On Sun, Aug 10, 2025 at 10:03:11AM -0700, Eric Biggers wrote: > I assume you actually still mean fsverity, not fscrypt.
Yes, sorry. > First, it would > be helpful not to use one solution for fscrypt and a totally different > solution for fsverity, as that would increase the maintenance cost well > beyond that of either solution individually. I agree that reducing the number of infrastructures is a goal. But I don't think we should limit us to a single "solution" for different kinds of problems. > > Second, the fsverity info can be loaded very frequently. For example, > curently it's loaded for each 4K data block processed. Well, we can easily keep a once looked up data structure around for any operation that does not leave file system control. So for writing that's a single ioctl context. For read that is a single call into ->readahead, or maybe even ->read_iter. > Also, there > *are* use cases in which most files on the filesystem have fsverity > enabled. Not super common, but they exist. Sure. But the typical use case is a few files, and even that is just a tiny minority of all ext4/f2fs/xfs file systems. > It doesn't really seem like the kind of solution that's a good choice > for a frequently-loaded field. And that's only the load; it's not > getting into the insertion (and resizing) part. Assuming you actually get it down to once per high-level operation above, it will still be absolute noise compared to the I/O generated. > If we're going so far as to use a rhashtable, I have to wonder why we > aren't first prioritizing other fields. For example ext4_inode_info > unconditionally has 40 bytes for fast_commit information, even though > fast_commit is an experimental ext4 feature that isn't enabled on most > filesystems. That's 5 times as much as i_verity_info. And quota has 24 > bytes under CONFIG_QUOTA. And there are even holes in the > ext4_inode_info struct; we could also just improve the field packing! All that does sound like a good idea, independent of what we are discussing here. _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
