lockd: add a /proc/fs/lockd/nlm_end_grace file

Add a new procfile that will allow a (privileged) userland process to
end the NLM grace period early. The basic idea here will be to have
sm-notify write to this file, if it sent out no NOTIFY requests when
it runs. In that situation, we can generally expect that there will be
no reclaim requests so the grace period can be lifted early.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
This commit is contained in:
Jeff Layton 2014-09-12 16:40:20 -04:00 committed by J. Bruce Fields
parent 3b3e7b7223
commit d68e3c4aa4
4 changed files with 130 additions and 0 deletions

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@ -7,4 +7,5 @@ obj-$(CONFIG_LOCKD) += lockd.o
lockd-objs-y := clntlock.o clntproc.o clntxdr.o host.o svc.o svclock.o \
svcshare.o svcproc.o svcsubs.o mon.o xdr.o
lockd-objs-$(CONFIG_LOCKD_V4) += clnt4xdr.o xdr4.o svc4proc.o
lockd-objs-$(CONFIG_PROC_FS) += procfs.o
lockd-objs := $(lockd-objs-y)

92
fs/lockd/procfs.c Normal file
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@ -0,0 +1,92 @@
/*
* Procfs support for lockd
*
* Copyright (c) 2014 Jeff Layton <jlayton@primarydata.com>
*/
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/nsproxy.h>
#include <net/net_namespace.h>
#include "netns.h"
#include "procfs.h"
/*
* We only allow strings that start with 'Y', 'y', or '1'.
*/
static ssize_t
nlm_end_grace_write(struct file *file, const char __user *buf, size_t size,
loff_t *pos)
{
char *data;
struct lockd_net *ln = net_generic(current->nsproxy->net_ns,
lockd_net_id);
if (size < 1)
return -EINVAL;
data = simple_transaction_get(file, buf, size);
if (IS_ERR(data))
return PTR_ERR(data);
switch(data[0]) {
case 'Y':
case 'y':
case '1':
locks_end_grace(&ln->lockd_manager);
break;
default:
return -EINVAL;
}
return size;
}
static ssize_t
nlm_end_grace_read(struct file *file, char __user *buf, size_t size,
loff_t *pos)
{
struct lockd_net *ln = net_generic(current->nsproxy->net_ns,
lockd_net_id);
char resp[3];
resp[0] = list_empty(&ln->lockd_manager.list) ? 'Y' : 'N';
resp[1] = '\n';
resp[2] = '\0';
return simple_read_from_buffer(buf, size, pos, resp, sizeof(resp));
}
static const struct file_operations lockd_end_grace_operations = {
.write = nlm_end_grace_write,
.read = nlm_end_grace_read,
.llseek = default_llseek,
.release = simple_transaction_release,
.owner = THIS_MODULE,
};
int __init
lockd_create_procfs(void)
{
struct proc_dir_entry *entry;
entry = proc_mkdir("fs/lockd", NULL);
if (!entry)
return -ENOMEM;
entry = proc_create("nlm_end_grace", S_IRUGO|S_IWUSR, entry,
&lockd_end_grace_operations);
if (!entry) {
remove_proc_entry("fs/lockd", NULL);
return -ENOMEM;
}
return 0;
}
void __exit
lockd_remove_procfs(void)
{
remove_proc_entry("fs/lockd/nlm_end_grace", NULL);
remove_proc_entry("fs/lockd", NULL);
}

28
fs/lockd/procfs.h Normal file
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@ -0,0 +1,28 @@
/*
* Procfs support for lockd
*
* Copyright (c) 2014 Jeff Layton <jlayton@primarydata.com>
*/
#ifndef _LOCKD_PROCFS_H
#define _LOCKD_PROCFS_H
#include <linux/kconfig.h>
#if IS_ENABLED(CONFIG_PROC_FS)
int lockd_create_procfs(void);
void lockd_remove_procfs(void);
#else
static inline int
lockd_create_procfs(void)
{
return 0;
}
static inline void
lockd_remove_procfs(void)
{
return;
}
#endif /* IS_ENABLED(CONFIG_PROC_FS) */
#endif /* _LOCKD_PROCFS_H */

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@ -36,6 +36,7 @@
#include <linux/nfs.h>
#include "netns.h"
#include "procfs.h"
#define NLMDBG_FACILITY NLMDBG_SVC
#define LOCKD_BUFSIZE (1024 + NLMSVC_XDRSIZE)
@ -620,8 +621,15 @@ static int __init init_nlm(void)
err = register_pernet_subsys(&lockd_net_ops);
if (err)
goto err_pernet;
err = lockd_create_procfs();
if (err)
goto err_procfs;
return 0;
err_procfs:
unregister_pernet_subsys(&lockd_net_ops);
err_pernet:
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(nlm_sysctl_table);
@ -634,6 +642,7 @@ static void __exit exit_nlm(void)
{
/* FIXME: delete all NLM clients */
nlm_shutdown_hosts();
lockd_remove_procfs();
unregister_pernet_subsys(&lockd_net_ops);
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(nlm_sysctl_table);