| /* |
| FUSE: Filesystem in Userspace |
| Copyright (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> |
| #include <linux/fs_context.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) { |
| if (fc->abort_err) |
| fc->aborted = true; |
| 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 = READ_ONCE(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 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) { |
| spin_lock(&fc->bg_lock); |
| fc->max_background = val; |
| fc->blocked = fc->num_background >= fc->max_background; |
| if (!fc->blocked) |
| wake_up(&fc->blocked_waitq); |
| spin_unlock(&fc->bg_lock); |
| 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 = READ_ONCE(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 val; |
| struct fuse_conn *fc; |
| struct fuse_mount *fm; |
| ssize_t ret; |
| |
| ret = fuse_conn_limit_write(file, buf, count, ppos, &val, |
| max_user_congthresh); |
| if (ret <= 0) |
| goto out; |
| fc = fuse_ctl_file_conn_get(file); |
| if (!fc) |
| goto out; |
| |
| down_read(&fc->killsb); |
| spin_lock(&fc->bg_lock); |
| fc->congestion_threshold = val; |
| |
| /* |
| * Get any fuse_mount belonging to this fuse_conn; s_bdi is |
| * shared between all of them |
| */ |
| |
| if (!list_empty(&fc->mounts)) { |
| fm = list_first_entry(&fc->mounts, struct fuse_mount, fc_entry); |
| if (fc->num_background < fc->congestion_threshold) { |
| clear_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); |
| clear_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); |
| } else { |
| set_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); |
| set_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); |
| } |
| } |
| spin_unlock(&fc->bg_lock); |
| up_read(&fc->killsb); |
| fuse_conn_put(fc); |
| out: |
| 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; |
| |
| inode = new_inode(fuse_control_sb); |
| if (!inode) { |
| dput(dentry); |
| 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(inode); |
| /* 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); |
| |
| fc->ctl_dentry[fc->ctl_ndents++] = dentry; |
| |
| 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 || fc->no_control) |
| return 0; |
| |
| parent = fuse_control_sb->s_root; |
| inc_nlink(d_inode(parent)); |
| 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 || fc->no_control) |
| return; |
| |
| for (i = fc->ctl_ndents - 1; i >= 0; i--) { |
| struct dentry *dentry = fc->ctl_dentry[i]; |
| d_inode(dentry)->i_private = NULL; |
| if (!i) { |
| /* Get rid of submounts: */ |
| d_invalidate(dentry); |
| } |
| dput(dentry); |
| } |
| drop_nlink(d_inode(fuse_control_sb->s_root)); |
| } |
| |
| static int fuse_ctl_fill_super(struct super_block *sb, struct fs_context *fsc) |
| { |
| static const 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 int fuse_ctl_get_tree(struct fs_context *fsc) |
| { |
| return get_tree_single(fsc, fuse_ctl_fill_super); |
| } |
| |
| static const struct fs_context_operations fuse_ctl_context_ops = { |
| .get_tree = fuse_ctl_get_tree, |
| }; |
| |
| static int fuse_ctl_init_fs_context(struct fs_context *fsc) |
| { |
| fsc->ops = &fuse_ctl_context_ops; |
| return 0; |
| } |
| |
| 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", |
| .init_fs_context = fuse_ctl_init_fs_context, |
| .kill_sb = fuse_ctl_kill_sb, |
| }; |
| MODULE_ALIAS_FS("fusectl"); |
| |
| int __init fuse_ctl_init(void) |
| { |
| return register_filesystem(&fuse_ctl_fs_type); |
| } |
| |
| void fuse_ctl_cleanup(void) |
| { |
| unregister_filesystem(&fuse_ctl_fs_type); |
| } |