[PATCH 71/78] block: add a bdev_kobj helper

[Christoph Hellwig <hch@xxxxxx>]

Add a little helper to find the kobject for a struct block_device.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 drivers/md/bcache/super.c |  7 ++-----
 drivers/md/md.c           |  4 +---
 fs/btrfs/sysfs.c          | 15 +++------------
 include/linux/blk_types.h |  3 +++
 4 files changed, 9 insertions(+), 20 deletions(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index ea2b80c3e44c38..f6edacc81527c7 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1447,8 +1447,7 @@ static int register_bdev(struct cache_sb *sb, struct 
cache_sb_disk *sb_disk,
                goto err;
 
        err = "error creating kobject";
-       if (kobject_add(&dc->disk.kobj, &part_to_dev(bdev->bd_part)->kobj,
-                       "bcache"))
+       if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
                goto err;
        if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
                goto err;
@@ -2342,9 +2341,7 @@ static int register_cache(struct cache_sb *sb, struct 
cache_sb_disk *sb_disk,
                goto err;
        }
 
-       if (kobject_add(&ca->kobj,
-                       &part_to_dev(bdev->bd_part)->kobj,
-                       "bcache")) {
+       if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
                err = "error calling kobject_add";
                ret = -ENOMEM;
                goto out;
diff --git a/drivers/md/md.c b/drivers/md/md.c
index b2edf5e0f965b5..7ce6047c856ea2 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2414,7 +2414,6 @@ EXPORT_SYMBOL(md_integrity_add_rdev);
 static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
 {
        char b[BDEVNAME_SIZE];
-       struct kobject *ko;
        int err;
 
        /* prevent duplicates */
@@ -2477,9 +2476,8 @@ static int bind_rdev_to_array(struct md_rdev *rdev, 
struct mddev *mddev)
        if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
                goto fail;
 
-       ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
        /* failure here is OK */
-       err = sysfs_create_link(&rdev->kobj, ko, "block");
+       err = sysfs_create_link(&rdev->kobj, bdev_kobj(rdev->bdev), "block");
        rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
        rdev->sysfs_unack_badblocks =
                sysfs_get_dirent_safe(rdev->kobj.sd, 
"unacknowledged_bad_blocks");
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 279d9262b676d4..24b6c6dc69000a 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -1232,8 +1232,6 @@ int btrfs_sysfs_add_space_info_type(struct btrfs_fs_info 
*fs_info,
 
 void btrfs_sysfs_remove_device(struct btrfs_device *device)
 {
-       struct hd_struct *disk;
-       struct kobject *disk_kobj;
        struct kobject *devices_kobj;
 
        /*
@@ -1243,11 +1241,8 @@ void btrfs_sysfs_remove_device(struct btrfs_device 
*device)
        devices_kobj = device->fs_info->fs_devices->devices_kobj;
        ASSERT(devices_kobj);
 
-       if (device->bdev) {
-               disk = device->bdev->bd_part;
-               disk_kobj = &part_to_dev(disk)->kobj;
-               sysfs_remove_link(devices_kobj, disk_kobj->name);
-       }
+       if (device->bdev)
+               sysfs_remove_link(devices_kobj, bdev_kobj(device->bdev)->name);
 
        if (device->devid_kobj.state_initialized) {
                kobject_del(&device->devid_kobj);
@@ -1353,11 +1348,7 @@ int btrfs_sysfs_add_device(struct btrfs_device *device)
        nofs_flag = memalloc_nofs_save();
 
        if (device->bdev) {
-               struct hd_struct *disk;
-               struct kobject *disk_kobj;
-
-               disk = device->bdev->bd_part;
-               disk_kobj = &part_to_dev(disk)->kobj;
+               struct kobject *disk_kobj = bdev_kobj(device->bdev);
 
                ret = sysfs_create_link(devices_kobj, disk_kobj, 
disk_kobj->name);
                if (ret) {
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 0735e335ca6c0a..5a5ccacb804cdb 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -49,6 +49,9 @@ struct block_device {
 #define bdev_whole(_bdev) \
        ((_bdev)->bd_disk->part0.bdev)
 
+#define bdev_kobj(_bdev) \
+       (&part_to_dev((_bdev)->bd_part)->kobj)
+
 /*
  * Block error status values.  See block/blk-core:blk_errors for the details.
  * Alpha cannot write a byte atomically, so we need to use 32-bit value.
-- 
2.29.2