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misc: Add support for Linux uio.h RWF_ATOMIC flag

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Linux 6.11 adds the new flag for pwritev2 (commit
c34fc6f26ab86d03a2d47446f42b6cd492dfdc56).

Checked on x86_64-linux-gnu on 6.11 kernel.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Adhemerval Zanella 2024-10-08 15:45:29 -03:00
parent fc650bfd71
commit 5ffc903216
3 changed files with 19 additions and 1 deletions
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13
manual/llio.texi
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@ -1381,6 +1381,19 @@ Per-IO synchronization as if the file was opened with @code{O_APPEND} flag.
@item RWF_NOAPPEND
This flag allows an offset to be honored, even if the file was opened with
@code{O_APPEND} flag.
@item RWF_ATOMIC
Indicate that the write is to be issued with torn-write prevention. The
input buffer should follow some contraints: the total length should be
power-of-2 in size and also sizes between @code{atomic_write_unit_min}
and @code{atomic_write_unit_max}, the @code{struct iovec} count should be
up to @code{atomic_write_segments_max}, and the offset should be
naturally-aligned with regard to total write length.
The @code{atomic_*} values can be obtained with @code{statx} along with
@code{STATX_WRITE_ATOMIC} flag.
This is a Linux-specific extension.
@end vtable
When the source file is compiled with @code{_FILE_OFFSET_BITS == 64} the

5
misc/tst-preadvwritev2-common.c
View File

@ -37,8 +37,11 @@
#ifndef RWF_NOAPPEND
# define RWF_NOAPPEND 0
#endif
#ifndef RWF_ATOMIC
# define RWF_ATOMIC 0
#endif
#define RWF_SUPPORTED (RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT \
| RWF_APPEND | RWF_NOAPPEND)
| RWF_APPEND | RWF_NOAPPEND | RWF_ATOMIC)
/* Generic uio_lim.h does not define IOV_MAX. */
#ifndef IOV_MAX

2
sysdeps/unix/sysv/linux/bits/uio-ext.h
View File

@ -48,6 +48,8 @@ extern ssize_t process_vm_writev (pid_t __pid, const struct iovec *__lvec,
#define RWF_NOWAIT 0x00000008 /* per-IO nonblocking mode. */
#define RWF_APPEND 0x00000010 /* per-IO O_APPEND. */
#define RWF_NOAPPEND 0x00000020 /* per-IO negation of O_APPEND */
#define RWF_ATOMIC 0x00000040 /* Write is to be issued with torn-write
prevention. */
__END_DECLS