jbd2: add fast_commit space check

If JBD2_FEATURE_INCOMPAT_FAST_COMMIT bit is set, it means the journal
have fast commit records need to recover, so the fast commit size
should not be too large, and the leftover normal journal size should
never less than JBD2_MIN_JOURNAL_BLOCKS. If it happens, the
journal->j_last is likely to be wrong and will probably lead to
incorrect journal recovery. So add a check into the
journal_check_superblock(), and drop the pointless check when
initializing the fastcommit parameters.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230811063610.2980059-8-yi.zhang@huaweicloud.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>