On 10/7/19 5:45 AM, Anand Jain wrote:
btrfs_free_extra_devids() reorgs fs_devices::latest_bdev
to point to the bdev with greatest device::generation number.
For a typical-missing device the generation number is zero so
fs_devices::latest_bdev will never point to it.
But if the missing device is due to alienating [1], then
device::generation is not-zero and if it is >= to rest of
device::generation in the list, then fs_devices::latest_bdev
ends up pointing to the missing device and reports the error
like this [2]
[1]
mkfs.btrfs -fq /dev/sdd && mount /dev/sdd /btrfs
mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
sleep 3 # avoid racing with udev's useless scans if needed
btrfs dev add -f /dev/sdb /btrfs
mount -o degraded /dev/sdc /btrfs1
[2]
mount: wrong fs type, bad option, bad superblock on /dev/sdc,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so.
kernel: BTRFS warning (device sdc): devid 1 uuid 072a0192-675b-4d5a-8640-a5cf2b2c704d is missing
kernel: BTRFS error (device sdc): failed to read devices
kernel: BTRFS error (device sdc): open_ctree failed
Fix the root of the issue, by checking if the the device is not
missing before it can be a contender for the fs_devices::latest_bdev
title.
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
This should be turned into an xfstests. You can add
Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Thanks,
Josef
