diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/qcow2-snapshot.c | 67 |
1 files changed, 56 insertions, 11 deletions
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index b526a8f819..53dc1635ec 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -44,7 +44,23 @@ void qcow2_free_snapshots(BlockDriverState *bs) s->nb_snapshots = 0; } -int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) +/* + * If @repair is true, try to repair a broken snapshot table instead + * of just returning an error: + * + * - If there were snapshots with too much extra metadata, increment + * *extra_data_dropped for each. + * This requires the caller to eventually rewrite the whole snapshot + * table, which requires cluster allocation. Therefore, this should + * be done only after qcow2_check_refcounts() made sure the refcount + * structures are valid. + * (In the meantime, the image is still valid because + * qcow2_check_refcounts() does not do anything with snapshots' + * extra data.) + */ +static int qcow2_do_read_snapshots(BlockDriverState *bs, bool repair, + int *extra_data_dropped, + Error **errp) { BDRVQcow2State *s = bs->opaque; QCowSnapshotHeader h; @@ -64,6 +80,8 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) s->snapshots = g_new0(QCowSnapshot, s->nb_snapshots); for(i = 0; i < s->nb_snapshots; i++) { + bool truncate_unknown_extra_data = false; + /* Read statically sized part of the snapshot header */ offset = ROUND_UP(offset, 8); ret = bdrv_pread(bs->file, offset, &h, sizeof(h)); @@ -86,10 +104,21 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) name_size = be16_to_cpu(h.name_size); if (sn->extra_data_size > QCOW_MAX_SNAPSHOT_EXTRA_DATA) { - ret = -EFBIG; - error_setg(errp, "Too much extra metadata in snapshot table " - "entry %i", i); - goto fail; + if (!repair) { + ret = -EFBIG; + error_setg(errp, "Too much extra metadata in snapshot table " + "entry %i", i); + error_append_hint(errp, "You can force-remove this extra " + "metadata with qemu-img check -r all\n"); + goto fail; + } + + fprintf(stderr, "Discarding too much extra metadata in snapshot " + "table entry %i (%" PRIu32 " > %u)\n", + i, sn->extra_data_size, QCOW_MAX_SNAPSHOT_EXTRA_DATA); + + (*extra_data_dropped)++; + truncate_unknown_extra_data = true; } /* Read known extra data */ @@ -113,18 +142,26 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) } if (sn->extra_data_size > sizeof(extra)) { - /* Store unknown extra data */ - size_t unknown_extra_data_size = - sn->extra_data_size - sizeof(extra); + uint64_t extra_data_end; + size_t unknown_extra_data_size; + + extra_data_end = offset + sn->extra_data_size - sizeof(extra); + if (truncate_unknown_extra_data) { + sn->extra_data_size = QCOW_MAX_SNAPSHOT_EXTRA_DATA; + } + + /* Store unknown extra data */ + unknown_extra_data_size = sn->extra_data_size - sizeof(extra); sn->unknown_extra_data = g_malloc(unknown_extra_data_size); ret = bdrv_pread(bs->file, offset, sn->unknown_extra_data, unknown_extra_data_size); if (ret < 0) { - error_setg_errno(errp, -ret, "Failed to read snapshot table"); + error_setg_errno(errp, -ret, + "Failed to read snapshot table"); goto fail; } - offset += unknown_extra_data_size; + offset = extra_data_end; } /* Read snapshot ID */ @@ -163,6 +200,11 @@ fail: return ret; } +int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) +{ + return qcow2_do_read_snapshots(bs, false, NULL, errp); +} + /* add at the end of the file a new list of snapshots */ int qcow2_write_snapshots(BlockDriverState *bs) { @@ -328,6 +370,7 @@ int coroutine_fn qcow2_check_read_snapshot_table(BlockDriverState *bs, { BDRVQcow2State *s = bs->opaque; Error *local_err = NULL; + int extra_data_dropped = 0; int ret; struct { uint32_t nb_snapshots; @@ -363,7 +406,8 @@ int coroutine_fn qcow2_check_read_snapshot_table(BlockDriverState *bs, } qemu_co_mutex_unlock(&s->lock); - ret = qcow2_read_snapshots(bs, &local_err); + ret = qcow2_do_read_snapshots(bs, fix & BDRV_FIX_ERRORS, + &extra_data_dropped, &local_err); qemu_co_mutex_lock(&s->lock); if (ret < 0) { result->check_errors++; @@ -376,6 +420,7 @@ int coroutine_fn qcow2_check_read_snapshot_table(BlockDriverState *bs, return ret; } + result->corruptions += extra_data_dropped; return 0; } |