Re: [PATCH v6 06/16] xfs: Factor out xfs_attr_leaf_addname helper

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

On 1/21/20 4:01 PM, Darrick J. Wong wrote:
> On Sat, Jan 18, 2020 at 03:50:25PM -0700, Allison Collins wrote:
>> Factor out new helper function xfs_attr_leaf_try_add. Because new
>> delayed attribute routines cannot roll transactions, we carve off the
>> parts of xfs_attr_leaf_addname that we can use, and move the commit into
>> the calling function.
>>
>> Signed-off-by: Allison Collins <allison.henderson@oracle.com>
>> Reviewed-by: Brian Foster <bfoster@redhat.com>
>> ---
>>   fs/xfs/libxfs/xfs_attr.c | 83 ++++++++++++++++++++++++++++--------------------
>>   1 file changed, 49 insertions(+), 34 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index b0ec25b..9ed7e94 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -305,10 +305,30 @@ xfs_attr_set_args(
>>   		}
>>   	}
>>   
>> -	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK))
>> +	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
>>   		error = xfs_attr_leaf_addname(args);
>> -	else
>> -		error = xfs_attr_node_addname(args);
>> +		if (error != -ENOSPC)
>> +			return error;
>> +
>> +		/*
>> +		 * Commit that transaction so that the node_addname()
>> +		 * call can manage its own transactions.
>> +		 */
>> +		error = xfs_defer_finish(&args->trans);
>> +		if (error)
>> +			return error;
>> +
>> +		/*
>> +		 * Commit the current trans (including the inode) and
>> +		 * start a new one.
>> +		 */
>> +		error = xfs_trans_roll_inode(&args->trans, dp);
>> +		if (error)
>> +			return error;
>> +
>> +	}
>> +
>> +	error = xfs_attr_node_addname(args);
>>   	return error;
>>   }
>>   
>> @@ -607,21 +627,12 @@ xfs_attr_shortform_addname(xfs_da_args_t *args)
>>    * External routines when attribute list is one block
>>    *========================================================================*/
>>   
>> -/*
>> - * Add a name to the leaf attribute list structure
>> - *
>> - * This leaf block cannot have a "remote" value, we only call this routine
>> - * if bmap_one_block() says there is only one block (ie: no remote blks).
>> - */
> 
> These functions are complicated enough as they are now, please make sure
> they all have comments laying out the expected input metadata states and
> what output states result from them.
> 
> I /think/ this function takes an inode whose attr data is in leaf
> format, and tries to add a new entry.  If that succeeds then we exit
> with dirty inode and transaction.  If ENOSPC then we convert the attr
> data to node format and exit w/ dirty inode + transaction, presuming
> that the caller will try again with xfs_attr_node_addname?
That sounds about right.  How about the following commentary then:
/

/* 

  * Tries to add an attribute to an inode in leaf form 

  * 

  * This function is meant to execute as part of a delayed operation and 
leaves
  * the transaction handling to the caller.  On success the attribute is 
added
  * and the inode and transaction are left dirty.  If there is not 
enough space,
  * the attr data is converted to node format and -ENOSPC is returned. 

  * Caller is responsible for handling the dirty inode and transaction 
or adding
  * the attr in node format. 

  */

Sound good?


> 
>>   STATIC int
>> -xfs_attr_leaf_addname(
>> -	struct xfs_da_args	*args)
>> +xfs_attr_leaf_try_add(
>> +	struct xfs_da_args	*args,
>> +	struct xfs_buf		*bp)
>>   {
>> -	struct xfs_buf		*bp;
>> -	int			retval, error, forkoff;
>> -	struct xfs_inode	*dp = args->dp;
>> -
>> -	trace_xfs_attr_leaf_addname(args);
>> +	int			retval, error;
>>   
>>   	/*
>>   	 * Look up the given attribute in the leaf block.  Figure out if
>> @@ -667,31 +678,35 @@ xfs_attr_leaf_addname(
>>   	retval = xfs_attr3_leaf_add(bp, args);
>>   	if (retval == -ENOSPC) {
>>   		/*
>> -		 * Promote the attribute list to the Btree format, then
>> -		 * Commit that transaction so that the node_addname() call
>> -		 * can manage its own transactions.
>> +		 * Promote the attribute list to the Btree format.
>> +		 * Unless an error occurs, retain the -ENOSPC retval
>>   		 */
>>   		error = xfs_attr3_leaf_to_node(args);
>>   		if (error)
>>   			return error;
>> -		error = xfs_defer_finish(&args->trans);
>> -		if (error)
>> -			return error;
>> +	}
>> +	return retval;
>> +}
>>   
>> -		/*
>> -		 * Commit the current trans (including the inode) and start
>> -		 * a new one.
>> -		 */
>> -		error = xfs_trans_roll_inode(&args->trans, dp);
>> -		if (error)
>> -			return error;
>>   
>> -		/*
>> -		 * Fob the whole rest of the problem off on the Btree code.
>> -		 */
>> -		error = xfs_attr_node_addname(args);
>> +/*
>> + * Add a name to the leaf attribute list structure
>> + *
>> + * This leaf block cannot have a "remote" value, we only call this routine
>> + * if bmap_one_block() says there is only one block (ie: no remote blks).
>> + */
>> +STATIC int
>> +xfs_attr_leaf_addname(struct xfs_da_args	*args)
> 
> STATIC int
> xfs_attr_leaf_addname(
> 	struct xfs_da_args	*args)
> {
> 
> Please fix the inconsistent style things as you touch them.
> 
> --D
Sure, will do.

Allison

> 
>> +{
>> +	int			error, forkoff;
>> +	struct xfs_buf		*bp = NULL;
>> +	struct xfs_inode	*dp = args->dp;
>> +
>> +	trace_xfs_attr_leaf_addname(args);
>> +
>> +	error = xfs_attr_leaf_try_add(args, bp);
>> +	if (error)
>>   		return error;
>> -	}
>>   
>>   	/*
>>   	 * Commit the transaction that added the attr name so that
>> -- 
>> 2.7.4
>>