Commit 52427260 ("btrfs: Handle delalloc error correctly to avoid
ordered extent hang") introduced btrfs_cleanup_ordered_extents() to cleanup
submitted ordered extents. However, it does not clear the ordered bit
(Private2) of corresponding pages. Thus, the following BUG occurs from
free_pages_check_bad() (on btrfs/125 with nospace_cache).

BUG: Bad page state in process btrfs  pfn:3fa787
page:ffffdf2acfe9e1c0 count:0 mapcount:0 mapping:          (null) index:0xd
flags: 0x8000000000002008(uptodate|private_2)
raw: 8000000000002008 0000000000000000 000000000000000d 00000000ffffffff
raw: ffffdf2acf5c1b20 ffffb443802238b0 0000000000000000 0000000000000000
page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
bad because of flags: 0x2000(private_2)

This patch clears the flag same as other places calling
btrfs_dec_test_ordered_pending() for every page in the specified range.

Fixes: 52427260 ("btrfs: Handle delalloc error correctly to avoid ordered extent hang")
Cc: <stable@vger.kernel.org> # 4.12
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>