From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40573) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cEsaL-0005n8-MV for qemu-devel@nongnu.org; Thu, 08 Dec 2016 01:53:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cEsaK-0008KM-Rm for qemu-devel@nongnu.org; Thu, 08 Dec 2016 01:53:41 -0500 Date: Thu, 8 Dec 2016 14:53:32 +0800 From: Fam Zheng Message-ID: <20161208065332.GA2045@lemon> References: <1477928314-11184-1-git-send-email-famz@redhat.com> <1477928314-11184-2-git-send-email-famz@redhat.com> <29e8c31e-a05f-79b0-df81-ec84317496b9@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <29e8c31e-a05f-79b0-df81-ec84317496b9@redhat.com> Subject: Re: [Qemu-devel] [PATCH 01/14] osdep: Add qemu_lock_fd and qemu_unlock_fd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz Cc: qemu-devel@nongnu.org, "Daniel P. Berrange" , Kevin Wolf , qemu-block@nongnu.org, rjones@redhat.com On Fri, 12/02 01:30, Max Reitz wrote: > On 31.10.2016 16:38, Fam Zheng wrote: > > They are wrappers of POSIX fcntl "file private locking". > > > > Signed-off-by: Fam Zheng > > --- > > include/qemu/osdep.h | 2 ++ > > util/osdep.c | 29 +++++++++++++++++++++++++++++ > > 2 files changed, 31 insertions(+) > > > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > > index 0e3c330..f15e122 100644 > > --- a/include/qemu/osdep.h > > +++ b/include/qemu/osdep.h > > @@ -294,6 +294,8 @@ 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); > > > > #if defined(__HAIKU__) && defined(__i386__) > > #define FMT_pid "%ld" > > diff --git a/util/osdep.c b/util/osdep.c > > index 06fb1cf..b85a490 100644 > > --- a/util/osdep.c > > +++ b/util/osdep.c > > @@ -140,6 +140,35 @@ static int qemu_parse_fdset(const char *param) > > { > > return qemu_parse_fd(param); > > } > > + > > +static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type) > > +{ > > +#ifdef F_OFD_SETLK > > + int ret; > > + struct flock fl = { > > + .l_whence = SEEK_SET, > > + .l_start = start, > > + .l_len = len, > > + .l_type = fl_type, > > + }; > > + do { > > + ret = fcntl(fd, F_OFD_SETLK, &fl); > > + } while (ret == -1 && errno == EINTR); > > As I've asked in the last version: Can EINTR happen at all? My man page > tells me it's possible only with F(_OFD)_SETLKW. I think you are right, let's drop the condition. Fam > > Max > > > + return ret == -1 ? -errno : 0; > > +#else > > + return -ENOTSUP; > > +#endif > > +} > > + > > +int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive) > > +{ > > + return qemu_lock_fcntl(fd, start, len, exclusive ? F_WRLCK : F_RDLCK); > > +} > > + > > +int qemu_unlock_fd(int fd, int64_t start, int64_t len) > > +{ > > + return qemu_lock_fcntl(fd, start, len, F_UNLCK); > > +} > > #endif > > > > /* > > > >