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[PATCH] make /proc/mounts pollable

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Al Viro
2005-11-07 17:15:49 -05:00
committed by Linus Torvalds
parent 1abe77b0fc
commit 5addc5dd88
3 changed files with 77 additions and 15 deletions
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60
fs/proc/base.c
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@@ -70,6 +70,7 @@
#include <linux/seccomp.h>
#include <linux/cpuset.h>
#include <linux/audit.h>
#include <linux/poll.h>
#include "internal.h"
/*
@@ -660,26 +661,38 @@ static struct file_operations proc_smaps_operations = {
#endif
extern struct seq_operations mounts_op;
struct proc_mounts {
struct seq_file m;
int event;
};
static int mounts_open(struct inode *inode, struct file *file)
{
struct task_struct *task = proc_task(inode);
int ret = seq_open(file, &mounts_op);
struct namespace *namespace;
struct proc_mounts *p;
int ret = -EINVAL;
if (!ret) {
struct seq_file *m = file->private_data;
struct namespace *namespace;
task_lock(task);
namespace = task->namespace;
if (namespace)
get_namespace(namespace);
task_unlock(task);
task_lock(task);
namespace = task->namespace;
if (namespace)
get_namespace(namespace);
task_unlock(task);
if (namespace)
m->private = namespace;
else {
seq_release(inode, file);
ret = -EINVAL;
if (namespace) {
ret = -ENOMEM;
p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
if (p) {
file->private_data = &p->m;
ret = seq_open(file, &mounts_op);
if (!ret) {
p->m.private = namespace;
p->event = namespace->event;
return 0;
}
kfree(p);
}
put_namespace(namespace);
}
return ret;
}
@@ -692,11 +705,30 @@ static int mounts_release(struct inode *inode, struct file *file)
return seq_release(inode, file);
}
static unsigned mounts_poll(struct file *file, poll_table *wait)
{
struct proc_mounts *p = file->private_data;
struct namespace *ns = p->m.private;
unsigned res = 0;
poll_wait(file, &ns->poll, wait);
spin_lock(&vfsmount_lock);
if (p->event != ns->event) {
p->event = ns->event;
res = POLLERR;
}
spin_unlock(&vfsmount_lock);
return res;
}
static struct file_operations proc_mounts_operations = {
.open = mounts_open,
.read = seq_read,
.llseek = seq_lseek,
.release = mounts_release,
.poll = mounts_poll,
};
#define PROC_BLOCK_SIZE (3*1024) /* 4K page size but our output routines use some slack for overruns */