resize2fs results in "permission denied"

problem:
after successful "lvextend -L +15G" , resize2fs gets "permission denied".

strace says:

open("/dev/mapper/vg_phoesrv2b-varlog", O_RDONLY|O_EXCL) = -1 EACCES (Permission denied) open("/dev/mapper/vg_phoesrv2b-varlog", O_RDWR) = -1 EACCES (Permission denied)

ls:

	brw-rw---- 1 root disk 254, 44 Apr 11 23:15 /dev/mapper/vg_phoesrv2b-varlog 

lvs:

	varlog     vg_phoesrv2b -wi-ao--  25,00g

system:

	debian 7.8
	resize2fs 1.42.5 (29-Jul-2012)
	lvm2 2.02.95-8
	linux 3.18.9

never seen that one. what's going on?

/dev/mapper contains device nodes, e.g.:

    brw-rw---- 1 root disk 254, 73 Apr 11 23:15 vg_phoesrv2b-lvsnap

those should be symlinks ( except for/dev/mapper/control ):

    vg_phoesrv2b-lvsnap -> ../dm-31

solution:
rm /dev/mapper/vg_phoesrv2b-lvsnap
udevadm trigger

I wonder, no one should mess directly with /dev/mapper ! Better would be to fill a bug report (reproducible/consistent), if it's not fixed in recent lvm releases.

Thanks.