nfsd41: hange from page to memory based drc limits

NFSD_SLOT_CACHE_SIZE is the size of all encoded operation responses
(excluding the sequence operation) that we want to cache.

For now, keep NFSD_SLOT_CACHE_SIZE at PAGE_SIZE. It will be reduced
when the DRC is changed from page based to memory based.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfs4state.c

@@ -414,31 +414,31 @@ gen_sessionid(struct nfsd4_session *ses)
 
 /*
  * Give the client the number of slots it requests bound by
- * NFSD_MAX_SLOTS_PER_SESSION and by sv_drc_max_pages.
+ * NFSD_MAX_SLOTS_PER_SESSION and by nfsd_drc_max_mem.
  *
- * If we run out of pages (sv_drc_pages_used == sv_drc_max_pages) we
- * should (up to a point) re-negotiate active sessions and reduce their
- * slot usage to make rooom for new connections. For now we just fail the
- * create session.
+ * If we run out of reserved DRC memory we should (up to a point) re-negotiate
+ * active sessions and reduce their slot usage to make rooom for new
+ * connections. For now we just fail the create session.
  */
 static int set_forechannel_maxreqs(struct nfsd4_channel_attrs *fchan)
 {
-	int np;
+	int mem;
 
 	if (fchan->maxreqs < 1)
 		return nfserr_inval;
 	else if (fchan->maxreqs > NFSD_MAX_SLOTS_PER_SESSION)
 		fchan->maxreqs = NFSD_MAX_SLOTS_PER_SESSION;
 
-	np = fchan->maxreqs * NFSD_PAGES_PER_SLOT;
+	mem = fchan->maxreqs * NFSD_SLOT_CACHE_SIZE;
 
 	spin_lock(&nfsd_drc_lock);
-	if (np + nfsd_drc_pages_used > nfsd_drc_max_pages)
-		np = nfsd_drc_max_pages - nfsd_drc_pages_used;
-	nfsd_drc_pages_used += np;
+	if (mem + nfsd_drc_mem_used > nfsd_drc_max_mem)
+		mem = ((nfsd_drc_max_mem - nfsd_drc_mem_used) /
+				NFSD_SLOT_CACHE_SIZE) * NFSD_SLOT_CACHE_SIZE;
+	nfsd_drc_mem_used += mem;
 	spin_unlock(&nfsd_drc_lock);
 
-	fchan->maxreqs = np / NFSD_PAGES_PER_SLOT;
+	fchan->maxreqs = mem / NFSD_SLOT_CACHE_SIZE;
 	if (fchan->maxreqs == 0)
 		return nfserr_resource;
 	return 0;
@@ -465,9 +465,7 @@ static int init_forechannel_attrs(struct svc_rqst *rqstp,
 		fchan->maxresp_sz = maxcount;
 	session_fchan->maxresp_sz = fchan->maxresp_sz;
 
-	/* Set the max response cached size our default which is
-	 * a multiple of PAGE_SIZE and small */
-	session_fchan->maxresp_cached = NFSD_PAGES_PER_SLOT * PAGE_SIZE;
+	session_fchan->maxresp_cached = NFSD_SLOT_CACHE_SIZE;
 	fchan->maxresp_cached = session_fchan->maxresp_cached;
 
 	/* Use the client's maxops if possible */
@@ -585,7 +583,7 @@ free_session(struct kref *kref)
 		nfsd4_release_respages(e->ce_respages, e->ce_resused);
 	}
 	spin_lock(&nfsd_drc_lock);
-	nfsd_drc_pages_used -= ses->se_fchannel.maxreqs * NFSD_PAGES_PER_SLOT;
+	nfsd_drc_mem_used -= ses->se_fchannel.maxreqs * NFSD_SLOT_CACHE_SIZE;
 	spin_unlock(&nfsd_drc_lock);
 	kfree(ses);
 }

fs/nfsd/nfssvc.c

@@ -74,8 +74,8 @@ struct svc_serv 		*nfsd_serv;
  * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
  */
 spinlock_t	nfsd_drc_lock;
-unsigned int	nfsd_drc_max_pages;
-unsigned int	nfsd_drc_pages_used;
+unsigned int	nfsd_drc_max_mem;
+unsigned int	nfsd_drc_mem_used;
 
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 static struct svc_stat	nfsd_acl_svcstats;
@@ -247,12 +247,11 @@ void nfsd_reset_versions(void)
 static void set_max_drc(void)
 {
 	#define NFSD_DRC_SIZE_SHIFT	10
-	nfsd_drc_max_pages = nr_free_buffer_pages()
-						>> NFSD_DRC_SIZE_SHIFT;
-	nfsd_drc_pages_used = 0;
+	nfsd_drc_max_mem = (nr_free_buffer_pages()
+					>> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
+	nfsd_drc_mem_used = 0;
 	spin_lock_init(&nfsd_drc_lock);
-	dprintk("%s nfsd_drc_max_pages %u\n", __func__,
-		nfsd_drc_max_pages);
+	dprintk("%s nfsd_drc_max_mem %u \n", __func__, nfsd_drc_max_mem);
 }
 
 int nfsd_create_serv(void)

include/linux/nfsd/nfsd.h

@@ -57,8 +57,8 @@ extern u32			nfsd_supported_minorversion;
 extern struct mutex		nfsd_mutex;
 extern struct svc_serv		*nfsd_serv;
 extern spinlock_t		nfsd_drc_lock;
-extern unsigned int		nfsd_drc_max_pages;
-extern unsigned int		nfsd_drc_pages_used;
+extern unsigned int		nfsd_drc_max_mem;
+extern unsigned int		nfsd_drc_mem_used;
 
 extern struct seq_operations nfs_exports_op;
 

include/linux/nfsd/state.h

@@ -96,6 +96,7 @@ struct nfs4_cb_conn {
 #define NFSD_MAX_SLOTS_PER_SESSION	128
 /* Maximum number of pages per slot cache entry */
 #define NFSD_PAGES_PER_SLOT	1
+#define NFSD_SLOT_CACHE_SIZE		PAGE_SIZE
 /* Maximum number of operations per session compound */
 #define NFSD_MAX_OPS_PER_COMPOUND	16