From 7af30ba6ebc4ddde6dddb3545343a3d22128a588 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 2 Jun 2026 14:56:49 +0930 Subject: [PATCH] btrfs: print a message when a missing device re-appears There is a bug report that fstrim crashed, and that crash is eventually pinned down to a missing device which re-appeared and screwed up callers that only checks BTRFS_DEV_STATE_MISSING, but not BTRFS_DEV_STATE_WRITEABLE nor device->bdev. A missing device re-appearing can be very tricky, as for now it will result in a device without WRITEABLE or MISSING flag, and still no bdev pointer. As the first step to enhance handling of such re-appearing missing devices, add a dmesg output when a missing device re-appeared. Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index f409f870a6bc..6eab4cc73ce4 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -963,6 +963,11 @@ static noinline struct btrfs_device *device_list_add(const char *path, devid, btrfs_dev_name(device), path, current->comm, task_pid_nr(current)); + } else { + btrfs_info(NULL, + "missing devid %llu re-appeared at %s scanned by %s (%d)", + devid, path, current->comm, + task_pid_nr(current)); } name = kstrdup(path, GFP_NOFS);