| Message ID | 1458858840-3859-3-git-send-email-mreitz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 03/24/2016 04:33 PM, Max Reitz wrote: > This is optional so that it does not impede the null block driver's > performance unless this behavior is desired. > > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > block/null.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) Reviewed-by: Eric Blake <eblake@redhat.com>
On Thu, 03/24 23:33, Max Reitz wrote: > This is optional so that it does not impede the null block driver's > performance unless this behavior is desired. > > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > block/null.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/block/null.c b/block/null.c > index d90165d..a7df386 100644 > --- a/block/null.c > +++ b/block/null.c > @@ -14,10 +14,12 @@ > #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 = { > @@ -40,6 +42,11 @@ 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 */ } > }, > }; > @@ -61,6 +68,7 @@ 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; > } > @@ -90,6 +98,12 @@ 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); > } > > @@ -159,6 +173,12 @@ 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); > } > > -- > 2.7.4 > Acked-by: Fam Zheng <famz@redhat.com>
diff --git a/block/null.c b/block/null.c index d90165d..a7df386 100644 --- a/block/null.c +++ b/block/null.c @@ -14,10 +14,12 @@ #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 = { @@ -40,6 +42,11 @@ 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 */ } }, }; @@ -61,6 +68,7 @@ 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; } @@ -90,6 +98,12 @@ 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); } @@ -159,6 +173,12 @@ 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); }
This is optional so that it does not impede the null block driver's performance unless this behavior is desired. Signed-off-by: Max Reitz <mreitz@redhat.com> --- block/null.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)