On 10/7/19 5:45 AM, Anand Jain wrote:
When the old device has new fsid through btrfs device add -f <dev> our fs_devices list has an alien device in one of the fs_devices. By having an alien device in fs_devices, we have two issues so far 1. missing device is not shows as missing in the userland Which is due to cracks in the function btrfs_open_one_device() and hardened by patch btrfs: delete identified alien device in open_fs_devices 2. mount of a degraded fs_devices fails Which is due to cracks in the function btrfs_free_extra_devids() and hardened by patch btrfs: include non-missing as a qualifier for the latest_bdev Now the reason for both of this issue is that there is an alien (does not contain the intended fsid) device in the fs_devices. We know a device can be scanned/added through btrfs-control::BTRFS_IOC_SCAN_DEV|BTRFS_IOC_DEVICES_READY or by ioctl::BTRFS_IOC_ADD_DEV And device coming through btrfs-control is checked against the all other devices in btrfs kernel but not coming through BTRFS_IOC_ADD_DEV. This patch checks if the device add is alienating any other scanned device and deletes it. In fact, this patch fixes both the issues 1 and 2 (above) by eliminating the source of the issue, but still they have their own patch as well because its the right way to harden the functions and fill the cracks. Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
I agree, but mostly because btrfs_scan_one_device(), which is what gets called by the control thingy, does this in the case that it adds a device. This patch makes add dev consistent with the normal scanning stuff, so I'm ok with it.
Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Thanks, Josef
