xfs: add xfs_mount sysfs kobject

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>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

6 files changed, 133 insertions, 1 deletions

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 0dfa26d626f5..d61799949580 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -86,6 +86,7 @@ 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_linux.h b/fs/xfs/xfs_linux.h
index f59b966bf903..8312771c2b5b 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -191,6 +191,17 @@ typedef __uint64_t __psunsigned_t;
 #define MAX(a,b)        (max(a,b))
 #define howmany(x, y)   (((x)+((y)-1))/(y))
 
+/*
+ * XFS wrapper structure for sysfs support. It depends on external data
+ * structures and is embedded in various internal data structures to implement
+ * the XFS sysfs object heirarchy. Define it here for broad access throughout
+ * the codebase.
+ */
+struct xfs_kobj {
+        struct kobject          kobject;
+        struct completion       complete;
+};
+
 /* Kernel uid/gid conversion. These are used to convert to/from the on disk
  * uid_t/gid_t types to the kuid_t/kgid_t types that the kernel uses internally.
  * The conversion here is type only, the value will remain the same since we
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 4e9dd4a9c69a..c8a328ee2c2a 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 +734,15 @@ xfs_mountfs(
 
         xfs_set_maxicount(mp);
 
-        error = xfs_uuid_mount(mp);
+        mp->m_kobj.kobject.kset = xfs_kset;
+        error = xfs_sysfs_init(&mp->m_kobj, &xfs_mp_ktype, 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 +997,8 @@ xfs_mountfs(
         xfs_da_unmount(mp);
  out_remove_uuid:
         xfs_uuid_unmount(mp);
+ out_remove_sysfs:
+        xfs_sysfs_del(&mp->m_kobj);
  out:
         return error;
 }
@@ -1071,6 +1081,8 @@ xfs_unmountfs(
         xfs_errortag_clearall(mp, 0);
 #endif
         xfs_free_perag(mp);
+
+        xfs_sysfs_del(&mp->m_kobj);
 }
 
 int
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 7295a0b7c343..b0447c86e7e2 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -166,6 +166,7 @@ typedef struct xfs_mount {
                                                    on the next remount,rw */
         int64_t                 m_low_space[XFS_LOWSP_MAX];
                                                 /* low free space thresholds */
+        struct xfs_kobj         m_kobj;
 
         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 000000000000..ae9aa7a1a06a
--- /dev/null
+++ b/fs/xfs/xfs_sysfs.c
@@ -0,0 +1,49 @@
+/*
+ * 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 "xfs.h"
+#include "xfs_sysfs.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);
+};
+
+static inline struct xfs_sysfs_attr *
+to_attr(struct attribute *attr)
+{
+        return container_of(attr, struct xfs_sysfs_attr, attr);
+}
+
+#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.
+ */
+
+struct kobj_type xfs_mp_ktype = {
+        .release = xfs_sysfs_release,
+};
diff --git a/fs/xfs/xfs_sysfs.h b/fs/xfs/xfs_sysfs.h
new file mode 100644
index 000000000000..4bd5fff75d0f
--- /dev/null
+++ b/fs/xfs/xfs_sysfs.h
@@ -0,0 +1,58 @@
+/*
+ * 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 struct xfs_kobj *
+to_kobj(struct kobject *kobject)
+{
+        return container_of(kobject, struct xfs_kobj, kobject);
+}
+
+static inline void
+xfs_sysfs_release(struct kobject *kobject)
+{
+        struct xfs_kobj *kobj = to_kobj(kobject);
+        complete(&kobj->complete);
+}
+
+static inline int
+xfs_sysfs_init(
+        struct xfs_kobj         *kobj,
+        struct kobj_type        *ktype,
+        struct xfs_kobj         *parent_kobj,
+        const char              *name)
+{
+        init_completion(&kobj->complete);
+        return kobject_init_and_add(&kobj->kobject, ktype,
+                                    &parent_kobj->kobject, "%s", name);
+}
+
+static inline void
+xfs_sysfs_del(
+        struct xfs_kobj *kobj)
+{
+        kobject_del(&kobj->kobject);
+        kobject_put(&kobj->kobject);
+        wait_for_completion(&kobj->complete);
+}
+
+#endif  /* __XFS_SYSFS_H__ */