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[Qemu-devel] [PATCH 15/41] qcow2: Rework qcow2_snapshot_create error han
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 15/41] qcow2: Rework qcow2_snapshot_create error handling |
Date: |
Mon, 5 Dec 2011 15:20:52 +0100 |
Increase refcounts only after allocating a new L1 table has succeeded in
order to make leaks less likely. If writing the snapshot table fails,
revert in-memory state to be consistent with that on disk.
While at it, make it return the real error codes instead of -1.
Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
---
block/qcow2-snapshot.c | 55 +++++++++++++++++++++++++++++++++++------------
1 files changed, 41 insertions(+), 14 deletions(-)
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 53d9233..a8add9c 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -277,7 +277,9 @@ static int find_snapshot_by_id_or_name(BlockDriverState
*bs, const char *name)
int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
{
BDRVQcowState *s = bs->opaque;
- QCowSnapshot *snapshots1, sn1, *sn = &sn1;
+ QCowSnapshot *new_snapshot_list = NULL;
+ QCowSnapshot *old_snapshot_list = NULL;
+ QCowSnapshot sn1, *sn = &sn1;
int i, ret;
uint64_t *l1_table = NULL;
int64_t l1_table_offset;
@@ -303,16 +305,12 @@ int qcow2_snapshot_create(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info)
sn->date_nsec = sn_info->date_nsec;
sn->vm_clock_nsec = sn_info->vm_clock_nsec;
- ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size,
1);
- if (ret < 0)
- goto fail;
-
/* Allocate the L1 table of the snapshot and copy the current one there. */
l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
if (l1_table_offset < 0) {
+ ret = l1_table_offset;
goto fail;
}
- bdrv_flush(bs->file);
sn->l1_table_offset = l1_table_offset;
sn->l1_size = s->l1_size;
@@ -321,22 +319,50 @@ int qcow2_snapshot_create(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info)
for(i = 0; i < s->l1_size; i++) {
l1_table[i] = cpu_to_be64(s->l1_table[i]);
}
- if (bdrv_pwrite_sync(bs->file, sn->l1_table_offset,
- l1_table, s->l1_size * sizeof(uint64_t)) < 0)
+
+ ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
+ s->l1_size * sizeof(uint64_t));
+ if (ret < 0) {
goto fail;
+ }
+
g_free(l1_table);
l1_table = NULL;
- snapshots1 = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
+ /*
+ * Increase the refcounts of all clusters and make sure everything is
+ * stable on disk before updating the snapshot table to contain a pointer
+ * to the new L1 table.
+ */
+ ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size,
1);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = bdrv_flush(bs);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* Append the new snapshot to the snapshot list */
+ new_snapshot_list = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
if (s->snapshots) {
- memcpy(snapshots1, s->snapshots, s->nb_snapshots *
sizeof(QCowSnapshot));
- g_free(s->snapshots);
+ memcpy(new_snapshot_list, s->snapshots,
+ s->nb_snapshots * sizeof(QCowSnapshot));
+ old_snapshot_list = s->snapshots;
}
- s->snapshots = snapshots1;
+ s->snapshots = new_snapshot_list;
s->snapshots[s->nb_snapshots++] = *sn;
- if (qcow2_write_snapshots(bs) < 0)
+ ret = qcow2_write_snapshots(bs);
+ if (ret < 0) {
+ g_free(s->snapshots);
+ s->snapshots = old_snapshot_list;
goto fail;
+ }
+
+ g_free(old_snapshot_list);
+
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};
@@ -349,7 +375,8 @@ fail:
g_free(sn->id_str);
g_free(sn->name);
g_free(l1_table);
- return -1;
+
+ return ret;
}
/* copy the snapshot 'snapshot_name' into the current disk image */
--
1.7.6.4
- [Qemu-devel] [PULL 00/41] Block patches, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 01/41] qcow2: Unlock during COW, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 08/41] block: add I/O throttling algorithm, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 07/41] CoQueue: introduce qemu_co_queue_wait_insert_head, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 05/41] block: Use bdrv functions to replace file operation in cow.c, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 04/41] xen_disk: remove dead code, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 06/41] block: add the blockio limits command line support, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 02/41] qcow2: avoid reentrant bdrv_read() in copy_sectors(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 03/41] qed: adjust the way to get nb_sectors, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 13/41] qcow2: Update snapshot table information at once, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 15/41] qcow2: Rework qcow2_snapshot_create error handling,
Kevin Wolf <=
- [Qemu-devel] [PATCH 10/41] block: Add coroutine_fn marker to coroutine functions, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 09/41] hmp/qmp: add block_set_io_throttle, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 12/41] qcow2: Return real error code in qcow2_write_snapshots, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 11/41] qcow2: Return real error code in qcow2_read_snapshots, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 14/41] qcow2: Cleanups and memleak fix in qcow2_snapshot_create, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 16/41] qcow2: Return real error in qcow2_snapshot_goto, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 19/41] qcow2: Fix error path in qcow2_snapshot_load_tmp, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 18/41] qcow2: Fix order in qcow2_snapshot_delete, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 17/41] qcow2: Fix order of refcount updates in qcow2_snapshot_goto, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 22/41] qed: convert to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05