On Tue, Mar 26, 2019 at 02:02:47PM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> > > This sets S_DAX in inode->i_flags, which can be used with > IS_DAX(). > > The dax option is restricted to non multi-device mounts. > dax interacts with the device directly instead of using bio, so > all bio-hooks which we use for multi-device cannot be performed > here. While regular read/writes could be manipulated with > RAID0/1, mmap() is still an issue. I'm looking for other features that would not work with dax. Disabling multiple devices strikes out device add, device delete and device replace. To be verified: - balance - at least profile changes must be forbidden - defrag - compression - as it needs COW, it won't work on the nodatacow files, thus seems to be ok - resize/grow - this could work without changes, no block relocation is needed, only new structures created - resize/shrink - depends on balance, the block groups from the removed area need to be relocated - swapfiles - I'm sure somebody will try that; I haven't seen any IS_DAX checks in the swapfile activation code
