#include "qemu-common.h"
#include "block_int.h"
#include "block/qcow2.h"
+#include "trace.h"
-int qcow2_grow_l1_table(BlockDriverState *bs, int min_size)
+int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size)
{
BDRVQcowState *s = bs->opaque;
int new_l1_size, new_l1_size2, ret, i;
int64_t new_l1_table_offset;
uint8_t data[12];
- new_l1_size = s->l1_size;
- if (min_size <= new_l1_size)
+ if (min_size <= s->l1_size)
return 0;
- if (new_l1_size == 0) {
- new_l1_size = 1;
- }
- while (min_size > new_l1_size) {
- new_l1_size = (new_l1_size * 3 + 1) / 2;
+
+ if (exact_size) {
+ new_l1_size = min_size;
+ } else {
+ /* Bump size up to reduce the number of times we have to grow */
+ new_l1_size = s->l1_size;
+ if (new_l1_size == 0) {
+ new_l1_size = 1;
+ }
+ while (min_size > new_l1_size) {
+ new_l1_size = (new_l1_size * 3 + 1) / 2;
+ }
}
+
#ifdef DEBUG_ALLOC2
- printf("grow l1_table from %d to %d\n", s->l1_size, new_l1_size);
+ fprintf(stderr, "grow l1_table from %d to %d\n", s->l1_size, new_l1_size);
#endif
new_l1_size2 = sizeof(uint64_t) * new_l1_size;
- new_l1_table = qemu_mallocz(align_offset(new_l1_size2, 512));
+ new_l1_table = g_malloc0(align_offset(new_l1_size2, 512));
memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
/* write new table (align to cluster) */
BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE);
new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2);
if (new_l1_table_offset < 0) {
- qemu_free(new_l1_table);
+ g_free(new_l1_table);
return new_l1_table_offset;
}
+ ret = qcow2_cache_flush(bs, s->refcount_block_cache);
+ 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]);
/* set new table */
BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE);
cpu_to_be32w((uint32_t*)data, new_l1_size);
- cpu_to_be64w((uint64_t*)(data + 4), new_l1_table_offset);
+ cpu_to_be64wu((uint64_t*)(data + 4), new_l1_table_offset);
ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size), data,sizeof(data));
if (ret < 0) {
goto fail;
}
- qemu_free(s->l1_table);
+ g_free(s->l1_table);
qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t));
s->l1_table_offset = new_l1_table_offset;
s->l1_table = new_l1_table;
s->l1_size = new_l1_size;
return 0;
fail:
- qemu_free(new_l1_table);
+ g_free(new_l1_table);
qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2);
return ret;
}
-void qcow2_l2_cache_reset(BlockDriverState *bs)
-{
- BDRVQcowState *s = bs->opaque;
-
- memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
- memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
- memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
-}
-
-static inline int l2_cache_new_entry(BlockDriverState *bs)
-{
- BDRVQcowState *s = bs->opaque;
- uint32_t min_count;
- int min_index, i;
-
- /* find a new entry in the least used one */
- min_index = 0;
- min_count = 0xffffffff;
- for(i = 0; i < L2_CACHE_SIZE; i++) {
- if (s->l2_cache_counts[i] < min_count) {
- min_count = s->l2_cache_counts[i];
- min_index = i;
- }
- }
- return min_index;
-}
-
-/*
- * seek_l2_table
- *
- * seek l2_offset in the l2_cache table
- * if not found, return NULL,
- * if found,
- * increments the l2 cache hit count of the entry,
- * if counter overflow, divide by two all counters
- * return the pointer to the l2 cache entry
- *
- */
-
-static uint64_t *seek_l2_table(BDRVQcowState *s, uint64_t l2_offset)
-{
- int i, j;
-
- for(i = 0; i < L2_CACHE_SIZE; i++) {
- if (l2_offset == s->l2_cache_offsets[i]) {
- /* increment the hit count */
- if (++s->l2_cache_counts[i] == 0xffffffff) {
- for(j = 0; j < L2_CACHE_SIZE; j++) {
- s->l2_cache_counts[j] >>= 1;
- }
- }
- return s->l2_cache + (i << s->l2_bits);
- }
- }
- return NULL;
-}
-
/*
* l2_load
*
uint64_t **l2_table)
{
BDRVQcowState *s = bs->opaque;
- int min_index;
int ret;
- /* seek if the table for the given offset is in the cache */
-
- *l2_table = seek_l2_table(s, l2_offset);
- if (*l2_table != NULL) {
- return 0;
- }
-
- /* not found: load a new entry in the least used one */
-
- min_index = l2_cache_new_entry(bs);
- *l2_table = s->l2_cache + (min_index << s->l2_bits);
-
- BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
- ret = bdrv_pread(bs->file, l2_offset, *l2_table,
- s->l2_size * sizeof(uint64_t));
- if (ret < 0) {
- return ret;
- }
+ ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, (void**) l2_table);
- s->l2_cache_offsets[min_index] = l2_offset;
- s->l2_cache_counts[min_index] = 1;
-
- return 0;
+ return ret;
}
/*
static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
{
BDRVQcowState *s = bs->opaque;
- int min_index;
uint64_t old_l2_offset;
uint64_t *l2_table;
int64_t l2_offset;
old_l2_offset = s->l1_table[l1_index];
+ trace_qcow2_l2_allocate(bs, l1_index);
+
/* allocate a new l2 entry */
l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
return l2_offset;
}
+ ret = qcow2_cache_flush(bs, s->refcount_block_cache);
+ if (ret < 0) {
+ goto fail;
+ }
+
/* allocate a new entry in the l2 cache */
- min_index = l2_cache_new_entry(bs);
- l2_table = s->l2_cache + (min_index << s->l2_bits);
+ trace_qcow2_l2_allocate_get_empty(bs, l1_index);
+ ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table);
+ if (ret < 0) {
+ return ret;
+ }
+
+ l2_table = *table;
if (old_l2_offset == 0) {
/* if there was no old l2 table, clear the new table */
memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
} else {
+ uint64_t* old_table;
+
/* if there was an old l2 table, read it from the disk */
BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
- ret = bdrv_pread(bs->file, old_l2_offset, l2_table,
- s->l2_size * sizeof(uint64_t));
+ ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_offset,
+ (void**) &old_table);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ memcpy(l2_table, old_table, s->cluster_size);
+
+ ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &old_table);
if (ret < 0) {
goto fail;
}
}
+
/* write the l2 table to the file */
BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);
- ret = bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
- s->l2_size * sizeof(uint64_t));
+
+ trace_qcow2_l2_allocate_write_l2(bs, l1_index);
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
+ ret = qcow2_cache_flush(bs, s->l2_table_cache);
if (ret < 0) {
goto fail;
}
/* 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);
if (ret < 0) {
goto fail;
}
- /* update the l2 cache entry */
-
- s->l2_cache_offsets[min_index] = l2_offset;
- s->l2_cache_counts[min_index] = 1;
-
*table = l2_table;
+ trace_qcow2_l2_allocate_done(bs, l1_index, 0);
return 0;
fail:
+ trace_qcow2_l2_allocate_done(bs, l1_index, ret);
+ qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
s->l1_table[l1_index] = old_l2_offset;
- qcow2_l2_cache_reset(bs);
return ret;
}
+/*
+ * Checks how many clusters in a given L2 table 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)
+ */
static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size,
- uint64_t *l2_table, uint64_t start, uint64_t mask)
+ uint64_t *l2_table, uint64_t start, uint64_t stop_flags)
{
int i;
- uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask;
+ uint64_t mask = stop_flags | L2E_OFFSET_MASK;
+ uint64_t offset = be64_to_cpu(l2_table[0]) & mask;
if (!offset)
return 0;
- for (i = start; i < start + nb_clusters; i++)
- if (offset + (uint64_t) i * cluster_size != (be64_to_cpu(l2_table[i]) & ~mask))
+ for (i = start; i < start + nb_clusters; i++) {
+ uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask;
+ if (offset + (uint64_t) i * cluster_size != l2_entry) {
break;
+ }
+ }
return (i - start);
}
static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table)
{
- int i = 0;
+ int i;
- while(nb_clusters-- && l2_table[i] == 0)
- i++;
+ for (i = 0; i < nb_clusters; i++) {
+ int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i]));
+
+ if (type != QCOW2_CLUSTER_UNALLOCATED) {
+ break;
+ }
+ }
return i;
}
}
}
-
-static int qcow_read(BlockDriverState *bs, int64_t sector_num,
- uint8_t *buf, int nb_sectors)
+static int coroutine_fn copy_sectors(BlockDriverState *bs,
+ uint64_t start_sect,
+ uint64_t cluster_offset,
+ int n_start, int n_end)
{
BDRVQcowState *s = bs->opaque;
- int ret, index_in_cluster, n, n1;
- uint64_t cluster_offset;
-
- while (nb_sectors > 0) {
- n = nb_sectors;
-
- ret = qcow2_get_cluster_offset(bs, sector_num << 9, &n,
- &cluster_offset);
- if (ret < 0) {
- return ret;
- }
+ QEMUIOVector qiov;
+ struct iovec iov;
+ int n, ret;
- index_in_cluster = sector_num & (s->cluster_sectors - 1);
- if (!cluster_offset) {
- if (bs->backing_hd) {
- /* read from the base image */
- n1 = qcow2_backing_read1(bs->backing_hd, sector_num, buf, n);
- if (n1 > 0) {
- BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING);
- ret = bdrv_read(bs->backing_hd, sector_num, buf, n1);
- if (ret < 0)
- return -1;
- }
- } else {
- memset(buf, 0, 512 * n);
- }
- } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
- if (qcow2_decompress_cluster(bs, cluster_offset) < 0)
- return -1;
- memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
- } else {
- BLKDBG_EVENT(bs->file, BLKDBG_READ);
- ret = bdrv_pread(bs->file, cluster_offset + index_in_cluster * 512, buf, n * 512);
- if (ret != n * 512)
- return -1;
- if (s->crypt_method) {
- qcow2_encrypt_sectors(s, sector_num, buf, buf, n, 0,
- &s->aes_decrypt_key);
- }
- }
- nb_sectors -= n;
- sector_num += n;
- buf += n * 512;
+ /*
+ * If this is the last cluster and it is only partially used, we must only
+ * copy until the end of the image, or bdrv_check_request will fail for the
+ * bdrv_read/write calls below.
+ */
+ if (start_sect + n_end > bs->total_sectors) {
+ n_end = bs->total_sectors - start_sect;
}
- return 0;
-}
-
-static int copy_sectors(BlockDriverState *bs, uint64_t start_sect,
- uint64_t cluster_offset, int n_start, int n_end)
-{
- BDRVQcowState *s = bs->opaque;
- int n, ret;
n = n_end - n_start;
- if (n <= 0)
+ if (n <= 0) {
return 0;
+ }
+
+ iov.iov_len = n * BDRV_SECTOR_SIZE;
+ iov.iov_base = qemu_blockalign(bs, iov.iov_len);
+
+ qemu_iovec_init_external(&qiov, &iov, 1);
+
BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
- ret = qcow_read(bs, start_sect + n_start, s->cluster_data, n);
- if (ret < 0)
- return ret;
+
+ /* 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.
+ */
+ ret = bs->drv->bdrv_co_readv(bs, start_sect + n_start, n, &qiov);
+ if (ret < 0) {
+ goto out;
+ }
+
if (s->crypt_method) {
qcow2_encrypt_sectors(s, start_sect + n_start,
- s->cluster_data,
- s->cluster_data, n, 1,
+ iov.iov_base, iov.iov_base, n, 1,
&s->aes_encrypt_key);
}
+
BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
- ret = bdrv_write_sync(bs->file, (cluster_offset >> 9) + n_start,
- s->cluster_data, n);
- if (ret < 0)
- return ret;
- return 0;
+ ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + n_start, n, &qiov);
+ if (ret < 0) {
+ goto out;
+ }
+
+ ret = 0;
+out:
+ qemu_vfree(iov.iov_base);
+ return ret;
}
* For a given offset of the disk image, find the cluster offset in
* qcow2 file. The offset is stored in *cluster_offset.
*
- * on entry, *num is the number of contiguous clusters we'd like to
+ * on entry, *num is the number of contiguous sectors we'd like to
* access following offset.
*
- * on exit, *num is the number of contiguous clusters we can read.
- *
- * Return 0, if the offset is found
- * Return -errno, otherwise.
+ * on exit, *num is the number of contiguous sectors we can read.
*
+ * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
+ * cases.
*/
-
int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
int *num, uint64_t *cluster_offset)
{
/* seek the the l2 offset in the l1 table */
l1_index = offset >> l1_bits;
- if (l1_index >= s->l1_size)
+ if (l1_index >= s->l1_size) {
+ ret = QCOW2_CLUSTER_UNALLOCATED;
goto out;
+ }
- l2_offset = s->l1_table[l1_index];
-
- /* seek the l2 table of the given l2 offset */
-
- if (!l2_offset)
+ l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
+ if (!l2_offset) {
+ ret = QCOW2_CLUSTER_UNALLOCATED;
goto out;
+ }
/* load the l2 table in memory */
- l2_offset &= ~QCOW_OFLAG_COPIED;
ret = l2_load(bs, l2_offset, &l2_table);
if (ret < 0) {
return ret;
*cluster_offset = be64_to_cpu(l2_table[l2_index]);
nb_clusters = size_to_clusters(s, nb_needed << 9);
- if (!*cluster_offset) {
+ ret = qcow2_get_cluster_type(*cluster_offset);
+ switch (ret) {
+ case QCOW2_CLUSTER_COMPRESSED:
+ /* Compressed clusters can only be processed one by one */
+ c = 1;
+ *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
+ break;
+ case QCOW2_CLUSTER_UNALLOCATED:
/* how many empty clusters ? */
c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]);
- } else {
+ *cluster_offset = 0;
+ break;
+ case QCOW2_CLUSTER_NORMAL:
/* how many allocated clusters ? */
c = count_contiguous_clusters(nb_clusters, s->cluster_size,
- &l2_table[l2_index], 0, QCOW_OFLAG_COPIED);
+ &l2_table[l2_index], 0, QCOW_OFLAG_COMPRESSED);
+ *cluster_offset &= L2E_OFFSET_MASK;
+ break;
}
- nb_available = (c * s->cluster_sectors);
+ qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+
+ nb_available = (c * s->cluster_sectors);
+
out:
if (nb_available > nb_needed)
nb_available = nb_needed;
*num = nb_available - index_in_cluster;
- *cluster_offset &=~QCOW_OFLAG_COPIED;
- return 0;
+ return ret;
}
/*
*/
static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
uint64_t **new_l2_table,
- uint64_t *new_l2_offset,
int *new_l2_index)
{
BDRVQcowState *s = bs->opaque;
l1_index = offset >> (s->l2_bits + s->cluster_bits);
if (l1_index >= s->l1_size) {
- ret = qcow2_grow_l1_table(bs, l1_index + 1);
+ ret = qcow2_grow_l1_table(bs, l1_index + 1, false);
if (ret < 0) {
return ret;
}
return ret;
}
} else {
- if (l2_offset)
- qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t));
+ /* First allocate a new L2 table (and do COW if needed) */
ret = l2_allocate(bs, l1_index, &l2_table);
if (ret < 0) {
return ret;
}
+
+ /* Then decrease the refcount of the old table */
+ if (l2_offset) {
+ qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t));
+ }
l2_offset = s->l1_table[l1_index] & ~QCOW_OFLAG_COPIED;
}
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
*new_l2_table = l2_table;
- *new_l2_offset = l2_offset;
*new_l2_index = l2_index;
return 0;
{
BDRVQcowState *s = bs->opaque;
int l2_index, ret;
- uint64_t l2_offset, *l2_table;
+ uint64_t *l2_table;
int64_t cluster_offset;
int nb_csectors;
- ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
+ ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
if (ret < 0) {
return 0;
}
cluster_offset = be64_to_cpu(l2_table[l2_index]);
- if (cluster_offset & QCOW_OFLAG_COPIED)
- return cluster_offset & ~QCOW_OFLAG_COPIED;
+ if (cluster_offset & QCOW_OFLAG_COPIED) {
+ qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+ return 0;
+ }
if (cluster_offset)
qcow2_free_any_clusters(bs, cluster_offset, 1);
cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
if (cluster_offset < 0) {
+ qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
return 0;
}
/* compressed clusters never have the copied flag */
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
l2_table[l2_index] = cpu_to_be64(cluster_offset);
- if (bdrv_pwrite_sync(bs->file,
- l2_offset + l2_index * sizeof(uint64_t),
- l2_table + l2_index,
- sizeof(uint64_t)) < 0)
- return 0;
-
- return cluster_offset;
-}
-
-/*
- * Write L2 table updates to disk, writing whole sectors to avoid a
- * read-modify-write in bdrv_pwrite
- */
-#define L2_ENTRIES_PER_SECTOR (512 / 8)
-static int write_l2_entries(BlockDriverState *bs, uint64_t *l2_table,
- uint64_t l2_offset, int l2_index, int num)
-{
- int l2_start_index = l2_index & ~(L1_ENTRIES_PER_SECTOR - 1);
- int start_offset = (8 * l2_index) & ~511;
- int end_offset = (8 * (l2_index + num) + 511) & ~511;
- size_t len = end_offset - start_offset;
- int ret;
-
- BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
- ret = bdrv_pwrite(bs->file, l2_offset + start_offset,
- &l2_table[l2_start_index], len);
+ ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
if (ret < 0) {
- return ret;
+ return 0;
}
- return 0;
+ return cluster_offset;
}
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, start_sect, l2_offset, *l2_table;
- uint64_t cluster_offset = m->cluster_offset;
+ 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);
if (m->nb_clusters == 0)
return 0;
- old_cluster = qemu_malloc(m->nb_clusters * sizeof(uint64_t));
+ old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
/* 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;
}
- /* update L2 table */
- ret = get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index);
+ /*
+ * 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_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;
}
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
for (i = 0; i < m->nb_clusters; i++) {
/* if two concurrent writes happen to the same unallocated cluster
(i << s->cluster_bits)) | QCOW_OFLAG_COPIED);
}
- ret = write_l2_entries(bs, l2_table, l2_offset, l2_index, m->nb_clusters);
+
+ ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
if (ret < 0) {
- qcow2_l2_cache_reset(bs);
goto err;
}
* Also flush bs->file to get the right order for L2 and refcount update.
*/
if (j != 0) {
- bdrv_flush(bs->file);
for (i = 0; i < j; i++) {
qcow2_free_any_clusters(bs,
be64_to_cpu(old_cluster[i]) & ~QCOW_OFLAG_COPIED, 1);
ret = 0;
err:
- qemu_free(old_cluster);
+ g_free(old_cluster);
return ret;
}
/*
- * alloc_cluster_offset
- *
- * For a given offset of the disk image, return 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,
- * m->depends_on is set to NULL and the 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. This may be 0 if the request
- * conflict with another write request in flight; in this case, m->depends_on
- * is set and the remaining fields of m are meaningless.
- *
- * If m->nb_clusters is non-zero, the other fields of m are valid and contain
- * information about the first allocated cluster.
- *
- * Return 0 on success and -errno in error cases
+ * 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)
*/
-int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
- int n_start, int n_end, int *num, QCowL2Meta *m)
+static int count_cow_clusters(BDRVQcowState *s, int nb_clusters,
+ uint64_t *l2_table, int l2_index)
{
- BDRVQcowState *s = bs->opaque;
- int l2_index, ret;
- uint64_t l2_offset, *l2_table;
- int64_t cluster_offset;
- unsigned int nb_clusters, i = 0;
- QCowL2Meta *old_alloc;
-
- ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
- if (ret < 0) {
- return ret;
- }
-
- nb_clusters = size_to_clusters(s, n_end << 9);
-
- nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
-
- cluster_offset = be64_to_cpu(l2_table[l2_index]);
-
- /* We keep all QCOW_OFLAG_COPIED clusters */
-
- if (cluster_offset & QCOW_OFLAG_COPIED) {
- nb_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size,
- &l2_table[l2_index], 0, 0);
-
- cluster_offset &= ~QCOW_OFLAG_COPIED;
- m->nb_clusters = 0;
- m->depends_on = NULL;
-
- goto out;
- }
-
- /* for the moment, multiple compressed clusters are not managed */
-
- if (cluster_offset & QCOW_OFLAG_COMPRESSED)
- nb_clusters = 1;
-
- /* how many available clusters ? */
+ int i = 0;
+ uint64_t cluster_offset;
while (i < nb_clusters) {
i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,
- &l2_table[l2_index], i, 0);
+ &l2_table[l2_index], i,
+ QCOW_OFLAG_COPIED | QCOW_OFLAG_COMPRESSED);
if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) {
break;
}
(cluster_offset & QCOW_OFLAG_COMPRESSED))
break;
}
+
assert(i <= nb_clusters);
- nb_clusters = i;
+ return i;
+}
+
+/*
+ * 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, uint64_t *l2_table)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t cluster_offset;
+ QCowL2Meta *old_alloc;
+
+ 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
*/
QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
- uint64_t end_offset = offset + nb_clusters * s->cluster_size;
- uint64_t old_offset = old_alloc->offset;
- uint64_t old_end_offset = old_alloc->offset +
- old_alloc->nb_clusters * s->cluster_size;
+ 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;
- if (end_offset < old_offset || offset > old_end_offset) {
+ if (end < old_start || start > old_end) {
/* No intersection */
} else {
- if (offset < old_offset) {
+ if (start < old_start) {
/* Stop at the start of a running allocation */
- nb_clusters = (old_offset - offset) >> s->cluster_bits;
+ *nb_clusters = old_start - start;
} else {
- nb_clusters = 0;
+ *nb_clusters = 0;
}
- if (nb_clusters == 0) {
- /* Set dependency and wait for a callback */
- m->depends_on = old_alloc;
- m->nb_clusters = 0;
- *num = 0;
- return 0;
+ if (*nb_clusters == 0) {
+ /* Wait for the dependency to complete. We need to recheck
+ * the free/allocated clusters when we continue. */
+ qemu_co_mutex_unlock(&s->lock);
+ qemu_co_queue_wait(&old_alloc->dependent_requests);
+ qemu_co_mutex_lock(&s->lock);
+ return -EAGAIN;
}
}
}
- if (!nb_clusters) {
+ if (!*nb_clusters) {
abort();
}
- QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight);
-
- /* allocate a new cluster */
+ /* 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);
+ }
- cluster_offset = qcow2_alloc_clusters(bs, nb_clusters * s->cluster_size);
if (cluster_offset < 0) {
- QLIST_REMOVE(m, next_in_flight);
return cluster_offset;
}
+ *host_offset = cluster_offset;
+ return 0;
+}
+
+/*
+ * 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, QCowL2Meta *m)
+{
+ BDRVQcowState *s = bs->opaque;
+ int l2_index, ret, sectors;
+ uint64_t *l2_table;
+ unsigned int nb_clusters, keep_clusters;
+ uint64_t cluster_offset;
- /* save info needed for meta data update */
- m->offset = offset;
- m->n_start = n_start;
- m->nb_clusters = nb_clusters;
+ trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset,
+ n_start, n_end);
-out:
- m->nb_available = MIN(nb_clusters << (s->cluster_bits - 9), n_end);
- m->cluster_offset = cluster_offset;
+ /* Find L2 entry for the first involved cluster */
+ ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
+ if (ret < 0) {
+ return ret;
+ }
- *num = m->nb_available - n_start;
+ /*
+ * Calculate the number of clusters to look for. We stop at L2 table
+ * boundaries to keep things simple.
+ */
+again:
+ nb_clusters = MIN(size_to_clusters(s, n_end << BDRV_SECTOR_BITS),
+ s->l2_size - l2_index);
+
+ 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.
+ */
+ if (cluster_offset & QCOW_OFLAG_COPIED) {
+ /* 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);
+ assert(keep_clusters <= nb_clusters);
+ nb_clusters -= keep_clusters;
+ } else {
+ /* For the moment, overwrite compressed clusters one by one */
+ if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
+ nb_clusters = 1;
+ } else {
+ nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, l2_index);
+ }
+
+ keep_clusters = 0;
+ cluster_offset = 0;
+ }
+
+ cluster_offset &= ~QCOW_OFLAG_COPIED;
+
+ /* If there is something left to allocate, do that now */
+ *m = (QCowL2Meta) {
+ .cluster_offset = cluster_offset,
+ .nb_clusters = 0,
+ };
+ qemu_co_queue_init(&m->dependent_requests);
+
+ if (nb_clusters > 0) {
+ uint64_t alloc_offset;
+ uint64_t alloc_cluster_offset;
+ uint64_t keep_bytes = keep_clusters * s->cluster_size;
+
+ /* Calculate start and size of allocation */
+ alloc_offset = offset + keep_bytes;
+
+ if (keep_clusters == 0) {
+ alloc_cluster_offset = 0;
+ } else {
+ alloc_cluster_offset = cluster_offset + keep_bytes;
+ }
+
+ /* Allocate, if necessary at a given offset in the image file */
+ ret = do_alloc_cluster_offset(bs, alloc_offset, &alloc_cluster_offset,
+ &nb_clusters, l2_table);
+ if (ret == -EAGAIN) {
+ goto again;
+ } else if (ret < 0) {
+ goto fail;
+ }
+
+ /* 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);
+ }
+ }
+
+ /* Some cleanup work */
+ ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+ if (ret < 0) {
+ goto fail_put;
+ }
+
+ sectors = (keep_clusters + nb_clusters) << (s->cluster_bits - 9);
+ if (sectors > n_end) {
+ sectors = n_end;
+ }
+
+ assert(sectors > n_start);
+ *num = sectors - n_start;
return 0;
+
+fail:
+ qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+fail_put:
+ 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,
BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
ret = bdrv_read(bs->file, coffset >> 9, s->cluster_data, nb_csectors);
if (ret < 0) {
- return -1;
+ return ret;
}
if (decompress_buffer(s->cluster_cache, s->cluster_size,
s->cluster_data + sector_offset, csize) < 0) {
- return -1;
+ return -EIO;
}
s->cluster_cache_offset = coffset;
}
return 0;
}
+
+/*
+ * This discards as many clusters of nb_clusters as possible at once (i.e.
+ * all clusters in the same L2 table) and returns the number of discarded
+ * clusters.
+ */
+static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
+ unsigned int nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t *l2_table;
+ int l2_index;
+ int ret;
+ int i;
+
+ ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* Limit nb_clusters to one L2 table */
+ nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+
+ for (i = 0; i < nb_clusters; i++) {
+ uint64_t old_offset;
+
+ old_offset = be64_to_cpu(l2_table[l2_index + i]);
+ old_offset &= ~QCOW_OFLAG_COPIED;
+
+ if (old_offset == 0) {
+ continue;
+ }
+
+ /* First remove L2 entries */
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
+ l2_table[l2_index + i] = cpu_to_be64(0);
+
+ /* Then decrease the refcount */
+ qcow2_free_any_clusters(bs, old_offset, 1);
+ }
+
+ ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return nb_clusters;
+}
+
+int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
+ int nb_sectors)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t end_offset;
+ unsigned int nb_clusters;
+ int ret;
+
+ end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS);
+
+ /* Round start up and end down */
+ offset = align_offset(offset, s->cluster_size);
+ end_offset &= ~(s->cluster_size - 1);
+
+ if (offset > end_offset) {
+ return 0;
+ }
+
+ nb_clusters = size_to_clusters(s, end_offset - offset);
+
+ /* Each L2 table is handled by its own loop iteration */
+ while (nb_clusters > 0) {
+ ret = discard_single_l2(bs, offset, nb_clusters);
+ if (ret < 0) {
+ return ret;
+ }
+
+ nb_clusters -= ret;
+ offset += (ret * s->cluster_size);
+ }
+
+ return 0;
+}
projects / qemu.git / blobdiff