nfsd4: fix nfs4 stateid leak
nfsd4: fix nfs4 stateid leak

Processes that open and close multiple files may end up setting this
oo_last_closed_stid without freeing what was previously pointed to.
This can result in a major leak, visible for example by watching the
nfsd4_stateids line of /proc/slabinfo.

Reported-by: Cyril B. <f1d4c4e63b10952206910fb4371fbd677f770c6d@excellency.fr>
Tested-by: Cyril B. <f1d4c4e63b10952206910fb4371fbd677f770c6d@excellency.fr>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org
Signed-off-by: J. Bruce Fields <51738506c1b2ccb0761f23bdc612c93babf738ea@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas