ext4-fs failed delayed block allocation dangerous? data lost?

edit

I have installed Fedora 26 Gnome on a ssd. root is on partition sdb4 separate from /home

on each boot dmesg shows: EXT4-fs (sdb4): Delayed block allocation failed for inode 323322 at logical offset 1197 with max blocks 3 with error 121 EXT4-fs (sdb4): This should not happen!! Data will be lost

extended test of ssd with smart passed. no error. fsck.ext4 for all paritions with ext4 passed with no error. gdisk -l /dev/sdb is ok

Is it really dangerous? Will data be lost?