Re: [PATCH v16 06/11] xfs: Add helper xfs_attr_node_addname_find_attr

[Chandan Babu R <chandanrlinux@gmail.com>]

On 26 Mar 2021 at 06:03, Allison Henderson wrote:
> This patch separates the first half of xfs_attr_node_addname into a
> helper function xfs_attr_node_addname_find_attr.  It also replaces the
> restart goto with with an EAGAIN return code driven by a loop in the
> calling function.  This looks odd now, but will clean up nicly once we
> introduce the state machine.  It will also enable hoisting the last
> state out of xfs_attr_node_addname with out having to plumb in a "done"
> parameter to know if we need to move to the next state or not.
>

Looks good to me.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  fs/xfs/libxfs/xfs_attr.c | 86 ++++++++++++++++++++++++++++++------------------
>  1 file changed, 54 insertions(+), 32 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 531ff56..16159f6 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -52,7 +52,10 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>   * Internal routines when attribute list is more than one block.
>   */
>  STATIC int xfs_attr_node_get(xfs_da_args_t *args);
> -STATIC int xfs_attr_node_addname(xfs_da_args_t *args);
> +STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
> +				 struct xfs_da_state *state);
> +STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
> +				 struct xfs_da_state **state);
>  STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
>  STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
>  STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
> @@ -267,6 +270,7 @@ xfs_attr_set_args(
>  	struct xfs_da_args	*args)
>  {
>  	struct xfs_inode	*dp = args->dp;
> +	struct xfs_da_state     *state;
>  	int			error;
>  
>  	/*
> @@ -312,7 +316,14 @@ xfs_attr_set_args(
>  			return error;
>  	}
>  
> -	return xfs_attr_node_addname(args);
> +	do {
> +		error = xfs_attr_node_addname_find_attr(args, &state);
> +		if (error)
> +			return error;
> +		error = xfs_attr_node_addname(args, state);
> +	} while (error == -EAGAIN);
> +
> +	return error;
>  }
>  
>  /*
> @@ -885,47 +896,26 @@ xfs_attr_node_hasname(
>   * External routines when attribute list size > geo->blksize
>   *========================================================================*/
>  
> -/*
> - * Add a name to a Btree-format attribute list.
> - *
> - * This will involve walking down the Btree, and may involve splitting
> - * leaf nodes and even splitting intermediate nodes up to and including
> - * the root node (a special case of an intermediate node).
> - *
> - * "Remote" attribute values confuse the issue and atomic rename operations
> - * add a whole extra layer of confusion on top of that.
> - */
>  STATIC int
> -xfs_attr_node_addname(
> -	struct xfs_da_args	*args)
> +xfs_attr_node_addname_find_attr(
> +	struct xfs_da_args	*args,
> +	struct xfs_da_state     **state)
>  {
> -	struct xfs_da_state	*state;
> -	struct xfs_da_state_blk	*blk;
> -	struct xfs_inode	*dp;
> -	int			retval, error;
> -
> -	trace_xfs_attr_node_addname(args);
> +	int			retval;
>  
>  	/*
> -	 * Fill in bucket of arguments/results/context to carry around.
> -	 */
> -	dp = args->dp;
> -restart:
> -	/*
>  	 * Search to see if name already exists, and get back a pointer
>  	 * to where it should go.
>  	 */
> -	retval = xfs_attr_node_hasname(args, &state);
> +	retval = xfs_attr_node_hasname(args, state);
>  	if (retval != -ENOATTR && retval != -EEXIST)
> -		goto out;
> +		goto error;
>  
> -	blk = &state->path.blk[ state->path.active-1 ];
> -	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
>  	if (retval == -ENOATTR && (args->attr_flags & XATTR_REPLACE))
> -		goto out;
> +		goto error;
>  	if (retval == -EEXIST) {
>  		if (args->attr_flags & XATTR_CREATE)
> -			goto out;
> +			goto error;
>  
>  		trace_xfs_attr_node_replace(args);
>  
> @@ -943,6 +933,38 @@ xfs_attr_node_addname(
>  		args->rmtvaluelen = 0;
>  	}
>  
> +	return 0;
> +error:
> +	if (*state)
> +		xfs_da_state_free(*state);
> +	return retval;
> +}
> +
> +/*
> + * Add a name to a Btree-format attribute list.
> + *
> + * This will involve walking down the Btree, and may involve splitting
> + * leaf nodes and even splitting intermediate nodes up to and including
> + * the root node (a special case of an intermediate node).
> + *
> + * "Remote" attribute values confuse the issue and atomic rename operations
> + * add a whole extra layer of confusion on top of that.
> + */
> +STATIC int
> +xfs_attr_node_addname(
> +	struct xfs_da_args	*args,
> +	struct xfs_da_state	*state)
> +{
> +	struct xfs_da_state_blk	*blk;
> +	struct xfs_inode	*dp;
> +	int			retval, error;
> +
> +	trace_xfs_attr_node_addname(args);
> +
> +	dp = args->dp;
> +	blk = &state->path.blk[state->path.active-1];
> +	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
> +
>  	retval = xfs_attr3_leaf_add(blk->bp, state->args);
>  	if (retval == -ENOSPC) {
>  		if (state->path.active == 1) {
> @@ -968,7 +990,7 @@ xfs_attr_node_addname(
>  			if (error)
>  				goto out;
>  
> -			goto restart;
> +			return -EAGAIN;
>  		}
>  
>  		/*


-- 
chandan