btrfs: Enhance error output for write time tree checker

Unlike read time tree checker errors, write time error can't be
inspected by "btrfs inspect dump-tree", so we need extra information to
determine what's going wrong.

The patch will add the following output for write time tree checker
error:

- The content of the offending tree block
  To help determining if it's a false alert.

- Kernel WARN_ON() for debug build
  This is helpful for us to detect unexpected write time tree checker
  error, especially fstests could catch the dmesg.
  Since the WARN_ON() is only triggered for write time tree checker,
  test cases utilizing dm-error won't trigger this WARN_ON(), thus no
  extra noise.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 0bc6e3e9f7c34d8426cefed9ef36b94082adbddd..f54a4782d18cf329fe947a637098599c18b27a72 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -545,9 +545,11 @@ static int csum_dirty_buffer(struct btrfs_fs_info *fs_info, struct page *page)
                ret = btrfs_check_leaf_full(eb);
 
        if (ret < 0) {
+               btrfs_print_tree(eb, 0);
                btrfs_err(fs_info,
                "block=%llu write time tree block corruption detected",
                          eb->start);
+               WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
                return ret;
        }
        write_extent_buffer(eb, result, 0, csum_size);