[PATCH v2] linux: posix_fadvise: restore implementation for xtensa

[Vineet Gupta]

Hi Baruch,

On Sunday 05 January 2014 03:14 PM, Baruch Siach wrote:
> Commit ee84b8b400 (linux: posix_fadvise: use new SYSCALL_ALIGN_64BIT)
> removed posix_fadvise implementation for xtensa, since xtensa does not
> define __NR_fadvise64. Reuse the ARM support code to restore xtensa support.
> 
> This commit is based Mike Frysinger's suggested patch.
> 
> Cc: Mike Frysinger <vapier at gentoo.org>
> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> ---
> v2: Use Mike's approach, v1 was broken
> ---
>  libc/sysdeps/linux/common/posix_fadvise.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/libc/sysdeps/linux/common/posix_fadvise.c b/libc/sysdeps/linux/common/posix_fadvise.c
> index e102ce7afe31..25c294178e5e 100644
> --- a/libc/sysdeps/linux/common/posix_fadvise.c
> +++ b/libc/sysdeps/linux/common/posix_fadvise.c
> @@ -10,18 +10,25 @@
>  
>  #include <sys/syscall.h>
>  
> -#if defined(__NR_fadvise64) || defined(__NR_arm_fadvise64_64)
> +#ifdef __NR_arm_fadvise64_64
> +/* We handle the 64bit alignment issue which is why the arm guys renamed their
> + * syscall in the first place.  So rename it back.
> + */
> +# define __NR_fadvise64_64 __NR_arm_fadvise64_64
> +#endif
> +
> +#if defined(__NR_fadvise64) || defined(__NR_fadvise64_64)
>  # include <fcntl.h>
>  # include <endian.h>
>  # include <bits/wordsize.h>
>  
> -# ifdef __NR_arm_fadvise64_64
> +# ifdef __NR_fadvise64_64
>  int posix_fadvise64(int fd, off64_t offset, off64_t len, int advice);
>  # endif
>  
>  int posix_fadvise(int fd, off_t offset, off_t len, int advice)
>  {
> -# ifdef __NR_arm_fadvise64_64
> +# ifdef __NR_fadvise64_64
>  	return posix_fadvise64(fd, offset, len, advice);
>  # else
>  	int ret;
> @@ -41,7 +48,7 @@ int posix_fadvise(int fd, off_t offset, off_t len, int advice)
>  	return 0;
>  #  endif
>  }
> -# if defined __UCLIBC_HAS_LFS__ && ((!defined __NR_fadvise64_64 && !defined __NR_arm_fadvise64_64) || __WORDSIZE == 64)
> +# if defined __UCLIBC_HAS_LFS__ && (!defined __NR_fadvise64_64 || __WORDSIZE == 64)
>  strong_alias(posix_fadvise,posix_fadvise64)
>  # endif
>  #endif
> 

Thx for this fix, it unborks e2fsprogs build for ARC. However this doesn't build
for !LFS. It seems !LFS breakage was introduced with 347567313 "add
posix_fadvise() for arm" and confined only to ARM. Now that everyone uses same
code, the damage is noticeable elsewhere too.

The twist now is that, arches such as ARC/METAG are "no-legacy-syscalls-kernel ABI
- so we only have __NR_fadvise64_64 (even for !LFS)

I'll try to come up with a patch later today but just wanted to bring this to
attention anyways.

-Vineet