Re: [RFC PATCH 07/21] ubifs: Migrate to acomp compression API

Simon Horman
2023-07-21T09:19:46Z

On Tue, Jul 18, 2023 at 02:58:33PM +0200, Ard Biesheuvel wrote:
> UBIFS is one of the remaining users of the obsolete 'comp' compression
> API exposed by the crypto subsystem. Given that it operates strictly on
> contiguous buffers that are either entirely in lowmem or covered by a
> single page, the conversion to the acomp API is quite straight-forward.
>
> Only synchronous acomp implementations are considered at the moment, and
> whether or not a future conversion to permit asynchronous ones too will
> be worth the effort remains to be seen.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

...

> @@ -197,11 +205,24 @@ int ubifs_decompress(const struct ubifs_info *c, const void *in_buf,
> static int __init compr_init(struct ubifs_compressor *compr)
> {
> if (compr->capi_name) {
> - compr->cc = crypto_alloc_comp(compr->capi_name, 0, 0);
> + long ret;
> +
> + compr->cc = crypto_alloc_acomp(compr->capi_name, 0,
> + CRYPTO_ALG_ASYNC);
> if (IS_ERR(compr->cc)) {
> + ret = PTR_ERR(compr->cc);
> + } else {
> + compr->req = acomp_request_alloc(compr->cc);
> + if (!compr->req) {
> + crypto_free_acomp(compr->cc);
> + ret = -ENOMEM;
> + }
> + }

Hi Ard,

clang-16 W=1 and Smatch flag that ret may not always be initialised here.

> +
> + if (ret) {
> pr_err("UBIFS error (pid %d): cannot initialize compressor %s, error %ld",
> - current->pid, compr->name, PTR_ERR(compr->cc));
> - return PTR_ERR(compr->cc);
> + current->pid, compr->name, ret);
> + return ret;
> }
> }
>

...

> diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
> index 4c36044140e7eba9..2225de5b8ef50f71 100644
> --- a/fs/ubifs/ubifs.h
> +++ b/fs/ubifs/ubifs.h
> @@ -32,6 +32,7 @@
> #include <crypto/hash_info.h>
> #include <crypto/hash.h>
> #include <crypto/algapi.h>
> +#include <crypto/acompress.h>
>
> #include <linux/fscrypt.h>
>
> @@ -849,7 +850,8 @@ struct ubifs_node_range {
> */
> struct ubifs_compressor {
> int compr_type;
> - struct crypto_comp *cc;
> + struct crypto_acomp *cc;
> + struct acomp_req *req;

Please consider adding @req to the kernel doc for this structure.

> struct mutex *comp_mutex;
> struct mutex *decomp_mutex;
> const char *name;

...