On Sun, May 04, 2025 at 10:37:07PM -0700, Christoph Hellwig wrote: > On Fri, May 02, 2025 at 12:39:42PM -0700, Darrick J. Wong wrote: > > Me neither. We can't write 512b blocks to the rt device obviously, but > > I think the whole point of the separate "sector" size is that's the > > maximum size that the fs knows it can write to the device without > > tearing. > > The sector size is really the minimum addressable unit. > > > Maybe there's a way out of this: the only metadata on the realtime > > volume is the rt superblock, whose size is a full fsblock. Perhaps we > > could set/validate the block size of the rt dev with the fsblock size > > instead? > > We still allow subsector dio to the rt device, so this would be a bit > of a sketchy change. I don't understand the 'subsector' in this sentence -- we allow sub-fsblock dio, but not sub-LBA dio, right? So the only thing we need to validate for the rt device is that fsblock >= lbasize to avoid confusing the pagecache when it does IO, as well as user programs that aren't expecting such things. --D
