rpms/kernel/F-12 linux-2.6-virtio_blk-add-support-for-cache-flush.patch, NONE, 1.1 kernel.spec, 1.1844, 1.1845

[Justin M. Forbes]

Author: jforbes

Update of /cvs/pkgs/rpms/kernel/F-12
In directory cvs1.fedora.phx.redhat.com:/tmp/cvs-serv32612

Modified Files:
	kernel.spec 
Added Files:
	linux-2.6-virtio_blk-add-support-for-cache-flush.patch 
Log Message:
virtio_blk: add support for cache flush (#526869)

linux-2.6-virtio_blk-add-support-for-cache-flush.patch:
 drivers/block/virtio_blk.c |   30 +++++++++++++++++++++++++-----
 include/linux/virtio_blk.h |   15 +++++++++++++++
 2 files changed, 40 insertions(+), 5 deletions(-)

--- NEW FILE linux-2.6-virtio_blk-add-support-for-cache-flush.patch ---
From: Christoph Hellwig <hch at lst.de>
Date: Thu, 17 Sep 2009 17:57:42 +0000 (+0200)
Subject: virtio_blk: add support for cache flush
X-Git-Tag: v2.6.32-rc1~175^2~5
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=f1b0ef0626

virtio_blk: add support for cache flush

Recent qemu has added a VIRTIO_BLK_F_FLUSH flag to advertise that the
virtual disk has a volatile write cache that needs to be flushed.  In case
we see this feature implement tell the Linux block layer about the fact
and use the new VIRTIO_BLK_T_FLUSH to flush the cache when required.  This
allows for an correct and simple implementation of write barriers.

Signed-off-by: Christoph Hellwig <hch at lst.de>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
---

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 73de753..3d5fe97 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -92,15 +92,26 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
 		return false;
 
 	vbr->req = req;
-	if (blk_fs_request(vbr->req)) {
+	switch (req->cmd_type) {
+	case REQ_TYPE_FS:
 		vbr->out_hdr.type = 0;
 		vbr->out_hdr.sector = blk_rq_pos(vbr->req);
 		vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
-	} else if (blk_pc_request(vbr->req)) {
+		break;
+	case REQ_TYPE_BLOCK_PC:
 		vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
 		vbr->out_hdr.sector = 0;
 		vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
-	} else {
+		break;
+	case REQ_TYPE_LINUX_BLOCK:
+		if (req->cmd[0] == REQ_LB_OP_FLUSH) {
+			vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
+			vbr->out_hdr.sector = 0;
+			vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
+			break;
+		}
+		/*FALLTHRU*/
+	default:
 		/* We don't put anything else in the queue. */
 		BUG();
 	}
@@ -200,6 +211,12 @@ out:
 	return err;
 }
 
+static void virtblk_prepare_flush(struct request_queue *q, struct request *req)
+{
+	req->cmd_type = REQ_TYPE_LINUX_BLOCK;
+	req->cmd[0] = REQ_LB_OP_FLUSH;
+}
+
 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
 			 unsigned cmd, unsigned long data)
 {
@@ -338,7 +355,10 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
 	index++;
 
 	/* If barriers are supported, tell block layer that queue is ordered */
-	if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
+	if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
+		blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_DRAIN_FLUSH,
+				  virtblk_prepare_flush);
+	else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
 		blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
 
 	/* If disk is read-only in the host, the guest should obey */
@@ -425,7 +445,7 @@ static struct virtio_device_id id_table[] = {
 static unsigned int features[] = {
 	VIRTIO_BLK_F_BARRIER, 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_IDENTIFY
+	VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_IDENTIFY, VIRTIO_BLK_F_FLUSH
 };
 
 /*
diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index 25fbabf..15cb666 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -14,6 +14,7 @@
 #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_IDENTIFY	8	/* ATA IDENTIFY supported */
+#define VIRTIO_BLK_F_FLUSH	9	/* Cache flush command support */
 
 #define VIRTIO_BLK_ID_BYTES	(sizeof(__u16[256]))	/* IDENTIFY DATA */
 
@@ -35,6 +36,17 @@ struct virtio_blk_config {
 	__u8 identify[VIRTIO_BLK_ID_BYTES];
 } __attribute__((packed));
 
+/*
+ * Command types
+ *
+ * Usage is a bit tricky as some bits are used as flags and some are not.
+ *
+ * Rules:
+ *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
+ *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
+ *   and may not be combined with any of the other flags.
+ */
+
 /* These two define direction. */
 #define VIRTIO_BLK_T_IN		0
 #define VIRTIO_BLK_T_OUT	1
@@ -42,6 +54,9 @@ struct virtio_blk_config {
 /* This bit says it's a scsi command, not an actual read or write. */
 #define VIRTIO_BLK_T_SCSI_CMD	2
 
+/* Cache flush command */
+#define VIRTIO_BLK_T_FLUSH	4
+
 /* Barrier before this op. */
 #define VIRTIO_BLK_T_BARRIER	0x80000000
 


Index: kernel.spec
===================================================================
RCS file: /cvs/pkgs/rpms/kernel/F-12/kernel.spec,v
retrieving revision 1.1844
retrieving revision 1.1845
diff -u -p -r1.1844 -r1.1845
--- kernel.spec	2 Oct 2009 20:07:35 -0000	1.1844
+++ kernel.spec	6 Oct 2009 14:44:42 -0000	1.1845
@@ -703,6 +703,7 @@ Patch1582: linux-2.6-xen-spinlock-strong
 Patch1583: linux-2.6-xen-fix-is_disconnected_device-exists_disconnected_device.patch
 Patch1584: linux-2.6-xen-improvement-to-wait_for_devices.patch
 Patch1585: linux-2.6-xen-increase-device-connection-timeout.patch
+Patch1586: linux-2.6-virtio_blk-add-support-for-cache-flush.patch
 
 # nouveau + drm fixes
 Patch1812: drm-next-4c57edba4.patch
@@ -1370,6 +1371,7 @@ ApplyPatch linux-2.6-xen-check-efer-fix.
 ApplyPatch linux-2.6-xen-fix-is_disconnected_device-exists_disconnected_device.patch
 ApplyPatch linux-2.6-xen-improvement-to-wait_for_devices.patch
 ApplyPatch linux-2.6-xen-increase-device-connection-timeout.patch
+ApplyPatch linux-2.6-virtio_blk-add-support-for-cache-flush.patch
 
 # improve xen spinlock scalability
 ApplyPatch linux-2.6-xen-spinlock-enable-interrupts-only-when-blocking.patch
@@ -2077,6 +2079,9 @@ fi
 # and build.
 
 %changelog
+* Tue Oct  6 2009 Justin M. Forbes <jforbes at redhat.com>
+- virtio_blk: add support for cache flush (#526869)
+
 * Fri Oct  2 2009 John W. Linville <linville at redhat.com>
 - Backport "iwlwifi: reduce noise when skb allocation fails"