ext2, dax: introduce ext2_dax_aops

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.

Reviewed-by: Jan Kara <jack@suse.com>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

3 files changed, 30 insertions, 35 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..1e01fabef130 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -940,9 +940,6 @@ ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
         loff_t offset = iocb->ki_pos;
         ssize_t ret;
 
-        if (WARN_ON_ONCE(IS_DAX(inode)))
-                return -EIO;
-
         ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
         if (ret < 0 && iov_iter_rw(iter) == WRITE)
                 ext2_write_failed(mapping, offset + count);
@@ -952,17 +949,16 @@ ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 static int
 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
-#ifdef CONFIG_FS_DAX
-        if (dax_mapping(mapping)) {
-                return dax_writeback_mapping_range(mapping,
-                                                   mapping->host->i_sb->s_bdev,
-                                                   wbc);
-        }
-#endif
-
         return mpage_writepages(mapping, wbc, ext2_get_block);
 }
 
+static int
+ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+        return dax_writeback_mapping_range(mapping,
+                        mapping->host->i_sb->s_bdev, wbc);
+}
+
 const struct address_space_operations ext2_aops = {
         .readpage               = ext2_readpage,
         .readpages              = ext2_readpages,
@@ -990,6 +986,13 @@ const struct address_space_operations ext2_nobh_aops = {
         .error_remove_page      = generic_error_remove_page,
 };
 
+static const struct address_space_operations ext2_dax_aops = {
+        .writepages             = ext2_dax_writepages,
+        .direct_IO              = noop_direct_IO,
+        .set_page_dirty         = noop_set_page_dirty,
+        .invalidatepage         = noop_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 +1391,18 @@ 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 +1495,7 @@ 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);