Re: [PATCH v4 2/7] direct-io: add support for fscrypt using blk-crypto

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 07/20, Satya Tangirala wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Set bio crypt contexts on bios by calling into fscrypt when required,
> and explicitly check for DUN continuity when adding pages to the bio.
> (While DUN continuity is usually implied by logical block contiguity,
> this is not the case when using certain fscrypt IV generation methods
> like IV_INO_LBLK_32).
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> Co-developed-by: Satya Tangirala <satyat@google.com>
> Signed-off-by: Satya Tangirala <satyat@google.com>

Reviwed-by: Jaegeuk Kim <jaegeuk@kernel.org>

> ---
>  fs/direct-io.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 6d5370eac2a8..f27f7e3780ee 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -24,6 +24,7 @@
>  #include <linux/module.h>
>  #include <linux/types.h>
>  #include <linux/fs.h>
> +#include <linux/fscrypt.h>
>  #include <linux/mm.h>
>  #include <linux/slab.h>
>  #include <linux/highmem.h>
> @@ -411,6 +412,7 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
>  	      sector_t first_sector, int nr_vecs)
>  {
>  	struct bio *bio;
> +	struct inode *inode = dio->inode;
>  
>  	/*
>  	 * bio_alloc() is guaranteed to return a bio when allowed to sleep and
> @@ -418,6 +420,9 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
>  	 */
>  	bio = bio_alloc(GFP_KERNEL, nr_vecs);
>  
> +	fscrypt_set_bio_crypt_ctx(bio, inode,
> +				  sdio->cur_page_fs_offset >> inode->i_blkbits,
> +				  GFP_KERNEL);
>  	bio_set_dev(bio, bdev);
>  	bio->bi_iter.bi_sector = first_sector;
>  	bio_set_op_attrs(bio, dio->op, dio->op_flags);
> @@ -782,9 +787,17 @@ static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
>  		 * current logical offset in the file does not equal what would
>  		 * be the next logical offset in the bio, submit the bio we
>  		 * have.
> +		 *
> +		 * When fscrypt inline encryption is used, data unit number
> +		 * (DUN) contiguity is also required.  Normally that's implied
> +		 * by logical contiguity.  However, certain IV generation
> +		 * methods (e.g. IV_INO_LBLK_32) don't guarantee it.  So, we
> +		 * must explicitly check fscrypt_mergeable_bio() too.
>  		 */
>  		if (sdio->final_block_in_bio != sdio->cur_page_block ||
> -		    cur_offset != bio_next_offset)
> +		    cur_offset != bio_next_offset ||
> +		    !fscrypt_mergeable_bio(sdio->bio, dio->inode,
> +					   cur_offset >> dio->inode->i_blkbits))
>  			dio_bio_submit(dio, sdio);
>  	}
>  
> -- 
> 2.28.0.rc0.105.gf9edc3c819-goog