ext4: introduce s_min_folio_order for future BS > PS support

ext4: introduce s_min_folio_order for future BS > PS support

This commit introduces the s_min_folio_order field to the ext4_sb_info
structure. This field will store the minimum folio order required by the
current filesystem, laying groundwork for future support of block sizes
greater than PAGE_SIZE.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Message-ID: <20251121090654.631996-7-libaokun@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>