[PATCH v5 04/11] ext2, dax: introduce ext2_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: Jan Kara <j...@suse.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 fs/ext2/ext2.h  |    1 +
 fs/ext2/inode.c |   28 ++++++++++++++++++++--------
 fs/ext2/namei.c |   18 ++----------------
 3 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 032295e1d386..cc40802ddfa8 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -814,6 +814,7 @@ extern const struct inode_operations 
ext2_file_inode_operations;
 extern const struct file_operations ext2_file_operations;
 
 /* inode.c */
+extern void ext2_set_file_ops(struct inode *inode);
 extern const struct address_space_operations ext2_aops;
 extern const struct address_space_operations ext2_nobh_aops;
 extern const struct iomap_ops ext2_iomap_ops;
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 9b2ac55ac34f..09608f7e9e39 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -990,6 +990,13 @@ const struct address_space_operations ext2_nobh_aops = {
        .error_remove_page      = generic_error_remove_page,
 };
 
+const struct address_space_operations ext2_dax_aops = {
+       .writepages             = ext2_writepages,
+       .direct_IO              = ext2_direct_IO,
+       .set_page_dirty         = dax_set_page_dirty,
+       .invalidatepage         = dax_invalidatepage,
+};
+
 /*
  * Probably it should be a library function... search for first non-zero word
  * or memcmp with zero_page, whatever is better for particular architecture.
@@ -1388,6 +1395,18 @@ void ext2_set_inode_flags(struct inode *inode)
                inode->i_flags |= S_DAX;
 }
 
+void ext2_set_file_ops(struct inode *inode)
+{
+       inode->i_op = &ext2_file_inode_operations;
+       inode->i_fop = &ext2_file_operations;
+       if (IS_DAX(inode))
+               inode->i_mapping->a_ops = &ext2_dax_aops;
+       else if (test_opt(inode->i_sb, NOBH))
+               inode->i_mapping->a_ops = &ext2_nobh_aops;
+       else
+               inode->i_mapping->a_ops = &ext2_aops;
+}
+
 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
 {
        struct ext2_inode_info *ei;
@@ -1480,14 +1499,7 @@ struct inode *ext2_iget (struct super_block *sb, 
unsigned long ino)
                ei->i_data[n] = raw_inode->i_block[n];
 
        if (S_ISREG(inode->i_mode)) {
-               inode->i_op = &ext2_file_inode_operations;
-               if (test_opt(inode->i_sb, NOBH)) {
-                       inode->i_mapping->a_ops = &ext2_nobh_aops;
-                       inode->i_fop = &ext2_file_operations;
-               } else {
-                       inode->i_mapping->a_ops = &ext2_aops;
-                       inode->i_fop = &ext2_file_operations;
-               }
+               ext2_set_file_ops(inode);
        } else if (S_ISDIR(inode->i_mode)) {
                inode->i_op = &ext2_dir_inode_operations;
                inode->i_fop = &ext2_dir_operations;
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index e078075dc66f..55f7caadb093 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -107,14 +107,7 @@ static int ext2_create (struct inode * dir, struct dentry 
* dentry, umode_t mode
        if (IS_ERR(inode))
                return PTR_ERR(inode);
 
-       inode->i_op = &ext2_file_inode_operations;
-       if (test_opt(inode->i_sb, NOBH)) {
-               inode->i_mapping->a_ops = &ext2_nobh_aops;
-               inode->i_fop = &ext2_file_operations;
-       } else {
-               inode->i_mapping->a_ops = &ext2_aops;
-               inode->i_fop = &ext2_file_operations;
-       }
+       ext2_set_file_ops(inode);
        mark_inode_dirty(inode);
        return ext2_add_nondir(dentry, inode);
 }
@@ -125,14 +118,7 @@ static int ext2_tmpfile(struct inode *dir, struct dentry 
*dentry, umode_t mode)
        if (IS_ERR(inode))
                return PTR_ERR(inode);
 
-       inode->i_op = &ext2_file_inode_operations;
-       if (test_opt(inode->i_sb, NOBH)) {
-               inode->i_mapping->a_ops = &ext2_nobh_aops;
-               inode->i_fop = &ext2_file_operations;
-       } else {
-               inode->i_mapping->a_ops = &ext2_aops;
-               inode->i_fop = &ext2_file_operations;
-       }
+       ext2_set_file_ops(inode);
        mark_inode_dirty(inode);
        d_tmpfile(dentry, inode);
        unlock_new_inode(inode);