From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37627) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d3MVZ-0000qp-4I for qemu-devel@nongnu.org; Wed, 26 Apr 2017 08:57:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d3MVY-0007Di-F8 for qemu-devel@nongnu.org; Wed, 26 Apr 2017 08:57:25 -0400 Date: Wed, 26 Apr 2017 14:57:14 +0200 From: Kevin Wolf Message-ID: <20170426125714.GG4538@noname.str.redhat.com> References: <20170426033413.17192-1-famz@redhat.com> <20170426033413.17192-20-famz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170426033413.17192-20-famz@redhat.com> Subject: Re: [Qemu-devel] [PATCH v15 19/21] osdep: Add qemu_lock_fd and qemu_unlock_fd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: qemu-devel@nongnu.org, eblake@redhat.com, Max Reitz , qemu-block@nongnu.org Am 26.04.2017 um 05:34 hat Fam Zheng geschrieben: > They are wrappers of POSIX fcntl "file private locking", with a > convenient "try lock" wrapper implemented with F_OFD_GETLK. > > Signed-off-by: Fam Zheng > Reviewed-by: Max Reitz > --- > include/qemu/osdep.h | 3 +++ > util/osdep.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 51 insertions(+) > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index 122ff06..1c9f5e2 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -341,6 +341,9 @@ int qemu_close(int fd); > #ifndef _WIN32 > int qemu_dup(int fd); > #endif > +int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive); > +int qemu_unlock_fd(int fd, int64_t start, int64_t len); > +int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive); For the record: On IRC, I proposed adding something like the following: #ifndef F_OFD_SETLK #define F_OFD_SETLK F_SETLK #define F_OFD_GETLK F_GETLK #endif F_OFD_* are still relatively new and e.g. RHEL 7 doesn't support it yet. Using process-based locks is suboptimal because we can easily lose them earlier than we want, but it's still better than nothing and covers the common simple cases. Kevin