Christoph Hellwig <hch@xxxxxx> writes:
> Since commit a2ad63daa88b ("VFS: add FMODE_CAN_ODIRECT file flag") file
> systems can just set the FMODE_CAN_ODIRECT flag at open time instead of
> wiring up a dummy direct_IO method to indicate support for direct I/O.
>
> Do that for ext4 so that noop_direct_IO can eventually be removed.
Looks straight forward change to me.
However I got some query...
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 02de439bf1f04e..b9c1cfa1864779 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3573,7 +3571,6 @@ static const struct address_space_operations ext4_da_aops = {
> .bmap = ext4_bmap,
> .invalidate_folio = ext4_invalidate_folio,
> .release_folio = ext4_release_folio,
> - .direct_IO = noop_direct_IO,
> .migrate_folio = buffer_migrate_folio,
> .is_partially_uptodate = block_is_partially_uptodate,
> .error_remove_page = generic_error_remove_page,
> @@ -3582,7 +3579,6 @@ static const struct address_space_operations ext4_da_aops = {
>
> static const struct address_space_operations ext4_dax_aops = {
> .writepages = ext4_dax_writepages,
> - .direct_IO = noop_direct_IO,
> .dirty_folio = noop_dirty_folio,
> .bmap = ext4_bmap,
> .swap_activate = ext4_iomap_swap_activate,
why do we require .direct_IO function op for any of the dax_aops?
IIUC, any inode if it supports DAX i.e. IS_DAX(inode), then it takes the
separate path in file read/write iter path.
so it should never do ->direct_IO on an inode which supports DAX right?
Maybe I am missing something and I will have to check when does
->direct_IO gets called for DAX...
... Or is it due to CONFIG_FS_DAX?
e.g.
ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct inode *inode = file_inode(iocb->ki_filp);
if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
return -EIO;
#ifdef CONFIG_FS_DAX
if (IS_DAX(inode))
return ext4_dax_write_iter(iocb, from);
#endif
if (iocb->ki_flags & IOCB_DIRECT)
return ext4_dio_write_iter(iocb, from);
else
return ext4_buffered_write_iter(iocb, from);
}
-ritesh
