On Tue, Aug 25, 2020 at 04:50:56PM +0200, Jan Kara wrote: > Do you mean that address_space filesystem uses to access its metadata on > /dev/sda will be different from the address_space you will see when reading > say /dev/sda? Thus these will be completely separate (and incoherent) > caches? Yes. > Although this would be simple it will break userspace I'm afraid. > There are situations where tools read e.g. superblock of a mounted > filesystem from the block device and rely on the data to be reasonably > recent. Even worse e.g. tune2fs or e2fsck can *modify* superblock of a > mounted filesystem through the block device (e.g. to set 'fsck after X > mounts' fields and similar). We've not had any problems when XFS stopped using the block device address space 9.5 years ago.
