ext4: ensure enough credits in ext4_ext_shift_path_extents

hulk inclusion
category: bugfix
bugzilla: 182995 https://gitee.com/openeuler/kernel/issues/I4DDEL

---------------------------

Like ext4_ext_rm_leaf, we can ensure that there are enough credits
before every call that will consume credits.  As part of this fix we
fold the functionality of ext4_access_path() into
ext4_ext_shift_path_extents().  This change is needed as a preparation
for the next bugfix patch.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20210903062748.4118886-3-yangerkun@huawei.com


Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>