Re: [PATCH RFC 6/8] fs/ext4: Update ext4_should_use_dax()

Jan Kara
2020-04-15T13:58:54Z

On Mon 13-04-20 21:00:28, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> Change the logic of ext4_should_use_dax() to support using the inode dax
> flag OR the overriding tri-state mount option.
>
> While we are at it change the function to ext4_enable_dax() as this
> better reflects the ask.

I disagree with the renaming. ext4_enable_dax() suggests it enables
something. It does not. I'd either leave ext4_should_use_dax() or maybe
change it to ext4_should_enable_dax() if you really like the "enable" word
:).

>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
> fs/ext4/inode.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index fa0ff78dc033..e9d582e516bc 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4383,9 +4383,11 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
> !ext4_test_inode_state(inode, EXT4_STATE_XATTR));
> }
>
> -static bool ext4_should_use_dax(struct inode *inode)
> +static bool ext4_enable_dax(struct inode *inode)
> {
> - if (!test_opt(inode->i_sb, DAX))
> + unsigned int flags = EXT4_I(inode)->i_flags;
> +
> + if (test_opt2(inode->i_sb, NODAX))
> return false;
> if (!S_ISREG(inode->i_mode))
> return false;
> @@ -4397,7 +4399,13 @@ static bool ext4_should_use_dax(struct inode *inode)
> return false;
> if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY))
> return false;
> - return true;
> + if (!bdev_dax_supported(inode->i_sb->s_bdev,
> + inode->i_sb->s_blocksize))
> + return false;
> + if (test_opt(inode->i_sb, DAX))
> + return true;
> +
> + return (flags & EXT4_DAX_FL) == EXT4_DAX_FL;

flags & EXT4_DAX_FL is enough here, isn't it?

Honza

> }
>
> void ext4_set_inode_flags(struct inode *inode)
> @@ -4415,7 +4423,7 @@ void ext4_set_inode_flags(struct inode *inode)
> new_fl |= S_NOATIME;
> if (flags & EXT4_DIRSYNC_FL)
> new_fl |= S_DIRSYNC;
> - if (ext4_should_use_dax(inode))
> + if (ext4_enable_dax(inode))
> new_fl |= S_DAX;
> if (flags & EXT4_ENCRYPT_FL)
> new_fl |= S_ENCRYPTED;
> --
> 2.25.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR