[v3,4/4] btrfs: sysfs, add devid/dev_state kobject and attribute
diff mbox series

Message ID 1576752093-30840-1-git-send-email-anand.jain@oracle.com
State New
Headers show
Series
  • Untitled series #219605
Related show

Commit Message

Anand Jain Dec. 19, 2019, 10:41 a.m. UTC
New sysfs attributes
  in_fs_metadata  missing  replace_target  writeable
are added under a new kobject
  UUID/devinfo/<devid>

These attributes reflects the state of the device from the kernel
fed by %btrfs_device::dev_state.
These attributes are born during mount and goes along with the dynamic
nature of the device add and delete, otherwise these attribute and kobject
gets deleted at unmount.

Sample output:
pwd
 /sys/fs/btrfs/6e1961f1-5918-4ecc-a22f-948897b409f7/devinfo/1/
ls
  in_fs_metadata  missing  replace_target  writeable
cat missing
  0

The output from these attributes are 0 or 1. 0 indicates unset and 1
indicates set.

As of now these attributes are readonly.

It is observed that the device delete thread and sysfs read thread will
not race because the delete thread calls sysfs kobject_put() which in turn
waits for existing sysfs read to complete.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v3:
  Use optional groupid devid in BTRFS_ATTR(), it was blank in v2.

V2:
  Make the devinfo attribute to carry one parameter, so now
  instead of dev_state attribute, we create in_fs_metadata,
  writeable, missing and replace_target attributes.

 fs/btrfs/sysfs.c   | 127 +++++++++++++++++++++++++++++++++++++++++++----------
 fs/btrfs/volumes.h |   2 +
 2 files changed, 106 insertions(+), 23 deletions(-)

Patch
diff mbox series

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 834f712ed60c..d414b98fb27f 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -978,29 +978,102 @@  int btrfs_sysfs_remove_devices_attr(struct btrfs_fs_devices *fs_devices,
 	if (!fs_devices->devices_kobj)
 		return -EINVAL;
 
-	if (one_device && one_device->bdev) {
-		disk = one_device->bdev->bd_part;
-		disk_kobj = &part_to_dev(disk)->kobj;
+	if (one_device) {
+		if (one_device->bdev) {
+			disk = one_device->bdev->bd_part;
+			disk_kobj = &part_to_dev(disk)->kobj;
+			sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
+		}
 
-		sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
-	}
+		kobject_del(&one_device->devid_kobj);
+		kobject_put(&one_device->devid_kobj);
 
-	if (one_device)
 		return 0;
+	}
 
-	list_for_each_entry(one_device,
-			&fs_devices->devices, dev_list) {
-		if (!one_device->bdev)
-			continue;
-		disk = one_device->bdev->bd_part;
-		disk_kobj = &part_to_dev(disk)->kobj;
+	list_for_each_entry(one_device, &fs_devices->devices, dev_list) {
 
-		sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
+		if (one_device->bdev) {
+			disk = one_device->bdev->bd_part;
+			disk_kobj = &part_to_dev(disk)->kobj;
+			sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
+		}
+		kobject_del(&one_device->devid_kobj);
+		kobject_put(&one_device->devid_kobj);
 	}
 
 	return 0;
 }
 
+static ssize_t btrfs_sysfs_writeable_show(struct kobject *kobj,
+					  struct kobj_attribute *a, char *buf)
+{
+	int val;
+	struct btrfs_device *device = container_of(kobj, struct btrfs_device,
+						   devid_kobj);
+
+	val = test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) ? 1 : 0;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+BTRFS_ATTR(devid, writeable, btrfs_sysfs_writeable_show);
+
+static ssize_t btrfs_sysfs_in_fs_metadata_show(struct kobject *kobj,
+					       struct kobj_attribute *a,
+					       char *buf)
+{
+	int val;
+	struct btrfs_device *device = container_of(kobj, struct btrfs_device,
+						   devid_kobj);
+
+	val = test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
+		       &device->dev_state) ? 1 : 0;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+BTRFS_ATTR(devid, in_fs_metadata, btrfs_sysfs_in_fs_metadata_show);
+
+static ssize_t btrfs_sysfs_missing_show(struct kobject *kobj,
+					struct kobj_attribute *a, char *buf)
+{
+	int val;
+	struct btrfs_device *device = container_of(kobj, struct btrfs_device,
+						   devid_kobj);
+
+	val = test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state) ? 1 : 0;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+BTRFS_ATTR(devid, missing, btrfs_sysfs_missing_show);
+
+static ssize_t btrfs_sysfs_replace_target_show(struct kobject *kobj,
+					       struct kobj_attribute *a,
+					       char *buf)
+{
+	int val;
+	struct btrfs_device *device = container_of(kobj, struct btrfs_device,
+						   devid_kobj);
+
+	val = test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state) ? 1 : 0;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+BTRFS_ATTR(devid, replace_target, btrfs_sysfs_replace_target_show);
+
+static struct attribute *devid_attrs[] = {
+	BTRFS_ATTR_PTR(devid, writeable),
+	BTRFS_ATTR_PTR(devid, in_fs_metadata),
+	BTRFS_ATTR_PTR(devid, missing),
+	BTRFS_ATTR_PTR(devid, replace_target),
+	NULL
+};
+ATTRIBUTE_GROUPS(devid);
+
+static struct kobj_type devid_ktype = {
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = devid_groups,
+};
+
 int btrfs_sysfs_add_devices_attr(struct btrfs_fs_devices *fs_devices,
 				 struct btrfs_device *one_device)
 {
@@ -1008,22 +1081,30 @@  int btrfs_sysfs_add_devices_attr(struct btrfs_fs_devices *fs_devices,
 	struct btrfs_device *dev;
 
 	list_for_each_entry(dev, &fs_devices->devices, dev_list) {
-		struct hd_struct *disk;
-		struct kobject *disk_kobj;
-
-		if (!dev->bdev)
-			continue;
 
 		if (one_device && one_device != dev)
 			continue;
 
-		disk = dev->bdev->bd_part;
-		disk_kobj = &part_to_dev(disk)->kobj;
+		if (dev->bdev) {
+			struct hd_struct *disk;
+			struct kobject *disk_kobj;
+
+			disk = dev->bdev->bd_part;
+			disk_kobj = &part_to_dev(disk)->kobj;
 
-		error = sysfs_create_link(fs_devices->devices_kobj,
-					  disk_kobj, disk_kobj->name);
-		if (error)
+			error = sysfs_create_link(fs_devices->devices_kobj,
+						  disk_kobj, disk_kobj->name);
+			if (error)
+				break;
+		}
+
+		error = kobject_init_and_add(&dev->devid_kobj, &devid_ktype,
+					     fs_devices->devinfo_kobj, "%llu",
+					     dev->devid);
+		if (error) {
+			kobject_put(&dev->devid_kobj);
 			break;
+		}
 	}
 
 	return error;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 38f2e8437b68..68021d1ee216 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -138,6 +138,8 @@  struct btrfs_device {
 	atomic_t dev_stat_values[BTRFS_DEV_STAT_VALUES_MAX];
 
 	struct extent_io_tree alloc_state;
+
+	struct kobject devid_kobj;
 };
 
 /*