From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Nck24-00019T-86 for qemu-devel@nongnu.org; Wed, 03 Feb 2010 13:32:56 -0500 Received: from [199.232.76.173] (port=32963 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Nck23-00018j-6g for qemu-devel@nongnu.org; Wed, 03 Feb 2010 13:32:55 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Nck1x-0000IS-On for qemu-devel@nongnu.org; Wed, 03 Feb 2010 13:32:54 -0500 Received: from mx1.redhat.com ([209.132.183.28]:21619) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Nck1x-0000IB-B3 for qemu-devel@nongnu.org; Wed, 03 Feb 2010 13:32:49 -0500 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o13IWltI014010 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 3 Feb 2010 13:32:47 -0500 From: Naphtali Sprei Date: Wed, 3 Feb 2010 20:32:27 +0200 Message-Id: <1265221948-12613-4-git-send-email-nsprei@redhat.com> In-Reply-To: <1265221948-12613-3-git-send-email-nsprei@redhat.com> References: <1265221948-12613-1-git-send-email-nsprei@redhat.com> <1265221948-12613-2-git-send-email-nsprei@redhat.com> <1265221948-12613-3-git-send-email-nsprei@redhat.com> Subject: [Qemu-devel] [PATCH 3/4] Block: readonly changes List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Naphtali Sprei 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 | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++------- block_int.h | 1 + 2 files changed, 57 insertions(+), 8 deletions(-) diff --git a/block.c b/block.c index 66564de..527b146 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 +579,34 @@ int bdrv_commit(BlockDriverState *bs) { BlockDriver *drv = bs->drv; int64_t i, total_sectors; - int n, j; + int n, j, ro; int ret = 0; unsigned char sector[512]; + 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; - if (!bs->backing_hd) { - return -ENOTSUP; + if (ro) { /* re-open as RW */ + bs_rw = bdrv_new(""); + ret = bdrv_open2(bs_rw, bs->backing_hd->filename, bs->backing_hd->open_flags | BDRV_O_RDWR, NULL); + if (ret < 0) { + bdrv_delete(bs_rw); + return -EACCES; + } + bdrv_close(bs->backing_hd); + qemu_free(bs->backing_hd); + bs->backing_hd = bs_rw; } total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; @@ -584,11 +614,13 @@ 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 +640,22 @@ int bdrv_commit(BlockDriverState *bs) */ if (bs->backing_hd) bdrv_flush(bs->backing_hd); + +ro_cleanup: + + if (ro) { /* re-open as RO */ + bs_ro = bdrv_new(""); + ret = bdrv_open2(bs_ro, bs->backing_hd->filename, bs->backing_hd->open_flags & ~BDRV_O_RDWR, NULL); + if (ret < 0) { + bdrv_delete(bs_ro); + return -EACCES; + } + bdrv_close(bs->backing_hd); + qemu_free(bs->backing_hd); + 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 */ -- 1.6.3.3