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