2011/9/19 Kevin Wolf <kw...@redhat.com>: > Unlocking during COW allows for more parallelism. One change it requires is > that buffers are dynamically allocated instead of just using a per-image > buffer. > > While touching the code, drop the synchronous qcow2_read() function and > replace > it by a bdrv_read() call. > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > block/qcow2-cluster.c | 95 +++++++++++++----------------------------------- > 1 files changed, 26 insertions(+), 69 deletions(-) > > diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c > index c79323a..61b8e62 100644 > --- a/block/qcow2-cluster.c > +++ b/block/qcow2-cluster.c > @@ -289,89 +289,42 @@ void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t > sector_num, > } > } > > - > -static int qcow2_read(BlockDriverState *bs, int64_t sector_num, > - uint8_t *buf, int nb_sectors) > -{ > - BDRVQcowState *s = bs->opaque; > - int ret, index_in_cluster, n, n1; > - uint64_t cluster_offset; > - struct iovec iov; > - QEMUIOVector qiov; > - > - while (nb_sectors > 0) { > - n = nb_sectors; > - > - ret = qcow2_get_cluster_offset(bs, sector_num << 9, &n, > - &cluster_offset); > - if (ret < 0) { > - return ret; > - } > - > - index_in_cluster = sector_num & (s->cluster_sectors - 1); > - if (!cluster_offset) { > - if (bs->backing_hd) { > - /* read from the base image */ > - iov.iov_base = buf; > - iov.iov_len = n * 512; > - qemu_iovec_init_external(&qiov, &iov, 1); > - > - n1 = qcow2_backing_read1(bs->backing_hd, &qiov, sector_num, > 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; > - } > - 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; > + void *buf; > > n = n_end - n_start; > - if (n <= 0) > + if (n <= 0) { > return 0; > + } > + > + buf = qemu_blockalign(bs, n * BDRV_SECTOR_SIZE); > + > BLKDBG_EVENT(bs->file, BLKDBG_COW_READ); > - ret = qcow2_read(bs, start_sect + n_start, s->cluster_data, n); > - if (ret < 0) > - return ret; > + ret = bdrv_read(bs, start_sect + n_start, buf, n); > + 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, > + buf, buf, n, 1, > &s->aes_encrypt_key); > } > + > BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); > - ret = bdrv_write(bs->file, (cluster_offset >> 9) + n_start, > - s->cluster_data, n); > - if (ret < 0) > - return ret; > - return 0; > + ret = bdrv_write(bs->file, (cluster_offset >> 9) + n_start, buf, n); > + if (ret < 0) { > + goto out; > + } > + > + ret = 0; > +out: > + qemu_vfree(buf); > + return ret; > } > > > @@ -620,7 +573,9 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, > QCowL2Meta *m) > 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; > } > @@ -628,8 +583,10 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, > QCowL2Meta *m) > 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; > } > -- > 1.7.6.2 > >
Seems good, I like the idea to reuse bdrv_read instead of a new function. However I don't understand why (seems related to range checking in block.c) 028 iotest fails Frediano