[Qemu-devel] [PATCH 0/3] virtio-blk: rerror/werror fixes (including corruption fix)

[Qemu-devel] [PATCH 0/3] virtio-blk: rerror/werror fixes (including corruption fix)

[Kevin Wolf]

This fixes two bugs in the handling of rerror/werror in virtio-blk. First is a
fix for read requests morphing into write requests after the VM was stopped by
a read error. Second is to consider rerror/werror in places where virtio-blk
used to directly report errors back.

This series should be applied to stable as well.

Kevin Wolf (3):
  virtio_blk: Factor virtio_blk_handle_request out
  virtio-blk: Fix restart after read error
  virtio-blk: Fix error cases which ignored rerror/werror

 hw/virtio-blk.c |   93 +++++++++++++++++++++++++++++++++---------------------
 1 files changed, 57 insertions(+), 36 deletions(-)

[Qemu-devel] [PATCH 1/3] virtio_blk: Factor virtio_blk_handle_request out

[Kevin Wolf]

We need a function that handles a single request. Create one by splitting out
code from virtio_blk_handle_output.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/virtio-blk.c |   78 ++++++++++++++++++++++++++++++++----------------------
 1 files changed, 46 insertions(+), 32 deletions(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 865352a..82f96e5 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -317,46 +317,60 @@ static void virtio_blk_handle_read(VirtIOBlockReq *req)
     }
 }
 
+typedef struct MultiReqBuffer {
+    BlockRequest        blkreq[32];
+    int                 num_writes;
+    BlockDriverState    *old_bs;
+} MultiReqBuffer;
+
+static void virtio_blk_handle_request(VirtIOBlockReq *req,
+    MultiReqBuffer *mrb)
+{
+    if (req->elem.out_num < 1 || req->elem.in_num < 1) {
+        fprintf(stderr, "virtio-blk missing headers\n");
+        exit(1);
+    }
+
+    if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
+        req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
+        fprintf(stderr, "virtio-blk header not in correct element\n");
+        exit(1);
+    }
+
+    req->out = (void *)req->elem.out_sg[0].iov_base;
+    req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
+
+    if (req->out->type & VIRTIO_BLK_T_FLUSH) {
+        virtio_blk_handle_flush(req);
+    } else if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
+        virtio_blk_handle_scsi(req);
+    } else if (req->out->type & VIRTIO_BLK_T_OUT) {
+        qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
+                                 req->elem.out_num - 1);
+        virtio_blk_handle_write(mrb->blkreq, &mrb->num_writes,
+            req, &mrb->old_bs);
+    } else {
+        qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
+                                 req->elem.in_num - 1);
+        virtio_blk_handle_read(req);
+    }
+}
+
 static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBlock *s = to_virtio_blk(vdev);
     VirtIOBlockReq *req;
-    BlockRequest blkreq[32];
-    int num_writes = 0;
-    BlockDriverState *old_bs = NULL;
+    MultiReqBuffer mrb = {
+        .num_writes = 0,
+        .old_bs = NULL,
+    };
 
     while ((req = virtio_blk_get_request(s))) {
-        if (req->elem.out_num < 1 || req->elem.in_num < 1) {
-            fprintf(stderr, "virtio-blk missing headers\n");
-            exit(1);
-        }
-
-        if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
-            req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
-            fprintf(stderr, "virtio-blk header not in correct element\n");
-            exit(1);
-        }
-
-        req->out = (void *)req->elem.out_sg[0].iov_base;
-        req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
-
-        if (req->out->type & VIRTIO_BLK_T_FLUSH) {
-            virtio_blk_handle_flush(req);
-        } else if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
-            virtio_blk_handle_scsi(req);
-        } else if (req->out->type & VIRTIO_BLK_T_OUT) {
-            qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
-                                     req->elem.out_num - 1);
-            virtio_blk_handle_write(blkreq, &num_writes, req, &old_bs);
-        } else {
-            qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
-                                     req->elem.in_num - 1);
-            virtio_blk_handle_read(req);
-        }
+        virtio_blk_handle_request(req, &mrb);
     }
 
-    if (num_writes > 0) {
-        do_multiwrite(old_bs, blkreq, num_writes);
+    if (mrb.num_writes > 0) {
+        do_multiwrite(mrb.old_bs, mrb.blkreq, mrb.num_writes);
     }
 
     /*
-- 
1.6.5.2

[Qemu-devel] Re: [PATCH 1/3] virtio_blk: Factor virtio_blk_handle_request out

[Christoph Hellwig]

On Wed, Jan 27, 2010 at 01:12:34PM +0100, Kevin Wolf wrote:
> We need a function that handles a single request. Create one by splitting out
> code from virtio_blk_handle_output.

Looks good,


Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [Qemu-devel] [PATCH 1/3] virtio_blk: Factor virtio_blk_handle_request out

[Anthony Liguori]

On 01/27/2010 06:12 AM, Kevin Wolf wrote:
> We need a function that handles a single request. Create one by splitting out
> code from virtio_blk_handle_output.
>
> Signed-off-by: Kevin Wolf<kwolf@redhat.com>
>    

Applied all.  Thanks.

Regards,

Anthony Liguori

> ---
>   hw/virtio-blk.c |   78 ++++++++++++++++++++++++++++++++----------------------
>   1 files changed, 46 insertions(+), 32 deletions(-)
>
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index 865352a..82f96e5 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -317,46 +317,60 @@ static void virtio_blk_handle_read(VirtIOBlockReq *req)
>       }
>   }
>
> +typedef struct MultiReqBuffer {
> +    BlockRequest        blkreq[32];
> +    int                 num_writes;
> +    BlockDriverState    *old_bs;
> +} MultiReqBuffer;
> +
> +static void virtio_blk_handle_request(VirtIOBlockReq *req,
> +    MultiReqBuffer *mrb)
> +{
> +    if (req->elem.out_num<  1 || req->elem.in_num<  1) {
> +        fprintf(stderr, "virtio-blk missing headers\n");
> +        exit(1);
> +    }
> +
> +    if (req->elem.out_sg[0].iov_len<  sizeof(*req->out) ||
> +        req->elem.in_sg[req->elem.in_num - 1].iov_len<  sizeof(*req->in)) {
> +        fprintf(stderr, "virtio-blk header not in correct element\n");
> +        exit(1);
> +    }
> +
> +    req->out = (void *)req->elem.out_sg[0].iov_base;
> +    req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
> +
> +    if (req->out->type&  VIRTIO_BLK_T_FLUSH) {
> +        virtio_blk_handle_flush(req);
> +    } else if (req->out->type&  VIRTIO_BLK_T_SCSI_CMD) {
> +        virtio_blk_handle_scsi(req);
> +    } else if (req->out->type&  VIRTIO_BLK_T_OUT) {
> +        qemu_iovec_init_external(&req->qiov,&req->elem.out_sg[1],
> +                                 req->elem.out_num - 1);
> +        virtio_blk_handle_write(mrb->blkreq,&mrb->num_writes,
> +            req,&mrb->old_bs);
> +    } else {
> +        qemu_iovec_init_external(&req->qiov,&req->elem.in_sg[0],
> +                                 req->elem.in_num - 1);
> +        virtio_blk_handle_read(req);
> +    }
> +}
> +
>   static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>   {
>       VirtIOBlock *s = to_virtio_blk(vdev);
>       VirtIOBlockReq *req;
> -    BlockRequest blkreq[32];
> -    int num_writes = 0;
> -    BlockDriverState *old_bs = NULL;
> +    MultiReqBuffer mrb = {
> +        .num_writes = 0,
> +        .old_bs = NULL,
> +    };
>
>       while ((req = virtio_blk_get_request(s))) {
> -        if (req->elem.out_num<  1 || req->elem.in_num<  1) {
> -            fprintf(stderr, "virtio-blk missing headers\n");
> -            exit(1);
> -        }
> -
> -        if (req->elem.out_sg[0].iov_len<  sizeof(*req->out) ||
> -            req->elem.in_sg[req->elem.in_num - 1].iov_len<  sizeof(*req->in)) {
> -            fprintf(stderr, "virtio-blk header not in correct element\n");
> -            exit(1);
> -        }
> -
> -        req->out = (void *)req->elem.out_sg[0].iov_base;
> -        req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
> -
> -        if (req->out->type&  VIRTIO_BLK_T_FLUSH) {
> -            virtio_blk_handle_flush(req);
> -        } else if (req->out->type&  VIRTIO_BLK_T_SCSI_CMD) {
> -            virtio_blk_handle_scsi(req);
> -        } else if (req->out->type&  VIRTIO_BLK_T_OUT) {
> -            qemu_iovec_init_external(&req->qiov,&req->elem.out_sg[1],
> -                                     req->elem.out_num - 1);
> -            virtio_blk_handle_write(blkreq,&num_writes, req,&old_bs);
> -        } else {
> -            qemu_iovec_init_external(&req->qiov,&req->elem.in_sg[0],
> -                                     req->elem.in_num - 1);
> -            virtio_blk_handle_read(req);
> -        }
> +        virtio_blk_handle_request(req,&mrb);
>       }
>
> -    if (num_writes>  0) {
> -        do_multiwrite(old_bs, blkreq, num_writes);
> +    if (mrb.num_writes>  0) {
> +        do_multiwrite(mrb.old_bs, mrb.blkreq, mrb.num_writes);
>       }
>
>       /*
>    

[Qemu-devel] [PATCH 2/3] virtio-blk: Fix restart after read error

[Kevin Wolf]

Current code assumes that only write requests are ever going to be restarted.
This is wrong since rerror=stop exists. Instead of directly starting writes,
use the same request processing as used for new requests.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/virtio-blk.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 82f96e5..5a413b9 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -384,6 +384,10 @@ static void virtio_blk_dma_restart_bh(void *opaque)
 {
     VirtIOBlock *s = opaque;
     VirtIOBlockReq *req = s->rq;
+    MultiReqBuffer mrb = {
+        .num_writes = 0,
+        .old_bs = NULL,
+    };
 
     qemu_bh_delete(s->bh);
     s->bh = NULL;
@@ -391,10 +395,13 @@ static void virtio_blk_dma_restart_bh(void *opaque)
     s->rq = NULL;
 
     while (req) {
-        bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
-            req->qiov.size / 512, virtio_blk_rw_complete, req);
+        virtio_blk_handle_request(req, &mrb);
         req = req->next;
     }
+
+    if (mrb.num_writes > 0) {
+        do_multiwrite(mrb.old_bs, mrb.blkreq, mrb.num_writes);
+    }
 }
 
 static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)
-- 
1.6.5.2

[Qemu-devel] Re: [PATCH 2/3] virtio-blk: Fix restart after read error

[Christoph Hellwig]

On Wed, Jan 27, 2010 at 01:12:35PM +0100, Kevin Wolf wrote:
> Current code assumes that only write requests are ever going to be restarted.
> This is wrong since rerror=stop exists. Instead of directly starting writes,
> use the same request processing as used for new requests.

Looks good,


Reviewed-by: Christoph Hellwig <hch@lst.de>

[Qemu-devel] [PATCH 3/3] virtio-blk: Fix error cases which ignored rerror/werror

[Kevin Wolf]

If an I/O request fails right away instead of getting an error only in the
callback, we still need to consider rerror/werror.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/virtio-blk.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 5a413b9..037a79c 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -269,7 +269,7 @@ static void do_multiwrite(BlockDriverState *bs, BlockRequest *blkreq,
     if (ret != 0) {
         for (i = 0; i < num_writes; i++) {
             if (blkreq[i].error) {
-                virtio_blk_req_complete(blkreq[i].opaque, VIRTIO_BLK_S_IOERR);
+                virtio_blk_rw_complete(blkreq[i].opaque, -EIO);
             }
         }
     }
@@ -313,7 +313,7 @@ static void virtio_blk_handle_read(VirtIOBlockReq *req)
     acb = bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov,
                          req->qiov.size / 512, virtio_blk_rw_complete, req);
     if (!acb) {
-        virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
+        virtio_blk_rw_complete(req, -EIO);
     }
 }
 
-- 
1.6.5.2

[Qemu-devel] Re: [PATCH 3/3] virtio-blk: Fix error cases which ignored rerror/werror

[Christoph Hellwig]

On Wed, Jan 27, 2010 at 01:12:36PM +0100, Kevin Wolf wrote:
> If an I/O request fails right away instead of getting an error only in the
> callback, we still need to consider rerror/werror.

Looks good,


Reviewed-by: Christoph Hellwig <hch@lst.de>