Re: [PATCH v13 06/10] xfs: Add xfs_attr_set_deferred and xfs_attr_remove_deferred

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Thu, Oct 22, 2020 at 11:34:31PM -0700, Allison Henderson wrote:
> From: Allison Collins <allison.henderson@oracle.com>
> 
> These routines to set up and start a new deferred attribute operations.
> These functions are meant to be called by any routine needing to
> initiate a deferred attribute operation as opposed to the existing
> inline operations. New helper function xfs_attr_item_init also added.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_attr.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/libxfs/xfs_attr.h |  2 ++
>  2 files changed, 56 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 760383c..7fe5554 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -25,6 +25,7 @@
>  #include "xfs_trans_space.h"
>  #include "xfs_trace.h"
>  #include "xfs_attr_item.h"
> +#include "xfs_attr.h"
>  
>  /*
>   * xfs_attr.c
> @@ -643,6 +644,59 @@ xfs_attr_set(
>  	goto out_unlock;
>  }
>  
> +STATIC int
> +xfs_attr_item_init(
> +	struct xfs_da_args	*args,
> +	unsigned int		op_flags,	/* op flag (set or remove) */
> +	struct xfs_attr_item	**attr)		/* new xfs_attr_item */
> +{
> +
> +	struct xfs_attr_item	*new;
> +
> +	new = kmem_alloc_large(sizeof(struct xfs_attr_item), KM_NOFS);

I don't think we need _large allocations for struct xfs_attr_item, right?

> +	memset(new, 0, sizeof(struct xfs_attr_item));

Use kmem_zalloc and you won't have to memset.  Better yet, zalloc will
get you memory that's been pre-zeroed in the background.

> +	new->xattri_op_flags = op_flags;
> +	new->xattri_dac.da_args = args;
> +
> +	*attr = new;
> +	return 0;
> +}
> +
> +/* Sets an attribute for an inode as a deferred operation */
> +int
> +xfs_attr_set_deferred(
> +	struct xfs_da_args	*args)
> +{
> +	struct xfs_attr_item	*new;
> +	int			error = 0;
> +
> +	error = xfs_attr_item_init(args, XFS_ATTR_OP_FLAGS_SET, &new);
> +	if (error)
> +		return error;
> +
> +	xfs_defer_add(args->trans, XFS_DEFER_OPS_TYPE_ATTR, &new->xattri_list);
> +
> +	return 0;
> +}

The changes in "xfs: enable delayed attributes" should be moved to this
patch so that these new functions immediately have callers.

(Also see the reply I sent to the next patch, which will avoid weird
regressions if someone's bisect lands in the middle of this series...)

--D

> +
> +/* Removes an attribute for an inode as a deferred operation */
> +int
> +xfs_attr_remove_deferred(
> +	struct xfs_da_args	*args)
> +{
> +
> +	struct xfs_attr_item	*new;
> +	int			error;
> +
> +	error  = xfs_attr_item_init(args, XFS_ATTR_OP_FLAGS_REMOVE, &new);
> +	if (error)
> +		return error;
> +
> +	xfs_defer_add(args->trans, XFS_DEFER_OPS_TYPE_ATTR, &new->xattri_list);
> +
> +	return 0;
> +}
> +
>  /*========================================================================
>   * External routines when attribute list is inside the inode
>   *========================================================================*/
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 5b4a1ca..8a08411 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -307,5 +307,7 @@ bool xfs_attr_namecheck(const void *name, size_t length);
>  void xfs_delattr_context_init(struct xfs_delattr_context *dac,
>  			      struct xfs_da_args *args);
>  int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
> +int xfs_attr_set_deferred(struct xfs_da_args *args);
> +int xfs_attr_remove_deferred(struct xfs_da_args *args);
>  
>  #endif	/* __XFS_ATTR_H__ */
> -- 
> 2.7.4
>