From e3f652b33228e16e117a93fb919c4e1e4753f5a5 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 16 Nov 2011 17:30:33 +0100 Subject: [PATCH] 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 Reviewed-by: Stefan Hajnoczi --- block/qcow2-snapshot.c | 36 +++++++++++++++++++++++------------- 1 file changed, 23 insertions(+), 13 deletions(-) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index e959ef263e..c3112bf71a 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -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; }