Reopen: zfs diff shows original file as deleted when hard link to file is created and deleted between diff points #13283

[krisjwebb]

System information

Type	Linux
Distribution Name	Ubuntu
Distribution Version	22.04
Kernel Version	6.8.0-48-generic
Architecture	x86_64
OpenZFS Version	zfs-2.1.5-1ubuntu6~22.04.4

Describe the problem you're observing

Create a file in one directory (file1) and take a snapsot. Then hard link it to a file another directory (file2) and remove file2.
zfs diff reports the original file1 as deleted instead of file2.

Describe how to reproduce the problem

zfs create pool1/test-dataset
cd test-dataset
mkdir src dest
cd src
echo "this is a file" >file1
zfs snapshot pool1/test-dataset@snap1
cd ../dest
ln ../src/file2
rm file2
zfs diff pool1/test-dataset@snap1 pool1/test-dataset
M /mnt/pool1/test-dataset/dest
- /mnt/pool1/test-dataset/src/file1

Include any warning/errors/backtraces from the system logs