On Thu, Sep 03, 2020 at 07:55:49PM +0800, Coly Li wrote: > When calling __generic_fsdax_supported(), a dax-unsupported device may > not have dax_dev as NULL, e.g. the dax related code block is not enabled > by Kconfig. > > Therefore in __generic_fsdax_supported(), to check whether a device > supports DAX or not, the following order should be performed, > - If dax_dev pointer is NULL, it means the device driver explicitly > announce it doesn't support DAX. Then it is OK to directly return > false from __generic_fsdax_supported(). > - If dax_dev pointer is NOT NULL, it might be because the driver doesn't > support DAX and not explicitly initialize related data structure. Then > bdev_dax_supported() should be called for further check. > > IMHO if device driver desn't explicitly set its dax_dev pointer to NULL, > this is not a bug. Calling bdev_dax_supported() makes sure they can be > recognized as dax-unsupported eventually. > > This patch does the following change for the above purpose, > - if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) { > + if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) { > > > Fixes: c2affe920b0e ("dax: do not print error message for non-persistent > memory block device") > Signed-off-by: Coly Li <col...@suse.de>
I hate to do this because I realize this is a bug which people really need fixed. However, shouldn't we also check (!dax_dev || !bdev_dax_supported()) as the _first_ check in __generic_fsdax_supported()? It seems like the other pr_info's could also be called when DAX is not supported and we probably don't want them to be? Perhaps that should be a follow on patch though. So... As a direct fix to c2affe920b0e Reviewed-by: Ira Weiny <ira.we...@intel.com> > Cc: Adrian Huang <ahuan...@lenovo.com> > Cc: Ira Weiny <ira.we...@intel.com> > Cc: Jan Kara <j...@suse.com> > Cc: Mike Snitzer <snit...@redhat.com> > Cc: Pankaj Gupta <pankaj.gupta.li...@gmail.com> > Cc: Vishal Verma <vishal.l.ve...@intel.com> > --- > drivers/dax/super.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > index 32642634c1bb..e5767c83ea23 100644 > --- a/drivers/dax/super.c > +++ b/drivers/dax/super.c > @@ -100,7 +100,7 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev, > return false; > } > > - if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) { > + if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) { > pr_debug("%s: error: dax unsupported by block device\n", > bdevname(bdev, buf)); > return false; > -- > 2.26.2 > _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-le...@lists.01.org