Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/ext4/ext4.h  |    1 +
 fs/ext4/file.c  |   19 ++++++++++++++++++-
 fs/ext4/inode.c |   11 +++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff -puN fs/ext4/ext4.h~ext4-mm-ext4-page-mkwrite fs/ext4/ext4.h
--- a/fs/ext4/ext4.h~ext4-mm-ext4-page-mkwrite
+++ a/fs/ext4/ext4.h
@@ -1049,6 +1049,7 @@ extern void ext4_set_aops(struct inode *
 extern int ext4_writepage_trans_blocks(struct inode *);
 extern int ext4_block_truncate_page(handle_t *handle, struct page *page,
 		struct address_space *mapping, loff_t from);
+extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page);
 
 /* ioctl.c */
 extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
diff -puN fs/ext4/file.c~ext4-mm-ext4-page-mkwrite fs/ext4/file.c
--- a/fs/ext4/file.c~ext4-mm-ext4-page-mkwrite
+++ a/fs/ext4/file.c
@@ -123,6 +123,23 @@ force_commit:
 	return ret;
 }
 
+static struct vm_operations_struct ext4_file_vm_ops = {
+	.fault		= filemap_fault,
+	.page_mkwrite   = ext4_page_mkwrite,
+};
+
+static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct address_space *mapping = file->f_mapping;
+
+	if (!mapping->a_ops->readpage)
+		return -ENOEXEC;
+	file_accessed(file);
+	vma->vm_ops = &ext4_file_vm_ops;
+	vma->vm_flags |= VM_CAN_NONLINEAR;
+	return 0;
+}
+
 const struct file_operations ext4_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= do_sync_read,
@@ -133,7 +150,7 @@ const struct file_operations ext4_file_o
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext4_compat_ioctl,
 #endif
-	.mmap		= generic_file_mmap,
+	.mmap		= ext4_file_mmap,
 	.open		= generic_file_open,
 	.release	= ext4_release_file,
 	.fsync		= ext4_sync_file,
diff -puN fs/ext4/inode.c~ext4-mm-ext4-page-mkwrite fs/ext4/inode.c
--- a/fs/ext4/inode.c~ext4-mm-ext4-page-mkwrite
+++ a/fs/ext4/inode.c
@@ -3510,3 +3510,14 @@ int ext4_change_inode_journal_flag(struc
 
 	return err;
 }
+
+int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+{
+	/*
+	 * if ext4_get_block resulted in a split of an uninitialized extent,
+	 * in file system full case, we will have to take the journal write
+	 * access and zero out the page. The journal handle get initialized
+	 * in ext4_get_block.
+	 */
+	return block_page_mkwrite(vma, page, ext4_get_block);
+}
_