On Wed, Jul 22, 2020 at 11:44:07PM +0100, Matthew Wilcox wrote: > On Wed, Jul 22, 2020 at 03:34:04PM -0700, Eric Biggers wrote: > > > Which means you are now placing a new constraint on this code in > > > that we cannot ever, in future, zero entire blocks here. > > > > > > This code can issue arbitrary sized zeroing bios - multiple entire fs blocks > > > blocks if necessary - so I think constraining it to only support > > > partial block zeroing by adding a warning like this is no correct. > > > > In v3 and earlier this instead had the code to set an encryption context: > > > > fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, > > GFP_KERNEL); > > > > Would you prefer that, even though the call to fscrypt_set_bio_crypt_ctx() would > > always be a no-op currently (since for now, iomap_dio_zero() will never be > > called with an encrypted file) and thus wouldn't be properly tested? > > > > BTW, iomap_dio_zero() is actually limited to one page, so it's not quite > > "arbitrary sizes". > > I have a patch for that > > http://git.infradead.org/users/willy/pagecache.git/commitdiff/1a4d72a890ca9c2ea3d244a6153511ae674ce1d8 No you don't :-) Your patch is for iomap_zero_range() in fs/iomap/buffered-io.c. It doesn't touch fs/iomap/direct-io.c which is what we're talking about here. > It's not going to cause a problem for crossing a 2^32 boundary because > pages are naturally aligned and don't get that big. Well, the boundary can actually occur at any block. But it's not relevant here because (a) fs/iomap/buffered-io.c doesn't yet support encryption anyway, since neither ext4 nor f2fs use it; and (b) iomap_zero_range() just writes to the pagecache, and the bios aren't actually issued until ->writepages(). - Eric
