ext4: make ext4_insert_delayed_block() insert multi-blocks

ext4: make ext4_insert_delayed_block() insert multi-blocks

Rename ext4_insert_delayed_block() to ext4_insert_delayed_blocks(),
pass length parameter to make it insert multiple delalloc blocks at a
time. For non-bigalloc case, just reserve len blocks and insert delalloc
extent. For bigalloc case, we can ensure that the clusters in the middle
of a extent must be unallocated, we only need to check whether the start
and end clusters are delayed/allocated. We should subtract the space for
the start and/or end block(s) if they are allocated.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20240517124005.347221-10-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>