On Wed, Aug 07, 2019 at 04:10:05PM +0200, Johannes Thumshirn wrote: > On Tue, Jul 30, 2019 at 07:19:04PM +0200, David Sterba wrote: > > On Thu, Jul 25, 2019 at 11:33:51AM +0200, Johannes Thumshirn wrote: > > > From: David Sterba <dste...@suse.com> > > > > > > Export supported checksum algorithms via sysfs. > > > > I wonder if we should also export the implementation that would be used. > > This could be crross referenced with /proc/crypto, but having it in one > > place would be IMHO convenient. Also for the case when the kernel > > module is missing. > > > > Currently the hash names are printed as comma separated values so we'd > > need bit something structured: > > > > crc32c: crc32c-intel > > xxhash64: xxhash-generic > > I thought a bit more about it and it's not quite that easy as I would need to > have access to the respective "struct crypto_shash". For the currently used > checksum this isn't much of a problem, as I get it via "struct btrfs_fs_info". > > But this sysfs attribute lists all the checksumming algorithms the current > btrfs version is able to use irrespectively of the currently mounted > file-systems. > > So yes I can do it but I think this is for another sysfs attribute which shows > the used checksumming algorithm for this FS, not the supported checksumming > algorithms.
I see. We can't know which implementation would be used until we actually try to use it, so two sysfs files would make more sense. Plain list for all supported algos and one with the implementation for a given mounted filesystem.
