[PATCH 11/12] Btrfs: sysfs: move super_kobj and device_dir_kobj from fs_info to btrfs_fs_devices

[Anand Jain <anand.jain@oracle.com>]

This patch will provide a framework and help to create attributes
from the structure btrfs_fs_devices which are available even before
fs_info is created. So by moving the parent kobject super_kobj from
fs_info to btrfs_fs_devices, it will help to create attributes
from the btrfs_fs_devices as well.

Patches on top of this patch now will be able to create the
sys/fs/btrfs/fsid kobject and attributes from btrfs_fs_devices
when devices are scanned and registered to the kernel.

Just to note, this does not change any of the existing btrfs sysfs
external kobject names and its attributes and not even the life
cycle of them. Changes are internal only. And to ensure the same,
this path has been tested with various device operations and,
checking and comparing the sysfs kobjects and attributes with
sysfs kobject and attributes with out this patch, and they remain
same.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/ctree.h   |  3 --
 fs/btrfs/sysfs.c   | 88 ++++++++++++++++++++++++++++++------------------------
 fs/btrfs/volumes.c |  3 +-
 fs/btrfs/volumes.h |  5 ++++
 4 files changed, 56 insertions(+), 43 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 85c697d..ef66d13 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1584,10 +1584,7 @@ struct btrfs_fs_info {
 	struct task_struct *cleaner_kthread;
 	int thread_pool_size;
 
-	struct kobject super_kobj;
 	struct kobject *space_info_kobj;
-	struct kobject *device_dir_kobj;
-	struct completion kobj_unregister;
 	int do_barriers;
 	int closing;
 	int log_root_recovering;
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 2cb4c69..ac15fbb 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -33,6 +33,7 @@
 #include "volumes.h"
 
 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
+static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj);
 
 static u64 get_features(struct btrfs_fs_info *fs_info,
 			enum btrfs_feature_set set)
@@ -438,10 +439,10 @@ static const struct attribute *btrfs_attrs[] = {
 
 static void btrfs_release_super_kobj(struct kobject *kobj)
 {
-	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+	struct btrfs_fs_devices *fs_devs = to_fs_devs(kobj);
 
-	memset(&fs_info->super_kobj, 0, sizeof(struct kobject));
-	complete(&fs_info->kobj_unregister);
+	memset(&fs_devs->super_kobj, 0, sizeof(struct kobject));
+	complete(&fs_devs->kobj_unregister);
 }
 
 static struct kobj_type btrfs_ktype = {
@@ -449,11 +450,18 @@ static struct kobj_type btrfs_ktype = {
 	.release	= btrfs_release_super_kobj,
 };
 
+static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj)
+{
+	if (kobj->ktype != &btrfs_ktype)
+		return NULL;
+	return container_of(kobj, struct btrfs_fs_devices, super_kobj);
+}
+
 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
 {
 	if (kobj->ktype != &btrfs_ktype)
 		return NULL;
-	return container_of(kobj, struct btrfs_fs_info, super_kobj);
+	return to_fs_devs(kobj)->fs_info;
 }
 
 #define NUM_FEATURE_BITS 64
@@ -494,12 +502,12 @@ static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
 			attrs[0] = &fa->kobj_attr.attr;
 			if (add) {
 				int ret;
-				ret = sysfs_merge_group(&fs_info->super_kobj,
+				ret = sysfs_merge_group(&fs_info->fs_devices->super_kobj,
 							&agroup);
 				if (ret)
 					return ret;
 			} else
-				sysfs_unmerge_group(&fs_info->super_kobj,
+				sysfs_unmerge_group(&fs_info->fs_devices->super_kobj,
 						    &agroup);
 		}
 
@@ -507,18 +515,17 @@ static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
 	return 0;
 }
 
-static void btrfs_sysfs_remove_fsid(struct btrfs_fs_info *fs_info)
+static void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 {
-	if (fs_info->device_dir_kobj) {
-		btrfs_kobj_rm_device(fs_info, NULL);
-		kobject_del(fs_info->device_dir_kobj);
-		kobject_put(fs_info->device_dir_kobj);
-		fs_info->device_dir_kobj = NULL;
+	if (fs_devs->device_dir_kobj) {
+		kobject_del(fs_devs->device_dir_kobj);
+		kobject_put(fs_devs->device_dir_kobj);
+		fs_devs->device_dir_kobj = NULL;
 	}
 
-	kobject_del(&fs_info->super_kobj);
-	kobject_put(&fs_info->super_kobj);
-	wait_for_completion(&fs_info->kobj_unregister);
+	kobject_del(&fs_devs->super_kobj);
+	kobject_put(&fs_devs->super_kobj);
+	wait_for_completion(&fs_devs->kobj_unregister);
 }
 
 void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
@@ -529,9 +536,10 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 		kobject_put(fs_info->space_info_kobj);
 	}
 	addrm_unknown_feature_attrs(fs_info, false);
-	sysfs_remove_group(&fs_info->super_kobj, &btrfs_feature_attr_group);
-	sysfs_remove_files(&fs_info->super_kobj, btrfs_attrs);
-	btrfs_sysfs_remove_fsid(fs_info);
+	sysfs_remove_group(&fs_info->fs_devices->super_kobj, &btrfs_feature_attr_group);
+	sysfs_remove_files(&fs_info->fs_devices->super_kobj, btrfs_attrs);
+	btrfs_kobj_rm_device(fs_info, NULL);
+	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
 }
 
 const char * const btrfs_feature_set_names[3] = {
@@ -617,14 +625,14 @@ int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
 	struct hd_struct *disk;
 	struct kobject *disk_kobj;
 
-	if (!fs_info->device_dir_kobj)
+	if (!fs_info->fs_devices->device_dir_kobj)
 		return -EINVAL;
 
 	if (one_device && one_device->bdev) {
 		disk = one_device->bdev->bd_part;
 		disk_kobj = &part_to_dev(disk)->kobj;
 
-		sysfs_remove_link(fs_info->device_dir_kobj,
+		sysfs_remove_link(fs_info->fs_devices->device_dir_kobj,
 						disk_kobj->name);
 	}
 
@@ -638,20 +646,20 @@ int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
 		disk = one_device->bdev->bd_part;
 		disk_kobj = &part_to_dev(disk)->kobj;
 
-		sysfs_remove_link(fs_info->device_dir_kobj,
+		sysfs_remove_link(fs_info->fs_devices->device_dir_kobj,
 						disk_kobj->name);
 	}
 
 	return 0;
 }
 
-int btrfs_sysfs_add_device(struct btrfs_fs_info *fs_info)
+int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs)
 {
-	if (!fs_info->device_dir_kobj)
-		fs_info->device_dir_kobj = kobject_create_and_add("devices",
-						&fs_info->super_kobj);
+	if (!fs_devs->device_dir_kobj)
+		fs_devs->device_dir_kobj = kobject_create_and_add("devices",
+						&fs_devs->super_kobj);
 
-	if (!fs_info->device_dir_kobj)
+	if (!fs_devs->device_dir_kobj)
 		return -ENOMEM;
 
 	return 0;
@@ -664,7 +672,7 @@ int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	struct btrfs_device *dev;
 
-	error = btrfs_sysfs_add_device(fs_info);
+	error = btrfs_sysfs_add_device(fs_devices);
 	if (error)
 		return error;
 
@@ -681,7 +689,7 @@ int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
 		disk = dev->bdev->bd_part;
 		disk_kobj = &part_to_dev(disk)->kobj;
 
-		error = sysfs_create_link(fs_info->device_dir_kobj,
+		error = sysfs_create_link(fs_devices->device_dir_kobj,
 					  disk_kobj, disk_kobj->name);
 		if (error)
 			break;
@@ -703,39 +711,41 @@ u64 btrfs_debugfs_test;
  * Can be called by the device discovery thread.
  * And parent can be specified for seed device
  */
-int btrfs_sysfs_add_fsid(struct btrfs_fs_info *fs_info,
+static int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
 				struct kobject *parent)
 {
 	int error;
 
-	init_completion(&fs_info->kobj_unregister);
-	fs_info->super_kobj.kset = btrfs_kset;
-	error = kobject_init_and_add(&fs_info->super_kobj, &btrfs_ktype, NULL,
-				     "%pU", fs_info->fsid);
+	init_completion(&fs_devs->kobj_unregister);
+	fs_devs->super_kobj.kset = btrfs_kset;
+	error = kobject_init_and_add(&fs_devs->super_kobj, &btrfs_ktype, NULL,
+				     "%pU", fs_devs->fsid);
 	return error;
 }
 
 int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 {
 	int error;
+	struct btrfs_fs_devices *fs_devs = fs_info->fs_devices;
+	struct kobject *super_kobj = &fs_devs->super_kobj;
 
-	error = btrfs_sysfs_add_fsid(fs_info, NULL);
+	error = btrfs_sysfs_add_fsid(fs_devs, NULL);
 	if (error)
 		return error;
 
 	error = btrfs_kobj_add_device(fs_info, NULL);
 	if (error) {
-		btrfs_sysfs_remove_fsid(fs_info);
+		btrfs_sysfs_remove_fsid(fs_devs);
 		return error;
 	}
 
-	error = sysfs_create_files(&fs_info->super_kobj, btrfs_attrs);
+	error = sysfs_create_files(super_kobj, btrfs_attrs);
 	if (error) {
-		btrfs_sysfs_remove_fsid(fs_info);
+		btrfs_sysfs_remove_fsid(fs_devs);
 		return error;
 	}
 
-	error = sysfs_create_group(&fs_info->super_kobj,
+	error = sysfs_create_group(super_kobj,
 				   &btrfs_feature_attr_group);
 	if (error)
 		goto failure;
@@ -745,7 +755,7 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 		goto failure;
 
 	fs_info->space_info_kobj = kobject_create_and_add("allocation",
-						  &fs_info->super_kobj);
+						  super_kobj);
 	if (!fs_info->space_info_kobj) {
 		error = -ENOMEM;
 		goto failure;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index da7e0e1..6bbee64 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2243,7 +2243,8 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 		 */
 		snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU",
 						root->fs_info->fsid);
-		if (kobject_rename(&root->fs_info->super_kobj, fsid_buf))
+		if (kobject_rename(&root->fs_info->fs_devices->super_kobj,
+								fsid_buf))
 			goto error_trans;
 	}
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 83069de..a1df344 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -253,6 +253,11 @@ struct btrfs_fs_devices {
 	 * nonrot flag set
 	 */
 	int rotating;
+
+	/* sysfs kobjects */
+	struct kobject super_kobj;
+	struct kobject *device_dir_kobj;
+	struct completion kobj_unregister;
 };
 
 #define BTRFS_BIO_INLINE_CSUM_SIZE	64
-- 
1.9.1