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[Qemu-devel] [PATCH v2 3/9] qcow2: Update snapshot table information at
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH v2 3/9] qcow2: Update snapshot table information at once |
Date: |
Fri, 18 Nov 2011 19:28:59 +0100 |
Failing in the middle wouldn't help with the integrity of the image, so
doing everything in a single request seems better.
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow2-snapshot.c | 22 ++++++++++------------
1 files changed, 10 insertions(+), 12 deletions(-)
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index e91a286..1976df7 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -137,8 +137,10 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
QCowSnapshot *sn;
QCowSnapshotHeader h;
int i, name_size, id_str_size, snapshots_size;
- uint64_t data64;
- uint32_t data32;
+ struct {
+ uint32_t nb_snapshots;
+ uint64_t snapshots_offset;
+ } QEMU_PACKED header_data;
int64_t offset, snapshots_offset;
int ret;
@@ -200,24 +202,20 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
/*
* Update the header to point to the new snapshot table. This requires the
* new table and its refcounts to be stable on disk.
- *
- * FIXME This should be done with a single write
*/
ret = bdrv_flush(bs);
if (ret < 0) {
goto fail;
}
- data64 = cpu_to_be64(snapshots_offset);
- ret = bdrv_pwrite(bs->file, offsetof(QCowHeader, snapshots_offset),
- &data64, sizeof(data64));
- if (ret < 0) {
- goto fail;
- }
+ QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) !=
+ offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots));
+
+ header_data.nb_snapshots = cpu_to_be32(s->nb_snapshots);
+ header_data.snapshots_offset = cpu_to_be64(snapshots_offset);
- data32 = cpu_to_be32(s->nb_snapshots);
ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
- &data32, sizeof(data32));
+ &header_data, sizeof(header_data));
if (ret < 0) {
goto fail;
}
--
1.7.6.4
- [Qemu-devel] [PATCH v2 0/9] qcow2: Fix error paths for internal snapshots, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 4/9] qcow2: Cleanups and memleak fix in qcow2_snapshot_create, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 2/9] qcow2: Return real error code in qcow2_write_snapshots, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 8/9] qcow2: Fix order in qcow2_snapshot_delete, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 7/9] qcow2: Fix order of refcount updates in qcow2_snapshot_goto, Kevin Wolf, 2011/11/18
- [Qemu-devel] [PATCH v2 9/9] qcow2: Fix error path in qcow2_snapshot_load_tmp, Kevin Wolf, 2011/11/18