Re: [PATCH v3 10/19] xfs: Add xfs_attr3_leaf helper functions

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

On 9/20/19 6:50 AM, Brian Foster wrote:
> On Thu, Sep 05, 2019 at 03:18:28PM -0700, Allison Collins wrote:
>> And new helper functions xfs_attr3_leaf_flag_is_set and
>> xfs_attr3_leaf_flagsflipped.  These routines check to see
>> if xfs_attr3_leaf_setflag or xfs_attr3_leaf_flipflags have
>> already been run.  We will need this later for delayed
>> attributes since routines may be recalled several times
>> when -EAGAIN is returned.
>>
>> Signed-off-by: Allison Collins <allison.henderson@oracle.com>
>> ---
>>   fs/xfs/libxfs/xfs_attr_leaf.c | 84 +++++++++++++++++++++++++++++++++++++++++++
>>   fs/xfs/libxfs/xfs_attr_leaf.h |  2 ++
>>   2 files changed, 86 insertions(+)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
>> index bcd86c3..79650c9 100644
>> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
>> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
>> @@ -2757,6 +2757,36 @@ xfs_attr3_leaf_clearflag(
>>   }
>>   
>>   /*
>> + * Check if the INCOMPLETE flag on an entry in a leaf block is set.
>> + */
>> +int
>> +xfs_attr3_leaf_flag_is_set(
>> +	struct xfs_da_args		*args,
>> +	bool				*isset)
>> +{
>> +	struct xfs_attr_leafblock	*leaf;
>> +	struct xfs_attr_leaf_entry	*entry;
>> +	struct xfs_buf			*bp;
>> +	struct xfs_inode		*dp = args->dp;
>> +	int				error = 0;
>> +
>> +	trace_xfs_attr_leaf_setflag(args);
>> +
> 
> Tracepoint seems misplaced.. This is just a flag checking helper, right?
>
Yes, I likely scooped it up with the rest to consolidate code, but it 
probably should have stayed in setflag

>> +	/*
>> +	 * Set up the operation.
>> +	 */
> 
> Not sure what the comment means. The code seems self-explanatory here
> anyways, so you could probably just drop it.
Alrighty then, will clean out

> 
>> +	error = xfs_attr3_leaf_read(args->trans, dp, args->blkno, -1, &bp);
> 
> Didn't you create a #define for this -1 earlier in the series?
Yes, I missed applying it here.  Will fix

> 
>> +	if (error)
>> +		return error;
>> +
>> +	leaf = bp->b_addr;
>> +	entry = &xfs_attr3_leaf_entryp(leaf)[args->index];
>> +
>> +	*isset = ((entry->flags & XFS_ATTR_INCOMPLETE) != 0);
>> +	return 0;
> 
> What about bp? Should we release it before returning? If not, the
> comment above the function should elaborate.
I think you're probably right.  It's only used in the delayed code path 
and I think the logging routines may have done the release so I didn't 
notice

> 
>> +}
>> +
>> +/*
>>    * Set the INCOMPLETE flag on an entry in a leaf block.
>>    */
>>   int
>> @@ -2918,3 +2948,57 @@ xfs_attr3_leaf_flipflags(
>>   
>>   	return error;
>>   }
>> +
>> +/*
>> + * On a leaf entry, check to see if the INCOMPLETE flag is cleared
>> + * in args->blkno/index and set in args->blkno2/index2.
>> + * Note that they could be in different blocks, or in the same block.
>> + *
> 
> A sentence or two on what this check is for would be helpful. Relocation
> of an xattr or something..?
It's just a check to see if the two flags mentioned above have been 
swapped before proceeding to swap them with xfs_attr3_leaf_flipflags.  I 
believe it's used in attr renames.  I will add in some extra commentary 
to reference the other routine, that might help make a little more sense.

> 
>> + * isflipped is set to true if flags are flipped or false otherwise
>> + */
>> +int
>> +xfs_attr3_leaf_flagsflipped(
>> +	struct xfs_da_args		*args,
>> +	bool				*isflipped)
>> +{
>> +	struct xfs_attr_leafblock	*leaf1;
>> +	struct xfs_attr_leafblock	*leaf2;
>> +	struct xfs_attr_leaf_entry	*entry1;
>> +	struct xfs_attr_leaf_entry	*entry2;
>> +	struct xfs_buf			*bp1;
>> +	struct xfs_buf			*bp2;
>> +	struct xfs_inode		*dp = args->dp;
>> +	int				error = 0;
>> +
>> +	trace_xfs_attr_leaf_flipflags(args);
>> +
>> +	/*
>> +	 * Read the block containing the "old" attr
>> +	 */
>> +	error = xfs_attr3_leaf_read(args->trans, dp, args->blkno, -1, &bp1);
>> +	if (error)
>> +		return error;
>> +
> 
> Similar comments about the tracepoint, -1 usage and buffers.
Sure, will fix.  Thanks!

Allison
> 
> Brian
> 
>> +	/*
>> +	 * Read the block containing the "new" attr, if it is different
>> +	 */
>> +	if (args->blkno2 != args->blkno) {
>> +		error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno2,
>> +					   -1, &bp2);
>> +		if (error)
>> +			return error;
>> +	} else {
>> +		bp2 = bp1;
>> +	}
>> +
>> +	leaf1 = bp1->b_addr;
>> +	entry1 = &xfs_attr3_leaf_entryp(leaf1)[args->index];
>> +
>> +	leaf2 = bp2->b_addr;
>> +	entry2 = &xfs_attr3_leaf_entryp(leaf2)[args->index2];
>> +
>> +	*isflipped = (((entry1->flags & XFS_ATTR_INCOMPLETE) == 0) &&
>> +		      (entry2->flags & XFS_ATTR_INCOMPLETE));
>> +
>> +	return 0;
>> +}
>> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
>> index 58e9327..d82229b 100644
>> --- a/fs/xfs/libxfs/xfs_attr_leaf.h
>> +++ b/fs/xfs/libxfs/xfs_attr_leaf.h
>> @@ -57,7 +57,9 @@ int	xfs_attr3_leaf_to_shortform(struct xfs_buf *bp,
>>   				   struct xfs_da_args *args, int forkoff);
>>   int	xfs_attr3_leaf_clearflag(struct xfs_da_args *args);
>>   int	xfs_attr3_leaf_setflag(struct xfs_da_args *args);
>> +int	xfs_attr3_leaf_flag_is_set(struct xfs_da_args *args, bool *isset);
>>   int	xfs_attr3_leaf_flipflags(struct xfs_da_args *args);
>> +int	xfs_attr3_leaf_flagsflipped(struct xfs_da_args *args, bool *isflipped);
>>   
>>   /*
>>    * Routines used for growing the Btree.
>> -- 
>> 2.7.4
>>