mm: Pass info, not iter, into filemap_get_pages()

filemap_get_pages() and a number of functions that it calls take an
iterator to provide two things: the number of bytes to be got from the file
specified and whether partially uptodate pages are allowed.  Change these
functions so that this information is passed in directly.  This allows it
to be called without having an iterator to hand.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Christoph Hellwig <hch@lst.de>
cc: Matthew Wilcox <willy@infradead.org>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

mm/filemap.c

@@ -2440,21 +2440,19 @@ static int filemap_read_folio(struct file *file, filler_t filler,
 }
 
 static bool filemap_range_uptodate(struct address_space *mapping,
-		loff_t pos, struct iov_iter *iter, struct folio *folio)
+		loff_t pos, size_t count, struct folio *folio,
+		bool need_uptodate)
 {
-	int count;
-
 	if (folio_test_uptodate(folio))
 		return true;
 	/* pipes can't handle partially uptodate pages */
-	if (iov_iter_is_pipe(iter))
+	if (need_uptodate)
 		return false;
 	if (!mapping->a_ops->is_partially_uptodate)
 		return false;
 	if (mapping->host->i_blkbits >= folio_shift(folio))
 		return false;
 
-	count = iter->count;
 	if (folio_pos(folio) > pos) {
 		count -= folio_pos(folio) - pos;
 		pos = 0;
@@ -2466,8 +2464,8 @@ static bool filemap_range_uptodate(struct address_space *mapping,
 }
 
 static int filemap_update_page(struct kiocb *iocb,
-		struct address_space *mapping, struct iov_iter *iter,
-		struct folio *folio)
+		struct address_space *mapping, size_t count,
+		struct folio *folio, bool need_uptodate)
 {
 	int error;
 
@@ -2501,7 +2499,8 @@ static int filemap_update_page(struct kiocb *iocb,
 		goto unlock;
 
 	error = 0;
-	if (filemap_range_uptodate(mapping, iocb->ki_pos, iter, folio))
+	if (filemap_range_uptodate(mapping, iocb->ki_pos, count, folio,
+				   need_uptodate))
 		goto unlock;
 
 	error = -EAGAIN;
@@ -2577,8 +2576,8 @@ static int filemap_readahead(struct kiocb *iocb, struct file *file,
 	return 0;
 }
 
-static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
-		struct folio_batch *fbatch)
+static int filemap_get_pages(struct kiocb *iocb, size_t count,
+		struct folio_batch *fbatch, bool need_uptodate)
 {
 	struct file *filp = iocb->ki_filp;
 	struct address_space *mapping = filp->f_mapping;
@@ -2589,7 +2588,7 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
 	int err = 0;
 
 	/* "last_index" is the index of the page beyond the end of the read */
-	last_index = DIV_ROUND_UP(iocb->ki_pos + iter->count, PAGE_SIZE);
+	last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE);
 retry:
 	if (fatal_signal_pending(current))
 		return -EINTR;
@@ -2622,7 +2621,8 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
 		if ((iocb->ki_flags & IOCB_WAITQ) &&
 		    folio_batch_count(fbatch) > 1)
 			iocb->ki_flags |= IOCB_NOWAIT;
-		err = filemap_update_page(iocb, mapping, iter, folio);
+		err = filemap_update_page(iocb, mapping, count, folio,
+					  need_uptodate);
 		if (err)
 			goto err;
 	}
@@ -2692,7 +2692,8 @@ ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
 		if (unlikely(iocb->ki_pos >= i_size_read(inode)))
 			break;
 
-		error = filemap_get_pages(iocb, iter, &fbatch);
+		error = filemap_get_pages(iocb, iter->count, &fbatch,
+					  iov_iter_is_pipe(iter));
 		if (error < 0)
 			break;