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Message-Id: <20211206145550.183263611@linuxfoundation.org>
Date: Mon, 6 Dec 2021 15:56:12 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Juergen Gross <jgross@...e.com>,
Jan Beulich <jbeulich@...e.com>,
Roger Pau Monné <roger.pau@...rix.com>
Subject: [PATCH 4.9 29/62] xen/blkfront: read response from backend only once
From: Juergen Gross <jgross@...e.com>
commit 71b66243f9898d0e54296b4e7035fb33cdcb0707 upstream.
In order to avoid problems in case the backend is modifying a response
on the ring page while the frontend has already seen it, just read the
response into a local buffer in one go and then operate on that buffer
only.
Signed-off-by: Juergen Gross <jgross@...e.com>
Reviewed-by: Jan Beulich <jbeulich@...e.com>
Acked-by: Roger Pau Monné <roger.pau@...rix.com>
Link: https://lore.kernel.org/r/20210730103854.12681-2-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/block/xen-blkfront.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1538,7 +1538,7 @@ static bool blkif_completion(unsigned lo
static irqreturn_t blkif_interrupt(int irq, void *dev_id)
{
struct request *req;
- struct blkif_response *bret;
+ struct blkif_response bret;
RING_IDX i, rp;
unsigned long flags;
struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
@@ -1556,8 +1556,9 @@ static irqreturn_t blkif_interrupt(int i
for (i = rinfo->ring.rsp_cons; i != rp; i++) {
unsigned long id;
- bret = RING_GET_RESPONSE(&rinfo->ring, i);
- id = bret->id;
+ RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
+ id = bret.id;
+
/*
* The backend has messed up and given us an id that we would
* never have given to it (we stamp it up to BLK_RING_SIZE -
@@ -1565,35 +1566,35 @@ static irqreturn_t blkif_interrupt(int i
*/
if (id >= BLK_RING_SIZE(info)) {
WARN(1, "%s: response to %s has incorrect id (%ld)\n",
- info->gd->disk_name, op_name(bret->operation), id);
+ info->gd->disk_name, op_name(bret.operation), id);
/* We can't safely get the 'struct request' as
* the id is busted. */
continue;
}
req = rinfo->shadow[id].request;
- if (bret->operation != BLKIF_OP_DISCARD) {
+ if (bret.operation != BLKIF_OP_DISCARD) {
/*
* We may need to wait for an extra response if the
* I/O request is split in 2
*/
- if (!blkif_completion(&id, rinfo, bret))
+ if (!blkif_completion(&id, rinfo, &bret))
continue;
}
if (add_id_to_freelist(rinfo, id)) {
WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
- info->gd->disk_name, op_name(bret->operation), id);
+ info->gd->disk_name, op_name(bret.operation), id);
continue;
}
- error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
- switch (bret->operation) {
+ error = (bret.status == BLKIF_RSP_OKAY) ? 0 : -EIO;
+ switch (bret.operation) {
case BLKIF_OP_DISCARD:
- if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
+ if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
struct request_queue *rq = info->rq;
printk(KERN_WARNING "blkfront: %s: %s op failed\n",
- info->gd->disk_name, op_name(bret->operation));
+ info->gd->disk_name, op_name(bret.operation));
error = -EOPNOTSUPP;
info->feature_discard = 0;
info->feature_secdiscard = 0;
@@ -1604,15 +1605,15 @@ static irqreturn_t blkif_interrupt(int i
break;
case BLKIF_OP_FLUSH_DISKCACHE:
case BLKIF_OP_WRITE_BARRIER:
- if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
+ if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
printk(KERN_WARNING "blkfront: %s: %s op failed\n",
- info->gd->disk_name, op_name(bret->operation));
+ info->gd->disk_name, op_name(bret.operation));
error = -EOPNOTSUPP;
}
- if (unlikely(bret->status == BLKIF_RSP_ERROR &&
+ if (unlikely(bret.status == BLKIF_RSP_ERROR &&
rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
- info->gd->disk_name, op_name(bret->operation));
+ info->gd->disk_name, op_name(bret.operation));
error = -EOPNOTSUPP;
}
if (unlikely(error)) {
@@ -1625,9 +1626,9 @@ static irqreturn_t blkif_interrupt(int i
/* fall through */
case BLKIF_OP_READ:
case BLKIF_OP_WRITE:
- if (unlikely(bret->status != BLKIF_RSP_OKAY))
+ if (unlikely(bret.status != BLKIF_RSP_OKAY))
dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
- "request: %x\n", bret->status);
+ "request: %x\n", bret.status);
blk_mq_complete_request(req, error);
break;
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