diff options
Diffstat (limited to 'fs/fuse/control.c')
| -rw-r--r-- | fs/fuse/control.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/fs/fuse/control.c b/fs/fuse/control.c new file mode 100644 index 000000000000..a3bce3a77253 --- /dev/null +++ b/fs/fuse/control.c @@ -0,0 +1,218 @@ +/* + FUSE: Filesystem in Userspace + Copyright (C) 2001-2006 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->f_dentry->d_inode->u.generic_ip; + 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) { + struct fuse_conn *fc = fuse_ctl_file_conn_get(file); + if (!fc) + return 0; + + file->private_data=(void *)(long)atomic_read(&fc->num_waiting); + fuse_conn_put(fc); + } + size = sprintf(tmp, "%ld\n", (long)file->private_data); + return simple_read_from_buffer(buf, len, ppos, tmp, size); +} + +static const struct file_operations fuse_ctl_abort_ops = { + .open = nonseekable_open, + .write = fuse_conn_abort_write, +}; + +static const struct file_operations fuse_ctl_waiting_ops = { + .open = nonseekable_open, + .read = fuse_conn_waiting_read, +}; + +static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, + struct fuse_conn *fc, + const char *name, + int mode, int nlink, + 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_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; + inode->i_nlink = nlink; + inode->u.generic_ip = fc; + d_add(dentry, inode); + return dentry; +} + +/* + * Add a connection to the control filesystem (if it exists). Caller + * must host 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; + parent->d_inode->i_nlink++; + sprintf(name, "%llu", (unsigned long long) fc->id); + 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)) + goto err; + + return 0; + + err: + fuse_ctl_remove_conn(fc); + return -ENOMEM; +} + +/* + * Remove a connection from the control filesystem (if it exists). + * Caller must host 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->u.generic_ip = NULL; + d_drop(dentry); + dput(dentry); + } + fuse_control_sb->s_root->d_inode->i_nlink--; +} + +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 int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags, + const char *dev_name, void *raw_data, + struct vfsmount *mnt) +{ + return get_sb_single(fs_type, flags, raw_data, + fuse_ctl_fill_super, mnt); +} + +static void fuse_ctl_kill_sb(struct super_block *sb) +{ + mutex_lock(&fuse_mutex); + fuse_control_sb = NULL; + mutex_unlock(&fuse_mutex); + + kill_litter_super(sb); +} + +static struct file_system_type fuse_ctl_fs_type = { + .owner = THIS_MODULE, + .name = "fusectl", + .get_sb = fuse_ctl_get_sb, + .kill_sb = fuse_ctl_kill_sb, +}; + +int __init fuse_ctl_init(void) +{ + return register_filesystem(&fuse_ctl_fs_type); +} + +void fuse_ctl_cleanup(void) +{ + unregister_filesystem(&fuse_ctl_fs_type); +} |