From b1bf18223a8340cf5d52162d320badcfe07b905d Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 17 Feb 2025 20:16:39 +1030 Subject: [PATCH] btrfs: output an error message if btrfs failed to find the seed fsid [BUG] If btrfs failed to locate the seed device for whatever reason, mounting the sprouted device will fail without any meaning error message: # mkfs.btrfs -f /dev/test/scratch1 # btrfstune -S1 /dev/test/scratch1 # mount /dev/test/scratch1 /mnt/btrfs # btrfs dev add -f /dev/test/scratch2 /mnt/btrfs # umount /mnt/btrfs # btrfs dev scan -u # btrfs mount /dev/test/scratch2 /mnt/btrfs mount: /mnt/btrfs: fsconfig system call failed: No such file or directory. dmesg(1) may have more information after failed mount system call. # dmesg -t | tail -n6 BTRFS info (device dm-5): first mount of filesystem 64252ded-5953-4868-b962-cea48f7ac4ea BTRFS info (device dm-5): using crc32c (crc32c-generic) checksum algorithm BTRFS info (device dm-5): using free-space-tree BTRFS error (device dm-5): failed to read chunk tree: -2 BTRFS error (device dm-5): open_ctree failed: -2 [CAUSE] The failure to mount is pretty straight forward, just unable to find the seed device and its fsid, caused by `btrfs dev scan -u`. But the lack of any useful info is a problem. [FIX] Just add an extra error message in open_seed_devices() to indicate the error. Now the error message would look like this: BTRFS info (device dm-4): first mount of filesystem 7769223d-4db1-4e4c-ac29-0a96f53576ab BTRFS info (device dm-4): using crc32c (crc32c-generic) checksum algorithm BTRFS info (device dm-4): using free-space-tree BTRFS error (device dm-4): failed to find fsid e87c12e6-584b-4e98-8b88-962c33a619ff when attempting to open seed devices BTRFS error (device dm-4): failed to read chunk tree: -2 BTRFS error (device dm-4): open_ctree failed: -2 Link: https://github.com/kdave/btrfs-progs/issues/959 Reviewed-by: Anand Jain Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index a594f66daedf..f6ae76815e4b 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -7196,8 +7196,12 @@ static struct btrfs_fs_devices *open_seed_devices(struct btrfs_fs_info *fs_info, fs_devices = find_fsid(fsid, NULL); if (!fs_devices) { - if (!btrfs_test_opt(fs_info, DEGRADED)) + if (!btrfs_test_opt(fs_info, DEGRADED)) { + btrfs_err(fs_info, + "failed to find fsid %pU when attempting to open seed devices", + fsid); return ERR_PTR(-ENOENT); + } fs_devices = alloc_fs_devices(fsid); if (IS_ERR(fs_devices)) -- 2.50.1