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

Allison Henderson
2021-08-02T08:18:49Z

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
>>