[PATCHv2 31/41] ext4: handle huge pages in ext4_page_mkwrite()

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

Trivial: remove assumption on page size.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 fs/ext4/inode.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f585f9160a96..cd435d4a10f0 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5646,7 +5646,7 @@ static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
 
 int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
-	struct page *page = vmf->page;
+	struct page *page = compound_head(vmf->page);
 	loff_t size;
 	unsigned long len;
 	int ret;
@@ -5682,10 +5682,10 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 		goto out;
 	}
 
-	if (page->index == size >> PAGE_SHIFT)
-		len = size & ~PAGE_MASK;
-	else
-		len = PAGE_SIZE;
+	len = hpage_size(page);
+	if (page->index + hpage_nr_pages(page) - 1 == size >> PAGE_SHIFT)
+		len = size & ~hpage_mask(page);
+
 	/*
 	 * Return if we have all the buffers mapped. This avoids the need to do
 	 * journal_start/journal_stop which can block and take a long time
@@ -5716,7 +5716,8 @@ retry_alloc:
 	ret = block_page_mkwrite(vma, vmf, get_block);
 	if (!ret && ext4_should_journal_data(inode)) {
 		if (ext4_walk_page_buffers(handle, page_buffers(page), 0,
-			  PAGE_SIZE, NULL, do_journal_get_write_access)) {
+			  hpage_size(page), NULL,
+			  do_journal_get_write_access)) {
 			unlock_page(page);
 			ret = VM_FAULT_SIGBUS;
 			ext4_journal_stop(handle);
-- 
2.8.1