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qcow2: External file I/O

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This changes the qcow2 implementation to direct all guest data I/O to
s->data_file rather than bs->file, while metadata I/O still uses
bs->file. At the moment, this is still always the same, but soon we'll
add options to set s->data_file to an external data file.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2019-01-15 20:39:06 +01:00
parent 37be14036b
commit 966b000f49
7 changed files with 122 additions and 37 deletions
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7
block/qcow2-bitmap.c
View File

@ -778,7 +778,8 @@ static int bitmap_list_store(BlockDriverState *bs, Qcow2BitmapList *bm_list,
* directory in-place (actually, turn-off the extension), which is checked
* in qcow2_check_metadata_overlap() */
ret = qcow2_pre_write_overlap_check(
bs, in_place ? QCOW2_OL_BITMAP_DIRECTORY : 0, dir_offset, dir_size);
bs, in_place ? QCOW2_OL_BITMAP_DIRECTORY : 0, dir_offset, dir_size,
false);
if (ret < 0) {
goto fail;
}
@ -1224,7 +1225,7 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs,
memset(buf + write_size, 0, s->cluster_size - write_size);
}
ret = qcow2_pre_write_overlap_check(bs, 0, off, s->cluster_size);
ret = qcow2_pre_write_overlap_check(bs, 0, off, s->cluster_size, false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
goto fail;
@ -1292,7 +1293,7 @@ static int store_bitmap(BlockDriverState *bs, Qcow2Bitmap *bm, Error **errp)
}
ret = qcow2_pre_write_overlap_check(bs, 0, tb_offset,
tb_size * sizeof(tb[0]));
tb_size * sizeof(tb[0]), false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
goto fail;

6
block/qcow2-cache.c
View File

@ -205,13 +205,13 @@ static int qcow2_cache_entry_flush(BlockDriverState *bs, Qcow2Cache *c, int i)
if (c == s->refcount_block_cache) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_REFCOUNT_BLOCK,
c->entries[i].offset, c->table_size);
c->entries[i].offset, c->table_size, false);
} else if (c == s->l2_table_cache) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2,
c->entries[i].offset, c->table_size);
c->entries[i].offset, c->table_size, false);
} else {
ret = qcow2_pre_write_overlap_check(bs, 0,
c->entries[i].offset, c->table_size);
c->entries[i].offset, c->table_size, false);
}
if (ret < 0) {

46
block/qcow2-cluster.c
View File

@ -153,7 +153,7 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
/* the L1 position has not yet been updated, so these clusters must
* indeed be completely free */
ret = qcow2_pre_write_overlap_check(bs, 0, new_l1_table_offset,
new_l1_size2);
new_l1_size2, false);
if (ret < 0) {
goto fail;
}
@ -238,7 +238,7 @@ int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
}
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
s->l1_table_offset + 8 * l1_start_index, sizeof(buf));
s->l1_table_offset + 8 * l1_start_index, sizeof(buf), false);
if (ret < 0) {
return ret;
}
@ -490,6 +490,7 @@ static int coroutine_fn do_perform_cow_write(BlockDriverState *bs,
unsigned offset_in_cluster,
QEMUIOVector *qiov)
{
BDRVQcow2State *s = bs->opaque;
int ret;
if (qiov->size == 0) {
@ -497,13 +498,13 @@ static int coroutine_fn do_perform_cow_write(BlockDriverState *bs,
}
ret = qcow2_pre_write_overlap_check(bs, 0,
cluster_offset + offset_in_cluster, qiov->size);
cluster_offset + offset_in_cluster, qiov->size, true);
if (ret < 0) {
return ret;
}
BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
ret = bdrv_co_pwritev(bs->file, cluster_offset + offset_in_cluster,
ret = bdrv_co_pwritev(s->data_file, cluster_offset + offset_in_cluster,
qiov->size, qiov, 0);
if (ret < 0) {
return ret;
@ -607,6 +608,14 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
}
switch (type) {
case QCOW2_CLUSTER_COMPRESSED:
if (has_data_file(bs)) {
qcow2_signal_corruption(bs, true, -1, -1, "Compressed cluster "
"entry found in image with external data "
"file (L2 offset: %#" PRIx64 ", L2 index: "
"%#x)", l2_offset, l2_index);
ret = -EIO;
goto fail;
}
/* Compressed clusters can only be processed one by one */
c = 1;
*cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
@ -633,6 +642,17 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
ret = -EIO;
goto fail;
}
if (has_data_file(bs) && *cluster_offset != offset - offset_in_cluster)
{
qcow2_signal_corruption(bs, true, -1, -1,
"External data file host cluster offset %#"
PRIx64 " does not match guest cluster "
"offset: %#" PRIx64
", L2 index: %#x)", *cluster_offset,
offset - offset_in_cluster, l2_index);
ret = -EIO;
goto fail;
}
break;
default:
abort();
@ -753,6 +773,10 @@ int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
int64_t cluster_offset;
int nb_csectors;
if (has_data_file(bs)) {
return 0;
}
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
if (ret < 0) {
return ret;
@ -1243,6 +1267,13 @@ static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
*host_offset, *nb_clusters);
if (has_data_file(bs)) {
assert(*host_offset == INV_OFFSET ||
*host_offset == start_of_cluster(s, guest_offset));
*host_offset = start_of_cluster(s, guest_offset);
return 0;
}
/* Allocate new clusters */
trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
if (*host_offset == INV_OFFSET) {
@ -1919,7 +1950,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
}
ret = qcow2_pre_write_overlap_check(bs, 0, offset,
s->cluster_size);
s->cluster_size, true);
if (ret < 0) {
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
qcow2_free_clusters(bs, offset, s->cluster_size,
@ -1928,7 +1959,8 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
goto fail;
}
ret = bdrv_pwrite_zeroes(bs->file, offset, s->cluster_size, 0);
ret = bdrv_pwrite_zeroes(s->data_file, offset,
s->cluster_size, 0);
if (ret < 0) {
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
qcow2_free_clusters(bs, offset, s->cluster_size,
@ -1955,7 +1987,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
if (l2_dirty) {
ret = qcow2_pre_write_overlap_check(
bs, QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2,
slice_offset, slice_size2);
slice_offset, slice_size2, false);
if (ret < 0) {
goto fail;
}

39
block/qcow2-refcount.c
View File

@ -1156,8 +1156,20 @@ void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
int nb_clusters, enum qcow2_discard_type type)
{
BDRVQcow2State *s = bs->opaque;
QCow2ClusterType ctype = qcow2_get_cluster_type(bs, l2_entry);
switch (qcow2_get_cluster_type(bs, l2_entry)) {
if (has_data_file(bs)) {
if (s->discard_passthrough[type] &&
(ctype == QCOW2_CLUSTER_NORMAL ||
ctype == QCOW2_CLUSTER_ZERO_ALLOC))
{
bdrv_pdiscard(s->data_file, l2_entry & L2E_OFFSET_MASK,
nb_clusters << s->cluster_bits);
}
return;
}
switch (ctype) {
case QCOW2_CLUSTER_COMPRESSED:
{
int nb_csectors;
@ -1649,7 +1661,7 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
l2_table[i] = cpu_to_be64(l2_entry);
ret = qcow2_pre_write_overlap_check(bs,
QCOW2_OL_ACTIVE_L2 | QCOW2_OL_INACTIVE_L2,
l2e_offset, sizeof(uint64_t));
l2e_offset, sizeof(uint64_t), false);
if (ret < 0) {
fprintf(stderr, "ERROR: Overlap check failed\n");
res->check_errors++;
@ -1898,7 +1910,8 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
if (l2_dirty) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2,
l2_offset, s->cluster_size);
l2_offset, s->cluster_size,
false);
if (ret < 0) {
fprintf(stderr, "ERROR: Could not write L2 table; metadata "
"overlap check failed: %s\n", strerror(-ret));
@ -2366,7 +2379,7 @@ write_refblocks:
}
ret = qcow2_pre_write_overlap_check(bs, 0, refblock_offset,
s->cluster_size);
s->cluster_size, false);
if (ret < 0) {
fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
goto fail;
@ -2417,7 +2430,8 @@ write_refblocks:
}
ret = qcow2_pre_write_overlap_check(bs, 0, reftable_offset,
reftable_size * sizeof(uint64_t));
reftable_size * sizeof(uint64_t),
false);
if (ret < 0) {
fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret));
goto fail;
@ -2751,10 +2765,15 @@ QEMU_BUILD_BUG_ON(QCOW2_OL_MAX_BITNR != ARRAY_SIZE(metadata_ol_names));
* overlaps; or a negative value (-errno) on error.
*/
int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
int64_t size)
int64_t size, bool data_file)
{
int ret = qcow2_check_metadata_overlap(bs, ign, offset, size);
int ret;
if (data_file && has_data_file(bs)) {
return 0;
}
ret = qcow2_check_metadata_overlap(bs, ign, offset, size);
if (ret < 0) {
return ret;
} else if (ret > 0) {
@ -2855,7 +2874,8 @@ static int flush_refblock(BlockDriverState *bs, uint64_t **reftable,
if (reftable_index < *reftable_size && (*reftable)[reftable_index]) {
offset = (*reftable)[reftable_index];
ret = qcow2_pre_write_overlap_check(bs, 0, offset, s->cluster_size);
ret = qcow2_pre_write_overlap_check(bs, 0, offset, s->cluster_size,
false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Overlap check failed");
return ret;
@ -3121,7 +3141,8 @@ int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
/* Write the new reftable */
ret = qcow2_pre_write_overlap_check(bs, 0, new_reftable_offset,
new_reftable_size * sizeof(uint64_t));
new_reftable_size * sizeof(uint64_t),
false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Overlap check failed");
goto done;

7
block/qcow2-snapshot.c
View File

@ -184,7 +184,7 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
/* The snapshot list position has not yet been updated, so these clusters
* must indeed be completely free */
ret = qcow2_pre_write_overlap_check(bs, 0, offset, snapshots_size);
ret = qcow2_pre_write_overlap_check(bs, 0, offset, snapshots_size, false);
if (ret < 0) {
goto fail;
}
@ -389,7 +389,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
}
ret = qcow2_pre_write_overlap_check(bs, 0, sn->l1_table_offset,
s->l1_size * sizeof(uint64_t));
s->l1_size * sizeof(uint64_t), false);
if (ret < 0) {
goto fail;
}
@ -528,7 +528,8 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
}
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
s->l1_table_offset, cur_l1_bytes);
s->l1_table_offset, cur_l1_bytes,
false);
if (ret < 0) {
goto fail;
}

52
block/qcow2.c
View File

@ -140,7 +140,7 @@ static ssize_t qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen,
/* Zero fill remaining space in cluster so it has predictable
* content in case of future spec changes */
clusterlen = size_to_clusters(s, headerlen) * s->cluster_size;
assert(qcow2_pre_write_overlap_check(bs, 0, ret, clusterlen) == 0);
assert(qcow2_pre_write_overlap_check(bs, 0, ret, clusterlen, false) == 0);
ret = bdrv_pwrite_zeroes(bs->file,
ret + headerlen,
clusterlen - headerlen, 0);
@ -1965,7 +1965,7 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
*/
if (!cluster_data) {
cluster_data =
qemu_try_blockalign(bs->file->bs,
qemu_try_blockalign(s->data_file->bs,
QCOW_MAX_CRYPT_CLUSTERS
* s->cluster_size);
if (cluster_data == NULL) {
@ -1981,7 +1981,7 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_preadv(bs->file,
ret = bdrv_co_preadv(s->data_file,
cluster_offset + offset_in_cluster,
cur_bytes, &hd_qiov, 0);
qemu_co_mutex_lock(&s->lock);
@ -2140,7 +2140,7 @@ static coroutine_fn int qcow2_co_pwritev(BlockDriverState *bs, uint64_t offset,
}
ret = qcow2_pre_write_overlap_check(bs, 0,
cluster_offset + offset_in_cluster, cur_bytes);
cluster_offset + offset_in_cluster, cur_bytes, true);
if (ret < 0) {
goto fail;
}
@ -2154,7 +2154,7 @@ static coroutine_fn int qcow2_co_pwritev(BlockDriverState *bs, uint64_t offset,
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
trace_qcow2_writev_data(qemu_coroutine_self(),
cluster_offset + offset_in_cluster);
ret = bdrv_co_pwritev(bs->file,
ret = bdrv_co_pwritev(s->data_file,
cluster_offset + offset_in_cluster,
cur_bytes, &hd_qiov, 0);
qemu_co_mutex_lock(&s->lock);
@ -3356,7 +3356,7 @@ qcow2_co_copy_range_from(BlockDriverState *bs,
goto out;
case QCOW2_CLUSTER_NORMAL:
child = bs->file;
child = s->data_file;
copy_offset += offset_into_cluster(s, src_offset);
if ((copy_offset & 511) != 0) {
ret = -EIO;
@ -3426,14 +3426,14 @@ qcow2_co_copy_range_to(BlockDriverState *bs,
assert((cluster_offset & 511) == 0);
ret = qcow2_pre_write_overlap_check(bs, 0,
cluster_offset + offset_in_cluster, cur_bytes);
cluster_offset + offset_in_cluster, cur_bytes, true);
if (ret < 0) {
goto fail;
}
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_copy_range_to(src, src_offset,
bs->file,
s->data_file,
cluster_offset + offset_in_cluster,
cur_bytes, read_flags, write_flags);
qemu_co_mutex_lock(&s->lock);
@ -3588,6 +3588,17 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
int64_t old_file_size, new_file_size;
uint64_t nb_new_data_clusters, nb_new_l2_tables;
/* With a data file, preallocation means just allocating the metadata
* and forwarding the truncate request to the data file */
if (has_data_file(bs)) {
ret = preallocate_co(bs, old_length, offset);
if (ret < 0) {
error_setg_errno(errp, -ret, "Preallocation failed");
goto fail;
}
break;
}
old_file_size = bdrv_getlength(bs->file->bs);
if (old_file_size < 0) {
error_setg_errno(errp, -old_file_size,
@ -3696,6 +3707,16 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
bs->total_sectors = offset / BDRV_SECTOR_SIZE;
if (has_data_file(bs)) {
if (prealloc == PREALLOC_MODE_METADATA) {
prealloc = PREALLOC_MODE_OFF;
}
ret = bdrv_co_truncate(s->data_file, offset, prealloc, errp);
if (ret < 0) {
goto fail;
}
}
/* write updated header.size */
offset = cpu_to_be64(offset);
ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),
@ -3898,6 +3919,10 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
uint8_t *buf, *out_buf;
uint64_t cluster_offset;
if (has_data_file(bs)) {
return -ENOTSUP;
}
if (bytes == 0) {
/* align end of file to a sector boundary to ease reading with
sector based I/Os */
@ -3949,7 +3974,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
goto fail;
}
ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len);
ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len, true);
qemu_co_mutex_unlock(&s->lock);
if (ret < 0) {
goto fail;
@ -3957,8 +3982,8 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
qemu_iovec_init_buf(&hd_qiov, out_buf, out_len);
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0);
BLKDBG_EVENT(s->data_file, BLKDBG_WRITE_COMPRESSED);
ret = bdrv_co_pwritev(s->data_file, cluster_offset, out_len, &hd_qiov, 0);
if (ret < 0) {
goto fail;
}
@ -4547,6 +4572,11 @@ static int qcow2_downgrade(BlockDriverState *bs, int target_version,
return -ENOTSUP;
}
if (has_data_file(bs)) {
error_setg(errp, "Cannot downgrade an image with a data file");
return -ENOTSUP;
}
/* clear incompatible features */
if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
ret = qcow2_mark_clean(bs);

2
block/qcow2.h
View File

@ -622,7 +622,7 @@ void qcow2_process_discards(BlockDriverState *bs, int ret);
int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
int64_t size);
int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
int64_t size);
int64_t size, bool data_file);
int qcow2_inc_refcounts_imrt(BlockDriverState *bs, BdrvCheckResult *res,
void **refcount_table,
int64_t *refcount_table_size,