#include <zlib.h>
#include "qemu-common.h"
-#include "block_int.h"
+#include "block/block_int.h"
#include "block/qcow2.h"
#include "trace.h"
-int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size)
+int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
+ bool exact_size)
{
BDRVQcowState *s = bs->opaque;
- int new_l1_size, new_l1_size2, ret, i;
+ int new_l1_size2, ret, i;
uint64_t *new_l1_table;
- int64_t new_l1_table_offset;
+ int64_t new_l1_table_offset, new_l1_size;
uint8_t data[12];
if (min_size <= s->l1_size)
}
}
+ if (new_l1_size > INT_MAX) {
+ return -EFBIG;
+ }
+
#ifdef DEBUG_ALLOC2
- fprintf(stderr, "grow l1_table from %d to %d\n", s->l1_size, new_l1_size);
+ fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n",
+ s->l1_size, new_l1_size);
#endif
new_l1_size2 = sizeof(uint64_t) * new_l1_size;
goto fail;
}
+ /* the L1 position has not yet been updated, so these clusters must
+ * indeed be completely free */
+ ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
+ new_l1_table_offset, new_l1_size2);
+ if (ret < 0) {
+ goto fail;
+ }
+
BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE);
for(i = 0; i < s->l1_size; i++)
new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
goto fail;
}
g_free(s->l1_table);
- qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t));
+ qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t),
+ QCOW2_DISCARD_OTHER);
s->l1_table_offset = new_l1_table_offset;
s->l1_table = new_l1_table;
s->l1_size = new_l1_size;
return 0;
fail:
g_free(new_l1_table);
- qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2);
+ qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
+ QCOW2_DISCARD_OTHER);
return ret;
}
* and we really don't want bdrv_pread to perform a read-modify-write)
*/
#define L1_ENTRIES_PER_SECTOR (512 / 8)
-static int write_l1_entry(BlockDriverState *bs, int l1_index)
+int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
{
BDRVQcowState *s = bs->opaque;
uint64_t buf[L1_ENTRIES_PER_SECTOR];
buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
}
+ ret = qcow2_pre_write_overlap_check(bs,
+ QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L1,
+ s->l1_table_offset + 8 * l1_start_index, sizeof(buf));
+ 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,
buf, sizeof(buf));
/* update the L1 entry */
trace_qcow2_l2_allocate_write_l1(bs, l1_index);
s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
- ret = write_l1_entry(bs, l1_index);
+ ret = qcow2_write_l1_entry(bs, l1_index);
if (ret < 0) {
goto fail;
}
&s->aes_encrypt_key);
}
+ ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
+ cluster_offset + n_start * BDRV_SECTOR_SIZE, n * BDRV_SECTOR_SIZE);
+ if (ret < 0) {
+ goto out;
+ }
+
BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + n_start, n, &qiov);
if (ret < 0) {
int *num, uint64_t *cluster_offset)
{
BDRVQcowState *s = bs->opaque;
- unsigned int l1_index, l2_index;
- uint64_t l2_offset, *l2_table;
+ unsigned int l2_index;
+ uint64_t l1_index, l2_offset, *l2_table;
int l1_bits, c;
unsigned int index_in_cluster, nb_clusters;
uint64_t nb_available, nb_needed;
*cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
break;
case QCOW2_CLUSTER_ZERO:
+ if (s->qcow_version < 3) {
+ return -EIO;
+ }
c = count_contiguous_clusters(nb_clusters, s->cluster_size,
&l2_table[l2_index], 0,
QCOW_OFLAG_COMPRESSED | QCOW_OFLAG_ZERO);
QCOW_OFLAG_COMPRESSED | QCOW_OFLAG_ZERO);
*cluster_offset &= L2E_OFFSET_MASK;
break;
+ default:
+ abort();
}
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
int *new_l2_index)
{
BDRVQcowState *s = bs->opaque;
- unsigned int l1_index, l2_index;
- uint64_t l2_offset;
+ unsigned int l2_index;
+ uint64_t l1_index, l2_offset;
uint64_t *l2_table = NULL;
int ret;
}
}
+ assert(l1_index < s->l1_size);
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
/* seek the l2 table of the given l2 offset */
/* 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 * sizeof(uint64_t),
+ QCOW2_DISCARD_OTHER);
}
- l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
}
/* find the cluster offset for the given disk offset */
return cluster_offset;
}
-int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
+static int perform_cow(BlockDriverState *bs, QCowL2Meta *m, Qcow2COWRegion *r)
{
BDRVQcowState *s = bs->opaque;
- int i, j = 0, l2_index, ret;
- uint64_t *old_cluster, start_sect, *l2_table;
- uint64_t cluster_offset = m->alloc_offset;
- bool cow = false;
-
- trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
+ int ret;
- if (m->nb_clusters == 0)
+ if (r->nb_sectors == 0) {
return 0;
+ }
- old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
+ qemu_co_mutex_unlock(&s->lock);
+ ret = copy_sectors(bs, m->offset / BDRV_SECTOR_SIZE, m->alloc_offset,
+ r->offset / BDRV_SECTOR_SIZE,
+ r->offset / BDRV_SECTOR_SIZE + r->nb_sectors);
+ qemu_co_mutex_lock(&s->lock);
- /* copy content of unmodified sectors */
- start_sect = (m->offset & ~(s->cluster_size - 1)) >> 9;
- if (m->n_start) {
- cow = true;
- qemu_co_mutex_unlock(&s->lock);
- ret = copy_sectors(bs, start_sect, cluster_offset, 0, m->n_start);
- qemu_co_mutex_lock(&s->lock);
- if (ret < 0)
- goto err;
- }
-
- if (m->nb_available & (s->cluster_sectors - 1)) {
- uint64_t end = m->nb_available & ~(uint64_t)(s->cluster_sectors - 1);
- cow = true;
- qemu_co_mutex_unlock(&s->lock);
- ret = copy_sectors(bs, start_sect + end, cluster_offset + (end << 9),
- m->nb_available - end, s->cluster_sectors);
- qemu_co_mutex_lock(&s->lock);
- if (ret < 0)
- goto err;
+ if (ret < 0) {
+ return ret;
}
/*
- * Update L2 table.
- *
* Before we update the L2 table to actually point to the new cluster, we
* need to be sure that the refcounts have been increased and COW was
* handled.
*/
- if (cow) {
- qcow2_cache_depends_on_flush(s->l2_table_cache);
+ qcow2_cache_depends_on_flush(s->l2_table_cache);
+
+ return 0;
+}
+
+int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
+{
+ BDRVQcowState *s = bs->opaque;
+ int i, j = 0, l2_index, ret;
+ uint64_t *old_cluster, *l2_table;
+ uint64_t cluster_offset = m->alloc_offset;
+
+ trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
+ assert(m->nb_clusters > 0);
+
+ old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
+
+ /* copy content of unmodified sectors */
+ ret = perform_cow(bs, m, &m->cow_start);
+ if (ret < 0) {
+ goto err;
+ }
+
+ ret = perform_cow(bs, m, &m->cow_end);
+ if (ret < 0) {
+ goto err;
+ }
+
+ /* Update L2 table. */
+ if (s->use_lazy_refcounts) {
+ qcow2_mark_dirty(bs);
+ }
+ if (qcow2_need_accurate_refcounts(s)) {
+ qcow2_cache_set_dependency(bs, s->l2_table_cache,
+ s->refcount_block_cache);
}
- qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache);
ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index);
if (ret < 0) {
goto err;
/*
* If this was a COW, we need to decrease the refcount of the old cluster.
* Also flush bs->file to get the right order for L2 and refcount update.
+ *
+ * Don't discard clusters that reach a refcount of 0 (e.g. compressed
+ * clusters), the next write will reuse them anyway.
*/
if (j != 0) {
for (i = 0; i < j; i++) {
- qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1);
+ qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
+ QCOW2_DISCARD_NEVER);
}
}
}
/*
- * Allocates new clusters for the given guest_offset.
+ * Check if there already is an AIO write request in flight which allocates
+ * the same cluster. In this case we need to wait until the previous
+ * request has completed and updated the L2 table accordingly.
*
- * At most *nb_clusters are allocated, and on return *nb_clusters is updated to
- * contain the number of clusters that have been allocated and are contiguous
- * in the image file.
- *
- * If *host_offset is non-zero, it specifies the offset in the image file at
- * which the new clusters must start. *nb_clusters can be 0 on return in this
- * case if the cluster at host_offset is already in use. If *host_offset is
- * zero, the clusters can be allocated anywhere in the image file.
- *
- * *host_offset is updated to contain the offset into the image file at which
- * the first allocated cluster starts.
+ * Returns:
+ * 0 if there was no dependency. *cur_bytes indicates the number of
+ * bytes from guest_offset that can be read before the next
+ * dependency must be processed (or the request is complete)
*
- * Return 0 on success and -errno in error cases. -EAGAIN means that the
- * function has been waiting for another request and the allocation must be
- * restarted, but the whole request should not be failed.
+ * -EAGAIN if we had to wait for another request, previously gathered
+ * information on cluster allocation may be invalid now. The caller
+ * must start over anyway, so consider *cur_bytes undefined.
*/
-static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
- uint64_t *host_offset, unsigned int *nb_clusters)
+static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
+ uint64_t *cur_bytes, QCowL2Meta **m)
{
BDRVQcowState *s = bs->opaque;
- int64_t cluster_offset;
QCowL2Meta *old_alloc;
+ uint64_t bytes = *cur_bytes;
- trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
- *host_offset, *nb_clusters);
-
- /*
- * Check if there already is an AIO write request in flight which allocates
- * the same cluster. In this case we need to wait until the previous
- * request has completed and updated the L2 table accordingly.
- */
QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
- uint64_t start = guest_offset >> s->cluster_bits;
- uint64_t end = start + *nb_clusters;
- uint64_t old_start = old_alloc->offset >> s->cluster_bits;
- uint64_t old_end = old_start + old_alloc->nb_clusters;
+ 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);
- if (end < old_start || start > old_end) {
+ if (end <= old_start || start >= old_end) {
/* No intersection */
} else {
if (start < old_start) {
/* Stop at the start of a running allocation */
- *nb_clusters = old_start - start;
+ bytes = old_start - start;
} else {
- *nb_clusters = 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;
}
- if (*nb_clusters == 0) {
+ if (bytes == 0) {
/* Wait for the dependency to complete. We need to recheck
* the free/allocated clusters when we continue. */
qemu_co_mutex_unlock(&s->lock);
}
}
- if (!*nb_clusters) {
- abort();
- }
+ /* Make sure that existing clusters and new allocations are only used up to
+ * the next dependency if we shortened the request above */
+ *cur_bytes = bytes;
- /* Allocate new clusters */
- trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
- if (*host_offset == 0) {
- cluster_offset = qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size);
- } else {
- cluster_offset = *host_offset;
- *nb_clusters = qcow2_alloc_clusters_at(bs, cluster_offset, *nb_clusters);
- }
-
- if (cluster_offset < 0) {
- return cluster_offset;
- }
- *host_offset = cluster_offset;
return 0;
}
/*
- * alloc_cluster_offset
+ * 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 zero, only physically contiguous clusters beginning at
+ * this host offset are counted.
*
- * 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 guest_offset may not be cluster aligned. In this case, the
+ * returned *host_offset points to exact byte referenced by guest_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.
+ * 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.
*
- * 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.
+ * 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.
*
- * 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
+ * -errno: in error cases
*/
-int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
- int n_start, int n_end, int *num, QCowL2Meta *m)
+static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
+ uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
{
BDRVQcowState *s = bs->opaque;
- int l2_index, ret, sectors;
- uint64_t *l2_table;
- unsigned int nb_clusters, keep_clusters;
+ int l2_index;
uint64_t cluster_offset;
+ uint64_t *l2_table;
+ unsigned int nb_clusters;
+ unsigned int keep_clusters;
+ int ret, pret;
- trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset,
- n_start, n_end);
+ trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset,
+ *bytes);
- /* Find L2 entry for the first involved cluster */
-again:
- ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
- if (ret < 0) {
- return ret;
- }
+ assert(*host_offset == 0 || offset_into_cluster(s, guest_offset)
+ == offset_into_cluster(s, *host_offset));
/*
* Calculate the number of clusters to look for. We stop at L2 table
* boundaries to keep things simple.
*/
- nb_clusters = MIN(size_to_clusters(s, n_end << BDRV_SECTOR_BITS),
- s->l2_size - l2_index);
+ nb_clusters =
+ size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
+
+ l2_index = offset_to_l2_index(s, guest_offset);
+ nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+
+ /* Find L2 entry for the first involved cluster */
+ ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
+ if (ret < 0) {
+ return ret;
+ }
cluster_offset = be64_to_cpu(l2_table[l2_index]);
- /*
- * Check how many clusters are already allocated and don't need COW, and how
- * many need a new allocation.
- */
+ /* Check how many clusters are already allocated and don't need COW */
if (qcow2_get_cluster_type(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 (*host_offset != 0 && !offset_matches) {
+ *bytes = 0;
+ ret = 0;
+ goto out;
+ }
+
/* We keep all QCOW_OFLAG_COPIED clusters */
keep_clusters =
count_contiguous_clusters(nb_clusters, s->cluster_size,
&l2_table[l2_index], 0,
QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO);
assert(keep_clusters <= nb_clusters);
- nb_clusters -= keep_clusters;
+
+ *bytes = MIN(*bytes,
+ keep_clusters * s->cluster_size
+ - offset_into_cluster(s, guest_offset));
+
+ ret = 1;
} else {
- keep_clusters = 0;
- cluster_offset = 0;
+ ret = 0;
}
- if (nb_clusters > 0) {
- /* For the moment, overwrite compressed clusters one by one */
- uint64_t entry = be64_to_cpu(l2_table[l2_index + keep_clusters]);
- if (entry & QCOW_OFLAG_COMPRESSED) {
- nb_clusters = 1;
- } else {
- nb_clusters = count_cow_clusters(s, nb_clusters, l2_table,
- l2_index + keep_clusters);
+ /* Cleanup */
+out:
+ pret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+ if (pret < 0) {
+ return pret;
+ }
+
+ /* 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) {
+ *host_offset = (cluster_offset & L2E_OFFSET_MASK)
+ + offset_into_cluster(s, guest_offset);
+ }
+
+ return ret;
+}
+
+/*
+ * Allocates new clusters for the given guest_offset.
+ *
+ * At most *nb_clusters are allocated, and on return *nb_clusters is updated to
+ * contain the number of clusters that have been allocated and are contiguous
+ * in the image file.
+ *
+ * If *host_offset is non-zero, it specifies the offset in the image file at
+ * which the new clusters must start. *nb_clusters can be 0 on return in this
+ * case if the cluster at host_offset is already in use. If *host_offset is
+ * zero, the clusters can be allocated anywhere in the image file.
+ *
+ * *host_offset is updated to contain the offset into the image file at which
+ * the first allocated cluster starts.
+ *
+ * Return 0 on success and -errno in error cases. -EAGAIN means that the
+ * function has been waiting for another request and the allocation must be
+ * restarted, but the whole request should not be failed.
+ */
+static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
+ uint64_t *host_offset, unsigned int *nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+
+ trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
+ *host_offset, *nb_clusters);
+
+ /* Allocate new clusters */
+ trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
+ if (*host_offset == 0) {
+ int64_t cluster_offset =
+ qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size);
+ if (cluster_offset < 0) {
+ return cluster_offset;
}
+ *host_offset = cluster_offset;
+ return 0;
+ } else {
+ int ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
+ if (ret < 0) {
+ return ret;
+ }
+ *nb_clusters = ret;
+ return 0;
}
+}
+
+/*
+ * Allocates new clusters for an area that either is yet unallocated or needs a
+ * copy on write. If *host_offset is non-zero, 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
+ * therefore isn't cluster aligned as well.
+ *
+ * Returns:
+ * 0: if no clusters could be allocated. *bytes is set to 0,
+ * *host_offset is left unchanged.
+ *
+ * 1: if new clusters were allocated. *bytes may be decreased if the
+ * new allocation doesn't cover all of the requested area.
+ * *host_offset is updated to contain the host offset of the first
+ * newly allocated cluster.
+ *
+ * -errno: in error cases
+ */
+static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
+ uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
+{
+ BDRVQcowState *s = bs->opaque;
+ int l2_index;
+ uint64_t *l2_table;
+ uint64_t entry;
+ unsigned int nb_clusters;
+ int ret;
- cluster_offset &= L2E_OFFSET_MASK;
+ uint64_t alloc_cluster_offset;
+
+ trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset,
+ *bytes);
+ assert(*bytes > 0);
/*
- * The L2 table isn't used any more after this. As long as the cache works
- * synchronously, it's important to release it before calling
- * do_alloc_cluster_offset, which may yield if we need to wait for another
- * request to complete. If we still had the reference, we could use up the
- * whole cache with sleeping requests.
+ * Calculate the number of clusters to look for. We stop at L2 table
+ * boundaries to keep things simple.
*/
+ nb_clusters =
+ size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
+
+ l2_index = offset_to_l2_index(s, guest_offset);
+ nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+
+ /* Find L2 entry for the first involved cluster */
+ ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
+ if (ret < 0) {
+ return ret;
+ }
+
+ entry = be64_to_cpu(l2_table[l2_index]);
+
+ /* For the moment, overwrite compressed clusters one by one */
+ if (entry & QCOW_OFLAG_COMPRESSED) {
+ nb_clusters = 1;
+ } else {
+ nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, l2_index);
+ }
+
+ /* 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);
+
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
if (ret < 0) {
return ret;
}
- /* If there is something left to allocate, do that now */
- *m = (QCowL2Meta) {
- .cluster_offset = cluster_offset,
- .nb_clusters = 0,
+ /* Allocate, if necessary at a given offset in the image file */
+ alloc_cluster_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;
+ }
+
+ /*
+ * Save info needed for meta data update.
+ *
+ * requested_sectors: Number of sectors from the start of the first
+ * newly allocated cluster to the end of the (possibly shortened
+ * before) write request.
+ *
+ * avail_sectors: Number of sectors from the start of the first
+ * newly allocated to the end of the last newly allocated cluster.
+ *
+ * nb_sectors: The number of sectors from the start of the first
+ * newly allocated cluster to the end of the area that the write
+ * request actually writes to (excluding COW at the end)
+ */
+ int requested_sectors =
+ (*bytes + offset_into_cluster(s, guest_offset))
+ >> BDRV_SECTOR_BITS;
+ int avail_sectors = nb_clusters
+ << (s->cluster_bits - BDRV_SECTOR_BITS);
+ int alloc_n_start = offset_into_cluster(s, guest_offset)
+ >> BDRV_SECTOR_BITS;
+ int nb_sectors = MIN(requested_sectors, avail_sectors);
+ 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,
+ .nb_available = nb_sectors,
+
+ .cow_start = {
+ .offset = 0,
+ .nb_sectors = alloc_n_start,
+ },
+ .cow_end = {
+ .offset = nb_sectors * BDRV_SECTOR_SIZE,
+ .nb_sectors = avail_sectors - nb_sectors,
+ },
};
- qemu_co_queue_init(&m->dependent_requests);
+ qemu_co_queue_init(&(*m)->dependent_requests);
+ QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
- if (nb_clusters > 0) {
- uint64_t alloc_offset;
- uint64_t alloc_cluster_offset;
- uint64_t keep_bytes = keep_clusters * s->cluster_size;
+ *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
+ *bytes = MIN(*bytes, (nb_sectors * BDRV_SECTOR_SIZE)
+ - offset_into_cluster(s, guest_offset));
+ assert(*bytes != 0);
- /* Calculate start and size of allocation */
- alloc_offset = offset + keep_bytes;
+ return 1;
- if (keep_clusters == 0) {
- alloc_cluster_offset = 0;
- } else {
- alloc_cluster_offset = cluster_offset + keep_bytes;
+fail:
+ if (*m && (*m)->nb_clusters > 0) {
+ QLIST_REMOVE(*m, next_in_flight);
+ }
+ return ret;
+}
+
+/*
+ * alloc_cluster_offset
+ *
+ * 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.
+ *
+ * If the cluster was already allocated, m->nb_clusters is set to 0 and
+ * other fields in m are meaningless.
+ *
+ * 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 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,
+ int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t start, remaining;
+ uint64_t cluster_offset;
+ uint64_t cur_bytes;
+ int ret;
+
+ trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset,
+ n_start, n_end);
+
+ assert(n_start * BDRV_SECTOR_SIZE == offset_into_cluster(s, offset));
+ offset = start_of_cluster(s, offset);
+
+again:
+ start = offset + (n_start << BDRV_SECTOR_BITS);
+ remaining = (n_end - n_start) << BDRV_SECTOR_BITS;
+ cluster_offset = 0;
+ *host_offset = 0;
+ cur_bytes = 0;
+ *m = NULL;
+
+ while (true) {
+
+ if (!*host_offset) {
+ *host_offset = start_of_cluster(s, cluster_offset);
+ }
+
+ assert(remaining >= cur_bytes);
+
+ start += cur_bytes;
+ remaining -= cur_bytes;
+ cluster_offset += cur_bytes;
+
+ if (remaining == 0) {
+ break;
}
- /* Allocate, if necessary at a given offset in the image file */
- ret = do_alloc_cluster_offset(bs, alloc_offset, &alloc_cluster_offset,
- &nb_clusters);
+ cur_bytes = remaining;
+
+ /*
+ * Now start gathering as many contiguous clusters as possible:
+ *
+ * 1. Check for overlaps with in-flight allocations
+ *
+ * a) Overlap not in the first cluster -> shorten this request and
+ * let the caller handle the rest in its next loop iteration.
+ *
+ * b) Real overlaps of two requests. Yield and restart the search
+ * for contiguous clusters (the situation could have changed
+ * while we were sleeping)
+ *
+ * c) TODO: Request starts in the same cluster as the in-flight
+ * allocation ends. Shorten the COW of the in-fight allocation,
+ * set cluster_offset to write to the same cluster and set up
+ * the right synchronisation between the in-flight request and
+ * the new one.
+ */
+ ret = handle_dependencies(bs, start, &cur_bytes, m);
if (ret == -EAGAIN) {
+ /* Currently handle_dependencies() doesn't yield if we already had
+ * an allocation. If it did, we would have to clean up the L2Meta
+ * structs before starting over. */
+ assert(*m == NULL);
goto again;
} else if (ret < 0) {
- goto fail;
+ return ret;
+ } else if (cur_bytes == 0) {
+ break;
+ } else {
+ /* handle_dependencies() may have decreased cur_bytes (shortened
+ * the allocations below) so that the next dependency is processed
+ * correctly during the next loop iteration. */
}
- /* save info needed for meta data update */
- if (nb_clusters > 0) {
- int requested_sectors = n_end - keep_clusters * s->cluster_sectors;
- int avail_sectors = (keep_clusters + nb_clusters)
- << (s->cluster_bits - BDRV_SECTOR_BITS);
-
- *m = (QCowL2Meta) {
- .cluster_offset = keep_clusters == 0 ?
- alloc_cluster_offset : cluster_offset,
- .alloc_offset = alloc_cluster_offset,
- .offset = alloc_offset,
- .n_start = keep_clusters == 0 ? n_start : 0,
- .nb_clusters = nb_clusters,
- .nb_available = MIN(requested_sectors, avail_sectors),
- };
- qemu_co_queue_init(&m->dependent_requests);
- QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight);
+ /*
+ * 2. Count contiguous COPIED clusters.
+ */
+ ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m);
+ if (ret < 0) {
+ return ret;
+ } else if (ret) {
+ continue;
+ } else if (cur_bytes == 0) {
+ break;
}
- }
- /* Some cleanup work */
- sectors = (keep_clusters + nb_clusters) << (s->cluster_bits - 9);
- if (sectors > n_end) {
- sectors = n_end;
+ /*
+ * 3. If the request still hasn't completed, allocate new clusters,
+ * considering any cluster_offset of steps 1c or 2.
+ */
+ ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m);
+ if (ret < 0) {
+ return ret;
+ } else if (ret) {
+ continue;
+ } else {
+ assert(cur_bytes == 0);
+ break;
+ }
}
- assert(sectors > n_start);
- *num = sectors - n_start;
+ *num = (n_end - n_start) - (remaining >> BDRV_SECTOR_BITS);
+ assert(*num > 0);
+ assert(*host_offset != 0);
return 0;
-
-fail:
- if (m->nb_clusters > 0) {
- QLIST_REMOVE(m, next_in_flight);
- }
- return ret;
}
static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
* clusters.
*/
static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
- unsigned int nb_clusters)
+ unsigned int nb_clusters, enum qcow2_discard_type type)
{
BDRVQcowState *s = bs->opaque;
uint64_t *l2_table;
l2_table[l2_index + i] = cpu_to_be64(0);
/* Then decrease the refcount */
- qcow2_free_any_clusters(bs, old_offset, 1);
+ qcow2_free_any_clusters(bs, old_offset, 1, type);
}
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
}
int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
- int nb_sectors)
+ int nb_sectors, enum qcow2_discard_type type)
{
BDRVQcowState *s = bs->opaque;
uint64_t end_offset;
nb_clusters = size_to_clusters(s, end_offset - offset);
+ s->cache_discards = true;
+
/* Each L2 table is handled by its own loop iteration */
while (nb_clusters > 0) {
- ret = discard_single_l2(bs, offset, nb_clusters);
+ ret = discard_single_l2(bs, offset, nb_clusters, type);
if (ret < 0) {
- return ret;
+ goto fail;
}
nb_clusters -= ret;
offset += (ret * s->cluster_size);
}
- return 0;
+ ret = 0;
+fail:
+ s->cache_discards = false;
+ qcow2_process_discards(bs, ret);
+
+ return ret;
}
/*
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
if (old_offset & QCOW_OFLAG_COMPRESSED) {
l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
- qcow2_free_any_clusters(bs, old_offset, 1);
+ qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
} else {
l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
}
/* Each L2 table is handled by its own loop iteration */
nb_clusters = size_to_clusters(s, nb_sectors << BDRV_SECTOR_BITS);
+ s->cache_discards = true;
+
while (nb_clusters > 0) {
ret = zero_single_l2(bs, offset, nb_clusters);
if (ret < 0) {
- return ret;
+ goto fail;
}
nb_clusters -= ret;
offset += (ret * s->cluster_size);
}
- return 0;
+ ret = 0;
+fail:
+ s->cache_discards = false;
+ qcow2_process_discards(bs, ret);
+
+ return ret;
}
projects / qemu.git / blobdiff