[PATCH 5/5 V3] xfs_io: add label command

From: Eric Sandeen <sandeen@sandeen.net>
To: Eric Sandeen <sandeen@redhat.com>, linux-xfs <linux-xfs@vger.kernel.org>
Subject: [PATCH 5/5 V3] xfs_io: add label command
Date: Thu, 17 May 2018 10:22:09 -0500	[thread overview]
Message-ID: <9cee370a-41e2-6dae-4ae1-97fbd7393d38@sandeen.net> (raw)
In-Reply-To: <0f9a7c17-233c-042a-5449-acd7e0a27316@sandeen.net>

This adds an online get/set/clear label command to xfs_io.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

V2: Set exitcode rather than error return on ioctl failure
     fix ioctl definitions o_O

V3: add option parsing to handle -s (set) and -c (clear)

diff --git a/io/Makefile b/io/Makefile
index 88e47517..b40156da 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -10,9 +10,9 @@ LSRCFILES = xfs_bmap.sh xfs_freeze.sh xfs_mkfile.sh
  HFILES = init.h io.h
  CFILES = init.c \
  	attr.c bmap.c cowextsize.c encrypt.c file.c freeze.c fsync.c \
-	getrusage.c imap.c link.c mmap.c open.c parent.c pread.c prealloc.c \
-	pwrite.c reflink.c scrub.c seek.c shutdown.c stat.c swapext.c sync.c \
-	truncate.c utimes.c
+	getrusage.c imap.c label.c link.c mmap.c open.c parent.c pread.c \
+	prealloc.c pwrite.c reflink.c scrub.c seek.c shutdown.c stat.c \
+	swapext.c sync.c truncate.c utimes.c
  
  LLDLIBS = $(LIBXCMD) $(LIBHANDLE) $(LIBFROG) $(LIBPTHREAD)
  LTDEPENDENCIES = $(LIBXCMD) $(LIBHANDLE) $(LIBFROG)
diff --git a/io/init.c b/io/init.c
index 0336c962..612962e8 100644
--- a/io/init.c
+++ b/io/init.c
@@ -72,6 +72,7 @@ init_commands(void)
  	help_init();
  	imap_init();
  	inject_init();
+	label_init();
  	log_writes_init();
  	madvise_init();
  	mincore_init();
diff --git a/io/io.h b/io/io.h
index a2676361..7f8197ca 100644
--- a/io/io.h
+++ b/io/io.h
@@ -109,6 +109,7 @@ extern void		getrusage_init(void);
  extern void		help_init(void);
  extern void		imap_init(void);
  extern void		inject_init(void);
+extern void		label_init(void);
  extern void		mmap_init(void);
  extern void		open_init(void);
  extern void		parent_init(void);
diff --git a/io/label.c b/io/label.c
new file mode 100644
index 00000000..0d163548
--- /dev/null
+++ b/io/label.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2018 Red Hat, Inc.
+ * 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 <sys/ioctl.h>
+#include <sys/mount.h>
+#include "platform_defs.h"
+#include "libxfs.h"
+#include "path.h"
+#include "command.h"
+#include "init.h"
+#include "io.h"
+
+#ifndef FS_IOC_GETFSLABEL
+/* Max chars for the interface; fs limits may differ */
+#define FSLABEL_MAX 256
+#define FS_IOC_GETFSLABEL		_IOR(0x94, 49, char[FSLABEL_MAX])
+#define FS_IOC_SETFSLABEL		_IOW(0x94, 50, char[FSLABEL_MAX])
+#endif
+
+static cmdinfo_t label_cmd;
+
+static void
+label_help(void)
+{
+	printf(_(
+"\n"
+" Manipulate or query the filesystem label while mounted.\n"
+"\n"
+" With no arguments, displays the current filesystem label.\n"
+" -s newlabel -- set the filesystem label to newlabel\n"
+" -c          -- clear the filesystem label (sets to NULL string)\n"
+"\n"));
+}
+
+static int
+label_f(
+	int		argc,
+	char		**argv)
+{
+	int		c;
+	int		error;
+	char		label[FSLABEL_MAX];
+
+	if (argc == 1) {
+		memset(label, 0, sizeof(label));
+		error = ioctl(file->fd, FS_IOC_GETFSLABEL, &label);
+		goto out;
+	}
+
+	while ((c = getopt(argc, argv, "cs:")) != EOF) {
+		switch (c) {
+		case 'c':
+			label[0] = '\0';
+			break;
+		case 's':
+			strncpy(label, optarg, sizeof(label));
+			break;
+		default:
+			return command_usage(&label_cmd);
+		}
+	}
+
+	/* Check for trailing arguments */
+	if (argc != optind)
+		return command_usage(&label_cmd);
+
+	error = ioctl(file->fd, FS_IOC_SETFSLABEL, label);
+out:
+	if (error) {
+		perror("label");
+		exitcode = 1;
+	} else {
+		printf("label = \"%s\"\n", label);
+	}
+
+	return 0;
+}
+
+void
+label_init(void)
+{
+	label_cmd.name = "label";
+	label_cmd.cfunc = label_f;
+	label_cmd.argmin = 0;
+	label_cmd.argmax = 3;
+	label_cmd.args = _("[-s label|-c]");
+	label_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
+	label_cmd.oneline =
+		_("query, set, or clear the filesystem label while mounted");
+	label_cmd.help = label_help;
+
+	add_command(&label_cmd);
+}
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index c3ab532d..82ea8c1a 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -1175,6 +1175,19 @@ This is intended to be equivalent to the shell command:
  See the
  .B log_writes
  command.
+.TP
+.BI "label" " " "[ -c | -s " label " ] "
+On filesystems that support online label manipulation, get, set, or clear the
+filesystem label.  With no options, print the current filesystem label.  The
+.B \-c
+option clears the filesystem label by setting it to the null string.  The
+.BI "\-s " label
+option sets the filesystem label to
+.IR label .
+If the label is longer than the filesystem will accept,
+.B xfs_io
+will print an error message.  XFS filesystem labels can be at most 12
+characters long.
  .SH SEE ALSO
  .BR mkfs.xfs (8),
  .BR xfsctl (3),

