This adds a preallocation=full mode to qcow2 image creation, which creates a non-sparse image file.
Signed-off-by: Hu Tao <hu...@cn.fujitsu.com> --- block/qcow2.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 359030f..d3ca6cf 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1385,7 +1385,13 @@ static int qcow2_change_backing_file(BlockDriverState *bs, return qcow2_update_header(bs); } -static int preallocate(BlockDriverState *bs) +enum prealloc_mode { + PREALLOC_OFF = 0, + PREALLOC_METADATA, + PREALLOC_FULL, +}; + +static int preallocate(BlockDriverState *bs, enum prealloc_mode mode) { uint64_t nb_sectors; uint64_t offset; @@ -1394,9 +1400,12 @@ static int preallocate(BlockDriverState *bs) int ret; QCowL2Meta *meta; + assert(mode != PREALLOC_OFF); + nb_sectors = bdrv_getlength(bs) >> 9; offset = 0; + /* First allocate metadata in _really_ big chunks */ while (nb_sectors) { num = MIN(nb_sectors, INT_MAX >> 9); ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, @@ -1424,6 +1433,11 @@ static int preallocate(BlockDriverState *bs) offset += num << 9; } + /* Then write zeros to the cluster data, if requested */ + if (mode == PREALLOC_FULL) { + bdrv_zero_init(bs->file, offset, bdrv_getlength(bs)); + } + /* * It is expected that the image file is large enough to actually contain * all of the allocated clusters (otherwise we get failing reads after @@ -1572,11 +1586,11 @@ static int qcow2_create2(const char *filename, int64_t total_size, } } - /* And if we're supposed to preallocate metadata, do that now */ + /* And if we're supposed to preallocate data, do that now */ if (prealloc) { BDRVQcowState *s = bs->opaque; qemu_co_mutex_lock(&s->lock); - ret = preallocate(bs); + ret = preallocate(bs, prealloc); qemu_co_mutex_unlock(&s->lock); if (ret < 0) { error_setg_errno(errp, -ret, "Could not preallocate metadata"); @@ -1629,9 +1643,11 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options, } } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) { if (!options->value.s || !strcmp(options->value.s, "off")) { - prealloc = 0; + prealloc = PREALLOC_OFF; } else if (!strcmp(options->value.s, "metadata")) { - prealloc = 1; + prealloc = PREALLOC_METADATA; + } else if (!strcmp(options->value.s, "full")) { + prealloc = PREALLOC_FULL; } else { error_setg(errp, "Invalid preallocation mode: '%s'", options->value.s); @@ -2221,7 +2237,7 @@ static QEMUOptionParameter qcow2_create_options[] = { { .name = BLOCK_OPT_PREALLOC, .type = OPT_STRING, - .help = "Preallocation mode (allowed values: off, metadata)" + .help = "Preallocation mode (allowed values: off, metadata, full)" }, { .name = BLOCK_OPT_LAZY_REFCOUNTS, -- 1.8.3.1