Ubuntu jail file count out of sync in directory with millions of files

[Forrest Gump]

I've got an Ubuntu Jail on FreeNAS 9.3 (and had one with 9.2.x as well), and I'm seeing a very strange behavior with a directory that has millions of files in it (and growing). The directory in question is shared via the built-in "Add Storage" feature.

root@ubuntu:/mnt/test# ls | wc -l
5432395
root@ubuntu:/mnt/test# ls | wc -l
4587545
root@ubuntu:/mnt/test# ls | wc -l
404516
root@ubuntu:/mnt/test# ls | wc -l
3895953

The first attempt is an accurate count of the number of files in the directory. However, the three subsequent attempts are not accurate. Eventually the count will get back to normal again, but also likely cycle as demonstrated above.

Notes:

• Yes, I realize that millions of files in a single directory is a bad idea. But I expect consistent behavior.
• It's not immediately obvious when the file count is below what it should be, which files are missing. Oldest files? Newest files? Something nondeterministic?

When doing the same test outside of a jail, or even in a standard FreeBSD jail, the file count is accurate (Currently ~5.4Million files and growing)

Thoughts?

 

[dlavigne]

Wonders if xargs needs to be involved giving the number of files being piped into wc....

 

[Forrest Gump]

Wonders if xargs needs to be involved given the number of files being piped into wc....

No difference. Given that there's no wildcard expansion happening, I wouldn't expect any difference or limit. ls | wc -l is the simplest example. find behaves the same way, as does the python:
files = os.listdir('.')
print('Files in directory: %s' % len(files))

 

[Forrest Gump]

The bug is reproducible, and I've filed: https://bugs.freenas.org/issues/7186