| Message ID | 20240725164536.1275851-1-w@uter.be (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | nbd: add support for rotational devices | expand |
On Thu, Jul 25, 2024 at 06:45:36PM GMT, Wouter Verhelst wrote: > The NBD protocol defines the flag NBD_FLAG_ROTATIONAL to flag that the > export in use should be treated as a rotational device. > > Add support for that flag to the kernel driver. > > Signed-off-by: Wouter Verhelst <w@uter.be> > --- > drivers/block/nbd.c | 3 +++ > include/uapi/linux/nbd.h | 3 ++- > 2 files changed, 5 insertions(+), 1 deletion(-) Reviewed-by: Eric Blake <eblake@redhat.com> For what it's worth, the nbdkit project recently made it possible to aad a filter on top of any existing NBD server to change the setting of the rotational bit[1], as well as a filter to intentionally simulate delays of a rotational device[2], in order to experiment with how much impact changing the bit can have when it is not ignored. [1] https://libguestfs.org/nbdkit-rotational-filter.1.html [2] https://libguestfs.org/nbdkit-spinning-filter.1.html
On Thu, 25 Jul 2024 18:45:36 +0200, Wouter Verhelst wrote: > The NBD protocol defines the flag NBD_FLAG_ROTATIONAL to flag that the > export in use should be treated as a rotational device. > > Add support for that flag to the kernel driver. > > Applied, thanks! [1/1] nbd: add support for rotational devices commit: 45c7d3321b0ce575705bb62b6069efad48a51d67 Best regards,
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 41a90150b501..5b1811b1ba5f 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -350,6 +350,9 @@ static int __nbd_set_size(struct nbd_device *nbd, loff_t bytesize, lim.features |= BLK_FEAT_WRITE_CACHE; lim.features &= ~BLK_FEAT_FUA; } + if (nbd->config->flags & NBD_FLAG_ROTATIONAL) + lim.features |= BLK_FEAT_ROTATIONAL; + lim.logical_block_size = blksize; lim.physical_block_size = blksize; error = queue_limits_commit_update(nbd->disk->queue, &lim); diff --git a/include/uapi/linux/nbd.h b/include/uapi/linux/nbd.h index 80ce0ef43afd..d75215f2c675 100644 --- a/include/uapi/linux/nbd.h +++ b/include/uapi/linux/nbd.h @@ -51,8 +51,9 @@ enum { #define NBD_FLAG_READ_ONLY (1 << 1) /* device is read-only */ #define NBD_FLAG_SEND_FLUSH (1 << 2) /* can flush writeback cache */ #define NBD_FLAG_SEND_FUA (1 << 3) /* send FUA (forced unit access) */ -/* there is a gap here to match userspace */ +#define NBD_FLAG_ROTATIONAL (1 << 4) /* device is rotational */ #define NBD_FLAG_SEND_TRIM (1 << 5) /* send trim/discard */ +/* there is a gap here to match userspace */ #define NBD_FLAG_CAN_MULTI_CONN (1 << 8) /* Server supports multiple connections per export. */ /* values for cmd flags in the upper 16 bits of request type */
The NBD protocol defines the flag NBD_FLAG_ROTATIONAL to flag that the export in use should be treated as a rotational device. Add support for that flag to the kernel driver. Signed-off-by: Wouter Verhelst <w@uter.be> --- drivers/block/nbd.c | 3 +++ include/uapi/linux/nbd.h | 3 ++- 2 files changed, 5 insertions(+), 1 deletion(-)