1 files changed, 35 insertions, 33 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index d56d3c145b9f..ae4846ff4849 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -409,9 +409,9 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
 {
 	int error;
 
-	VM_BUG_ON_PAGE(!PageLocked(old), old);
-	VM_BUG_ON_PAGE(!PageLocked(new), new);
-	VM_BUG_ON_PAGE(new->mapping, new);
+	VM_BUG_ON(!PageLocked(old));
+	VM_BUG_ON(!PageLocked(new));
+	VM_BUG_ON(new->mapping);
 
 	error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
 	if (!error) {
@@ -461,8 +461,8 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 {
 	int error;
 
-	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(PageSwapBacked(page), page);
+	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON(PageSwapBacked(page));
 
 	error = mem_cgroup_cache_charge(page, current->mm,
 					gfp_mask & GFP_RECLAIM_MASK);
@@ -607,7 +607,7 @@ EXPORT_SYMBOL_GPL(add_page_wait_queue);
  */
 void unlock_page(struct page *page)
 {
-	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON(!PageLocked(page));
 	clear_bit_unlock(PG_locked, &page->flags);
 	smp_mb__after_clear_bit();
 	wake_up_page(page, PG_locked);
@@ -760,7 +760,7 @@ repeat:
 			page_cache_release(page);
 			goto repeat;
 		}
-		VM_BUG_ON_PAGE(page->index != offset, page);
+		VM_BUG_ON(page->index != offset);
 	}
 	return page;
 }
@@ -1090,6 +1090,7 @@ static void shrink_readahead_size_eio(struct file *filp,
  * @filp:	the file to read
  * @ppos:	current file position
  * @desc:	read_descriptor
+ * @actor:	read method
  *
  * This is a generic file read routine, and uses the
  * mapping->a_ops->readpage() function for the actual low-level stuff.
@@ -1098,7 +1099,7 @@ static void shrink_readahead_size_eio(struct file *filp,
  * of the logic when it comes to error handling etc.
  */
 static void do_generic_file_read(struct file *filp, loff_t *ppos,
-		read_descriptor_t *desc)
+		read_descriptor_t *desc, read_actor_t actor)
 {
 	struct address_space *mapping = filp->f_mapping;
 	struct inode *inode = mapping->host;
@@ -1199,14 +1200,13 @@ page_ok:
 		 * Ok, we have the page, and it's up-to-date, so
 		 * now we can copy it to user space...
 		 *
-		 * The file_read_actor routine returns how many bytes were
-		 * actually used..
+		 * The actor routine returns how many bytes were actually used..
 		 * NOTE! This may not be the same as how much of a user buffer
 		 * we filled up (we may be padding etc), so we can only update
 		 * "pos" here (the actor routine has to update the user buffer
 		 * pointers and the remaining count).
 		 */
-		ret = file_read_actor(desc, page, offset, nr);
+		ret = actor(desc, page, offset, nr);
 		offset += ret;
 		index += offset >> PAGE_CACHE_SHIFT;
 		offset &= ~PAGE_CACHE_MASK;
@@ -1428,28 +1428,30 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 		if (!count)
 			goto out; /* skip atime */
 		size = i_size_read(inode);
-		retval = filemap_write_and_wait_range(mapping, pos,
+		if (pos < size) {
+			retval = filemap_write_and_wait_range(mapping, pos,
 					pos + iov_length(iov, nr_segs) - 1);
-		if (!retval) {
-			retval = mapping->a_ops->direct_IO(READ, iocb,
-							   iov, pos, nr_segs);
-		}
-		if (retval > 0) {
-			*ppos = pos + retval;
-			count -= retval;
-		}
+			if (!retval) {
+				retval = mapping->a_ops->direct_IO(READ, iocb,
+							iov, pos, nr_segs);
+			}
+			if (retval > 0) {
+				*ppos = pos + retval;
+				count -= retval;
+			}
 
-		/*
-		 * Btrfs can have a short DIO read if we encounter
-		 * compressed extents, so if there was an error, or if
-		 * we've already read everything we wanted to, or if
-		 * there was a short read because we hit EOF, go ahead
-		 * and return.  Otherwise fallthrough to buffered io for
-		 * the rest of the read.
-		 */
-		if (retval < 0 || !count || *ppos >= size) {
-			file_accessed(filp);
-			goto out;
+			/*
+			 * Btrfs can have a short DIO read if we encounter
+			 * compressed extents, so if there was an error, or if
+			 * we've already read everything we wanted to, or if
+			 * there was a short read because we hit EOF, go ahead
+			 * and return.  Otherwise fallthrough to buffered io for
+			 * the rest of the read.
+			 */
+			if (retval < 0 || !count || *ppos >= size) {
+				file_accessed(filp);
+				goto out;
+			}
 		}
 	}
 
@@ -1477,7 +1479,7 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 		if (desc.count == 0)
 			continue;
 		desc.error = 0;
-		do_generic_file_read(filp, ppos, &desc);
+		do_generic_file_read(filp, ppos, &desc, file_read_actor);
 		retval += desc.written;
 		if (desc.error) {
 			retval = retval ?: desc.error;
@@ -1654,7 +1656,7 @@ retry_find:
 		put_page(page);
 		goto retry_find;
 	}
-	VM_BUG_ON_PAGE(page->index != offset, page);
+	VM_BUG_ON(page->index != offset);
 
 	/*
 	 * We have a locked page in the page cache, now we need to check