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/*
* QEMU Enhanced Disk Format Cluster functions
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qed.h"
/**
* Count the number of contiguous data clusters
*
* @s: QED state
* @table: L2 table
* @index: First cluster index
* @n: Maximum number of clusters
* @offset: Set to first cluster offset
*
* This function scans tables for contiguous allocated or free clusters.
*/
static unsigned int qed_count_contiguous_clusters(BDRVQEDState *s,
QEDTable *table,
unsigned int index,
unsigned int n,
uint64_t *offset)
{
unsigned int end = MIN(index + n, s->table_nelems);
uint64_t last = table->offsets[index];
unsigned int i;
*offset = last;
for (i = index + 1; i < end; i++) {
if (last == 0) {
/* Counting free clusters */
if (table->offsets[i] != 0) {
break;
}
} else {
/* Counting allocated clusters */
if (table->offsets[i] != last + s->header.cluster_size) {
break;
}
last = table->offsets[i];
}
}
return i - index;
}
typedef struct {
BDRVQEDState *s;
uint64_t pos;
size_t len;
QEDRequest *request;
/* User callback */
QEDFindClusterFunc *cb;
void *opaque;
} QEDFindClusterCB;
static void qed_find_cluster_cb(void *opaque, int ret)
{
QEDFindClusterCB *find_cluster_cb = opaque;
BDRVQEDState *s = find_cluster_cb->s;
QEDRequest *request = find_cluster_cb->request;
uint64_t offset = 0;
size_t len = 0;
unsigned int index;
unsigned int n;
if (ret) {
goto out;
}
index = qed_l2_index(s, find_cluster_cb->pos);
n = qed_bytes_to_clusters(s,
qed_offset_into_cluster(s, find_cluster_cb->pos) +
find_cluster_cb->len);
n = qed_count_contiguous_clusters(s, request->l2_table->table,
index, n, &offset);
ret = offset ? QED_CLUSTER_FOUND : QED_CLUSTER_L2;
len = MIN(find_cluster_cb->len, n * s->header.cluster_size -
qed_offset_into_cluster(s, find_cluster_cb->pos));
if (offset && !qed_check_cluster_offset(s, offset)) {
ret = -EINVAL;
}
out:
find_cluster_cb->cb(find_cluster_cb->opaque, ret, offset, len);
qemu_free(find_cluster_cb);
}
/**
* Find the offset of a data cluster
*
* @s: QED state
* @request: L2 cache entry
* @pos: Byte position in device
* @len: Number of bytes
* @cb: Completion function
* @opaque: User data for completion function
*
* This function translates a position in the block device to an offset in the
* image file. It invokes the cb completion callback to report back the
* translated offset or unallocated range in the image file.
*
* If the L2 table exists, request->l2_table points to the L2 table cache entry
* and the caller must free the reference when they are finished. The cache
* entry is exposed in this way to avoid callers having to read the L2 table
* again later during request processing. If request->l2_table is non-NULL it
* will be unreferenced before taking on the new cache entry.
*/
void qed_find_cluster(BDRVQEDState *s, QEDRequest *request, uint64_t pos,
size_t len, QEDFindClusterFunc *cb, void *opaque)
{
QEDFindClusterCB *find_cluster_cb;
uint64_t l2_offset;
/* Limit length to L2 boundary. Requests are broken up at the L2 boundary
* so that a request acts on one L2 table at a time.
*/
len = MIN(len, (((pos >> s->l1_shift) + 1) << s->l1_shift) - pos);
l2_offset = s->l1_table->offsets[qed_l1_index(s, pos)];
if (!l2_offset) {
cb(opaque, QED_CLUSTER_L1, 0, len);
return;
}
if (!qed_check_table_offset(s, l2_offset)) {
cb(opaque, -EINVAL, 0, 0);
return;
}
find_cluster_cb = qemu_malloc(sizeof(*find_cluster_cb));
find_cluster_cb->s = s;
find_cluster_cb->pos = pos;
find_cluster_cb->len = len;
find_cluster_cb->cb = cb;
find_cluster_cb->opaque = opaque;
find_cluster_cb->request = request;
qed_read_l2_table(s, request, l2_offset,
qed_find_cluster_cb, find_cluster_cb);
}
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