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linux-next/fs/nfs/pnfs.c
Benny Halevy e5e940170b NFS: create and destroy inode's layout cache
At the start of the io paths, try to grab the relevant layout
information.  This will initiate the inode's layout cache, but
stubs ensure the cache stays empty.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Dean Hildebrand <dhildebz@umich.edu>
Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Tao Guo <guotao@nrchpc.ac.cn>
Signed-off-by: Ricardo Labiaga <ricardo.labiaga@netapp.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2010-10-24 18:07:10 -04:00

309 lines
7.9 KiB
C

/*
* 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);
static void
get_layout_hdr_locked(struct pnfs_layout_hdr *lo)
{
assert_spin_locked(&lo->inode->i_lock);
lo->refcount++;
}
static void
put_layout_hdr_locked(struct pnfs_layout_hdr *lo)
{
assert_spin_locked(&lo->inode->i_lock);
BUG_ON(lo->refcount == 0);
lo->refcount--;
if (!lo->refcount) {
dprintk("%s: freeing layout cache %p\n", __func__, lo);
NFS_I(lo->inode)->layout = NULL;
kfree(lo);
}
}
void
pnfs_destroy_layout(struct nfs_inode *nfsi)
{
struct pnfs_layout_hdr *lo;
spin_lock(&nfsi->vfs_inode.i_lock);
lo = nfsi->layout;
if (lo) {
/* Matched by refcount set to 1 in alloc_init_layout_hdr */
put_layout_hdr_locked(lo);
}
spin_unlock(&nfsi->vfs_inode.i_lock);
}
/* STUB - pretend LAYOUTGET to server failed */
static struct pnfs_layout_segment *
send_layoutget(struct pnfs_layout_hdr *lo,
struct nfs_open_context *ctx,
u32 iomode)
{
struct inode *ino = lo->inode;
set_bit(lo_fail_bit(iomode), &lo->state);
spin_lock(&ino->i_lock);
put_layout_hdr_locked(lo);
spin_unlock(&ino->i_lock);
return NULL;
}
static struct pnfs_layout_hdr *
alloc_init_layout_hdr(struct inode *ino)
{
struct pnfs_layout_hdr *lo;
lo = kzalloc(sizeof(struct pnfs_layout_hdr), GFP_KERNEL);
if (!lo)
return NULL;
lo->refcount = 1;
lo->inode = ino;
return lo;
}
static struct pnfs_layout_hdr *
pnfs_find_alloc_layout(struct inode *ino)
{
struct nfs_inode *nfsi = NFS_I(ino);
struct pnfs_layout_hdr *new = NULL;
dprintk("%s Begin ino=%p layout=%p\n", __func__, ino, nfsi->layout);
assert_spin_locked(&ino->i_lock);
if (nfsi->layout)
return nfsi->layout;
spin_unlock(&ino->i_lock);
new = alloc_init_layout_hdr(ino);
spin_lock(&ino->i_lock);
if (likely(nfsi->layout == NULL)) /* Won the race? */
nfsi->layout = new;
else
kfree(new);
return nfsi->layout;
}
/* STUB - LAYOUTGET never succeeds, so cache is empty */
static struct pnfs_layout_segment *
pnfs_has_layout(struct pnfs_layout_hdr *lo, u32 iomode)
{
return NULL;
}
/*
* Layout segment is retreived from the server if not cached.
* The appropriate layout segment is referenced and returned to the caller.
*/
struct pnfs_layout_segment *
pnfs_update_layout(struct inode *ino,
struct nfs_open_context *ctx,
enum pnfs_iomode iomode)
{
struct nfs_inode *nfsi = NFS_I(ino);
struct pnfs_layout_hdr *lo;
struct pnfs_layout_segment *lseg = NULL;
if (!pnfs_enabled_sb(NFS_SERVER(ino)))
return NULL;
spin_lock(&ino->i_lock);
lo = pnfs_find_alloc_layout(ino);
if (lo == NULL) {
dprintk("%s ERROR: can't get pnfs_layout_hdr\n", __func__);
goto out_unlock;
}
/* Check to see if the layout for the given range already exists */
lseg = pnfs_has_layout(lo, iomode);
if (lseg) {
dprintk("%s: Using cached lseg %p for iomode %d)\n",
__func__, lseg, iomode);
goto out_unlock;
}
/* if LAYOUTGET already failed once we don't try again */
if (test_bit(lo_fail_bit(iomode), &nfsi->layout->state))
goto out_unlock;
get_layout_hdr_locked(lo);
spin_unlock(&ino->i_lock);
lseg = send_layoutget(lo, ctx, iomode);
out:
dprintk("%s end, state 0x%lx lseg %p\n", __func__,
nfsi->layout->state, lseg);
return lseg;
out_unlock:
spin_unlock(&ino->i_lock);
goto out;
}