virtiofs: define dax address space operations

This is done along the lines of ext4 and xfs.  I primarily wanted
->writepages hook at this time so that I could call into
dax_writeback_mapping_range().  This in turn will decide which pfns need to
be written back.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index b8ec7d6..c213054 100644 (file)
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -575,6 +575,16 @@ out:
        return ret;
 }
 
+static int fuse_dax_writepages(struct address_space *mapping,
+                              struct writeback_control *wbc)
+{
+
+       struct inode *inode = mapping->host;
+       struct fuse_conn *fc = get_fuse_conn(inode);
+
+       return dax_writeback_mapping_range(mapping, fc->dax->dev, wbc);
+}
+
 static vm_fault_t __fuse_dax_fault(struct vm_fault *vmf,
                                   enum page_entry_size pe_size, bool write)
 {
@@ -741,6 +751,13 @@ bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi)
        return true;
 }
 
+static const struct address_space_operations fuse_dax_file_aops  = {
+       .writepages     = fuse_dax_writepages,
+       .direct_IO      = noop_direct_IO,
+       .set_page_dirty = noop_set_page_dirty,
+       .invalidatepage = noop_invalidatepage,
+};
+
 void fuse_dax_inode_init(struct inode *inode)
 {
        struct fuse_conn *fc = get_fuse_conn(inode);
@@ -749,6 +766,7 @@ void fuse_dax_inode_init(struct inode *inode)
                return;
 
        inode->i_flags |= S_DAX;
+       inode->i_data.a_ops = &fuse_dax_file_aops;
 }
 
 bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment)