Bug 214326

Summary:

unionfs+nullfs strange behaviour

Product:

Base System

Reporter:

root

Component:

kern

Assignee:

freebsd-fs (Nobody) <fs>

Status:

New ---

Severity:

Affects Only Me

CC:

agh, swills

Priority:

---

Keywords:

patch

Version:

10.3-RELEASE

Hardware:

Any

OS:

Any

Attachments:

Description	Flags
An experimental patch for unionfs internal cache(Nov 8, 2016)	none

Description root 2016-11-08 14:33:21 UTC

Created attachment 176786 [details]
An experimental patch for unionfs internal cache(Nov 8, 2016)

** This report may be related to, or duplicate of Bug #186360 **

With unionfs+nullfs, I saw a strange behaviour.

# mkdir mountfrom1 mountfrom2 mountto
# mkdir mountfrom1/a
# touch mountfrom2/b
# mount -t unionfs mountfrom1 mountto
# mount -t nullfs mountfrom2 mountto/a
# ls mountto/a/b
ls: mountto/a/b: No such file or directory
# ls mountto/a
b
# ls mountto/a/b
mountto/a/b

I digged into unionfs module, and found 'unionfs_lookup' is returning different vnode for same single object 'a', for mount and later "ls" command.
It is caused by a bug in unionfs's internal cache (I think), and I solved it with an attached patch.

Well, my patch omits a check for 'ISLASTCN', but I don't know why the check is needed.

Comment 1 Mark Linimon freebsd_committer

2023-12-28 12:07:25 UTC

Comment on attachment 176786 [details]
An experimental patch for unionfs internal cache(Nov 8, 2016)

^Triage: convert this to text/plain and set the Patch flag so that the
automation can see it.