Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull iov_iter updates from Al Viro:

 - bio_{map,copy}_user_iov() series; those are cleanups - fixes from the
   same pile went into mainline (and stable) in late September.

 - fs/iomap.c iov_iter-related fixes

 - new primitive - iov_iter_for_each_range(), which applies a function
   to kernel-mapped segments of an iov_iter.

   Usable for kvec and bvec ones, the latter does kmap()/kunmap() around
   the callback. _Not_ usable for iovec- or pipe-backed iov_iter; the
   latter is not hard to fix if the need ever appears, the former is by
   design.

   Another related primitive will have to wait for the next cycle - it
   passes page + offset + size instead of pointer + size, and that one
   will be usable for everything _except_ kvec. Unfortunately, that one
   didn't get exposure in -next yet, so...

 - a bit more lustre iov_iter work, including a use case for
   iov_iter_for_each_range() (checksum calculation)

 - vhost/scsi leak fix in failure exit

 - misc cleanups and detritectomy...

* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (21 commits)
  iomap_dio_actor(): fix iov_iter bugs
  switch ksocknal_lib_recv_...() to use of iov_iter_for_each_range()
  lustre: switch struct ksock_conn to iov_iter
  vhost/scsi: switch to iov_iter_get_pages()
  fix a page leak in vhost_scsi_iov_to_sgl() error recovery
  new primitive: iov_iter_for_each_range()
  lnet_return_rx_credits_locked: don't abuse list_entry
  xen: don't open-code iov_iter_kvec()
  orangefs: remove detritus from struct orangefs_kiocb_s
  kill iov_shorten()
  bio_alloc_map_data(): do bmd->iter setup right there
  bio_copy_user_iov(): saner bio size calculation
  bio_map_user_iov(): get rid of copying iov_iter
  bio_copy_from_iter(): get rid of copying iov_iter
  move more stuff down into bio_copy_user_iov()
  blk_rq_map_user_iov(): move iov_iter_advance() down
  bio_map_user_iov(): get rid of the iov_for_each()
  bio_map_user_iov(): move alignment check into the main loop
  don't rely upon subsequent bio_add_pc_page() calls failing
  ... and with iov_iter_get_pages_alloc() it becomes even simpler
  ...

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;
+	struct scatterlist *sg = sgl;
+	ssize_t bytes;
+	size_t offset;
+	unsigned int npages = 0;
 
-	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;
-	}
-
-	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
@@ -687,24 +664,20 @@ 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;
-	int i, ret;
+	struct scatterlist *p = sg;
+	int 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;
-
-		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) {
-			for (i = 0; i < sg_count; i++) {
-				struct page *page = sg_page(&sg[i]);
+			while (p < sg) {
+				struct page *page = sg_page(p++);
 				if (page)
 					put_page(page);
 			}
 			return ret;
 		}
 		sg += ret;
-		off = 0;
 	}
 	return 0;
 }