1 files changed, 21 insertions, 2 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index eeb8ac1aa856..f65ef8821c73 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1042,8 +1042,21 @@ grow_buffers(struct block_device *bdev, sector_t block, int size)
         } while ((size << sizebits) < PAGE_SIZE);
 
         index = block >> sizebits;
-        block = index << sizebits;
 
+        /*
+         * Check for a block which wants to lie outside our maximum possible
+         * pagecache index.  (this comparison is done using sector_t types).
+         */
+        if (unlikely(index != block >> sizebits)) {
+                char b[BDEVNAME_SIZE];
+
+                printk(KERN_ERR "%s: requested out-of-range block %llu for "
+                        "device %s\n",
+                        __FUNCTION__, (unsigned long long)block,
+                        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)
@@ -1070,12 +1083,16 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size)
 
         for (;;) {
                 struct buffer_head * bh;
+                int ret;
 
                 bh = __find_get_block(bdev, block, size);
                 if (bh)
                         return bh;
 
-                if (!grow_buffers(bdev, block, size))
+                ret = grow_buffers(bdev, block, size);
+                if (ret < 0)
+                        return NULL;
+                if (ret == 0)
                         free_more_memory();
         }
 }
@@ -1837,6 +1854,7 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
                         clear_buffer_new(bh);
                         kaddr = kmap_atomic(page, KM_USER0);
                         memset(kaddr+block_start, 0, bh->b_size);
+                        flush_dcache_page(page);
                         kunmap_atomic(kaddr, KM_USER0);
                         set_buffer_uptodate(bh);
                         mark_buffer_dirty(bh);
@@ -2343,6 +2361,7 @@ failed:
          */
         kaddr = kmap_atomic(page, KM_USER0);
         memset(kaddr, 0, PAGE_CACHE_SIZE);
+        flush_dcache_page(page);
         kunmap_atomic(kaddr, KM_USER0);
         SetPageUptodate(page);
         set_page_dirty(page);