[PATCH v2] erofs-utils: support detecting maximum block size

[Kelvin Zhang]

Looks good to me, please merge this patch

On Thu, Jun 1, 2023 at 10:54 AM Gao Xiang <hsiangkao at linux.alibaba.com>
wrote:

> Previously PAGE_SIZE was actually unset for most cases so that it was
> always hard-coded 4096.
>
> In order to set EROFS_MAX_BLOCK_SIZE correctly, let's detect the real
> page size when configuring and get rid of PAGE_SIZE.
>
> Cc: Kelvin Zhang <zhangkelvin at google.com>
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> ---
> change since v1:
>  - get rid of PAGE_SIZE (Kelvin);
>
>  configure.ac             | 38 ++++++++++++++++++++++++++++++++++++++
>  include/erofs/internal.h | 10 ++--------
>  lib/namei.c              |  2 +-
>  mkfs/main.c              |  4 ++--
>  4 files changed, 43 insertions(+), 11 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 4dbe86f..2ade490 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -59,6 +59,8 @@ AC_DEFUN([EROFS_UTILS_PARSE_DIRECTORY],
>   fi
>  ])
>
> +AC_ARG_VAR([MAX_BLOCK_SIZE], [The maximum block size which erofs-utils
> supports])
> +
>  AC_ARG_ENABLE([debug],
>      [AS_HELP_STRING([--enable-debug],
>                      [enable debugging mode @<:@default=no@:>@])],
> @@ -202,6 +204,35 @@ AC_CHECK_FUNCS(m4_flatten([
>         tmpfile64
>         utimensat]))
>
> +# Detect maximum block size if necessary
> +AS_IF([test "x$MAX_BLOCK_SIZE" = "x"], [
> +  AC_CACHE_CHECK([sysconf (_SC_PAGESIZE)], [erofs_cv_max_block_size],
> +               AC_RUN_IFELSE([AC_LANG_PROGRAM(
> +[[
> +#include <unistd.h>
> +#include <stdio.h>
> +]],
> +[[
> +    int result;
> +    FILE *f;
> +
> +    result = sysconf(_SC_PAGESIZE);
> +    if (result < 0)
> +       return 1;
> +
> +    f = fopen("conftest.out", "w");
> +    if (!f)
> +       return 1;
> +
> +    fprintf(f, "%d", result);
> +    fclose(f);
> +    return 0;
> +]])],
> +                             [erofs_cv_max_block_size=`cat conftest.out`],
> +                             [],
> +                             []))
> +], [erofs_cv_max_block_size=$MAX_BLOCK_SIZE])
> +
>  # Configure debug mode
>  AS_IF([test "x$enable_debug" != "xno"], [], [
>    dnl Turn off all assert checking.
> @@ -367,6 +398,13 @@ if test "x${have_liblzma}" = "xyes"; then
>    AC_SUBST([liblzma_CFLAGS])
>  fi
>
> +# Dump maximum block size
> +AS_IF([test "x$erofs_cv_max_block_size" = "x"],
> +      [$erofs_cv_max_block_size = 4096], [])
> +
> +AC_DEFINE_UNQUOTED([EROFS_MAX_BLOCK_SIZE], [$erofs_cv_max_block_size],
> +                  [The maximum block size which erofs-utils supports])
> +
>  AC_CONFIG_FILES([Makefile
>                  man/Makefile
>                  lib/Makefile
> diff --git a/include/erofs/internal.h b/include/erofs/internal.h
> index b3d04be..370cfac 100644
> --- a/include/erofs/internal.h
> +++ b/include/erofs/internal.h
> @@ -27,16 +27,10 @@ typedef unsigned short umode_t;
>  #define PATH_MAX        4096    /* # chars in a path name including nul */
>  #endif
>
> -#ifndef PAGE_SHIFT
> -#define PAGE_SHIFT             (12)
> +#ifndef EROFS_MAX_BLOCK_SIZE
> +#define EROFS_MAX_BLOCK_SIZE   4096
>  #endif
>
> -#ifndef PAGE_SIZE
> -#define PAGE_SIZE              (1U << PAGE_SHIFT)
> -#endif
> -
> -#define EROFS_MAX_BLOCK_SIZE   PAGE_SIZE
> -
>  #define EROFS_ISLOTBITS                5
>  #define EROFS_SLOTSIZE         (1U << EROFS_ISLOTBITS)
>
> diff --git a/lib/namei.c b/lib/namei.c
> index 3d0cf93..3751741 100644
> --- a/lib/namei.c
> +++ b/lib/namei.c
> @@ -137,7 +137,7 @@ int erofs_read_inode_from_disk(struct erofs_inode *vi)
>                 vi->u.chunkbits = sbi.blkszbits +
>                         (vi->u.chunkformat &
> EROFS_CHUNK_FORMAT_BLKBITS_MASK);
>         } else if (erofs_inode_is_data_compressed(vi->datalayout)) {
> -               if (erofs_blksiz() != PAGE_SIZE)
> +               if (erofs_blksiz() != EROFS_MAX_BLOCK_SIZE)
>                         return -EOPNOTSUPP;
>                 return z_erofs_fill_inode(vi);
>         }
> diff --git a/mkfs/main.c b/mkfs/main.c
> index 3ec4903..a6a2d0e 100644
> --- a/mkfs/main.c
> +++ b/mkfs/main.c
> @@ -532,7 +532,7 @@ static int mkfs_parse_options_cfg(int argc, char
> *argv[])
>                 cfg.c_dbg_lvl = EROFS_ERR;
>                 cfg.c_showprogress = false;
>         }
> -       if (cfg.c_compr_alg[0] && erofs_blksiz() != PAGE_SIZE) {
> +       if (cfg.c_compr_alg[0] && erofs_blksiz() != EROFS_MAX_BLOCK_SIZE) {
>                 erofs_err("compression is unsupported for now with block
> size %u",
>                           erofs_blksiz());
>                 return -EINVAL;
> @@ -670,7 +670,7 @@ static void erofs_mkfs_default_options(void)
>  {
>         cfg.c_showprogress = true;
>         cfg.c_legacy_compress = false;
> -       sbi.blkszbits = ilog2(PAGE_SIZE);
> +       sbi.blkszbits = ilog2(EROFS_MAX_BLOCK_SIZE);
>         sbi.feature_incompat = EROFS_FEATURE_INCOMPAT_LZ4_0PADDING;
>         sbi.feature_compat = EROFS_FEATURE_COMPAT_SB_CHKSUM |
>                              EROFS_FEATURE_COMPAT_MTIME;
> --
> 2.24.4
>
>

-- 
Sincerely,

Kelvin Zhang
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