On Mon 02-05-16 09:50:37, Daeho Jeong wrote: > We check whether a new handle can be started through > ext4_journal_check_start() and the function refuses to start the handle > when the filesystem is mounted with read-only. But now, when we remount > the filesystem with read-only option, already started handles are > allowed to be written on disk, but the subsequent metadata modification > using the handles are refused by ext4_journal_check_start(). > > As an example, in ext4_evict_inode(), i_size can be set to 0 using > a successfully started handle, but, when we remount the filesystem > with read-only option at that time, the subsequent ext4_truncate() > will be failed and the filesystem integrity will be damaged. > > Therefore, we need to permit the metadata modification using already > started handles to be proceeded, even if s_flags of the filesystem is > set to MS_RDONLY. > > Kitae found the problem and suggested the solution. So can you share a reproducer for this issue? Because my initial thinking is that checks during remount should fail the remount with EBUSY if there is any modification outstanding... If they don't we have a racy remount and fs-freezing code, which is a bug. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
