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

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" <>
Cc: Andreas Dilger <>
Reviewed-by: 's avatarJan Kara <>
Signed-off-by: 's avatarDan Williams <>
parent 6e2608df
......@@ -2725,12 +2725,6 @@ static int ext4_writepages(struct address_space *mapping,
trace_ext4_writepages(inode, wbc);
if (dax_mapping(mapping)) {
ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
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;
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);
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)
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;
inode->i_mapping->a_ops = &ext4_aops;
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