On Mon, Apr 25, 2016 at 05:14:36PM +0000, Verma, Vishal L wrote: > - Application hits EIO doing dax_IO or load/store io > > - It checks badblocks and discovers it's files have lost data > > - It write()s those sectors (possibly converted to file offsets using > fiemap) > ?? ?? * This triggers the fallback path, but if the application is doing > this level of recovery, it will know the sector is bad, and write the > entire sector
This sounds like a mess. > I think if we want to keep allowing arbitrary alignments for the > dax_do_io path, we'd need: > 1. To represent badblocks at a finer granularity (likely cache lines) > 2. To allow the driver to do IO to a *block device* at sub-sector > granularity It's not a block device if it supports DAX. It's byte addressable memory masquerading as a block device.
