[PATCH v4 37/48] xfs: dynamically allocate the xfs-buf shrinker

Qi Zheng
2023-08-07T11:27:02Z

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the xfs-buf shrinker, so that it can be freed
asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
read-side critical section when releasing the struct xfs_buftarg.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
---
fs/xfs/xfs_buf.c | 25 ++++++++++++++-----------
fs/xfs/xfs_buf.h | 2 +-
2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 15d1e5a7c2d3..715730fc91cb 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1906,8 +1906,7 @@ xfs_buftarg_shrink_scan(
struct shrinker *shrink,
struct shrink_control *sc)
{
- struct xfs_buftarg *btp = container_of(shrink,
- struct xfs_buftarg, bt_shrinker);
+ struct xfs_buftarg *btp = shrink->private_data;
LIST_HEAD(dispose);
unsigned long freed;

@@ -1929,8 +1928,7 @@ xfs_buftarg_shrink_count(
struct shrinker *shrink,
struct shrink_control *sc)
{
- struct xfs_buftarg *btp = container_of(shrink,
- struct xfs_buftarg, bt_shrinker);
+ struct xfs_buftarg *btp = shrink->private_data;
return list_lru_shrink_count(&btp->bt_lru, sc);
}

@@ -1938,7 +1936,7 @@ void
xfs_free_buftarg(
struct xfs_buftarg *btp)
{
- unregister_shrinker(&btp->bt_shrinker);
+ shrinker_free(btp->bt_shrinker);
ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
percpu_counter_destroy(&btp->bt_io_count);
list_lru_destroy(&btp->bt_lru);
@@ -2021,13 +2019,18 @@ xfs_alloc_buftarg(
if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
goto error_lru;

- btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
- btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
- btp->bt_shrinker.seeks = DEFAULT_SEEKS;
- btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
- if (register_shrinker(&btp->bt_shrinker, "xfs-buf:%s",
- mp->m_super->s_id))
+ btp->bt_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-buf:%s",
+ mp->m_super->s_id);
+ if (!btp->bt_shrinker)
goto error_pcpu;
+
+ btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;
+ btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
+ btp->bt_shrinker->seeks = DEFAULT_SEEKS;
+ btp->bt_shrinker->private_data = btp;
+
+ shrinker_register(btp->bt_shrinker);
+
return btp;

error_pcpu:
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 549c60942208..4e6969a675f7 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -102,7 +102,7 @@ typedef struct xfs_buftarg {
size_t bt_logical_sectormask;

/* LRU control structures */
- struct shrinker bt_shrinker;
+ struct shrinker *bt_shrinker;
struct list_lru bt_lru;

struct percpu_counter bt_io_count;
--
2.30.2