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virtio_blk: add discard and write zeroes support

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In commit 88c85538, "virtio-blk: add discard and write zeroes features
to specification" (https://github.com/oasis-tcs/virtio-spec), the virtio
block specification has been extended to add VIRTIO_BLK_T_DISCARD and
VIRTIO_BLK_T_WRITE_ZEROES commands.  This patch enables support for
discard and write zeroes in the virtio-blk driver when the device
advertises the corresponding features, VIRTIO_BLK_F_DISCARD and
VIRTIO_BLK_F_WRITE_ZEROES.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Changpeng Liu 2018-11-01 15:40:35 -07:00 • committed by Michael S. Tsirkin
parent c5c08bed84
commit 1f23816b8e
2 changed files with 135 additions and 2 deletions
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54
include/uapi/linux/virtio_blk.h
View file

@ -38,6 +38,8 @@
#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
#define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */
#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 */
/* Legacy feature bits */
#ifndef VIRTIO_BLK_NO_LEGACY
@ -86,6 +88,39 @@ struct virtio_blk_config {
/* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
__u16 num_queues;
/* the next 3 entries are guarded by VIRTIO_BLK_F_DISCARD */
/*
* The maximum discard sectors (in 512-byte sectors) for
* one segment.
*/
__u32 max_discard_sectors;
/*
* The maximum number of discard segments in a
* discard command.
*/
__u32 max_discard_seg;
/* Discard commands must be aligned to this number of sectors. */
__u32 discard_sector_alignment;
/* the next 3 entries are guarded by VIRTIO_BLK_F_WRITE_ZEROES */
/*
* The maximum number of write zeroes sectors (in 512-byte sectors) in
* one segment.
*/
__u32 max_write_zeroes_sectors;
/*
* The maximum number of segments in a write zeroes
* command.
*/
__u32 max_write_zeroes_seg;
/*
* Set if a VIRTIO_BLK_T_WRITE_ZEROES request may result in the
* deallocation of one or more of the sectors.
*/
__u8 write_zeroes_may_unmap;
__u8 unused1[3];
} __attribute__((packed));
/*
@ -114,6 +149,12 @@ struct virtio_blk_config {
/* Get device ID command */
#define VIRTIO_BLK_T_GET_ID 8
/* Discard command */
#define VIRTIO_BLK_T_DISCARD 11
/* Write zeroes command */
#define VIRTIO_BLK_T_WRITE_ZEROES 13
#ifndef VIRTIO_BLK_NO_LEGACY
/* Barrier before this op. */
#define VIRTIO_BLK_T_BARRIER 0x80000000
@ -133,6 +174,19 @@ struct virtio_blk_outhdr {
__virtio64 sector;
};
/* Unmap this range (only valid for write zeroes command) */
#define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP 0x00000001
/* Discard/write zeroes range for each request. */
struct virtio_blk_discard_write_zeroes {
/* discard/write zeroes start sector */
__le64 sector;
/* number of discard/write zeroes sectors */
__le32 num_sectors;
/* flags for this range */
__le32 flags;
};
#ifndef VIRTIO_BLK_NO_LEGACY
struct virtio_scsi_inhdr {
__virtio32 errors;