nfsd: give out fewer session slots as limit approaches
[ Upstream commit de766e570413bd0484af0b580299b495ada625c3 ]
Instead of granting client's full requests until we hit our DRC size
limit and then failing CREATE_SESSIONs (and hence mounts) completely,
start granting clients smaller slot tables as we approach the limit.
The factor chosen here is pretty much arbitrary.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 3656f87..0aacd1c 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1507,6 +1507,11 @@
spin_lock(&nfsd_drc_lock);
avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION,
nfsd_drc_max_mem - nfsd_drc_mem_used);
+ /*
+ * Never use more than a third of the remaining memory,
+ * unless it's the only way to give this client a slot:
+ */
+ avail = clamp_t(int, avail, slotsize, avail/3);
num = min_t(int, num, avail / slotsize);
nfsd_drc_mem_used += num * slotsize;
spin_unlock(&nfsd_drc_lock);