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

Allison Collins
2020-01-22T04:17:56Z

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
>>