[PATCH 1/2] nfsd4.1: fix session memory use calculation

["J. Bruce Fields" <bfields@citi.umich.edu>]

Unbalanced calculations on creation and destruction of sessions could
cause our estimate of cache memory used to become negative, sometimes
resulting in spurious SERVERFAULT returns to client CREATE_SESSION
requests.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
---
 fs/nfsd/nfs4state.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index fcb9817..c171371 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -629,10 +629,13 @@ void
 free_session(struct kref *kref)
 {
 	struct nfsd4_session *ses;
+	int mem;
 
 	ses = container_of(kref, struct nfsd4_session, se_ref);
 	spin_lock(&nfsd_drc_lock);
-	nfsd_drc_mem_used -= ses->se_fchannel.maxreqs * NFSD_SLOT_CACHE_SIZE;
+	mem = ses->se_fchannel.maxreqs
+		* (ses->se_fchannel.maxresp_cached - NFSD_MIN_HDR_SEQ_SZ);
+	nfsd_drc_mem_used -= mem;
 	spin_unlock(&nfsd_drc_lock);
 	free_session_slots(ses);
 	kfree(ses);
-- 
1.6.3.3