_cpu(eb, &block->key, 0);