Description of problem:
Default Fedora Workstation (live) final TC3 install (autopartitioning) in kvm to qcow2 with libvirt cache=none (does not happen if cache=unsafe). Qcow2 file is on Btrfs. Problem doesn't happen if qcow2 is on XFS. Clean dup of bug 1204569. Possible dup of bug 1220950.

Additional info:
reporter:       libreport-2.5.1
WARNING: CPU: 0 PID: 2543 at fs/block_dev.c:57 __blkdev_put+0xc1/0x220()
Modules linked in: xfs libcrc32c btrfs fcoe libfcoe libfc scsi_transport_fc iscsi_ibft iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi sha256_ssse3 dm_crypt vfat fat dm_round_robin dm_multipath raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq raid1 raid0 bnep bluetooth rfkill uinput nf_conntrack_netbios_ns nf_conntrack_broadcast fuse ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ebtable_nat ebtable_broute bridge ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw snd_hda_codec_generic snd_hda_intel
 snd_hda_controller snd_hda_codec snd_hwdep snd_seq snd_seq_device snd_pcm ppdev iosf_mbi snd_timer serio_raw snd parport_pc soundcore i2c_piix4 acpi_cpufreq parport nfsd auth_rpcgss nfs_acl lockd grace isofs squashfs 8021q garp stp llc mrp virtio_net virtio_console virtio_blk virtio_balloon qxl drm_kms_helper ttm drm crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel virtio_pci virtio_ring virtio ata_generic pata_acpi scsi_dh_rdac scsi_dh_emc scsi_dh_alua sunrpc loop
CPU: 0 PID: 2543 Comm: mke2fs Not tainted 4.0.1-300.fc22.x86_64 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014
 0000000000000000 00000000bb7beb49 ffff8800b93ffdb8 ffffffff817819a8
 0000000000000000 0000000000000000 ffff8800b93ffdf8 ffffffff8109c60a
 0000000000000000 ffff8800bc026ef8 ffff8800bc026d80 ffff8800bc026e70
Call Trace:
 [<ffffffff817819a8>] dump_stack+0x45/0x57
 [<ffffffff8109c60a>] warn_slowpath_common+0x8a/0xc0
 [<ffffffff8109c73a>] warn_slowpath_null+0x1a/0x20
 [<ffffffff81257c21>] __blkdev_put+0xc1/0x220
 [<ffffffff81258210>] blkdev_put+0x50/0x130
 [<ffffffff81258315>] blkdev_close+0x25/0x30
 [<ffffffff8121edaf>] __fput+0xdf/0x1f0
 [<ffffffff8121ef0e>] ____fput+0xe/0x10
 [<ffffffff810b9927>] task_work_run+0xa7/0xe0
 [<ffffffff81013d0d>] do_notify_resume+0x9d/0xa0
 [<ffffffff817882e3>] int_signal+0x12/0x17