在 2021/7/15 下午5:47, Yury Kamenev 写道:
Signed-off-by: Yury Kamenev <[email protected]>
I think we need a better commit log here.
And why do we need a Kconfig for this? If there's a good reason, I guess
the right approach is to invent something in the virtio core (via /sys)?
Thanks
---
.../admin-guide/kernel-parameters.txt | 3 +++
drivers/block/Kconfig | 7 +++++
drivers/block/virtio_blk.c | 26 +++++++++++++++++++
include/uapi/linux/virtio_blk.h | 2 ++
4 files changed, 38 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index bdb22006f713..941bdaf5c167 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6076,6 +6076,9 @@
brightness level.
default: 1
+ virtiopartscan
+ Enable virtio block device partition scanning omission based on
VIRTIO_BLK_F_NO_PART_SCAN feature flag.
+
virtio_mmio.device=
[VMMIO] Memory mapped virtio (platform) device.
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 63056cfd4b62..69ecd3fd7037 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -399,6 +399,13 @@ config VIRTIO_BLK
This is the virtual block driver for virtio. It can be used with
QEMU based VMMs (like KVM or Xen). Say Y or M.
+config VIRTIO_BLK_NO_PART_SCAN
+ bool "Disable partition scanning for devices with no partitions"
+ depends on VIRTIO_BLK
+ help
+ Disable partition scanning for devices with no partitions.
+ Can reduce the kernel start time for tiny systems like squashfs
images.
+
config BLK_DEV_RBD
tristate "Rados block device (RBD)"
depends on INET && BLOCK
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 4b49df2dfd23..479711d3791c 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -692,6 +692,19 @@ static const struct blk_mq_ops virtio_mq_ops = {
static unsigned int virtblk_queue_depth;
module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
+#ifndef MODULE
+#ifdef CONFIG_VIRTIO_BLK_NO_PART_SCAN
+static int partitions_scanning_disable __read_mostly;
+
+static int __init partitions_scanning_setup(char *__unused)
+{
+ partitions_scanning_disable = 1;
+ return 1;
+}
+__setup("nopartscan", partitions_scanning_setup);
+#endif
+#endif
+
static int virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
@@ -790,6 +803,13 @@ static int virtblk_probe(struct virtio_device *vdev)
vblk->disk->flags |= GENHD_FL_EXT_DEVT;
vblk->index = index;
+#ifdef CONFIG_VIRTIO_BLK_NO_PART_SCAN
+ if (unlikely(partitions_scanning_disable))
+ /* disable partitions scanning if it was stated in virtio
features*/
+ if (virtio_has_feature(vdev, VIRTIO_BLK_F_NO_PART_SCAN))
+ vblk->disk->flags |= GENHD_FL_NO_PART_SCAN;
+#endif
+
/* configure queue flush support */
virtblk_update_cache_mode(vdev);
@@ -966,6 +986,9 @@ static unsigned int features_legacy[] = {
VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
+#ifdef CONFIG_VIRTIO_BLK_NO_PART_SCAN
+ VIRTIO_BLK_F_NO_PART_SCAN,
+#endif
}
;
static unsigned int features[] = {
@@ -973,6 +996,9 @@ static unsigned int features[] = {
VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
+#ifdef CONFIG_VIRTIO_BLK_NO_PART_SCAN
+ VIRTIO_BLK_F_NO_PART_SCAN,
+#endif
};
static struct virtio_driver virtio_blk = {
diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
index d888f013d9ff..9b381675342a 100644
--- a/include/uapi/linux/virtio_blk.h
+++ b/include/uapi/linux/virtio_blk.h
@@ -40,6 +40,7 @@
#define VIRTIO_BLK_F_MQ 12 /* support more than one vq */
#define VIRTIO_BLK_F_DISCARD 13 /* DISCARD is supported */
#define VIRTIO_BLK_F_WRITE_ZEROES 14 /* WRITE ZEROES is supported */
+#define VIRTIO_BLK_F_NO_PART_SCAN 16 /* Disable partition scanning */
/* Legacy feature bits */
#ifndef VIRTIO_BLK_NO_LEGACY
--
2.24.3 (Apple Git-128)
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