On 10/09/2017 12:19 PM, Darrick J. Wong wrote:
> On Fri, Sep 29, 2017 at 08:00:34AM -0500, Goldwyn Rodrigues wrote:
>> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>>
>> This allows to make pwritev2() calls with RWF_NOWAIT,
>> which would fail in case the call blocks.
>>
>> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>> ---
>> io/pwrite.c | 8 +++++++-
>> man/man8/xfs_io.8 | 6 ++++++
>> 2 files changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/io/pwrite.c b/io/pwrite.c
>> index e7d411bb..2b85a528 100644
>> --- a/io/pwrite.c
>> +++ b/io/pwrite.c
>> @@ -52,6 +52,9 @@ pwrite_help(void)
>> " (heh, zorry, the -s/-S arguments were already in use in pwrite)\n"
>> #ifdef HAVE_PWRITEV
>> " -V N -- use vectored IO with N iovecs of blocksize each (pwritev)\n"
>> +#ifdef HAVE_PWRITEV2
>> +" -N -- Perform the pwritev2() with RWF_NOWAIT\n"
>> +#endif
>
> Separate these two? i.e.
>
> #ifdef HAVE_PWRITEV
> " -V N..."
> #endif
> #ifdef HAVE_PWRITEV2
> " -N ..."
> #endif
>
> They're tested separately in configure, so the ifdefs needn't be nested.
>
>> #endif
>> "\n"));
>> }
>> @@ -276,7 +279,7 @@ pwrite_f(
>> init_cvtnum(&fsblocksize, &fssectsize);
>> bsize = fsblocksize;
>>
>> - while ((c = getopt(argc, argv, "b:BCdf:Fi:qRs:S:uV:wWZ:")) != EOF) {
>> + while ((c = getopt(argc, argv, "b:BCdf:Fi:NqRs:S:uV:wWZ:")) != EOF) {
>> switch (c) {
>> case 'b':
>> tmp = cvtnum(fsblocksize, fssectsize, optarg);
>> @@ -305,6 +308,9 @@ pwrite_f(
>> case 'i':
>> infile = optarg;
>> break;
>> + case 'N':
>> + pwritev2_flags |= RWF_NOWAIT;
>> + break;
>
> Needs #ifdef HAVE_PWRITEV2.
>
> If you feel the need to be extra cautious, you could also put:
>
> #ifndef HAVE_PWRITEV2
> assert(pwritev2_flags == 0);
> #endif
>
> ...just after the getopt parsing to make sure that we never silently
> drop RWF_* flags due to code bugs.
>
Instead I am planning to put an #else to #ifdef in the case 'N' to make
sure that people who do not have pwritev2() get the proper message
instead of the command failing without reason.
+ case 'N':
+#ifdef HAVE_PWRITEV2
+ pwritev2_flags |= RWF_NOWAIT;
+ break;
+#else
+ printf(_("-N: Kernel does not support
pwritev2()\n"));
+ return 0;
+#endif
> --D
>
>> case 's':
>> skip = cvtnum(fsblocksize, fssectsize, optarg);
>> if (skip < 0) {
>> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
>> index 0fd9b951..9c58914f 100644
>> --- a/man/man8/xfs_io.8
>> +++ b/man/man8/xfs_io.8
>> @@ -282,6 +282,12 @@ Use the vectored IO write syscall
>> with a number of blocksize length iovecs. The number of iovecs is set by the
>> .I vectors
>> parameter.
>> +.TP
>> +.B \-N
>> +Perform the
>> +.BR pwritev2 (2)
>> +call with
>> +.I RWF_NOWAIT.
>> .RE
>> .PD
>> .TP
>> --
>> 2.14.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Goldwyn
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
