@@ -203,6 +203,31 @@ static struct virtqueue_sg *vq_sg_alloc(unsigned int nsgl)
return vq_sg;
}
+/**
+ * vq_sg_resize - resize passed virtqueue scatter/gather lists to the passed
+ * amount of lists
+ * @_vq_sg: scatter/gather lists to be resized
+ * @nsgl: new amount of scatter/gather lists
+ */
+static int vq_sg_resize(struct virtqueue_sg **_vq_sg, unsigned int nsgl)
+{
+ struct virtqueue_sg *vq_sg;
+
+ BUG_ON(!_vq_sg || !nsgl);
+ vq_sg = *_vq_sg;
+ if (vq_sg->nsgl == nsgl)
+ return 0;
+
+ /* lazy resize implementation for now */
+ vq_sg = vq_sg_alloc(nsgl);
+ if (!vq_sg)
+ return -ENOMEM;
+
+ kfree(*_vq_sg);
+ *_vq_sg = vq_sg;
+ return 0;
+}
+
/**
* p9_virtio_close - reclaim resources of a channel
* @client: client instance
@@ -774,6 +799,10 @@ p9_virtio_create(struct p9_client *client, const char *devname, char *args)
struct virtio_chan *chan;
int ret = -ENOENT;
int found = 0;
+#if !defined(CONFIG_ARCH_NO_SG_CHAIN)
+ size_t npages;
+ size_t nsgl;
+#endif
if (devname == NULL)
return -EINVAL;
@@ -796,6 +825,38 @@ p9_virtio_create(struct p9_client *client, const char *devname, char *args)
return ret;
}
+ /*
+ * if user supplied an 'msize' option that's larger than what this
+ * transport supports by default, then try to allocate more sg lists
+ */
+ if (client->msize > client->trans_maxsize) {
+#ifdef CONFIG_ARCH_NO_SG_CHAIN
+ pr_info("limiting 'msize' to %d because architecture does not "
+ "support chained scatter gather lists\n",
+ client->trans_maxsize);
+#else
+ npages = DIV_ROUND_UP(client->msize, PAGE_SIZE);
+ if (npages > chan->p9_max_pages) {
+ npages = chan->p9_max_pages;
+ pr_info("limiting 'msize' as it would exceed the max. "
+ "of %lu pages allowed on this system\n",
+ chan->p9_max_pages);
+ }
+ nsgl = DIV_ROUND_UP(npages, SG_USER_PAGES_PER_LIST);
+ if (nsgl > chan->vq_sg->nsgl) {
+ /*
+ * if resize fails, no big deal, then just
+ * continue with default msize instead
+ */
+ if (!vq_sg_resize(&chan->vq_sg, nsgl)) {
+ client->trans_maxsize =
+ PAGE_SIZE *
+ ((nsgl * SG_USER_PAGES_PER_LIST) - 3);
+ }
+ }
+#endif /* CONFIG_ARCH_NO_SG_CHAIN */
+ }
+
client->trans = (void *)chan;
client->status = Connected;
chan->client = client;
The virtio transport supports by default a 9p 'msize' of up to approximately 500 kB. This patch adds support for larger 'msize' values by resizing the amount of scatter/gather lists if required. Signed-off-by: Christian Schoenebeck <linux_oss@crudebyte.com> --- net/9p/trans_virtio.c | 61 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+)