From 9de9da17d8304576e8402697bcee72c88ce499b8 Mon Sep 17 00:00:00 2001 From: Roman Kagan Date: Tue, 28 Apr 2015 10:46:37 +0300 Subject: 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 Reviewed-by: Denis V. Lunev Signed-off-by: Denis V. Lunev Reviewed-by: Stefan Hajnoczi Message-id: 1430207220-24458-5-git-send-email-den@openvz.org CC: Kevin Wolf Signed-off-by: Stefan Hajnoczi --- block/parallels.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'block/parallels.c') 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 @@ static int64_t seek_to_sector(BDRVParallelsState *s, int64_t sector_num) 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 @@ static int parallels_read(BlockDriverState *bs, int64_t sector_num, 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; } -- cgit v1.1