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

[Baruch Siach]

Hi Vineet,

On Thu, Jan 09, 2014 at 11:28:19AM +0530, Vineet Gupta wrote:
> 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.

Thanks for testing. Looking forward to your patch. It's needed for xtensa as 
well, I guess. I really wonder whether this !LFS is worth the trouble.  How 
much do you actually save when disabling LFS?

baruch

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