From d68e3c4aa416d592d79152a49af121e4ecb204e3 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 12 Sep 2014 16:40:20 -0400 Subject: [PATCH] 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 --- fs/lockd/Makefile | 1 + fs/lockd/procfs.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++ fs/lockd/procfs.h | 28 +++++++++++++++ fs/lockd/svc.c | 9 +++++ 4 files changed, 130 insertions(+) create mode 100644 fs/lockd/procfs.c create mode 100644 fs/lockd/procfs.h diff --git a/fs/lockd/Makefile b/fs/lockd/Makefile index 6a0b351ce30e..9b320cc2a8cf 100644 --- a/fs/lockd/Makefile +++ b/fs/lockd/Makefile @@ -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) diff --git a/fs/lockd/procfs.c b/fs/lockd/procfs.c new file mode 100644 index 000000000000..2a0a98480e39 --- /dev/null +++ b/fs/lockd/procfs.c @@ -0,0 +1,92 @@ +/* + * Procfs support for lockd + * + * Copyright (c) 2014 Jeff Layton + */ + +#include +#include +#include +#include +#include + +#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); +} diff --git a/fs/lockd/procfs.h b/fs/lockd/procfs.h new file mode 100644 index 000000000000..2257a1311027 --- /dev/null +++ b/fs/lockd/procfs.h @@ -0,0 +1,28 @@ +/* + * Procfs support for lockd + * + * Copyright (c) 2014 Jeff Layton + */ +#ifndef _LOCKD_PROCFS_H +#define _LOCKD_PROCFS_H + +#include + +#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 */ diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index 266b67972305..8146cfe97d8d 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -36,6 +36,7 @@ #include #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); -- 2.30.2