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Commit 5f0663bb authored by Dan Williams's avatar Dan Williams
Browse files

ext4, dax: introduce ext4_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.

Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: linux-ext4@vger.kernel.org
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 6e2608df

fs/ext4/inode.c

+31 −11
Original line number Diff line number Diff line
@@ -2725,12 +2725,6 @@ static int ext4_writepages(struct address_space *mapping, 
	percpu_down_read(&sbi->s_journal_flag_rwsem);

	trace_ext4_writepages(inode, wbc);



	if (dax_mapping(mapping)) {

		ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,

						  wbc);

		goto out_writepages;

	}



	/*

	 * No pages to write? This is mainly a kludge to avoid starting

	 * a transaction for special inodes like journal inode on last iput()
@@ -2955,6 +2949,27 @@ static int ext4_writepages(struct address_space *mapping, 
	return ret;

}



static int ext4_dax_writepages(struct address_space *mapping,

			       struct writeback_control *wbc)

{

	int ret;

	long nr_to_write = wbc->nr_to_write;

	struct inode *inode = mapping->host;

	struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);



	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))

		return -EIO;



	percpu_down_read(&sbi->s_journal_flag_rwsem);

	trace_ext4_writepages(inode, wbc);



	ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);

	trace_ext4_writepages_result(inode, wbc, ret,

				     nr_to_write - wbc->nr_to_write);

	percpu_up_read(&sbi->s_journal_flag_rwsem);

	return ret;

}



static int ext4_nonda_switch(struct super_block *sb)

{

	s64 free_clusters, dirty_clusters;
@@ -3857,10 +3872,6 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter) 
	if (ext4_has_inline_data(inode))

		return 0;



	/* DAX uses iomap path now */

	if (WARN_ON_ONCE(IS_DAX(inode)))

		return 0;



	trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));

	if (iov_iter_rw(iter) == READ)

		ret = ext4_direct_IO_read(iocb, iter);
@@ -3946,6 +3957,13 @@ 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_dax_writepages,

	.direct_IO		= noop_direct_IO,

	.set_page_dirty		= noop_set_page_dirty,

	.invalidatepage		= noop_invalidatepage,

};



void ext4_set_aops(struct inode *inode)

{

	switch (ext4_inode_journal_mode(inode)) {
@@ -3958,7 +3976,9 @@ 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;