NFSv4.1: make deviceid cache global

[karo-tx-linux.git] / fs / nfs / pnfs_dev.c

diff --git a/fs/nfs/pnfs_dev.c b/fs/nfs/pnfs_dev.c
new file mode 100644 (file)
index 0000000..bf05189
--- /dev/null
+++ b/fs/nfs/pnfs_dev.c
@@ -0,0 +1,156 @@
+/*
+ *  Device operations for the pnfs client.
+ *
+ *  Copyright (c) 2002
+ *  The Regents of the University of Michigan
+ *  All Rights Reserved
+ *
+ *  Dean Hildebrand <dhildebz@umich.edu>
+ *  Garth Goodson   <Garth.Goodson@netapp.com>
+ *
+ *  Permission is granted to use, copy, create derivative works, and
+ *  redistribute this software and such derivative works for any purpose,
+ *  so long as the name of the University of Michigan is not used in
+ *  any advertising or publicity pertaining to the use or distribution
+ *  of this software without specific, written prior authorization. If
+ *  the above copyright notice or any other identification of the
+ *  University of Michigan is included in any copy of any portion of
+ *  this software, then the disclaimer below must also be included.
+ *
+ *  This software is provided as is, without representation or warranty
+ *  of any kind either express or implied, including without limitation
+ *  the implied warranties of merchantability, fitness for a particular
+ *  purpose, or noninfringement.  The Regents of the University of
+ *  Michigan shall not be liable for any damages, including special,
+ *  indirect, incidental, or consequential damages, with respect to any
+ *  claim arising out of or in connection with the use of the software,
+ *  even if it has been or is hereafter advised of the possibility of
+ *  such damages.
+ */
+
+#include "pnfs.h"
+
+#define NFSDBG_FACILITY                NFSDBG_PNFS
+
+/*
+ * Device ID RCU cache. A device ID is unique per server and layout type.
+ */
+#define NFS4_DEVICE_ID_HASH_BITS       5
+#define NFS4_DEVICE_ID_HASH_SIZE       (1 << NFS4_DEVICE_ID_HASH_BITS)
+#define NFS4_DEVICE_ID_HASH_MASK       (NFS4_DEVICE_ID_HASH_SIZE - 1)
+
+static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
+static DEFINE_SPINLOCK(nfs4_deviceid_lock);
+
+void
+nfs4_print_deviceid(const struct nfs4_deviceid *id)
+{
+       u32 *p = (u32 *)id;
+
+       dprintk("%s: device id= [%x%x%x%x]\n", __func__,
+               p[0], p[1], p[2], p[3]);
+}
+EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
+
+static inline u32
+nfs4_deviceid_hash(const struct nfs4_deviceid *id)
+{
+       unsigned char *cptr = (unsigned char *)id->data;
+       unsigned int nbytes = NFS4_DEVICEID4_SIZE;
+       u32 x = 0;
+
+       while (nbytes--) {
+               x *= 37;
+               x += *cptr++;
+       }
+       return x & NFS4_DEVICE_ID_HASH_MASK;
+}
+
+/*
+ * Lookup a deviceid in cache and get a reference count on it if found
+ *
+ * @clp nfs_client associated with deviceid
+ * @id deviceid to look up
+ */
+struct nfs4_deviceid_node *
+nfs4_find_get_deviceid(const struct nfs_client *clp, const struct nfs4_deviceid *id)
+{
+       struct nfs4_deviceid_node *d;
+       struct hlist_node *n;
+       long hash = nfs4_deviceid_hash(id);
+
+       rcu_read_lock();
+       hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node) {
+               if (d->nfs_client == clp && !memcmp(&d->deviceid, id, sizeof(*id))) {
+                       if (!atomic_inc_not_zero(&d->ref))
+                               goto fail;
+                       rcu_read_unlock();
+                       return d;
+               }
+       }
+fail:
+       rcu_read_unlock();
+       return NULL;
+}
+EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
+
+void
+nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
+                       const struct nfs_client *nfs_client,
+                       const struct nfs4_deviceid *id)
+{
+       d->nfs_client = nfs_client;
+       d->deviceid = *id;
+}
+EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);
+
+/*
+ * Uniquely initialize and insert a deviceid node into cache
+ *
+ * @new new deviceid node
+ *      Note that the caller must set up new->nfs_client and new->deviceid
+ *
+ * @ret the inserted node, if none found, otherwise, the found entry.
+ */
+struct nfs4_deviceid_node *
+nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
+{
+       struct nfs4_deviceid_node *d;
+       long hash;
+
+       spin_lock(&nfs4_deviceid_lock);
+       d = nfs4_find_get_deviceid(new->nfs_client, &new->deviceid);
+       if (d) {
+               spin_unlock(&nfs4_deviceid_lock);
+               return d;
+       }
+
+       INIT_HLIST_NODE(&new->node);
+       atomic_set(&new->ref, 1);
+       hash = nfs4_deviceid_hash(&new->deviceid);
+       hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
+       spin_unlock(&nfs4_deviceid_lock);
+
+       return new;
+}
+EXPORT_SYMBOL_GPL(nfs4_insert_deviceid_node);
+
+/*
+ * Dereference a deviceid node and delete it when its reference count drops
+ * to zero.
+ *
+ * @d deviceid node to put
+ *
+ * @ret true iff the node was deleted
+ */
+bool
+nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
+{
+       if (!atomic_dec_and_lock(&d->ref, &nfs4_deviceid_lock))
+               return false;
+       hlist_del_init_rcu(&d->node);
+       spin_unlock(&nfs4_deviceid_lock);
+       synchronize_rcu();
+       return true;
+}
+EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);