xfs_io: Add RWF_DONTCACHE support to preadv2

Add per-io RWF_DONTCACHE support flag to preadv2().
This enables xfs_io to perform uncached buffered-io reads.

	e.g. xfs_io -c "pread -U -V 1 0 16K" /mnt/f1

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io/pread.c b/io/pread.c
index b314fbc788cdcc212d751de492e10a4e4919080e..606bfe3656b514f3d094f5a9e8ed87acc2dee81a 100644 (file)
--- 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_PREADV2
+" -U   -- Perform the preadv2() with 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;
@@ -446,6 +454,11 @@ pread_f(
                exitcode = 1;
                return command_usage(&pread_cmd);
        }
+       if (preadv2_flags != 0 && vectors == 0) {
+               printf(_("preadv2 flags require vectored I/O (-V)\n"));
+               exitcode = 1;
+               return command_usage(&pread_cmd);
+       }
 
        offset = cvtnum(fsblocksize, fssectsize, argv[optind]);
        if (offset < 0 && (direction & (IO_RANDOM|IO_BACKWARD))) {
@@ -514,7 +527,7 @@ 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 47af523256999ea16b7ddb2fa1b62f680b04984a..df508054b01cae3365e45bff810651e9bfb34058 100644 (file)
--- 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.