362 lines
8.0 KiB
C
362 lines
8.0 KiB
C
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/*
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FUSE: Filesystem in Userspace
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Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
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This program can be distributed under the terms of the GNU GPL.
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See the file COPYING.
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*/
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#include "fuse_i.h"
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#include <linux/init.h>
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#include <linux/module.h>
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#define FUSE_CTL_SUPER_MAGIC 0x65735543
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/*
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* This is non-NULL when the single instance of the control filesystem
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* exists. Protected by fuse_mutex
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*/
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static struct super_block *fuse_control_sb;
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static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
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{
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struct fuse_conn *fc;
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mutex_lock(&fuse_mutex);
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fc = file_inode(file)->i_private;
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if (fc)
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fc = fuse_conn_get(fc);
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mutex_unlock(&fuse_mutex);
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return fc;
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}
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static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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if (fc) {
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fuse_abort_conn(fc);
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fuse_conn_put(fc);
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}
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return count;
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}
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static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
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size_t len, loff_t *ppos)
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{
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char tmp[32];
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size_t size;
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if (!*ppos) {
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long value;
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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if (!fc)
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return 0;
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value = atomic_read(&fc->num_waiting);
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file->private_data = (void *)value;
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fuse_conn_put(fc);
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}
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size = sprintf(tmp, "%ld\n", (long)file->private_data);
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return simple_read_from_buffer(buf, len, ppos, tmp, size);
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}
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static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf,
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size_t len, loff_t *ppos, unsigned val)
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{
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char tmp[32];
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size_t size = sprintf(tmp, "%u\n", val);
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return simple_read_from_buffer(buf, len, ppos, tmp, size);
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}
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static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos, unsigned *val,
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unsigned global_limit)
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{
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unsigned long t;
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unsigned limit = (1 << 16) - 1;
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int err;
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if (*ppos)
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return -EINVAL;
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err = kstrtoul_from_user(buf, count, 0, &t);
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if (err)
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return err;
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if (!capable(CAP_SYS_ADMIN))
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limit = min(limit, global_limit);
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if (t > limit)
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return -EINVAL;
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*val = t;
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return count;
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}
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static ssize_t fuse_conn_max_background_read(struct file *file,
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char __user *buf, size_t len,
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loff_t *ppos)
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{
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struct fuse_conn *fc;
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unsigned val;
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fc = fuse_ctl_file_conn_get(file);
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if (!fc)
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return 0;
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val = READ_ONCE(fc->max_background);
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fuse_conn_put(fc);
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return fuse_conn_limit_read(file, buf, len, ppos, val);
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}
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static ssize_t fuse_conn_max_background_write(struct file *file,
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const char __user *buf,
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size_t count, loff_t *ppos)
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{
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unsigned uninitialized_var(val);
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ssize_t ret;
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ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
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max_user_bgreq);
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if (ret > 0) {
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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if (fc) {
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fc->max_background = val;
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fuse_conn_put(fc);
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}
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}
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return ret;
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}
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static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
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char __user *buf, size_t len,
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loff_t *ppos)
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{
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struct fuse_conn *fc;
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unsigned val;
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fc = fuse_ctl_file_conn_get(file);
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if (!fc)
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return 0;
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val = READ_ONCE(fc->congestion_threshold);
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fuse_conn_put(fc);
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return fuse_conn_limit_read(file, buf, len, ppos, val);
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}
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static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
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const char __user *buf,
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size_t count, loff_t *ppos)
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{
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unsigned uninitialized_var(val);
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ssize_t ret;
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ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
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max_user_congthresh);
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if (ret > 0) {
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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if (fc) {
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fc->congestion_threshold = val;
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fuse_conn_put(fc);
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}
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}
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return ret;
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}
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static const struct file_operations fuse_ctl_abort_ops = {
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.open = nonseekable_open,
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.write = fuse_conn_abort_write,
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.llseek = no_llseek,
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};
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static const struct file_operations fuse_ctl_waiting_ops = {
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.open = nonseekable_open,
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.read = fuse_conn_waiting_read,
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.llseek = no_llseek,
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};
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static const struct file_operations fuse_conn_max_background_ops = {
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.open = nonseekable_open,
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.read = fuse_conn_max_background_read,
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.write = fuse_conn_max_background_write,
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.llseek = no_llseek,
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};
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static const struct file_operations fuse_conn_congestion_threshold_ops = {
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.open = nonseekable_open,
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.read = fuse_conn_congestion_threshold_read,
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.write = fuse_conn_congestion_threshold_write,
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.llseek = no_llseek,
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};
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static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
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struct fuse_conn *fc,
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const char *name,
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int mode, int nlink,
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const struct inode_operations *iop,
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const struct file_operations *fop)
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{
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struct dentry *dentry;
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struct inode *inode;
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BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
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dentry = d_alloc_name(parent, name);
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if (!dentry)
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return NULL;
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inode = new_inode(fuse_control_sb);
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if (!inode) {
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dput(dentry);
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return NULL;
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}
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inode->i_ino = get_next_ino();
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inode->i_mode = mode;
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inode->i_uid = fc->user_id;
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inode->i_gid = fc->group_id;
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inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
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/* setting ->i_op to NULL is not allowed */
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if (iop)
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inode->i_op = iop;
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inode->i_fop = fop;
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set_nlink(inode, nlink);
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inode->i_private = fc;
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d_add(dentry, inode);
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fc->ctl_dentry[fc->ctl_ndents++] = dentry;
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return dentry;
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}
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/*
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* Add a connection to the control filesystem (if it exists). Caller
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* must hold fuse_mutex
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*/
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int fuse_ctl_add_conn(struct fuse_conn *fc)
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{
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struct dentry *parent;
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char name[32];
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if (!fuse_control_sb)
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return 0;
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parent = fuse_control_sb->s_root;
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inc_nlink(d_inode(parent));
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sprintf(name, "%u", fc->dev);
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parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
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&simple_dir_inode_operations,
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&simple_dir_operations);
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if (!parent)
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goto err;
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if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
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NULL, &fuse_ctl_waiting_ops) ||
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!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
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NULL, &fuse_ctl_abort_ops) ||
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!fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
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1, NULL, &fuse_conn_max_background_ops) ||
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!fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
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S_IFREG | 0600, 1, NULL,
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&fuse_conn_congestion_threshold_ops))
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goto err;
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return 0;
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err:
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fuse_ctl_remove_conn(fc);
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return -ENOMEM;
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}
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/*
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* Remove a connection from the control filesystem (if it exists).
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* Caller must hold fuse_mutex
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*/
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void fuse_ctl_remove_conn(struct fuse_conn *fc)
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{
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int i;
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if (!fuse_control_sb)
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return;
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for (i = fc->ctl_ndents - 1; i >= 0; i--) {
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struct dentry *dentry = fc->ctl_dentry[i];
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d_inode(dentry)->i_private = NULL;
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if (!i) {
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/* Get rid of submounts: */
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d_invalidate(dentry);
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}
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dput(dentry);
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}
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drop_nlink(d_inode(fuse_control_sb->s_root));
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}
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static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
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{
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struct tree_descr empty_descr = {""};
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struct fuse_conn *fc;
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int err;
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err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
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if (err)
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return err;
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mutex_lock(&fuse_mutex);
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BUG_ON(fuse_control_sb);
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fuse_control_sb = sb;
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list_for_each_entry(fc, &fuse_conn_list, entry) {
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err = fuse_ctl_add_conn(fc);
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if (err) {
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fuse_control_sb = NULL;
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mutex_unlock(&fuse_mutex);
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return err;
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}
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}
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mutex_unlock(&fuse_mutex);
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return 0;
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}
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static struct dentry *fuse_ctl_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *raw_data)
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{
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return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
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}
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static void fuse_ctl_kill_sb(struct super_block *sb)
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{
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struct fuse_conn *fc;
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mutex_lock(&fuse_mutex);
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fuse_control_sb = NULL;
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list_for_each_entry(fc, &fuse_conn_list, entry)
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fc->ctl_ndents = 0;
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mutex_unlock(&fuse_mutex);
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kill_litter_super(sb);
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}
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static struct file_system_type fuse_ctl_fs_type = {
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.owner = THIS_MODULE,
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.name = "fusectl",
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.mount = fuse_ctl_mount,
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.kill_sb = fuse_ctl_kill_sb,
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};
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MODULE_ALIAS_FS("fusectl");
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int __init fuse_ctl_init(void)
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{
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return register_filesystem(&fuse_ctl_fs_type);
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}
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void __exit fuse_ctl_cleanup(void)
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{
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unregister_filesystem(&fuse_ctl_fs_type);
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}
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