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Re: [PATCH v3 2/2] posix: Implement preadv2 and pwritev2


Ping.

On 04/05/2017 09:43, Adhemerval Zanella wrote:
> Change from previous version:
> 
>    * Add unsupported flag check for Linux implementation.
> 
>    * Unsupported/invalid flags now return EOPNOTSUPP instead of
>      EINVAL.
> 
>    * Add comment about preadv2 and pwritev2 support on kernel-features.h.
> 
>    * Add NEWS entry.
> 
>    * Fix typo in documentation.
>         
> --
> 
> This patch adds support of preadv2 and pwritev2 which are similar to
> preadv/pwritev but adds an extra flag argument.  As for preadv/pwritev
> both interfaces are added a non-standard standard GNU API.
> 
> On default 'posix' implementation trying to emulate the Linux supported
> flags is troublesome:
> 
>    * We can not temporary change the file state of the O_DSYNC and O_SYNC
>      flags to emulate RWF_{D}SYNC (attempts to change the state of using
>      fcntl are silently ignored).
> 
>    * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
>      semantic not provided by any other flag (O_NONBLOCK for instance).
> 
> So default sysdeps/posix implementations fails with EINVAL for any non
> supported flag (which are none currently) calls generic preadv/pwritev.
> Basically, it supports only preadv2 called as preadv (with flags sets
> to 0).
> 
> The Linux one uses the preadv2/pwritev2 syscall if defined, otherwise it
> call preadv/writev.  Instead of using the previous __ASSUME_* to
> unconditionally issue the syscall (and avoid building the fallback routine),
> it call pread/write if the preadv2/pwritev2 syscalls fails.  The idea
> is just avoid adding another __ASSUME_* and checking each architecture
> on every kernel bump and simplify code conditionals.
> 
> Checked on x86_64-linux-gnu and on i686-linux-gnu and a check with
> run-built-tests=no on aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabihf,
> ia64-linux-gnu, m68k-linux-gnu, microblaze-linux-gnu, mips{64,64n32}-linux-gnu,
> nios2-linux-gnu, powerpc{64,64le}-linux-gnu, s390{x}-linux-gnu,
> sparc{64,v9}-linux-gnu, tile{gx,pro}-linux-gnu, and sh4-linux-gnu (all using
> gcc 6.3).
> 
> 	* NEWS: Add note about pwritev2 and preadv2 inclusion.
> 	* misc/Makefile (routines): Add preadv2, preadv64v2, pwritev2, and
> 	pwritev64v2.
> 	(tests): Add tst-preadvwritev2 and tst-preadvwritev64v2.
> 	* misc/Versions (GLIBC_2.26): Add preadv2, preadv64v2, pwritev2, and
> 	pwritev64v2.
> 	* misc/preadv2.c: New file.
> 	* misc/preadv64v2.c: Likewise.
> 	* misc/pwritev2.c: Likewise.
> 	* misc/pwritev64v2.c: Likewise.
> 	* misc/tst-preadvwritev2.c: Likewise.
> 	* misc/tst-preadvwritev64v2.c: Likewise.
> 	* manual/llio.texi: Add preadv2 and pwritev2 documentation.
> 	* misc/sys/uio.h [__USE_GNU && !__USE_FILE_OFFSET64] (preadv2): New
> 	prototype.
> 	[__USE_GNU && !__USE_FILE_OFFSET64] (pwritev2):	Likewise.
> 	[__USE_GNU && __USE_FILE_OFFSET64] (preadv64v2): Likewise.
> 	[__USE_GNU && __USE_FILE_OFFSET64] (pwritev64v2): Likewise.
> 	* misc/tst-preadvwritev-common.c (PREADV): Define if not defined.
> 	(PWRITEV): Likewise.
> 	(do_test_with_offset): Use PREADV and PWRITEV macros and check for
> 	ENOSYS.
> 	* nptl/tst-cancel4.c (tf_pwritev2): New test.
> 	(tf_preadv2): Likewise.
> 	(tf_fsync): Add tf_pwritev2 and tf_preadv2.
> 	* sysdeps/posix/preadv2.c: Likewise.
> 	* sysdeps/posix/preadv64v2.c: Likewise.
> 	* sysdeps/posix/pwritev2.c: Likewise.
> 	* sysdeps/posix/pwritev64v2.c: Likewise.
> 	* sysdeps/unix/sysv/linux/kernel-features.h: Add comment for syscall
> 	support in kernel.
> 	* sysdeps/unix/sysv/linux/preadv2.c: Likewise.
> 	* sysdeps/unix/sysv/linux/preadv64v2.c: Likewise.
> 	* sysdeps/unix/sysv/linux/pwritev2.c: Likewise.
> 	* sysdeps/unix/sysv/linux/pwritev64v2.c: Likewise.
> 	* sysdeps/unix/sysv/linux/preadv.c (preadv): Add libc_hidden_def.
> 	* sysdeps/unix/sysv/linux/preadv64.c (preadv64): Likewise.
> 	* sysdeps/unix/sysv/linux/pwritev.c (pwritev): Likewise.
> 	* sysdeps/unix/sysv/linux/pwritev64.c (pwritev64): Likewise.
> 	* sysdeps/unix/sysv/linux/bits/uio.h: Add supported preadv2/pwritev2
> 	support flags on Linux.
> 	* sysdeps/unix/sysv/linux/aarch64/libc.abilist (GLIBC_2.26): Add
> 	preadv2, preadv64v2, pwritev2, pwritev64v2.
> 	* sysdeps/unix/sysv/linux/alpha/libc.abilist (GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/arm/libc.abilist (GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/hppa/libc.abilist (GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/libc.abilist (GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/ia64/libc.abilist (GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/microblaze/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/nios2/libc.abilist (GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> 	(GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> 	(GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
> 	(GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/sh/libc.abilist (GLIBC_2.26): Likewise.
> 	* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/sysv/linux/tile/tilegx/tilegx32/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/sysv/linux/tile/tilegx/tilegx64/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist (GLIBC_2.26):
> 	Likewise.
> 	* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist (GLIBC_2.26):
> 	Likewise.
> ---
>  ChangeLog                                          |  91 +++++++++++++++++
>  NEWS                                               |   7 ++
>  include/sys/uio.h                                  |   6 ++
>  manual/llio.texi                                   | 109 +++++++++++++++++++++
>  misc/Makefile                                      |   5 +-
>  misc/Versions                                      |   3 +
>  misc/preadv2.c                                     |  30 ++++++
>  misc/preadv64v2.c                                  |  30 ++++++
>  misc/pwritev2.c                                    |  30 ++++++
>  misc/pwritev64v2.c                                 |  30 ++++++
>  misc/sys/uio.h                                     |  41 ++++++++
>  misc/tst-preadvwritev-common.c                     |  19 +++-
>  misc/tst-preadvwritev2.c                           |  31 ++++++
>  misc/tst-preadvwritev64v2.c                        |  33 +++++++
>  nptl/tst-cancel4.c                                 |  71 ++++++++++++++
>  sysdeps/posix/preadv2.c                            |  38 +++++++
>  sysdeps/posix/preadv64v2.c                         |  37 +++++++
>  sysdeps/posix/pwritev2.c                           |  38 +++++++
>  sysdeps/posix/pwritev64v2.c                        |  38 +++++++
>  sysdeps/unix/sysv/linux/aarch64/libc.abilist       |   5 +
>  sysdeps/unix/sysv/linux/alpha/libc.abilist         |   5 +
>  sysdeps/unix/sysv/linux/arm/libc.abilist           |   5 +
>  sysdeps/unix/sysv/linux/bits/uio.h                 |   6 ++
>  sysdeps/unix/sysv/linux/hppa/libc.abilist          |   5 +
>  sysdeps/unix/sysv/linux/i386/libc.abilist          |   5 +
>  sysdeps/unix/sysv/linux/ia64/libc.abilist          |   5 +
>  sysdeps/unix/sysv/linux/kernel-features.h          |   5 +
>  sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist |   5 +
>  sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist   |   5 +
>  sysdeps/unix/sysv/linux/microblaze/libc.abilist    |   5 +
>  .../unix/sysv/linux/mips/mips32/fpu/libc.abilist   |   5 +
>  .../unix/sysv/linux/mips/mips32/nofpu/libc.abilist |   5 +
>  .../unix/sysv/linux/mips/mips64/n32/libc.abilist   |   5 +
>  .../unix/sysv/linux/mips/mips64/n64/libc.abilist   |   5 +
>  sysdeps/unix/sysv/linux/nios2/libc.abilist         |   5 +
>  .../sysv/linux/powerpc/powerpc32/fpu/libc.abilist  |   5 +
>  .../linux/powerpc/powerpc32/nofpu/libc.abilist     |   5 +
>  .../sysv/linux/powerpc/powerpc64/libc-le.abilist   |   5 +
>  .../unix/sysv/linux/powerpc/powerpc64/libc.abilist |   5 +
>  sysdeps/unix/sysv/linux/preadv.c                   |   2 +
>  sysdeps/unix/sysv/linux/preadv2.c                  |  55 +++++++++++
>  sysdeps/unix/sysv/linux/preadv64.c                 |   2 +
>  sysdeps/unix/sysv/linux/preadv64v2.c               |  55 +++++++++++
>  sysdeps/unix/sysv/linux/pwrite64.c                 |   1 +
>  sysdeps/unix/sysv/linux/pwritev.c                  |   2 +
>  sysdeps/unix/sysv/linux/pwritev2.c                 |  51 ++++++++++
>  sysdeps/unix/sysv/linux/pwritev64.c                |   2 +
>  sysdeps/unix/sysv/linux/pwritev64v2.c              |  55 +++++++++++
>  sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist  |   5 +
>  sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist  |   5 +
>  sysdeps/unix/sysv/linux/sh/libc.abilist            |   5 +
>  sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist |   5 +
>  sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist |   5 +
>  .../sysv/linux/tile/tilegx/tilegx32/libc.abilist   |   5 +
>  .../sysv/linux/tile/tilegx/tilegx64/libc.abilist   |   5 +
>  sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist  |   5 +
>  sysdeps/unix/sysv/linux/x86_64/64/libc.abilist     |   5 +
>  sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist    |   5 +
>  58 files changed, 1058 insertions(+), 5 deletions(-)
>  create mode 100644 misc/preadv2.c
>  create mode 100644 misc/preadv64v2.c
>  create mode 100644 misc/pwritev2.c
>  create mode 100644 misc/pwritev64v2.c
>  create mode 100644 misc/tst-preadvwritev2.c
>  create mode 100644 misc/tst-preadvwritev64v2.c
>  create mode 100644 sysdeps/posix/preadv2.c
>  create mode 100644 sysdeps/posix/preadv64v2.c
>  create mode 100644 sysdeps/posix/pwritev2.c
>  create mode 100644 sysdeps/posix/pwritev64v2.c
>  create mode 100644 sysdeps/unix/sysv/linux/preadv2.c
>  create mode 100644 sysdeps/unix/sysv/linux/preadv64v2.c
>  create mode 100644 sysdeps/unix/sysv/linux/pwritev2.c
>  create mode 100644 sysdeps/unix/sysv/linux/pwritev64v2.c
> 
> diff --git a/NEWS b/NEWS
> index 5558ca3..afad4b1 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -57,6 +57,13 @@ Version 2.26
>    be added on next major revision of POSIX, so current support is enabled
>    with _GNU_SOURCE.
>  
> +* New preadv2 and pwritev2 are added to libc.  They are Linux extensions to
> +  preadv and pwritev with an additional flag argument where it is possible
> +  to set high priority or use O_DSYNC or O_SYNC for an specific IO operation.
> +  For complete support it requires Linux kernel version 4.6, otherwise a
> +  compat implementation will be used (which refuses all flags and routes it
> +  to preadv or pwritev).
> +
>  Security related changes:
>  
>  * The DNS stub resolver limits the advertised UDP buffer size to 1200 bytes,
> diff --git a/include/sys/uio.h b/include/sys/uio.h
> index f44ce18..20860bf 100644
> --- a/include/sys/uio.h
> +++ b/include/sys/uio.h
> @@ -7,5 +7,11 @@ extern ssize_t __readv (int __fd, const struct iovec *__iovec,
>  			int __count);
>  extern ssize_t __writev (int __fd, const struct iovec *__iovec,
>  			 int __count);
> +
> +/* Used for p{read,write}{v64}v2 implementation.  */
> +libc_hidden_proto (preadv)
> +libc_hidden_proto (preadv64)
> +libc_hidden_proto (pwritev)
> +libc_hidden_proto (pwritev64)
>  #endif
>  #endif
> diff --git a/manual/llio.texi b/manual/llio.texi
> index dae3754..404a966 100644
> --- a/manual/llio.texi
> +++ b/manual/llio.texi
> @@ -756,6 +756,115 @@ When the source file is compiled using @code{_FILE_OFFSET_BITS == 64} on a
>  @code{pwritev} and so transparently replaces the 32 bit interface.
>  @end deftypefun
>  
> +@comment sys/uio.h
> +@comment GNU
> +@deftypefun ssize_t preadv2 (int @var{fd}, const struct iovec *@var{iov}, int @var{iovcnt}, off_t @var{offset}, int @var{flags})
> +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
> +@c This is a syscall for Linux v4.6.  The sysdeps/posix fallback emulation
> +@c is also MT-Safe since it calls preadv.
> +
> +This function is similar to the @code{preadv} function, with the difference
> +it adds an extra @var{flags} parameter of type @code{int}.  The supported
> +@var{flags} are dependent of the underlying system.  For Linux it supports:
> +
> +@vtable @code
> +@item RWF_HIPRI
> +High priority request.  This adds a flag that tells the file system that
> +this is a high priority request for which it is worth to poll the hardware.
> +The flag is purely advisory and can be ignored if not supported.  The
> +@var{fd} must be opened using @code{O_DIRECT}.
> +
> +@item RWF_DSYNC
> +Per-IO synchronization as if the file was opened with @code{O_DSYNC} flag.
> +
> +@item RWF_SYNC
> +Per-IO synchronization as if the file was opened with @code{O_SYNC} flag.
> +@end vtable
> +
> +When the source file is compiled with @code{_FILE_OFFSET_BITS == 64} the
> +@code{preadv2} function is in fact @code{preadv64v2} and the type
> +@code{off_t} has 64 bits, which makes it possible to handle files up to
> +@twoexp{63} bytes in length.
> +
> +The return value is a count of bytes (@emph{not} buffers) read, @math{0}
> +indicating end-of-file, or @math{-1} indicating an error.  The possible
> +errors are the same as in @code{preadv} with the addition of:
> +
> +@table @code
> +
> +@item EOPNOTSUPP
> +
> +@c The default sysdeps/posix code will return it for any flags value
> +@c different than 0.
> +An unsupported @var{flags} was used.
> +
> +@end table
> +
> +@end deftypefun
> +
> +@comment unistd.h
> +@comment GNU
> +@deftypefun ssize_t preadv64v2 (int @var{fd}, const struct iovec *@var{iov}, int @var{iovcnt}, off64_t @var{offset}, int @var{flags})
> +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
> +@c This is a syscall for Linux v4.6.  The sysdeps/posix fallback emulation
> +@c is also MT-Safe since it calls preadv.
> +
> +This function is similar to the @code{preadv2} function with the difference
> +is that the @var{offset} parameter is of type @code{off64_t} instead of
> +@code{off_t}.  It makes it possible on 32 bit machines to address
> +files larger than @twoexp{31} bytes and up to @twoexp{63} bytes.  The
> +file descriptor @code{filedes} must be opened using @code{open64} since
> +otherwise the large offsets possible with @code{off64_t} will lead to
> +errors with a descriptor in small file mode.
> +
> +When the source file is compiled using @code{_FILE_OFFSET_BITS == 64} on a
> +32 bit machine this function is actually available under the name
> +@code{preadv2} and so transparently replaces the 32 bit interface.
> +@end deftypefun
> +
> +
> +@comment sys/uio.h
> +@comment GNU
> +@deftypefun ssize_t pwritev2 (int @var{fd}, const struct iovec *@var{iov}, int @var{iovcnt}, off_t @var{offset}, int @var{flags})
> +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
> +@c This is a syscall for Linux v4.6.  The sysdeps/posix fallback emulation
> +@c is also MT-Safe since it calls pwritev.
> +
> +This function is similar to the @code{pwritev} function, with the difference
> +it adds an extra @var{flags} parameter of type @code{int}.  The supported
> +@var{flags} are dependent of the underlying system and for Linux it supports
> +the same ones as for @code{preadv2}.
> +
> +When the source file is compiled with @code{_FILE_OFFSET_BITS == 64} the
> +@code{pwritev2} function is in fact @code{pwritev64v2} and the type
> +@code{off_t} has 64 bits, which makes it possible to handle files up to
> +@twoexp{63} bytes in length.
> +
> +The return value is a count of bytes (@emph{not} buffers) write, @math{0}
> +indicating end-of-file, or @math{-1} indicating an error.  The possible
> +errors are the same as in @code{preadv2}.
> +@end deftypefun
> +
> +@comment unistd.h
> +@comment GNU
> +@deftypefun ssize_t pwritev64v2 (int @var{fd}, const struct iovec *@var{iov}, int @var{iovcnt}, off64_t @var{offset}, int @var{flags})
> +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
> +@c This is a syscall for Linux v4.6.  The sysdeps/posix fallback emulation
> +@c is also MT-Safe since it calls pwritev.
> +
> +This function is similar to the @code{pwritev2} function with the difference
> +is that the @var{offset} parameter is of type @code{off64_t} instead of
> +@code{off_t}.  It makes it possible on 32 bit machines to address
> +files larger than @twoexp{31} bytes and up to @twoexp{63} bytes.  The
> +file descriptor @code{filedes} must be opened using @code{open64} since
> +otherwise the large offsets possible with @code{off64_t} will lead to
> +errors with a descriptor in small file mode.
> +
> +When the source file is compiled using @code{_FILE_OFFSET_BITS == 64} on a
> +32 bit machine this function is actually available under the name
> +@code{pwritev2} and so transparently replaces the 32 bit interface.
> +@end deftypefun
> +
>  
>  @node File Position Primitive
>  @section Setting the File Position of a Descriptor
> diff --git a/misc/Makefile b/misc/Makefile
> index 622da67..bed46d7 100644
> --- a/misc/Makefile
> +++ b/misc/Makefile
> @@ -39,6 +39,7 @@ headers	:= sys/uio.h bits/uio.h sys/ioctl.h bits/ioctls.h bits/ioctl-types.h \
>  
>  routines := brk sbrk sstk ioctl \
>  	    readv writev preadv preadv64 pwritev pwritev64 \
> +	    preadv2 preadv64v2 pwritev2 pwritev64v2 \
>  	    setreuid setregid \
>  	    seteuid setegid \
>  	    getpagesize \
> @@ -79,7 +80,9 @@ gpl2lgpl := error.c error.h
>  tests := tst-dirname tst-tsearch tst-fdset tst-efgcvt tst-mntent tst-hsearch \
>  	 tst-error1 tst-pselect tst-insremque tst-mntent2 bug-hsearch1 \
>  	 tst-mntent-blank-corrupt tst-mntent-blank-passno bug18240 \
> -	 tst-preadvwritev tst-preadvwritev64 tst-makedev tst-empty \
> +	 tst-preadvwritev tst-preadvwritev64 tst-preadvwritev2 \
> +	 tst-preadvwritev64v2 \
> +	 tst-makedev tst-empty \
>  	 tst-atomic tst-atomic-long
>  tests-static := tst-empty
>  
> diff --git a/misc/Versions b/misc/Versions
> index f2c90ff..bafda78 100644
> --- a/misc/Versions
> +++ b/misc/Versions
> @@ -155,6 +155,9 @@ libc {
>    GLIBC_2.25 {
>      gnu_dev_major; gnu_dev_minor; gnu_dev_makedev;
>    }
> +  GLIBC_2.26 {
> +    preadv2; preadv64v2; pwritev2; pwritev64v2;
> +  }
>    GLIBC_PRIVATE {
>      __madvise;
>      __mktemp;
> diff --git a/misc/preadv2.c b/misc/preadv2.c
> new file mode 100644
> index 0000000..a62dcaa
> --- /dev/null
> +++ b/misc/preadv2.c
> @@ -0,0 +1,30 @@
> +/* Default implementation of preadv2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +
> +/* Same as preadv but with an additional flags argument.  */
> +ssize_t
> +preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
> +	 int flags)
> +{
> +  __set_errno (ENOSYS);
> +  return -1;
> +}
> +
> +stub_warning (preadv2)
> diff --git a/misc/preadv64v2.c b/misc/preadv64v2.c
> new file mode 100644
> index 0000000..a802c2f
> --- /dev/null
> +++ b/misc/preadv64v2.c
> @@ -0,0 +1,30 @@
> +/* Default implementation of preadv2 (LFS version).
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +
> +/* Same as preadv64 but with an addional flag argument.  */
> +ssize_t
> +preadv64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> +	    int flags)
> +{
> +  __set_errno (ENOSYS);
> +  return -1;
> +}
> +
> +stub_warning (preadv64v2)
> diff --git a/misc/pwritev2.c b/misc/pwritev2.c
> new file mode 100644
> index 0000000..b9e0727
> --- /dev/null
> +++ b/misc/pwritev2.c
> @@ -0,0 +1,30 @@
> +/* Default implementation of pwritev2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +
> +/* Same as pwritev but with an additional flags argument.  */
> +ssize_t
> +pwritev2 (int fd, const struct iovec *vector, int count, off_t offset,
> +	  int flags)
> +{
> +  __set_errno (ENOSYS);
> +  return -1;
> +}
> +
> +stub_warning (pwritev2)
> diff --git a/misc/pwritev64v2.c b/misc/pwritev64v2.c
> new file mode 100644
> index 0000000..1f874f0
> --- /dev/null
> +++ b/misc/pwritev64v2.c
> @@ -0,0 +1,30 @@
> +/* Default implementation of pwritev2 (LFS version).
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +
> +/* Same as preadv64 but with an addional flag argument.  */
> +ssize_t
> +pwritev64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> +	     int flags)
> +{
> +  __set_errno (ENOSYS);
> +  return -1;
> +}
> +
> +stub_warning (pwritev64v2)
> diff --git a/misc/sys/uio.h b/misc/sys/uio.h
> index e80f013..66c22f0 100644
> --- a/misc/sys/uio.h
> +++ b/misc/sys/uio.h
> @@ -76,6 +76,7 @@ extern ssize_t preadv (int __fd, const struct iovec *__iovec, int __count,
>     __THROW.  */
>  extern ssize_t pwritev (int __fd, const struct iovec *__iovec, int __count,
>  			__off_t __offset) __wur;
> +
>  # else
>  #  ifdef __REDIRECT
>  extern ssize_t __REDIRECT (preadv, (int __fd, const struct iovec *__iovec,
> @@ -117,6 +118,46 @@ extern ssize_t pwritev64 (int __fd, const struct iovec *__iovec, int __count,
>  # endif
>  #endif	/* Use misc.  */
>  
> +
> +#ifdef __USE_GNU
> +# ifndef __USE_FILE_OFFSET64
> +/* Same as preadv but with an additional flag argumenti defined at uio.h.  */
> +extern ssize_t preadv2 (int __fp, const struct iovec *__iovec, int __count,
> +			__off_t __offset, int ___flags) __wur;
> +
> +/* Same as preadv but with an additional flag argument defined at uio.h.  */
> +extern ssize_t pwritev2 (int __fd, const struct iovec *__iodev, int __count,
> +			 __off_t __offset, int __flags) __wur;
> +
> +# else
> +#  ifdef __REDIRECT
> +extern ssize_t __REDIRECT (pwritev2, (int __fd, const struct iovec *__iovec,
> +				      int __count, __off64_t __offset,
> +				      int __flags),
> +			   pwritev64v2) __wur;
> +extern ssize_t __REDIRECT (preadv2, (int __fd, const struct iovec *__iovec,
> +				     int __count, __off64_t __offset,
> +				     int __flags),
> +			   preadv64v2) __wur;
> +#  else
> +#   define preadv2 preadv64v2
> +#   define pwritev2 pwritev64v2
> +#  endif
> +# endif
> +
> +# ifdef __USE_LARGEFILE64
> +/* Same as preadv but with an additional flag argumenti defined at uio.h.  */
> +extern ssize_t preadv64v2 (int __fp, const struct iovec *__iovec,
> +			   int __count, __off64_t __offset,
> +			   int ___flags) __wur;
> +
> +/* Same as preadv but with an additional flag argument defined at uio.h.  */
> +extern ssize_t pwritev64v2 (int __fd, const struct iovec *__iodev,
> +			    int __count, __off64_t __offset,
> +			    int __flags) __wur;
> +# endif
> +#endif /* Use GNU.  */
> +
>  __END_DECLS
>  
>  #endif /* sys/uio.h */
> diff --git a/misc/tst-preadvwritev-common.c b/misc/tst-preadvwritev-common.c
> index 5540dfb..676d495 100644
> --- a/misc/tst-preadvwritev-common.c
> +++ b/misc/tst-preadvwritev-common.c
> @@ -18,6 +18,7 @@
>  
>  #include <stdio.h>
>  #include <stdint.h>
> +#include <errno.h>
>  #include <string.h>
>  #include <sys/uio.h>
>  #include <sys/stat.h>
> @@ -39,6 +40,16 @@ do_prepare (int argc, char **argv)
>  }
>  #define PREPARE do_prepare
>  
> +#ifndef PREADV
> +# define PREADV(__fd, __iov, __iovcnt, __offset) \
> +  preadv (__fd, __iov, __iovcnt, __offset)
> +#endif
> +
> +#ifndef PWRITEV
> +# define PWRITEV(__fd, __iov, __iovcnt, __offset) \
> +  pwritev (__fd, __iov, __iovcnt, __offset)
> +#endif
> +
>  static int
>  do_test_with_offset (off_t offset)
>  {
> @@ -58,13 +69,13 @@ do_test_with_offset (off_t offset)
>    iov[1].iov_base = buf2;
>    iov[1].iov_len = sizeof buf2;
>  
> -  ret = pwritev (temp_fd, iov, 2, offset);
> +  ret = PWRITEV (temp_fd, iov, 2, offset);
>    if (ret == -1)
>      FAIL_RET ("first pwritev returned -1");
>    if (ret != (sizeof buf1 + sizeof buf2))
>      FAIL_RET ("first pwritev returned an unexpected value");
>  
> -  ret = pwritev (temp_fd, iov, 2, sizeof buf1 + sizeof buf2 + offset);
> +  ret = PWRITEV (temp_fd, iov, 2, sizeof buf1 + sizeof buf2 + offset);
>    if (ret == -1)
>      FAIL_RET ("second pwritev returned -1");
>    if (ret != (sizeof buf1 + sizeof buf2))
> @@ -82,7 +93,7 @@ do_test_with_offset (off_t offset)
>    iov[1].iov_len = sizeof buf4;
>  
>    /* Now read two buffer with 32 and 64 bytes respectively.  */
> -  ret = preadv (temp_fd, iov, 2, offset);
> +  ret = PREADV (temp_fd, iov, 2, offset);
>    if (ret == -1)
>      FAIL_RET ("first preadv returned -1");
>    if (ret != (sizeof buf3 + sizeof buf4))
> @@ -93,7 +104,7 @@ do_test_with_offset (off_t offset)
>    if (memcmp (buf2, buf4, sizeof buf2) != 0)
>      FAIL_RET ("second buffer from first preadv different than expected");
>  
> -  ret = preadv (temp_fd, iov, 2, sizeof buf3 + sizeof buf4 + offset);
> +  ret = PREADV (temp_fd, iov, 2, sizeof buf3 + sizeof buf4 + offset);
>    if (ret == -1)
>      FAIL_RET ("second preadv returned -1");
>    if (ret != (sizeof buf3 + sizeof buf4))
> diff --git a/misc/tst-preadvwritev2.c b/misc/tst-preadvwritev2.c
> new file mode 100644
> index 0000000..cf36272
> --- /dev/null
> +++ b/misc/tst-preadvwritev2.c
> @@ -0,0 +1,31 @@
> +/* Tests for preadv2 and pwritev2.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#define PREADV(__fd, __iov, __iovcnt, __offset) \
> +  preadv2 (__fd, __iov, __iovcnt, __offset, 0)
> +
> +#define PWRITEV(__fd, __iov, __iovcnt, __offset) \
> +  pwritev2 (__fd, __iov, __iovcnt, __offset, 0)
> +
> +#include "tst-preadvwritev-common.c"
> +
> +static int
> +do_test (void)
> +{
> +  return do_test_with_offset (0);
> +}
> diff --git a/misc/tst-preadvwritev64v2.c b/misc/tst-preadvwritev64v2.c
> new file mode 100644
> index 0000000..8d0c48e
> --- /dev/null
> +++ b/misc/tst-preadvwritev64v2.c
> @@ -0,0 +1,33 @@
> +/* Tests for preadv2 and pwritev2 (LFS version).
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#define _FILE_OFFSET_BITS 64
> +
> +#define PREADV(__fd, __iov, __iovcnt, __offset) \
> +  preadv2 (__fd, __iov, __iovcnt, __offset, 0)
> +
> +#define PWRITEV(__fd, __iov, __iovcnt, __offset) \
> +  pwritev2 (__fd, __iov, __iovcnt, __offset, 0)
> +
> +#include "tst-preadvwritev-common.c"
> +
> +static int
> +do_test (void)
> +{
> +  return do_test_with_offset (0);
> +}
> diff --git a/nptl/tst-cancel4.c b/nptl/tst-cancel4.c
> index e66961f..7a560a1 100644
> --- a/nptl/tst-cancel4.c
> +++ b/nptl/tst-cancel4.c
> @@ -1079,6 +1079,75 @@ tf_pwritev (void *arg)
>  }
>  
>  static void *
> +tf_pwritev2 (void *arg)
> +{
> +  int fd;
> +
> +  if (arg == NULL)
> +    /* XXX If somebody can provide a portable test case in which pwritev2
> +       blocks we can enable this test to run in both rounds.  */
> +    abort ();
> +
> +  errno = 0;
> +
> +  char fname[] = "/tmp/tst-cancel4-fd-XXXXXX";
> +  tempfd = fd = mkstemp (fname);
> +  if (fd == -1)
> +    FAIL_EXIT1 ("mkstemp: %m");
> +  unlink (fname);
> +
> +  xpthread_barrier_wait (&b2);
> +
> +  xpthread_barrier_wait (&b2);
> +
> +  ssize_t s;
> +  pthread_cleanup_push (cl, NULL);
> +
> +  char buf[WRITE_BUFFER_SIZE];
> +  memset (buf, '\0', sizeof (buf));
> +  struct iovec iov[1] = { [0] = { .iov_base = buf, .iov_len = sizeof (buf) } };
> +  s = pwritev2 (fd, iov, 1, 0, 0);
> +
> +  pthread_cleanup_pop (0);
> +
> +  FAIL_EXIT1 ("pwritev2 returns with %zd", s);
> +}
> +
> +static void *
> +tf_preadv2 (void *arg)
> +{
> +  int fd;
> +
> +  if (arg == NULL)
> +    /* XXX If somebody can provide a portable test case in which preadv2
> +       blocks we can enable this test to run in both rounds.  */
> +    abort ();
> +
> +  errno = 0;
> +
> +  char fname[] = "/tmp/tst-cancel4-fd-XXXXXX";
> +  tempfd = fd = mkstemp (fname);
> +  if (fd == -1)
> +    FAIL_EXIT1 ("mkstemp failed: %m");
> +  unlink (fname);
> +
> +  xpthread_barrier_wait (&b2);
> +
> +  xpthread_barrier_wait (&b2);
> +
> +  ssize_t s;
> +  pthread_cleanup_push (cl, NULL);
> +
> +  char buf[100];
> +  struct iovec iov[1] = { [0] = { .iov_base = buf, .iov_len = sizeof (buf) } };
> +  s = preadv2 (fd, iov, 1, 0, 0);
> +
> +  pthread_cleanup_pop (0);
> +
> +  FAIL_EXIT1 ("preadv2 returns with %zd", s);
> +}
> +
> +static void *
>  tf_fsync (void *arg)
>  {
>    if (arg == NULL)
> @@ -1473,7 +1542,9 @@ struct cancel_tests tests[] =
>    ADD_TEST (recvfrom, 2, 0),
>    ADD_TEST (recvmsg, 2, 0),
>    ADD_TEST (preadv, 2, 1),
> +  ADD_TEST (preadv2, 2, 1),
>    ADD_TEST (pwritev, 2, 1),
> +  ADD_TEST (pwritev2, 2, 1),
>    ADD_TEST (open, 2, 1),
>    ADD_TEST (close, 2, 1),
>    ADD_TEST (pread, 2, 1),
> diff --git a/sysdeps/posix/preadv2.c b/sysdeps/posix/preadv2.c
> new file mode 100644
> index 0000000..2a7cf11
> --- /dev/null
> +++ b/sysdeps/posix/preadv2.c
> @@ -0,0 +1,38 @@
> +/* Generic version of preadv2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <unistd.h>
> +#include <sys/uio.h>
> +
> +#ifndef __OFF_T_MATCHES_OFF64_T
> +
> +/* Since we define no flags for preadv2 just route to preadv.  */
> +ssize_t
> +preadv2 (int fd, const struct iovec *vector, int count, OFF_T offset,
> +	 int flags)
> +{
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +
> +  return preadv (fd, vector, count, offset);
> +}
> +
> +#endif
> diff --git a/sysdeps/posix/preadv64v2.c b/sysdeps/posix/preadv64v2.c
> new file mode 100644
> index 0000000..e084f3f
> --- /dev/null
> +++ b/sysdeps/posix/preadv64v2.c
> @@ -0,0 +1,37 @@
> +/* Generic version of preadv2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <unistd.>
> +#include <sys/uio.h>
> +
> +ssize_t
> +preadv64v2 (int fd, const struct iovec *vector, int count, OFF_T offset,
> +	    int flags)
> +{
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +
> +  return preadv64 (fd, vector, count, offset);
> +}
> +
> +#ifdef __OFF_T_MATCHES_OFF64_T
> +strong_alias (preadv64v2, preadv2)
> +#endif
> diff --git a/sysdeps/posix/pwritev2.c b/sysdeps/posix/pwritev2.c
> new file mode 100644
> index 0000000..5b7650c
> --- /dev/null
> +++ b/sysdeps/posix/pwritev2.c
> @@ -0,0 +1,38 @@
> +/* Generic version of pwritev2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <unistd.h>
> +#include <sys/uio.h>
> +
> +#ifndef __OFF_T_MATCHES_OFF64_T
> +
> +/* Since we define no flags for pwritev2 just route to pwritev.  */
> +ssize_t
> +pwritev2 (int fd, const struct iovec *vector, int count, OFF_T offset,
> +	  int flags)
> +{
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +
> +  return pwritev (fd, vector, count, offset);
> +}
> +
> +#endif
> diff --git a/sysdeps/posix/pwritev64v2.c b/sysdeps/posix/pwritev64v2.c
> new file mode 100644
> index 0000000..d9727b9
> --- /dev/null
> +++ b/sysdeps/posix/pwritev64v2.c
> @@ -0,0 +1,38 @@
> +/* Generic version of pwritev2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <unistd.h>
> +#include <sys/uio.h>
> +
> +/* Since we define no flags for pwritev2 just route to pwritev.  */ 
> +ssize_t
> +pwritev64v2 (int fd, const struct iovec *vector, int count, OFF_T offset,
> +	     int flags)
> +{
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +
> +  return pwritev64 (fd, vector, count, offset);
> +}
> +
> +#ifdef __OFF_T_MATCHES_OFF64_T
> +strong_alias (pwritev64v2, pwritev2)
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> index 58d768c..296f2a5 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> @@ -2097,3 +2097,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
> index 906050d..8006e72 100644
> --- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
> @@ -2008,6 +2008,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
> index 66112dd..29f9688 100644
> --- a/sysdeps/unix/sysv/linux/arm/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
> @@ -98,6 +98,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.4 GLIBC_2.4 A
>  GLIBC_2.4 _Exit F
>  GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
> diff --git a/sysdeps/unix/sysv/linux/bits/uio.h b/sysdeps/unix/sysv/linux/bits/uio.h
> index 1583f04..d5701f8 100644
> --- a/sysdeps/unix/sysv/linux/bits/uio.h
> +++ b/sysdeps/unix/sysv/linux/bits/uio.h
> @@ -69,4 +69,10 @@ extern ssize_t process_vm_writev (pid_t __pid, const struct iovec *__lvec,
>  __END_DECLS
>  
>  # endif
> +
> +/* Flags for preadv2/pwritev2: */
> +#define RWF_HIPRI	0x00000001 /* High priority request.  */
> +#define RWF_DSYNC	0x00000002 /* per-IO O_DSYNC.  */
> +#define RWF_SYNC	0x00000004 /* per-IO O_SYNC.  */
> +
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
> index 3ddadd2..e9cfbaf 100644
> --- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
> @@ -1862,6 +1862,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
> index 977ab90..c6ad3c3 100644
> --- a/sysdeps/unix/sysv/linux/i386/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
> @@ -2020,6 +2020,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
> index c7edb9a..d0055a2 100644
> --- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
> @@ -1884,6 +1884,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
> index b981466..8ee1af7 100644
> --- a/sysdeps/unix/sysv/linux/kernel-features.h
> +++ b/sysdeps/unix/sysv/linux/kernel-features.h
> @@ -137,3 +137,8 @@
>  /* Support for SysV IPC through wired syscalls.  All supported architectures
>     either support ipc syscall and/or all the ipc correspondent syscalls.  */
>  #define __ASSUME_DIRECT_SYSVIPC_SYSCALLS	1
> +
> +/* Support for p{read,write}v2 was added in 4.6.  However Linux default
> +   implementation does not assume the __ASSUME_* and instead use a fallback
> +   implementation based on p{read,write}v and returning an error for
> +   non supported flags.  */
> diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> index 450be4e..3777676 100644
> --- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
> @@ -99,6 +99,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.4 GLIBC_2.4 A
>  GLIBC_2.4 _Exit F
>  GLIBC_2.4 _IO_2_1_stderr_ D 0x98
> diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> index 9e016bd..8b1f80c 100644
> --- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
> @@ -1976,6 +1976,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/microblaze/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
> index 1a455be..d4db9a8 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
> @@ -2097,3 +2097,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> index 8eb5e66..f430bdb 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
> @@ -1951,6 +1951,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> index 416d9ac..a4dca19 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
> @@ -1949,6 +1949,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> index f4949e5..0814fa8 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
> @@ -1947,6 +1947,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> index c7375ae..a0bdeff 100644
> --- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
> @@ -1942,6 +1942,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
> index 724a0e3..b201290 100644
> --- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
> @@ -2138,3 +2138,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> index 2dc32b6..6e7ff24 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
> @@ -1980,6 +1980,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> index 5658109..19c7c7d 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
> @@ -1985,6 +1985,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
> index c761221..e94ce38 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
> @@ -2185,3 +2185,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
> index 265c769..f3daa33 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
> @@ -99,6 +99,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 _Exit F
>  GLIBC_2.3 _IO_2_1_stderr_ D 0xe0
> diff --git a/sysdeps/unix/sysv/linux/preadv.c b/sysdeps/unix/sysv/linux/preadv.c
> index 7d971cc..ecabc8c 100644
> --- a/sysdeps/unix/sysv/linux/preadv.c
> +++ b/sysdeps/unix/sysv/linux/preadv.c
> @@ -50,4 +50,6 @@ preadv (int fd, const struct iovec *vector, int count, off_t offset)
>  #  define OFF_T off_t
>  #  include <sysdeps/posix/preadv_common.c>
>  # endif /* __ASSUME_PREADV  */
> +
> +libc_hidden_def (preadv)
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/preadv2.c b/sysdeps/unix/sysv/linux/preadv2.c
> new file mode 100644
> index 0000000..11fe85e
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/preadv2.c
> @@ -0,0 +1,55 @@
> +/* Linux implementation of preadv2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +#include <sysdep-cancel.h>
> +
> +#ifndef __OFF_T_MATCHES_OFF64_T
> +
> +# if !defined (__NR_preadv2) && defined (__NR_pread64v2)
> +#  define __NR_preadv2 __NR_pread64v2
> +# endif
> +
> +ssize_t
> +preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
> +	 int flags)
> +{
> +# ifdef __NR_preadv2
> +  ssize_t result = SYSCALL_CANCEL (preadv2, fd, vector, count,
> +				   LO_HI_LONG (offset), flags);
> +  if (result >= 0 || errno != ENOSYS)
> +    return result;
> +# endif
> +  /* Trying to emulate the preadv2 syscall flags is troublesome:
> +
> +     * We can not temporary change the file state of the O_DSYNC and O_SYNC
> +       flags to emulate RWF_{D}SYNC (attempts to change the state of using
> +       fcntl are silently ignored).
> +
> +     * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
> +       semantic not provided by any other flag (O_NONBLOCK for instance).  */
> +
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +  return preadv (fd, vector, count, offset);
> +}
> +
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/preadv64.c b/sysdeps/unix/sysv/linux/preadv64.c
> index 66daa74..c96b214 100644
> --- a/sysdeps/unix/sysv/linux/preadv64.c
> +++ b/sysdeps/unix/sysv/linux/preadv64.c
> @@ -48,7 +48,9 @@ preadv64 (int fd, const struct iovec *vector, int count, off64_t offset)
>  # define OFF_T off64_t
>  # include <sysdeps/posix/preadv_common.c>
>  #endif
> +libc_hidden_def (preadv64)
>  
>  #ifdef __OFF_T_MATCHES_OFF64_T
>  strong_alias (preadv64, preadv)
> +libc_hidden_def (preadv)
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/preadv64v2.c b/sysdeps/unix/sysv/linux/preadv64v2.c
> new file mode 100644
> index 0000000..9d7f8c9
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/preadv64v2.c
> @@ -0,0 +1,55 @@
> +/* Linux implementation of preadv2 (LFS version).
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +#include <sysdep-cancel.h>
> +
> +#if !defined(__NR_preadv64v2) && defined(__NR_preadv2)
> +# define __NR_preadv64v2 __NR_preadv2
> +#endif
> +
> +ssize_t
> +preadv64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> +	    int flags)
> +{
> +#ifdef __NR_preadv64v2
> +  ssize_t result = SYSCALL_CANCEL (preadv64v2, fd, vector, count,
> +				   LO_HI_LONG (offset), flags);
> +  if (result >= 0 || errno != ENOSYS)
> +    return result;
> +#endif
> +  /* Trying to emulate the preadv2 syscall flags is troublesome:
> +
> +     * We can not temporary change the file state of the O_DSYNC and O_SYNC
> +       flags to emulate RWF_{D}SYNC (attempts to change the state of using
> +       fcntl are silently ignored).
> +
> +     * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
> +       semantic not provided by any other flag (O_NONBLOCK for instance).  */
> +
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +  return preadv64 (fd, vector, count, offset);
> +}
> +
> +#ifdef __OFF_T_MATCHES_OFF64_T
> +strong_alias (preadv64v2, preadv2)
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/pwrite64.c b/sysdeps/unix/sysv/linux/pwrite64.c
> index 57e5d20..71959c0 100644
> --- a/sysdeps/unix/sysv/linux/pwrite64.c
> +++ b/sysdeps/unix/sysv/linux/pwrite64.c
> @@ -28,6 +28,7 @@ __libc_pwrite64 (int fd, const void *buf, size_t count, off64_t offset)
>  {
>    return SYSCALL_CANCEL (pwrite64, fd, buf, count, SYSCALL_LL64_PRW (offset));
>  }
> +
>  weak_alias (__libc_pwrite64, __pwrite64)
>  libc_hidden_weak (__pwrite64)
>  weak_alias (__libc_pwrite64, pwrite64)
> diff --git a/sysdeps/unix/sysv/linux/pwritev.c b/sysdeps/unix/sysv/linux/pwritev.c
> index ce02996..7545cb3 100644
> --- a/sysdeps/unix/sysv/linux/pwritev.c
> +++ b/sysdeps/unix/sysv/linux/pwritev.c
> @@ -50,4 +50,6 @@ pwritev (int fd, const struct iovec *vector, int count, off_t offset)
>  #  define OFF_T off_t
>  #  include <sysdeps/posix/pwritev_common.c>
>  # endif /* __ASSUME_PREADV  */
> +
> +libc_hidden_def (pwritev)
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/pwritev2.c b/sysdeps/unix/sysv/linux/pwritev2.c
> new file mode 100644
> index 0000000..72f0471
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/pwritev2.c
> @@ -0,0 +1,51 @@
> +/* Linux implementation of pwritev2.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +#include <sysdep-cancel.h>
> +
> +#ifndef __OFF_T_MATCHES_OFF64_T
> +
> +ssize_t
> +pwritev2 (int fd, const struct iovec *vector, int count, off_t offset,
> +	  int flags)
> +{
> +# ifdef __NR_pwritev2
> +  ssize_t result = SYSCALL_CANCEL (pwritev2, fd, vector, count,
> +				   LO_HI_LONG (offset), flags);
> +  if (result >= 0 || errno != ENOSYS)
> +    return result;
> +# endif
> +  /* Trying to emulate the pwritev2 syscall flags is troublesome:
> +
> +     * We can not temporary change the file state of the O_DSYNC and O_SYNC
> +       flags to emulate RWF_{D}SYNC (attempts to change the state of using
> +       fcntl are silently ignored).
> +
> +     * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
> +       semantic not provided by any other flag (O_NONBLOCK for instance).  */
> +
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +  return pwritev (fd, vector, count, offset);
> +}
> +
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/pwritev64.c b/sysdeps/unix/sysv/linux/pwritev64.c
> index 45fb90b..9dc4e55 100644
> --- a/sysdeps/unix/sysv/linux/pwritev64.c
> +++ b/sysdeps/unix/sysv/linux/pwritev64.c
> @@ -48,7 +48,9 @@ pwritev64 (int fd, const struct iovec *vector, int count, off64_t offset)
>  # define OFF_T off64_t
>  # include <sysdeps/posix/pwritev_common.c>
>  #endif
> +libc_hidden_def (pwritev64)
>  
>  #ifdef __OFF_T_MATCHES_OFF64_T
>  strong_alias (pwritev64, pwritev)
> +libc_hidden_def (pwritev)
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/pwritev64v2.c b/sysdeps/unix/sysv/linux/pwritev64v2.c
> new file mode 100644
> index 0000000..def9a0b
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/pwritev64v2.c
> @@ -0,0 +1,55 @@
> +/* Linux implementation of pwritev2 (LFS version).
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/uio.h>
> +#include <sysdep-cancel.h>
> +
> +#if !defined(__NR_pwritev64v2) && defined(__NR_pwritev2)
> +# define __NR_pwritev64v2 __NR_pwritev2
> +#endif
> +
> +ssize_t
> +pwritev64v2 (int fd, const struct iovec *vector, int count, off64_t offset,
> +	     int flags)
> +{
> +#ifdef __NR_pwritev64v2
> +  ssize_t result = SYSCALL_CANCEL (pwritev64v2, fd, vector, count,
> +				   LO_HI_LONG (offset), flags);
> +  if (result >= 0 || errno != ENOSYS)
> +    return result;
> +#endif
> +  /* Trying to emulate the pwritev2 syscall flags is troublesome:
> +
> +     * We can not temporary change the file state of the O_DSYNC and O_SYNC
> +       flags to emulate RWF_{D}SYNC (attempts to change the state of using
> +       fcntl are silently ignored).
> +
> +     * IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
> +       semantic not provided by any other flag (O_NONBLOCK for instance).  */
> +
> +  if (flags != 0)
> +    {
> +      __set_errno (EOPNOTSUPP);
> +      return -1;
> +    }
> +  return pwritev64 (fd, vector, count, offset);
> +}
> +
> +#ifdef __OFF_T_MATCHES_OFF64_T
> +strong_alias (pwritev64v2, pwritev2)
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> index ed1b6bf..eb9e72f 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
> @@ -1980,6 +1980,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> index 2e75d29..1402959 100644
> --- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
> @@ -1881,6 +1881,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/sh/libc.abilist b/sysdeps/unix/sysv/linux/sh/libc.abilist
> index bd74c0c..e9eefcb 100644
> --- a/sysdeps/unix/sysv/linux/sh/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sh/libc.abilist
> @@ -1866,6 +1866,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> index 5584838..967699e 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
> @@ -1972,6 +1972,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> index efedbe2..9dd938a 100644
> --- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
> @@ -1910,6 +1910,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
> index ffd988a..68c9887 100644
> --- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
> @@ -2104,3 +2104,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
> index f0c13ce..97aa0f7 100644
> --- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
> @@ -2104,3 +2104,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> diff --git a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
> index ffd988a..68c9887 100644
> --- a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
> @@ -2104,3 +2104,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> index f57004c..2032659 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> @@ -1861,6 +1861,11 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
>  GLIBC_2.3 GLIBC_2.3 A
>  GLIBC_2.3 __ctype_b_loc F
>  GLIBC_2.3 __ctype_tolower_loc F
> diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> index 05629e1..11a278c 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
> @@ -2104,3 +2104,8 @@ GLIBC_2.25 getrandom F
>  GLIBC_2.25 strfromd F
>  GLIBC_2.25 strfromf F
>  GLIBC_2.25 strfroml F
> +GLIBC_2.26 GLIBC_2.26 A
> +GLIBC_2.26 preadv2 F
> +GLIBC_2.26 preadv64v2 F
> +GLIBC_2.26 pwritev2 F
> +GLIBC_2.26 pwritev64v2 F
> 


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