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Re: [RFC][glibc PATCH] fcntl-linux.h: add new definitions and manual updates for open file description locks
- From: Jeff Layton <jlayton at redhat dot com>
- To: ams at gnu dot org
- Cc: libc-alpha at sourceware dot org, linux-fsdevel at vger dot kernel dot org, linux-kernel at vger dot kernel dot org, tytso at mit dot edu, dalias at libc dot org, mtk dot manpages at gmail dot com, samba-technical at lists dot samba dot org, nfs-ganesha-devel at lists dot sourceforge dot net, carlos at redhat dot com, metze at samba dot org, hch at infradead dot org, bharrosh at panasas dot com
- Date: Wed, 23 Apr 2014 11:28:43 -0400
- Subject: Re: [RFC][glibc PATCH] fcntl-linux.h: add new definitions and manual updates for open file description locks
- Authentication-results: sourceware.org; auth=none
- References: <1398253172-9221-1-git-send-email-jlayton at redhat dot com> <E1Wcyo3-0000Eg-UC at fencepost dot gnu dot org>
On Wed, 23 Apr 2014 11:09:51 -0400
ams@gnu.org (Alfred M. Szmidt) wrote:
> @@ -2890,7 +2894,7 @@ Get flags associated with the open file. @xref{File Status Flags}.
> Set flags associated with the open file. @xref{File Status Flags}.
>
> @item F_GETLK
> -Get a file lock. @xref{File Locks}.
> +Test a file lock. @xref{File Locks}.
>
> F_GETLK does get the (first) lock which blocks; it doesn't test for
> it. "Retrieves information about the first blocking lock ..." or
> something might be better than the original
>
> @@ -2898,6 +2902,18 @@ Set or clear a file lock. @xref{File Locks}.
> @item F_SETLKW
> Like @code{F_SETLK}, but wait for completion. @xref{File Locks}.
>
> +@item F_OFD_GETLK
> +Test a open file description lock. @xref{Open File Description Locks}.
> +Specific to Linux.
>
> Likewise. You infact write that it does get the lock information
> later in the document wrt. F_OFD_GETLK.
Sorry, I disagree here...GETLK is really a misnomer, IMO. TESTLK would
have been a better name.
It's a way to test whether a particular lock can be applied, and to
return information about a conflicting lock if it can't. If, for
instance there is no conflicting lock, then you don't "get" any lock
information back (l_type just gets reset to F_UNLCK).
--
Jeff Layton <jlayton@redhat.com>