On Mon, Jun 29, 2020 at 12:04:03PM +0000, Satya Tangirala via Linux-f2fs-devel wrote:
> diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
> index 4fa18fff9c4e..1ea9369a7688 100644
> --- a/fs/crypto/bio.c
> +++ b/fs/crypto/bio.c
> @@ -41,6 +41,52 @@ void fscrypt_decrypt_bio(struct bio *bio)
> }
> EXPORT_SYMBOL(fscrypt_decrypt_bio);
>
> +static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
> + pgoff_t lblk, sector_t pblk,
> + unsigned int len)
> +{
> + const unsigned int blockbits = inode->i_blkbits;
> + const unsigned int blocks_per_page = 1 << (PAGE_SHIFT - blockbits);
> + struct bio *bio;
> + int ret, err = 0;
> + int num_pages = 0;
> +
> + /* This always succeeds since __GFP_DIRECT_RECLAIM is set. */
> + bio = bio_alloc(GFP_NOFS, BIO_MAX_PAGES);
> +
> + while (len) {
> + unsigned int blocks_this_page = min(len, blocks_per_page);
> + unsigned int bytes_this_page = blocks_this_page << blockbits;
> +
> + if (num_pages == 0) {
> + fscrypt_set_bio_crypt_ctx(bio, inode, lblk, GFP_NOFS);
> + bio_set_dev(bio, inode->i_sb->s_bdev);
> + bio->bi_iter.bi_sector =
> + pblk << (blockbits - SECTOR_SHIFT);
> + bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
> + }
> + ret = bio_add_page(bio, ZERO_PAGE(0), bytes_this_page, 0);
> + if (WARN_ON(ret != bytes_this_page)) {
> + err = -EIO;
> + goto out;
> + }
> + num_pages++;
> + len -= blocks_this_page;
> + lblk += blocks_this_page;
> + pblk += blocks_this_page;
> + if (num_pages == BIO_MAX_PAGES || !len) {
> + err = submit_bio_wait(bio);
> + if (err)
> + goto out;
> + bio_reset(bio);
> + num_pages = 0;
> + }
> + }
> +out:
> + bio_put(bio);
> + return err;
> +}
I just realized we missed something.
With the new IV_INO_LBLK_32 IV generation strategy, logically contiguous blocks
don't necessarily have contiguous IVs.
So we need to check fscrypt_mergeable_bio() here.
Also it *should* be checked once per block, not once per page. However, that
means that ext4_mpage_readpages() and f2fs_mpage_readpages() are wrong too,
since they only check fscrypt_mergeable_bio() once per page.
Given that difficulty, and the fact that IV_INO_LBLK_32 only has limited use
cases on specific hardware, I suggest that for now we simply restrict inline
encryption with IV_INO_LBLK_32 to the blocksize == PAGE_SIZE case.
(Checking fscrypt_mergeable_bio() once per page is still needed.)
I.e., on top of this patch:
diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 1ea9369a7688..b048a0e38516 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -74,7 +74,8 @@ static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
len -= blocks_this_page;
lblk += blocks_this_page;
pblk += blocks_this_page;
- if (num_pages == BIO_MAX_PAGES || !len) {
+ if (num_pages == BIO_MAX_PAGES || !len ||
+ !fscrypt_mergeable_bio(bio, inode, lblk)) {
err = submit_bio_wait(bio);
if (err)
goto out;
diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
index ec514bc8ee86..097c5a565a21 100644
--- a/fs/crypto/inline_crypt.c
+++ b/fs/crypto/inline_crypt.c
@@ -84,6 +84,19 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
if (!(sb->s_flags & SB_INLINECRYPT))
return 0;
+ /*
+ * When a page contains multiple logically contiguous filesystem blocks,
+ * some filesystem code only calls fscrypt_mergeable_bio() for the first
+ * block in the page. This is fine for most of fscrypt's IV generation
+ * strategies, where contiguous blocks imply contiguous IVs. But it
+ * doesn't work with IV_INO_LBLK_32. For now, simply exclude
+ * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption.
+ */
+ if ((fscrypt_policy_flags(&ci->ci_policy) &
+ FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&
+ sb->s_blocksize != PAGE_SIZE)
+ return 0;
+
