Hello Milan, > -----Original Message----- > From: Milan Broz [mailto:gmazyl...@gmail.com] > Sent: Thursday, September 24, 2020 2:16 AM > To: Eric Biggers <ebigg...@kernel.org>; Mike Snitzer <snit...@redhat.com> > Cc: Sudhakar Panneerselvam <sudhakar.panneersel...@oracle.com>; > damien.lem...@wdc.com; ssudhak...@gmail.com; Martin Petersen > <martin.peter...@oracle.com>; dm-cr...@saout.de; dm-devel@redhat.com; > Shirley Ma <shirley...@oracle.com>; mpato...@redhat.com; > a...@redhat.com > Subject: Re: [dm-devel] [RFC PATCH 0/2] dm crypt: Allow unaligned buffer > lengths for skcipher devices > > On 24/09/2020 07:14, Eric Biggers wrote: > > On Wed, Sep 23, 2020 at 09:27:32PM -0400, Mike Snitzer wrote: > >> You've clearly done a nice job with these changes. Looks clean. > >> > >> BUT, I'm struggling to just accept that dm-crypt needs to go to these > >> extra lengths purely because of one bad apple usecase. > >> > >> These alignment constraints aren't new. Are there other portions of > >> Linux's crypto subsystem that needed comparable fixes in order to work > >> with Microsfot OS initiated IO through a guest? > >> > >> You forecast that these same kinds of changes are needed for AEAD and > >> dm-integrity... that's alarming. > >> > >> Are we _certain_ there is no other way forward? > >> (Sorry I don't have suggestions.. I'm in "fact finding mode" ;) > >> > > > > I don't understand why this is needed, since dm-crypt already sets its > > logical_block_size to its crypto sector_size. Isn't it expected that I/O > > that > > isn't aligned to logical_block_size fails? It's the I/O submitter's > > responsibility to ensure logical_block_size alignment of all I/O segments. > > Exactly how is the misaligned I/O actually being submitted here? > > Thanks for mentioning it - exactly that I asked when reading this patch... > It seems that we are here fixing a problem that is just caused when someone > ignores clearly set restrictions. > > Who is submitting these bioses? Why can it not be fixed there? > > What happens with writes to fs journals, etc., is it still safe if we are > processing such unaligned bios?
I don't follow your question regarding fs journals. I am not sure why it is not safe to process unaligned bio segment lengths of fs journals writes. Could you explain with some example on why that would be a problem? Please see my reply to Eric's/Mike's email, in that, I explained why this issue needs to be fixed in dm-crypt. I hope I have answered to your questions there. If not, let me know, I will try to answer. Thanks Sudhakar > > Milan -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
