[PATCH 3/6] xfs: add xfs_mount sysfs kobject

[Brian Foster <bfoster@redhat.com>]

Embed a base kobject into xfs_mount. This creates a kobject associated
with each XFS mount and a subdirectory in sysfs with the name of the
filesystem. The subdirectory lifecycle matches that of the mount. Also
add the new xfs_sysfs.[c,h] source files with some XFS sysfs
infrastructure to facilitate attribute creation.

Note that there are currently no attributes exported as part of the
xfs_mount kobject. It exists solely to serve as a per-mount container
for child objects.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/Makefile    |  1 +
 fs/xfs/xfs_mount.c | 15 ++++++++++++++-
 fs/xfs/xfs_mount.h |  2 ++
 fs/xfs/xfs_sysfs.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_sysfs.h | 46 ++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 119 insertions(+), 1 deletion(-)
 create mode 100644 fs/xfs/xfs_sysfs.c
 create mode 100644 fs/xfs/xfs_sysfs.h

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index c21f435..d8da236 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -51,6 +51,7 @@ xfs-y				+= xfs_aops.o \
 				   xfs_mru_cache.o \
 				   xfs_super.o \
 				   xfs_symlink.o \
+				   xfs_sysfs.o \
 				   xfs_trans.o \
 				   xfs_xattr.o \
 				   kmem.o \
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 8a41aba..656614b 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -42,6 +42,7 @@
 #include "xfs_trace.h"
 #include "xfs_icache.h"
 #include "xfs_dinode.h"
+#include "xfs_sysfs.h"
 
 
 #ifdef HAVE_PERCPU_SB
@@ -60,6 +61,8 @@ static DEFINE_MUTEX(xfs_uuid_table_mutex);
 static int xfs_uuid_table_size;
 static uuid_t *xfs_uuid_table;
 
+extern struct kset *xfs_kset;
+
 /*
  * See if the UUID is unique among mounted XFS filesystems.
  * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
@@ -731,10 +734,16 @@ xfs_mountfs(
 
 	xfs_set_maxicount(mp);
 
-	error = xfs_uuid_mount(mp);
+	mp->m_kobject.kset = xfs_kset;
+	error = xfs_sysfs_init(&mp->m_kobject, &xfs_mp_ktype,
+			&mp->m_kobject_complete, NULL, mp->m_fsname);
 	if (error)
 		goto out;
 
+	error = xfs_uuid_mount(mp);
+	if (error)
+		goto out_remove_sysfs;
+
 	/*
 	 * Set the minimum read and write sizes
 	 */
@@ -989,6 +998,8 @@ xfs_mountfs(
 	xfs_da_unmount(mp);
  out_remove_uuid:
 	xfs_uuid_unmount(mp);
+ out_remove_sysfs:
+	xfs_sysfs_del(&mp->m_kobject, &mp->m_kobject_complete);
  out:
 	return error;
 }
@@ -1071,6 +1082,8 @@ xfs_unmountfs(
 	xfs_errortag_clearall(mp, 0);
 #endif
 	xfs_free_perag(mp);
+
+	xfs_sysfs_del(&mp->m_kobject, &mp->m_kobject_complete);
 }
 
 int
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 7295a0b..6d7e5d7 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -166,6 +166,8 @@ typedef struct xfs_mount {
 						   on the next remount,rw */
 	int64_t			m_low_space[XFS_LOWSP_MAX];
 						/* low free space thresholds */
+	struct kobject		m_kobject;
+	struct completion	m_kobject_complete;
 
 	struct workqueue_struct	*m_data_workqueue;
 	struct workqueue_struct	*m_unwritten_workqueue;
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
new file mode 100644
index 0000000..41365fe
--- /dev/null
+++ b/fs/xfs/xfs_sysfs.c
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2014 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 <linux/sysfs.h>
+#include "xfs.h"
+#include "xfs_types.h"
+#include "xfs_sb.h"
+#include "xfs_trans_resv.h"
+#include "xfs_ag.h"
+#include "xfs_mount.h"
+
+struct xfs_sysfs_attr {
+	struct attribute attr;
+	ssize_t (*show)(char *buf, void *data);
+	ssize_t (*store)(const char *buf, size_t count, void *data);
+};
+
+#define XFS_SYSFS_ATTR_RW(name) \
+	static struct xfs_sysfs_attr xfs_sysfs_attr_##name = __ATTR_RW(name)
+#define XFS_SYSFS_ATTR_RO(name) \
+	static struct xfs_sysfs_attr xfs_sysfs_attr_##name = __ATTR_RO(name)
+
+#define ATTR_LIST(name) &xfs_sysfs_attr_##name.attr
+
+/*
+ * xfs_mount kobject. This currently has no attributes and thus no need for show
+ * and store helpers. The mp kobject serves as the per-mount parent object that
+ * is identified by the fsname under sysfs.
+ */
+
+STATIC void
+xfs_mp_release(struct kobject *kobj)
+{
+	struct xfs_mount *mp = container_of(kobj, struct xfs_mount, m_kobject);
+
+	complete(&mp->m_kobject_complete);
+}
+
+struct kobj_type xfs_mp_ktype = {
+	.release = xfs_mp_release,
+};
diff --git a/fs/xfs/xfs_sysfs.h b/fs/xfs/xfs_sysfs.h
new file mode 100644
index 0000000..c885acf
--- /dev/null
+++ b/fs/xfs/xfs_sysfs.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2014 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
+ */
+
+#ifndef __XFS_SYSFS_H__
+#define __XFS_SYSFS_H__
+
+extern struct kobj_type xfs_mp_ktype;	/* xfs_mount */
+
+static inline int
+xfs_sysfs_init(
+	struct kobject		*kobj,
+	struct kobj_type	*ktype,
+	struct completion	*complete,
+	struct kobject		*parent,
+	const char		*name)
+{
+	init_completion(complete);
+	return kobject_init_and_add(kobj, ktype, parent, "%s", name);
+}
+
+static inline void
+xfs_sysfs_del(
+	struct kobject		*kobj,
+	struct completion	*complete)
+{
+	kobject_del(kobj);
+	kobject_put(kobj);
+	wait_for_completion(complete);
+}
+
+#endif	/* __XFS_SYSFS_H__ */
-- 
1.8.3.1

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