RE: [PATCH 2/3] fd/locks: allow get the lock owner by F_OFD_GETLK

[David Laight]

From: Matthew Wilcox
> Sent: 20 June 2023 14:46
> 
> On Tue, Jun 20, 2023 at 06:39:07PM +0500, stsp wrote:
> > Though it will, for sure, represent the
> > task that _owns_ the lock.
> 
> No, it *DOESN'T*.  I can open a file, SCM_RIGHTS pass it to another task
> and then exit.  Now the only owner of that lock is the recipient ...
> who may not even have received the fd yet.

Do these locks persist across fork+exec?

What happens is a completely unrelated process opens /proc/<pid>/fd
while a lock is held and then the (nominally) lock-holding
process closes the fd (or exits).

While it might be a useful diagnostic to know the pid of the
process that acquired the lock it clearly has no relationship
with any process that currently has an fd[] table entry that
references the file.

	David

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