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?
--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
>
>
