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qcow2: Fix error path in qcow2_snapshot_load_tmp 

If the bdrv_read() of the snapshot's L1 table fails, return the right
error code and make sure that the old L1 table is still loaded and we
don't break the BlockDriverState completely.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
This commit is contained in:
Kevin Wolf 2011-11-16 17:30:33 +01:00
parent 9a4767809f
commit e3f652b332
1 changed files with 23 additions and 13 deletions
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36
block/qcow2-snapshot.c
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@ -573,32 +573,42 @@ int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name)
{
int i, snapshot_index, l1_size2;
int i, snapshot_index;
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
uint64_t *new_l1_table;
int new_l1_bytes;
int ret;
assert(bs->read_only);
/* Search the snapshot */
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name);
if (snapshot_index < 0) {
return -ENOENT;
}
sn = &s->snapshots[snapshot_index];
/* Allocate and read in the snapshot's L1 table */
new_l1_bytes = s->l1_size * sizeof(uint64_t);
new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512));
ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes);
if (ret < 0) {
g_free(new_l1_table);
return ret;
}
/* Switch the L1 table */
g_free(s->l1_table);
s->l1_size = sn->l1_size;
l1_size2 = s->l1_size * sizeof(uint64_t);
if (s->l1_table != NULL) {
g_free(s->l1_table);
}
s->l1_table_offset = sn->l1_table_offset;
s->l1_table = g_malloc0(align_offset(l1_size2, 512));
if (bdrv_pread(bs->file, sn->l1_table_offset,
s->l1_table, l1_size2) != l1_size2) {
return -1;
}
s->l1_table = new_l1_table;
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
return 0;
}