#include "qapi/error.h"
#include "qcow2.h"
#include "qemu/bswap.h"
+#include "qemu/memalign.h"
#include "trace.h"
int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t exact_size)
BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE);
ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset +
- new_l1_size * sizeof(uint64_t),
- (s->l1_size - new_l1_size) * sizeof(uint64_t), 0);
+ new_l1_size * L1E_SIZE,
+ (s->l1_size - new_l1_size) * L1E_SIZE, 0);
if (ret < 0) {
goto fail;
}
* l1_table in memory to avoid possible image corruption.
*/
memset(s->l1_table + new_l1_size, 0,
- (s->l1_size - new_l1_size) * sizeof(uint64_t));
+ (s->l1_size - new_l1_size) * L1E_SIZE);
return ret;
}
/* Do a sanity check on min_size before trying to calculate new_l1_size
* (this prevents overflows during the while loop for the calculation of
* new_l1_size) */
- if (min_size > INT_MAX / sizeof(uint64_t)) {
+ if (min_size > INT_MAX / L1E_SIZE) {
return -EFBIG;
}
}
QEMU_BUILD_BUG_ON(QCOW_MAX_L1_SIZE > INT_MAX);
- if (new_l1_size > QCOW_MAX_L1_SIZE / sizeof(uint64_t)) {
+ if (new_l1_size > QCOW_MAX_L1_SIZE / L1E_SIZE) {
return -EFBIG;
}
s->l1_size, new_l1_size);
#endif
- new_l1_size2 = sizeof(uint64_t) * new_l1_size;
+ new_l1_size2 = L1E_SIZE * new_l1_size;
new_l1_table = qemu_try_blockalign(bs->file->bs, new_l1_size2);
if (new_l1_table == NULL) {
return -ENOMEM;
memset(new_l1_table, 0, new_l1_size2);
if (s->l1_size) {
- memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
+ memcpy(new_l1_table, s->l1_table, s->l1_size * L1E_SIZE);
}
/* write new table (align to cluster) */
s->l1_table = new_l1_table;
old_l1_size = s->l1_size;
s->l1_size = new_l1_size;
- qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * sizeof(uint64_t),
+ qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * L1E_SIZE,
QCOW2_DISCARD_OTHER);
return 0;
fail:
uint64_t l2_offset, uint64_t **l2_slice)
{
BDRVQcow2State *s = bs->opaque;
- int start_of_slice = sizeof(uint64_t) *
+ int start_of_slice = l2_entry_size(s) *
(offset_to_l2_index(s, offset) - offset_to_l2_slice_index(s, offset));
return qcow2_cache_get(bs, s->l2_table_cache, l2_offset + start_of_slice,
BDRVQcow2State *s = bs->opaque;
int l1_start_index;
int i, ret;
- int bufsize = MAX(sizeof(uint64_t),
+ int bufsize = MAX(L1E_SIZE,
MIN(bs->file->bs->bl.request_alignment, s->cluster_size));
- int nentries = bufsize / sizeof(uint64_t);
+ int nentries = bufsize / L1E_SIZE;
g_autofree uint64_t *buf = g_try_new0(uint64_t, nentries);
if (buf == NULL) {
}
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
- s->l1_table_offset + 8 * l1_start_index, bufsize, false);
+ s->l1_table_offset + L1E_SIZE * l1_start_index, bufsize, false);
if (ret < 0) {
return ret;
}
BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
ret = bdrv_pwrite_sync(bs->file,
- s->l1_table_offset + 8 * l1_start_index,
+ s->l1_table_offset + L1E_SIZE * l1_start_index,
buf, bufsize);
if (ret < 0) {
return ret;
/* allocate a new l2 entry */
- l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
+ l2_offset = qcow2_alloc_clusters(bs, s->l2_size * l2_entry_size(s));
if (l2_offset < 0) {
ret = l2_offset;
goto fail;
/* allocate a new entry in the l2 cache */
- slice_size2 = s->l2_slice_size * sizeof(uint64_t);
+ slice_size2 = s->l2_slice_size * l2_entry_size(s);
n_slices = s->cluster_size / slice_size2;
trace_qcow2_l2_allocate_get_empty(bs, l1_index);
}
s->l1_table[l1_index] = old_l2_offset;
if (l2_offset > 0) {
- qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
+ qcow2_free_clusters(bs, l2_offset, s->l2_size * l2_entry_size(s),
QCOW2_DISCARD_ALWAYS);
}
return ret;
}
/*
- * Checks how many clusters in a given L2 slice are contiguous in the image
- * file. As soon as one of the flags in the bitmask stop_flags changes compared
- * to the first cluster, the search is stopped and the cluster is not counted
- * as contiguous. (This allows it, for example, to stop at the first compressed
- * cluster which may require a different handling)
+ * For a given L2 entry, count the number of contiguous subclusters of
+ * the same type starting from @sc_from. Compressed clusters are
+ * treated as if they were divided into subclusters of size
+ * s->subcluster_size.
+ *
+ * Return the number of contiguous subclusters and set @type to the
+ * subcluster type.
+ *
+ * If the L2 entry is invalid return -errno and set @type to
+ * QCOW2_SUBCLUSTER_INVALID.
*/
-static int count_contiguous_clusters(BlockDriverState *bs, int nb_clusters,
- int cluster_size, uint64_t *l2_slice, uint64_t stop_flags)
+static int qcow2_get_subcluster_range_type(BlockDriverState *bs,
+ uint64_t l2_entry,
+ uint64_t l2_bitmap,
+ unsigned sc_from,
+ QCow2SubclusterType *type)
{
- int i;
- QCow2ClusterType first_cluster_type;
- uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED;
- uint64_t first_entry = be64_to_cpu(l2_slice[0]);
- uint64_t offset = first_entry & mask;
+ BDRVQcow2State *s = bs->opaque;
+ uint32_t val;
- first_cluster_type = qcow2_get_cluster_type(bs, first_entry);
- if (first_cluster_type == QCOW2_CLUSTER_UNALLOCATED) {
- return 0;
+ *type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_from);
+
+ if (*type == QCOW2_SUBCLUSTER_INVALID) {
+ return -EINVAL;
+ } else if (!has_subclusters(s) || *type == QCOW2_SUBCLUSTER_COMPRESSED) {
+ return s->subclusters_per_cluster - sc_from;
}
- /* must be allocated */
- assert(first_cluster_type == QCOW2_CLUSTER_NORMAL ||
- first_cluster_type == QCOW2_CLUSTER_ZERO_ALLOC);
+ switch (*type) {
+ case QCOW2_SUBCLUSTER_NORMAL:
+ val = l2_bitmap | QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from);
+ return cto32(val) - sc_from;
- for (i = 0; i < nb_clusters; i++) {
- uint64_t l2_entry = be64_to_cpu(l2_slice[i]) & mask;
- if (offset + (uint64_t) i * cluster_size != l2_entry) {
- break;
- }
- }
+ case QCOW2_SUBCLUSTER_ZERO_PLAIN:
+ case QCOW2_SUBCLUSTER_ZERO_ALLOC:
+ val = (l2_bitmap | QCOW_OFLAG_SUB_ZERO_RANGE(0, sc_from)) >> 32;
+ return cto32(val) - sc_from;
+
+ case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
+ val = ((l2_bitmap >> 32) | l2_bitmap)
+ & ~QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from);
+ return ctz32(val) - sc_from;
- return i;
+ default:
+ g_assert_not_reached();
+ }
}
/*
- * Checks how many consecutive unallocated clusters in a given L2
- * slice have the same cluster type.
+ * Return the number of contiguous subclusters of the exact same type
+ * in a given L2 slice, starting from cluster @l2_index, subcluster
+ * @sc_index. Allocated subclusters are required to be contiguous in
+ * the image file.
+ * At most @nb_clusters are checked (note that this means clusters,
+ * not subclusters).
+ * Compressed clusters are always processed one by one but for the
+ * purpose of this count they are treated as if they were divided into
+ * subclusters of size s->subcluster_size.
+ * On failure return -errno and update @l2_index to point to the
+ * invalid entry.
*/
-static int count_contiguous_clusters_unallocated(BlockDriverState *bs,
- int nb_clusters,
- uint64_t *l2_slice,
- QCow2ClusterType wanted_type)
+static int count_contiguous_subclusters(BlockDriverState *bs, int nb_clusters,
+ unsigned sc_index, uint64_t *l2_slice,
+ unsigned *l2_index)
{
- int i;
+ BDRVQcow2State *s = bs->opaque;
+ int i, count = 0;
+ bool check_offset = false;
+ uint64_t expected_offset = 0;
+ QCow2SubclusterType expected_type = QCOW2_SUBCLUSTER_NORMAL, type;
- assert(wanted_type == QCOW2_CLUSTER_ZERO_PLAIN ||
- wanted_type == QCOW2_CLUSTER_UNALLOCATED);
- for (i = 0; i < nb_clusters; i++) {
- uint64_t entry = be64_to_cpu(l2_slice[i]);
- QCow2ClusterType type = qcow2_get_cluster_type(bs, entry);
+ assert(*l2_index + nb_clusters <= s->l2_slice_size);
- if (type != wanted_type) {
+ for (i = 0; i < nb_clusters; i++) {
+ unsigned first_sc = (i == 0) ? sc_index : 0;
+ uint64_t l2_entry = get_l2_entry(s, l2_slice, *l2_index + i);
+ uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, *l2_index + i);
+ int ret = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap,
+ first_sc, &type);
+ if (ret < 0) {
+ *l2_index += i; /* Point to the invalid entry */
+ return -EIO;
+ }
+ if (i == 0) {
+ if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
+ /* Compressed clusters are always processed one by one */
+ return ret;
+ }
+ expected_type = type;
+ expected_offset = l2_entry & L2E_OFFSET_MASK;
+ check_offset = (type == QCOW2_SUBCLUSTER_NORMAL ||
+ type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
+ type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC);
+ } else if (type != expected_type) {
+ break;
+ } else if (check_offset) {
+ expected_offset += s->cluster_size;
+ if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) {
+ break;
+ }
+ }
+ count += ret;
+ /* Stop if there are type changes before the end of the cluster */
+ if (first_sc + ret < s->subclusters_per_cluster) {
break;
}
}
- return i;
+ return count;
}
static int coroutine_fn do_perform_cow_read(BlockDriverState *bs,
return -ENOMEDIUM;
}
- /* Call .bdrv_co_readv() directly instead of using the public block-layer
+ /*
+ * We never deal with requests that don't satisfy
+ * bdrv_check_qiov_request(), and aligning requests to clusters never
+ * breaks this condition. So, do some assertions before calling
+ * bs->drv->bdrv_co_preadv_part() which has int64_t arguments.
+ */
+ assert(src_cluster_offset <= INT64_MAX);
+ assert(src_cluster_offset + offset_in_cluster <= INT64_MAX);
+ /* Cast qiov->size to uint64_t to silence a compiler warning on -m32 */
+ assert((uint64_t)qiov->size <= INT64_MAX);
+ bdrv_check_qiov_request(src_cluster_offset + offset_in_cluster, qiov->size,
+ qiov, 0, &error_abort);
+ /*
+ * Call .bdrv_co_readv() directly instead of using the public block-layer
* interface. This avoids double I/O throttling and request tracking,
* which can lead to deadlock when block layer copy-on-read is enabled.
*/
/*
- * get_cluster_offset
+ * get_host_offset
*
- * For a given offset of the virtual disk, find the cluster type and offset in
- * the qcow2 file. The offset is stored in *cluster_offset.
+ * For a given offset of the virtual disk find the equivalent host
+ * offset in the qcow2 file and store it in *host_offset. Neither
+ * offset needs to be aligned to a cluster boundary.
+ *
+ * If the cluster is unallocated then *host_offset will be 0.
+ * If the cluster is compressed then *host_offset will contain the l2 entry.
*
* On entry, *bytes is the maximum number of contiguous bytes starting at
* offset that we are interested in.
*
* On exit, *bytes is the number of bytes starting at offset that have the same
- * cluster type and (if applicable) are stored contiguously in the image file.
- * Compressed clusters are always returned one by one.
+ * subcluster type and (if applicable) are stored contiguously in the image
+ * file. The subcluster type is stored in *subcluster_type.
+ * Compressed clusters are always processed one by one.
*
- * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
- * cases.
+ * Returns 0 on success, -errno in error cases.
*/
-int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
- unsigned int *bytes, uint64_t *cluster_offset)
+int qcow2_get_host_offset(BlockDriverState *bs, uint64_t offset,
+ unsigned int *bytes, uint64_t *host_offset,
+ QCow2SubclusterType *subcluster_type)
{
BDRVQcow2State *s = bs->opaque;
- unsigned int l2_index;
- uint64_t l1_index, l2_offset, *l2_slice;
- int c;
+ unsigned int l2_index, sc_index;
+ uint64_t l1_index, l2_offset, *l2_slice, l2_entry, l2_bitmap;
+ int sc;
unsigned int offset_in_cluster;
uint64_t bytes_available, bytes_needed, nb_clusters;
- QCow2ClusterType type;
+ QCow2SubclusterType type;
int ret;
offset_in_cluster = offset_into_cluster(s, offset);
bytes_needed = bytes_available;
}
- *cluster_offset = 0;
+ *host_offset = 0;
/* seek to the l2 offset in the l1 table */
l1_index = offset_to_l1_index(s, offset);
if (l1_index >= s->l1_size) {
- type = QCOW2_CLUSTER_UNALLOCATED;
+ type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN;
goto out;
}
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
if (!l2_offset) {
- type = QCOW2_CLUSTER_UNALLOCATED;
+ type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN;
goto out;
}
/* find the cluster offset for the given disk offset */
l2_index = offset_to_l2_slice_index(s, offset);
- *cluster_offset = be64_to_cpu(l2_slice[l2_index]);
+ sc_index = offset_to_sc_index(s, offset);
+ l2_entry = get_l2_entry(s, l2_slice, l2_index);
+ l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
nb_clusters = size_to_clusters(s, bytes_needed);
/* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned
* true */
assert(nb_clusters <= INT_MAX);
- type = qcow2_get_cluster_type(bs, *cluster_offset);
- if (s->qcow_version < 3 && (type == QCOW2_CLUSTER_ZERO_PLAIN ||
- type == QCOW2_CLUSTER_ZERO_ALLOC)) {
+ type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index);
+ if (s->qcow_version < 3 && (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
+ type == QCOW2_SUBCLUSTER_ZERO_ALLOC)) {
qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found"
" in pre-v3 image (L2 offset: %#" PRIx64
", L2 index: %#x)", l2_offset, l2_index);
goto fail;
}
switch (type) {
- case QCOW2_CLUSTER_COMPRESSED:
+ case QCOW2_SUBCLUSTER_INVALID:
+ break; /* This is handled by count_contiguous_subclusters() below */
+ case QCOW2_SUBCLUSTER_COMPRESSED:
if (has_data_file(bs)) {
qcow2_signal_corruption(bs, true, -1, -1, "Compressed cluster "
"entry found in image with external data "
ret = -EIO;
goto fail;
}
- /* Compressed clusters can only be processed one by one */
- c = 1;
- *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
+ *host_offset = l2_entry;
break;
- case QCOW2_CLUSTER_ZERO_PLAIN:
- case QCOW2_CLUSTER_UNALLOCATED:
- /* how many empty clusters ? */
- c = count_contiguous_clusters_unallocated(bs, nb_clusters,
- &l2_slice[l2_index], type);
- *cluster_offset = 0;
+ case QCOW2_SUBCLUSTER_ZERO_PLAIN:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
break;
- case QCOW2_CLUSTER_ZERO_ALLOC:
- case QCOW2_CLUSTER_NORMAL:
- /* how many allocated clusters ? */
- c = count_contiguous_clusters(bs, nb_clusters, s->cluster_size,
- &l2_slice[l2_index], QCOW_OFLAG_ZERO);
- *cluster_offset &= L2E_OFFSET_MASK;
- if (offset_into_cluster(s, *cluster_offset)) {
+ case QCOW2_SUBCLUSTER_ZERO_ALLOC:
+ case QCOW2_SUBCLUSTER_NORMAL:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: {
+ uint64_t host_cluster_offset = l2_entry & L2E_OFFSET_MASK;
+ *host_offset = host_cluster_offset + offset_in_cluster;
+ if (offset_into_cluster(s, host_cluster_offset)) {
qcow2_signal_corruption(bs, true, -1, -1,
"Cluster allocation offset %#"
PRIx64 " unaligned (L2 offset: %#" PRIx64
- ", L2 index: %#x)", *cluster_offset,
+ ", L2 index: %#x)", host_cluster_offset,
l2_offset, l2_index);
ret = -EIO;
goto fail;
}
- if (has_data_file(bs) && *cluster_offset != offset - offset_in_cluster)
- {
+ if (has_data_file(bs) && *host_offset != offset) {
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,
+ ", L2 index: %#x)", host_cluster_offset,
offset - offset_in_cluster, l2_index);
ret = -EIO;
goto fail;
}
break;
+ }
default:
abort();
}
+ sc = count_contiguous_subclusters(bs, nb_clusters, sc_index,
+ l2_slice, &l2_index);
+ if (sc < 0) {
+ qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster entry found "
+ " (L2 offset: %#" PRIx64 ", L2 index: %#x)",
+ l2_offset, l2_index);
+ ret = -EIO;
+ goto fail;
+ }
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
- bytes_available = (int64_t)c * s->cluster_size;
+ bytes_available = ((int64_t)sc + sc_index) << s->subcluster_bits;
out:
if (bytes_available > bytes_needed) {
assert(bytes_available - offset_in_cluster <= UINT_MAX);
*bytes = bytes_available - offset_in_cluster;
- return type;
+ *subcluster_type = type;
+
+ return 0;
fail:
qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice);
/* Then decrease the refcount of the old table */
if (l2_offset) {
- qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
+ qcow2_free_clusters(bs, l2_offset, s->l2_size * l2_entry_size(s),
QCOW2_DISCARD_OTHER);
}
/* Compression can't overwrite anything. Fail if the cluster was already
* allocated. */
- cluster_offset = be64_to_cpu(l2_slice[l2_index]);
+ cluster_offset = get_l2_entry(s, l2_slice, l2_index);
if (cluster_offset & L2E_OFFSET_MASK) {
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
return -EIO;
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
- l2_slice[l2_index] = cpu_to_be64(cluster_offset);
+ set_l2_entry(s, l2_slice, l2_index, cluster_offset);
+ if (has_subclusters(s)) {
+ set_l2_bitmap(s, l2_slice, l2_index, 0);
+ }
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
*host_offset = cluster_offset & s->cluster_offset_mask;
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
assert(l2_index + m->nb_clusters <= s->l2_slice_size);
+ assert(m->cow_end.offset + m->cow_end.nb_bytes <=
+ m->nb_clusters << s->cluster_bits);
for (i = 0; i < m->nb_clusters; i++) {
- uint64_t offset = cluster_offset + (i << s->cluster_bits);
+ uint64_t offset = cluster_offset + ((uint64_t)i << s->cluster_bits);
/* if two concurrent writes happen to the same unallocated cluster
* each write allocates separate cluster and writes data concurrently.
* The first one to complete updates l2 table with pointer to its
* cluster the second one has to do RMW (which is done above by
* perform_cow()), update l2 table with its cluster pointer and free
* old cluster. This is what this loop does */
- if (l2_slice[l2_index + i] != 0) {
- old_cluster[j++] = l2_slice[l2_index + i];
+ if (get_l2_entry(s, l2_slice, l2_index + i) != 0) {
+ old_cluster[j++] = get_l2_entry(s, l2_slice, l2_index + i);
}
/* The offset must fit in the offset field of the L2 table entry */
assert((offset & L2E_OFFSET_MASK) == offset);
- l2_slice[l2_index + i] = cpu_to_be64(offset | QCOW_OFLAG_COPIED);
+ set_l2_entry(s, l2_slice, l2_index + i, offset | QCOW_OFLAG_COPIED);
+
+ /* Update bitmap with the subclusters that were just written */
+ if (has_subclusters(s) && !m->prealloc) {
+ uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ unsigned written_from = m->cow_start.offset;
+ unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes;
+ int first_sc, last_sc;
+ /* Narrow written_from and written_to down to the current cluster */
+ written_from = MAX(written_from, i << s->cluster_bits);
+ written_to = MIN(written_to, (i + 1) << s->cluster_bits);
+ assert(written_from < written_to);
+ first_sc = offset_to_sc_index(s, written_from);
+ last_sc = offset_to_sc_index(s, written_to - 1);
+ l2_bitmap |= QCOW_OFLAG_SUB_ALLOC_RANGE(first_sc, last_sc + 1);
+ l2_bitmap &= ~QCOW_OFLAG_SUB_ZERO_RANGE(first_sc, last_sc + 1);
+ set_l2_bitmap(s, l2_slice, l2_index + i, l2_bitmap);
+ }
}
*/
if (!m->keep_old_clusters && j != 0) {
for (i = 0; i < j; i++) {
- qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
- QCOW2_DISCARD_NEVER);
+ qcow2_free_any_cluster(bs, old_cluster[i], QCOW2_DISCARD_NEVER);
}
}
}
/*
- * Returns the number of contiguous clusters that can be used for an allocating
- * write, but require COW to be performed (this includes yet unallocated space,
- * which must copy from the backing file)
+ * For a given write request, create a new QCowL2Meta structure, add
+ * it to @m and the BDRVQcow2State.cluster_allocs list. If the write
+ * request does not need copy-on-write or changes to the L2 metadata
+ * then this function does nothing.
+ *
+ * @host_cluster_offset points to the beginning of the first cluster.
+ *
+ * @guest_offset and @bytes indicate the offset and length of the
+ * request.
+ *
+ * @l2_slice contains the L2 entries of all clusters involved in this
+ * write request.
+ *
+ * If @keep_old is true it means that the clusters were already
+ * allocated and will be overwritten. If false then the clusters are
+ * new and we have to decrease the reference count of the old ones.
+ *
+ * Returns 0 on success, -errno on failure.
*/
-static int count_cow_clusters(BlockDriverState *bs, int nb_clusters,
- uint64_t *l2_slice, int l2_index)
+static int calculate_l2_meta(BlockDriverState *bs, uint64_t host_cluster_offset,
+ uint64_t guest_offset, unsigned bytes,
+ uint64_t *l2_slice, QCowL2Meta **m, bool keep_old)
{
+ BDRVQcow2State *s = bs->opaque;
+ int sc_index, l2_index = offset_to_l2_slice_index(s, guest_offset);
+ uint64_t l2_entry, l2_bitmap;
+ unsigned cow_start_from, cow_end_to;
+ unsigned cow_start_to = offset_into_cluster(s, guest_offset);
+ unsigned cow_end_from = cow_start_to + bytes;
+ unsigned nb_clusters = size_to_clusters(s, cow_end_from);
+ QCowL2Meta *old_m = *m;
+ QCow2SubclusterType type;
int i;
+ bool skip_cow = keep_old;
+ assert(nb_clusters <= s->l2_slice_size - l2_index);
+
+ /* Check the type of all affected subclusters */
for (i = 0; i < nb_clusters; i++) {
- uint64_t l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
- QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry);
+ l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ if (skip_cow) {
+ unsigned write_from = MAX(cow_start_to, i << s->cluster_bits);
+ unsigned write_to = MIN(cow_end_from, (i + 1) << s->cluster_bits);
+ int first_sc = offset_to_sc_index(s, write_from);
+ int last_sc = offset_to_sc_index(s, write_to - 1);
+ int cnt = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap,
+ first_sc, &type);
+ /* Is any of the subclusters of type != QCOW2_SUBCLUSTER_NORMAL ? */
+ if (type != QCOW2_SUBCLUSTER_NORMAL || first_sc + cnt <= last_sc) {
+ skip_cow = false;
+ }
+ } else {
+ /* If we can't skip the cow we can still look for invalid entries */
+ type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, 0);
+ }
+ if (type == QCOW2_SUBCLUSTER_INVALID) {
+ int l1_index = offset_to_l1_index(s, guest_offset);
+ uint64_t l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
+ qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster "
+ "entry found (L2 offset: %#" PRIx64
+ ", L2 index: %#x)",
+ l2_offset, l2_index + i);
+ return -EIO;
+ }
+ }
+
+ if (skip_cow) {
+ return 0;
+ }
- switch(cluster_type) {
- case QCOW2_CLUSTER_NORMAL:
- if (l2_entry & QCOW_OFLAG_COPIED) {
- goto out;
+ /* Get the L2 entry of the first cluster */
+ l2_entry = get_l2_entry(s, l2_slice, l2_index);
+ l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
+ sc_index = offset_to_sc_index(s, guest_offset);
+ type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index);
+
+ if (!keep_old) {
+ switch (type) {
+ case QCOW2_SUBCLUSTER_COMPRESSED:
+ cow_start_from = 0;
+ break;
+ case QCOW2_SUBCLUSTER_NORMAL:
+ case QCOW2_SUBCLUSTER_ZERO_ALLOC:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
+ if (has_subclusters(s)) {
+ /* Skip all leading zero and unallocated subclusters */
+ uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC;
+ cow_start_from =
+ MIN(sc_index, ctz32(alloc_bitmap)) << s->subcluster_bits;
+ } else {
+ cow_start_from = 0;
}
break;
- case QCOW2_CLUSTER_UNALLOCATED:
- case QCOW2_CLUSTER_COMPRESSED:
- case QCOW2_CLUSTER_ZERO_PLAIN:
- case QCOW2_CLUSTER_ZERO_ALLOC:
+ case QCOW2_SUBCLUSTER_ZERO_PLAIN:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
+ cow_start_from = sc_index << s->subcluster_bits;
+ break;
+ default:
+ g_assert_not_reached();
+ }
+ } else {
+ switch (type) {
+ case QCOW2_SUBCLUSTER_NORMAL:
+ cow_start_from = cow_start_to;
+ break;
+ case QCOW2_SUBCLUSTER_ZERO_ALLOC:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
+ cow_start_from = sc_index << s->subcluster_bits;
break;
default:
- abort();
+ g_assert_not_reached();
+ }
+ }
+
+ /* Get the L2 entry of the last cluster */
+ l2_index += nb_clusters - 1;
+ l2_entry = get_l2_entry(s, l2_slice, l2_index);
+ l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
+ sc_index = offset_to_sc_index(s, guest_offset + bytes - 1);
+ type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index);
+
+ if (!keep_old) {
+ switch (type) {
+ case QCOW2_SUBCLUSTER_COMPRESSED:
+ cow_end_to = ROUND_UP(cow_end_from, s->cluster_size);
+ break;
+ case QCOW2_SUBCLUSTER_NORMAL:
+ case QCOW2_SUBCLUSTER_ZERO_ALLOC:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
+ cow_end_to = ROUND_UP(cow_end_from, s->cluster_size);
+ if (has_subclusters(s)) {
+ /* Skip all trailing zero and unallocated subclusters */
+ uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC;
+ cow_end_to -=
+ MIN(s->subclusters_per_cluster - sc_index - 1,
+ clz32(alloc_bitmap)) << s->subcluster_bits;
+ }
+ break;
+ case QCOW2_SUBCLUSTER_ZERO_PLAIN:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
+ cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size);
+ break;
+ default:
+ g_assert_not_reached();
+ }
+ } else {
+ switch (type) {
+ case QCOW2_SUBCLUSTER_NORMAL:
+ cow_end_to = cow_end_from;
+ break;
+ case QCOW2_SUBCLUSTER_ZERO_ALLOC:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
+ cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size);
+ break;
+ default:
+ g_assert_not_reached();
+ }
+ }
+
+ *m = g_malloc0(sizeof(**m));
+ **m = (QCowL2Meta) {
+ .next = old_m,
+
+ .alloc_offset = host_cluster_offset,
+ .offset = start_of_cluster(s, guest_offset),
+ .nb_clusters = nb_clusters,
+
+ .keep_old_clusters = keep_old,
+
+ .cow_start = {
+ .offset = cow_start_from,
+ .nb_bytes = cow_start_to - cow_start_from,
+ },
+ .cow_end = {
+ .offset = cow_end_from,
+ .nb_bytes = cow_end_to - cow_end_from,
+ },
+ };
+
+ qemu_co_queue_init(&(*m)->dependent_requests);
+ QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
+
+ return 0;
+}
+
+/*
+ * Returns true if writing to the cluster pointed to by @l2_entry
+ * requires a new allocation (that is, if the cluster is unallocated
+ * or has refcount > 1 and therefore cannot be written in-place).
+ */
+static bool cluster_needs_new_alloc(BlockDriverState *bs, uint64_t l2_entry)
+{
+ switch (qcow2_get_cluster_type(bs, l2_entry)) {
+ case QCOW2_CLUSTER_NORMAL:
+ case QCOW2_CLUSTER_ZERO_ALLOC:
+ if (l2_entry & QCOW_OFLAG_COPIED) {
+ return false;
+ }
+ /* fallthrough */
+ case QCOW2_CLUSTER_UNALLOCATED:
+ case QCOW2_CLUSTER_COMPRESSED:
+ case QCOW2_CLUSTER_ZERO_PLAIN:
+ return true;
+ default:
+ abort();
+ }
+}
+
+/*
+ * Returns the number of contiguous clusters that can be written to
+ * using one single write request, starting from @l2_index.
+ * At most @nb_clusters are checked.
+ *
+ * If @new_alloc is true this counts clusters that are either
+ * unallocated, or allocated but with refcount > 1 (so they need to be
+ * newly allocated and COWed).
+ *
+ * If @new_alloc is false this counts clusters that are already
+ * allocated and can be overwritten in-place (this includes clusters
+ * of type QCOW2_CLUSTER_ZERO_ALLOC).
+ */
+static int count_single_write_clusters(BlockDriverState *bs, int nb_clusters,
+ uint64_t *l2_slice, int l2_index,
+ bool new_alloc)
+{
+ BDRVQcow2State *s = bs->opaque;
+ uint64_t l2_entry = get_l2_entry(s, l2_slice, l2_index);
+ uint64_t expected_offset = l2_entry & L2E_OFFSET_MASK;
+ int i;
+
+ for (i = 0; i < nb_clusters; i++) {
+ l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ if (cluster_needs_new_alloc(bs, l2_entry) != new_alloc) {
+ break;
+ }
+ if (!new_alloc) {
+ if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) {
+ break;
+ }
+ expected_offset += s->cluster_size;
}
}
-out:
assert(i <= nb_clusters);
return i;
}
uint64_t start = guest_offset;
uint64_t end = start + bytes;
- uint64_t old_start = l2meta_cow_start(old_alloc);
- uint64_t old_end = l2meta_cow_end(old_alloc);
+ uint64_t old_start = start_of_cluster(s, l2meta_cow_start(old_alloc));
+ uint64_t old_end = ROUND_UP(l2meta_cow_end(old_alloc), s->cluster_size);
if (end <= old_start || start >= old_end) {
/* No intersection */
+ continue;
+ }
+
+ if (old_alloc->keep_old_clusters &&
+ (end <= l2meta_cow_start(old_alloc) ||
+ start >= l2meta_cow_end(old_alloc)))
+ {
+ /*
+ * Clusters intersect but COW areas don't. And cluster itself is
+ * already allocated. So, there is no actual conflict.
+ */
+ continue;
+ }
+
+ /* Conflict */
+
+ if (start < old_start) {
+ /* Stop at the start of a running allocation */
+ bytes = old_start - start;
} else {
- if (start < old_start) {
- /* Stop at the start of a running allocation */
- bytes = old_start - start;
- } else {
- bytes = 0;
- }
+ bytes = 0;
+ }
- /* Stop if already an l2meta exists. After yielding, it wouldn't
- * be valid any more, so we'd have to clean up the old L2Metas
- * and deal with requests depending on them before starting to
- * gather new ones. Not worth the trouble. */
- if (bytes == 0 && *m) {
- *cur_bytes = 0;
- return 0;
- }
+ /*
+ * Stop if an l2meta already exists. After yielding, it wouldn't
+ * be valid any more, so we'd have to clean up the old L2Metas
+ * and deal with requests depending on them before starting to
+ * gather new ones. Not worth the trouble.
+ */
+ if (bytes == 0 && *m) {
+ *cur_bytes = 0;
+ return 0;
+ }
- if (bytes == 0) {
- /* Wait for the dependency to complete. We need to recheck
- * the free/allocated clusters when we continue. */
- qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock);
- return -EAGAIN;
- }
+ if (bytes == 0) {
+ /*
+ * Wait for the dependency to complete. We need to recheck
+ * the free/allocated clusters when we continue.
+ */
+ qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock);
+ return -EAGAIN;
}
}
}
/*
- * Checks how many already allocated clusters that don't require a copy on
- * write there are at the given guest_offset (up to *bytes). If *host_offset is
- * not INV_OFFSET, only physically contiguous clusters beginning at this host
- * offset are counted.
+ * Checks how many already allocated clusters that don't require a new
+ * allocation there are at the given guest_offset (up to *bytes).
+ * If *host_offset is not INV_OFFSET, only physically contiguous clusters
+ * beginning at this host offset are counted.
*
* Note that guest_offset may not be cluster aligned. In this case, the
* returned *host_offset points to exact byte referenced by guest_offset and
* Returns:
* 0: if no allocated clusters are available at the given offset.
* *bytes is normally unchanged. It is set to 0 if the cluster
- * is allocated and doesn't need COW, but doesn't have the right
- * physical offset.
+ * is allocated and can be overwritten in-place but doesn't have
+ * the right physical offset.
*
- * 1: if allocated clusters that don't require a COW are available at
- * the requested offset. *bytes may have decreased and describes
- * the length of the area that can be written to.
+ * 1: if allocated clusters that can be overwritten in place are
+ * available at the requested offset. *bytes may have decreased
+ * and describes the length of the area that can be written to.
*
* -errno: in error cases
*/
{
BDRVQcow2State *s = bs->opaque;
int l2_index;
- uint64_t cluster_offset;
+ uint64_t l2_entry, cluster_offset;
uint64_t *l2_slice;
uint64_t nb_clusters;
unsigned int keep_clusters;
l2_index = offset_to_l2_slice_index(s, guest_offset);
nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
- assert(nb_clusters <= INT_MAX);
+ /* Limit total byte count to BDRV_REQUEST_MAX_BYTES */
+ nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits);
/* Find L2 entry for the first involved cluster */
ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
return ret;
}
- cluster_offset = be64_to_cpu(l2_slice[l2_index]);
+ l2_entry = get_l2_entry(s, l2_slice, l2_index);
+ cluster_offset = l2_entry & L2E_OFFSET_MASK;
- /* Check how many clusters are already allocated and don't need COW */
- if (qcow2_get_cluster_type(bs, cluster_offset) == QCOW2_CLUSTER_NORMAL
- && (cluster_offset & QCOW_OFLAG_COPIED))
- {
- /* If a specific host_offset is required, check it */
- bool offset_matches =
- (cluster_offset & L2E_OFFSET_MASK) == *host_offset;
-
- if (offset_into_cluster(s, cluster_offset & L2E_OFFSET_MASK)) {
- qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset "
- "%#llx unaligned (guest offset: %#" PRIx64
- ")", cluster_offset & L2E_OFFSET_MASK,
- guest_offset);
+ if (!cluster_needs_new_alloc(bs, l2_entry)) {
+ if (offset_into_cluster(s, cluster_offset)) {
+ qcow2_signal_corruption(bs, true, -1, -1, "%s cluster offset "
+ "%#" PRIx64 " unaligned (guest offset: %#"
+ PRIx64 ")", l2_entry & QCOW_OFLAG_ZERO ?
+ "Preallocated zero" : "Data",
+ cluster_offset, guest_offset);
ret = -EIO;
goto out;
}
- if (*host_offset != INV_OFFSET && !offset_matches) {
+ /* If a specific host_offset is required, check it */
+ if (*host_offset != INV_OFFSET && cluster_offset != *host_offset) {
*bytes = 0;
ret = 0;
goto out;
}
/* We keep all QCOW_OFLAG_COPIED clusters */
- keep_clusters =
- count_contiguous_clusters(bs, nb_clusters, s->cluster_size,
- &l2_slice[l2_index],
- QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO);
+ keep_clusters = count_single_write_clusters(bs, nb_clusters, l2_slice,
+ l2_index, false);
assert(keep_clusters <= nb_clusters);
*bytes = MIN(*bytes,
keep_clusters * s->cluster_size
- offset_into_cluster(s, guest_offset));
+ assert(*bytes != 0);
+
+ ret = calculate_l2_meta(bs, cluster_offset, guest_offset,
+ *bytes, l2_slice, m, true);
+ if (ret < 0) {
+ goto out;
+ }
ret = 1;
} else {
/* Only return a host offset if we actually made progress. Otherwise we
* would make requirements for handle_alloc() that it can't fulfill */
if (ret > 0) {
- *host_offset = (cluster_offset & L2E_OFFSET_MASK)
- + offset_into_cluster(s, guest_offset);
+ *host_offset = cluster_offset + offset_into_cluster(s, guest_offset);
}
return ret;
}
/*
- * Allocates new clusters for an area that either is yet unallocated or needs a
- * copy on write. If *host_offset is not INV_OFFSET, clusters are only
- * allocated if the new allocation can match the specified host offset.
+ * Allocates new clusters for an area that is either still unallocated or
+ * cannot be overwritten in-place. If *host_offset is not INV_OFFSET,
+ * clusters are only allocated if the new allocation can match the specified
+ * host offset.
*
* Note that guest_offset may not be cluster aligned. In this case, the
* returned *host_offset points to exact byte referenced by guest_offset and
BDRVQcow2State *s = bs->opaque;
int l2_index;
uint64_t *l2_slice;
- uint64_t entry;
uint64_t nb_clusters;
int ret;
- bool keep_old_clusters = false;
- uint64_t alloc_cluster_offset = INV_OFFSET;
+ uint64_t alloc_cluster_offset;
trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset,
*bytes);
l2_index = offset_to_l2_slice_index(s, guest_offset);
nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
- assert(nb_clusters <= INT_MAX);
-
- /* Limit total allocation byte count to INT_MAX */
- nb_clusters = MIN(nb_clusters, INT_MAX >> s->cluster_bits);
+ /* Limit total allocation byte count to BDRV_REQUEST_MAX_BYTES */
+ nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits);
/* Find L2 entry for the first involved cluster */
ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
return ret;
}
- entry = be64_to_cpu(l2_slice[l2_index]);
- nb_clusters = count_cow_clusters(bs, nb_clusters, l2_slice, l2_index);
+ nb_clusters = count_single_write_clusters(bs, nb_clusters,
+ l2_slice, l2_index, true);
/* This function is only called when there were no non-COW clusters, so if
* we can't find any unallocated or COW clusters either, something is
* wrong with our code. */
assert(nb_clusters > 0);
- if (qcow2_get_cluster_type(bs, entry) == QCOW2_CLUSTER_ZERO_ALLOC &&
- (entry & QCOW_OFLAG_COPIED) &&
- (*host_offset == INV_OFFSET ||
- start_of_cluster(s, *host_offset) == (entry & L2E_OFFSET_MASK)))
- {
- int preallocated_nb_clusters;
-
- if (offset_into_cluster(s, entry & L2E_OFFSET_MASK)) {
- qcow2_signal_corruption(bs, true, -1, -1, "Preallocated zero "
- "cluster offset %#llx unaligned (guest "
- "offset: %#" PRIx64 ")",
- entry & L2E_OFFSET_MASK, guest_offset);
- ret = -EIO;
- goto fail;
- }
-
- /* Try to reuse preallocated zero clusters; contiguous normal clusters
- * would be fine, too, but count_cow_clusters() above has limited
- * nb_clusters already to a range of COW clusters */
- preallocated_nb_clusters =
- count_contiguous_clusters(bs, nb_clusters, s->cluster_size,
- &l2_slice[l2_index], QCOW_OFLAG_COPIED);
- assert(preallocated_nb_clusters > 0);
-
- nb_clusters = preallocated_nb_clusters;
- alloc_cluster_offset = entry & L2E_OFFSET_MASK;
-
- /* We want to reuse these clusters, so qcow2_alloc_cluster_link_l2()
- * should not free them. */
- keep_old_clusters = true;
+ /* Allocate at a given offset in the image file */
+ alloc_cluster_offset = *host_offset == INV_OFFSET ? INV_OFFSET :
+ start_of_cluster(s, *host_offset);
+ ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
+ &nb_clusters);
+ if (ret < 0) {
+ goto out;
}
- qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
-
- if (alloc_cluster_offset == INV_OFFSET) {
- /* Allocate, if necessary at a given offset in the image file */
- alloc_cluster_offset = *host_offset == INV_OFFSET ? INV_OFFSET :
- start_of_cluster(s, *host_offset);
- ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
- &nb_clusters);
- if (ret < 0) {
- goto fail;
- }
-
- /* Can't extend contiguous allocation */
- if (nb_clusters == 0) {
- *bytes = 0;
- return 0;
- }
-
- assert(alloc_cluster_offset != INV_OFFSET);
+ /* Can't extend contiguous allocation */
+ if (nb_clusters == 0) {
+ *bytes = 0;
+ ret = 0;
+ goto out;
}
+ assert(alloc_cluster_offset != INV_OFFSET);
+
/*
* Save info needed for meta data update.
*
uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset);
int avail_bytes = nb_clusters << s->cluster_bits;
int nb_bytes = MIN(requested_bytes, avail_bytes);
- QCowL2Meta *old_m = *m;
-
- *m = g_malloc0(sizeof(**m));
-
- **m = (QCowL2Meta) {
- .next = old_m,
-
- .alloc_offset = alloc_cluster_offset,
- .offset = start_of_cluster(s, guest_offset),
- .nb_clusters = nb_clusters,
-
- .keep_old_clusters = keep_old_clusters,
-
- .cow_start = {
- .offset = 0,
- .nb_bytes = offset_into_cluster(s, guest_offset),
- },
- .cow_end = {
- .offset = nb_bytes,
- .nb_bytes = avail_bytes - nb_bytes,
- },
- };
- qemu_co_queue_init(&(*m)->dependent_requests);
- QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
*host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
*bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset));
assert(*bytes != 0);
- return 1;
-
-fail:
- if (*m && (*m)->nb_clusters > 0) {
- QLIST_REMOVE(*m, next_in_flight);
+ ret = calculate_l2_meta(bs, alloc_cluster_offset, guest_offset, *bytes,
+ l2_slice, m, false);
+ if (ret < 0) {
+ goto out;
}
+
+ ret = 1;
+
+out:
+ qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
return ret;
}
/*
- * alloc_cluster_offset
+ * For a given area on the virtual disk defined by @offset and @bytes,
+ * find the corresponding area on the qcow2 image, allocating new
+ * clusters (or subclusters) if necessary. The result can span a
+ * combination of allocated and previously unallocated clusters.
*
- * For a given offset on the virtual disk, find the cluster offset in qcow2
- * file. If the offset is not found, allocate a new cluster.
+ * Note that offset may not be cluster aligned. In this case, the returned
+ * *host_offset points to exact byte referenced by offset and therefore
+ * isn't cluster aligned as well.
*
- * If the cluster was already allocated, m->nb_clusters is set to 0 and
- * other fields in m are meaningless.
+ * On return, @host_offset is set to the beginning of the requested
+ * area. This area is guaranteed to be contiguous on the qcow2 file
+ * but it can be smaller than initially requested. In this case @bytes
+ * is updated with the actual size.
*
- * If the cluster is newly allocated, m->nb_clusters is set to the number of
- * contiguous clusters that have been allocated. In this case, the other
- * fields of m are valid and contain information about the first allocated
- * cluster.
+ * If any clusters or subclusters were allocated then @m contains a
+ * list with the information of all the affected regions. Note that
+ * this can happen regardless of whether this function succeeds or
+ * not. The caller is responsible for updating the L2 metadata of the
+ * allocated clusters (on success) or freeing them (on failure), and
+ * for clearing the contents of @m afterwards in both cases.
*
* If the request conflicts with another write request in flight, the coroutine
* is queued and will be reentered when the dependency has completed.
*
* Return 0 on success and -errno in error cases
*/
-int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
- unsigned int *bytes, uint64_t *host_offset,
- QCowL2Meta **m)
+int qcow2_alloc_host_offset(BlockDriverState *bs, uint64_t offset,
+ unsigned int *bytes, uint64_t *host_offset,
+ QCowL2Meta **m)
{
BDRVQcow2State *s = bs->opaque;
uint64_t start, remaining;
while (true) {
if (*host_offset == INV_OFFSET && cluster_offset != INV_OFFSET) {
- *host_offset = start_of_cluster(s, cluster_offset);
+ *host_offset = cluster_offset;
}
assert(remaining >= cur_bytes);
*bytes -= remaining;
assert(*bytes > 0);
assert(*host_offset != INV_OFFSET);
+ assert(offset_into_cluster(s, *host_offset) ==
+ offset_into_cluster(s, offset));
return 0;
}
assert(nb_clusters <= INT_MAX);
for (i = 0; i < nb_clusters; i++) {
- uint64_t old_l2_entry;
-
- old_l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
+ uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ uint64_t new_l2_entry = old_l2_entry;
+ uint64_t new_l2_bitmap = old_l2_bitmap;
+ QCow2ClusterType cluster_type =
+ qcow2_get_cluster_type(bs, old_l2_entry);
/*
+ * If full_discard is true, the cluster should not read back as zeroes,
+ * but rather fall through to the backing file.
+ *
* If full_discard is false, make sure that a discarded area reads back
* as zeroes for v3 images (we cannot do it for v2 without actually
* writing a zero-filled buffer). We can skip the operation if the
*
* TODO We might want to use bdrv_block_status(bs) here, but we're
* holding s->lock, so that doesn't work today.
- *
- * If full_discard is true, the sector should not read back as zeroes,
- * but rather fall through to the backing file.
*/
- switch (qcow2_get_cluster_type(bs, old_l2_entry)) {
- case QCOW2_CLUSTER_UNALLOCATED:
- if (full_discard || !bs->backing) {
- continue;
- }
- break;
-
- case QCOW2_CLUSTER_ZERO_PLAIN:
- if (!full_discard) {
- continue;
+ if (full_discard) {
+ new_l2_entry = new_l2_bitmap = 0;
+ } else if (bs->backing || qcow2_cluster_is_allocated(cluster_type)) {
+ if (has_subclusters(s)) {
+ new_l2_entry = 0;
+ new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES;
+ } else {
+ new_l2_entry = s->qcow_version >= 3 ? QCOW_OFLAG_ZERO : 0;
}
- break;
-
- case QCOW2_CLUSTER_ZERO_ALLOC:
- case QCOW2_CLUSTER_NORMAL:
- case QCOW2_CLUSTER_COMPRESSED:
- break;
+ }
- default:
- abort();
+ if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) {
+ continue;
}
/* First remove L2 entries */
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
- if (!full_discard && s->qcow_version >= 3) {
- l2_slice[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
- } else {
- l2_slice[l2_index + i] = cpu_to_be64(0);
+ set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry);
+ if (has_subclusters(s)) {
+ set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap);
}
-
/* Then decrease the refcount */
- qcow2_free_any_clusters(bs, old_l2_entry, 1, type);
+ qcow2_free_any_cluster(bs, old_l2_entry, type);
}
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
int l2_index;
int ret;
int i;
- bool unmap = !!(flags & BDRV_REQ_MAY_UNMAP);
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
if (ret < 0) {
assert(nb_clusters <= INT_MAX);
for (i = 0; i < nb_clusters; i++) {
- uint64_t old_offset;
- QCow2ClusterType cluster_type;
-
- old_offset = be64_to_cpu(l2_slice[l2_index + i]);
+ uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ QCow2ClusterType type = qcow2_get_cluster_type(bs, old_l2_entry);
+ bool unmap = (type == QCOW2_CLUSTER_COMPRESSED) ||
+ ((flags & BDRV_REQ_MAY_UNMAP) && qcow2_cluster_is_allocated(type));
+ uint64_t new_l2_entry = unmap ? 0 : old_l2_entry;
+ uint64_t new_l2_bitmap = old_l2_bitmap;
+
+ if (has_subclusters(s)) {
+ new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES;
+ } else {
+ new_l2_entry |= QCOW_OFLAG_ZERO;
+ }
- /*
- * Minimize L2 changes if the cluster already reads back as
- * zeroes with correct allocation.
- */
- cluster_type = qcow2_get_cluster_type(bs, old_offset);
- if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN ||
- (cluster_type == QCOW2_CLUSTER_ZERO_ALLOC && !unmap)) {
+ if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) {
continue;
}
+ /* First update L2 entries */
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
- if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) {
- l2_slice[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
- qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
- } else {
- l2_slice[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
+ set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry);
+ if (has_subclusters(s)) {
+ set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap);
+ }
+
+ /* Then decrease the refcount */
+ if (unmap) {
+ qcow2_free_any_cluster(bs, old_l2_entry, QCOW2_DISCARD_REQUEST);
}
}
return nb_clusters;
}
-int qcow2_cluster_zeroize(BlockDriverState *bs, uint64_t offset,
- uint64_t bytes, int flags)
+static int zero_l2_subclusters(BlockDriverState *bs, uint64_t offset,
+ unsigned nb_subclusters)
+{
+ BDRVQcow2State *s = bs->opaque;
+ uint64_t *l2_slice;
+ uint64_t old_l2_bitmap, l2_bitmap;
+ int l2_index, ret, sc = offset_to_sc_index(s, offset);
+
+ /* For full clusters use zero_in_l2_slice() instead */
+ assert(nb_subclusters > 0 && nb_subclusters < s->subclusters_per_cluster);
+ assert(sc + nb_subclusters <= s->subclusters_per_cluster);
+ assert(offset_into_subcluster(s, offset) == 0);
+
+ ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
+ if (ret < 0) {
+ return ret;
+ }
+
+ switch (qcow2_get_cluster_type(bs, get_l2_entry(s, l2_slice, l2_index))) {
+ case QCOW2_CLUSTER_COMPRESSED:
+ ret = -ENOTSUP; /* We cannot partially zeroize compressed clusters */
+ goto out;
+ case QCOW2_CLUSTER_NORMAL:
+ case QCOW2_CLUSTER_UNALLOCATED:
+ break;
+ default:
+ g_assert_not_reached();
+ }
+
+ old_l2_bitmap = l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
+
+ l2_bitmap |= QCOW_OFLAG_SUB_ZERO_RANGE(sc, sc + nb_subclusters);
+ l2_bitmap &= ~QCOW_OFLAG_SUB_ALLOC_RANGE(sc, sc + nb_subclusters);
+
+ if (old_l2_bitmap != l2_bitmap) {
+ set_l2_bitmap(s, l2_slice, l2_index, l2_bitmap);
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
+ }
+
+ ret = 0;
+out:
+ qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
+
+ return ret;
+}
+
+int qcow2_subcluster_zeroize(BlockDriverState *bs, uint64_t offset,
+ uint64_t bytes, int flags)
{
BDRVQcow2State *s = bs->opaque;
uint64_t end_offset = offset + bytes;
uint64_t nb_clusters;
+ unsigned head, tail;
int64_t cleared;
int ret;
}
/* Caller must pass aligned values, except at image end */
- assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
- assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) ||
+ assert(offset_into_subcluster(s, offset) == 0);
+ assert(offset_into_subcluster(s, end_offset) == 0 ||
end_offset >= bs->total_sectors << BDRV_SECTOR_BITS);
/*
return -ENOTSUP;
}
- /* Each L2 slice is handled by its own loop iteration */
- nb_clusters = size_to_clusters(s, bytes);
+ head = MIN(end_offset, ROUND_UP(offset, s->cluster_size)) - offset;
+ offset += head;
+
+ tail = (end_offset >= bs->total_sectors << BDRV_SECTOR_BITS) ? 0 :
+ end_offset - MAX(offset, start_of_cluster(s, end_offset));
+ end_offset -= tail;
s->cache_discards = true;
+ if (head) {
+ ret = zero_l2_subclusters(bs, offset - head,
+ size_to_subclusters(s, head));
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+
+ /* Each L2 slice is handled by its own loop iteration */
+ nb_clusters = size_to_clusters(s, end_offset - offset);
+
while (nb_clusters > 0) {
cleared = zero_in_l2_slice(bs, offset, nb_clusters, flags);
if (cleared < 0) {
offset += (cleared * s->cluster_size);
}
+ if (tail) {
+ ret = zero_l2_subclusters(bs, end_offset, size_to_subclusters(s, tail));
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+
ret = 0;
fail:
s->cache_discards = false;
int ret;
int i, j;
- slice_size2 = s->l2_slice_size * sizeof(uint64_t);
+ /* qcow2_downgrade() is not allowed in images with subclusters */
+ assert(!has_subclusters(s));
+
+ slice_size2 = s->l2_slice_size * l2_entry_size(s);
n_slices = s->cluster_size / slice_size2;
if (!is_active_l1) {
}
for (j = 0; j < s->l2_slice_size; j++) {
- uint64_t l2_entry = be64_to_cpu(l2_slice[j]);
+ uint64_t l2_entry = get_l2_entry(s, l2_slice, j);
int64_t offset = l2_entry & L2E_OFFSET_MASK;
QCow2ClusterType cluster_type =
qcow2_get_cluster_type(bs, l2_entry);
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
if (!bs->backing) {
- /* not backed; therefore we can simply deallocate the
- * cluster */
- l2_slice[j] = 0;
+ /*
+ * not backed; therefore we can simply deallocate the
+ * cluster. No need to call set_l2_bitmap(), this
+ * function doesn't support images with subclusters.
+ */
+ set_l2_entry(s, l2_slice, j, 0);
l2_dirty = true;
continue;
}
}
if (l2_refcount == 1) {
- l2_slice[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED);
+ set_l2_entry(s, l2_slice, j, offset | QCOW_OFLAG_COPIED);
} else {
- l2_slice[j] = cpu_to_be64(offset);
+ set_l2_entry(s, l2_slice, j, offset);
}
+ /*
+ * No need to call set_l2_bitmap() after set_l2_entry() because
+ * this function doesn't support images with subclusters.
+ */
l2_dirty = true;
}
Error *local_err = NULL;
ret = qcow2_validate_table(bs, s->snapshots[i].l1_table_offset,
- s->snapshots[i].l1_size, sizeof(uint64_t),
+ s->snapshots[i].l1_size, L1E_SIZE,
QCOW_MAX_L1_SIZE, "Snapshot L1 table",
&local_err);
if (ret < 0) {
goto fail;
}
- l1_size2 = s->snapshots[i].l1_size * sizeof(uint64_t);
+ l1_size2 = s->snapshots[i].l1_size * L1E_SIZE;
new_l1_table = g_try_realloc(l1_table, l1_size2);
if (!new_l1_table) {
g_free(l1_table);
return ret;
}
+
+void qcow2_parse_compressed_l2_entry(BlockDriverState *bs, uint64_t l2_entry,
+ uint64_t *coffset, int *csize)
+{
+ BDRVQcow2State *s = bs->opaque;
+ int nb_csectors;
+
+ assert(qcow2_get_cluster_type(bs, l2_entry) == QCOW2_CLUSTER_COMPRESSED);
+
+ *coffset = l2_entry & s->cluster_offset_mask;
+
+ nb_csectors = ((l2_entry >> s->csize_shift) & s->csize_mask) + 1;
+ *csize = nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE -
+ (*coffset & (QCOW2_COMPRESSED_SECTOR_SIZE - 1));
+}
projects / qemu.git / blobdiff