[PATCH v2] xfs_io: add the lseek() SEEK_DATA/SEEK_HOLE support

Mark Tinguely
2012-10-23T20:01:24Z

[-- Attachment #1: v2-xfs_io-support-SEEK_DATA-SEEK_HOLE.patch --]
[-- Type: text/plain, Size: 8532 bytes --]

Add the lseek SEEK_DATA/SEEK_HOLE support into xfs_io.
The result from the lseek() call will be printed to the output.
For example:

xfs_io> lseek -h 609k
Type Offset
hole 630784

Signed-off-by: Mark Tinguely <tinguely@sgi.com>
---
configure.in | 1
include/builddefs.in | 1
io/Makefile | 5 +
io/init.c | 1
io/io.h | 6 +
io/lseek.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++++++
m4/package_libcdev.m4 | 15 ++++
man/man8/xfs_io.8 | 35 ++++++++++
8 files changed, 229 insertions(+)

Index: b/configure.in
===================================================================
--- a/configure.in
+++ b/configure.in
@@ -109,6 +109,7 @@ AC_HAVE_GETMNTINFO
AC_HAVE_FALLOCATE
AC_HAVE_FIEMAP
AC_HAVE_PREADV
+AC_HAVE_LSEEK_DATA
AC_HAVE_SYNC_FILE_RANGE
AC_HAVE_BLKID_TOPO($enable_blkid)

Index: b/include/builddefs.in
===================================================================
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -102,6 +102,7 @@ HAVE_GETMNTINFO = @have_getmntinfo@
HAVE_FALLOCATE = @have_fallocate@
HAVE_FIEMAP = @have_fiemap@
HAVE_PREADV = @have_preadv@
+HAVE_LSEEK_DATA = @have_lseek_data@
HAVE_SYNC_FILE_RANGE = @have_sync_file_range@

GCCFLAGS = -funsigned-char -fno-strict-aliasing -Wall
Index: b/io/Makefile
===================================================================
--- a/io/Makefile
+++ b/io/Makefile
@@ -80,6 +80,11 @@ ifeq ($(HAVE_PREADV),yes)
LCFLAGS += -DHAVE_PREADV -DHAVE_PWRITEV
endif

+ifeq ($(HAVE_LSEEK_DATA),yes)
+LCFLAGS += -DHAVE_LSEEK_DATA
+CFILES += lseek.c
+endif
+
default: depend $(LTCOMMAND)

include $(BUILDRULES)
Index: b/io/init.c
===================================================================
--- a/io/init.c
+++ b/io/init.c
@@ -64,6 +64,7 @@ init_commands(void)
help_init();
imap_init();
inject_init();
+ lseek_init();
madvise_init();
mincore_init();
mmap_init();
Index: b/io/io.h
===================================================================
--- a/io/io.h
+++ b/io/io.h
@@ -108,6 +108,12 @@ extern void quit_init(void);
extern void shutdown_init(void);
extern void truncate_init(void);

+#ifdef HAVE_LSEEK_DATA
+extern void lseek_init(void);
+#else
+#define lseek_init() do { } while (0)
+#endif
+
#ifdef HAVE_FADVISE
extern void fadvise_init(void);
#else
Index: b/io/lseek.c
===================================================================
--- /dev/null
+++ b/io/lseek.c
@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2012 SGI
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/fs.h>
+
+#include <sys/uio.h>
+#include <xfs/xfs.h>
+#include <xfs/command.h>
+#include <xfs/input.h>
+#include <ctype.h>
+#include "init.h"
+#include "io.h"
+
+static cmdinfo_t lseek_cmd;
+
+static void
+lseek_help(void)
+{
+ printf(_(
+"\n"
+" returns the next hole and/or data offset at or after the specified offset\n"
+"\n"
+" Example:\n"
+" 'lseek -d 512' - offset of data at or following offset 512\n"
+" 'lseek -a -r 0' - offsets of all data and hole in entire file\n"
+"\n"
+" Returns the offset of the next data and/or hole. There is an implied hole\n"
+" at the end of file. If the specified offset is past end of file, or there\n"
+" is no data past the specied offset, EOF is returned.\n"
+" -a -- return the next data and hole starting at the specified offset.\n"
+" -d -- return the next data starting at the specified offset.\n"
+" -h -- return the next hole starting at the specified offset.\n"
+" -r -- return all remaining type(s) starting at the specified offset.\n"
+"\n"));
+}
+
+#define LSEEK_DFLAG 1 << 0
+#define LSEEK_HFLAG 1 << 1
+#define LSEEK_RFLAG 1 << 2
+
+static int
+lseek_f(
+ int argc,
+ char **argv)
+{
+ off64_t offset, off, roff;
+ size_t fsblocksize, fssectsize;
+ int cseg;
+ int flag;
+ int i, c;
+
+ flag = 0;
+ init_cvtnum(&fsblocksize, &fssectsize);
+
+ while ((c = getopt(argc, argv, "adhr")) != EOF) {
+ switch (c) {
+ case 'a':
+ flag |= LSEEK_HFLAG;
+ /* fall through to pick up the DFLAG */
+ case 'd':
+ flag |= LSEEK_DFLAG;
+ break;
+ case 'h':
+ flag |= LSEEK_HFLAG;
+ break;
+ case 'r':
+ flag |= LSEEK_RFLAG;
+ break;
+ default:
+ return command_usage(&lseek_cmd);
+ }
+ }
+ /* must have hole or data specified and an offset */
+ if (!(flag & (LSEEK_DFLAG | LSEEK_HFLAG)) ||
+ optind != argc - 1)
+ return command_usage(&lseek_cmd);
+
+ offset = cvtnum(fsblocksize, fssectsize, argv[optind]);
+
+ /* recursively display all information, decide where to start. */
+ off = lseek64(file->fd, offset, SEEK_DATA);
+ if (off == offset)
+ cseg = LSEEK_DFLAG;
+ else
+ cseg = LSEEK_HFLAG;
+
+ printf("Type offset\n");
+
+ /* loop to handle the data / hole entries in assending order.
+ * Only display the EOF when the initial offset was greater
+ * the end of file.
+ */
+ for (i = 0; flag & LSEEK_RFLAG || i < 2; i++) {
+ if (cseg == LSEEK_DFLAG) {
+ if (flag & LSEEK_DFLAG) {
+ roff = lseek64(file->fd, offset, SEEK_DATA);
+ if (roff == -1) {
+ if (i < 2) {
+ if (errno == ENXIO)
+ printf("data EOF\n");
+ else
+ printf("data %d\n",
+ -errno);
+ }
+ break;
+ } else
+ printf("data %lld\n", roff);
+ }
+ /* set the offset and type for the next iteration */
+ cseg = LSEEK_HFLAG;
+ offset = lseek64(file->fd, offset, SEEK_HOLE);
+ continue;
+ }
+
+ /* cseg == LSEEK_HFLAG */
+ if (flag & LSEEK_HFLAG) {
+ roff = lseek64(file->fd, offset, SEEK_HOLE);
+ if (roff == -1) {
+ if (i < 2) {
+ if (errno == ENXIO)
+ printf("hole EOF\n");
+ else
+ printf("hole %d\n", -errno);
+ }
+ break;
+ } else
+ printf("hole %lld\n", roff);
+ }
+ /* set the offset and type for the next iteration */
+ cseg = LSEEK_DFLAG;
+ offset = lseek64(file->fd, offset, SEEK_DATA);
+ }
+ return 0;
+}
+
+void
+lseek_init(void)
+{
+ lseek_cmd.name = "lseek";
+ lseek_cmd.altname = "seek";
+ lseek_cmd.cfunc = lseek_f;
+ lseek_cmd.argmin = 2;
+ lseek_cmd.argmax = 5;
+ lseek_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
+ lseek_cmd.args = _("-a | -d | -h [-r] off");
+ lseek_cmd.oneline = _("locate the next data and/or hole");
+ lseek_cmd.help = lseek_help;
+
+ add_command(&lseek_cmd);
+}
Index: b/m4/package_libcdev.m4
===================================================================
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -153,6 +153,21 @@ AC_DEFUN([AC_HAVE_PREADV],
AC_SUBST(have_preadv)
])

+#
+# Check if we have a working fadvise system call
+#
+AC_DEFUN([AC_HAVE_LSEEK_DATA],
+ [ AC_MSG_CHECKING([for lseek SEEK_DATA])
+ AC_TRY_COMPILE([
+#include <linux/fs.h>
+ ], [
+ lseek(0, 0, SEEK_DATA);
+ ], have_lseek_data=yes
+ AC_MSG_RESULT(yes),
+ AC_MSG_RESULT(no))
+ AC_SUBST(have_lseek_data)
+ ])
+
#
# Check if we have a sync_file_range libc call (Linux)
#
Index: b/man/man8/xfs_io.8
===================================================================
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -377,6 +377,41 @@ must be specified as another open file
.RB ( \-f )
or by path
.RB ( \-i ).
+.TP
+.BI "lseek \-a | \-d | \-h [ \-r ] offset"
+On platforms that support the
+.BR lseek (2)
+.B SEEK_DATA
+and
+.B SEEK_HOLE
+options, display the offsets of the specified segments.
+.RS 1.0i
+.PD 0
+.TP 0.4i
+.B \-a
+Display both
+.B data
+and
+.B hole
+segments starting at the specified
+.B offset.
+.TP
+.B \-d
+Display the
+.B data
+segment starting at the specified
+.B offset.
+.TP
+.B \-h
+Display the
+.B hole
+segment starting at the specified
+.B offset.
+.TP
+.B \-r
+Recursively display all the specified segments starting at the specified
+.B offset.
+.TP

.SH MEMORY MAPPED I/O COMMANDS
.TP