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qcow2: aio support for compressed cluster read 

Allocate buffers locally and release qcow2 lock. Than, reads inside
qcow2_co_preadv_compressed may be done in parallel, however all
decompression is still done synchronously. Let's improve it in the
following commit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2018-11-01 21:27:37 +03:00 committed by Kevin Wolf
parent c068a1cd52
commit c3c10f7295
2 changed files with 51 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

100
block/qcow2.c
View File

@ -74,6 +74,13 @@ typedef struct {
#define QCOW2_EXT_MAGIC_CRYPTO_HEADER 0x0537be77
#define QCOW2_EXT_MAGIC_BITMAPS 0x23852875
static int coroutine_fn
qcow2_co_preadv_compressed(BlockDriverState *bs,
uint64_t file_cluster_offset,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov);
static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
{
const QCowHeader *cow_header = (const void *)buf;
@ -1414,7 +1421,6 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
goto fail;
}
s->cluster_cache_offset = -1;
s->flags = flags;
ret = qcow2_refcount_init(bs);
@ -1914,15 +1920,15 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
break;
case QCOW2_CLUSTER_COMPRESSED:
/* add AIO support for compressed blocks ? */
ret = qcow2_decompress_cluster(bs, cluster_offset);
qemu_co_mutex_unlock(&s->lock);
ret = qcow2_co_preadv_compressed(bs, cluster_offset,
offset, cur_bytes,
&hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
qemu_iovec_from_buf(&hd_qiov, 0,
s->cluster_cache + offset_in_cluster,
cur_bytes);
break;
case QCOW2_CLUSTER_NORMAL:
@ -2058,8 +2064,6 @@ static coroutine_fn int qcow2_co_pwritev(BlockDriverState *bs, uint64_t offset,
qemu_iovec_init(&hd_qiov, qiov->niov);
s->cluster_cache_offset = -1; /* disable compressed cache */
qemu_co_mutex_lock(&s->lock);
while (bytes != 0) {
@ -2223,8 +2227,6 @@ static void qcow2_close(BlockDriverState *bs)
g_free(s->image_backing_file);
g_free(s->image_backing_format);
g_free(s->cluster_cache);
qemu_vfree(s->cluster_data);
qcow2_refcount_close(bs);
qcow2_free_snapshots(bs);
}
@ -3401,7 +3403,6 @@ qcow2_co_copy_range_to(BlockDriverState *bs,
QCowL2Meta *l2meta = NULL;
assert(!bs->encrypted);
s->cluster_cache_offset = -1; /* disable compressed cache */
qemu_co_mutex_lock(&s->lock);
@ -3957,52 +3958,53 @@ fail:
return ret;
}
int coroutine_fn
qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
static int coroutine_fn
qcow2_co_preadv_compressed(BlockDriverState *bs,
uint64_t file_cluster_offset,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov)
{
BDRVQcow2State *s = bs->opaque;
int ret, csize, nb_csectors;
int ret = 0, csize, nb_csectors;
uint64_t coffset;
uint8_t *buf, *out_buf;
struct iovec iov;
QEMUIOVector local_qiov;
int offset_in_cluster = offset_into_cluster(s, offset);
coffset = cluster_offset & s->cluster_offset_mask;
if (s->cluster_cache_offset != coffset) {
nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1;
csize = nb_csectors * 512 - (coffset & 511);
coffset = file_cluster_offset & s->cluster_offset_mask;
nb_csectors = ((file_cluster_offset >> s->csize_shift) & s->csize_mask) + 1;
csize = nb_csectors * 512 - (coffset & 511);
/* Allocate buffers on first decompress operation, most images are
* uncompressed and the memory overhead can be avoided. The buffers
* are freed in .bdrv_close().
*/
if (!s->cluster_data) {
/* one more sector for decompressed data alignment */
s->cluster_data = qemu_try_blockalign(bs->file->bs,
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size + 512);
if (!s->cluster_data) {
return -ENOMEM;
}
}
if (!s->cluster_cache) {
s->cluster_cache = g_malloc(s->cluster_size);
}
iov.iov_base = s->cluster_data;
iov.iov_len = csize;
qemu_iovec_init_external(&local_qiov, &iov, 1);
BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
ret = bdrv_co_preadv(bs->file, coffset, csize, &local_qiov, 0);
if (ret < 0) {
return ret;
}
if (qcow2_decompress(s->cluster_cache, s->cluster_size,
s->cluster_data, csize) < 0) {
return -EIO;
}
s->cluster_cache_offset = coffset;
buf = g_try_malloc(csize);
if (!buf) {
return -ENOMEM;
}
return 0;
iov.iov_base = buf;
iov.iov_len = csize;
qemu_iovec_init_external(&local_qiov, &iov, 1);
out_buf = qemu_blockalign(bs, s->cluster_size);
BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
ret = bdrv_co_preadv(bs->file, coffset, csize, &local_qiov, 0);
if (ret < 0) {
goto fail;
}
if (qcow2_decompress(out_buf, s->cluster_size, buf, csize) < 0) {
ret = -EIO;
goto fail;
}
qemu_iovec_from_buf(qiov, 0, out_buf + offset_in_cluster, bytes);
fail:
qemu_vfree(out_buf);
g_free(buf);
return ret;
}
static int make_completely_empty(BlockDriverState *bs)

4
block/qcow2.h
View File

@ -278,9 +278,6 @@ typedef struct BDRVQcow2State {
QEMUTimer *cache_clean_timer;
unsigned cache_clean_interval;
uint8_t *cluster_cache;
uint8_t *cluster_data;
uint64_t cluster_cache_offset;
QLIST_HEAD(QCowClusterAlloc, QCowL2Meta) cluster_allocs;
uint64_t *refcount_table;
@ -616,7 +613,6 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
bool exact_size);
int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t max_size);
int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
int qcow2_encrypt_sectors(BDRVQcow2State *s, int64_t sector_num,
uint8_t *buf, int nb_sectors, bool enc, Error **errp);