[PATCH 1/2] btrfs: device list could grow infinite

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

Reproducer 1:
modprobe -r btrfs; modprobe btrfs

while true ; do mkfs.btrfs -f /dev/sde > /dev/null 2>&1; done
CTLR-C
we keep stale FSIDs.

btrfs-devlist | egrep "/dev/sde" | wc -l
41

Reproducer 2:
mkfs.btrfs -d raid1 -m raid1 /dev/sdd /dev/sdf
mkfs.btrfs -f /dev/sdf
btrfs dev ready /dev/sdd
echo $?
0 <-- wrong

fix this at device_list_add() to check and delete if the newly added disk path
is already in the device list

Signed-off-by: Anand Jain <Anand.Jain@oracle.com>
---
 fs/btrfs/volumes.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b107ad8..91ba2cf 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -598,6 +598,40 @@ static void pending_bios_fn(struct btrfs_work *work)
 	run_scheduled_bios(device);
 }
 
+static void find_delete_duplicate_dev(struct btrfs_device *new_dev)
+{
+	struct btrfs_fs_devices *fs_devs;
+	struct btrfs_fs_devices *cur_fs_devs;
+	struct btrfs_device	*dev;
+
+	list_for_each_entry(fs_devs, &fs_uuids, list) {
+
+		if (new_dev->fs_devices == fs_devs || fs_devs->opened)
+			continue;
+
+		cur_fs_devs = fs_devs;
+		list_for_each_entry(dev, &cur_fs_devs->devices, dev_list) {
+
+			if (dev->name && !strcmp(new_dev->name->str,
+							dev->name->str)) {
+				if (cur_fs_devs->num_devices == 1) {
+					free_fs_devices(cur_fs_devs);
+				} else {
+					mutex_lock(&cur_fs_devs->device_list_mutex);
+					list_del_rcu(&dev->dev_list);
+					cur_fs_devs->num_devices--;
+					if (dev->missing)
+						cur_fs_devs->missing_devices--;
+					mutex_unlock(&cur_fs_devs->device_list_mutex);
+					rcu_string_free(dev->name);
+					kfree(dev);
+				}
+				return;
+			}
+		}
+	}
+}
+
 static noinline int device_list_add(const char *path,
 			   struct btrfs_super_block *disk_super,
 			   u64 devid, struct btrfs_fs_devices **fs_devices_ret)
@@ -708,6 +742,13 @@ static noinline int device_list_add(const char *path,
 		fs_devices->latest_devid = devid;
 		fs_devices->latest_trans = found_transid;
 	}
+
+	/*
+	 * if new fs is created on the same path we need to clean
+	 * the old one.
+	 */
+	find_delete_duplicate_dev(device);
+
 	*fs_devices_ret = fs_devices;
 	return 0;
 }
-- 
2.0.0.257.g75cc6c6