On Sat, Dec 23, 2017 at 04:57:04PM -0800, Dan Williams wrote:
> 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: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
> Cc: linux-xfs@xxxxxxxxxxxxxxx
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> fs/xfs/xfs_aops.c | 2 ++
> fs/xfs/xfs_aops.h | 1 +
> fs/xfs/xfs_iops.c | 5 ++++-
> 3 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 21e2d70884e1..361915d53cef 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -1492,3 +1492,5 @@ const struct address_space_operations xfs_address_space_operations = {
> .is_partially_uptodate = block_is_partially_uptodate,
> .error_remove_page = generic_error_remove_page,
> };
> +
> +DEFINE_FSDAX_AOPS(xfs_dax_address_space_operations, xfs_vm_writepages);
Hmm, if we ever re-enable changing the DAX flag on the fly, will
mapping->a_ops have to change dynamically too?
How sure are we that we'll never have to set anything in the dax aops
other than ->writepages?
(I also kinda wonder why not just make the callers savvy vs. a bunch of
dummy aops, but maybe that's been tried in a previous iteration?)
--D
> diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h
> index 88c85ea63da0..a6ffbb5fe379 100644
> --- a/fs/xfs/xfs_aops.h
> +++ b/fs/xfs/xfs_aops.h
> @@ -54,6 +54,7 @@ struct xfs_ioend {
> };
>
> extern const struct address_space_operations xfs_address_space_operations;
> +extern const struct address_space_operations xfs_dax_address_space_operations;
>
> int xfs_setfilesize(struct xfs_inode *ip, xfs_off_t offset, size_t size);
>
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 56475fcd76f2..67bd97edc73b 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -1272,7 +1272,10 @@ xfs_setup_iops(
> case S_IFREG:
> inode->i_op = &xfs_inode_operations;
> inode->i_fop = &xfs_file_operations;
> - inode->i_mapping->a_ops = &xfs_address_space_operations;
> + if (IS_DAX(inode))
> + inode->i_mapping->a_ops = &xfs_dax_address_space_operations;
> + else
> + inode->i_mapping->a_ops = &xfs_address_space_operations;
> break;
> case S_IFDIR:
> if (xfs_sb_version_hasasciici(&XFS_M(inode->i_sb)->m_sb))
>
> --
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