From 4f3b35c157e43107cc7e1f1aa06694e8b22e10bb Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 1 Apr 2015 19:57:53 -0400 Subject: 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 --- net/9p/trans_virtio.c | 137 +++++++++++++++++++++++++++++--------------------- 1 file changed, 79 insertions(+), 58 deletions(-) (limited to 'net/9p/trans_virtio.c') 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 @@ static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) * @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 @@ pack_sg_list_p(struct scatterlist *sg, int start, int limit, * 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 @@ req_retry: } 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 @@ static int p9_get_mapped_pages(struct virtio_chan *chan, 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); + 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); + } + 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(data); - data += s; - nr_pages--; + (*pages)[index] = kmap_to_page(p); + p += PAGE_SIZE; } - nr_pages = count; + return len; } - return nr_pages; } /** @@ -364,8 +394,8 @@ static int p9_get_mapped_pages(struct virtio_chan *chan, */ 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 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, 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; - } - 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; + 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; } - } - 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 @@ req_retry_pinned: 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 @@ req_retry_pinned: 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 @@ req_retry_pinned: * 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); -- cgit v1.1