gid_t gid;
umode_t mode;
umode_t ptmxmode;
+ int newinstance;
};
enum {
- Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode,
+ Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance,
Opt_err
};
{Opt_mode, "mode=%o"},
#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
{Opt_ptmxmode, "ptmxmode=%o"},
+ {Opt_newinstance, "newinstance"},
#endif
{Opt_err, NULL}
};
static inline struct super_block *pts_sb_from_inode(struct inode *inode)
{
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
return inode->i_sb;
-
+#endif
return devpts_mnt->mnt_sb;
}
-static int parse_mount_options(char *data, struct pts_mount_opts *opts)
+#define PARSE_MOUNT 0
+#define PARSE_REMOUNT 1
+
+static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
{
char *p;
opts->mode = DEVPTS_DEFAULT_MODE;
opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
+ /* newinstance makes sense only on initial mount */
+ if (op == PARSE_MOUNT)
+ opts->newinstance = 0;
+
while ((p = strsep(&data, ",")) != NULL) {
substring_t args[MAX_OPT_ARGS];
int token;
return -EINVAL;
opts->ptmxmode = option & S_IALLUGO;
break;
+ case Opt_newinstance:
+ /* newinstance makes sense only on initial mount */
+ if (op == PARSE_MOUNT)
+ opts->newinstance = 1;
+ break;
#endif
default:
printk(KERN_ERR "devpts: called with bogus options\n");
struct pts_fs_info *fsi = DEVPTS_SB(sb);
struct pts_mount_opts *opts = &fsi->mount_opts;
- err = parse_mount_options(data, opts);
+ err = parse_mount_options(data, PARSE_REMOUNT, opts);
/*
* parse_mount_options() restores options to default values
{
if (devpts_mnt)
return devpts_mnt->mnt_sb == s;
+ return 0;
+}
+
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+/*
+ * Safely parse the mount options in @data and update @opts.
+ *
+ * devpts ends up parsing options two times during mount, due to the
+ * two modes of operation it supports. The first parse occurs in
+ * devpts_get_sb() when determining the mode (single-instance or
+ * multi-instance mode). The second parse happens in devpts_remount()
+ * or new_pts_mount() depending on the mode.
+ *
+ * Parsing of options modifies the @data making subsequent parsing
+ * incorrect. So make a local copy of @data and parse it.
+ *
+ * Return: 0 On success, -errno on error
+ */
+static int safe_parse_mount_options(void *data, struct pts_mount_opts *opts)
+{
+ int rc;
+ void *datacp;
+
+ if (!data)
+ return 0;
+
+ /* Use kstrdup() ? */
+ datacp = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!datacp)
+ return -ENOMEM;
+
+ memcpy(datacp, data, PAGE_SIZE);
+ rc = parse_mount_options((char *)datacp, PARSE_MOUNT, opts);
+ kfree(datacp);
+
+ return rc;
+}
+
+/*
+ * Mount a new (private) instance of devpts. PTYs created in this
+ * instance are independent of the PTYs in other devpts instances.
+ */
+static int new_pts_mount(struct file_system_type *fs_type, int flags,
+ void *data, struct vfsmount *mnt)
+{
+ int err;
+ struct pts_fs_info *fsi;
+ struct pts_mount_opts *opts;
+
+ printk(KERN_NOTICE "devpts: newinstance mount\n");
+
+ err = get_sb_nodev(fs_type, flags, data, devpts_fill_super, mnt);
+ if (err)
+ return err;
+
+ fsi = DEVPTS_SB(mnt->mnt_sb);
+ opts = &fsi->mount_opts;
+
+ err = parse_mount_options(data, PARSE_MOUNT, opts);
+ if (err)
+ goto fail;
+
+ err = mknod_ptmx(mnt->mnt_sb);
+ if (err)
+ goto fail;
return 0;
+
+fail:
+ dput(mnt->mnt_sb->s_root);
+ deactivate_super(mnt->mnt_sb);
+ return err;
+}
+
+/*
+ * Check if 'newinstance' mount option was specified in @data.
+ *
+ * Return: -errno on error (eg: invalid mount options specified)
+ * : 1 if 'newinstance' mount option was specified
+ * : 0 if 'newinstance' mount option was NOT specified
+ */
+static int is_new_instance_mount(void *data)
+{
+ int rc;
+ struct pts_mount_opts opts;
+
+ if (!data)
+ return 0;
+
+ rc = safe_parse_mount_options(data, &opts);
+ if (!rc)
+ rc = opts.newinstance;
+
+ return rc;
}
/*
return simple_set_mnt(mnt, s);
}
+/*
+ * Mount or remount the initial kernel mount of devpts. This type of
+ * mount maintains the legacy, single-instance semantics, while the
+ * kernel still allows multiple-instances.
+ */
+static int init_pts_mount(struct file_system_type *fs_type, int flags,
+ void *data, struct vfsmount *mnt)
+{
+ int err;
+
+ err = get_init_pts_sb(fs_type, flags, data, mnt);
+ if (err)
+ return err;
+
+ err = mknod_ptmx(mnt->mnt_sb);
+ if (err) {
+ dput(mnt->mnt_sb->s_root);
+ deactivate_super(mnt->mnt_sb);
+ }
+
+ return err;
+}
+
static int devpts_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
- return get_init_pts_sb(fs_type, flags, data, mnt);
+ int new;
+
+ new = is_new_instance_mount(data);
+ if (new < 0)
+ return new;
+
+ if (new)
+ return new_pts_mount(fs_type, flags, data, mnt);
+
+ return init_pts_mount(fs_type, flags, data, mnt);
}
+#else
+/*
+ * This supports only the legacy single-instance semantics (no
+ * multiple-instance semantics)
+ */
+static int devpts_get_sb(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data, struct vfsmount *mnt)
+{
+ return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
+}
+#endif
static void devpts_kill_sb(struct super_block *sb)
{
mutex_lock(&root->d_inode->i_mutex);
dentry = d_find_alias(inode);
- if (dentry && !IS_ERR(dentry)) {
+ if (IS_ERR(dentry))
+ goto out;
+
+ if (dentry) {
inode->i_nlink--;
d_delete(dentry);
- dput(dentry);
+ dput(dentry); // d_alloc_name() in devpts_pty_new()
}
+ dput(dentry); // d_find_alias above
+
+out:
mutex_unlock(&root->d_inode->i_mutex);
}
git.openpandora.org / pandora-kernel.git / blobdiff