From: Andy Adamson <andros@xxxxxxxxxx>
A shared RCU device ID cache servicing multiple mounts of a single layout type
per meta data server (struct nfs_client).
Device IDs of type deviceid4 are required by all layout types, long lived and
read at each I/O. They are added to the deviceid cache at first reference by
a layout via GETDEVICEINFO and (currently) are only removed at umount.
Reference count the device ID cache for each mounted file system
in the initialize_mountpoint layoutdriver_io_operation.
Dereference the device id cache on file system in the uninitialize_mountpoint
layoutdriver_io_operation called at umount
Each layoutsegment assigns a pointer and takes a reference to the
nfs4_deviceid structure identified by the layout deviceid.
This is so that there are no deviceid lookups for the normal I/O path.
Even thought required by all layouttypes, the deviceid is not exposed in the
LAYOUTGET4res but is instead hidden in the opaque layouttype4.
Therefore, each layout type alloc_lseg calls nfs4_set_layout_deviceid,
and free_lseg calls nfs4_unset_layout_deviceid.
While the file layout driver will not cache very many deviceid's, the object
and block layout drivers could cache 100's for a large installation.
Use an hlist.
Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
---
fs/nfs/pnfs.c | 167 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/nfs4_pnfs.h | 50 +++++++++++++
include/linux/nfs_fs_sb.h | 1 +
3 files changed, 218 insertions(+), 0 deletions(-)
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 91572aa..bf906cc 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -45,6 +45,7 @@
#include <linux/nfs4.h>
#include <linux/pnfs_xdr.h>
#include <linux/nfs4_pnfs.h>
+#include <linux/rculist.h>
#include "internal.h"
#include "nfs4_fs.h"
@@ -2296,3 +2297,169 @@ struct pnfs_client_operations pnfs_ops = {
EXPORT_SYMBOL(pnfs_unregister_layoutdriver);
EXPORT_SYMBOL(pnfs_register_layoutdriver);
+
+
+/* Device ID cache. Supports one layout type per struct nfs_client */
+int
+nfs4_alloc_init_deviceid_cache(struct nfs_client *clp,
+ void (*free_callback)(struct kref *))
+{
+ struct nfs4_deviceid_cache *c;
+
+ c = kzalloc(sizeof(struct nfs4_deviceid_cache), GFP_KERNEL);
+ if (!c)
+ return -ENOMEM;
+ spin_lock(&clp->cl_lock);
+ if (clp->cl_devid_cache != NULL) {
+ kref_get(&clp->cl_devid_cache->dc_kref);
+ spin_unlock(&clp->cl_lock);
+ dprintk("%s [kref [%d]]\n", __func__,
+ atomic_read(&clp->cl_devid_cache->dc_kref.refcount));
+ kfree(c);
+ } else {
+ int i;
+
+ spin_lock_init(&c->dc_lock);
+ for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE ; i++)
+ INIT_HLIST_HEAD(&c->dc_deviceids[i]);
+ kref_init(&c->dc_kref);
+ c->dc_free_callback = free_callback;
+ clp->cl_devid_cache = c;
+ spin_unlock(&clp->cl_lock);
+ dprintk("%s [new]\n", __func__);
+ }
+ return 0;
+}
+EXPORT_SYMBOL(nfs4_alloc_init_deviceid_cache);
+
+void
+nfs4_init_deviceid_node(struct nfs4_deviceid *d)
+{
+ INIT_HLIST_NODE(&d->de_node);
+ kref_init(&d->de_kref);
+}
+EXPORT_SYMBOL(nfs4_init_deviceid_node);
+
+/* Called from layoutdriver_io_operations->alloc_lseg */
+void
+nfs4_set_layout_deviceid(struct pnfs_layout_segment *l, struct nfs4_deviceid *d)
+{
+ dprintk("%s [%d]\n", __func__, atomic_read(&d->de_kref.refcount));
+ l->deviceid = d;
+ kref_get(&d->de_kref);
+}
+EXPORT_SYMBOL(nfs4_set_layout_deviceid);
+
+/* Called from layoutdriver_io_operations->free_lseg */
+void
+nfs4_unset_layout_deviceid(struct pnfs_layout_segment *l,
+ struct nfs4_deviceid *d,
+ void (*free_callback)(struct kref *))
+{
+ dprintk("%s [%d]\n", __func__, atomic_read(&d->de_kref.refcount));
+ l->deviceid = NULL;
+ kref_put(&d->de_kref, free_callback);
+}
+EXPORT_SYMBOL(nfs4_unset_layout_deviceid);
+
+struct nfs4_deviceid *
+nfs4_find_deviceid(struct nfs4_deviceid_cache *c, struct pnfs_deviceid *id)
+{
+ struct nfs4_deviceid *d;
+ struct hlist_node *n;
+ long hash = nfs4_deviceid_hash(id);
+
+ dprintk("--> %s hash %ld\n", __func__, hash);
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(d, n, &c->dc_deviceids[hash], de_node) {
+ if (!memcmp(&d->de_id, id, NFS4_PNFS_DEVICEID4_SIZE)) {
+ rcu_read_unlock();
+ return d;
+ }
+ }
+ rcu_read_unlock();
+ return NULL;
+}
+EXPORT_SYMBOL(nfs4_find_deviceid);
+
+/*
+ * Add or kref_get a deviceid.
+ * GETDEVICEINFOs for same deviceid can race. If deviceid is found, discard new
+ */
+struct nfs4_deviceid *
+nfs4_add_deviceid(struct nfs4_deviceid_cache *c, struct nfs4_deviceid *new)
+{
+ struct nfs4_deviceid *d;
+ struct hlist_node *n;
+ long hash = nfs4_deviceid_hash(&new->de_id);
+
+ dprintk("--> %s hash %ld\n", __func__, hash);
+ spin_lock(&c->dc_lock);
+ hlist_for_each_entry_rcu(d, n, &c->dc_deviceids[hash], de_node) {
+ if (!memcmp(&d->de_id, &new->de_id, NFS4_PNFS_DEVICEID4_SIZE)) {
+ spin_unlock(&c->dc_lock);
+ dprintk("%s [discard]\n", __func__);
+ c->dc_free_callback(&new->de_kref);
+ return d;
+ }
+ }
+ hlist_add_head_rcu(&new->de_node, &c->dc_deviceids[hash]);
+ spin_unlock(&c->dc_lock);
+ dprintk("%s [new]\n", __func__);
+ return new;
+}
+EXPORT_SYMBOL(nfs4_add_deviceid);
+
+static int
+nfs4_remove_deviceid(struct nfs4_deviceid_cache *c, long hash)
+{
+ struct nfs4_deviceid *d;
+ struct hlist_node *n;
+
+ dprintk("--> %s hash %ld\n", __func__, hash);
+ spin_lock(&c->dc_lock);
+ hlist_for_each_entry_rcu(d, n, &c->dc_deviceids[hash], de_node) {
+ hlist_del_rcu(&d->de_node);
+ spin_unlock(&c->dc_lock);
+ synchronize_rcu();
+ dprintk("%s [%d]\n", __func__,
+ atomic_read(&d->de_kref.refcount));
+ kref_put(&d->de_kref, c->dc_free_callback);
+ return 1;
+ }
+ spin_unlock(&c->dc_lock);
+ return 0;
+}
+
+static void
+nfs4_free_deviceid_cache(struct kref *kref)
+{
+ struct nfs4_deviceid_cache *cache =
+ container_of(kref, struct nfs4_deviceid_cache, dc_kref);
+ int more;
+ long i;
+
+ for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE; i++) {
+ more = 1;
+ while (more)
+ more = nfs4_remove_deviceid(cache, i);
+ }
+ kfree(cache);
+}
+
+void
+nfs4_put_deviceid_cache(struct nfs_client *clp)
+{
+ struct nfs4_deviceid_cache *tmp = clp->cl_devid_cache;
+ int refcount;
+
+ dprintk("--> %s cl_devid_cache %p\n", __func__, clp->cl_devid_cache);
+ spin_lock(&clp->cl_lock);
+ refcount = atomic_read(&clp->cl_devid_cache->dc_kref.refcount);
+ if (refcount == 1)
+ clp->cl_devid_cache = NULL;
+ spin_unlock(&clp->cl_lock);
+ dprintk("%s [%d]\n", __func__, refcount);
+ kref_put(&tmp->dc_kref, nfs4_free_deviceid_cache);
+}
+EXPORT_SYMBOL(nfs4_put_deviceid_cache);
diff --git a/include/linux/nfs4_pnfs.h b/include/linux/nfs4_pnfs.h
index 3caac60..3b7aeb7 100644
--- a/include/linux/nfs4_pnfs.h
+++ b/include/linux/nfs4_pnfs.h
@@ -106,6 +106,7 @@ struct pnfs_layout_segment {
struct kref kref;
bool valid;
struct pnfs_layout_type *layout;
+ struct nfs4_deviceid *deviceid;
u8 ld_data[]; /* layout driver private data */
};
@@ -275,6 +276,55 @@ struct pnfs_devicelist {
struct pnfs_deviceid dev_id[NFS4_PNFS_GETDEVLIST_MAXNUM];
};
+/*
+ * Device ID RCU cache. A device ID is unique per client ID 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 inline u32
+nfs4_deviceid_hash(struct pnfs_deviceid *id)
+{
+ unsigned char *cptr = (unsigned char *)id->data;
+ unsigned int nbytes = NFS4_PNFS_DEVICEID4_SIZE;
+ u32 x = 0;
+
+ while (nbytes--) {
+ x *= 37;
+ x += *cptr++;
+ }
+ return x & NFS4_DEVICE_ID_HASH_MASK;
+}
+
+struct nfs4_deviceid_cache {
+ spinlock_t dc_lock;
+ struct kref dc_kref;
+ void (*dc_free_callback)(struct kref *);
+ struct hlist_head dc_deviceids[NFS4_DEVICE_ID_HASH_SIZE];
+};
+
+/* Device ID cache node */
+struct nfs4_deviceid {
+ struct hlist_node de_node;
+ struct pnfs_deviceid de_id;
+ struct kref de_kref;
+};
+
+extern int nfs4_alloc_init_deviceid_cache(struct nfs_client *,
+ void (*free_callback)(struct kref *));
+extern void nfs4_put_deviceid_cache(struct nfs_client *);
+extern void nfs4_init_deviceid_node(struct nfs4_deviceid *);
+extern struct nfs4_deviceid *nfs4_find_deviceid(struct nfs4_deviceid_cache *,
+ struct pnfs_deviceid *);
+extern struct nfs4_deviceid *nfs4_add_deviceid(struct nfs4_deviceid_cache *,
+ struct nfs4_deviceid *);
+extern void nfs4_set_layout_deviceid(struct pnfs_layout_segment *,
+ struct nfs4_deviceid *);
+extern void nfs4_unset_layout_deviceid(struct pnfs_layout_segment *,
+ struct nfs4_deviceid *,
+ void (*free_callback)(struct kref *));
+
/* pNFS client callback functions.
* These operations allow the layout driver to access pNFS client
* specific information or call pNFS client->server operations.
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 8522461..ef2e18e 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -87,6 +87,7 @@ struct nfs_client {
u32 cl_exchange_flags;
struct nfs4_session *cl_session; /* sharred session */
struct list_head cl_lo_inodes; /* Inodes having layouts */
+ struct nfs4_deviceid_cache *cl_devid_cache; /* pNFS deviceid cache */
#endif /* CONFIG_NFS_V4_1 */
#ifdef CONFIG_NFS_FSCACHE
--
1.6.6
--
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