From patchwork Thu Feb 4 22:04:28 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naphtali Sprei X-Patchwork-Id: 44557 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id CFE19B7D47 for ; Fri, 5 Feb 2010 09:11:00 +1100 (EST) Received: from localhost ([127.0.0.1]:39888 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nd9ub-0007fx-Nx for incoming@patchwork.ozlabs.org; Thu, 04 Feb 2010 17:10:57 -0500 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Nd9od-0006Oj-7P for qemu-devel@nongnu.org; Thu, 04 Feb 2010 17:04:47 -0500 Received: from [199.232.76.173] (port=46747 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nd9oc-0006O8-Dn for qemu-devel@nongnu.org; Thu, 04 Feb 2010 17:04:46 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Nd9oY-0000o2-3D for qemu-devel@nongnu.org; Thu, 04 Feb 2010 17:04:46 -0500 Received: from mx1.redhat.com ([209.132.183.28]:2143) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Nd9oX-0000nq-Gc for qemu-devel@nongnu.org; Thu, 04 Feb 2010 17:04:41 -0500 Received: from int-mx08.intmail.prod.int.phx2.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o14M4eSs009625 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 4 Feb 2010 17:04:40 -0500 Received: from localhost.localdomain (dhcp-0-60.tlv.redhat.com [10.35.0.60]) by int-mx08.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o14M4WGZ029322; Thu, 4 Feb 2010 17:04:39 -0500 From: Naphtali Sprei To: qemu-devel@nongnu.org Date: Fri, 5 Feb 2010 00:04:28 +0200 Message-Id: <1265321069-4105-4-git-send-email-nsprei@redhat.com> In-Reply-To: <1265321069-4105-3-git-send-email-nsprei@redhat.com> References: <1265321069-4105-1-git-send-email-nsprei@redhat.com> <1265321069-4105-2-git-send-email-nsprei@redhat.com> <1265321069-4105-3-git-send-email-nsprei@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.21 X-detected-operating-system: by monty-python.gnu.org: Genre and OS details not recognized. Cc: Naphtali Sprei Subject: [Qemu-devel] [PATCH v2 resend 3/4] Block: readonly changes X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Open backing file for read-only During commit upgrade to read-write and back at end to read-only Signed-off-by: Naphtali Sprei --- block.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++------- block_int.h | 1 + 2 files changed, 61 insertions(+), 8 deletions(-) diff --git a/block.c b/block.c index 66564de..4a9df91 100644 --- a/block.c +++ b/block.c @@ -451,7 +451,6 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags, if (flags & (BDRV_O_CACHE_WB|BDRV_O_NOCACHE)) bs->enable_write_cache = 1; - bs->read_only = (flags & BDRV_O_RDWR) == 0; if (!(flags & BDRV_O_FILE)) { open_flags = (flags & (BDRV_O_RDWR | BDRV_O_CACHE_MASK|BDRV_O_NATIVE_AIO)); if (bs->is_temporary) { /* snapshot should be writeable */ @@ -466,6 +465,7 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags, goto free_and_fail; } + bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR); if (drv->bdrv_getlength) { bs->total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; } @@ -482,13 +482,28 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags, filename, bs->backing_file); if (bs->backing_format[0] != '\0') back_drv = bdrv_find_format(bs->backing_format); + + open_flags &= ~BDRV_O_RDWR; /* clear RW, then restore from orig */ + if (bs->is_temporary) { + open_flags |= (flags & BDRV_O_RDWR); + } + ret = bdrv_open2(bs->backing_hd, backing_filename, open_flags, back_drv); - bs->backing_hd->read_only = (open_flags & BDRV_O_RDWR) == 0; + if (ret < 0) { + open_flags &= ~BDRV_O_RDWR; /* Fall-back to read-only for the backing file */ + ret = bdrv_open2(bs->backing_hd, backing_filename, open_flags, + back_drv); + } if (ret < 0) { bdrv_close(bs); return ret; } + if (!bs->is_temporary) { + bs->backing_hd->keep_read_only = bs->keep_read_only; /* base image inherits from "parent" and open read-only */ + } else { + bs->backing_hd->keep_read_only = !(flags & BDRV_O_RDWR); + } } if (!bdrv_key_required(bs)) { @@ -564,19 +579,38 @@ int bdrv_commit(BlockDriverState *bs) { BlockDriver *drv = bs->drv; int64_t i, total_sectors; - int n, j; + int n, j, ro, open_flags; int ret = 0; unsigned char sector[512]; + char filename[1024]; + BlockDriverState *bs_rw, *bs_ro; if (!drv) return -ENOMEDIUM; + + if (!bs->backing_hd) { + return -ENOTSUP; + } - if (bs->read_only) { + if (bs->backing_hd->keep_read_only) { return -EACCES; } + + ro = bs->backing_hd->read_only; + strncpy(filename, bs->backing_hd->filename, sizeof(filename)); + open_flags = bs->backing_hd->open_flags; - if (!bs->backing_hd) { - return -ENOTSUP; + if (ro) { /* re-open as RW */ + bdrv_close(bs->backing_hd); + qemu_free(bs->backing_hd); + + bs_rw = bdrv_new(""); + ret = bdrv_open2(bs_rw, filename, open_flags | BDRV_O_RDWR, NULL); + if (ret < 0) { + bdrv_delete(bs_rw); + return -EACCES; + } + bs->backing_hd = bs_rw; } total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; @@ -584,11 +618,13 @@ int bdrv_commit(BlockDriverState *bs) if (drv->bdrv_is_allocated(bs, i, 65536, &n)) { for(j = 0; j < n; j++) { if (bdrv_read(bs, i, sector, 1) != 0) { - return -EIO; + ret = -EIO; + goto ro_cleanup; } if (bdrv_write(bs->backing_hd, i, sector, 1) != 0) { - return -EIO; + ret = -EIO; + goto ro_cleanup; } i++; } @@ -608,6 +644,22 @@ int bdrv_commit(BlockDriverState *bs) */ if (bs->backing_hd) bdrv_flush(bs->backing_hd); + +ro_cleanup: + + if (ro) { /* re-open as RO */ + bdrv_close(bs->backing_hd); + qemu_free(bs->backing_hd); + bs_ro = bdrv_new(""); + ret = bdrv_open2(bs_ro, filename, open_flags & ~BDRV_O_RDWR, NULL); + if (ret < 0) { + bdrv_delete(bs_ro); + return -EACCES; + } + bs->backing_hd = bs_ro; + bs->backing_hd->keep_read_only = 0; + } + return ret; } diff --git a/block_int.h b/block_int.h index 9144d37..02fae5b 100644 --- a/block_int.h +++ b/block_int.h @@ -130,6 +130,7 @@ struct BlockDriverState { int64_t total_sectors; /* if we are reading a disk image, give its size in sectors */ int read_only; /* if true, the media is read only */ + int keep_read_only; /* if true, the media was requested to stay read only */ int open_flags; /* flags used to open the file */ int removable; /* if true, the media can be removed */ int locked; /* if true, the media cannot temporarily be ejected */