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SUNRPC: Add a structure to track multiple transports

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In order to support multipathing/trunking we will need the ability to
track multiple transports. This patch sets up a basic structure for
doing so.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2015-02-14 20:31:59 -05:00
parent fda1bfef9e
commit 80b14d5e61
5 changed files with 552 additions and 1 deletions
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5
include/linux/sunrpc/xprt.h
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@ -197,6 +197,11 @@ struct rpc_xprt {
transport */
unsigned int bind_index; /* bind function index */
/*
* Multipath
*/
struct list_head xprt_switch;
/*
* Connection of transports
*/

69
include/linux/sunrpc/xprtmultipath.h Normal file
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@ -0,0 +1,69 @@
/*
* RPC client multipathing definitions
*
* Copyright (c) 2015, 2016, Primary Data, Inc. All rights reserved.
*
* Trond Myklebust <trond.myklebust@primarydata.com>
*/
#ifndef _NET_SUNRPC_XPRTMULTIPATH_H
#define _NET_SUNRPC_XPRTMULTIPATH_H
struct rpc_xprt_iter_ops;
struct rpc_xprt_switch {
spinlock_t xps_lock;
struct kref xps_kref;
unsigned int xps_nxprts;
struct list_head xps_xprt_list;
struct net * xps_net;
const struct rpc_xprt_iter_ops *xps_iter_ops;
struct rcu_head xps_rcu;
};
struct rpc_xprt_iter {
struct rpc_xprt_switch __rcu *xpi_xpswitch;
struct rpc_xprt * xpi_cursor;
const struct rpc_xprt_iter_ops *xpi_ops;
};
struct rpc_xprt_iter_ops {
void (*xpi_rewind)(struct rpc_xprt_iter *);
struct rpc_xprt *(*xpi_xprt)(struct rpc_xprt_iter *);
struct rpc_xprt *(*xpi_next)(struct rpc_xprt_iter *);
};
extern struct rpc_xprt_switch *xprt_switch_alloc(struct rpc_xprt *xprt,
gfp_t gfp_flags);
extern struct rpc_xprt_switch *xprt_switch_get(struct rpc_xprt_switch *xps);
extern void xprt_switch_put(struct rpc_xprt_switch *xps);
extern void rpc_xprt_switch_set_roundrobin(struct rpc_xprt_switch *xps);
extern void rpc_xprt_switch_add_xprt(struct rpc_xprt_switch *xps,
struct rpc_xprt *xprt);
extern void rpc_xprt_switch_remove_xprt(struct rpc_xprt_switch *xps,
struct rpc_xprt *xprt);
extern void xprt_iter_init(struct rpc_xprt_iter *xpi,
struct rpc_xprt_switch *xps);
extern void xprt_iter_init_listall(struct rpc_xprt_iter *xpi,
struct rpc_xprt_switch *xps);
extern void xprt_iter_destroy(struct rpc_xprt_iter *xpi);
extern struct rpc_xprt_switch *xprt_iter_xchg_switch(
struct rpc_xprt_iter *xpi,
struct rpc_xprt_switch *newswitch);
extern struct rpc_xprt *xprt_iter_xprt(struct rpc_xprt_iter *xpi);
extern struct rpc_xprt *xprt_iter_get_xprt(struct rpc_xprt_iter *xpi);
extern struct rpc_xprt *xprt_iter_get_next(struct rpc_xprt_iter *xpi);
#endif

3
net/sunrpc/Makefile
View File

@ -12,7 +12,8 @@ sunrpc-y := clnt.o xprt.o socklib.o xprtsock.o sched.o \
svc.o svcsock.o svcauth.o svcauth_unix.o \
addr.o rpcb_clnt.o timer.o xdr.o \
sunrpc_syms.o cache.o rpc_pipe.o \
svc_xprt.o
svc_xprt.o \
xprtmultipath.o
sunrpc-$(CONFIG_SUNRPC_DEBUG) += debugfs.o
sunrpc-$(CONFIG_SUNRPC_BACKCHANNEL) += backchannel_rqst.o
sunrpc-$(CONFIG_PROC_FS) += stats.o

1
net/sunrpc/xprt.c
View File

@ -1319,6 +1319,7 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net)
spin_lock_init(&xprt->bc_pa_lock);
INIT_LIST_HEAD(&xprt->bc_pa_list);
#endif /* CONFIG_SUNRPC_BACKCHANNEL */
INIT_LIST_HEAD(&xprt->xprt_switch);
xprt->last_used = jiffies;
xprt->cwnd = RPC_INITCWND;

475
net/sunrpc/xprtmultipath.c Normal file
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@ -0,0 +1,475 @@
/*
* Multipath support for RPC
*
* Copyright (c) 2015, 2016, Primary Data, Inc. All rights reserved.
*
* Trond Myklebust <trond.myklebust@primarydata.com>
*
*/
#include <linux/types.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/slab.h>
#include <asm/cmpxchg.h>
#include <linux/spinlock.h>
#include <linux/sunrpc/xprt.h>
#include <linux/sunrpc/xprtmultipath.h>
typedef struct rpc_xprt *(*xprt_switch_find_xprt_t)(struct list_head *head,
const struct rpc_xprt *cur);
static const struct rpc_xprt_iter_ops rpc_xprt_iter_singular;
static const struct rpc_xprt_iter_ops rpc_xprt_iter_roundrobin;
static const struct rpc_xprt_iter_ops rpc_xprt_iter_listall;
static void xprt_switch_add_xprt_locked(struct rpc_xprt_switch *xps,
struct rpc_xprt *xprt)
{
if (unlikely(xprt_get(xprt) == NULL))
return;
list_add_tail_rcu(&xprt->xprt_switch, &xps->xps_xprt_list);
smp_wmb();
if (xps->xps_nxprts == 0)
xps->xps_net = xprt->xprt_net;
xps->xps_nxprts++;
}
/**
* rpc_xprt_switch_add_xprt - Add a new rpc_xprt to an rpc_xprt_switch
* @xps: pointer to struct rpc_xprt_switch
* @xprt: pointer to struct rpc_xprt
*
* Adds xprt to the end of the list of struct rpc_xprt in xps.
*/
void rpc_xprt_switch_add_xprt(struct rpc_xprt_switch *xps,
struct rpc_xprt *xprt)
{
if (xprt == NULL)
return;
spin_lock(&xps->xps_lock);
if (xps->xps_net == xprt->xprt_net || xps->xps_net == NULL)
xprt_switch_add_xprt_locked(xps, xprt);
spin_unlock(&xps->xps_lock);
}
static void xprt_switch_remove_xprt_locked(struct rpc_xprt_switch *xps,
struct rpc_xprt *xprt)
{
if (unlikely(xprt == NULL))
return;
xps->xps_nxprts--;
if (xps->xps_nxprts == 0)
xps->xps_net = NULL;
smp_wmb();
list_del_rcu(&xprt->xprt_switch);
}
/**
* rpc_xprt_switch_remove_xprt - Removes an rpc_xprt from a rpc_xprt_switch
* @xps: pointer to struct rpc_xprt_switch
* @xprt: pointer to struct rpc_xprt
*
* Removes xprt from the list of struct rpc_xprt in xps.
*/
void rpc_xprt_switch_remove_xprt(struct rpc_xprt_switch *xps,
struct rpc_xprt *xprt)
{
spin_lock(&xps->xps_lock);
xprt_switch_remove_xprt_locked(xps, xprt);
spin_unlock(&xps->xps_lock);
xprt_put(xprt);
}
/**
* xprt_switch_alloc - Allocate a new struct rpc_xprt_switch
* @xprt: pointer to struct rpc_xprt
* @gfp_flags: allocation flags
*
* On success, returns an initialised struct rpc_xprt_switch, containing
* the entry xprt. Returns NULL on failure.
*/
struct rpc_xprt_switch *xprt_switch_alloc(struct rpc_xprt *xprt,
gfp_t gfp_flags)
{
struct rpc_xprt_switch *xps;
xps = kmalloc(sizeof(*xps), gfp_flags);
if (xps != NULL) {
spin_lock_init(&xps->xps_lock);
kref_init(&xps->xps_kref);
xps->xps_nxprts = 0;
INIT_LIST_HEAD(&xps->xps_xprt_list);
xps->xps_iter_ops = &rpc_xprt_iter_singular;
xprt_switch_add_xprt_locked(xps, xprt);
}
return xps;
}
static void xprt_switch_free_entries(struct rpc_xprt_switch *xps)
{
spin_lock(&xps->xps_lock);
while (!list_empty(&xps->xps_xprt_list)) {
struct rpc_xprt *xprt;
xprt = list_first_entry(&xps->xps_xprt_list,
struct rpc_xprt, xprt_switch);
xprt_switch_remove_xprt_locked(xps, xprt);
spin_unlock(&xps->xps_lock);
xprt_put(xprt);
spin_lock(&xps->xps_lock);
}
spin_unlock(&xps->xps_lock);
}
static void xprt_switch_free(struct kref *kref)
{
struct rpc_xprt_switch *xps = container_of(kref,
struct rpc_xprt_switch, xps_kref);
xprt_switch_free_entries(xps);
kfree_rcu(xps, xps_rcu);
}
/**
* xprt_switch_get - Return a reference to a rpc_xprt_switch
* @xps: pointer to struct rpc_xprt_switch
*
* Returns a reference to xps unless the refcount is already zero.
*/
struct rpc_xprt_switch *xprt_switch_get(struct rpc_xprt_switch *xps)
{
if (xps != NULL && kref_get_unless_zero(&xps->xps_kref))
return xps;
return NULL;
}
/**
* xprt_switch_put - Release a reference to a rpc_xprt_switch
* @xps: pointer to struct rpc_xprt_switch
*
* Release the reference to xps, and free it once the refcount is zero.
*/
void xprt_switch_put(struct rpc_xprt_switch *xps)
{
if (xps != NULL)
kref_put(&xps->xps_kref, xprt_switch_free);
}
/**
* rpc_xprt_switch_set_roundrobin - Set a round-robin policy on rpc_xprt_switch
* @xps: pointer to struct rpc_xprt_switch
*
* Sets a round-robin default policy for iterators acting on xps.
*/
void rpc_xprt_switch_set_roundrobin(struct rpc_xprt_switch *xps)
{
if (READ_ONCE(xps->xps_iter_ops) != &rpc_xprt_iter_roundrobin)
WRITE_ONCE(xps->xps_iter_ops, &rpc_xprt_iter_roundrobin);
}
static
const struct rpc_xprt_iter_ops *xprt_iter_ops(const struct rpc_xprt_iter *xpi)
{
if (xpi->xpi_ops != NULL)
return xpi->xpi_ops;
return rcu_dereference(xpi->xpi_xpswitch)->xps_iter_ops;
}
static
void xprt_iter_no_rewind(struct rpc_xprt_iter *xpi)
{
}
static
void xprt_iter_default_rewind(struct rpc_xprt_iter *xpi)
{
WRITE_ONCE(xpi->xpi_cursor, NULL);
}
static
struct rpc_xprt *xprt_switch_find_first_entry(struct list_head *head)
{
return list_first_or_null_rcu(head, struct rpc_xprt, xprt_switch);
}
static
struct rpc_xprt *xprt_iter_first_entry(struct rpc_xprt_iter *xpi)
{
struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);
if (xps == NULL)
return NULL;
return xprt_switch_find_first_entry(&xps->xps_xprt_list);
}
static
struct rpc_xprt *xprt_switch_find_current_entry(struct list_head *head,
const struct rpc_xprt *cur)
{
struct rpc_xprt *pos;
list_for_each_entry_rcu(pos, head, xprt_switch) {
if (cur == pos)
return pos;
}
return NULL;
}
static
struct rpc_xprt *xprt_iter_current_entry(struct rpc_xprt_iter *xpi)
{
struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);
struct list_head *head;
if (xps == NULL)
return NULL;
head = &xps->xps_xprt_list;
if (xpi->xpi_cursor == NULL || xps->xps_nxprts < 2)
return xprt_switch_find_first_entry(head);
return xprt_switch_find_current_entry(head, xpi->xpi_cursor);
}
static
struct rpc_xprt *xprt_switch_find_next_entry(struct list_head *head,
const struct rpc_xprt *cur)
{
struct rpc_xprt *pos, *prev = NULL;
list_for_each_entry_rcu(pos, head, xprt_switch) {
if (cur == prev)
return pos;
prev = pos;
}
return NULL;
}
static
struct rpc_xprt *xprt_switch_set_next_cursor(struct list_head *head,
struct rpc_xprt **cursor,
xprt_switch_find_xprt_t find_next)
{
struct rpc_xprt *cur, *pos, *old;
cur = READ_ONCE(*cursor);
for (;;) {
old = cur;
pos = find_next(head, old);
if (pos == NULL)
break;
cur = cmpxchg_relaxed(cursor, old, pos);
if (cur == old)
break;
}
return pos;
}
static
struct rpc_xprt *xprt_iter_next_entry_multiple(struct rpc_xprt_iter *xpi,
xprt_switch_find_xprt_t find_next)
{
struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);
struct list_head *head;
if (xps == NULL)
return NULL;
head = &xps->xps_xprt_list;
if (xps->xps_nxprts < 2)
return xprt_switch_find_first_entry(head);
return xprt_switch_set_next_cursor(head, &xpi->xpi_cursor, find_next);
}
static
struct rpc_xprt *xprt_switch_find_next_entry_roundrobin(struct list_head *head,
const struct rpc_xprt *cur)
{
struct rpc_xprt *ret;
ret = xprt_switch_find_next_entry(head, cur);
if (ret != NULL)
return ret;
return xprt_switch_find_first_entry(head);
}
static
struct rpc_xprt *xprt_iter_next_entry_roundrobin(struct rpc_xprt_iter *xpi)
{
return xprt_iter_next_entry_multiple(xpi,
xprt_switch_find_next_entry_roundrobin);
}
static
struct rpc_xprt *xprt_iter_next_entry_all(struct rpc_xprt_iter *xpi)
{
return xprt_iter_next_entry_multiple(xpi, xprt_switch_find_next_entry);
}
/*
* xprt_iter_rewind - Resets the xprt iterator
* @xpi: pointer to rpc_xprt_iter
*
* Resets xpi to ensure that it points to the first entry in the list
* of transports.
*/
static
void xprt_iter_rewind(struct rpc_xprt_iter *xpi)
{
rcu_read_lock();
xprt_iter_ops(xpi)->xpi_rewind(xpi);
rcu_read_unlock();
}
static void __xprt_iter_init(struct rpc_xprt_iter *xpi,
struct rpc_xprt_switch *xps,
const struct rpc_xprt_iter_ops *ops)
{
rcu_assign_pointer(xpi->xpi_xpswitch, xprt_switch_get(xps));
xpi->xpi_cursor = NULL;
xpi->xpi_ops = ops;
}
/**
* xprt_iter_init - Initialise an xprt iterator
* @xpi: pointer to rpc_xprt_iter
* @xps: pointer to rpc_xprt_switch
*
* Initialises the iterator to use the default iterator ops
* as set in xps. This function is mainly intended for internal
* use in the rpc_client.
*/
void xprt_iter_init(struct rpc_xprt_iter *xpi,
struct rpc_xprt_switch *xps)
{
__xprt_iter_init(xpi, xps, NULL);
}
/**
* xprt_iter_init_listall - Initialise an xprt iterator
* @xpi: pointer to rpc_xprt_iter
* @xps: pointer to rpc_xprt_switch
*
* Initialises the iterator to iterate once through the entire list
* of entries in xps.
*/
void xprt_iter_init_listall(struct rpc_xprt_iter *xpi,
struct rpc_xprt_switch *xps)
{
__xprt_iter_init(xpi, xps, &rpc_xprt_iter_listall);
}
/**
* xprt_iter_xchg_switch - Atomically swap out the rpc_xprt_switch
* @xpi: pointer to rpc_xprt_iter
* @xps: pointer to a new rpc_xprt_switch or NULL
*
* Swaps out the existing xpi->xpi_xpswitch with a new value.
*/
struct rpc_xprt_switch *xprt_iter_xchg_switch(struct rpc_xprt_iter *xpi,
struct rpc_xprt_switch *newswitch)
{
struct rpc_xprt_switch __rcu *oldswitch;
/* Atomically swap out the old xpswitch */
oldswitch = xchg(&xpi->xpi_xpswitch, RCU_INITIALIZER(newswitch));
if (newswitch != NULL)
xprt_iter_rewind(xpi);
return rcu_dereference_protected(oldswitch, true);
}
/**
* xprt_iter_destroy - Destroys the xprt iterator
* @xpi pointer to rpc_xprt_iter
*/
void xprt_iter_destroy(struct rpc_xprt_iter *xpi)
{
xprt_switch_put(xprt_iter_xchg_switch(xpi, NULL));
}
/**
* xprt_iter_xprt - Returns the rpc_xprt pointed to by the cursor
* @xpi: pointer to rpc_xprt_iter
*
* Returns a pointer to the struct rpc_xprt that is currently
* pointed to by the cursor.
* Caller must be holding rcu_read_lock().
*/
struct rpc_xprt *xprt_iter_xprt(struct rpc_xprt_iter *xpi)
{
WARN_ON_ONCE(!rcu_read_lock_held());
return xprt_iter_ops(xpi)->xpi_xprt(xpi);
}
static
struct rpc_xprt *xprt_iter_get_helper(struct rpc_xprt_iter *xpi,
struct rpc_xprt *(*fn)(struct rpc_xprt_iter *))
{
struct rpc_xprt *ret;
do {
ret = fn(xpi);
if (ret == NULL)
break;
ret = xprt_get(ret);
} while (ret == NULL);
return ret;
}
/**
* xprt_iter_get_xprt - Returns the rpc_xprt pointed to by the cursor
* @xpi: pointer to rpc_xprt_iter
*
* Returns a reference to the struct rpc_xprt that is currently
* pointed to by the cursor.
*/
struct rpc_xprt *xprt_iter_get_xprt(struct rpc_xprt_iter *xpi)
{
struct rpc_xprt *xprt;
rcu_read_lock();
xprt = xprt_iter_get_helper(xpi, xprt_iter_ops(xpi)->xpi_xprt);
rcu_read_unlock();
return xprt;
}
/**
* xprt_iter_get_next - Returns the next rpc_xprt following the cursor
* @xpi: pointer to rpc_xprt_iter
*
* Returns a reference to the struct rpc_xprt that immediately follows the
* entry pointed to by the cursor.
*/
struct rpc_xprt *xprt_iter_get_next(struct rpc_xprt_iter *xpi)
{
struct rpc_xprt *xprt;
rcu_read_lock();
xprt = xprt_iter_get_helper(xpi, xprt_iter_ops(xpi)->xpi_next);
rcu_read_unlock();
return xprt;
}
/* Policy for always returning the first entry in the rpc_xprt_switch */
static
const struct rpc_xprt_iter_ops rpc_xprt_iter_singular = {
.xpi_rewind = xprt_iter_no_rewind,
.xpi_xprt = xprt_iter_first_entry,
.xpi_next = xprt_iter_first_entry,
};
/* Policy for round-robin iteration of entries in the rpc_xprt_switch */
static
const struct rpc_xprt_iter_ops rpc_xprt_iter_roundrobin = {
.xpi_rewind = xprt_iter_default_rewind,
.xpi_xprt = xprt_iter_current_entry,
.xpi_next = xprt_iter_next_entry_roundrobin,
};
/* Policy for once-through iteration of entries in the rpc_xprt_switch */
static
const struct rpc_xprt_iter_ops rpc_xprt_iter_listall = {
.xpi_rewind = xprt_iter_default_rewind,
.xpi_xprt = xprt_iter_current_entry,
.xpi_next = xprt_iter_next_entry_all,
};