From ddcc286900732953ac2e950b6ad0f9a4933767fb Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Mon, 28 May 2012 12:18:39 +0530 Subject: virtio ids: fix comment for virtio-rng It's virtio-rng, not virtio-ring. Signed-off-by: Amit Shah Signed-off-by: Rusty Russell --- include/linux/virtio_ids.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/virtio_ids.h b/include/linux/virtio_ids.h index 7529b854b7fd..270fb22c5811 100644 --- a/include/linux/virtio_ids.h +++ b/include/linux/virtio_ids.h @@ -32,7 +32,7 @@ #define VIRTIO_ID_NET 1 /* virtio net */ #define VIRTIO_ID_BLOCK 2 /* virtio block */ #define VIRTIO_ID_CONSOLE 3 /* virtio console */ -#define VIRTIO_ID_RNG 4 /* virtio ring */ +#define VIRTIO_ID_RNG 4 /* virtio rng */ #define VIRTIO_ID_BALLOON 5 /* virtio balloon */ #define VIRTIO_ID_RPMSG 7 /* virtio remote processor messaging */ #define VIRTIO_ID_SCSI 8 /* virtio scsi */ -- cgit v1.2.3 From cd5d503862b0d0d927c56ef2e34d3ededac88039 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 3 Jul 2012 15:19:37 +0200 Subject: virtio-blk: allow toggling host cache between writeback and writethrough This patch adds support for the new VIRTIO_BLK_F_CONFIG_WCE feature, which exposes the cache mode in the configuration space and lets the driver modify it. The cache mode is exposed via sysfs. Even if the host does not support the new feature, the cache mode is visible (thanks to the existing VIRTIO_BLK_F_WCE), but not modifiable. Signed-off-by: Paolo Bonzini Signed-off-by: Rusty Russell --- drivers/block/virtio_blk.c | 90 ++++++++++++++++++++++++++++++++++++++++++++-- include/linux/virtio_blk.h | 5 ++- 2 files changed, 91 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 774c31dce7c0..c0bbeb470754 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -395,6 +395,83 @@ static int virtblk_name_format(char *prefix, int index, char *buf, int buflen) return 0; } +static int virtblk_get_cache_mode(struct virtio_device *vdev) +{ + u8 writeback; + int err; + + err = virtio_config_val(vdev, VIRTIO_BLK_F_CONFIG_WCE, + offsetof(struct virtio_blk_config, wce), + &writeback); + if (err) + writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE); + + return writeback; +} + +static void virtblk_update_cache_mode(struct virtio_device *vdev) +{ + u8 writeback = virtblk_get_cache_mode(vdev); + struct virtio_blk *vblk = vdev->priv; + + if (writeback) + blk_queue_flush(vblk->disk->queue, REQ_FLUSH); + else + blk_queue_flush(vblk->disk->queue, 0); + + revalidate_disk(vblk->disk); +} + +static const char *const virtblk_cache_types[] = { + "write through", "write back" +}; + +static ssize_t +virtblk_cache_type_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct gendisk *disk = dev_to_disk(dev); + struct virtio_blk *vblk = disk->private_data; + struct virtio_device *vdev = vblk->vdev; + int i; + u8 writeback; + + BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE)); + for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; ) + if (sysfs_streq(buf, virtblk_cache_types[i])) + break; + + if (i < 0) + return -EINVAL; + + writeback = i; + vdev->config->set(vdev, + offsetof(struct virtio_blk_config, wce), + &writeback, sizeof(writeback)); + + virtblk_update_cache_mode(vdev); + return count; +} + +static ssize_t +virtblk_cache_type_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct gendisk *disk = dev_to_disk(dev); + struct virtio_blk *vblk = disk->private_data; + u8 writeback = virtblk_get_cache_mode(vblk->vdev); + + BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types)); + return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]); +} + +static const struct device_attribute dev_attr_cache_type_ro = + __ATTR(cache_type, S_IRUGO, + virtblk_cache_type_show, NULL); +static const struct device_attribute dev_attr_cache_type_rw = + __ATTR(cache_type, S_IRUGO|S_IWUSR, + virtblk_cache_type_show, virtblk_cache_type_store); + static int __devinit virtblk_probe(struct virtio_device *vdev) { struct virtio_blk *vblk; @@ -471,8 +548,7 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) vblk->index = index; /* configure queue flush support */ - if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) - blk_queue_flush(q, REQ_FLUSH); + virtblk_update_cache_mode(vdev); /* If disk is read-only in the host, the guest should obey */ if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) @@ -550,6 +626,14 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) if (err) goto out_del_disk; + if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE)) + err = device_create_file(disk_to_dev(vblk->disk), + &dev_attr_cache_type_rw); + else + err = device_create_file(disk_to_dev(vblk->disk), + &dev_attr_cache_type_ro); + if (err) + goto out_del_disk; return 0; out_del_disk: @@ -642,7 +726,7 @@ static const struct virtio_device_id id_table[] = { static unsigned int features[] = { VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI, - VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY + VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE }; /* diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h index e0edb40ca7aa..e2aba15f545d 100644 --- a/include/linux/virtio_blk.h +++ b/include/linux/virtio_blk.h @@ -37,8 +37,9 @@ #define VIRTIO_BLK_F_RO 5 /* Disk is read-only */ #define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/ #define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */ -#define VIRTIO_BLK_F_FLUSH 9 /* Cache flush command support */ +#define VIRTIO_BLK_F_WCE 9 /* Writeback mode enabled after reset */ #define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */ +#define VIRTIO_BLK_F_CONFIG_WCE 11 /* Writeback mode available in config */ #define VIRTIO_BLK_ID_BYTES 20 /* ID string length */ @@ -69,6 +70,8 @@ struct virtio_blk_config { /* optimal sustained I/O size in logical blocks. */ __u32 opt_io_size; + /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */ + __u8 wce; } __attribute__((packed)); /* -- cgit v1.2.3 From 6a743897144500fb4c4566ced3a498d5180fbb5b Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 30 Jul 2012 13:30:52 +0930 Subject: virtio-blk: return VIRTIO_BLK_F_FLUSH to header. This got renamed and clarified, but let's not break any userspace out there. Signed-off-by: Rusty Russell --- include/linux/virtio_blk.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h index e2aba15f545d..6d8e61c48563 100644 --- a/include/linux/virtio_blk.h +++ b/include/linux/virtio_blk.h @@ -41,6 +41,11 @@ #define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */ #define VIRTIO_BLK_F_CONFIG_WCE 11 /* Writeback mode available in config */ +#ifndef __KERNEL__ +/* Old (deprecated) name for VIRTIO_BLK_F_WCE. */ +#define VIRTIO_BLK_F_FLUSH VIRTIO_BLK_F_WCE +#endif + #define VIRTIO_BLK_ID_BYTES 20 /* ID string length */ struct virtio_blk_config { -- cgit v1.2.3