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@xxxxxxxxxx>
---
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
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