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xen/blkback: disable discard feature if requested by toolstack

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Newer toolstacks may provide a boolean property "discard-enable" in the
backend node. Its purpose is to disable discard for file backed storage
to avoid fragmentation. Recognize this setting also for physical
storage.  If that property exists and is false, do not advertise
"feature-discard" to the frontend.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Olaf Hering 2014-05-21 16:32:42 +02:00 committed by Konrad Rzeszutek Wilk
parent 1c8cad6c1b
commit c926b701fe
1 changed files with 6 additions and 1 deletions
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7
drivers/block/xen-blkback/xenbus.c
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@ -481,10 +481,15 @@ static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info
struct xenbus_device *dev = be->dev;
struct xen_blkif *blkif = be->blkif;
int err;
int state = 0;
int state = 0, discard_enable;
struct block_device *bdev = be->blkif->vbd.bdev;
struct request_queue *q = bdev_get_queue(bdev);
err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d",
&discard_enable);
if (err == 1 && !discard_enable)
return;
if (blk_queue_discard(q)) {
err = xenbus_printf(xbt, dev->nodename,
"discard-granularity", "%u",