From patchwork Wed Apr 13 09:09:54 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 8819731 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 22875C0553 for ; Wed, 13 Apr 2016 09:11:21 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6A73F2025A for ; Wed, 13 Apr 2016 09:11:20 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 99117201FE for ; Wed, 13 Apr 2016 09:11:19 +0000 (UTC) Received: from localhost ([::1]:39503 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aqGpS-0007nu-RU for patchwork-qemu-devel@patchwork.kernel.org; Wed, 13 Apr 2016 05:11:18 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48345) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aqGog-0006bM-9T for qemu-devel@nongnu.org; Wed, 13 Apr 2016 05:10:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aqGof-0001oL-1l for qemu-devel@nongnu.org; Wed, 13 Apr 2016 05:10:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54961) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aqGoX-0001mV-HP; Wed, 13 Apr 2016 05:10:21 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 44FB481106; Wed, 13 Apr 2016 09:10:21 +0000 (UTC) Received: from lemon.nay.redhat.com (dhcp-14-170.nay.redhat.com [10.66.14.170]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u3D9A07a003879; Wed, 13 Apr 2016 05:10:18 -0400 From: Fam Zheng To: qemu-devel@nongnu.org Date: Wed, 13 Apr 2016 17:09:54 +0800 Message-Id: <1460538604-12132-6-git-send-email-famz@redhat.com> In-Reply-To: <1460538604-12132-1-git-send-email-famz@redhat.com> References: <1460538604-12132-1-git-send-email-famz@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-block@nongnu.org, Jeff Cody , Markus Armbruster , Max Reitz , den@openvz.org, pbonzini@redhat.com, John Snow Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Because virtlockd in libvirt already uses the fcntl lock on the image file, we have to workaround this by locking a digest-mapped temporary file. Signed-off-by: Fam Zheng --- block/raw-posix.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) diff --git a/block/raw-posix.c b/block/raw-posix.c index 906d5c9..277f20d 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -35,6 +35,7 @@ #include "raw-aio.h" #include "qapi/util.h" #include "qapi/qmp/qstring.h" +#include "glib.h" #if defined(__APPLE__) && (__MACH__) #include @@ -149,6 +150,9 @@ typedef struct BDRVRawState { bool discard_zeroes:1; bool has_fallocate; bool needs_alignment; + bool image_locked; + int lock_file_fd; + char *lock_file_name; } BDRVRawState; typedef struct BDRVRawReopenState { @@ -397,6 +401,87 @@ static void raw_attach_aio_context(BlockDriverState *bs, #endif } +static int raw_do_lockf(int fd, BdrvLockfCmd cmd) +{ + int ret; + struct flock fl = (struct flock) { + .l_start = 0, + .l_whence = SEEK_SET, + .l_len = 0, + }; + switch (cmd) { + case BDRV_LOCKF_RWLOCK: + fl.l_type = F_WRLCK; + break; + case BDRV_LOCKF_ROLOCK: + fl.l_type = F_RDLCK; + break; + case BDRV_LOCKF_UNLOCK: + fl.l_type = F_UNLCK; + break; + default: + abort(); + } + ret = fcntl(fd, F_SETLK, &fl); + return ret == -1 ? -errno : 0; +} + +static char *raw_get_lock_file_name(BlockDriverState *bs) +{ + GChecksum *cksm; + const char *digest; + char *lock_file = NULL; + char *fullpath = g_malloc(PATH_MAX); + + if (!realpath(bs->filename, fullpath)) { + pstrcpy(fullpath, PATH_MAX, bs->filename); + } + cksm = g_checksum_new(G_CHECKSUM_SHA1); + g_checksum_update(cksm, (const guchar *)fullpath, strlen(fullpath)); + g_free(fullpath); + digest = g_checksum_get_string(cksm); + if (digest) { + lock_file = g_strdup_printf("/var/tmp/.qemu-%s.lock", digest); + } + g_checksum_free(cksm); + return lock_file; +} + +static int raw_lockf(BlockDriverState *bs, BdrvLockfCmd cmd, Error **errp) +{ + + BDRVRawState *s = bs->opaque; + int ret; + + if ((cmd == BDRV_LOCKF_UNLOCK) == (!s->image_locked)) { + return 0; + } + if (s->lock_file_fd == -1) { + /* Create and open the lock file if necessary. */ + + assert(cmd != BDRV_LOCKF_UNLOCK); + + s->lock_file_name = raw_get_lock_file_name(bs); + + s->lock_file_fd = qemu_open(s->lock_file_name, O_RDWR | O_CREAT, 0644); + if (s->lock_file_fd == -1) { + error_setg_errno(errp, errno, "Failed to open file"); + ret = -EIO; + goto out; + } + } + + ret = raw_do_lockf(s->lock_file_fd, cmd); + if (ret) { + error_setg_errno(errp, errno, + "Failed to lock file: %s", s->lock_file_name); + } else { + s->image_locked = cmd != BDRV_LOCKF_UNLOCK; + } +out: + return ret; +} + #ifdef CONFIG_LINUX_AIO static int raw_set_aio(void **aio_ctx, int *use_aio, int bdrv_flags) { @@ -585,6 +670,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags, int ret; s->type = FTYPE_FILE; + s->lock_file_fd = -1; ret = raw_open_common(bs, options, flags, 0, &local_err); if (local_err) { error_propagate(errp, local_err); @@ -1393,6 +1479,15 @@ static void raw_close(BlockDriverState *bs) raw_detach_aio_context(bs); + if (s->lock_file_fd != -1) { + qemu_close(s->lock_file_fd); + s->lock_file_fd = -1; + } + if (s->lock_file_name) { + unlink(s->lock_file_name); + g_free(s->lock_file_name); + s->lock_file_name = NULL; + } #ifdef CONFIG_LINUX_AIO if (s->use_aio) { laio_cleanup(s->aio_ctx); @@ -1960,6 +2055,8 @@ BlockDriver bdrv_file = { .bdrv_detach_aio_context = raw_detach_aio_context, .bdrv_attach_aio_context = raw_attach_aio_context, + .bdrv_lockf = raw_lockf, + .create_opts = &raw_create_opts, };