Re: [PATCH v22 16/16] xfs: Add helper function xfs_attr_leaf_addname

[Allison Henderson <allison.henderson@oracle.com>]

On 7/28/21 12:52 PM, Darrick J. Wong wrote:
> On Mon, Jul 26, 2021 at 11:20:53PM -0700, Allison Henderson wrote:
>> This patch adds a helper function xfs_attr_leaf_addname.  While this
>> does help to break down xfs_attr_set_iter, it does also hoist out some
>> of the state management.  This patch has been moved to the end of the
>> clean up series for further discussion.
>>
>> Suggested-by: Darrick J. Wong <djwong@kernel.org>
>> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
>> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
>> ---
>>   fs/xfs/libxfs/xfs_attr.c | 108 ++++++++++++++++++++++++++---------------------
>>   fs/xfs/xfs_trace.h       |   1 +
>>   2 files changed, 61 insertions(+), 48 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index 811288d..acb995b 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -285,6 +285,65 @@ xfs_attr_sf_addname(
>>   	return -EAGAIN;
>>   }
>>   
>> +STATIC int
>> +xfs_attr_leaf_addname(
>> +	struct xfs_attr_item	*attr)
>> +{
>> +	struct xfs_da_args	*args = attr->xattri_da_args;
>> +	struct xfs_buf		*leaf_bp = attr->xattri_leaf_bp;
>> +	struct xfs_inode	*dp = args->dp;
>> +	int			error;
>> +
>> +	if (xfs_attr_is_leaf(dp)) {
>> +		error = xfs_attr_leaf_try_add(args, leaf_bp);
>> +		if (error == -ENOSPC) {
>> +			error = xfs_attr3_leaf_to_node(args);
>> +			if (error)
>> +				return error;
>> +
>> +			/*
>> +			 * Finish any deferred work items and roll the
>> +			 * transaction once more.  The goal here is to call
>> +			 * node_addname with the inode and transaction in the
>> +			 * same state (inode locked and joined, transaction
>> +			 * clean) no matter how we got to this step.
>> +			 *
>> +			 * At this point, we are still in XFS_DAS_UNINIT, but
>> +			 * when we come back, we'll be a node, so we'll fall
>> +			 * down into the node handling code below
>> +			 */
>> +			trace_xfs_attr_set_iter_return(
>> +				attr->xattri_dela_state, args->dp);
>> +			return -EAGAIN;
>> +		}
>> +
>> +		if (error)
>> +			return error;
>> +
>> +		attr->xattri_dela_state = XFS_DAS_FOUND_LBLK;
> 
> Hmm.  I know I reviewed this once before, but on second thought it's a
> little strange to be calling the node addname function from the leaf
> addname function.  Can you reduce the leaf addname function's scope like
> this:
> 
> STATIC int
> xfs_attr_leaf_addname(
> 	struct xfs_attr_item	*attr)
> 
> 	struct xfs_da_args	*args = attr->xattri_da_args;
> 	struct xfs_buf		*leaf_bp = attr->xattri_leaf_bp;
> 	struct xfs_inode	*dp = args->dp;
> 	int			error;
> 
> 	error = xfs_attr_leaf_try_add(args, leaf_bp);
> 	if (error == 0) {
> 		attr->xattri_dela_state = XFS_DAS_FOUND_LBLK;
> 		trace_xfs_attr_leaf_addname_return(attr->xattri_dela_state,
> 				args->dp);
> 		return -EAGAIN;
> 	}
> 	if (error != -ENOSPC)
> 		return error;
> 
> 	/* No room in leaf; convert to node format and try again. */
> 	error = xfs_attr3_leaf_to_node(args);
> 	if (error)
> 		return error;
> 
> 	/*
> 	 * Finish any deferred work items and roll the transaction once
> 	 * more.  The goal here is to call node_addname with the inode
> 	 * and transaction in the same state (inode locked and joined,
> 	 * transaction clean) no matter how we got to this step.
> 	 *
> 	 * At this point, we are still in XFS_DAS_UNINIT, but when we
> 	 * come back, we'll be a node, so we'll fall down into the node
> 	 * handling code below
> 	 */
> 	trace_xfs_attr_set_iter_return(attr->xattri_dela_state,
> 			args->dp);
> 	return -EAGAIN;
> }
> 
> Then the callsite up in xfs_attr_set_iter looks like:
> 
> 	case XFS_DAS_UNINIT:
> 		if (xfs_attr_is_shortform(dp))
> 			return xfs_attr_sf_addname(dac, leaf_bp);
> 		if (*leaf_bp != NULL) {
> 			xfs_trans_bhold_release(args->trans, *leaf_bp);
> 			*leaf_bp = NULL;
> 		}
> 
> 		if (xfs_attr_is_leaf(dp))
> 			return xfs_attr_leaf_addname(...);
> 
> 		/* node format */
> 		error = xfs_attr_node_addname_find_attr(attr);
> 		if (error)
> 			return error;
> 
> 		error = xfs_attr_node_addname(attr);
> 		if (error)
> 			return error;
> 
> 		dac->dela_state = XFS_DAS_FOUND_NBLK;
> 		return -EAGAIN;
> 
> 	case XFS_DAS_FOUND_LBLK:
> 
Sure, I can pull some of that back up, should be ok.

Allison

> --D
> 
>> +	} else {
>> +		error = xfs_attr_node_addname_find_attr(attr);
>> +		if (error)
>> +			return error;
>> +
>> +		error = xfs_attr_node_addname(attr);
>> +		if (error)
>> +			return error;
>> +
>> +		/*
>> +		 * If addname was successful, and we dont need to alloc or
>> +		 * remove anymore blks, we're done.
>> +		 */
>> +		if (!args->rmtblkno && !args->rmtblkno2)
>> +			return 0;
>> +
>> +		attr->xattri_dela_state = XFS_DAS_FOUND_NBLK;
>> +	}
>> +
>> +	trace_xfs_attr_leaf_addname_return(attr->xattri_dela_state, args->dp);
>> +	return -EAGAIN;
>> +}
>> +
>>   /*
>>    * Set the attribute specified in @args.
>>    * This routine is meant to function as a delayed operation, and may return
>> @@ -320,55 +379,8 @@ xfs_attr_set_iter(
>>   			*leaf_bp = NULL;
>>   		}
>>   
>> -		if (xfs_attr_is_leaf(dp)) {
>> -			error = xfs_attr_leaf_try_add(args, *leaf_bp);
>> -			if (error == -ENOSPC) {
>> -				error = xfs_attr3_leaf_to_node(args);
>> -				if (error)
>> -					return error;
>> -
>> -				/*
>> -				 * Finish any deferred work items and roll the
>> -				 * transaction once more.  The goal here is to
>> -				 * call node_addname with the inode and
>> -				 * transaction in the same state (inode locked
>> -				 * and joined, transaction clean) no matter how
>> -				 * we got to this step.
>> -				 *
>> -				 * At this point, we are still in
>> -				 * XFS_DAS_UNINIT, but when we come back, we'll
>> -				 * be a node, so we'll fall down into the node
>> -				 * handling code below
>> -				 */
>> -				trace_xfs_attr_set_iter_return(
>> -					attr->xattri_dela_state, args->dp);
>> -				return -EAGAIN;
>> -			} else if (error) {
>> -				return error;
>> -			}
>> -
>> -			attr->xattri_dela_state = XFS_DAS_FOUND_LBLK;
>> -		} else {
>> -			error = xfs_attr_node_addname_find_attr(attr);
>> -			if (error)
>> -				return error;
>> +		return xfs_attr_leaf_addname(attr);
>>   
>> -			error = xfs_attr_node_addname(attr);
>> -			if (error)
>> -				return error;
>> -
>> -			/*
>> -			 * If addname was successful, and we dont need to alloc
>> -			 * or remove anymore blks, we're done.
>> -			 */
>> -			if (!args->rmtblkno && !args->rmtblkno2)
>> -				return 0;
>> -
>> -			attr->xattri_dela_state = XFS_DAS_FOUND_NBLK;
>> -		}
>> -		trace_xfs_attr_set_iter_return(attr->xattri_dela_state,
>> -					       args->dp);
>> -		return -EAGAIN;
>>   	case XFS_DAS_FOUND_LBLK:
>>   		/*
>>   		 * If there was an out-of-line value, allocate the blocks we
>> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
>> index f9840dd..cf8bd3a 100644
>> --- a/fs/xfs/xfs_trace.h
>> +++ b/fs/xfs/xfs_trace.h
>> @@ -4008,6 +4008,7 @@ DEFINE_EVENT(xfs_das_state_class, name, \
>>   	TP_ARGS(das, ip))
>>   DEFINE_DAS_STATE_EVENT(xfs_attr_sf_addname_return);
>>   DEFINE_DAS_STATE_EVENT(xfs_attr_set_iter_return);
>> +DEFINE_DAS_STATE_EVENT(xfs_attr_leaf_addname_return);
>>   DEFINE_DAS_STATE_EVENT(xfs_attr_node_addname_return);
>>   DEFINE_DAS_STATE_EVENT(xfs_attr_remove_iter_return);
>>   DEFINE_DAS_STATE_EVENT(xfs_attr_rmtval_remove_return);
>> -- 
>> 2.7.4
>>