[PATCH v5 03/11] ext4, dax: introduce ext4_dax_aops

[Dan Williams]

In preparation for the dax implementation to start associating dax pages
to inodes via page->mapping, we need to provide a 'struct
address_space_operations' instance for dax. Otherwise, direct-I/O
triggers incorrect page cache assumptions and warnings.

Cc: "Theodore Ts'o" <ty...@mit.edu>
Cc: Andreas Dilger <adilger.ker...@dilger.ca>
Cc: linux-e...@vger.kernel.org
Cc: Jan Kara <j...@suse.cz>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 fs/ext4/inode.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c94780075b04..ef21f0ad38ff 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3946,6 +3946,13 @@ static const struct address_space_operations 
ext4_da_aops = {
        .error_remove_page      = generic_error_remove_page,
 };
 
+static const struct address_space_operations ext4_dax_aops = {
+       .writepages             = ext4_writepages,
+       .direct_IO              = ext4_direct_IO,
+       .set_page_dirty         = dax_set_page_dirty,
+       .invalidatepage         = dax_invalidatepage,
+};
+
 void ext4_set_aops(struct inode *inode)
 {
        switch (ext4_inode_journal_mode(inode)) {
@@ -3958,7 +3965,9 @@ void ext4_set_aops(struct inode *inode)
        default:
                BUG();
        }
-       if (test_opt(inode->i_sb, DELALLOC))
+       if (IS_DAX(inode))
+               inode->i_mapping->a_ops = &ext4_dax_aops;
+       else if (test_opt(inode->i_sb, DELALLOC))
                inode->i_mapping->a_ops = &ext4_da_aops;
        else
                inode->i_mapping->a_ops = &ext4_aops;