vhost/scsi: switch to iov_iter_get_pages()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 20 insertions, 48 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index e47c5bc3ddca..e5b18320f1a3 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -210,12 +210,6 @@ static struct workqueue_struct *vhost_scsi_workqueue;
 static DEFINE_MUTEX(vhost_scsi_mutex);
 static LIST_HEAD(vhost_scsi_list);
 
-static int iov_num_pages(void __user *iov_base, size_t iov_len)
-{
-        return (PAGE_ALIGN((unsigned long)iov_base + iov_len) -
-               ((unsigned long)iov_base & PAGE_MASK)) >> PAGE_SHIFT;
-}
-
 static void vhost_scsi_done_inflight(struct kref *kref)
 {
         struct vhost_scsi_inflight *inflight;
@@ -618,48 +612,31 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
  */
 static int
 vhost_scsi_map_to_sgl(struct vhost_scsi_cmd *cmd,
-                      void __user *ptr,
-                      size_t len,
+                      struct iov_iter *iter,
                       struct scatterlist *sgl,
                       bool write)
 {
-        unsigned int npages = 0, offset, nbytes;
-        unsigned int pages_nr = iov_num_pages(ptr, len);
-        struct scatterlist *sg = sgl;
         struct page **pages = cmd->tvc_upages;
-        int ret, i;
-
-        if (pages_nr > VHOST_SCSI_PREALLOC_UPAGES) {
-                pr_err("vhost_scsi_map_to_sgl() pages_nr: %u greater than"
-                       " preallocated VHOST_SCSI_PREALLOC_UPAGES: %u\n",
-                        pages_nr, VHOST_SCSI_PREALLOC_UPAGES);
-                return -ENOBUFS;
-        }
+        struct scatterlist *sg = sgl;
+        ssize_t bytes;
+        size_t offset;
+        unsigned int npages = 0;
 
-        ret = get_user_pages_fast((unsigned long)ptr, pages_nr, write, pages);
+        bytes = iov_iter_get_pages(iter, pages, LONG_MAX,
+                                VHOST_SCSI_PREALLOC_UPAGES, &offset);
         /* No pages were pinned */
-        if (ret < 0)
-                goto out;
-        /* Less pages pinned than wanted */
-        if (ret != pages_nr) {
-                for (i = 0; i < ret; i++)
-                        put_page(pages[i]);
-                ret = -EFAULT;
-                goto out;
-        }
+        if (bytes <= 0)
+                return bytes < 0 ? bytes : -EFAULT;
 
-        while (len > 0) {
-                offset = (uintptr_t)ptr & ~PAGE_MASK;
-                nbytes = min_t(unsigned int, PAGE_SIZE - offset, len);
-                sg_set_page(sg, pages[npages], nbytes, offset);
-                ptr += nbytes;
-                len -= nbytes;
-                sg++;
-                npages++;
-        }
+        iov_iter_advance(iter, bytes);
 
-out:
-        return ret;
+        while (bytes) {
+                unsigned n = min_t(unsigned, PAGE_SIZE - offset, bytes);
+                sg_set_page(sg++, pages[npages++], n, offset);
+                bytes -= n;
+                offset = 0;
+        }
+        return npages;
 }
 
 static int
@@ -687,15 +664,11 @@ vhost_scsi_iov_to_sgl(struct vhost_scsi_cmd *cmd, bool write,
                       struct iov_iter *iter,
                       struct scatterlist *sg, int sg_count)
 {
-        size_t off = iter->iov_offset;
         struct scatterlist *p = sg;
-        int i, ret;
-
-        for (i = 0; i < iter->nr_segs; i++) {
-                void __user *base = iter->iov[i].iov_base + off;
-                size_t len = iter->iov[i].iov_len - off;
+        int ret;
 
-                ret = vhost_scsi_map_to_sgl(cmd, base, len, sg, write);
+        while (iov_iter_count(iter)) {
+                ret = vhost_scsi_map_to_sgl(cmd, iter, sg, write);
                 if (ret < 0) {
                         while (p < sg) {
                                 struct page *page = sg_page(p++);
@@ -705,7 +678,6 @@ vhost_scsi_iov_to_sgl(struct vhost_scsi_cmd *cmd, bool write,
                         return ret;
                 }
                 sg += ret;
-                off = 0;
         }
         return 0;
 }