diff options
| -rw-r--r-- | block/null.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/block/null.c b/block/null.c index 00bc6e478a..7646bb0e23 100644 --- a/block/null.c +++ b/block/null.c @@ -15,10 +15,12 @@ #include "block/block_int.h" #define NULL_OPT_LATENCY "latency-ns" +#define NULL_OPT_ZEROES "read-zeroes" typedef struct { int64_t length; int64_t latency_ns; + bool read_zeroes; } BDRVNullState; static QemuOptsList runtime_opts = { @@ -41,6 +43,11 @@ static QemuOptsList runtime_opts = { .help = "nanoseconds (approximated) to wait " "before completing request", }, + { + .name = NULL_OPT_ZEROES, + .type = QEMU_OPT_BOOL, + .help = "return zeroes when read", + }, { /* end of list */ } }, }; @@ -62,6 +69,7 @@ static int null_file_open(BlockDriverState *bs, QDict *options, int flags, error_setg(errp, "latency-ns is invalid"); ret = -EINVAL; } + s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false); qemu_opts_del(opts); return ret; } @@ -91,6 +99,12 @@ static coroutine_fn int null_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { + BDRVNullState *s = bs->opaque; + + if (s->read_zeroes) { + qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE); + } + return null_co_common(bs); } @@ -160,6 +174,12 @@ static BlockAIOCB *null_aio_readv(BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque) { + BDRVNullState *s = bs->opaque; + + if (s->read_zeroes) { + qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE); + } + return null_aio_common(bs, cb, opaque); } |