The helper jbd2_handle_buffer_credits() doesn't correctly handle reserved
handles which can lead to crashes. Fix it getting of journal pointer to
work for reserved handles as well.
Fixes: a9a8344ee1 ("ext4, jbd2: Provide accessor function for handle credits")
Reported-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191115102210.29445-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
3c845acd02