[PATCH v6 34/45] xfs: dynamically allocate the xfs-buf shrinker

Qi Zheng
2023-09-11T22:45:40Z

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the xfs-buf shrinker, so that it can be freed
asynchronously via 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>
CC: Chandan Babu R <chandan.babu@oracle.com>
CC: "Darrick J. Wong" <djwong@kernel.org>
CC: linux-xfs@vger.kernel.org
---
fs/xfs/xfs_buf.c | 24 +++++++++++++-----------
fs/xfs/xfs_buf.h | 2 +-
2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index c1ece4a08ff4..9e7ba04572db 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1913,8 +1913,7 @@ 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;

@@ -1936,8 +1935,7 @@ 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);
}

@@ -1947,7 +1945,7 @@ xfs_free_buftarg(
{
struct block_device *bdev = btp->bt_bdev;

- 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);
@@ -2031,13 +2029,17 @@ 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->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 df8f47953bb4..702e7d9ea2ac 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -108,7 +108,7 @@ 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