block/parallels: read up to cluster end in one go
Teach parallels_read() to do reads in coarser granularity than just a
single sector: if requested, read up to the cluster end in one go.
Signed-off-by: Roman Kagan <rkagan@parallels.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1430207220-24458-5-git-send-email-den@openvz.org
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/block/parallels.c b/block/parallels.c
index baefd3e..8770c82 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -159,6 +159,13 @@
return (uint64_t)s->catalog_bitmap[index] * s->off_multiplier + offset;
}
+static int cluster_remainder(BDRVParallelsState *s, int64_t sector_num,
+ int nb_sectors)
+{
+ int ret = s->tracks - sector_num % s->tracks;
+ return MIN(nb_sectors, ret);
+}
+
static int parallels_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
@@ -166,17 +173,18 @@
while (nb_sectors > 0) {
int64_t position = seek_to_sector(s, sector_num);
+ int n = cluster_remainder(s, sector_num, nb_sectors);
if (position >= 0) {
- int ret = bdrv_read(bs->file, position, buf, 1);
+ int ret = bdrv_read(bs->file, position, buf, n);
if (ret < 0) {
return ret;
}
} else {
- memset(buf, 0, BDRV_SECTOR_SIZE);
+ memset(buf, 0, n << BDRV_SECTOR_BITS);
}
- nb_sectors--;
- sector_num++;
- buf += BDRV_SECTOR_SIZE;
+ nb_sectors -= n;
+ sector_num += n;
+ buf += n << BDRV_SECTOR_BITS;
}
return 0;
}
