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xen: dont try setting max grants multiple times

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Trying to call xengnttab_set_max_grants() with the same file handle
might fail on some kernels, as this operation is allowed only once.

This is a problem for the qdisk backend as blk_connect() can be
called multiple times for a domain, e.g. in case grub-xen is being
used to boot it.

So instead of letting the generic backend code open the gnttab device
do it in blk_connect() and close it again in blk_disconnect.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
This commit is contained in:
Juergen Gross 2017-09-22 14:07:25 +02:00 committed by Stefano Stabellini
parent b5e397a79e
commit e38c3e86df
1 changed files with 12 additions and 4 deletions
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16
hw/block/xen_disk.c
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@ -1220,6 +1220,12 @@ static int blk_connect(struct XenDevice *xendev)
/* Add on the number needed for the ring pages */
max_grants += blkdev->nr_ring_ref;
blkdev->xendev.gnttabdev = xengnttab_open(NULL, 0);
if (blkdev->xendev.gnttabdev == NULL) {
xen_pv_printf(xendev, 0, "xengnttab_open failed: %s\n",
strerror(errno));
return -1;
}
if (xengnttab_set_max_grants(blkdev->xendev.gnttabdev, max_grants)) {
xen_pv_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
strerror(errno));
@ -1327,6 +1333,11 @@ static void blk_disconnect(struct XenDevice *xendev)
}
blkdev->feature_persistent = false;
}
if (blkdev->xendev.gnttabdev) {
xengnttab_close(blkdev->xendev.gnttabdev);
blkdev->xendev.gnttabdev = NULL;
}
}
static int blk_free(struct XenDevice *xendev)
@ -1334,9 +1345,7 @@ static int blk_free(struct XenDevice *xendev)
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
struct ioreq *ioreq;
if (blkdev->blk || blkdev->sring) {
blk_disconnect(xendev);
}
blk_disconnect(xendev);
while (!QLIST_EMPTY(&blkdev->freelist)) {
ioreq = QLIST_FIRST(&blkdev->freelist);
@ -1363,7 +1372,6 @@ static void blk_event(struct XenDevice *xendev)
struct XenDevOps xen_blkdev_ops = {
.size = sizeof(struct XenBlkDev),
.flags = DEVOPS_FLAG_NEED_GNTDEV,
.alloc = blk_alloc,
.init = blk_init,
.initialise = blk_connect,