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Message-ID: <20250502200646.GT25675@frogsfrogsfrogs>
Date: Fri, 2 May 2025 13:06:46 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: Hans Holmberg <Hans.Holmberg@....com>
Cc: "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
Carlos Maiolino <cem@...nel.org>,
Dave Chinner <david@...morbit.com>, hch <hch@....de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] xfs: free the item in xfs_mru_cache_insert on
failure
On Wed, Apr 30, 2025 at 08:41:21AM +0000, Hans Holmberg wrote:
> From: Christoph Hellwig <hch@....de>
>
> Call the provided free_func when xfs_mru_cache_insert as that's what
> the callers need to do anyway.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
> Signed-off-by: Hans Holmberg <hans.holmberg@....com>
> ---
> fs/xfs/xfs_filestream.c | 15 ++++-----------
> fs/xfs/xfs_mru_cache.c | 15 ++++++++++++---
> 2 files changed, 16 insertions(+), 14 deletions(-)
>
> diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
> index a961aa420c48..044918fbae06 100644
> --- a/fs/xfs/xfs_filestream.c
> +++ b/fs/xfs/xfs_filestream.c
> @@ -304,11 +304,9 @@ xfs_filestream_create_association(
> * for us, so all we need to do here is take another active reference to
> * the perag for the cached association.
> *
> - * If we fail to store the association, we need to drop the fstrms
> - * counter as well as drop the perag reference we take here for the
> - * item. We do not need to return an error for this failure - as long as
> - * we return a referenced AG, the allocation can still go ahead just
> - * fine.
> + * If we fail to store the association, we do not need to return an
> + * error for this failure - as long as we return a referenced AG, the
> + * allocation can still go ahead just fine.
> */
> item = kmalloc(sizeof(*item), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
> if (!item)
> @@ -316,14 +314,9 @@ xfs_filestream_create_association(
>
> atomic_inc(&pag_group(args->pag)->xg_active_ref);
> item->pag = args->pag;
> - error = xfs_mru_cache_insert(mp->m_filestream, pino, &item->mru);
> - if (error)
> - goto out_free_item;
> + xfs_mru_cache_insert(mp->m_filestream, pino, &item->mru);
Hmm, don't you still need to check for -ENOMEM returns? Or if truly
none of the callers care anymore, then can we get rid of the return
value for xfs_mru_cache_insert?
--D
> return 0;
>
> -out_free_item:
> - xfs_perag_rele(item->pag);
> - kfree(item);
> out_put_fstrms:
> atomic_dec(&args->pag->pagf_fstrms);
> return 0;
> diff --git a/fs/xfs/xfs_mru_cache.c b/fs/xfs/xfs_mru_cache.c
> index d0f5b403bdbe..08443ceec329 100644
> --- a/fs/xfs/xfs_mru_cache.c
> +++ b/fs/xfs/xfs_mru_cache.c
> @@ -414,6 +414,8 @@ xfs_mru_cache_destroy(
> * To insert an element, call xfs_mru_cache_insert() with the data store, the
> * element's key and the client data pointer. This function returns 0 on
> * success or ENOMEM if memory for the data element couldn't be allocated.
> + *
> + * The passed in elem is freed through the per-cache free_func on failure.
> */
> int
> xfs_mru_cache_insert(
> @@ -421,14 +423,15 @@ xfs_mru_cache_insert(
> unsigned long key,
> struct xfs_mru_cache_elem *elem)
> {
> - int error;
> + int error = -EINVAL;
>
> ASSERT(mru && mru->lists);
> if (!mru || !mru->lists)
> - return -EINVAL;
> + goto out_free;
>
> + error = -ENOMEM;
> if (radix_tree_preload(GFP_KERNEL))
> - return -ENOMEM;
> + goto out_free;
>
> INIT_LIST_HEAD(&elem->list_node);
> elem->key = key;
> @@ -440,6 +443,12 @@ xfs_mru_cache_insert(
> _xfs_mru_cache_list_insert(mru, elem);
> spin_unlock(&mru->lock);
>
> + if (error)
> + goto out_free;
> + return 0;
> +
> +out_free:
> + mru->free_func(mru->data, elem);
> return error;
> }
>
> --
> 2.34.1
>
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