[PATCH 8/8] ext4: Transparent support for PUD-sized transparent huge pages

[Matthew Wilcox]

From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>

Call into DAX to provide support for PUD pages, just like the PMD cases.

Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
---
 fs/ext4/file.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 60683ab..b0cba51 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -262,6 +262,42 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
 	return result;
 }
 
+static int ext4_dax_pud_fault(struct vm_area_struct *vma, unsigned long addr,
+						pud_t *pud, unsigned int flags)
+{
+	int result;
+	handle_t *handle = NULL;
+	struct inode *inode = file_inode(vma->vm_file);
+	struct super_block *sb = inode->i_sb;
+	bool write = flags & FAULT_FLAG_WRITE;
+
+	if (write) {
+		sb_start_pagefault(sb);
+		file_update_time(vma->vm_file);
+		down_read(&EXT4_I(inode)->i_mmap_sem);
+		handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
+				ext4_chunk_trans_blocks(inode,
+							PMD_SIZE / PAGE_SIZE));
+	} else
+		down_read(&EXT4_I(inode)->i_mmap_sem);
+
+	if (IS_ERR(handle))
+		result = VM_FAULT_SIGBUS;
+	else
+		result = __dax_pud_fault(vma, addr, pud, flags,
+				ext4_dax_mmap_get_block, NULL);
+
+	if (write) {
+		if (!IS_ERR(handle))
+			ext4_journal_stop(handle);
+		up_read(&EXT4_I(inode)->i_mmap_sem);
+		sb_end_pagefault(sb);
+	} else
+		up_read(&EXT4_I(inode)->i_mmap_sem);
+
+	return result;
+}
+
 static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	int err;
@@ -309,6 +345,7 @@ static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
 static const struct vm_operations_struct ext4_dax_vm_ops = {
 	.fault		= ext4_dax_fault,
 	.pmd_fault	= ext4_dax_pmd_fault,
+	.pud_fault	= ext4_dax_pud_fault,
 	.page_mkwrite	= ext4_dax_mkwrite,
 	.pfn_mkwrite	= ext4_dax_pfn_mkwrite,
 };
-- 
2.6.2

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