[RFC 11/11] ext4: add ext4_dax_pfn_mkwrite()

Ross Zwisler
2015-10-29T20:12:41Z

Add ext4_dax_pfn_mkwrite() that properly protects against freeze, sets
the file update time and calls into dax_pfn_mkwrite() to add the newly
dirtied page to the radix tree which tracks dirty DAX pages.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
fs/ext4/file.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 54d7729..7f62cad 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -272,11 +272,31 @@ static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
ext4_end_io_unwritten);
}

+static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ struct inode *inode = file_inode(vma->vm_file);
+ loff_t size;
+ int ret;
+
+ sb_start_pagefault(inode->i_sb);
+ file_update_time(vma->vm_file);
+
+ /* check that the faulting page hasn't raced with truncate */
+ size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (vmf->pgoff >= size)
+ ret = VM_FAULT_SIGBUS;
+ else
+ ret = dax_pfn_mkwrite(vma, vmf);
+
+ sb_end_pagefault(inode->i_sb);
+ return ret;
+}
+
static const struct vm_operations_struct ext4_dax_vm_ops = {
.fault = ext4_dax_fault,
.pmd_fault = ext4_dax_pmd_fault,
.page_mkwrite = ext4_dax_mkwrite,
- .pfn_mkwrite = dax_pfn_mkwrite,
+ .pfn_mkwrite = ext4_dax_pfn_mkwrite,
};
#else
#define ext4_dax_vm_ops ext4_file_vm_ops
--
2.1.0