FYI, we noticed the following commit:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
commit 2be63d5ce929603d4e7cedabd9e992eb34a0ff95 ("Btrfs: fix file loss on log replay after renaming a file and fsync")

on test machine: vm-kbuild-4G: 4 threads qemu-system-x86_64 -enable-kvm -cpu qemu64,+ssse3 with 4G memory

caused below changes:

[  161.757935] BTRFS warning (device dm-0): block group 29360128 has wrong amount of free space
[  161.759875] BTRFS warning (device dm-0): failed to load free space cache for block group 29360128, rebuilding it now
[  161.818413] BTRFS: checking UUID tree


FYI, raw QEMU command line is:

	qemu-system-x86_64 -enable-kvm -cpu qemu64,+ssse3 -kernel /pkg/linux/x86_64-rhel/gcc-4.9/2be63d5ce929603d4e7cedabd9e992eb34a0ff95/vmlinuz-4.5.0-rc6-00079-g2be63d5 -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-4G-1/bisect_xfstests-4HDD-btrfs-generic-quick1-debian-x86_64-2015-02-07.cgz-x86_64-rhel-2be63d5ce929603d4e7cedabd9e992eb34a0ff95-20160513-33095-7gu30b-0.yaml ARCH=x86_64 kconfig=x86_64-rhel branch=scsi/fixes commit=2be63d5ce929603d4e7cedabd9e992eb34a0ff95 BOOT_IMAGE=/pkg/linux/x86_64-rhel/gcc-4.9/2be63d5ce929603d4e7cedabd9e992eb34a0ff95/vmlinuz-4.5.0-rc6-00079-g2be63d5 max_uptime=3600 RESULT_ROOT=/result/xfstests/4HDD-btrfs-generic-quick1/vm-kbuild-4G/debian-x86_64-2015-02-07.cgz/x86_64-rhel/gcc-4.9/2be63d5ce929603d4e7cedabd9e992eb34a0ff95/0 LKP_SERVER=inn earlyprintk=ttyS0,115200 systemd.log_level=err debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal rw ip=::::vm-kbuild-4G-1::dhcp'  -initrd /fs/sdf1/initrd-vm-kbuild-4G-1 -m 4096 -smp 4 -device e1000,netdev=net0 -netdev user,id=net0,hostfwd=tcp::23032-:22 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -drive file=/fs/sdf1/disk0-vm-kbuild-4G-1,media=disk,if=virtio -drive file=/fs/sdf1/disk1-vm-kbuild-4G-1,media=disk,if=virtio -drive file=/fs/sdf1/disk2-vm-kbuild-4G-1,media=disk,if=virtio -drive file=/fs/sdf1/disk3-vm-kbuild-4G-1,media=disk,if=virtio -drive file=/fs/sdf1/disk4-vm-kbuild-4G-1,media=disk,if=virtio -drive file=/fs/sdf1/disk5-vm-kbuild-4G-1,media=disk,if=virtio -drive file=/fs/sdf1/disk6-vm-kbuild-4G-1,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-kbuild-4G-1 -serial file:/dev/shm/kboot/serial-vm-kbuild-4G-1 -daemonize -display none -monitor null 


To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml


Thanks,
Xiaolong