Re: [PATCH v16 04/11] xfs: Add helper xfs_attr_set_fmt

[Allison Henderson <allison.henderson@xxxxxxxxxx>]

On 3/29/21 2:37 AM, Chandan Babu R wrote:
> On 26 Mar 2021 at 06:03, Allison Henderson wrote:
> > This patch adds a helper function xfs_attr_set_fmt.  This will help
> > isolate the code that will require state management from the portions
> > that do not.  xfs_attr_set_fmt returns 0 when the attr has been set and
> > no further action is needed.  It returns -EAGAIN when shortform has been
> > transformed to leaf, and the calling function should proceed the set the
> > attr in leaf form.
>
> The previous behaviour is maintained across the changes made by this patch.
>
> Reviewed-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
Great, thanks for the review!
Allison

> > Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
> > Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> >
> > ---
> >   fs/xfs/libxfs/xfs_attr.c | 79 ++++++++++++++++++++++++++++--------------------
> >   1 file changed, 46 insertions(+), 33 deletions(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > index 5216f67..d46324a 100644
> > --- a/fs/xfs/libxfs/xfs_attr.c
> > +++ b/fs/xfs/libxfs/xfs_attr.c
> > @@ -216,6 +216,48 @@ xfs_attr_is_shortform(
> >   		ip->i_afp->if_nextents == 0);
> >   }
> >   
> > +STATIC int
> > +xfs_attr_set_fmt(
> > +	struct xfs_da_args	*args)
> > +{
> > +	struct xfs_buf          *leaf_bp = NULL;
> > +	struct xfs_inode	*dp = args->dp;
> > +	int			error2, error = 0;
> > +
> > +	/*
> > +	 * Try to add the attr to the attribute list in the inode.
> > +	 */
> > +	error = xfs_attr_try_sf_addname(dp, args);
> > +	if (error != -ENOSPC) {
> > +		error2 = xfs_trans_commit(args->trans);
> > +		args->trans = NULL;
> > +		return error ? error : error2;
> > +	}
> > +
> > +	/*
> > +	 * It won't fit in the shortform, transform to a leaf block.
> > +	 * GROT: another possible req'mt for a double-split btree op.
> > +	 */
> > +	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> > +	if (error)
> > +		return error;
> > +
> > +	/*
> > +	 * Prevent the leaf buffer from being unlocked so that a
> > +	 * concurrent AIL push cannot grab the half-baked leaf buffer
> > +	 * and run into problems with the write verifier.
> > +	 */
> > +	xfs_trans_bhold(args->trans, leaf_bp);
> > +	error = xfs_defer_finish(&args->trans);
> > +	xfs_trans_bhold_release(args->trans, leaf_bp);
> > +	if (error) {
> > +		xfs_trans_brelse(args->trans, leaf_bp);
> > +		return error;
> > +	}
> > +
> > +	return -EAGAIN;
> > +}
> > +
> >   /*
> >    * Set the attribute specified in @args.
> >    */
> > @@ -224,8 +266,7 @@ xfs_attr_set_args(
> >   	struct xfs_da_args	*args)
> >   {
> >   	struct xfs_inode	*dp = args->dp;
> > -	struct xfs_buf          *leaf_bp = NULL;
> > -	int			error2, error = 0;
> > +	int			error;
> >   
> >   	/*
> >   	 * If the attribute list is already in leaf format, jump straight to
> > @@ -234,36 +275,9 @@ xfs_attr_set_args(
> >   	 * again.
> >   	 */
> >   	if (xfs_attr_is_shortform(dp)) {
> > -		/*
> > -		 * Try to add the attr to the attribute list in the inode.
> > -		 */
> > -		error = xfs_attr_try_sf_addname(dp, args);
> > -		if (error != -ENOSPC) {
> > -			error2 = xfs_trans_commit(args->trans);
> > -			args->trans = NULL;
> > -			return error ? error : error2;
> > -		}
> > -
> > -		/*
> > -		 * It won't fit in the shortform, transform to a leaf block.
> > -		 * GROT: another possible req'mt for a double-split btree op.
> > -		 */
> > -		error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> > -		if (error)
> > -			return error;
> > -
> > -		/*
> > -		 * Prevent the leaf buffer from being unlocked so that a
> > -		 * concurrent AIL push cannot grab the half-baked leaf buffer
> > -		 * and run into problems with the write verifier.
> > -		 */
> > -		xfs_trans_bhold(args->trans, leaf_bp);
> > -		error = xfs_defer_finish(&args->trans);
> > -		xfs_trans_bhold_release(args->trans, leaf_bp);
> > -		if (error) {
> > -			xfs_trans_brelse(args->trans, leaf_bp);
> > +		error = xfs_attr_set_fmt(args);
> > +		if (error != -EAGAIN)
> >   			return error;
> > -		}
> >   	}
> >   
> >   	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> > @@ -297,8 +311,7 @@ xfs_attr_set_args(
> >   			return error;
> >   	}
> >   
> > -	error = xfs_attr_node_addname(args);
> > -	return error;
> > +	return xfs_attr_node_addname(args);
> >   }
> >   
> >   /*