[PATCH] dm/md dependency tree in sysfs: holders/slaves subdirectory

Creating "slaves" and "holders" directories in /sys/block/<disk> and
creating "holders" directory under /sys/block/<disk>/<partition>

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 43 insertions, 0 deletions

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index f924f459bdb..60523cea713 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -297,6 +297,30 @@ struct kobj_type ktype_part = {
         .sysfs_ops      = &part_sysfs_ops,
 };
 
+#ifdef CONFIG_SYSFS
+static inline void partition_sysfs_add_subdir(struct hd_struct *p)
+{
+        struct kobject *k;
+
+        k = kobject_get(&p->kobj);
+        p->holder_dir = kobject_add_dir(k, "holders");
+        kobject_put(k);
+}
+
+static inline void disk_sysfs_add_subdirs(struct gendisk *disk)
+{
+        struct kobject *k;
+
+        k = kobject_get(&disk->kobj);
+        disk->holder_dir = kobject_add_dir(k, "holders");
+        disk->slave_dir = kobject_add_dir(k, "slaves");
+        kobject_put(k);
+}
+#else
+#define partition_sysfs_add_subdir(x)   do { } while (0)
+#define disk_sysfs_add_subdirs(x)       do { } while (0)
+#endif
+
 void delete_partition(struct gendisk *disk, int part)
 {
         struct hd_struct *p = disk->part[part-1];
@@ -310,6 +334,10 @@ void delete_partition(struct gendisk *disk, int part)
         p->ios[0] = p->ios[1] = 0;
         p->sectors[0] = p->sectors[1] = 0;
         devfs_remove("%s/part%d", disk->devfs_name, part);
+#ifdef CONFIG_SYSFS
+        if (p->holder_dir)
+                kobject_unregister(p->holder_dir);
+#endif
         kobject_unregister(&p->kobj);
 }
 
@@ -337,6 +365,7 @@ void add_partition(struct gendisk *disk, int part, sector_t start, sector_t len)
         p->kobj.parent = &disk->kobj;
         p->kobj.ktype = &ktype_part;
         kobject_register(&p->kobj);
+        partition_sysfs_add_subdir(p);
         disk->part[part-1] = p;
 }
 
@@ -383,6 +412,7 @@ void register_disk(struct gendisk *disk)
         if ((err = kobject_add(&disk->kobj)))
                 return;
         disk_sysfs_symlinks(disk);
+        disk_sysfs_add_subdirs(disk);
         kobject_uevent(&disk->kobj, KOBJ_ADD);
 
         /* No minors to use for partitions */
@@ -483,6 +513,12 @@ void del_gendisk(struct gendisk *disk)
 
         devfs_remove_disk(disk);
 
+#ifdef CONFIG_SYSFS
+        if (disk->holder_dir)
+                kobject_unregister(disk->holder_dir);
+        if (disk->slave_dir)
+                kobject_unregister(disk->slave_dir);
+#endif
         if (disk->driverfs_dev) {
                 char *disk_name = make_block_name(disk);
                 sysfs_remove_link(&disk->kobj, "device");
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index fd647fde5ec..eea61cc8fac 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -78,6 +78,9 @@ struct hd_struct {
         sector_t start_sect;
         sector_t nr_sects;
         struct kobject kobj;
+#ifdef CONFIG_SYSFS
+        struct kobject *holder_dir;
+#endif
         unsigned ios[2], sectors[2];    /* READs and WRITEs */
         int policy, partno;
 };
@@ -114,6 +117,10 @@ struct gendisk {
         int number;                     /* more of the same */
         struct device *driverfs_dev;
         struct kobject kobj;
+#ifdef CONFIG_SYSFS
+        struct kobject *holder_dir;
+        struct kobject *slave_dir;
+#endif
 
         struct timer_rand_state *random;
         int policy;