X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fdevpts%2Finode.c;h=d5f8c96964be9a25f8235c869472b95a77ebbecc;hb=8a1eaa6a5697c4554ecacbd021c668f51318c09e;hp=58b719006af1c53797f2becf61adc5f3747640d9;hpb=945cf2c79f6fbb1b74e3b0ca08f48b6af56ad412;p=safe%2Fjmp%2Flinux-2.6 diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 58b7190..d5f8c96 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -18,14 +18,13 @@ #include #include #include +#include #include #include #include #include #include -#define DEVPTS_SUPER_MAGIC 0x1cd1 - #define DEVPTS_DEFAULT_MODE 0600 /* * ptmx is a new node in /dev/pts and will be unused in legacy (single- @@ -90,6 +89,15 @@ static inline struct super_block *pts_sb_from_inode(struct inode *inode) #define PARSE_MOUNT 0 #define PARSE_REMOUNT 1 +/* + * parse_mount_options(): + * Set @opts to mount options specified in @data. If an option is not + * specified in @data, set it to its default value. The exception is + * 'newinstance' option which can only be set/cleared on a mount (i.e. + * cannot be changed during remount). + * + * Note: @data may be NULL (in which case all options are set to default). + */ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) { char *p; @@ -322,124 +330,74 @@ static int compare_init_pts_sb(struct super_block *s, void *p) } /* - * 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 pts_mount_opts *opts, struct vfsmount *mnt) -{ - int err; - struct pts_fs_info *fsi; - - err = get_sb_nodev(fs_type, flags, data, devpts_fill_super, mnt); - if (err) - return err; - - fsi = DEVPTS_SB(mnt->mnt_sb); - memcpy(&fsi->mount_opts, opts, sizeof(opts)); - - return 0; -} - -/* - * get_init_pts_sb() + * devpts_get_sb() + * + * If the '-o newinstance' mount option was specified, mount a new + * (private) instance of devpts. PTYs created in this instance are + * independent of the PTYs in other devpts instances. + * + * If the '-o newinstance' option was not specified, mount/remount the + * initial kernel mount of devpts. This type of mount gives the + * legacy, single-instance semantics. * - * This interface is needed to support multiple namespace semantics in - * devpts while preserving backward compatibility of the current 'single- - * namespace' semantics. i.e all mounts of devpts without the 'newinstance' - * mount option should bind to the initial kernel mount, like - * get_sb_single(). + * The 'newinstance' option is needed to support multiple namespace + * semantics in devpts while preserving backward compatibility of the + * current 'single-namespace' semantics. i.e all mounts of devpts + * without the 'newinstance' mount option should bind to the initial + * kernel mount, like get_sb_single(). * - * Mounts with 'newinstance' option create a new private namespace. + * Mounts with 'newinstance' option create a new, private namespace. * - * But for single-mount semantics, devpts cannot use get_sb_single(), + * NOTE: + * + * For single-mount semantics, devpts cannot use get_sb_single(), * because get_sb_single()/sget() find and use the super-block from * the most recent mount of devpts. But that recent mount may be a * 'newinstance' mount and get_sb_single() would pick the newinstance * super-block instead of the initial super-block. - * - * This interface is identical to get_sb_single() except that it - * consistently selects the 'single-namespace' superblock even in the - * presence of the private namespace (i.e 'newinstance') super-blocks. */ -static int get_init_pts_sb(struct file_system_type *fs_type, int flags, - void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) +static int devpts_get_sb(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data, struct vfsmount *mnt) { - struct super_block *s; - struct pts_fs_info *fsi; int error; + struct pts_mount_opts opts; + struct super_block *s; + + error = parse_mount_options(data, PARSE_MOUNT, &opts); + if (error) + return error; + + if (opts.newinstance) + s = sget(fs_type, NULL, set_anon_super, NULL); + else + s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); - s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); if (IS_ERR(s)) return PTR_ERR(s); if (!s->s_root) { s->s_flags = flags; error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); - if (error) { - up_write(&s->s_umount); - deactivate_super(s); - return error; - } + if (error) + goto out_undo_sget; s->s_flags |= MS_ACTIVE; } simple_set_mnt(mnt, s); - fsi = DEVPTS_SB(mnt->mnt_sb); - memcpy(&fsi->mount_opts, opts, sizeof(opts)); + memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts)); - return 0; -} - -/* - * 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 pts_mount_opts *opts, struct vfsmount *mnt) -{ - int err; - - err = get_init_pts_sb(fs_type, flags, data, opts, mnt); - if (err) - return err; - - return err; -} - -static int devpts_get_sb(struct file_system_type *fs_type, - int flags, const char *dev_name, void *data, struct vfsmount *mnt) -{ - int error; - struct pts_mount_opts opts; - - memset(&opts, 0, sizeof(opts)); - if (data) { - error = parse_mount_options(data, PARSE_MOUNT, &opts); - if (error) - return error; - } - - if (opts.newinstance) - error = new_pts_mount(fs_type, flags, data, &opts, mnt); - else - error = init_pts_mount(fs_type, flags, data, &opts, mnt); - - if (error) - return error; - - error = mknod_ptmx(mnt->mnt_sb); + error = mknod_ptmx(s); if (error) goto out_dput; return 0; out_dput: - dput(mnt->mnt_sb->s_root); - up_write(&mnt->mnt_sb->s_umount); - deactivate_super(mnt->mnt_sb); + dput(s->s_root); /* undo dget() in simple_set_mnt() */ + +out_undo_sget: + deactivate_locked_super(s); return error; } @@ -464,7 +422,6 @@ static void devpts_kill_sb(struct super_block *sb) } static struct file_system_type devpts_fs_type = { - .owner = THIS_MODULE, .name = "devpts", .get_sb = devpts_get_sb, .kill_sb = devpts_kill_sb, @@ -598,18 +555,11 @@ static int __init init_devpts_fs(void) int err = register_filesystem(&devpts_fs_type); if (!err) { devpts_mnt = kern_mount(&devpts_fs_type); - if (IS_ERR(devpts_mnt)) + if (IS_ERR(devpts_mnt)) { err = PTR_ERR(devpts_mnt); + unregister_filesystem(&devpts_fs_type); + } } return err; } - -static void __exit exit_devpts_fs(void) -{ - unregister_filesystem(&devpts_fs_type); - mntput(devpts_mnt); -} - module_init(init_devpts_fs) -module_exit(exit_devpts_fs) -MODULE_LICENSE("GPL");