NFSv4.1: pnfs: full mount/umount infrastructure

Allow a module implementing a layout type to register, and
have its mount/umount routines called for filesystems that
the server declares support it.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Andy Adamson<andros@netapp.com>
Signed-off-by: Bian Naimeng <biannm@cn.fujitsu.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 86 insertions, 2 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index b483026e82aa..cf795625610e 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -32,16 +32,51 @@
 
 #define NFSDBG_FACILITY         NFSDBG_PNFS
 
-/* STUB that returns the equivalent of "no module found" */
+/* Locking:
+ *
+ * pnfs_spinlock:
+ *      protects pnfs_modules_tbl.
+ */
+static DEFINE_SPINLOCK(pnfs_spinlock);
+
+/*
+ * pnfs_modules_tbl holds all pnfs modules
+ */
+static LIST_HEAD(pnfs_modules_tbl);
+
+/* Return the registered pnfs layout driver module matching given id */
+static struct pnfs_layoutdriver_type *
+find_pnfs_driver_locked(u32 id)
+{
+        struct pnfs_layoutdriver_type *local;
+
+        list_for_each_entry(local, &pnfs_modules_tbl, pnfs_tblid)
+                if (local->id == id)
+                        goto out;
+        local = NULL;
+out:
+        dprintk("%s: Searching for id %u, found %p\n", __func__, id, local);
+        return local;
+}
+
 static struct pnfs_layoutdriver_type *
 find_pnfs_driver(u32 id)
 {
-        return NULL;
+        struct pnfs_layoutdriver_type *local;
+
+        spin_lock(&pnfs_spinlock);
+        local = find_pnfs_driver_locked(id);
+        spin_unlock(&pnfs_spinlock);
+        return local;
 }
 
 void
 unset_pnfs_layoutdriver(struct nfs_server *nfss)
 {
+        if (nfss->pnfs_curr_ld) {
+                nfss->pnfs_curr_ld->uninitialize_mountpoint(nfss);
+                module_put(nfss->pnfs_curr_ld->owner);
+        }
         nfss->pnfs_curr_ld = NULL;
 }
 
@@ -74,7 +109,18 @@ set_pnfs_layoutdriver(struct nfs_server *server, u32 id)
                         goto out_no_driver;
                 }
         }
+        if (!try_module_get(ld_type->owner)) {
+                dprintk("%s: Could not grab reference on module\n", __func__);
+                goto out_no_driver;
+        }
         server->pnfs_curr_ld = ld_type;
+        if (ld_type->initialize_mountpoint(server)) {
+                printk(KERN_ERR
+                       "%s: Error initializing mount point for layout driver %u.\n",
+                       __func__, id);
+                module_put(ld_type->owner);
+                goto out_no_driver;
+        }
         dprintk("%s: pNFS module for %u set\n", __func__, id);
         return;
 
@@ -82,3 +128,41 @@ out_no_driver:
         dprintk("%s: Using NFSv4 I/O\n", __func__);
         server->pnfs_curr_ld = NULL;
 }
+
+int
+pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
+{
+        int status = -EINVAL;
+        struct pnfs_layoutdriver_type *tmp;
+
+        if (ld_type->id == 0) {
+                printk(KERN_ERR "%s id 0 is reserved\n", __func__);
+                return status;
+        }
+
+        spin_lock(&pnfs_spinlock);
+        tmp = find_pnfs_driver_locked(ld_type->id);
+        if (!tmp) {
+                list_add(&ld_type->pnfs_tblid, &pnfs_modules_tbl);
+                status = 0;
+                dprintk("%s Registering id:%u name:%s\n", __func__, ld_type->id,
+                        ld_type->name);
+        } else {
+                printk(KERN_ERR "%s Module with id %d already loaded!\n",
+                        __func__, ld_type->id);
+        }
+        spin_unlock(&pnfs_spinlock);
+
+        return status;
+}
+EXPORT_SYMBOL_GPL(pnfs_register_layoutdriver);
+
+void
+pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
+{
+        dprintk("%s Deregistering id:%u\n", __func__, ld_type->id);
+        spin_lock(&pnfs_spinlock);
+        list_del(&ld_type->pnfs_tblid);
+        spin_unlock(&pnfs_spinlock);
+}
+EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver);