gmirror causes panic under 9.0-STABLE

[Andrey Zonov]

Hi,

I've got repeatable panics with gmirror and ufs.  The test case is the
following:
# gmirror label -v test /dev/da1b
# newfs /dev/mirror/test
# while :; do gmirror label -v test /dev/da1b; mount /dev/mirror/test
/mnt; dd if=/dev/zero of=/mnt/test count=100 bs=1m; umount -f /mnt;
gmirror remove test da1b; done

After a while I've got panic with such DDB backtrace:

db:0:kdb.enter.default>  bt
Tracing pid 5240 tid 100075 td 0xfffffe0001e47460
_sx_xlock_hard() at _sx_xlock_hard+0xb3
g_mirror_access() at g_mirror_access+0x262
g_access() at g_access+0x162
g_vfs_open() at g_vfs_open+0xb3
ffs_mount() at ffs_mount+0xb4b
vfs_donmount() at vfs_donmount+0x1072
sys_nmount() at sys_nmount+0x66
amd64_syscall() at amd64_syscall+0x5bf
Xfast_syscall() at Xfast_syscall+0xf7
--- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0x800a8746c, rsp =
0x7fffffffcb58, rbp = 0x801008048 ---


-- 
Andrey Zonov