On Tue, 2017-05-02 at 23:19 +0300, Amir Goldstein wrote: > We need a helper for VFS to check if struct super_block field s_uuid > was filled by the filesystem, before consumers can use it. > > The libnvdimm code already has a private helper to check if uuid is > null > and the helper name is not using a private namespace prefix, which > prevents us from using the same helper name as a common function. > Hmm... Have you checked my branch here: https://bitbucket.org/andy-shev/linux/branch/topic%2Fuuid ? Probably not. I have number of patches to make UUID API used kernel wide. ...including helpers for null UUID check: https://bitbucket.org/andy-shev/linux/commits/79029ebe2c32830f82effc0f0b 62cce2b6eb7fdb?at=topic/uuid > Hoist the libnvdimm helper as an inline helper to linux/uuid.h. > > Suggested-by: Christoph Hellwig <hch@xxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Cc: David Howells <dhowells@xxxxxxxxxx> > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> > --- > drivers/nvdimm/btt_devs.c | 8 +------- > include/linux/uuid.h | 7 +++++++ > 2 files changed, 8 insertions(+), 7 deletions(-) > > Christoph, > > Following your suggestion to provide a helper for checking if > filesystem > had filled sb->s_uuid, here is a patch to add that helper. > > I considered hoisting xfs's uuid_is_nil() helper and uuid_t to uuid.h, > but > that would have been more painful, so just moved this simple helper > instead. > We can continue debating which implementation is better, but that > would be > futile... > > If in the future xfs uuid table code is going to be moved to VFS, we > should > probably move variants of the xfs/uuid.c functions to lib/uuid.c if > those > variants don't already exist. > > CC'ing the maintainers of clearcache and EVM/IMA to see if this helper > should be added (as sanity?) to their code before accessing sb- > >s_uuid. > > I truely hope that EVM/IMA signatures do not expect xfs/ubifs to keep > exporting null s_uuid, because if they do, then starting to export > s_uuid > for xfs/ubifs may require a new config/mkfs/mount option and that > would > be a shame. > > Cheers, > Amir. > > diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c > index 97dd292..d0fcda2 100644 > --- a/drivers/nvdimm/btt_devs.c > +++ b/drivers/nvdimm/btt_devs.c > @@ -17,6 +17,7 @@ > #include <linux/slab.h> > #include <linux/fs.h> > #include <linux/mm.h> > +#include <linux/uuid.h> > #include "nd-core.h" > #include "btt.h" > #include "nd.h" > @@ -222,13 +223,6 @@ struct device *nd_btt_create(struct nd_region > *nd_region) > return dev; > } > > -static bool uuid_is_null(u8 *uuid) > -{ > - static const u8 null_uuid[16]; > - > - return (memcmp(uuid, null_uuid, 16) == 0); > -} > - > /** > * nd_btt_arena_is_valid - check if the metadata layout is valid > * @nd_btt: device with BTT geometry and backing device info > diff --git a/include/linux/uuid.h b/include/linux/uuid.h > index 4dff73a..d3f8656 100644 > --- a/include/linux/uuid.h > +++ b/include/linux/uuid.h > @@ -58,6 +58,13 @@ static inline int uuid_be_cmp(const uuid_be u1, > const uuid_be u2) > return memcmp(&u1, &u2, sizeof(uuid_be)); > } > > +static inline bool uuid_is_null(u8 *uuid) > +{ > + static const u8 null_uuid[16]; > + > + return (memcmp(uuid, null_uuid, 16) == 0); > +} > + > void generate_random_uuid(unsigned char uuid[16]); > > extern void uuid_le_gen(uuid_le *u); -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
