From f023f18ddf41dda487241d1514075b1136eb8101 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Wed, 5 Apr 2017 12:03:59 -0700 Subject: [PATCH] xen/9pfs: send requests to the backend Implement struct p9_trans_module create and close functions by looking at the available Xen 9pfs frontend-backend connections. We don't expect many frontend-backend connections, thus walking a list is OK. Send requests to the backend by copying each request to one of the available rings (each frontend-backend connection comes with multiple rings). Handle the ring and notifications following the 9pfs specification. If there are not enough free bytes on the ring for the request, wait on the wait_queue: the backend will send a notification after consuming more requests. CC: groug@kaod.org CC: jgross@suse.com CC: Eric Van Hensbergen CC: Ron Minnich CC: Latchesar Ionkov CC: v9fs-developer@lists.sourceforge.net Signed-off-by: Stefano Stabellini Reviewed-by: Boris Ostrovsky Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- net/9p/trans_xen.c | 87 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 85 insertions(+), 2 deletions(-) diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index fe3d172391c4a..28f30f49d5dd2 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -85,22 +85,105 @@ struct xen_9pfs_front_priv { static LIST_HEAD(xen_9pfs_devs); static DEFINE_RWLOCK(xen_9pfs_lock); +/* We don't currently allow canceling of requests */ static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req) { - return 0; + return 1; } static int p9_xen_create(struct p9_client *client, const char *addr, char *args) { - return 0; + struct xen_9pfs_front_priv *priv; + + read_lock(&xen_9pfs_lock); + list_for_each_entry(priv, &xen_9pfs_devs, list) { + if (!strcmp(priv->tag, addr)) { + priv->client = client; + read_unlock(&xen_9pfs_lock); + return 0; + } + } + read_unlock(&xen_9pfs_lock); + return -EINVAL; } static void p9_xen_close(struct p9_client *client) { + struct xen_9pfs_front_priv *priv; + + read_lock(&xen_9pfs_lock); + list_for_each_entry(priv, &xen_9pfs_devs, list) { + if (priv->client == client) { + priv->client = NULL; + read_unlock(&xen_9pfs_lock); + return; + } + } + read_unlock(&xen_9pfs_lock); +} + +static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size) +{ + RING_IDX cons, prod; + + cons = ring->intf->out_cons; + prod = ring->intf->out_prod; + virt_mb(); + + return XEN_9PFS_RING_SIZE - + xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) >= size; } static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) { + struct xen_9pfs_front_priv *priv = NULL; + RING_IDX cons, prod, masked_cons, masked_prod; + unsigned long flags; + u32 size = p9_req->tc->size; + struct xen_9pfs_dataring *ring; + int num; + + read_lock(&xen_9pfs_lock); + list_for_each_entry(priv, &xen_9pfs_devs, list) { + if (priv->client == client) + break; + } + read_unlock(&xen_9pfs_lock); + if (!priv || priv->client != client) + return -EINVAL; + + num = p9_req->tc->tag % priv->num_rings; + ring = &priv->rings[num]; + +again: + while (wait_event_interruptible(ring->wq, + p9_xen_write_todo(ring, size)) != 0) + ; + + spin_lock_irqsave(&ring->lock, flags); + cons = ring->intf->out_cons; + prod = ring->intf->out_prod; + virt_mb(); + + if (XEN_9PFS_RING_SIZE - xen_9pfs_queued(prod, cons, + XEN_9PFS_RING_SIZE) < size) { + spin_unlock_irqrestore(&ring->lock, flags); + goto again; + } + + masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE); + masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); + + xen_9pfs_write_packet(ring->data.out, p9_req->tc->sdata, size, + &masked_prod, masked_cons, XEN_9PFS_RING_SIZE); + + p9_req->status = REQ_STATUS_SENT; + virt_wmb(); /* write ring before updating pointer */ + prod += size; + ring->intf->out_prod = prod; + spin_unlock_irqrestore(&ring->lock, flags); + notify_remote_via_irq(ring->irq); + return 0; } -- 2.39.5