diff options
| author | Stefan Hajnoczi <stefanha@redhat.com> | 2013-04-15 17:17:32 +0200 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2013-04-22 10:27:58 +0200 |
| commit | 16b3c5cd9f27678bc9d6707664640653b47533b9 (patch) | |
| tree | f651cee5296cf7f98e270b87854dda286b40c43d /block | |
| parent | f4d38bef7cc79018e2aa789b0e4c23c3a8cdfca5 (diff) | |
qcow: allow sub-cluster compressed write to last cluster
Compression in qcow requires image length to be a multiple of the
cluster size. Lift this requirement by zero-padding the final cluster
when necessary. The virtual disk size is still not cluster-aligned, so
the guest cannot access the zero sectors.
Note that this is almost identical to the qcow2 version of this code.
qcow2's compression code is drawn from qcow.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/qcow.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/block/qcow.c b/block/qcow.c index 3278e552bf..e2a64c79b1 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -787,8 +787,21 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num, uint8_t *out_buf; uint64_t cluster_offset; - if (nb_sectors != s->cluster_sectors) - return -EINVAL; + if (nb_sectors != s->cluster_sectors) { + ret = -EINVAL; + + /* Zero-pad last write if image size is not cluster aligned */ + if (sector_num + nb_sectors == bs->total_sectors && + nb_sectors < s->cluster_sectors) { + uint8_t *pad_buf = qemu_blockalign(bs, s->cluster_size); + memset(pad_buf, 0, s->cluster_size); + memcpy(pad_buf, buf, nb_sectors * BDRV_SECTOR_SIZE); + ret = qcow_write_compressed(bs, sector_num, + pad_buf, s->cluster_sectors); + qemu_vfree(pad_buf); + } + return ret; + } out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); |