From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:42340) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SzsXC-0003HL-UY for qemu-devel@nongnu.org; Fri, 10 Aug 2012 12:58:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SzsXB-0002hP-OK for qemu-devel@nongnu.org; Fri, 10 Aug 2012 12:58:02 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:59020) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SzsXB-0002h7-HY for qemu-devel@nongnu.org; Fri, 10 Aug 2012 12:58:01 -0400 Received: from /spool/local by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 10 Aug 2012 10:57:58 -0600 Received: from d03relay01.boulder.ibm.com (d03relay01.boulder.ibm.com [9.17.195.226]) by d03dlp01.boulder.ibm.com (Postfix) with ESMTP id C92091FF0030 for ; Fri, 10 Aug 2012 16:56:31 +0000 (WET) Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay01.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q7AGuBWY181844 for ; Fri, 10 Aug 2012 10:56:11 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q7AGu6cS021795 for ; Fri, 10 Aug 2012 10:56:07 -0600 Message-ID: <50253D23.1090409@linux.vnet.ibm.com> Date: Fri, 10 Aug 2012 12:56:03 -0400 From: Corey Bryant MIME-Version: 1.0 References: <1344564649-6272-1-git-send-email-coreyb@linux.vnet.ibm.com> <1344564649-6272-8-git-send-email-coreyb@linux.vnet.ibm.com> <502537FF.8020701@redhat.com> In-Reply-To: <502537FF.8020701@redhat.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v8 7/7] block: Enable qemu_open/close to work with fd sets List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: aliguori@us.ibm.com, stefanha@linux.vnet.ibm.com, libvir-list@redhat.com, qemu-devel@nongnu.org, lcapitulino@redhat.com, pbonzini@redhat.com, eblake@redhat.com On 08/10/2012 12:34 PM, Kevin Wolf wrote: > Am 10.08.2012 04:10, schrieb Corey Bryant: >> When qemu_open is passed a filename of the "/dev/fdset/nnn" >> format (where nnn is the fdset ID), an fd with matching access >> mode flags will be searched for within the specified monitor >> fd set. If the fd is found, a dup of the fd will be returned >> from qemu_open. >> >> Each fd set has a reference count. The purpose of the reference >> count is to determine if an fd set contains file descriptors that >> have open dup() references that have not yet been closed. It is >> incremented on qemu_open and decremented on qemu_close. It is >> not until the refcount is zero that file desriptors in an fd set >> can be closed. If an fd set has dup() references open, then we >> must keep the other fds in the fd set open in case a reopen >> of the file occurs that requires an fd with a different access >> mode. >> >> Signed-off-by: Corey Bryant > >> @@ -78,6 +79,69 @@ int qemu_madvise(void *addr, size_t len, int advice) >> #endif >> } >> >> +/* >> + * Dups an fd and sets the flags >> + */ >> +static int qemu_dup(int fd, int flags) > > qemu_dup() is probably not a good name. We'll want to use it when we > need to get a wrapper around dup(). And I suspect that we will need it > for making bdrv_reopen() compatible with fdset refcounting. > Do you you have a suggestion for a name? >> +{ >> + int ret; >> + int serrno; >> + int dup_flags; >> + int setfl_flags; >> + >> + if (flags & O_CLOEXEC) { >> +#ifdef F_DUPFD_CLOEXEC >> + ret = fcntl(fd, F_DUPFD_CLOEXEC, 0); >> +#else >> + ret = dup(fd); >> + if (ret != -1) { >> + qemu_set_cloexec(ret); >> + } >> +#endif >> + } else { >> + ret = dup(fd); >> + } > > qemu_open() is supposed to add O_CLOEXEC by itself, so I think we should > execute the then branch unconditionally (or we would have to change the > qemu_dup() call below to add it - but the fact that O_CLOEXEC isn't even > necessarily defined doesn't help with that). Sure I can modify this to always add O_CLOEXEC. (I know you mentioned this before but I think I interpreted the comment as a question to others.) Do you also want me to modify qemu_open to always add O_CLOEXEC? -- Regards, Corey