1 files changed, 29 insertions, 6 deletions

diff --git a/fs/udf/file.c b/fs/udf/file.c
index 7f3f7ba3df6e..d1c6093fd3d3 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -39,20 +39,24 @@
 #include "udf_i.h"
 #include "udf_sb.h"
 
-static int udf_adinicb_readpage(struct file *file, struct page *page)
+static void __udf_adinicb_readpage(struct page *page)
 {
         struct inode *inode = page->mapping->host;
         char *kaddr;
         struct udf_inode_info *iinfo = UDF_I(inode);
 
-        BUG_ON(!PageLocked(page));
-
         kaddr = kmap(page);
-        memset(kaddr, 0, PAGE_CACHE_SIZE);
         memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, inode->i_size);
+        memset(kaddr + inode->i_size, 0, PAGE_CACHE_SIZE - inode->i_size);
         flush_dcache_page(page);
         SetPageUptodate(page);
         kunmap(page);
+}
+
+static int udf_adinicb_readpage(struct file *file, struct page *page)
+{
+        BUG_ON(!PageLocked(page));
+        __udf_adinicb_readpage(page);
         unlock_page(page);
 
         return 0;
@@ -77,6 +81,25 @@ static int udf_adinicb_writepage(struct page *page,
         return 0;
 }
 
+static int udf_adinicb_write_begin(struct file *file,
+                        struct address_space *mapping, loff_t pos,
+                        unsigned len, unsigned flags, struct page **pagep,
+                        void **fsdata)
+{
+        struct page *page;
+
+        if (WARN_ON_ONCE(pos >= PAGE_CACHE_SIZE))
+                return -EIO;
+        page = grab_cache_page_write_begin(mapping, 0, flags);
+        if (!page)
+                return -ENOMEM;
+        *pagep = page;
+
+        if (!PageUptodate(page) && len != PAGE_CACHE_SIZE)
+                __udf_adinicb_readpage(page);
+        return 0;
+}
+
 static int udf_adinicb_write_end(struct file *file,
                         struct address_space *mapping,
                         loff_t pos, unsigned len, unsigned copied,
@@ -98,8 +121,8 @@ static int udf_adinicb_write_end(struct file *file,
 const struct address_space_operations udf_adinicb_aops = {
         .readpage       = udf_adinicb_readpage,
         .writepage      = udf_adinicb_writepage,
-        .write_begin = simple_write_begin,
-        .write_end = udf_adinicb_write_end,
+        .write_begin    = udf_adinicb_write_begin,
+        .write_end      = udf_adinicb_write_end,
 };
 
 static ssize_t udf_file_aio_write(struct kiocb *iocb, const struct iovec *iov,