isofs: Refuse RW mount of the filesystem instead of making it RO (17b7f7cf) · Commits · 戴 / test

Refuse RW mount of isofs filesystem. So far we just silently changed it to RO mount but when the media is writeable, block layer won't notice this change and thus will think device is used RW and will block eject button of the drive. That is unexpected by users because for non-writeable media eject button works just fine. Userspace mount(8) command handles this just fine and retries mounting with MS_RDONLY set so userspace shouldn't see any regression. Plus any tool mounting isofs is likely confronted with the case of read-only media where block layer already refuses to mount the filesystem without MS_RDONLY set so our behavior shouldn't be anything new for it. Reported-by:

Hui Wang <hui.wang@canonical.com> Signed-off-by:

Jan Kara <jack@suse.cz>

fs/isofs/inode.c

+5 −11

Original line number	Diff line number	Diff line
		@@ -117,8 +117,8 @@ static void destroy_inodecache(void)

		static int isofs_remount(struct super_block sb, int flags, char *data)
		{
		/* we probably want a lot more here */
		*flags \|= MS_RDONLY;
		if (!(*flags & MS_RDONLY))
		return -EROFS;
		return 0;
		}

		@@ -763,15 +763,6 @@ root_found:
		*/
		s->s_maxbytes = 0x80000000000LL;

		/*
		* The CDROM is read-only, has no nodes (devices) on it, and since
		* all of the files appear to be owned by root, we really do not want
		* to allow suid. (suid or devices will not show up unless we have
		* Rock Ridge extensions)
		*/

		s->s_flags \|= MS_RDONLY /* \| MS_NODEV \| MS_NOSUID */;

		/* Set this for reference. Its not currently used except on write
		which we don't have .. */

		@@ -1530,6 +1521,9 @@ struct inode isofs_iget(struct super_block sb,
		static struct dentry isofs_mount(struct file_system_type fs_type,
		int flags, const char dev_name, void data)
		{
		/* We don't support read-write mounts */
		if (!(flags & MS_RDONLY))
		return ERR_PTR(-EACCES);
		return mount_bdev(fs_type, flags, dev_name, data, isofs_fill_super);
		}

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