/*
* pNFS functions to call and manage layout drivers.
*
* Copyright (c) 2002 [year of first publication]
* The Regents of the University of Michigan
* All Rights Reserved
*
* Dean Hildebrand <dhildebz@umich.edu>
*
* 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 <linux/nfs_fs.h>
#include "pnfs.h"
#define NFSDBG_FACILITY NFSDBG_PNFS
/* 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)
{
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;
}
/*
* Try to set the server's pnfs module to the pnfs layout type specified by id.
* Currently only one pNFS layout driver per filesystem is supported.
*
* @id layout type. Zero (illegal layout type) indicates pNFS not in use.
*/
void
set_pnfs_layoutdriver(struct nfs_server *server, u32 id)
{
struct pnfs_layoutdriver_type *ld_type = NULL;
if (id == 0)
goto out_no_driver;
if (!(server->nfs_client->cl_exchange_flags &
(EXCHGID4_FLAG_USE_NON_PNFS | EXCHGID4_FLAG_USE_PNFS_MDS))) {
printk(KERN_ERR "%s: id %u cl_exchange_flags 0x%x\n", __func__,
id, server->nfs_client->cl_exchange_flags);
goto out_no_driver;
}
ld_type = find_pnfs_driver(id);
if (!ld_type) {
request_module("%s-%u", LAYOUT_NFSV4_1_MODULE_PREFIX, id);
ld_type = find_pnfs_driver(id);
if (!ld_type) {
dprintk("%s: No pNFS module found for %u.\n",
__func__, 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;
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);
