| Message ID | f31e80bc67774d08f8d3bfb7ca0a970eeb369ca5.1632156835.git.linux_oss@crudebyte.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net/9p: remove msize limit in virtio transport | expand |
On Montag, 20. September 2021 18:44:13 CEST Christian Schoenebeck wrote: > 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 | 57 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 57 insertions(+) > > diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c > index 0db8de84bd51..4cb75f45aa15 100644 > --- a/net/9p/trans_virtio.c > +++ b/net/9p/trans_virtio.c > @@ -200,6 +200,31 @@ 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 > @@ -771,6 +796,10 @@ 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; > @@ -793,6 +822,34 @@ 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; > + 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); > + } > + } Maybe an ... } else { pr_info(...); } would be useful here to explain the user why transport refrained from increasing its max size even though user's msize option demanded it. > +#endif /* CONFIG_ARCH_NO_SG_CHAIN */ > + } > + > client->trans = (void *)chan; > client->status = Connected; > chan->client = client;
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 0db8de84bd51..4cb75f45aa15 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -200,6 +200,31 @@ 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 @@ -771,6 +796,10 @@ 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; @@ -793,6 +822,34 @@ 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; + 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 | 57 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+)