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SubjectRe: [PATCH v4 1/3] btrfs: add might_sleep() to some places in update_qgroup_limit_item()
On Wed, Nov 16, 2022 at 01:17:07AM +0800, ChenXiaoSong wrote:
> As the potential sleeping under spin lock is hard to spot, we should add
> might_sleep() to some places.
>
> Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
> ---
> fs/btrfs/ctree.c | 2 ++
> fs/btrfs/qgroup.c | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index a9543f01184c..809053e9cfde 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -1934,6 +1934,8 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> int min_write_lock_level;
> int prev_cmp;
>
> + might_sleep();

This needs some explanation in the changelog, the reason was mentioned
in some past patch iteration that it's due to potential IO fi the blocks
are not cached.

> +
> lowest_level = p->lowest_level;
> WARN_ON(lowest_level && ins_len > 0);
> WARN_ON(p->nodes[0] != NULL);
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index 9334c3157c22..d0480b9c6c86 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -779,6 +779,8 @@ static int update_qgroup_limit_item(struct btrfs_trans_handle *trans,
> int ret;
> int slot;
>
> + might_sleep();

This one is redundant, no? There's call to btrfs_search_slot a few lines
below.

> +
> key.objectid = 0;
> key.type = BTRFS_QGROUP_LIMIT_KEY;
> key.offset = qgroup->qgroupid;
> --
> 2.31.1
>

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