net/9p: switch the guts of p9_client_{read,write}() to iov_iter
... and have get_user_pages_fast() mapping fewer pages than requested
to generate a short read/write.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 36a1a73..e62bcbb 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -217,15 +217,15 @@
* @start: which segment of the sg_list to start at
* @pdata: a list of pages to add into sg.
* @nr_pages: number of pages to pack into the scatter/gather list
- * @data: data to pack into scatter/gather list
+ * @offs: amount of data in the beginning of first page _not_ to pack
* @count: amount of data to pack into the scatter/gather list
*/
static int
pack_sg_list_p(struct scatterlist *sg, int start, int limit,
- struct page **pdata, int nr_pages, char *data, int count)
+ struct page **pdata, int nr_pages, size_t offs, int count)
{
int i = 0, s;
- int data_off;
+ int data_off = offs;
int index = start;
BUG_ON(nr_pages > (limit - start));
@@ -233,16 +233,14 @@
* if the first page doesn't start at
* page boundary find the offset
*/
- data_off = offset_in_page(data);
while (nr_pages) {
- s = rest_of_page(data);
+ s = PAGE_SIZE - data_off;
if (s > count)
s = count;
/* Make sure we don't terminate early. */
sg_unmark_end(&sg[index]);
sg_set_page(&sg[index++], pdata[i++], s, data_off);
data_off = 0;
- data += s;
count -= s;
nr_pages--;
}
@@ -314,11 +312,20 @@
}
static int p9_get_mapped_pages(struct virtio_chan *chan,
- struct page **pages, char *data,
- int nr_pages, int write, int kern_buf)
+ struct page ***pages,
+ struct iov_iter *data,
+ int count,
+ size_t *offs,
+ int *need_drop)
{
+ int nr_pages;
int err;
- if (!kern_buf) {
+
+ if (!iov_iter_count(data))
+ return 0;
+
+ if (!(data->type & ITER_KVEC)) {
+ int n;
/*
* We allow only p9_max_pages pinned. We wait for the
* Other zc request to finish here
@@ -329,26 +336,49 @@
if (err == -ERESTARTSYS)
return err;
}
- err = p9_payload_gup(data, &nr_pages, pages, write);
- if (err < 0)
- return err;
+ n = iov_iter_get_pages_alloc(data, pages, count, offs);
+ if (n < 0)
+ return n;
+ *need_drop = 1;
+ nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE);
atomic_add(nr_pages, &vp_pinned);
+ return n;
} else {
/* kernel buffer, no need to pin pages */
- int s, index = 0;
- int count = nr_pages;
- while (nr_pages) {
- s = rest_of_page(data);
- if (is_vmalloc_addr(data))
- pages[index++] = vmalloc_to_page(data);
- else
- pages[index++] = kmap_to_page(data);
- data += s;
- nr_pages--;
+ int index;
+ size_t len;
+ void *p;
+
+ /* we'd already checked that it's non-empty */
+ while (1) {
+ len = iov_iter_single_seg_count(data);
+ if (likely(len)) {
+ p = data->kvec->iov_base + data->iov_offset;
+ break;
+ }
+ iov_iter_advance(data, 0);
}
- nr_pages = count;
+ if (len > count)
+ len = count;
+
+ nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) -
+ (unsigned long)p / PAGE_SIZE;
+
+ *pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
+ if (!*pages)
+ return -ENOMEM;
+
+ *need_drop = 0;
+ p -= (*offs = (unsigned long)p % PAGE_SIZE);
+ for (index = 0; index < nr_pages; index++) {
+ if (is_vmalloc_addr(p))
+ (*pages)[index] = vmalloc_to_page(p);
+ else
+ (*pages)[index] = kmap_to_page(p);
+ p += PAGE_SIZE;
+ }
+ return len;
}
- return nr_pages;
}
/**
@@ -364,8 +394,8 @@
*/
static int
p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
- char *uidata, char *uodata, int inlen,
- int outlen, int in_hdr_len, int kern_buf)
+ struct iov_iter *uidata, struct iov_iter *uodata,
+ int inlen, int outlen, int in_hdr_len)
{
int in, out, err, out_sgs, in_sgs;
unsigned long flags;
@@ -373,41 +403,32 @@
struct page **in_pages = NULL, **out_pages = NULL;
struct virtio_chan *chan = client->trans;
struct scatterlist *sgs[4];
+ size_t offs;
+ int need_drop = 0;
p9_debug(P9_DEBUG_TRANS, "virtio request\n");
if (uodata) {
- out_nr_pages = p9_nr_pages(uodata, outlen);
- out_pages = kmalloc(sizeof(struct page *) * out_nr_pages,
- GFP_NOFS);
- if (!out_pages) {
- err = -ENOMEM;
- goto err_out;
+ int n = p9_get_mapped_pages(chan, &out_pages, uodata,
+ outlen, &offs, &need_drop);
+ if (n < 0)
+ return n;
+ out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
+ if (n != outlen) {
+ __le32 v = cpu_to_le32(n);
+ memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
+ outlen = n;
}
- out_nr_pages = p9_get_mapped_pages(chan, out_pages, uodata,
- out_nr_pages, 0, kern_buf);
- if (out_nr_pages < 0) {
- err = out_nr_pages;
- kfree(out_pages);
- out_pages = NULL;
- goto err_out;
- }
- }
- if (uidata) {
- in_nr_pages = p9_nr_pages(uidata, inlen);
- in_pages = kmalloc(sizeof(struct page *) * in_nr_pages,
- GFP_NOFS);
- if (!in_pages) {
- err = -ENOMEM;
- goto err_out;
- }
- in_nr_pages = p9_get_mapped_pages(chan, in_pages, uidata,
- in_nr_pages, 1, kern_buf);
- if (in_nr_pages < 0) {
- err = in_nr_pages;
- kfree(in_pages);
- in_pages = NULL;
- goto err_out;
+ } else if (uidata) {
+ int n = p9_get_mapped_pages(chan, &in_pages, uidata,
+ inlen, &offs, &need_drop);
+ if (n < 0)
+ return n;
+ in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
+ if (n != inlen) {
+ __le32 v = cpu_to_le32(n);
+ memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
+ inlen = n;
}
}
req->status = REQ_STATUS_SENT;
@@ -426,7 +447,7 @@
if (out_pages) {
sgs[out_sgs++] = chan->sg + out;
out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
- out_pages, out_nr_pages, uodata, outlen);
+ out_pages, out_nr_pages, offs, outlen);
}
/*
@@ -444,7 +465,7 @@
if (in_pages) {
sgs[out_sgs + in_sgs++] = chan->sg + out + in;
in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
- in_pages, in_nr_pages, uidata, inlen);
+ in_pages, in_nr_pages, offs, inlen);
}
BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));
@@ -478,7 +499,7 @@
* Non kernel buffers are pinned, unpin them
*/
err_out:
- if (!kern_buf) {
+ if (need_drop) {
if (in_pages) {
p9_release_pages(in_pages, in_nr_pages);
atomic_sub(in_nr_pages, &vp_pinned);