[PATCH 00/27 V5] provide framework so that sysfs attributs from the fs_devices can be added

[PATCH 00/27 V5] provide framework so that sysfs attributs from the fs_devices can be added

[Anand Jain]

This patch set 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.
    
Just to note, patch 01 to 26 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. The test script test-btrfs-devmgt.sh can be found in the ml.
Patch 27, makes two kobjects fsid and devices to be created during
the device scan, however their attributes will continue to be created
at the mount as original.

v4->v5:
  . add kobject_move patch 01/27
  . commit corrections where necessary
  . the individual patch version is not updated and I am maintaining
    the patch set version as v5.

v3->v4:
  . reorders the patches
  . accepts Dave comment
  . needed stale device clean up, introduced patch..
	520353e Btrfs: free the stale device
  . added cleanups to the patch to support seeding in the patch..
	e311d0a Btrfs: sysfs: support seed devices in the sysfs layout v3
  . added support to show replacing target on the sysfs in the patch..
	e210d55 Btrfs: sysfs: add support to show replacing target in the sysfs

v2->v3:
  . added missing signed-off
  . Dave comment
  . there isn't v2 for individual patch, I marked individual patch v3
    where necessary
v1->v2:
  . adds fresh set of patches from 12 to 24 to support seed fsids
  on btrfs sysfs layout and the related frame work changes
  . the patches 1 to 12 has no changes from the previous submit


Anand Jain (27):
  export symbol kobject_move()
  Btrfs: sysfs: fix, btrfs_release_super_kobj() should to clean up the
    kobject data
  Btrfs: sysfs: fix, fs_info kobject_unregister has init_completion()
    twice
  Btrfs: sysfs: fix, undo sysfs device links
  Btrfs: sysfs: fix, kobject pointer clean up needed after kobject
    release
  Btrfc: sysfs: fix, check if device_dir_kobj is init before destroy
  Btrfs: sysfs: reorder the kobject creations
  Btrfs: sysfs: rename __btrfs_sysfs_remove_one to
    btrfs_sysfs_remove_fsid
  Btrfs: sysfs: introduce function btrfs_sysfs_add_fsid() to create
    sysfs fsid
  Btrfs: sysfs: let default_attrs be separate from the kset
  Btrfs: sysfs: separate device kobject and its attribute creation
  Btrfs: sysfs: move super_kobj and device_dir_kobj from fs_info to
    btrfs_fs_devices
  Btrfs: introduce btrfs_get_fs_uuids to get fs_uuids
  Btrfs: sysfs: add pointer to access fs_info from fs_devices
  Btrfs: sysfs: provide framework to remove all fsid sysfs kobject
  Btrfs: sysfs btrfs_kobj_add_device() pass fs_devices instead of
    fs_info
  Btrfs: sysfs btrfs_kobj_rm_device() pass fs_devices instead of fs_info
  Btrfs: sysfs: make btrfs_sysfs_add_fsid() non static
  Btrfs: sysfs: make btrfs_sysfs_add_device() non static
  Btrfs: sysfs: btrfs_sysfs_remove_fsid() make it non static
  Btrfs: sysfs: separate kobject and attribute creation
  Btrfs: sysfs: add support to add parent for fsid
  Btrfs: sysfs: don't fail seeding for the sake of sysfs kobject issue
  Btrfs: free the stale device
  Btrfs: sysfs: add support to show replacing target in the sysfs
  Btrfs: sysfs: support seed devices in the sysfs layout
  Btrfs: create sys/fs/btrfs/fsid when scanned instead of when mounted

 fs/btrfs/ctree.h       |   7 +-
 fs/btrfs/dev-replace.c |   7 +-
 fs/btrfs/disk-io.c     |  26 ++++-
 fs/btrfs/sysfs.c       | 266 +++++++++++++++++++++++++++++++++++++++----------
 fs/btrfs/sysfs.h       |  15 ++-
 fs/btrfs/volumes.c     |  99 +++++++++++++++---
 fs/btrfs/volumes.h     |   9 ++
 lib/kobject.c          |   1 +
 8 files changed, 346 insertions(+), 84 deletions(-)

-- 
2.0.0.153.g79dcccc

[PATCH 01/27] export symbol kobject_move()

[Anand Jain]

drivers/cpufreq/cpufreq.c is already using this function. And now btrfs
needs it as well. export symbol kobject_move().

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 lib/kobject.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/kobject.c b/lib/kobject.c
index 58751bb..e055c06 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -548,6 +548,7 @@ out:
 	kfree(devpath);
 	return error;
 }
+EXPORT_SYMBOL_GPL(kobject_move);
 
 /**
  * kobject_del - unlink kobject from hierarchy.
-- 
2.0.0.153.g79dcccc

[PATCH 02/27] Btrfs: sysfs: fix, btrfs_release_super_kobj() should to clean up the kobject data

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

The following test case fails indicating that, thread tried to init an initialized object.

kernel: [232104.016513] kobject (ffff880006c1c980): tried to init an initialized object, something is seriously wrong.

btrfs_sysfs_remove_one() self test code:

open_tree()
{
 ::
        ret = btrfs_sysfs_add_one(fs_info);
	if (ret) {
              pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
                goto fail_block_groups;
        }
+       btrfs_sysfs_remove_one(fs_info);
+       ret = btrfs_sysfs_add_one(fs_info);
+       if (ret) {
+               pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
+               goto fail_block_groups;
+       }

cleaning up the unregistered kobject fixes this.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 92db3f6..68dcd17 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -439,6 +439,8 @@ static struct attribute *btrfs_attrs[] = {
 static void btrfs_release_super_kobj(struct kobject *kobj)
 {
 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+
+	memset(&fs_info->super_kobj, 0, sizeof(struct kobject));
 	complete(&fs_info->kobj_unregister);
 }
 
-- 
2.0.0.153.g79dcccc

[PATCH 03/27] Btrfs: sysfs: fix, fs_info kobject_unregister has init_completion() twice

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

kobject_unregister is to handle the release of the kobject,
its completion init is being called in btrfs_sysfs_add_one(),
so we don't have to do the same in the open_ctree() again.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/disk-io.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8c63419..0cd6550 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2238,7 +2238,6 @@ int open_ctree(struct super_block *sb,
 	mutex_init(&fs_info->delalloc_root_mutex);
 	seqlock_init(&fs_info->profiles_lock);
 
-	init_completion(&fs_info->kobj_unregister);
 	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
 	INIT_LIST_HEAD(&fs_info->space_info);
 	INIT_LIST_HEAD(&fs_info->tree_mod_seq_list);
-- 
2.0.0.153.g79dcccc

[PATCH 04/27] Btrfs: sysfs: fix, undo sysfs device links

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Theoritically need to remove the device links attributes, but since its entire device
kobject was removed, so there wasn't any issue of about it. Just do it nicely.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 68dcd17..adfac3e 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -522,6 +522,7 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 		kobject_del(fs_info->space_info_kobj);
 		kobject_put(fs_info->space_info_kobj);
 	}
+	btrfs_kobj_rm_device(fs_info, NULL);
 	kobject_del(fs_info->device_dir_kobj);
 	kobject_put(fs_info->device_dir_kobj);
 	addrm_unknown_feature_attrs(fs_info, false);
@@ -604,6 +605,8 @@ static void init_feature_attrs(void)
 	}
 }
 
+/* when one_device is NULL, it removes all device links */
+
 int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
 		struct btrfs_device *one_device)
 {
@@ -621,6 +624,20 @@ int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
 						disk_kobj->name);
 	}
 
+	if (one_device)
+		return 0;
+
+	list_for_each_entry(one_device,
+			&fs_info->fs_devices->devices, dev_list) {
+		if (!one_device->bdev)
+			continue;
+		disk = one_device->bdev->bd_part;
+		disk_kobj = &part_to_dev(disk)->kobj;
+
+		sysfs_remove_link(fs_info->device_dir_kobj,
+						disk_kobj->name);
+	}
+
 	return 0;
 }
 
-- 
2.0.0.153.g79dcccc

[PATCH 05/27] Btrfs: sysfs: fix, kobject pointer clean up needed after kobject release

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

The sysfs clean up self test like in the below code fails, since
fs_info->device_dir_kobject still points to its stale kobject.
Reseting this pointer will help to fix this.

open_ctree()
{

ret = btrfs_sysfs_add_one(fs_info);
::
+       btrfs_sysfs_remove_one(fs_info);
+       ret = btrfs_sysfs_add_one(fs_info);
+       if (ret) {
+               pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
+               goto fail_block_groups;
+       }

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index adfac3e..15fead2 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -525,6 +525,7 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 	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;
 	addrm_unknown_feature_attrs(fs_info, false);
 	sysfs_remove_group(&fs_info->super_kobj, &btrfs_feature_attr_group);
 	__btrfs_sysfs_remove_one(fs_info);
-- 
2.0.0.153.g79dcccc

[PATCH 06/27] Btrfc: sysfs: fix, check if device_dir_kobj is init before destroy

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Since the failure code in the btrfs_sysfs_add_one() can
call btrfs_sysfs_remove_one() even before device_dir_kobj
has been created we need to check if its null.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 15fead2..506f7e4 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -522,10 +522,12 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 		kobject_del(fs_info->space_info_kobj);
 		kobject_put(fs_info->space_info_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_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;
+	}
 	addrm_unknown_feature_attrs(fs_info, false);
 	sysfs_remove_group(&fs_info->super_kobj, &btrfs_feature_attr_group);
 	__btrfs_sysfs_remove_one(fs_info);
-- 
2.0.0.153.g79dcccc

[PATCH 07/27] Btrfs: sysfs: reorder the kobject creations

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

As of now the order in which the kobjects are created
at btrfs_sysfs_add_one() is..
 fsid
 features
 unknown features (dynamic features)
 devices.

Since we would move fsid and device kobject to fs_devices
from fs_info structure, this patch will reorder in which
the kobjects are created as below.
 fsid
 devices
 features
 unknown features (dynamic features)

And hence the btrfs_sysfs_remove_one() will follow the same
in reverse order. and the device kobject destroy now can
be moved into the function __btrfs_sysfs_remove_one()

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 506f7e4..c3e7f06 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -510,6 +510,13 @@ static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
 
 static void __btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 {
+	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;
+	}
+
 	kobject_del(&fs_info->super_kobj);
 	kobject_put(&fs_info->super_kobj);
 	wait_for_completion(&fs_info->kobj_unregister);
@@ -522,12 +529,6 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 		kobject_del(fs_info->space_info_kobj);
 		kobject_put(fs_info->space_info_kobj);
 	}
-	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;
-	}
 	addrm_unknown_feature_attrs(fs_info, false);
 	sysfs_remove_group(&fs_info->super_kobj, &btrfs_feature_attr_group);
 	__btrfs_sysfs_remove_one(fs_info);
@@ -700,6 +701,12 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 	if (error)
 		return error;
 
+	error = btrfs_kobj_add_device(fs_info, NULL);
+	if (error) {
+		__btrfs_sysfs_remove_one(fs_info);
+		return error;
+	}
+
 	error = sysfs_create_group(&fs_info->super_kobj,
 				   &btrfs_feature_attr_group);
 	if (error) {
@@ -711,10 +718,6 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 	if (error)
 		goto failure;
 
-	error = btrfs_kobj_add_device(fs_info, NULL);
-	if (error)
-		goto failure;
-
 	fs_info->space_info_kobj = kobject_create_and_add("allocation",
 						  &fs_info->super_kobj);
 	if (!fs_info->space_info_kobj) {
-- 
2.0.0.153.g79dcccc

[PATCH 08/27] Btrfs: sysfs: rename __btrfs_sysfs_remove_one to btrfs_sysfs_remove_fsid

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index c3e7f06..c923e8b 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -508,7 +508,7 @@ static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
 	return 0;
 }
 
-static void __btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
+static void btrfs_sysfs_remove_fsid(struct btrfs_fs_info *fs_info)
 {
 	if (fs_info->device_dir_kobj) {
 		btrfs_kobj_rm_device(fs_info, NULL);
@@ -531,7 +531,7 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 	}
 	addrm_unknown_feature_attrs(fs_info, false);
 	sysfs_remove_group(&fs_info->super_kobj, &btrfs_feature_attr_group);
-	__btrfs_sysfs_remove_one(fs_info);
+	btrfs_sysfs_remove_fsid(fs_info);
 }
 
 const char * const btrfs_feature_set_names[3] = {
@@ -703,14 +703,14 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 
 	error = btrfs_kobj_add_device(fs_info, NULL);
 	if (error) {
-		__btrfs_sysfs_remove_one(fs_info);
+		btrfs_sysfs_remove_fsid(fs_info);
 		return error;
 	}
 
 	error = sysfs_create_group(&fs_info->super_kobj,
 				   &btrfs_feature_attr_group);
 	if (error) {
-		__btrfs_sysfs_remove_one(fs_info);
+		btrfs_sysfs_remove_fsid(fs_info);
 		return error;
 	}
 
-- 
2.0.0.153.g79dcccc

[PATCH 09/27] Btrfs: sysfs: introduce function btrfs_sysfs_add_fsid() to create sysfs fsid

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

We need it in a seperate function so that it can be called from the
device discovery thread as well.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index c923e8b..f42d8fd 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -690,7 +690,12 @@ static struct dentry *btrfs_debugfs_root_dentry;
 /* Debugging tunables and exported data */
 u64 btrfs_debugfs_test;
 
-int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
+/*
+ * 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,
+				struct kobject *parent)
 {
 	int error;
 
@@ -698,6 +703,14 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 	fs_info->super_kobj.kset = btrfs_kset;
 	error = kobject_init_and_add(&fs_info->super_kobj, &btrfs_ktype, NULL,
 				     "%pU", fs_info->fsid);
+	return error;
+}
+
+int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
+{
+	int error;
+
+	error = btrfs_sysfs_add_fsid(fs_info, NULL);
 	if (error)
 		return error;
 
-- 
2.0.0.153.g79dcccc

[PATCH 10/27] Btrfs: sysfs: let default_attrs be separate from the kset

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

As of now btrfs_attrs are provided using the default_attrs through
the kset. Separate them and create the default_attrs using the
sysfs_create_files instead. By doing this we will have the
flexibility that device discovery thread could create fsid
kobject.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index f42d8fd..5208a49 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -428,7 +428,7 @@ static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
 
 BTRFS_ATTR(clone_alignment, btrfs_clone_alignment_show);
 
-static struct attribute *btrfs_attrs[] = {
+static const struct attribute *btrfs_attrs[] = {
 	BTRFS_ATTR_PTR(label),
 	BTRFS_ATTR_PTR(nodesize),
 	BTRFS_ATTR_PTR(sectorsize),
@@ -447,7 +447,6 @@ static void btrfs_release_super_kobj(struct kobject *kobj)
 static struct kobj_type btrfs_ktype = {
 	.sysfs_ops	= &kobj_sysfs_ops,
 	.release	= btrfs_release_super_kobj,
-	.default_attrs	= btrfs_attrs,
 };
 
 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
@@ -531,6 +530,7 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 	}
 	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);
 }
 
@@ -720,13 +720,17 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 		return error;
 	}
 
-	error = sysfs_create_group(&fs_info->super_kobj,
-				   &btrfs_feature_attr_group);
+	error = sysfs_create_files(&fs_info->super_kobj, btrfs_attrs);
 	if (error) {
 		btrfs_sysfs_remove_fsid(fs_info);
 		return error;
 	}
 
+	error = sysfs_create_group(&fs_info->super_kobj,
+				   &btrfs_feature_attr_group);
+	if (error)
+		goto failure;
+
 	error = addrm_unknown_feature_attrs(fs_info, true);
 	if (error)
 		goto failure;
-- 
2.0.0.153.g79dcccc

[PATCH 11/27] Btrfs: sysfs: separate device kobject and its attribute creation

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Separate device kobject and its attribute creation so that device
kobject can be created from the device discovery thread.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 5208a49..2cb4c69 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -645,13 +645,8 @@ int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
 	return 0;
 }
 
-int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
-		struct btrfs_device *one_device)
+int btrfs_sysfs_add_device(struct btrfs_fs_info *fs_info)
 {
-	int error = 0;
-	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
-	struct btrfs_device *dev;
-
 	if (!fs_info->device_dir_kobj)
 		fs_info->device_dir_kobj = kobject_create_and_add("devices",
 						&fs_info->super_kobj);
@@ -659,6 +654,20 @@ int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
 	if (!fs_info->device_dir_kobj)
 		return -ENOMEM;
 
+	return 0;
+}
+
+int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
+		struct btrfs_device *one_device)
+{
+	int error = 0;
+	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+	struct btrfs_device *dev;
+
+	error = btrfs_sysfs_add_device(fs_info);
+	if (error)
+		return error;
+
 	list_for_each_entry(dev, &fs_devices->devices, dev_list) {
 		struct hd_struct *disk;
 		struct kobject *disk_kobj;
-- 
2.0.0.153.g79dcccc

[PATCH 12/27] Btrfs: sysfs: move super_kobj and device_dir_kobj from fs_info to btrfs_fs_devices

[Anand Jain]

From: 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 7e60741..9493b91 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1580,10 +1580,7 @@ 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 0144790..218a14a 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 d6fe73c..c2e5bd0 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
-- 
2.0.0.153.g79dcccc

[PATCH 13/27] Btrfs: introduce btrfs_get_fs_uuids to get fs_uuids

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 4 ++++
 fs/btrfs/volumes.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 218a14a..c1b1038 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -52,6 +52,10 @@ static void btrfs_dev_stat_print_on_load(struct btrfs_device *device);
 
 DEFINE_MUTEX(uuid_mutex);
 static LIST_HEAD(fs_uuids);
+struct list_head *btrfs_get_fs_uuids(void)
+{
+	return &fs_uuids;
+}
 
 static struct btrfs_fs_devices *__alloc_fs_devices(void)
 {
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index c2e5bd0..d4586ac 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -539,5 +539,6 @@ static inline void unlock_chunks(struct btrfs_root *root)
 	mutex_unlock(&root->fs_info->chunk_mutex);
 }
 
+struct list_head *btrfs_get_fs_uuids(void);
 
 #endif
-- 
2.0.0.153.g79dcccc

[PATCH 14/27] Btrfs: sysfs: add pointer to access fs_info from fs_devices

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

adds fs_info pointer with struct btrfs_fs_devices.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c   |  4 ++++
 fs/btrfs/volumes.c | 18 ++++++++++++++++++
 fs/btrfs/volumes.h |  3 +++
 3 files changed, 25 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index ac15fbb..95d6257 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -530,6 +530,8 @@ static void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 
 void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 {
+	btrfs_reset_fs_info_ptr(fs_info);
+
 	if (fs_info->space_info_kobj) {
 		sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
 		kobject_del(fs_info->space_info_kobj);
@@ -729,6 +731,8 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 	struct btrfs_fs_devices *fs_devs = fs_info->fs_devices;
 	struct kobject *super_kobj = &fs_devs->super_kobj;
 
+	btrfs_set_fs_info_ptr(fs_info);
+
 	error = btrfs_sysfs_add_fsid(fs_devs, NULL);
 	if (error)
 		return error;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c1b1038..033e56a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6688,3 +6688,21 @@ void btrfs_update_commit_device_bytes_used(struct btrfs_root *root,
 	}
 	unlock_chunks(root);
 }
+
+void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+	while (fs_devices) {
+		fs_devices->fs_info = fs_info;
+		fs_devices = fs_devices->seed;
+	}
+}
+
+void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+	while (fs_devices) {
+		fs_devices->fs_info = NULL;
+		fs_devices = fs_devices->seed;
+	}
+}
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index d4586ac..e6514c7 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -254,6 +254,7 @@ struct btrfs_fs_devices {
 	 */
 	int rotating;
 
+	struct btrfs_fs_info *fs_info;
 	/* sysfs kobjects */
 	struct kobject super_kobj;
 	struct kobject *device_dir_kobj;
@@ -540,5 +541,7 @@ static inline void unlock_chunks(struct btrfs_root *root)
 }
 
 struct list_head *btrfs_get_fs_uuids(void);
+void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info);
+void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info);
 
 #endif
-- 
2.0.0.153.g79dcccc

[PATCH 15/27] Btrfs: sysfs: provide framework to remove all fsid sysfs kobject

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

just a helper function to clean up the sysfs fsid kobjects

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 95d6257..a8ee136 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -515,7 +515,7 @@ 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_devices *fs_devs)
+static void __btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 {
 	if (fs_devs->device_dir_kobj) {
 		kobject_del(fs_devs->device_dir_kobj);
@@ -528,6 +528,21 @@ static void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 	wait_for_completion(&fs_devs->kobj_unregister);
 }
 
+/* when fs_devs is NULL it will remove all fsid kobject */
+static void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
+{
+	struct list_head *fs_uuids = btrfs_get_fs_uuids();
+
+	if (fs_devs) {
+		__btrfs_sysfs_remove_fsid(fs_devs);
+		return;
+	}
+
+	list_for_each_entry(fs_devs, fs_uuids, list) {
+		__btrfs_sysfs_remove_fsid(fs_devs);
+	}
+}
+
 void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 {
 	btrfs_reset_fs_info_ptr(fs_info);
-- 
2.0.0.153.g79dcccc

[PATCH 16/27] Btrfs: sysfs btrfs_kobj_add_device() pass fs_devices instead of fs_info

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

btrfs_kobj_add_device() does not need fs_info any more.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/dev-replace.c | 2 +-
 fs/btrfs/sysfs.c       | 7 +++----
 fs/btrfs/sysfs.h       | 2 +-
 fs/btrfs/volumes.c     | 2 +-
 4 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index ca6a3a3..2acc0aa 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -593,7 +593,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 
 	/* replace the sysfs entry */
 	btrfs_kobj_rm_device(fs_info, src_device);
-	btrfs_kobj_add_device(fs_info, tgt_device);
+	btrfs_kobj_add_device(fs_info->fs_devices, tgt_device);
 	btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 
 	/* write back the superblocks */
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index a8ee136..76afc96 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -682,11 +682,10 @@ int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs)
 	return 0;
 }
 
-int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
-		struct btrfs_device *one_device)
+int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
+				struct btrfs_device *one_device)
 {
 	int error = 0;
-	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	struct btrfs_device *dev;
 
 	error = btrfs_sysfs_add_device(fs_devices);
@@ -752,7 +751,7 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 	if (error)
 		return error;
 
-	error = btrfs_kobj_add_device(fs_info, NULL);
+	error = btrfs_kobj_add_device(fs_devs, NULL);
 	if (error) {
 		btrfs_sysfs_remove_fsid(fs_devs);
 		return error;
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index f7dd298..eeb86a8 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -70,7 +70,7 @@ char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags);
 extern const char * const btrfs_feature_set_names[3];
 extern struct kobj_type space_info_ktype;
 extern struct kobj_type btrfs_raid_ktype;
-int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
+int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
 		struct btrfs_device *one_device);
 int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
                 struct btrfs_device *one_device);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 033e56a..ee318af 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2206,7 +2206,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 				    tmp + 1);
 
 	/* add sysfs device entry */
-	btrfs_kobj_add_device(root->fs_info, device);
+	btrfs_kobj_add_device(root->fs_info->fs_devices, device);
 
 	/*
 	 * we've got more storage, clear any full flags on the space
-- 
2.0.0.153.g79dcccc

[PATCH 17/27] Btrfs: sysfs btrfs_kobj_rm_device() pass fs_devices instead of fs_info

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

since btrfs_kobj_rm_device() does nothing with fs_info

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/dev-replace.c |  2 +-
 fs/btrfs/sysfs.c       | 12 ++++++------
 fs/btrfs/sysfs.h       |  2 +-
 fs/btrfs/volumes.c     |  4 ++--
 4 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 2acc0aa..124b60f 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -592,7 +592,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	mutex_unlock(&uuid_mutex);
 
 	/* replace the sysfs entry */
-	btrfs_kobj_rm_device(fs_info, src_device);
+	btrfs_kobj_rm_device(fs_info->fs_devices, src_device);
 	btrfs_kobj_add_device(fs_info->fs_devices, tgt_device);
 	btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 76afc96..5055809 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -555,7 +555,7 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 	addrm_unknown_feature_attrs(fs_info, false);
 	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_kobj_rm_device(fs_info->fs_devices, NULL);
 	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
 }
 
@@ -636,20 +636,20 @@ static void init_feature_attrs(void)
 
 /* when one_device is NULL, it removes all device links */
 
-int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
+int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
 		struct btrfs_device *one_device)
 {
 	struct hd_struct *disk;
 	struct kobject *disk_kobj;
 
-	if (!fs_info->fs_devices->device_dir_kobj)
+	if (!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->fs_devices->device_dir_kobj,
+		sysfs_remove_link(fs_devices->device_dir_kobj,
 						disk_kobj->name);
 	}
 
@@ -657,13 +657,13 @@ int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
 		return 0;
 
 	list_for_each_entry(one_device,
-			&fs_info->fs_devices->devices, dev_list) {
+			&fs_devices->devices, dev_list) {
 		if (!one_device->bdev)
 			continue;
 		disk = one_device->bdev->bd_part;
 		disk_kobj = &part_to_dev(disk)->kobj;
 
-		sysfs_remove_link(fs_info->fs_devices->device_dir_kobj,
+		sysfs_remove_link(fs_devices->device_dir_kobj,
 						disk_kobj->name);
 	}
 
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index eeb86a8..3938ac1 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -72,6 +72,6 @@ extern struct kobj_type space_info_ktype;
 extern struct kobj_type btrfs_raid_ktype;
 int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
 		struct btrfs_device *one_device);
-int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
+int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
                 struct btrfs_device *one_device);
 #endif /* _BTRFS_SYSFS_H_ */
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index ee318af..549f978 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1701,7 +1701,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 	if (device->bdev) {
 		device->fs_devices->open_devices--;
 		/* remove sysfs entry */
-		btrfs_kobj_rm_device(root->fs_info, device);
+		btrfs_kobj_rm_device(root->fs_info->fs_devices, device);
 	}
 
 	call_rcu(&device->rcu, free_device);
@@ -2285,7 +2285,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 error_trans:
 	btrfs_end_transaction(trans, root);
 	rcu_string_free(device->name);
-	btrfs_kobj_rm_device(root->fs_info, device);
+	btrfs_kobj_rm_device(root->fs_info->fs_devices, device);
 	kfree(device);
 error:
 	blkdev_put(bdev, FMODE_EXCL);
-- 
2.0.0.153.g79dcccc

[PATCH 18/27] Btrfs: sysfs: make btrfs_sysfs_add_fsid() non static

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 2 +-
 fs/btrfs/sysfs.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 5055809..42ed7a7 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -727,7 +727,7 @@ u64 btrfs_debugfs_test;
  * Can be called by the device discovery thread.
  * And parent can be specified for seed device
  */
-static int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
+int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
 				struct kobject *parent)
 {
 	int error;
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index 3938ac1..aaff124 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -74,4 +74,6 @@ int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
 		struct btrfs_device *one_device);
 int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
                 struct btrfs_device *one_device);
+int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
+				struct kobject *parent);
 #endif /* _BTRFS_SYSFS_H_ */
-- 
2.0.0.153.g79dcccc

[PATCH 19/27] Btrfs: sysfs: make btrfs_sysfs_add_device() non static

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index aaff124..ac06b5c 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -76,4 +76,5 @@ int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
                 struct btrfs_device *one_device);
 int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
 				struct kobject *parent);
+int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs);
 #endif /* _BTRFS_SYSFS_H_ */
-- 
2.0.0.153.g79dcccc

[PATCH 20/27] Btrfs: sysfs: btrfs_sysfs_remove_fsid() make it non static

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 2 +-
 fs/btrfs/sysfs.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 42ed7a7..1d34538 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -529,7 +529,7 @@ static void __btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 }
 
 /* when fs_devs is NULL it will remove all fsid kobject */
-static void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
+void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 {
 	struct list_head *fs_uuids = btrfs_get_fs_uuids();
 
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index ac06b5c..2b31f6f 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -77,4 +77,5 @@ int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
 int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
 				struct kobject *parent);
 int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs);
+void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs);
 #endif /* _BTRFS_SYSFS_H_ */
-- 
2.0.0.153.g79dcccc

[PATCH 21/27] Btrfs: sysfs: separate kobject and attribute creation

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/disk-io.c | 18 +++++++++++++++++-
 fs/btrfs/sysfs.c   | 15 ++-------------
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 0cd6550..4b7f3b8 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2785,10 +2785,22 @@ retry_root_backup:
 
 	btrfs_close_extra_devices(fs_info, fs_devices, 1);
 
+	ret = btrfs_sysfs_add_fsid(fs_devices, NULL);
+	if (ret) {
+		pr_err("BTRFS: failed to init sysfs fsid interface: %d\n", ret);
+		goto fail_block_groups;
+	}
+
+	ret = btrfs_sysfs_add_device(fs_devices);
+	if (ret) {
+		pr_err("BTRFS: failed to init sysfs device interface: %d\n", ret);
+		goto fail_fsdev_sysfs;
+	}
+
 	ret = btrfs_sysfs_add_one(fs_info);
 	if (ret) {
 		pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
-		goto fail_block_groups;
+		goto fail_fsdev_sysfs;
 	}
 
 	ret = btrfs_init_space_info(fs_info);
@@ -3002,6 +3014,9 @@ fail_cleaner:
 fail_sysfs:
 	btrfs_sysfs_remove_one(fs_info);
 
+fail_fsdev_sysfs:
+	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
+
 fail_block_groups:
 	btrfs_put_block_group_cache(fs_info);
 	btrfs_free_block_groups(fs_info);
@@ -3679,6 +3694,7 @@ void close_ctree(struct btrfs_root *root)
 	}
 
 	btrfs_sysfs_remove_one(fs_info);
+	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
 
 	btrfs_free_fs_roots(fs_info);
 
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 1d34538..be5342f 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -556,7 +556,6 @@ void btrfs_sysfs_remove_one(struct btrfs_fs_info *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->fs_devices, NULL);
-	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
 }
 
 const char * const btrfs_feature_set_names[3] = {
@@ -688,10 +687,6 @@ int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
 	int error = 0;
 	struct btrfs_device *dev;
 
-	error = btrfs_sysfs_add_device(fs_devices);
-	if (error)
-		return error;
-
 	list_for_each_entry(dev, &fs_devices->devices, dev_list) {
 		struct hd_struct *disk;
 		struct kobject *disk_kobj;
@@ -747,19 +742,13 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 
 	btrfs_set_fs_info_ptr(fs_info);
 
-	error = btrfs_sysfs_add_fsid(fs_devs, NULL);
-	if (error)
-		return error;
-
 	error = btrfs_kobj_add_device(fs_devs, NULL);
-	if (error) {
-		btrfs_sysfs_remove_fsid(fs_devs);
+	if (error)
 		return error;
-	}
 
 	error = sysfs_create_files(super_kobj, btrfs_attrs);
 	if (error) {
-		btrfs_sysfs_remove_fsid(fs_devs);
+		btrfs_kobj_rm_device(fs_devs, NULL);
 		return error;
 	}
 
-- 
2.0.0.153.g79dcccc

[PATCH 22/27] Btrfs: sysfs: add support to add parent for fsid

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

To support seed sysfs layout and represent seed fsid under
the sprout we need the facility to create fsid under the
specified parent.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index be5342f..51e2fae 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -729,8 +729,8 @@ int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
 
 	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);
+	error = kobject_init_and_add(&fs_devs->super_kobj,
+				&btrfs_ktype, parent, "%pU", fs_devs->fsid);
 	return error;
 }
 
-- 
2.0.0.153.g79dcccc

[PATCH 23/27] Btrfs: sysfs: don't fail seeding for the sake of sysfs kobject issue

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 549f978..58232bc 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2249,7 +2249,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 						root->fs_info->fsid);
 		if (kobject_rename(&root->fs_info->fs_devices->super_kobj,
 								fsid_buf))
-			goto error_trans;
+			pr_warn("BTRFS: sysfs: failed to create fsid for sprout\n");
 	}
 
 	root->fs_info->num_tolerated_disk_barrier_failures =
-- 
2.0.0.153.g79dcccc

[PATCH 24/27] Btrfs: free the stale device

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

When the btrfs on a device is overwritten with a new btrfs (mkfs),
the old btrfs instance in the kernel becomes stale. So with this
patch if kernel finds device is overwritten then delete the stale
fsid/uuid.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 58232bc..452abb3 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -446,6 +446,55 @@ static void pending_bios_fn(struct btrfs_work *work)
 	run_scheduled_bios(device);
 }
 
+
+void btrfs_free_stale_device(struct btrfs_device *cur_dev)
+{
+	int del = 0;
+	struct btrfs_fs_devices *fs_devs;
+	struct btrfs_device *dev;
+
+	list_for_each_entry(fs_devs, &fs_uuids, list) {
+		if (fs_devs->opened)
+			continue;
+		if (fs_devs->seeding)
+			continue;
+		list_for_each_entry(dev, &fs_devs->devices, dev_list) {
+			if (dev == cur_dev)
+				continue;
+
+			/*
+			 * Todo: This won't be enough. What if same device
+			 * comes back with new uuid and with its mapper path?
+			 * But for now, this does helps as mostly an admin will
+			 * use either mapper or non mapper path throughout.
+			 */
+
+			if (!strcmp(rcu_str_deref(dev->name),
+						rcu_str_deref(cur_dev->name))) {
+				del = 1;
+				break;
+			}
+		}
+		if (del) {
+			/* delete the stale */
+			if (fs_devs->num_devices == 1) {
+				btrfs_kobj_rm_device(fs_devs, dev);
+				btrfs_sysfs_remove_fsid(fs_devs);
+				list_del(&fs_devs->list);
+				free_fs_devices(fs_devs);
+			} else {
+				fs_devs->num_devices--;
+				btrfs_kobj_rm_device(fs_devs, dev);
+				list_del(&dev->dev_list);
+				rcu_string_free(dev->name);
+				kfree(dev);
+			}
+			break;
+		}
+	}
+	return;
+}
+
 /*
  * Add new device to list of registered devices
  *
@@ -561,6 +610,8 @@ static noinline int device_list_add(const char *path,
 	if (!fs_devices->opened)
 		device->generation = found_transid;
 
+	btrfs_free_stale_device(device);
+
 	*fs_devices_ret = fs_devices;
 
 	return ret;
-- 
2.0.0.153.g79dcccc

[PATCH 25/27] Btrfs: sysfs: add support to show replacing target in the sysfs

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

This patch will add support to show the replacing target in sysfs
during the process of replacement.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/dev-replace.c | 5 ++++-
 fs/btrfs/volumes.c     | 3 +++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 124b60f..f06390b 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -376,6 +376,10 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
 	WARN_ON(!tgt_device);
 	dev_replace->tgtdev = tgt_device;
 
+	ret = btrfs_kobj_add_device(tgt_device->fs_devices, tgt_device);
+	if (ret)
+		btrfs_error(root->fs_info, ret, "kobj add dev failed");
+
 	printk_in_rcu(KERN_INFO
 		      "BTRFS: dev_replace from %s (devid %llu) to %s started\n",
 		      src_device->missing ? "<missing disk>" :
@@ -593,7 +597,6 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 
 	/* replace the sysfs entry */
 	btrfs_kobj_rm_device(fs_info->fs_devices, src_device);
-	btrfs_kobj_add_device(fs_info->fs_devices, tgt_device);
 	btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 
 	/* write back the superblocks */
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 452abb3..f51f5ba 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1921,6 +1921,9 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 	mutex_lock(&uuid_mutex);
 	WARN_ON(!tgtdev);
 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
+
+	btrfs_kobj_rm_device(fs_info->fs_devices, tgtdev);
+
 	if (tgtdev->bdev) {
 		btrfs_scratch_superblock(tgtdev);
 		fs_info->fs_devices->open_devices--;
-- 
2.0.0.153.g79dcccc

[PATCH 26/27] Btrfs: sysfs: support seed devices in the sysfs layout

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

This adds an enhancement to show the seed fsid and devices.

The way sprouting handles fs_devices:
      clone seed fs_devices and add to the fs_uuids
      mem copy seed fs_devices and assign to fs_devices->seed (move dev_list)
      evacuate seed fs_devices contents to hold sprout fs devices contents

  So to be inline with this fs_devices changes during seeding,
  represent seed fsid under the sprout fsid, this is achieved
  by using the kobject_move()
  The end result will be,
    /sys/fs/btrfs/sprout-fsid/level-1-seed-fsid/(if)level-2-seed-fsid

eg: showing two levels of seeding.

find /sys/fs/btrfs/ -type d -name devices -exec ls {} \; -print

sde
/sys/fs/btrfs/8c2772d4-6951-43c3-89b6-3ab3c70a13f8/f7ef2904-ce89-4421-bfb0-49fd999e9a0b/devices
sdd
/sys/fs/btrfs/8c2772d4-6951-43c3-89b6-3ab3c70a13f8/f7ef2904-ce89-4421-bfb0-49fd999e9a0b/53ac3265-0c34-4afd-9453-cc0d1a07be64/devices
sdf
/sys/fs/btrfs/8c2772d4-6951-43c3-89b6-3ab3c70a13f8/devices

Signed-off-by: Anand Jain <anand.jain@oracle.com>

Btrfs: sysfs: add check if super kobject is already initialized

v2: when kobject is already created return EEXIST
v3: squash with patch 25

Signed-off-by: Anand Jain <anand.jain@oracle.com>

Btrfs: rename btrfs_kobj_add/rm_device

rename btrfs_kobj_add_device to btrfs_sysfs_add_device_link
rename btrfs_kobj_rm_device to btrfs_sysfs_rm_device_link

Signed-off-by: Anand Jain <anand.jain@oracle.com>

Btrfs: rearrange code for easy readability

no logical change

Signed-off-by: Anand Jain <anand.jain@oracle.com>

Btrfs: rename btrfs_sysfs_add_one to btrfs_sysfs_add_mounted

rename btrfs_sysfs_add_one to btrfs_sysfs_add_mounted

rename btrfs_sysfs_remove_one to btrfs_sysfs_remove_mounted

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/ctree.h       |   4 +-
 fs/btrfs/dev-replace.c |   4 +-
 fs/btrfs/disk-io.c     |  12 +--
 fs/btrfs/sysfs.c       | 207 ++++++++++++++++++++++++++++++++++---------------
 fs/btrfs/sysfs.h       |  14 ++--
 fs/btrfs/volumes.c     |  26 +++----
 6 files changed, 172 insertions(+), 95 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9493b91..5f25607 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3976,8 +3976,8 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 /* sysfs.c */
 int btrfs_init_sysfs(void);
 void btrfs_exit_sysfs(void);
-int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info);
-void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info);
+int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info);
+void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info);
 
 /* xattr.c */
 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size);
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index f06390b..61d183b 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -376,7 +376,7 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
 	WARN_ON(!tgt_device);
 	dev_replace->tgtdev = tgt_device;
 
-	ret = btrfs_kobj_add_device(tgt_device->fs_devices, tgt_device);
+	ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device, 0);
 	if (ret)
 		btrfs_error(root->fs_info, ret, "kobj add dev failed");
 
@@ -596,7 +596,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	mutex_unlock(&uuid_mutex);
 
 	/* replace the sysfs entry */
-	btrfs_kobj_rm_device(fs_info->fs_devices, src_device);
+	btrfs_sysfs_rm_device_link(fs_info->fs_devices, src_device, 0);
 	btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
 
 	/* write back the superblocks */
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4b7f3b8..4b19e41 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2785,19 +2785,19 @@ retry_root_backup:
 
 	btrfs_close_extra_devices(fs_info, fs_devices, 1);
 
-	ret = btrfs_sysfs_add_fsid(fs_devices, NULL);
-	if (ret) {
+	ret = btrfs_sysfs_add_fsid(fs_devices, NULL, 1);
+	if (ret && ret != -EEXIST) {
 		pr_err("BTRFS: failed to init sysfs fsid interface: %d\n", ret);
 		goto fail_block_groups;
 	}
 
-	ret = btrfs_sysfs_add_device(fs_devices);
+	ret = btrfs_sysfs_add_device(fs_devices, 1);
 	if (ret) {
 		pr_err("BTRFS: failed to init sysfs device interface: %d\n", ret);
 		goto fail_fsdev_sysfs;
 	}
 
-	ret = btrfs_sysfs_add_one(fs_info);
+	ret = btrfs_sysfs_add_mounted(fs_info);
 	if (ret) {
 		pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
 		goto fail_fsdev_sysfs;
@@ -3012,7 +3012,7 @@ fail_cleaner:
 	filemap_write_and_wait(fs_info->btree_inode->i_mapping);
 
 fail_sysfs:
-	btrfs_sysfs_remove_one(fs_info);
+	btrfs_sysfs_remove_mounted(fs_info);
 
 fail_fsdev_sysfs:
 	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
@@ -3693,7 +3693,7 @@ void close_ctree(struct btrfs_root *root)
 		       percpu_counter_sum(&fs_info->delalloc_bytes));
 	}
 
-	btrfs_sysfs_remove_one(fs_info);
+	btrfs_sysfs_remove_mounted(fs_info);
 	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
 
 	btrfs_free_fs_roots(fs_info);
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 51e2fae..e1b4f95 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -515,49 +515,6 @@ 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_devices *fs_devs)
-{
-	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_devs->super_kobj);
-	kobject_put(&fs_devs->super_kobj);
-	wait_for_completion(&fs_devs->kobj_unregister);
-}
-
-/* when fs_devs is NULL it will remove all fsid kobject */
-void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
-{
-	struct list_head *fs_uuids = btrfs_get_fs_uuids();
-
-	if (fs_devs) {
-		__btrfs_sysfs_remove_fsid(fs_devs);
-		return;
-	}
-
-	list_for_each_entry(fs_devs, fs_uuids, list) {
-		__btrfs_sysfs_remove_fsid(fs_devs);
-	}
-}
-
-void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
-{
-	btrfs_reset_fs_info_ptr(fs_info);
-
-	if (fs_info->space_info_kobj) {
-		sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
-		kobject_del(fs_info->space_info_kobj);
-		kobject_put(fs_info->space_info_kobj);
-	}
-	addrm_unknown_feature_attrs(fs_info, false);
-	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->fs_devices, NULL);
-}
-
 const char * const btrfs_feature_set_names[3] = {
 	[FEAT_COMPAT]	 = "compat",
 	[FEAT_COMPAT_RO] = "compat_ro",
@@ -633,10 +590,59 @@ static void init_feature_attrs(void)
 	}
 }
 
+static void __btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
+{
+	if (fs_devs->seed)
+		__btrfs_sysfs_remove_fsid(fs_devs->seed);
+
+	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;
+	}
+
+	if (fs_devs->super_kobj.state_initialized) {
+		kobject_del(&fs_devs->super_kobj);
+		kobject_put(&fs_devs->super_kobj);
+		wait_for_completion(&fs_devs->kobj_unregister);
+	}
+}
+
+/* when fs_devs is NULL it will remove all fsid kobject */
+void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
+{
+	struct list_head *fs_uuids = btrfs_get_fs_uuids();
+
+	if (fs_devs) {
+		__btrfs_sysfs_remove_fsid(fs_devs);
+		return;
+	}
+
+	list_for_each_entry(fs_devs, fs_uuids, list) {
+		__btrfs_sysfs_remove_fsid(fs_devs);
+	}
+}
+
+void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info)
+{
+	btrfs_reset_fs_info_ptr(fs_info);
+
+	if (fs_info->space_info_kobj) {
+		sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
+		kobject_del(fs_info->space_info_kobj);
+		kobject_put(fs_info->space_info_kobj);
+	}
+	addrm_unknown_feature_attrs(fs_info, false);
+	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_sysfs_rm_device_link(fs_info->fs_devices, NULL, 1);
+}
+
+
 /* when one_device is NULL, it removes all device links */
 
-int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
-		struct btrfs_device *one_device)
+int btrfs_sysfs_rm_device_link(struct btrfs_fs_devices *fs_devices,
+		struct btrfs_device *one_device, int follow_seed)
 {
 	struct hd_struct *disk;
 	struct kobject *disk_kobj;
@@ -666,27 +672,39 @@ int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
 						disk_kobj->name);
 	}
 
+	if (follow_seed && fs_devices->seed)
+		btrfs_sysfs_rm_device_link(fs_devices->seed, NULL, follow_seed);
+
 	return 0;
 }
 
-int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs)
+int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs, int follow_seed)
 {
-	if (!fs_devs->device_dir_kobj)
-		fs_devs->device_dir_kobj = kobject_create_and_add("devices",
-						&fs_devs->super_kobj);
 
-	if (!fs_devs->device_dir_kobj)
-		return -ENOMEM;
+	while (fs_devs) {
+		if (!fs_devs->device_dir_kobj)
+			fs_devs->device_dir_kobj = kobject_create_and_add(
+					"devices", &fs_devs->super_kobj);
+
+		if (!fs_devs->device_dir_kobj)
+			return -ENOMEM;
+
+		if (!follow_seed)
+			return 0;
+
+		fs_devs = fs_devs->seed;
+	}
 
 	return 0;
 }
 
-int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
-				struct btrfs_device *one_device)
+int btrfs_sysfs_add_device_link(struct btrfs_fs_devices *fs_devices,
+			struct btrfs_device *one_device, int follow_seed)
 {
 	int error = 0;
 	struct btrfs_device *dev;
 
+again:
 	list_for_each_entry(dev, &fs_devices->devices, dev_list) {
 		struct hd_struct *disk;
 		struct kobject *disk_kobj;
@@ -706,6 +724,11 @@ int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
 			break;
 	}
 
+	if (follow_seed && fs_devices->seed) {
+		fs_devices = fs_devices->seed;
+		goto again;
+	}
+
 	return error;
 }
 
@@ -723,18 +746,28 @@ u64 btrfs_debugfs_test;
  * And parent can be specified for seed device
  */
 int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
-				struct kobject *parent)
+				struct kobject *parent, int follow_seed)
 {
-	int error;
+	int error = 0;
 
-	init_completion(&fs_devs->kobj_unregister);
-	fs_devs->super_kobj.kset = btrfs_kset;
-	error = kobject_init_and_add(&fs_devs->super_kobj,
+	while (fs_devs) {
+		if (!fs_devs->super_kobj.state_initialized) {
+			init_completion(&fs_devs->kobj_unregister);
+			fs_devs->super_kobj.kset = btrfs_kset;
+			error = kobject_init_and_add(&fs_devs->super_kobj,
 				&btrfs_ktype, parent, "%pU", fs_devs->fsid);
+		} else {
+			error = -EEXIST;
+		}
+		if (!follow_seed)
+			return error;
+		parent = &fs_devs->super_kobj;
+		fs_devs = fs_devs->seed;
+	}
 	return error;
 }
 
-int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
+int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)
 {
 	int error;
 	struct btrfs_fs_devices *fs_devs = fs_info->fs_devices;
@@ -742,13 +775,13 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 
 	btrfs_set_fs_info_ptr(fs_info);
 
-	error = btrfs_kobj_add_device(fs_devs, NULL);
+	error = btrfs_sysfs_add_device_link(fs_devs, NULL, 1);
 	if (error)
 		return error;
 
 	error = sysfs_create_files(super_kobj, btrfs_attrs);
 	if (error) {
-		btrfs_kobj_rm_device(fs_devs, NULL);
+		btrfs_sysfs_rm_device_link(fs_devs, NULL, 0);
 		return error;
 	}
 
@@ -774,7 +807,7 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 
 	return 0;
 failure:
-	btrfs_sysfs_remove_one(fs_info);
+	btrfs_sysfs_remove_mounted(fs_info);
 	return error;
 }
 
@@ -816,3 +849,53 @@ void btrfs_exit_sysfs(void)
 	debugfs_remove_recursive(btrfs_debugfs_root_dentry);
 }
 
+void btrfs_sysfs_prepare_sprout_reset(void)
+{
+	/* close call would anyway cleanup */
+}
+
+void btrfs_sysfs_prepare_sprout(struct btrfs_fs_devices *fs_devices,
+				struct btrfs_fs_devices *seed_devices)
+{
+	char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];
+
+	/*
+	 * Sprouting has changed fsid of the mounted root,
+	 * so rename the fsid on the sysfs
+	 */
+	snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU", fs_devices->fsid);
+	if (kobject_rename(&fs_devices->super_kobj, fsid_buf)) {
+		pr_warn("Btrfs: sysfs: kobject move failed\n");
+		return;
+	}
+
+	/*
+	 * Create the seed fsid inside the sprout fsid
+	 * but should not create devices dir, instead
+	 * move it from the original fs_devices
+	 */
+	memset(&seed_devices->super_kobj, 0, sizeof(struct kobject));
+	seed_devices->device_dir_kobj = NULL;
+	memset(&seed_devices->kobj_unregister, 0,
+					sizeof(struct completion));
+	btrfs_sysfs_add_fsid(seed_devices, &fs_devices->super_kobj, 0);
+	if (kobject_move(fs_devices->device_dir_kobj,
+					&seed_devices->super_kobj))
+		pr_warn("Btrfs: sysfs: dev kobject move failed\n");
+
+	seed_devices->device_dir_kobj = fs_devices->device_dir_kobj;
+	fs_devices->device_dir_kobj = NULL;
+	btrfs_sysfs_add_device(fs_devices, 0);
+
+	/*
+	 * the kobj dev and devices attribute will be created
+	 * in the main function as part of the init_new_device
+	 * If this is a nested seed, that is if there is seed's
+	 * seed device then move that one level deep.
+	 */
+	if (seed_devices->seed) {
+		if (kobject_move(&seed_devices->seed->super_kobj,
+					&seed_devices->super_kobj))
+			pr_warn("Btrfs: sysfs: kobject move failed\n");
+	}
+}
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index 2b31f6f..b23e94c 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -70,12 +70,14 @@ char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags);
 extern const char * const btrfs_feature_set_names[3];
 extern struct kobj_type space_info_ktype;
 extern struct kobj_type btrfs_raid_ktype;
-int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
-		struct btrfs_device *one_device);
-int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devices,
-                struct btrfs_device *one_device);
+int btrfs_sysfs_add_device_link(struct btrfs_fs_devices *fs_devices,
+		struct btrfs_device *one_device, int follow_seed);
+int btrfs_sysfs_rm_device_link(struct btrfs_fs_devices *fs_devices,
+                struct btrfs_device *one_device, int follow_seed);
 int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
-				struct kobject *parent);
-int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs);
+				struct kobject *parent, int follow_seed);
+int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs, int follow_seed);
 void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs);
+void btrfs_sysfs_prepare_sprout(struct btrfs_fs_devices *fs_devices,
+				struct btrfs_fs_devices *seed_devices);
 #endif /* _BTRFS_SYSFS_H_ */
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f51f5ba..bf59224 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -27,6 +27,7 @@
 #include <linux/kthread.h>
 #include <linux/raid/pq.h>
 #include <linux/semaphore.h>
+#include <linux/kobject.h>
 #include <asm/div64.h>
 #include "ctree.h"
 #include "extent_map.h"
@@ -478,13 +479,13 @@ void btrfs_free_stale_device(struct btrfs_device *cur_dev)
 		if (del) {
 			/* delete the stale */
 			if (fs_devs->num_devices == 1) {
-				btrfs_kobj_rm_device(fs_devs, dev);
+				btrfs_sysfs_rm_device_link(fs_devs, dev, 0);
 				btrfs_sysfs_remove_fsid(fs_devs);
 				list_del(&fs_devs->list);
 				free_fs_devices(fs_devs);
 			} else {
 				fs_devs->num_devices--;
-				btrfs_kobj_rm_device(fs_devs, dev);
+				btrfs_sysfs_rm_device_link(fs_devs, dev, 0);
 				list_del(&dev->dev_list);
 				rcu_string_free(dev->name);
 				kfree(dev);
@@ -1752,7 +1753,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 	if (device->bdev) {
 		device->fs_devices->open_devices--;
 		/* remove sysfs entry */
-		btrfs_kobj_rm_device(root->fs_info->fs_devices, device);
+		btrfs_sysfs_rm_device_link(root->fs_info->fs_devices, device, 0);
 	}
 
 	call_rcu(&device->rcu, free_device);
@@ -1922,7 +1923,7 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 	WARN_ON(!tgtdev);
 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
 
-	btrfs_kobj_rm_device(fs_info->fs_devices, tgtdev);
+	btrfs_sysfs_rm_device_link(fs_info->fs_devices, tgtdev, 0);
 
 	if (tgtdev->bdev) {
 		btrfs_scratch_superblock(tgtdev);
@@ -2063,6 +2064,8 @@ static int btrfs_prepare_sprout(struct btrfs_root *root)
 		      ~BTRFS_SUPER_FLAG_SEEDING;
 	btrfs_set_super_flags(disk_super, super_flags);
 
+	btrfs_sysfs_prepare_sprout(fs_devices, seed_devices);
+
 	return 0;
 }
 
@@ -2260,7 +2263,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 				    tmp + 1);
 
 	/* add sysfs device entry */
-	btrfs_kobj_add_device(root->fs_info->fs_devices, device);
+	btrfs_sysfs_add_device_link(root->fs_info->fs_devices, device, 0);
 
 	/*
 	 * we've got more storage, clear any full flags on the space
@@ -2288,22 +2291,11 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	}
 
 	if (seeding_dev) {
-		char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];
-
 		ret = btrfs_finish_sprout(trans, root);
 		if (ret) {
 			btrfs_abort_transaction(trans, root, ret);
 			goto error_trans;
 		}
-
-		/* Sprouting would change fsid of the mounted root,
-		 * so rename the fsid on the sysfs
-		 */
-		snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU",
-						root->fs_info->fsid);
-		if (kobject_rename(&root->fs_info->fs_devices->super_kobj,
-								fsid_buf))
-			pr_warn("BTRFS: sysfs: failed to create fsid for sprout\n");
 	}
 
 	root->fs_info->num_tolerated_disk_barrier_failures =
@@ -2339,7 +2331,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 error_trans:
 	btrfs_end_transaction(trans, root);
 	rcu_string_free(device->name);
-	btrfs_kobj_rm_device(root->fs_info->fs_devices, device);
+	btrfs_sysfs_rm_device_link(root->fs_info->fs_devices, device, 0);
 	kfree(device);
 error:
 	blkdev_put(bdev, FMODE_EXCL);
-- 
2.0.0.153.g79dcccc

[PATCH 27/27] Btrfs: create sys/fs/btrfs/fsid when scanned instead of when mounted

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

This patch changes the life cycle of the exisiting sysfs kobjects
/sys/fs/btrfs/<fsid> and /sys/fs/btrfs/<fsid>/devices,
from that they are created and destroyed by mount and unmount event
respectively as of now, to created and destroyed by scanned-registered and
module-unload respectively.

So that information from the btrfs_fs_devices can be added.

This does not change life cycle of any attributes from the fs_info.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/disk-io.c | 3 ++-
 fs/btrfs/sysfs.c   | 7 ++++++-
 fs/btrfs/sysfs.h   | 3 ++-
 fs/btrfs/volumes.c | 6 +++++-
 4 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4b19e41..0155ce8 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3694,7 +3694,8 @@ void close_ctree(struct btrfs_root *root)
 	}
 
 	btrfs_sysfs_remove_mounted(fs_info);
-	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
+	if (fs_info->fs_devices->seed)
+		btrfs_sysfs_remove_fsid(fs_info->fs_devices->seed);
 
 	btrfs_free_fs_roots(fs_info);
 
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index e1b4f95..253e57e 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -845,6 +845,7 @@ int btrfs_init_sysfs(void)
 void btrfs_exit_sysfs(void)
 {
 	sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
+	btrfs_sysfs_remove_fsid(NULL);
 	kset_unregister(btrfs_kset);
 	debugfs_remove_recursive(btrfs_debugfs_root_dentry);
 }
@@ -855,7 +856,8 @@ void btrfs_sysfs_prepare_sprout_reset(void)
 }
 
 void btrfs_sysfs_prepare_sprout(struct btrfs_fs_devices *fs_devices,
-				struct btrfs_fs_devices *seed_devices)
+				struct btrfs_fs_devices *seed_devices,
+				struct btrfs_fs_devices *old_devices)
 {
 	char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];
 
@@ -898,4 +900,7 @@ void btrfs_sysfs_prepare_sprout(struct btrfs_fs_devices *fs_devices,
 					&seed_devices->super_kobj))
 			pr_warn("Btrfs: sysfs: kobject move failed\n");
 	}
+
+	btrfs_sysfs_add_fsid(old_devices, NULL, 0);
+	btrfs_sysfs_add_device(old_devices, 0);
 }
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index b23e94c..34b9864 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -79,5 +79,6 @@ int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs,
 int btrfs_sysfs_add_device(struct btrfs_fs_devices *fs_devs, int follow_seed);
 void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs);
 void btrfs_sysfs_prepare_sprout(struct btrfs_fs_devices *fs_devices,
-				struct btrfs_fs_devices *seed_devices);
+				struct btrfs_fs_devices *seed_devices,
+				struct btrfs_fs_devices *old_devices);
 #endif /* _BTRFS_SYSFS_H_ */
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index bf59224..dfb5062 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -523,6 +523,10 @@ static noinline int device_list_add(const char *path,
 		list_add(&fs_devices->list, &fs_uuids);
 
 		device = NULL;
+		if (btrfs_sysfs_add_fsid(fs_devices, NULL, 0))
+			printk(KERN_WARNING "Btrfs: sysfs add fsid failed\n");
+		if (btrfs_sysfs_add_device(fs_devices, 0))
+			printk(KERN_WARNING "Btrfs: sysfs add device failed\n");
 	} else {
 		device = __find_device(&fs_devices->devices, devid,
 				       disk_super->dev_item.uuid);
@@ -2064,7 +2068,7 @@ static int btrfs_prepare_sprout(struct btrfs_root *root)
 		      ~BTRFS_SUPER_FLAG_SEEDING;
 	btrfs_set_super_flags(disk_super, super_flags);
 
-	btrfs_sysfs_prepare_sprout(fs_devices, seed_devices);
+	btrfs_sysfs_prepare_sprout(fs_devices, seed_devices, old_devices);
 
 	return 0;
 }
-- 
2.0.0.153.g79dcccc

Re: [PATCH 00/27 V5] provide framework so that sysfs attributs from the fs_devices can be added

[Anand Jain]

Hi Dave,

  Can I check if this patch set is lined up for the integration branch ?
  Any comments ?

Thanks, Anand

On 03/20/2015 06:01 PM, Anand Jain wrote:
> This patch set 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.
>
> Just to note, patch 01 to 26 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. The test script test-btrfs-devmgt.sh can be found in the ml.
> Patch 27, makes two kobjects fsid and devices to be created during
> the device scan, however their attributes will continue to be created
> at the mount as original.
>
> v4->v5:
>    . add kobject_move patch 01/27
>    . commit corrections where necessary
>    . the individual patch version is not updated and I am maintaining
>      the patch set version as v5.
>
> v3->v4:
>    . reorders the patches
>    . accepts Dave comment
>    . needed stale device clean up, introduced patch..
> 	520353e Btrfs: free the stale device
>    . added cleanups to the patch to support seeding in the patch..
> 	e311d0a Btrfs: sysfs: support seed devices in the sysfs layout v3
>    . added support to show replacing target on the sysfs in the patch..
> 	e210d55 Btrfs: sysfs: add support to show replacing target in the sysfs
>
> v2->v3:
>    . added missing signed-off
>    . Dave comment
>    . there isn't v2 for individual patch, I marked individual patch v3
>      where necessary
> v1->v2:
>    . adds fresh set of patches from 12 to 24 to support seed fsids
>    on btrfs sysfs layout and the related frame work changes
>    . the patches 1 to 12 has no changes from the previous submit
>
>
> Anand Jain (27):
>    export symbol kobject_move()
>    Btrfs: sysfs: fix, btrfs_release_super_kobj() should to clean up the
>      kobject data
>    Btrfs: sysfs: fix, fs_info kobject_unregister has init_completion()
>      twice
>    Btrfs: sysfs: fix, undo sysfs device links
>    Btrfs: sysfs: fix, kobject pointer clean up needed after kobject
>      release
>    Btrfc: sysfs: fix, check if device_dir_kobj is init before destroy
>    Btrfs: sysfs: reorder the kobject creations
>    Btrfs: sysfs: rename __btrfs_sysfs_remove_one to
>      btrfs_sysfs_remove_fsid
>    Btrfs: sysfs: introduce function btrfs_sysfs_add_fsid() to create
>      sysfs fsid
>    Btrfs: sysfs: let default_attrs be separate from the kset
>    Btrfs: sysfs: separate device kobject and its attribute creation
>    Btrfs: sysfs: move super_kobj and device_dir_kobj from fs_info to
>      btrfs_fs_devices
>    Btrfs: introduce btrfs_get_fs_uuids to get fs_uuids
>    Btrfs: sysfs: add pointer to access fs_info from fs_devices
>    Btrfs: sysfs: provide framework to remove all fsid sysfs kobject
>    Btrfs: sysfs btrfs_kobj_add_device() pass fs_devices instead of
>      fs_info
>    Btrfs: sysfs btrfs_kobj_rm_device() pass fs_devices instead of fs_info
>    Btrfs: sysfs: make btrfs_sysfs_add_fsid() non static
>    Btrfs: sysfs: make btrfs_sysfs_add_device() non static
>    Btrfs: sysfs: btrfs_sysfs_remove_fsid() make it non static
>    Btrfs: sysfs: separate kobject and attribute creation
>    Btrfs: sysfs: add support to add parent for fsid
>    Btrfs: sysfs: don't fail seeding for the sake of sysfs kobject issue
>    Btrfs: free the stale device
>    Btrfs: sysfs: add support to show replacing target in the sysfs
>    Btrfs: sysfs: support seed devices in the sysfs layout
>    Btrfs: create sys/fs/btrfs/fsid when scanned instead of when mounted
>
>   fs/btrfs/ctree.h       |   7 +-
>   fs/btrfs/dev-replace.c |   7 +-
>   fs/btrfs/disk-io.c     |  26 ++++-
>   fs/btrfs/sysfs.c       | 266 +++++++++++++++++++++++++++++++++++++++----------
>   fs/btrfs/sysfs.h       |  15 ++-
>   fs/btrfs/volumes.c     |  99 +++++++++++++++---
>   fs/btrfs/volumes.h     |   9 ++
>   lib/kobject.c          |   1 +
>   8 files changed, 346 insertions(+), 84 deletions(-)
>

Re: [PATCH 00/27 V5] provide framework so that sysfs attributs from the fs_devices can be added

[David Sterba]

On Tue, Apr 07, 2015 at 04:08:52PM +0800, Anand Jain wrote:
>   Can I check if this patch set is lined up for the integration branch ?
>   Any comments ?

It's on my radar for 4.2.

Re: [PATCH 00/27 V5] provide framework so that sysfs attributs from the fs_devices can be added

[David Sterba]

On Tue, Apr 07, 2015 at 04:08:52PM +0800, Anand Jain wrote:
>   Can I check if this patch set is lined up for the integration branch ?
>   Any comments ?

I've noticed that the proposal to add an extra directory to the seeding
uuid hasn't been implemented.

http://article.gmane.org/gmane.comp.file-systems.btrfs/43095

  "I'm thinking about a representation of the possible relations between
  the devices. Seems that the seeding hierarchy for one filesystem is
  always linear, so it's ok to represent it by the filesystem UUID chain.

  /sys/fs/btrfs/UUID1/UUID2/UUID3

  What I still find unsatisfying is lack of any explicit naming attached
  to the UUIDs. As we can use lots of types of UUID, saying that "if it
  looks like an uuid if the main filesystem directory in sysfs, then it's
  the seeding filesystem" is not the best we can come up with.

  I don't have a final idea, but at least

  /sys/fs/btrfs/UUID1/seeding/UUID2/seeding/UUID3

  would look more friendly to the user and also more accssible to
  scripting. We coud possibly add other files/dirs to the inserted
  directory."

I still think that the plain UUID1/UUID2/... naming scheme is not
acceptable. Yes it is redundant in some way but also more descriptive.

Re: [PATCH 00/27 V5] provide framework so that sysfs attributs from the fs_devices can be added

[Anand Jain]

  some confusion, sorry about that. will get seed-fsid under seeding dir.
  (However seeding name was already used by an (upcoming) attribute
  (fs_devices->seeding), but now I am thinking seeding as a kobject dir
  is better, so will rename the attribute to something else.. like
  seeding_flag).

  thanks for the feedback.

Thanks, Anand


On 05/21/2015 12:40 AM, David Sterba wrote:
> On Tue, Apr 07, 2015 at 04:08:52PM +0800, Anand Jain wrote:
>>    Can I check if this patch set is lined up for the integration branch ?
>>    Any comments ?
>
> I've noticed that the proposal to add an extra directory to the seeding
> uuid hasn't been implemented.
>
> http://article.gmane.org/gmane.comp.file-systems.btrfs/43095
>
>    "I'm thinking about a representation of the possible relations between
>    the devices. Seems that the seeding hierarchy for one filesystem is
>    always linear, so it's ok to represent it by the filesystem UUID chain.
>
>    /sys/fs/btrfs/UUID1/UUID2/UUID3
>
>    What I still find unsatisfying is lack of any explicit naming attached
>    to the UUIDs. As we can use lots of types of UUID, saying that "if it
>    looks like an uuid if the main filesystem directory in sysfs, then it's
>    the seeding filesystem" is not the best we can come up with.
>
>    I don't have a final idea, but at least
>
>    /sys/fs/btrfs/UUID1/seeding/UUID2/seeding/UUID3
>
>    would look more friendly to the user and also more accssible to
>    scripting. We coud possibly add other files/dirs to the inserted
>    directory."
>
> I still think that the plain UUID1/UUID2/... naming scheme is not
> acceptable. Yes it is redundant in some way but also more descriptive.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: [PATCH 00/27 V5] provide framework so that sysfs attributs from the fs_devices can be added

[David Sterba]

On Thu, May 21, 2015 at 10:48:52PM +0800, Anand Jain wrote:
> 
>   some confusion, sorry about that. will get seed-fsid under seeding dir.

Great, thanks.

>   (However seeding name was already used by an (upcoming) attribute
>   (fs_devices->seeding), but now I am thinking seeding as a kobject dir
>   is better, so will rename the attribute to something else.. like
>   seeding_flag).

If 'seeding' is already reserved, then 'seed' for the directory would be
fine.

[PATCH v5.1 24/27] Btrfs: free the stale device

[Anand Jain]

When the btrfs on a device is overwritten with a new btrfs (mkfs),
the old btrfs instance in the kernel becomes stale. So with this
patch if kernel finds device is overwritten, then delete the stale
fsid/uuid.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
V5->V5.1: since this deals with only devices in unmounted state, don't
try to remove device link

 fs/btrfs/volumes.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 747241f..eb57331 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -445,6 +445,55 @@ static void pending_bios_fn(struct btrfs_work *work)
 	run_scheduled_bios(device);
 }
 
+void btrfs_free_stale_device(struct btrfs_device *cur_dev)
+{
+	int del = 0;
+	struct btrfs_fs_devices *fs_devs;
+	struct btrfs_device *dev;
+
+	if (!rcu_str_deref(cur_dev->name))
+		return;
+	list_for_each_entry(fs_devs, &fs_uuids, list) {
+		if (fs_devs->opened)
+			continue;
+		if (fs_devs->seeding)
+			continue;
+		list_for_each_entry(dev, &fs_devs->devices, dev_list) {
+			if (dev == cur_dev)
+				continue;
+
+			/*
+			 * Todo: This won't be enough. What if same device
+			 * comes back with new uuid and with its mapper path?
+			 * But for now, this does helps as mostly an admin will
+			 * use either mapper or non mapper path throughout.
+			 */
+			if (!rcu_str_deref(dev->name))
+				continue;
+			if (!strcmp(rcu_str_deref(dev->name),
+						rcu_str_deref(cur_dev->name))) {
+				del = 1;
+				break;
+			}
+		}
+		if (del) {
+			/* delete the stale */
+			if (fs_devs->num_devices == 1) {
+				btrfs_sysfs_remove_fsid(fs_devs);
+				list_del(&fs_devs->list);
+				free_fs_devices(fs_devs);
+			} else {
+				fs_devs->num_devices--;
+				list_del(&dev->dev_list);
+				rcu_string_free(dev->name);
+				kfree(dev);
+			}
+			break;
+		}
+	}
+	return;
+}
+
 /*
  * Add new device to list of registered devices
  *
@@ -560,6 +609,8 @@ static noinline int device_list_add(const char *path,
 	if (!fs_devices->opened)
 		device->generation = found_transid;
 
+	btrfs_free_stale_device(device);
+
 	*fs_devices_ret = fs_devices;
 
 	return ret;
-- 
2.0.0.257.g75cc6c6

Re: [PATCH v5.1 24/27] Btrfs: free the stale device

[David Sterba]

On Fri, May 22, 2015 at 11:33:48PM +0800, Anand Jain wrote:
> +void btrfs_free_stale_device(struct btrfs_device *cur_dev)
> +{
> +	int del = 0;
> +	struct btrfs_fs_devices *fs_devs;
> +	struct btrfs_device *dev;
> +
> +	if (!rcu_str_deref(cur_dev->name))
> +		return;

This looks like rcu-unprotected access, though there's an outer mutext
held in device_list_add that calls btrfs_free_stale_device. I'm not sure
that the device name should be used to do any sorts of checks at all.

> +	list_for_each_entry(fs_devs, &fs_uuids, list) {
> +		if (fs_devs->opened)
> +			continue;
> +		if (fs_devs->seeding)
> +			continue;
> +		list_for_each_entry(dev, &fs_devs->devices, dev_list) {
> +			if (dev == cur_dev)
> +				continue;
> +
> +			/*
> +			 * Todo: This won't be enough. What if same device
> +			 * comes back with new uuid and with its mapper path?
> +			 * But for now, this does helps as mostly an admin will
> +			 * use either mapper or non mapper path throughout.
> +			 */
> +			if (!rcu_str_deref(dev->name))
> +				continue;
> +			if (!strcmp(rcu_str_deref(dev->name),
> +						rcu_str_deref(cur_dev->name))) {
> +				del = 1;
> +				break;
> +			}
> +		}
> +		if (del) {
> +			/* delete the stale */
> +			if (fs_devs->num_devices == 1) {
> +				btrfs_sysfs_remove_fsid(fs_devs);
> +				list_del(&fs_devs->list);
> +				free_fs_devices(fs_devs);
> +			} else {
> +				fs_devs->num_devices--;
> +				list_del(&dev->dev_list);
> +				rcu_string_free(dev->name);
> +				kfree(dev);

Devices are normally freed by the rcu through free_device, this looks
suspicious to mix both approaches.

> +			}
> +			break;
> +		}
> +	}
> +	return;

Unnecessary return

> +}
> +
>  /*
>   * Add new device to list of registered devices
>   *
> @@ -560,6 +609,8 @@ static noinline int device_list_add(const char *path,
>  	if (!fs_devices->opened)
>  		device->generation = found_transid;
>  
> +	btrfs_free_stale_device(device);

It might be safe to do that in the end, but it should be explained
somewhere.

> +
>  	*fs_devices_ret = fs_devices;
>  
>  	return ret;

[PATCH v5.2 24/42] Btrfs: free the stale device

[Anand Jain]

When the btrfs on a device is overwritten with a new btrfs (mkfs),
the old btrfs instance in the kernel becomes stale. So with this
patch if kernel finds device is overwritten then delete the stale
fsid/uuid.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v5.1->v5.2: accepts David's review comments with thanks. esp.ly the
important rcu part
v5->v5.1: since this deals with only devices in unmounted state, don't
try to remove device link

 fs/btrfs/volumes.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e50005f..0a4df7a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -445,6 +445,62 @@ static void pending_bios_fn(struct btrfs_work *work)
 	run_scheduled_bios(device);
 }
 
+
+void btrfs_free_stale_device(struct btrfs_device *cur_dev)
+{
+	struct btrfs_fs_devices *fs_devs;
+	struct btrfs_device *dev;
+
+	if (!cur_dev->name)
+		return;
+
+	list_for_each_entry(fs_devs, &fs_uuids, list) {
+		int del = 1;
+
+		if (fs_devs->opened)
+			continue;
+		if (fs_devs->seeding)
+			continue;
+
+		list_for_each_entry(dev, &fs_devs->devices, dev_list) {
+
+			if (dev == cur_dev)
+				continue;
+			if (!dev->name)
+				continue;
+
+			/*
+			 * Todo: This won't be enough. What if the same device
+			 * comes back (with new uuid and) with its mapper path?
+			 * But for now, this does help as mostly an admin will
+			 * either use mapper or non mapper path throughout.
+			 */
+			rcu_read_lock();
+			del = strcmp(rcu_str_deref(dev->name),
+						rcu_str_deref(cur_dev->name));
+			rcu_read_unlock();
+			if (!del)
+				break;
+		}
+
+		if (!del) {
+			/* delete the stale device */
+			if (fs_devs->num_devices == 1) {
+				btrfs_sysfs_remove_fsid(fs_devs);
+				list_del(&fs_devs->list);
+				free_fs_devices(fs_devs);
+			} else {
+				fs_devs->num_devices--;
+				list_del(&dev->dev_list);
+				rcu_string_free(dev->name);
+				kfree(dev);
+			}
+			break;
+		}
+	}
+	return;
+}
+
 /*
  * Add new device to list of registered devices
  *
@@ -560,6 +616,12 @@ static noinline int device_list_add(const char *path,
 	if (!fs_devices->opened)
 		device->generation = found_transid;
 
+	/*
+	 * if there is new btrfs on an already registered device,
+	 * then remove the stale device entry.
+	 */
+	btrfs_free_stale_device(device);
+
 	*fs_devices_ret = fs_devices;
 
 	return ret;
-- 
2.4.1

Re: [PATCH v5.1 24/27] Btrfs: free the stale device

[Anand Jain]

Hi David, Thanks for comments, more below..

On 05/27/2015 07:34 PM, David Sterba wrote:
> On Fri, May 22, 2015 at 11:33:48PM +0800, Anand Jain wrote:
>> +void btrfs_free_stale_device(struct btrfs_device *cur_dev)
>> +{
>> +	int del = 0;
>> +	struct btrfs_fs_devices *fs_devs;
>> +	struct btrfs_device *dev;
>> +
>> +	if (!rcu_str_deref(cur_dev->name))
>> +		return;
>
> This looks like rcu-unprotected access, though there's an outer mutext
> held in device_list_add that calls btrfs_free_stale_device. I'm not sure
> that the device name should be used to do any sorts of checks at all.

  you are right.  I got this corrected in v5.2 just sent out.


>> +	list_for_each_entry(fs_devs, &fs_uuids, list) {
>> +		if (fs_devs->opened)
>> +			continue;
>> +		if (fs_devs->seeding)
>> +			continue;
>> +		list_for_each_entry(dev, &fs_devs->devices, dev_list) {
>> +			if (dev == cur_dev)
>> +				continue;
>> +
>> +			/*
>> +			 * Todo: This won't be enough. What if same device
>> +			 * comes back with new uuid and with its mapper path?
>> +			 * But for now, this does helps as mostly an admin will
>> +			 * use either mapper or non mapper path throughout.
>> +			 */
>> +			if (!rcu_str_deref(dev->name))
>> +				continue;
>> +			if (!strcmp(rcu_str_deref(dev->name),
>> +						rcu_str_deref(cur_dev->name))) {
>> +				del = 1;
>> +				break;
>> +			}
>> +		}
>> +		if (del) {
>> +			/* delete the stale */
>> +			if (fs_devs->num_devices == 1) {
>> +				btrfs_sysfs_remove_fsid(fs_devs);
>> +				list_del(&fs_devs->list);
>> +				free_fs_devices(fs_devs);
>> +			} else {
>> +				fs_devs->num_devices--;
>> +				list_del(&dev->dev_list);
>> +				rcu_string_free(dev->name);
>> +				kfree(dev);
>
> Devices are normally freed by the rcu through free_device, this looks
> suspicious to mix both approaches.

  yes its bit of mixed up, also in other parts as well, for eg:
  free_fs_devices(). Here I am following free_fs_devices,
  since free_stale will check on the devices that are unmounted.

>> +			}
>> +			break;
>> +		}
>> +	}
>> +	return;
>
> Unnecessary return

right.

>> +}
>> +
>>   /*
>>    * Add new device to list of registered devices
>>    *
>> @@ -560,6 +609,8 @@ static noinline int device_list_add(const char *path,
>>   	if (!fs_devices->opened)
>>   		device->generation = found_transid;
>>
>> +	btrfs_free_stale_device(device);
>
> It might be safe to do that in the end, but it should be explained
> somewhere.

Added, Thanks, Anand

>> +
>>   	*fs_devices_ret = fs_devices;
>>
>>   	return ret;
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

[PATCH v5.3 24/27] Btrfs: free the stale device

[Anand Jain]

From: Anand Jain <Anand.Jain@oracle.com>

When btrfs on a device is overwritten with a new btrfs (mkfs),
the old btrfs instance in the kernel becomes stale. So with this
patch, if kernel finds device is overwritten then delete the stale
fsid/uuid.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v5.2->v5.3: removed unnecessary return in retun void func
v5.1->v5.2: accepts David's review comments with thanks. esp.ly the
important rcu part
v5->v5.1: since this deals with only devices in unmounted state, don't
try to remove device link

 fs/btrfs/volumes.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e50005f..39d4d48 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -445,6 +445,61 @@ static void pending_bios_fn(struct btrfs_work *work)
 	run_scheduled_bios(device);
 }
 
+
+void btrfs_free_stale_device(struct btrfs_device *cur_dev)
+{
+	struct btrfs_fs_devices *fs_devs;
+	struct btrfs_device *dev;
+
+	if (!cur_dev->name)
+		return;
+
+	list_for_each_entry(fs_devs, &fs_uuids, list) {
+		int del = 1;
+
+		if (fs_devs->opened)
+			continue;
+		if (fs_devs->seeding)
+			continue;
+
+		list_for_each_entry(dev, &fs_devs->devices, dev_list) {
+
+			if (dev == cur_dev)
+				continue;
+			if (!dev->name)
+				continue;
+
+			/*
+			 * Todo: This won't be enough. What if the same device
+			 * comes back (with new uuid and) with its mapper path?
+			 * But for now, this does help as mostly an admin will
+			 * either use mapper or non mapper path throughout.
+			 */
+			rcu_read_lock();
+			del = strcmp(rcu_str_deref(dev->name),
+						rcu_str_deref(cur_dev->name));
+			rcu_read_unlock();
+			if (!del)
+				break;
+		}
+
+		if (!del) {
+			/* delete the stale device */
+			if (fs_devs->num_devices == 1) {
+				btrfs_sysfs_remove_fsid(fs_devs);
+				list_del(&fs_devs->list);
+				free_fs_devices(fs_devs);
+			} else {
+				fs_devs->num_devices--;
+				list_del(&dev->dev_list);
+				rcu_string_free(dev->name);
+				kfree(dev);
+			}
+			break;
+		}
+	}
+}
+
 /*
  * Add new device to list of registered devices
  *
@@ -560,6 +615,12 @@ static noinline int device_list_add(const char *path,
 	if (!fs_devices->opened)
 		device->generation = found_transid;
 
+	/*
+	 * if there is new btrfs on an already registered device,
+	 * then remove the stale device entry.
+	 */
+	btrfs_free_stale_device(device);
+
 	*fs_devices_ret = fs_devices;
 
 	return ret;
-- 
2.4.1