Ceph » Linux kernel client

After I upgraded my cephfs.ko clients from 4.7.9 to 4.8.6, I had to resort to ceph-fuse to access a cephfs I've had for several years. cephfs.ko can list directories all right, but attempting to read files yields EIO, and dmesg logs such stuff as:
WARNING: CPU: 0 PID: 25961 at net/ceph/osd_client.c:550 ceph_osdc_alloc_messages+0x171/0x1a0 [libceph]
[38009.116654] Call Trace:
[38009.116662] [<ffffffffb13e5ebd>] dump_stack+0x63/0x86
[38009.116669] [<ffffffffb10a0e8b>] __warn+0xcb/0xf0
[38009.116677] [<ffffffffb10a0fbd>] warn_slowpath_null+0x1d/0x20
[38009.116703] [<ffffffffc0b22151>] ceph_osdc_alloc_messages+0x171/0x1a0 [libceph]
[38009.116730] [<ffffffffc0b81952>] ceph_pool_perm_check+0x5e2/0x980 [ceph]
[38009.116758] [<ffffffffc0b88c2b>] ceph_get_caps+0x4b/0x3d0 [ceph]
[38009.116782] [<ffffffffc0b7a2f0>] ? ceph_write_iter+0xbe0/0xbe0 [ceph]
[38009.116789] [<ffffffffb12725a4>] ? mntput+0x24/0x40
[38009.116796] [<ffffffffb125ad80>] ? terminate_walk+0xe0/0xf0
[38009.116821] [<ffffffffc0b7a725>] ceph_read_iter+0xe5/0xb40 [ceph]
[38009.116848] [<ffffffffc0b85019>] ? __ceph_caps_issued_mask+0x1e9/0x1f0 [ceph]
[38009.116856] [<ffffffffb124f7e2>] __vfs_read+0xe2/0x150
[38009.116863] [<ffffffffb12508c6>] vfs_read+0x96/0x130
[38009.116870] [<ffffffffb1251da5>] SyS_read+0x55/0xc0
[38009.116877] [<ffffffffb1802572>] entry_SYSCALL_64_fastpath+0x1a/0xa4
[38009.116923] --[ end trace 6bff712d7c4cbd24 ]---
[38024.526160] libceph: tid 1 pool does not exist
[38024.526184] libceph: tid 2 pool does not exist