1 files changed, 25 insertions, 25 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index c780e39..bfed1ba 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -962,13 +962,14 @@ link_dev_buffers(struct page *page, struct buffer_head *head)
 /*
  * Initialise the state of a blockdev page's buffers.
  */ 
-static void
+static sector_t
 init_page_buffers(struct page *page, struct block_device *bdev,
 			sector_t block, int size)
 {
 	struct buffer_head *head = page_buffers(page);
 	struct buffer_head *bh = head;
 	int uptodate = PageUptodate(page);
+	sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode));
 
 	do {
 		if (!buffer_mapped(bh)) {
@@ -977,25 +978,33 @@ init_page_buffers(struct page *page, struct block_device *bdev,
 			bh->b_blocknr = block;
 			if (uptodate)
 				set_buffer_uptodate(bh);
-			set_buffer_mapped(bh);
+			if (block < end_block)
+				set_buffer_mapped(bh);
 		}
 		block++;
 		bh = bh->b_this_page;
 	} while (bh != head);
+
+	/*
+	 * Caller needs to validate requested block against end of device.
+	 */
+	return end_block;
 }
 
 /*
  * Create the page-cache page that contains the requested block.
  *
- * This is user purely for blockdev mappings.
+ * This is used purely for blockdev mappings.
  */
-static struct page *
+static int
 grow_dev_page(struct block_device *bdev, sector_t block,
-		pgoff_t index, int size)
+		pgoff_t index, int size, int sizebits)
 {
 	struct inode *inode = bdev->bd_inode;
 	struct page *page;
 	struct buffer_head *bh;
+	sector_t end_block;
+	int ret = 0;		/* Will call free_more_memory() */
 
 #ifdef CONFIG_DMA_CMA
 	page = find_or_create_page(inode->i_mapping, index,
@@ -1005,15 +1014,16 @@ grow_dev_page(struct block_device *bdev, sector_t block,
 		(mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
 #endif
 	if (!page)
-		return NULL;
+		return ret;
 
 	BUG_ON(!PageLocked(page));
 
 	if (page_has_buffers(page)) {
 		bh = page_buffers(page);
 		if (bh->b_size == size) {
-			init_page_buffers(page, bdev, block, size);
-			return page;
+			end_block = init_page_buffers(page, bdev,
+						index << sizebits, size);
+			goto done;
 		}
 		if (!try_to_free_buffers(page))
 			goto failed;
@@ -1033,15 +1043,15 @@ grow_dev_page(struct block_device *bdev, sector_t block,
 	 */
 	spin_lock(&inode->i_mapping->private_lock);
 	link_dev_buffers(page, bh);
-	init_page_buffers(page, bdev, block, size);
+	end_block = init_page_buffers(page, bdev, index << sizebits, size);
 	spin_unlock(&inode->i_mapping->private_lock);
-	return page;
+done:
+	ret = (block < end_block) ? 1 : -ENXIO;
 
 failed:
-	BUG();
 	unlock_page(page);
 	page_cache_release(page);
-	return NULL;
+	return ret;
 }
 
 /*
@@ -1051,7 +1061,6 @@ failed:
 static int
 grow_buffers(struct block_device *bdev, sector_t block, int size)
 {
-	struct page *page;
 	pgoff_t index;
 	int sizebits;
 
@@ -1075,14 +1084,9 @@ grow_buffers(struct block_device *bdev, sector_t block, int size)
 			bdevname(bdev, b));
 		return -EIO;
 	}
-	block = index << sizebits;
+
 	/* Create a page with the proper size buffers.. */
-	page = grow_dev_page(bdev, block, index, size);
-	if (!page)
-		return 0;
-	unlock_page(page);
-	page_cache_release(page);
-	return 1;
+	return grow_dev_page(bdev, block, index, size, sizebits);
 }
 
 static struct buffer_head *
@@ -1101,7 +1105,7 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size)
 	}
 
 	for (;;) {
-		struct buffer_head * bh;
+		struct buffer_head *bh;
 		int ret;
 
 		bh = __find_get_block(bdev, block, size);
@@ -1379,10 +1383,6 @@ EXPORT_SYMBOL(__find_get_block);
  * which corresponds to the passed block_device, block and size. The
  * returned buffer has its reference count incremented.
  *
- * __getblk() cannot fail - it just keeps trying.  If you pass it an
- * illegal block number, __getblk() will happily return a buffer_head
- * which represents the non-existent block.  Very weird.
- *
  * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
  * attempt is failing.  FIXME, perhaps?
  */