Re: [RFC PATCH] jffs2: add support for zstd compression

Rui Salvaterra
2021-03-16T14:12:26Z

Hi,

Please ignore this, I noticed a bug. I'll send a fixed v2 shortly.

Thanks,
Rui

On Fri, 12 Mar 2021 at 09:56, Rui Salvaterra <rsalvaterra@gmail.com> wrote:
>
> Implement support for zstd compression in jffs2 at the default compression
> level (3).
>
> Lightly tested in OpenWrt, on a single CPU embedded MIPS32 system (AirGrid M2).
>
> Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
> ---
> Sent as RFC, since I have no idea if locking is required (the crypto API
> implementation doesn't do it, at least).
>
> fs/jffs2/Kconfig | 9 +++
> fs/jffs2/Makefile | 1 +
> fs/jffs2/compr.c | 10 +++
> fs/jffs2/compr.h | 6 ++
> fs/jffs2/compr_zstd.c | 131 +++++++++++++++++++++++++++++++++++++
> fs/jffs2/super.c | 7 ++
> include/uapi/linux/jffs2.h | 1 +
> 7 files changed, 165 insertions(+)
> create mode 100644 fs/jffs2/compr_zstd.c
>
> diff --git a/fs/jffs2/Kconfig b/fs/jffs2/Kconfig
> index 7c96bc107218..31308eb7267b 100644
> --- a/fs/jffs2/Kconfig
> +++ b/fs/jffs2/Kconfig
> @@ -136,6 +136,15 @@ config JFFS2_LZO
> This feature was added in July, 2007. Say 'N' if you need
> compatibility with older bootloaders or kernels.
>
> +config JFFS2_ZSTD
> + bool "JFFS2 zstd compression support" if JFFS2_COMPRESSION_OPTIONS
> + select ZSTD_COMPRESS
> + select ZSTD_DECOMPRESS
> + depends on JFFS2_FS
> + default n
> + help
> + Zstd compression.
> +
> config JFFS2_RTIME
> bool "JFFS2 RTIME compression support" if JFFS2_COMPRESSION_OPTIONS
> depends on JFFS2_FS
> diff --git a/fs/jffs2/Makefile b/fs/jffs2/Makefile
> index 5294969d5bf9..75f84b1467c5 100644
> --- a/fs/jffs2/Makefile
> +++ b/fs/jffs2/Makefile
> @@ -19,4 +19,5 @@ jffs2-$(CONFIG_JFFS2_RUBIN) += compr_rubin.o
> jffs2-$(CONFIG_JFFS2_RTIME) += compr_rtime.o
> jffs2-$(CONFIG_JFFS2_ZLIB) += compr_zlib.o
> jffs2-$(CONFIG_JFFS2_LZO) += compr_lzo.o
> +jffs2-$(CONFIG_JFFS2_ZSTD) += compr_zstd.o
> jffs2-$(CONFIG_JFFS2_SUMMARY) += summary.o
> diff --git a/fs/jffs2/compr.c b/fs/jffs2/compr.c
> index 4849a4c9a0e2..d65e0c39c9c5 100644
> --- a/fs/jffs2/compr.c
> +++ b/fs/jffs2/compr.c
> @@ -237,6 +237,10 @@ uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
> ret = jffs2_selected_compress(JFFS2_COMPR_ZLIB, data_in,
> cpage_out, datalen, cdatalen);
> break;
> + case JFFS2_COMPR_MODE_FORCEZSTD:
> + ret = jffs2_selected_compress(JFFS2_COMPR_ZSTD, data_in,
> + cpage_out, datalen, cdatalen);
> + break;
> default:
> pr_err("unknown compression mode\n");
> }
> @@ -378,6 +382,9 @@ int __init jffs2_compressors_init(void)
> #ifdef CONFIG_JFFS2_LZO
> jffs2_lzo_init();
> #endif
> +#ifdef CONFIG_JFFS2_ZSTD
> + jffs2_zstd_init();
> +#endif
> /* Setting default compression mode */
> #ifdef CONFIG_JFFS2_CMODE_NONE
> jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
> @@ -413,6 +420,9 @@ int jffs2_compressors_exit(void)
> #endif
> #ifdef CONFIG_JFFS2_ZLIB
> jffs2_zlib_exit();
> +#endif
> +#ifdef CONFIG_JFFS2_ZSTD
> + jffs2_zstd_exit();
> #endif
> return 0;
> }
> diff --git a/fs/jffs2/compr.h b/fs/jffs2/compr.h
> index 5e91d578f4ed..8f7032c5ecb2 100644
> --- a/fs/jffs2/compr.h
> +++ b/fs/jffs2/compr.h
> @@ -31,6 +31,7 @@
> #define JFFS2_RTIME_PRIORITY 50
> #define JFFS2_ZLIB_PRIORITY 60
> #define JFFS2_LZO_PRIORITY 80
> +#define JFFS2_ZSTD_PRIORITY 90
>
>
> #define JFFS2_RUBINMIPS_DISABLED /* RUBINs will be used only */
> @@ -42,6 +43,7 @@
> #define JFFS2_COMPR_MODE_FAVOURLZO 3
> #define JFFS2_COMPR_MODE_FORCELZO 4
> #define JFFS2_COMPR_MODE_FORCEZLIB 5
> +#define JFFS2_COMPR_MODE_FORCEZSTD 6
>
> #define FAVOUR_LZO_PERCENT 80
>
> @@ -101,5 +103,9 @@ void jffs2_zlib_exit(void);
> int jffs2_lzo_init(void);
> void jffs2_lzo_exit(void);
> #endif
> +#ifdef CONFIG_JFFS2_ZSTD
> +int jffs2_zstd_init(void);
> +void jffs2_zstd_exit(void);
> +#endif
>
> #endif /* __JFFS2_COMPR_H__ */
> diff --git a/fs/jffs2/compr_zstd.c b/fs/jffs2/compr_zstd.c
> new file mode 100644
> index 000000000000..86b3d28670d7
> --- /dev/null
> +++ b/fs/jffs2/compr_zstd.c
> @@ -0,0 +1,131 @@
> +
> +#include <linux/zstd.h>
> +#include "compr.h"
> +
> +#define ZSTD_DEF_LEVEL 3
> +
> +static ZSTD_CCtx *cctx;
> +static ZSTD_DCtx *dctx;
> +static void *cwksp;
> +static void *dwksp;
> +
> +static ZSTD_parameters zstd_params(void)
> +{
> + return ZSTD_getParams(ZSTD_DEF_LEVEL, 0, 0);
> +}
> +
> +static int zstd_comp_init(void)
> +{
> + int ret = 0;
> + const ZSTD_parameters params = zstd_params();
> + const size_t wksp_size = ZSTD_CCtxWorkspaceBound(params.cParams);
> +
> + cwksp = vzalloc(wksp_size);
> + if (!cwksp) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + cctx = ZSTD_initCCtx(cwksp, wksp_size);
> + if (cctx) {
> + ret = -EINVAL;
> + goto out_free;
> + }
> +out:
> + return ret;
> +out_free:
> + vfree(cwksp);
> + goto out;
> +}
> +
> +static int zstd_decomp_init(void)
> +{
> + int ret = 0;
> + const size_t wksp_size = ZSTD_DCtxWorkspaceBound();
> +
> + dwksp = vzalloc(wksp_size);
> + if (!dwksp) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + dctx = ZSTD_initDCtx(dwksp, wksp_size);
> + if (!dctx) {
> + ret = -EINVAL;
> + goto out_free;
> + }
> +out:
> + return ret;
> +out_free:
> + vfree(dwksp);
> + goto out;
> +}
> +
> +static void zstd_comp_exit(void)
> +{
> + vfree(cwksp);
> + cwksp = NULL;
> + cctx = NULL;
> +}
> +
> +static void zstd_decomp_exit(void)
> +{
> + vfree(dwksp);
> + dwksp = NULL;
> + dctx = NULL;
> +}
> +
> +static int jffs2_zstd_compress(unsigned char *data_in, unsigned char *cpage_out,
> + uint32_t *sourcelen, uint32_t *dstlen)
> +{
> + size_t out_len;
> + const ZSTD_parameters params = zstd_params();
> +
> + out_len = ZSTD_compressCCtx(cctx, cpage_out, *dstlen, data_in, *sourcelen, params);
> + if (ZSTD_isError(out_len) || out_len > *dstlen)
> + return -1;
> + *dstlen = out_len;
> + return 0;
> +}
> +
> +static int jffs2_zstd_decompress(unsigned char *data_in, unsigned char *cpage_out,
> + uint32_t srclen, uint32_t destlen)
> +{
> + size_t out_len;
> +
> + out_len = ZSTD_decompressDCtx(dctx, cpage_out, destlen, data_in, srclen);
> + if (ZSTD_isError(out_len) || out_len != destlen)
> + return -1;
> +
> + return 0;
> +}
> +
> +static struct jffs2_compressor jffs2_zstd_comp = {
> + .priority = JFFS2_ZSTD_PRIORITY,
> + .name = "zstd",
> + .compr = JFFS2_COMPR_ZSTD,
> + .compress = &jffs2_zstd_compress,
> + .decompress = &jffs2_zstd_decompress,
> + .disabled = 0,
> +};
> +
> +int __init jffs2_zstd_init(void)
> +{
> + int ret;
> +
> + ret = zstd_comp_init();
> + if (ret)
> + return ret;
> + ret = zstd_decomp_init();
> + if (ret)
> + zstd_comp_exit();
> + ret = jffs2_register_compressor(&jffs2_zstd_comp);
> + return ret;
> +}
> +
> +void jffs2_zstd_exit(void)
> +{
> + jffs2_unregister_compressor(&jffs2_zstd_comp);
> + zstd_comp_exit();
> + zstd_decomp_exit();
> +}
> diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
> index 81ca58c10b72..ddce95c55dde 100644
> --- a/fs/jffs2/super.c
> +++ b/fs/jffs2/super.c
> @@ -73,6 +73,10 @@ static const char *jffs2_compr_name(unsigned int compr)
> #ifdef CONFIG_JFFS2_ZLIB
> case JFFS2_COMPR_MODE_FORCEZLIB:
> return "zlib";
> +#endif
> +#ifdef CONFIG_JFFS2_ZSTD
> + case JFFS2_COMPR_MODE_FORCEZSTD:
> + return "zstd";
> #endif
> default:
> /* should never happen; programmer error */
> @@ -174,6 +178,9 @@ static const struct constant_table jffs2_param_compr[] = {
> #endif
> #ifdef CONFIG_JFFS2_ZLIB
> {"zlib", JFFS2_COMPR_MODE_FORCEZLIB },
> +#endif
> +#ifdef CONFIG_JFFS2_ZSTD
> + {"zstd", JFFS2_COMPR_MODE_FORCEZSTD },
> #endif
> {}
> };
> diff --git a/include/uapi/linux/jffs2.h b/include/uapi/linux/jffs2.h
> index 784ba0b9690a..af4fb69c8d69 100644
> --- a/include/uapi/linux/jffs2.h
> +++ b/include/uapi/linux/jffs2.h
> @@ -46,6 +46,7 @@
> #define JFFS2_COMPR_DYNRUBIN 0x05
> #define JFFS2_COMPR_ZLIB 0x06
> #define JFFS2_COMPR_LZO 0x07
> +#define JFFS2_COMPR_ZSTD 0x08
> /* Compatibility flags. */
> #define JFFS2_COMPAT_MASK 0xc000 /* What do to if an unknown nodetype is found */
> #define JFFS2_NODE_ACCURATE 0x2000
> --
> 2.30.2
>

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