bio_map_user_iov(): switch to iov_iter_get_pages()/iov_iter_advance()

... and to hell with iov_for_each() nonsense

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

diff --git a/block/bio.c b/block/bio.c
index 101c2a9..5de54de 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1328,7 +1328,7 @@ struct bio *bio_map_user_iov(struct request_queue *q,
        struct page **pages;
        struct bio *bio;
        int cur_page = 0;
-       int ret, offset;
+       int ret;
        struct iov_iter i;
        struct iovec iov;
        struct bio_vec *bvec;
@@ -1365,43 +1365,32 @@ struct bio *bio_map_user_iov(struct request_queue *q,
        if (!pages)
                goto out;
 
-       iov_for_each(iov, i, *iter) {
-               unsigned long uaddr = (unsigned long) iov.iov_base;
-               unsigned long len = iov.iov_len;
-               unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
-               unsigned long start = uaddr >> PAGE_SHIFT;
-               const int local_nr_pages = end - start;
-               const int page_limit = cur_page + local_nr_pages;
-
-               ret = get_user_pages_fast(uaddr, local_nr_pages,
-                               (iter->type & WRITE) != WRITE,
-                               &pages[cur_page]);
-               if (unlikely(ret < local_nr_pages)) {
-                       for (j = cur_page; j < page_limit; j++) {
-                               if (!pages[j])
-                                       break;
-                               put_page(pages[j]);
-                       }
-                       ret = -EFAULT;
+       i = *iter;
+       while (iov_iter_count(&i)) {
+               ssize_t bytes;
+               size_t offs, added = 0;
+               int npages;
+
+               bytes = iov_iter_get_pages(&i, pages + cur_page, LONG_MAX,
+                                               nr_pages - cur_page, &offs);
+               if (unlikely(bytes <= 0)) {
+                       ret = bytes ? bytes : -EFAULT;
                        goto out_unmap;
                }
 
-               offset = offset_in_page(uaddr);
-               for (j = cur_page; j < page_limit; j++) {
-                       unsigned int bytes = PAGE_SIZE - offset;
+               npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
+
+               for (j = cur_page; j < cur_page + npages; j++) {
+                       unsigned int n = PAGE_SIZE - offs;
                        unsigned short prev_bi_vcnt = bio->bi_vcnt;
 
-                       if (len <= 0)
-                               break;
-                       
-                       if (bytes > len)
-                               bytes = len;
+                       if (n > bytes)
+                               n = bytes;
 
                        /*
                         * sorry...
                         */
-                       if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
-                                           bytes)
+                       if (bio_add_pc_page(q, bio, pages[j], n, offs) < n)
                                break;
 
                        /*
@@ -1411,16 +1400,18 @@ struct bio *bio_map_user_iov(struct request_queue *q,
                        if (bio->bi_vcnt == prev_bi_vcnt)
                                put_page(pages[j]);
 
-                       len -= bytes;
-                       offset = 0;
+                       added += n;
+                       bytes -= n;
+                       offs = 0;
                }
+               iov_iter_advance(&i, added);
 
-               cur_page = j;
                /*
                 * release the pages we didn't map into the bio, if any
                 */
-               while (j < page_limit)
+               while (j < cur_page + npages)
                        put_page(pages[j++]);
+               cur_page = j;
        }
 
        kfree(pages);