udf: Fix races with i_size changes during readpage

[sfrench/cifs-2.6.git] / fs / udf / file.c

diff --git a/fs/udf/file.c b/fs/udf/file.c
index f5eb2d5b3bac86d91eaaddddbec6237dbbadfa38..e06d2c15749a50027757eef97c667e2352e29714 100644 (file)
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -43,10 +43,15 @@ static void __udf_adinicb_readpage(struct page *page)
        struct inode *inode = page->mapping->host;
        char *kaddr;
        struct udf_inode_info *iinfo = UDF_I(inode);
+       loff_t isize = i_size_read(inode);
 
+       /*
+        * We have to be careful here as truncate can change i_size under us.
+        * So just sample it once and use the same value everywhere.
+        */
        kaddr = kmap_atomic(page);
-       memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, inode->i_size);
-       memset(kaddr + inode->i_size, 0, PAGE_SIZE - inode->i_size);
+       memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, isize);
+       memset(kaddr + isize, 0, PAGE_SIZE - isize);
        flush_dcache_page(page);
        SetPageUptodate(page);
        kunmap_atomic(kaddr);