ZFS ghost files on 11.3-STABLE

[Miroslav Lachman]

Gareth de Vaux wrote on 2019/11/25 18:00:
> Hi all, I deleted a file (rm filter) by mistake instead of its backup 'filter~',
> however it seems a remnant of a much older version of the file (given by its
> date and content) is half hanging around?
> 
> $ ls -l filter
> ls: filter: No such file or directory
> 
> $ ls -l filter*
> -rw-r--r--  1 lordcow  lordcow  18179 Mar 28  2019 filter
> -rw-------  1 lordcow  lordcow  19092 Nov 20 23:36 filter~
> 
> $ stat filter
> stat: filter: stat: No such file or directory
> 
> $ stat filter*
> 1525321853 1911959 -rw-r--r-- 1 lordcow lordcow 4294967295 18179 "Mar 28 17:07:34 2019" "Mar 28 17:08:07 2019" "Mar 28 17:08:07 2019" "Mar 28 17:07:34 2019" 18432 24 0x800 filter
> 1525321853 833819 -rw------- 1 lordcow lordcow 4294967295 19092 "Aug 10 22:31:53 2016" "Nov 20 23:36:40 2019" "Nov 24 23:08:13 2019" "Nov 20 23:36:40 2019" 19456 24 0x800 filter~
> 
> $ cat filter
> cat: filter: No such file or directory
> 
> $ cat filter*
> (cats both files)
> 
> A zpool scrub returns no errors
> 
> I haven't tried to overwrite the file yet incase anyone wants some output.
> 
> 
> FreeBSD 11.3-STABLE #0 r353939
> 
> ZFS filesystem version: 5
> ZFS storage pool version: features support (5000)

Do you have snapshot of this dataset before you run the "rm filter"? 
What files are listed there?
It is possible you have some non printable (invisible) character in the 
filename. It can be trailing space, newline or something else so in fact 
it has different filename than the one of deleted file but it looks the 
same.

Miroslav Lachman