diff options
| author | Konrad Rzeszutek Wilk | 2011-10-10 06:42:22 +0200 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk | 2011-10-13 15:48:36 +0200 |
| commit | 29bde093787f3bdf7b9b4270ada6be7c8076e36b (patch) | |
| tree | 4fff697e0acb2471b1bd575cbd006fa4efc3937d /drivers/block/xen-blkback/xenbus.c | |
| parent | xen-blkfront: plug device number leak in xlblk_init() error path (diff) | |
| download | kernel-qcow2-linux-29bde093787f3bdf7b9b4270ada6be7c8076e36b.tar.gz kernel-qcow2-linux-29bde093787f3bdf7b9b4270ada6be7c8076e36b.tar.xz kernel-qcow2-linux-29bde093787f3bdf7b9b4270ada6be7c8076e36b.zip | |
xen/blkback: Support 'feature-barrier' aka old-style BARRIER requests.
We emulate the barrier requests by draining the outstanding bio's
and then sending the WRITE_FLUSH command. To drain the I/Os
we use the refcnt that is used during disconnect to wait for all
the I/Os before disconnecting from the frontend. We latch on its
value and if it reaches either the threshold for disconnect or when
there are no more outstanding I/Os, then we have drained all I/Os.
Suggested-by: Christopher Hellwig <hch@infradead.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/block/xen-blkback/xenbus.c')
| -rw-r--r-- | drivers/block/xen-blkback/xenbus.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index 1c44b3254134..a6d43030b107 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -114,6 +114,8 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid) spin_lock_init(&blkif->blk_ring_lock); atomic_set(&blkif->refcnt, 1); init_waitqueue_head(&blkif->wq); + init_completion(&blkif->drain_complete); + atomic_set(&blkif->drain, 0); blkif->st_print = jiffies; init_waitqueue_head(&blkif->waiting_to_free); @@ -474,6 +476,19 @@ kfree: out: return err; } +int xen_blkbk_barrier(struct xenbus_transaction xbt, + struct backend_info *be, int state) +{ + struct xenbus_device *dev = be->dev; + int err; + + err = xenbus_printf(xbt, dev->nodename, "feature-barrier", + "%d", state); + if (err) + xenbus_dev_fatal(dev, err, "writing feature-barrier"); + + return err; +} /* * Entry point to this code when a new device is created. Allocate the basic @@ -708,6 +723,9 @@ again: err = xen_blkbk_discard(xbt, be); + /* If we can't advertise it is OK. */ + err = xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); + err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", (unsigned long long)vbd_sz(&be->blkif->vbd)); if (err) { |