nfsd4.1: fix session memory use calculation

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>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index fcb9817881a15d5f558aacdb5e61d20d3d7e4b1a..c17137110412947e9385740b1b0363f6f761bdb1 100644 (file)
--- 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);