Re: [PATCH v2 19/20] btrfs: encrypt normal file extent data if appropriate

Josef Bacik
2022-09-08T20:20:03Z

On Mon, Sep 05, 2022 at 08:35:34PM -0400, Sweet Tea Dorminy wrote:
> From: Omar Sandoval <osandov@osandov.com>
>
> Add in the necessary calls to encrypt and decrypt data to achieve
> encryption of normal data.
>

A little more description of what these bounce pages are and what we're doing
with them.

> Signed-off-by: Omar Sandoval <osandov@osandov.com>
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
> ---
> fs/btrfs/extent_io.c | 56 ++++++++++++++++++++++++++++++++++++-----
> fs/btrfs/file-item.c | 9 +++++--
> fs/btrfs/fscrypt.c | 23 ++++++++++++++++-
> fs/btrfs/tree-checker.c | 11 +++++---
> 4 files changed, 87 insertions(+), 12 deletions(-)
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index a467a7553bd9..8adcee599844 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -183,6 +183,7 @@ static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl)
> {
> struct bio *bio;
> struct bio_vec *bv;
> + struct page *first_page;
> struct inode *inode;
> int mirror_num;
>
> @@ -191,13 +192,17 @@ static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl)
>
> bio = bio_ctrl->bio;
> bv = bio_first_bvec_all(bio);
> - inode = bv->bv_page->mapping->host;
> + first_page = bio_first_page_all(bio);
> + if (fscrypt_is_bounce_page(first_page))
> + inode = fscrypt_pagecache_page(first_page)->mapping->host;
> + else
> + inode = first_page->mapping->host;
> mirror_num = bio_ctrl->mirror_num;
>
> /* Caller should ensure the bio has at least some range added */
> ASSERT(bio->bi_iter.bi_size);
>
> - btrfs_bio(bio)->file_offset = page_offset(bv->bv_page) + bv->bv_offset;
> + btrfs_bio(bio)->file_offset = page_offset(first_page) + bv->bv_offset;
>
> if (!is_data_inode(inode))
> btrfs_submit_metadata_bio(inode, bio, mirror_num);
> @@ -2810,9 +2815,19 @@ static void end_bio_extent_writepage(struct btrfs_bio *bbio)
> ASSERT(!bio_flagged(bio, BIO_CLONED));
> bio_for_each_segment_all(bvec, bio, iter_all) {
> struct page *page = bvec->bv_page;
> - struct inode *inode = page->mapping->host;
> - struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
> - const u32 sectorsize = fs_info->sectorsize;
> + struct inode *inode;
> + struct btrfs_fs_info *fs_info;
> + u32 sectorsize;
> + struct page *bounce_page = NULL;
> +
> + if (fscrypt_is_bounce_page(page)) {
> + bounce_page = page;
> + page = fscrypt_pagecache_page(bounce_page);
> + }
> +
> + inode = page->mapping->host;
> + fs_info = btrfs_sb(inode->i_sb);
> + sectorsize = fs_info->sectorsize;
>
> /* Our read/write should always be sector aligned. */
> if (!IS_ALIGNED(bvec->bv_offset, sectorsize))
> @@ -2833,7 +2848,7 @@ static void end_bio_extent_writepage(struct btrfs_bio *bbio)
> }
>
> end_extent_writepage(page, error, start, end);
> -
> + fscrypt_free_bounce_page(bounce_page);
> btrfs_page_clear_writeback(fs_info, page, start, bvec->bv_len);
> }
>
> @@ -3029,6 +3044,17 @@ static void end_bio_extent_readpage(struct btrfs_bio *bbio)
> }
> }
>
> + if (likely(uptodate)) {
> + if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
> + int ret = fscrypt_decrypt_pagecache_blocks(page,
> + bvec->bv_len,
> + bvec->bv_offset);
> + if (ret) {
> + error_bitmap = (unsigned int) -1;
> + uptodate = false;
> + }

This thing. Thanks,

Josef