Revision 227823d2074da0c138d2abc0074b2dd281bbf923 authored by Dai Ngo on 23 January 2020, 01:45:39 UTC, committed by Anna Schumaker on 04 February 2020, 15:50:44 UTC
When the directory is large and it's being modified by one client while another client is doing the 'ls -l' on the same directory then the cache page invalidation from nfs_force_use_readdirplus causes the reading client to keep restarting READDIRPLUS from cookie 0 which causes the 'ls -l' to take a very long time to complete, possibly never completing. Currently when nfs_force_use_readdirplus is called to switch from READDIR to READDIRPLUS, it invalidates all the cached pages of the directory. This cache page invalidation causes the next nfs_readdir to re-read the directory content from cookie 0. This patch is to optimise the cache invalidation in nfs_force_use_readdirplus by only truncating the cached pages from last page index accessed to the end the file. It also marks the inode to delay invalidating all the cached page of the directory until the next initial nfs_readdir of the next 'ls' instance. Signed-off-by: Dai Ngo <dai.ngo@oracle.com> Reviewed-by: Trond Myklebust <trond.myklebust@hammerspace.com> [Anna - Fix conflicts with Trond's readdir patches] [Anna - Remove redundant call to nfs_zap_mapping()] [Anna - Replace d_inode(file_dentry(desc->file)) with file_inode(desc->file)] Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
1 parent 93a6ab7
psnap.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* SNAP data link layer. Derived from 802.2
*
* Alan Cox <alan@lxorguk.ukuu.org.uk>,
* from the 802.2 layer by Greg Page.
* Merged in additions from Greg Page's psnap.c.
*/
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/datalink.h>
#include <net/llc.h>
#include <net/psnap.h>
#include <linux/mm.h>
#include <linux/in.h>
#include <linux/init.h>
#include <linux/rculist.h>
static LIST_HEAD(snap_list);
static DEFINE_SPINLOCK(snap_lock);
static struct llc_sap *snap_sap;
/*
* Find a snap client by matching the 5 bytes.
*/
static struct datalink_proto *find_snap_client(const unsigned char *desc)
{
struct datalink_proto *proto = NULL, *p;
list_for_each_entry_rcu(p, &snap_list, node) {
if (!memcmp(p->type, desc, 5)) {
proto = p;
break;
}
}
return proto;
}
/*
* A SNAP packet has arrived
*/
static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
int rc = 1;
struct datalink_proto *proto;
static struct packet_type snap_packet_type = {
.type = cpu_to_be16(ETH_P_SNAP),
};
if (unlikely(!pskb_may_pull(skb, 5)))
goto drop;
rcu_read_lock();
proto = find_snap_client(skb_transport_header(skb));
if (proto) {
/* Pass the frame on. */
skb->transport_header += 5;
skb_pull_rcsum(skb, 5);
rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
}
rcu_read_unlock();
if (unlikely(!proto))
goto drop;
out:
return rc;
drop:
kfree_skb(skb);
goto out;
}
/*
* Put a SNAP header on a frame and pass to 802.2
*/
static int snap_request(struct datalink_proto *dl,
struct sk_buff *skb, u8 *dest)
{
memcpy(skb_push(skb, 5), dl->type, 5);
llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap);
return 0;
}
/*
* Set up the SNAP layer
*/
EXPORT_SYMBOL(register_snap_client);
EXPORT_SYMBOL(unregister_snap_client);
static const char snap_err_msg[] __initconst =
KERN_CRIT "SNAP - unable to register with 802.2\n";
static int __init snap_init(void)
{
snap_sap = llc_sap_open(0xAA, snap_rcv);
if (!snap_sap) {
printk(snap_err_msg);
return -EBUSY;
}
return 0;
}
module_init(snap_init);
static void __exit snap_exit(void)
{
llc_sap_put(snap_sap);
}
module_exit(snap_exit);
/*
* Register SNAP clients. We don't yet use this for IP.
*/
struct datalink_proto *register_snap_client(const unsigned char *desc,
int (*rcvfunc)(struct sk_buff *,
struct net_device *,
struct packet_type *,
struct net_device *))
{
struct datalink_proto *proto = NULL;
spin_lock_bh(&snap_lock);
if (find_snap_client(desc))
goto out;
proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
if (proto) {
memcpy(proto->type, desc, 5);
proto->rcvfunc = rcvfunc;
proto->header_length = 5 + 3; /* snap + 802.2 */
proto->request = snap_request;
list_add_rcu(&proto->node, &snap_list);
}
out:
spin_unlock_bh(&snap_lock);
return proto;
}
/*
* Unregister SNAP clients. Protocols no longer want to play with us ...
*/
void unregister_snap_client(struct datalink_proto *proto)
{
spin_lock_bh(&snap_lock);
list_del_rcu(&proto->node);
spin_unlock_bh(&snap_lock);
synchronize_net();
kfree(proto);
}
MODULE_LICENSE("GPL");
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