Oops I forgot max_transfer needs to be in bytes (and BLKSECTGET in sg has always been implemented wrongly). Will send a new version.
On Fri, 4 Sep 2020 at 06:37, Tom Yan <tom.t...@gmail.com> wrote: > > sg_get_max_transfer_length() and sg_get_max_segments() have nothing > to do with the sg driver or SG_IO at all. They can be and should be > used on all host devices / cdroms (on Linux). > > Also use MIN_NON_ZERO instead when we clamp max_sectors against > max_segments. > > Signed-off-by: Tom Yan <tom.t...@gmail.com> > --- > block/file-posix.c | 39 ++++++++++++++++++++++----------------- > 1 file changed, 22 insertions(+), 17 deletions(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index 9a00d4190a..a38f43af4f 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -1163,7 +1163,7 @@ static void raw_reopen_abort(BDRVReopenState *state) > s->reopen_state = NULL; > } > > -static int sg_get_max_transfer_length(int fd) > +static int get_max_transfer_length(int fd) > { > #ifdef BLKSECTGET > int max_bytes = 0; > @@ -1178,7 +1178,7 @@ static int sg_get_max_transfer_length(int fd) > #endif > } > > -static int sg_get_max_segments(int fd) > +static int get_max_segments(int fd) > { > #ifdef CONFIG_LINUX > char buf[32]; > @@ -1233,23 +1233,28 @@ static void raw_refresh_limits(BlockDriverState *bs, > Error **errp) > { > BDRVRawState *s = bs->opaque; > > - if (bs->sg) { > - int ret = sg_get_max_transfer_length(s->fd); > + raw_probe_alignment(bs, s->fd, errp); > + bs->bl.min_mem_alignment = s->buf_align; > + bs->bl.opt_mem_alignment = MAX(s->buf_align, qemu_real_host_page_size); > +} > > - if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) { > - bs->bl.max_transfer = pow2floor(ret); > - } > +static void hdev_refresh_limits(BlockDriverState *bs, Error **errp) > +{ > + BDRVRawState *s = bs->opaque; > > - ret = sg_get_max_segments(s->fd); > - if (ret > 0) { > - bs->bl.max_transfer = MIN(bs->bl.max_transfer, > - ret * qemu_real_host_page_size); > - } > + int ret = get_max_transfer_length(s->fd); > + > + if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) { > + bs->bl.max_transfer = pow2floor(ret); > } > > - raw_probe_alignment(bs, s->fd, errp); > - bs->bl.min_mem_alignment = s->buf_align; > - bs->bl.opt_mem_alignment = MAX(s->buf_align, qemu_real_host_page_size); > + ret = get_max_segments(s->fd); > + if (ret > 0) { > + bs->bl.max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, > + ret * qemu_real_host_page_size); > + } > + > + raw_refresh_limits(bs, errp); > } > > static int check_for_dasd(int fd) > @@ -3604,7 +3609,7 @@ static BlockDriver bdrv_host_device = { > .bdrv_co_pdiscard = hdev_co_pdiscard, > .bdrv_co_copy_range_from = raw_co_copy_range_from, > .bdrv_co_copy_range_to = raw_co_copy_range_to, > - .bdrv_refresh_limits = raw_refresh_limits, > + .bdrv_refresh_limits = hdev_refresh_limits, > .bdrv_io_plug = raw_aio_plug, > .bdrv_io_unplug = raw_aio_unplug, > .bdrv_attach_aio_context = raw_aio_attach_aio_context, > @@ -3728,7 +3733,7 @@ static BlockDriver bdrv_host_cdrom = { > .bdrv_co_preadv = raw_co_preadv, > .bdrv_co_pwritev = raw_co_pwritev, > .bdrv_co_flush_to_disk = raw_co_flush_to_disk, > - .bdrv_refresh_limits = raw_refresh_limits, > + .bdrv_refresh_limits = hdev_refresh_limits, > .bdrv_io_plug = raw_aio_plug, > .bdrv_io_unplug = raw_aio_unplug, > .bdrv_attach_aio_context = raw_aio_attach_aio_context, > -- > 2.28.0 >