[PATCH 01/19] mm: Make default vm_ops provide ->page_mkwrite handler

[Jan Kara <jack@suse.cz>]

Make default vm_ops provide ->page_mkwrite handler. Currently it only updates
file's modification times and gets locked page but later it will also handle
filesystem freezing.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 include/linux/mm.h |    1 +
 mm/filemap.c       |   20 ++++++++++++++++++++
 mm/filemap_xip.c   |    1 +
 3 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 17b27cd..074c075 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1419,6 +1419,7 @@ extern void truncate_inode_pages_range(struct address_space *,
 
 /* generic vm_area_ops exported for stackable file systems */
 extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
+extern int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
 
 /* mm/page-writeback.c */
 int write_one_page(struct page *page, int wait);
diff --git a/mm/filemap.c b/mm/filemap.c
index b662757..b865c0b 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1759,8 +1759,28 @@ page_not_uptodate:
 }
 EXPORT_SYMBOL(filemap_fault);
 
+int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+	int ret = VM_FAULT_LOCKED;
+
+	file_update_time(vma->vm_file);
+	lock_page(page);
+	if ((page->mapping != inode->i_mapping) ||
+	    (page_offset(page) > i_size_read(inode))) {
+		unlock_page(page);
+		ret = VM_FAULT_NOPAGE;
+		goto out;
+	}
+out:
+	return ret;
+}
+EXPORT_SYMBOL(filemap_page_mkwrite);
+
 const struct vm_operations_struct generic_file_vm_ops = {
 	.fault		= filemap_fault,
+	.page_mkwrite	= filemap_page_mkwrite,
 };
 
 /* This is used for a general mmap of a disk file */
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index a4eb311..591dba6 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -304,6 +304,7 @@ out:
 
 static const struct vm_operations_struct xip_file_vm_ops = {
 	.fault	= xip_file_fault,
+	.page_mkwrite	= filemap_page_mkwrite,
 };
 
 int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
-- 
1.7.1