"Darrick J. Wong" <djwong@xxxxxxxxxx> writes:
> On Tue, Mar 04, 2025 at 05:25:37PM +0530, Ritesh Harjani (IBM) wrote:
>> Add per-io RWF_DONTCACHE support flag to preadv2()
>> This enables xfs_io to perform buffered-io read which can drop the page
>> cache folios after reading.
>>
>> e.g. xfs_io -c "pread -U -V 1 0 16K" /mnt/f1
>>
>> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
>> ---
>> io/pread.c | 12 ++++++++++--
>> man/man8/xfs_io.8 | 8 +++++++-
>> 2 files changed, 17 insertions(+), 3 deletions(-)
>>
>> diff --git a/io/pread.c b/io/pread.c
>> index 782f2a36..64c28784 100644
>> --- a/io/pread.c
>> +++ b/io/pread.c
>> @@ -38,6 +38,9 @@ pread_help(void)
>> " -Z N -- zeed the random number generator (used when reading randomly)\n"
>> " (heh, zorry, the -s/-S arguments were already in use in pwrite)\n"
>> " -V N -- use vectored IO with N iovecs of blocksize each (preadv)\n"
>> +#ifdef HAVE_PWRITEV2
>
> HAVE_PREADV2?
>
Thanks for catching that. Will fix this in v2.
-ritesh
> --D
>
>> +" -U -- Perform the preadv2() with Uncached/RWF_DONTCACHE\n"
>> +#endif
>> "\n"
>> " When in \"random\" mode, the number of read operations will equal the\n"
>> " number required to do a complete forward/backward scan of the range.\n"
>> @@ -388,7 +391,7 @@ pread_f(
>> init_cvtnum(&fsblocksize, &fssectsize);
>> bsize = fsblocksize;
>>
>> - while ((c = getopt(argc, argv, "b:BCFRquvV:Z:")) != EOF) {
>> + while ((c = getopt(argc, argv, "b:BCFRquUvV:Z:")) != EOF) {
>> switch (c) {
>> case 'b':
>> tmp = cvtnum(fsblocksize, fssectsize, optarg);
>> @@ -417,6 +420,11 @@ pread_f(
>> case 'u':
>> uflag = 1;
>> break;
>> +#ifdef HAVE_PREADV2
>> + case 'U':
>> + preadv2_flags |= RWF_DONTCACHE;
>> + break;
>> +#endif
>> case 'v':
>> vflag = 1;
>> break;
>> @@ -514,7 +522,7 @@ pread_init(void)
>> pread_cmd.argmin = 2;
>> pread_cmd.argmax = -1;
>> pread_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
>> - pread_cmd.args = _("[-b bs] [-qv] [-i N] [-FBR [-Z N]] off len");
>> + pread_cmd.args = _("[-b bs] [-qUv] [-i N] [-FBR [-Z N]] off len");
>> pread_cmd.oneline = _("reads a number of bytes at a specified offset");
>> pread_cmd.help = pread_help;
>>
>> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
>> index 47af5232..df508054 100644
>> --- a/man/man8/xfs_io.8
>> +++ b/man/man8/xfs_io.8
>> @@ -200,7 +200,7 @@ option will set the file permissions to read-write (0644). This allows xfs_io to
>> set up mismatches between the file permissions and the open file descriptor
>> read/write mode to exercise permission checks inside various syscalls.
>> .TP
>> -.BI "pread [ \-b " bsize " ] [ \-qv ] [ \-FBR [ \-Z " seed " ] ] [ \-V " vectors " ] " "offset length"
>> +.BI "pread [ \-b " bsize " ] [ \-qUv ] [ \-FBR [ \-Z " seed " ] ] [ \-V " vectors " ] " "offset length"
>> Reads a range of bytes in a specified blocksize from the given
>> .IR offset .
>> .RS 1.0i
>> @@ -214,6 +214,12 @@ requests will be split. The default blocksize is 4096 bytes.
>> .B \-q
>> quiet mode, do not write anything to standard output.
>> .TP
>> +.B \-U
>> +Perform the
>> +.BR preadv2 (2)
>> +call with
>> +.IR RWF_DONTCACHE .
>> +.TP
>> .B \-v
>> dump the contents of the buffer after reading,
>> by default only the count of bytes actually read is dumped.
>> --
>> 2.48.1
>>
>>
