On Fri, Sep 18, 2020 at 8:31 AM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > > On Thu, Sep 17, 2020 at 10:30:03PM -0700, Dan Williams wrote: > > From: Jan Kara <jack@xxxxxxx> > > > > DM was calling generic_fsdax_supported() to determine whether a device > > referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that > > they don't have to duplicate common generic checks. High level code > > should call dax_supported() helper which that calls into appropriate > > helper for the particular device. This problem manifested itself as > > kernel messages: > > > > dm-3: error: dax access failed (-95) > > > > when lvm2-testsuite run in cases where a DM device was stacked on top of > > another DM device. > > Is there somewhere where it is documented which of: > > bdev_dax_supported, generic_fsdax_supported, and dax_supported > > one is supposed to use for a given circumstance? generic_fsdax_supported should be private to device drivers populating their dax_operations. I think it deserves a rename at this point. dax_supported() knows how to route through multiple layers of stacked block-devices to ask the "is dax supported" question at each level. > I guess the last two can test a given range w/ blocksize; the first one > only does blocksize; and the middle one also checks with whatever fs > might be mounted? <shrug> > > (I ask because it took me a while to figure out how to revert correctly > the brokenness in rc3-5 that broke my nightly dax fstesting.) Again, apologies for that. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
