1 /* 2 FUSE: Filesystem in Userspace 3 Copyright (C) 2001-2006 Miklos Szeredi <miklos@szeredi.hu> 4 5 This program can be distributed under the terms of the GNU GPL. 6 See the file COPYING. 7 */ 8 9 #include "fuse_i.h" 10 11 #include <linux/init.h> 12 #include <linux/module.h> 13 14 #define FUSE_CTL_SUPER_MAGIC 0x65735543 15 16 /* 17 * This is non-NULL when the single instance of the control filesystem 18 * exists. Protected by fuse_mutex 19 */ 20 static struct super_block *fuse_control_sb; 21 22 static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file) 23 { 24 struct fuse_conn *fc; 25 mutex_lock(&fuse_mutex); 26 fc = file->f_path.dentry->d_inode->i_private; 27 if (fc) 28 fc = fuse_conn_get(fc); 29 mutex_unlock(&fuse_mutex); 30 return fc; 31 } 32 33 static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf, 34 size_t count, loff_t *ppos) 35 { 36 struct fuse_conn *fc = fuse_ctl_file_conn_get(file); 37 if (fc) { 38 fuse_abort_conn(fc); 39 fuse_conn_put(fc); 40 } 41 return count; 42 } 43 44 static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf, 45 size_t len, loff_t *ppos) 46 { 47 char tmp[32]; 48 size_t size; 49 50 if (!*ppos) { 51 struct fuse_conn *fc = fuse_ctl_file_conn_get(file); 52 if (!fc) 53 return 0; 54 55 file->private_data=(void *)(long)atomic_read(&fc->num_waiting); 56 fuse_conn_put(fc); 57 } 58 size = sprintf(tmp, "%ld\n", (long)file->private_data); 59 return simple_read_from_buffer(buf, len, ppos, tmp, size); 60 } 61 62 static const struct file_operations fuse_ctl_abort_ops = { 63 .open = nonseekable_open, 64 .write = fuse_conn_abort_write, 65 }; 66 67 static const struct file_operations fuse_ctl_waiting_ops = { 68 .open = nonseekable_open, 69 .read = fuse_conn_waiting_read, 70 }; 71 72 static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, 73 struct fuse_conn *fc, 74 const char *name, 75 int mode, int nlink, 76 const struct inode_operations *iop, 77 const struct file_operations *fop) 78 { 79 struct dentry *dentry; 80 struct inode *inode; 81 82 BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES); 83 dentry = d_alloc_name(parent, name); 84 if (!dentry) 85 return NULL; 86 87 fc->ctl_dentry[fc->ctl_ndents++] = dentry; 88 inode = new_inode(fuse_control_sb); 89 if (!inode) 90 return NULL; 91 92 inode->i_mode = mode; 93 inode->i_uid = fc->user_id; 94 inode->i_gid = fc->group_id; 95 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 96 /* setting ->i_op to NULL is not allowed */ 97 if (iop) 98 inode->i_op = iop; 99 inode->i_fop = fop; 100 inode->i_nlink = nlink; 101 inode->i_private = fc; 102 d_add(dentry, inode); 103 return dentry; 104 } 105 106 /* 107 * Add a connection to the control filesystem (if it exists). Caller 108 * must hold fuse_mutex 109 */ 110 int fuse_ctl_add_conn(struct fuse_conn *fc) 111 { 112 struct dentry *parent; 113 char name[32]; 114 115 if (!fuse_control_sb) 116 return 0; 117 118 parent = fuse_control_sb->s_root; 119 inc_nlink(parent->d_inode); 120 sprintf(name, "%u", fc->dev); 121 parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2, 122 &simple_dir_inode_operations, 123 &simple_dir_operations); 124 if (!parent) 125 goto err; 126 127 if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1, 128 NULL, &fuse_ctl_waiting_ops) || 129 !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1, 130 NULL, &fuse_ctl_abort_ops)) 131 goto err; 132 133 return 0; 134 135 err: 136 fuse_ctl_remove_conn(fc); 137 return -ENOMEM; 138 } 139 140 /* 141 * Remove a connection from the control filesystem (if it exists). 142 * Caller must hold fuse_mutex 143 */ 144 void fuse_ctl_remove_conn(struct fuse_conn *fc) 145 { 146 int i; 147 148 if (!fuse_control_sb) 149 return; 150 151 for (i = fc->ctl_ndents - 1; i >= 0; i--) { 152 struct dentry *dentry = fc->ctl_dentry[i]; 153 dentry->d_inode->i_private = NULL; 154 d_drop(dentry); 155 dput(dentry); 156 } 157 fuse_control_sb->s_root->d_inode->i_nlink--; 158 } 159 160 static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent) 161 { 162 struct tree_descr empty_descr = {""}; 163 struct fuse_conn *fc; 164 int err; 165 166 err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr); 167 if (err) 168 return err; 169 170 mutex_lock(&fuse_mutex); 171 BUG_ON(fuse_control_sb); 172 fuse_control_sb = sb; 173 list_for_each_entry(fc, &fuse_conn_list, entry) { 174 err = fuse_ctl_add_conn(fc); 175 if (err) { 176 fuse_control_sb = NULL; 177 mutex_unlock(&fuse_mutex); 178 return err; 179 } 180 } 181 mutex_unlock(&fuse_mutex); 182 183 return 0; 184 } 185 186 static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags, 187 const char *dev_name, void *raw_data, 188 struct vfsmount *mnt) 189 { 190 return get_sb_single(fs_type, flags, raw_data, 191 fuse_ctl_fill_super, mnt); 192 } 193 194 static void fuse_ctl_kill_sb(struct super_block *sb) 195 { 196 struct fuse_conn *fc; 197 198 mutex_lock(&fuse_mutex); 199 fuse_control_sb = NULL; 200 list_for_each_entry(fc, &fuse_conn_list, entry) 201 fc->ctl_ndents = 0; 202 mutex_unlock(&fuse_mutex); 203 204 kill_litter_super(sb); 205 } 206 207 static struct file_system_type fuse_ctl_fs_type = { 208 .owner = THIS_MODULE, 209 .name = "fusectl", 210 .get_sb = fuse_ctl_get_sb, 211 .kill_sb = fuse_ctl_kill_sb, 212 }; 213 214 int __init fuse_ctl_init(void) 215 { 216 return register_filesystem(&fuse_ctl_fs_type); 217 } 218 219 void fuse_ctl_cleanup(void) 220 { 221 unregister_filesystem(&fuse_ctl_fs_type); 222 } 223