Cephfs with kernel client mtime stuck when multiple clients append to file
File modification timestamp stop updating when multiple clients(from multiple nodes) append to file at same time or few seconds after each other.
node1 => echo "test1" >> /mnt/ceph/mtime_test
node2 => echo "test2" >> /mnt/ceph/mtime_test
node1 => echo ....
node2 => echo ....
node1 => watch stat /mnt/ceph/mtime_test # first 1-2 change and no change even after few minutes of waiting
Timestam start working again, when no client appending to file for 20-120s
Sometimes mtime not updating even when only one client appending to file, but its rare.
OS: Ubuntu 18.04.4, Ubuntu 20.04, fedora 32
Kernel: 5.4.0-40-generic, 4.15.0-108-generic,4.15.0-109-generic or even latest 5.7.7/5.7.8
Ceph v15.2.3, v15.2.4, 14.2.10
No problem except bad performance with ceph-fuse client.