The nvme by-id symlink changes to the latest namespace when a new namespace gets
added, for example by connecting multiple NVMe/TCP host controllers via nvme
connect-all.
That is incorrect for persistent device links.
The persistent symbolic device link should continue to point to the same NVMe
namespace throughout the lifetime of the current boot.
Therefore the namespace id needs to be added to the link name.
This adds symlinks that allow accessing loopback block devices via stable
names that reference their backing block devices, make the unpredictable
naming of loopback devices less of an issue.
Example:
1. Create a loopback block device for a file $F
losetup --find $F
2. Reference the backing block device via its inode:
L="$(stat -c '/dev/loop/by-inode/%Hd:%Ld-%i' $F)"
fdisk $L
In the above the loop device name (which might be /dev/loop47 or any
other name) is not used at all.
When built without blkid, then udev-builtin-blkid is not built,
and the verifier warns about the unknown builtin:
60-persistent-storage.rules:114 Unknown builtin command: blkid --hint=session_offset=$env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}
60-persistent-storage.rules:117 Unknown builtin command: blkid --noraid
60-persistent-storage.rules:120 Unknown builtin command: blkid
60-persistent-storage.rules: udev rules check failed
Thomas Blume
Lennart Poettering
Dmitry V. Levin