From fcccefc57f235c0928e60bba0b7f6084677ed3df Mon Sep 17 00:00:00 2001 From: Pavel Butsykin Date: Fri, 22 Jul 2016 11:17:43 +0300 Subject: [PATCH] qcow2: add qcow2_co_pwritev_compressed Added implementation of the qcow2_co_pwritev_compressed function that will allow us to safely use compressed writes for the qcow2 from running VMs. Signed-off-by: Pavel Butsykin Reviewed-by: Stefan Hajnoczi Signed-off-by: Denis V. Lunev CC: Jeff Cody CC: Markus Armbruster CC: Eric Blake CC: John Snow CC: Stefan Hajnoczi CC: Kevin Wolf Signed-off-by: Kevin Wolf --- block/qcow2.c | 124 ++++++++++++++++++++------------------------------ 1 file changed, 50 insertions(+), 74 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 91ef4dfefc..1cbaa8f030 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2533,84 +2533,49 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset) return 0; } -typedef struct Qcow2WriteCo { - BlockDriverState *bs; - int64_t sector_num; - const uint8_t *buf; - int nb_sectors; - int ret; -} Qcow2WriteCo; - -static void qcow2_write_co_entry(void *opaque) -{ - Qcow2WriteCo *co = opaque; - QEMUIOVector qiov; - uint64_t offset = co->sector_num * BDRV_SECTOR_SIZE; - uint64_t bytes = co->nb_sectors * BDRV_SECTOR_SIZE; - - struct iovec iov = (struct iovec) { - .iov_base = (uint8_t*) co->buf, - .iov_len = bytes, - }; - qemu_iovec_init_external(&qiov, &iov, 1); - - co->ret = qcow2_co_pwritev(co->bs, offset, bytes, &qiov, 0); -} - -/* Wrapper for non-coroutine contexts */ -static int qcow2_write(BlockDriverState *bs, int64_t sector_num, - const uint8_t *buf, int nb_sectors) -{ - Coroutine *co; - AioContext *aio_context = bdrv_get_aio_context(bs); - Qcow2WriteCo data = { - .bs = bs, - .sector_num = sector_num, - .buf = buf, - .nb_sectors = nb_sectors, - .ret = -EINPROGRESS, - }; - co = qemu_coroutine_create(qcow2_write_co_entry, &data); - qemu_coroutine_enter(co); - while (data.ret == -EINPROGRESS) { - aio_poll(aio_context, true); - } - return data.ret; -} - /* XXX: put compressed sectors first, then all the cluster aligned tables to avoid losing bytes in alignment */ -static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, - const uint8_t *buf, int nb_sectors) +static coroutine_fn int +qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, + uint64_t bytes, QEMUIOVector *qiov) { BDRVQcow2State *s = bs->opaque; + QEMUIOVector hd_qiov; + struct iovec iov; z_stream strm; int ret, out_len; - uint8_t *out_buf; + uint8_t *buf, *out_buf; uint64_t cluster_offset; - if (nb_sectors == 0) { + if (bytes == 0) { /* align end of file to a sector boundary to ease reading with sector based I/Os */ cluster_offset = bdrv_getlength(bs->file->bs); return bdrv_truncate(bs->file->bs, cluster_offset); } - if (nb_sectors != s->cluster_sectors) { + if (bytes != s->cluster_size) { 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) { + if (offset + bytes == bs->total_sectors << BDRV_SECTOR_BITS && + bytes < s->cluster_size) + { 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 = qcow2_write_compressed(bs, sector_num, - pad_buf, s->cluster_sectors); + qemu_iovec_to_buf(qiov, 0, pad_buf, s->cluster_size); + iov = (struct iovec) { + .iov_base = pad_buf, + .iov_len = s->cluster_size, + }; + qemu_iovec_init_external(&hd_qiov, &iov, 1); + ret = qcow2_co_pwritev_compressed(bs, offset, bytes, &hd_qiov); qemu_vfree(pad_buf); } return ret; } + buf = qemu_blockalign(bs, s->cluster_size); + qemu_iovec_to_buf(qiov, 0, buf, s->cluster_size); out_buf = g_malloc(s->cluster_size); @@ -2641,33 +2606,44 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, if (ret != Z_STREAM_END || out_len >= s->cluster_size) { /* could not compress: write normal cluster */ - ret = qcow2_write(bs, sector_num, buf, s->cluster_sectors); + ret = qcow2_co_pwritev(bs, offset, bytes, qiov, 0); if (ret < 0) { goto fail; } - } else { - cluster_offset = qcow2_alloc_compressed_cluster_offset(bs, - sector_num << 9, out_len); - if (!cluster_offset) { - ret = -EIO; - goto fail; - } - cluster_offset &= s->cluster_offset_mask; + goto success; + } - ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len); - if (ret < 0) { - goto fail; - } + qemu_co_mutex_lock(&s->lock); + cluster_offset = + qcow2_alloc_compressed_cluster_offset(bs, offset, out_len); + if (!cluster_offset) { + qemu_co_mutex_unlock(&s->lock); + ret = -EIO; + goto fail; + } + cluster_offset &= s->cluster_offset_mask; - BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED); - ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len); - if (ret < 0) { - goto fail; - } + ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len); + qemu_co_mutex_unlock(&s->lock); + if (ret < 0) { + goto fail; } + iov = (struct iovec) { + .iov_base = out_buf, + .iov_len = out_len, + }; + qemu_iovec_init_external(&hd_qiov, &iov, 1); + + BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED); + ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0); + if (ret < 0) { + goto fail; + } +success: ret = 0; fail: + qemu_vfree(buf); g_free(out_buf); return ret; } @@ -3412,7 +3388,7 @@ BlockDriver bdrv_qcow2 = { .bdrv_co_pwrite_zeroes = qcow2_co_pwrite_zeroes, .bdrv_co_pdiscard = qcow2_co_pdiscard, .bdrv_truncate = qcow2_truncate, - .bdrv_write_compressed = qcow2_write_compressed, + .bdrv_co_pwritev_compressed = qcow2_co_pwritev_compressed, .bdrv_make_empty = qcow2_make_empty, .bdrv_snapshot_create = qcow2_snapshot_create, -- 2.39.2