Re: [RFC PATCH 0/4] fs: introduce new writeback error tracking infrastructure and convert ext4 to use it

[Matthew Wilcox]

On Thu, Apr 06, 2017 at 10:02:48AM +1000, NeilBrown wrote:
> If you are concerned about space in 'struct address_space', just prune
> some wastage.

I'm trying to (via wlists).  still buggy though.

> The "host" field brings no value.  It is only ever assigned in
> inode_init_always():
> 
> 	struct address_space *const mapping = &inode->i_data;
> ......
> 	mapping->host = inode;
> 
> So you could change all references to use
>    container_of(mapping, struct inode, i_data)

Alas, no:

drivers/dax/dax.c:      inode->i_mapping->host = dax_dev->inode;
fs/gfs2/glock.c:                mapping->host = s->s_bdev->bd_inode;
fs/gfs2/ops_fstype.c:   mapping->host = sb->s_bdev->bd_inode;
fs/nilfs2/page.c:       mapping->host = inode;