On 6/25/21 5:54 PM, NeilBrown wrote:
> On Sat, 26 Jun 2021, Martin Steigerwald wrote:
>> And that Baloo needs an "invariant" for
>> a file. See comment #11 of that bug report:
>
> That is really hard to provide in general. Possibly the best approach
> is to use the statfs() systemcall to get the "f_fsid" field. This is
> 64bits. It is not supported uniformly well by all filesystems, but I
> think it is at least not worse than using the device number. For a lot
> of older filesystems it is just an encoding of the device number.
>
> For btrfs, xfs, ext4 it is much much better.
How about combining the UUID of the partition with the file path? An
example from one of the VMs on my workstation:
$ df .
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/vda1 25670972 12730276 11613648 53% /
$ lsblk -O | grep vda1
└─vda1 vda1 /dev/vda1 252:1 11.1G 24.5G ext4 12.1G 50% 1.0
/ 84cebea8-7e6f-4c2a-8a1b-8bc0c9744751 ae2151de
dos 0x83 Linux ae2151de-01
0x80 128 0 0 0
25G root disk brw-rw---- 0 512
0 512 512 1 mq-deadline 256 part 0 512B
2G 0 0B 0 vda block:virtio:pci
none 0
In other words, UUID 84cebea8-7e6f-4c2a-8a1b-8bc0c9744751 has been
associated with the block device under the filesystem that owns the
directory from which the 'df' command has been run.
Bart.
