This patch started as an xfstest to test Jeff's advanced seek_data
features. The C code we had for that feature was deemed as an xfs_io
feature.
On 08/20/13 18:07, Eric Sandeen wrote:
On 8/16/13 3:54 PM, Mark Tinguely wrote:
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
HOLE not hole, I guess. ;)
I was going to say that's a lot of verbosity for a single output,
but I guess the other options might have many lines, so I suppose
it makes sense.
(I was just thinking about what xfstests might need to do to filter
& parse output...)
parsing is a bear because there are multiple correct answers.
There is always a legal hole at EOF and that if SEEK_HOLE is not
implemented that is the answer they give.
Different versions of XFS seek_data code will give different answer to
the same test depending on what is supported in that version.
Signed-off-by: Mark Tinguely<tinguely@xxxxxxx>
---
Not trying to be difficult. Dave wanted the single hole/data/hole and data
seperated from the recursive loop, but doing it that way is basically unrolling
the loop into a if-then-else and is really terrible. If this is still not
acceptable, then we can throw this feature into /dev/null.
configure.ac | 1
include/builddefs.in | 1
io/Makefile | 5 +
io/init.c | 1
io/io.h | 6 +
io/seek.c | 187 ++++++++++++++++++++++++++++++++++++++++++++++++++
m4/package_libcdev.m4 | 15 ++++
man/man8/xfs_io.8 | 35 +++++++++
8 files changed, 251 insertions(+)
Index: b/configure.ac
===================================================================
--- a/configure.ac
+++ b/configure.ac
@@ -110,6 +110,7 @@ AC_HAVE_GETMNTINFO
AC_HAVE_FALLOCATE
AC_HAVE_FIEMAP
AC_HAVE_PREADV
+AC_HAVE_SEEK_DATA
AC_HAVE_SYNC_FILE_RANGE
AC_HAVE_BLKID_TOPO($enable_blkid)
AC_HAVE_READDIR
Index: b/include/builddefs.in
===================================================================
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -102,6 +102,7 @@ HAVE_GETMNTINFO = @have_getmntinfo@
HAVE_FALLOCATE = @have_fallocate@
HAVE_FIEMAP = @have_fiemap@
HAVE_PREADV = @have_preadv@
+HAVE_SEEK_DATA = @have_seek_data@
HAVE_SYNC_FILE_RANGE = @have_sync_file_range@
HAVE_READDIR = @have_readdir@
Index: b/io/Makefile
===================================================================
--- a/io/Makefile
+++ b/io/Makefile
@@ -85,6 +85,11 @@ CFILES += readdir.c
LCFLAGS += -DHAVE_READDIR
endif
+ifeq ($(HAVE_SEEK_DATA),yes)
+LCFLAGS += -DHAVE_SEEK_DATA
+CFILES += seek.c
see below; we should unconditionally compile, but conditionally
locally define SEEK_DATA / SEEK_HOLE
It was put in to check if SEEK_DATA is supported.
Yes, it expects the user headers to reflect what the kernel is capable
of doing.
If you don't want it, then it will be removed.
+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();
+ seek_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_SEEK_DATA
+extern void seek_init(void);
+#else
+#define seek_init() do { } while (0)
+#endif
this can go when we unconditionally compile it in
+
#ifdef HAVE_FADVISE
extern void fadvise_init(void);
#else
Index: b/io/seek.c
===================================================================
--- /dev/null
+++ b/io/seek.c
@@ -0,0 +1,187 @@
+/*
+ * Copyright (c) 2013 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<libxfs.h>
hm, including this clashes w/ the min() define in io/init.h,
which is maybe a separate problem down the line, but libxfs.h
isn't required anyway for this file, so I'd just drop this include.
+#include<linux/fs.h>
I think the previous review had a problem with this header which should
be removed.
+
+#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"
#ifndef HAVE_SEEK_DATA
#define SEEK_DATA 3 /* seek to the next data */
#define SEEK_HOLE 4 /* seek to the next hole */
#endif
+
+static cmdinfo_t seek_cmd;
+
+static void
+seek_help(void)
+{
+ printf(_(
+"\n"
+" returns the next hole and/or data offset at or after the specified offset\n"
+"\n"
+" Example:\n"
+" 'seek -d 512' - offset of data at or following offset 512\n"
+" 'seek -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.
is this expected, given the hole at the end of the file? This is for a single
non-sparse file:
xfs_io> seek -ar 0
Type offset
DATA 0
HOLE 3022
DATA EOF
That last line doesn't make sense, does it?
Parsing is the reason the entry is there so the output always has
consistent ending entry - some queries that is the only answer (or now
no message) no biggy one way or the other.
If the specified offset is past end of file, or there\n"
+" is no data past the specied offset, EOF is returned.\n"
"specified"
+" -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 SEEK_DFLAG (1<< 0)
+#define SEEK_HFLAG (1<< 1)
+#define SEEK_RFLAG (1<< 2)
+#define DATA 0
+#define HOLE 1
+
+struct seekinfo {
+ char *name;
+ int seektype;
+ int mask;
+} seekinfo[] = {
+ {"DATA", SEEK_DATA, SEEK_DFLAG},
+ {"HOLE", SEEK_HOLE, SEEK_HFLAG}
I guess "DATA" doesn't get replaced by "0" ? Sorry, I failed cpp 101.
It prints the right thing so I guess not. ;)
:) no the defines are subscripts = see "current ="
+};
+
+void
+seek_output(
+ char *type,
+ off64_t offset)
+{
+ if (offset == -1) {
+ if (errno == ENXIO)
+ printf("%s EOF\n", type);
+ else
+ printf("%s ERR %d\n", type, errno);
+ } else
+ printf("%s %ld\n", type, offset);
+}
+
+static int
+seek_f(
+ int argc,
+ char **argv)
+{
+ off64_t offset, result;
+ size_t fsblocksize, fssectsize;
+ int flag;
+ int current; /* specify data or hole */
+ int c;
+
+ flag = 0;
+ init_cvtnum(&fsblocksize,&fssectsize);
+
+ while ((c = getopt(argc, argv, "adhr")) != EOF) {
+ switch (c) {
+ case 'a':
+ flag |= (SEEK_HFLAG | SEEK_DFLAG);
+ break;
+ case 'd':
+ flag |= SEEK_DFLAG;
+ break;
+ case 'h':
+ flag |= SEEK_HFLAG;
+ break;
+ case 'r':
+ flag |= SEEK_RFLAG;
+ break;
+ default:
+ return command_usage(&seek_cmd);
+ }
+ }
+ /* must have hole or data specified and an offset */
+ if (!(flag& (SEEK_DFLAG | SEEK_HFLAG)) ||
+ optind != argc - 1)
+ return command_usage(&seek_cmd);
+
+ offset = cvtnum(fsblocksize, fssectsize, argv[optind]);
need to error check that:
xfs_io> seek -a 8x8
Type offset
HOLE EOF
Some version of XFS seek_data will treat it as a 0, but okay.
+
+ if (flag& SEEK_HFLAG) {
+ result = lseek64(file->fd, offset, SEEK_HOLE);
+ if ((result == offset) ||
+ !(flag& SEEK_DFLAG)) {
+ offset = result; /* in case it was EOF */
+ current = HOLE;
+ goto found_hole;
+ }
what if result< 0?
see below - no hole or error
# io/xfs_io /tmp/fifo
xfs_io> seek -a 0
Type offset
DATA ERR 29
hum I guess seek_output handles it? perror would be nice, maybe?
+ }
+
+ /* found data or -1 when "-a" option was requested */
+ current = DATA;
+ offset = lseek64(file->fd, offset, SEEK_DATA);
Ok, I guess I have to think harder about how the error handling
from lseek is supposed to work.
not a hole
+
+found_hole:
At this point we figure out what come first, a hole or data.
we have to alternate between request to find the next hole and/or data
we print the item(s) that we want along the way.
if we do not find what we are looking for or get an error it is time to
stop.
+ printf("Type offset\n");
+
+ while (flag) {
+ /*
+ * handle the data / hole entries in assending order from
+ * the specified offset.
+ *
+ * flag determines if there are more items to be displayed.
+ * SEEK_RFLAG is an infinite loop that is terminated with
+ * a offset at EOF.
+ *
+ * current determines next type to process/display where
+ * 0 is data and 1 is data.
+ */
+
+ if (flag& seekinfo[current].mask) {
+ seek_output(seekinfo[current].name, offset);
+ if (offset == -1)
+ break; /* stop on error or EOF */
+ }
+
+ /*
+ * When displaying only a single data and/or hole item, mask
+ * off the item as it is displayed. The loop will end when all
+ * requested items have been displayed.
+ */
+ if (!(flag& SEEK_RFLAG))
+ flag&= ~seekinfo[current].mask;
+
+ current ^= 1; /* alternate between data and hole */
+ if (offset != -1)
+ offset = lseek64(file->fd, offset,
+ seekinfo[current].seektype);
+ }
+ return 0;
+}
+
+void
+seek_init(void)
+{
+ seek_cmd.name = "seek";
+ seek_cmd.altname = "seek";
altname isn't required, but I don't think there's a reason to re-specify the same name.
+ seek_cmd.cfunc = seek_f;
+ seek_cmd.argmin = 2;
+ seek_cmd.argmax = 5;
+ seek_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
+ seek_cmd.args = _("-a | -d | -h [-r] off");
+ seek_cmd.oneline = _("locate the next data and/or hole");
+ seek_cmd.help = seek_help;
+
+ add_command(&seek_cmd);
+}
Index: b/m4/package_libcdev.m4
===================================================================
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -154,6 +154,21 @@ AC_DEFUN([AC_HAVE_PREADV],
])
#
+# Check if we have a working fadvise system call
fadvise...? ;)
my bad, a cut/paste bug.
+#
+AC_DEFUN([AC_HAVE_SEEK_DATA],
+ [ AC_MSG_CHECKING([for seek_data ])
So really, we're checking for the SEEK_DATA& SEEK_HOLE defines here.
If they aren't present, we can locally define them, and we'll still get
the functionality (though io has to cope w/ EINVAL or whatnot if the
system xfs_io runs on doesn't understand the flags)
Also, coverity didn't find any errors in seek.c \o/ :)
If that is what is desired.
Thanks,
-Eric
+ AC_TRY_COMPILE([
+#include<linux/fs.h>
+ ], [
+ lseek(0, 0, SEEK_DATA);
+ ], have_seek_data=yes
+ AC_MSG_RESULT(yes),
+ AC_MSG_RESULT(no))
+ AC_SUBST(have_seek_data)
+ ])
+
+#
# Check if we have a sync_file_range libc call (Linux)
#
AC_DEFUN([AC_HAVE_SYNC_FILE_RANGE],
Index: b/man/man8/xfs_io.8
===================================================================
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -418,6 +418,41 @@ to read (in bytes)
.RE
.PD
.TP
+.TP
+.BI "seek \-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
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