xfs: dynamically allocate the xfs-inodegc shrinker

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the xfs-inodegc 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_mount.

Link: https://lkml.kernel.org/r/20230911094444.68966-36-zhengqi.arch@bytedance.com
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: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Carlos Llamas <cmllamas@google.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Chuck Lever <cel@kernel.org>
Cc: Coly Li <colyli@suse.de>
Cc: Dai Ngo <Dai.Ngo@oracle.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Airlie <airlied@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Gao Xiang <hsiangkao@linux.alibaba.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jeffle Xu <jefflexu@linux.alibaba.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Kirill Tkhai <tkhai@ya.ru>
Cc: Marijn Suijten <marijn.suijten@somainline.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Olga Kornievskaia <kolga@netapp.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sean Paul <sean@poorly.run>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Song Liu <song@kernel.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/xfs/xfs_icache.c

@@ -2165,8 +2165,7 @@ xfs_inodegc_shrinker_count(
 	struct shrinker		*shrink,
 	struct shrink_control	*sc)
 {
-	struct xfs_mount	*mp = container_of(shrink, struct xfs_mount,
-						   m_inodegc_shrinker);
+	struct xfs_mount	*mp = shrink->private_data;
 	struct xfs_inodegc	*gc;
 	int			cpu;
 
@@ -2187,8 +2186,7 @@ xfs_inodegc_shrinker_scan(
 	struct shrinker		*shrink,
 	struct shrink_control	*sc)
 {
-	struct xfs_mount	*mp = container_of(shrink, struct xfs_mount,
-						   m_inodegc_shrinker);
+	struct xfs_mount	*mp = shrink->private_data;
 	struct xfs_inodegc	*gc;
 	int			cpu;
 	bool			no_items = true;
@@ -2224,13 +2222,19 @@ int
 xfs_inodegc_register_shrinker(
 	struct xfs_mount	*mp)
 {
-	struct shrinker		*shrink = &mp->m_inodegc_shrinker;
+	mp->m_inodegc_shrinker = shrinker_alloc(SHRINKER_NONSLAB,
+						"xfs-inodegc:%s",
+						mp->m_super->s_id);
+	if (!mp->m_inodegc_shrinker)
+		return -ENOMEM;
 
-	shrink->count_objects = xfs_inodegc_shrinker_count;
-	shrink->scan_objects = xfs_inodegc_shrinker_scan;
-	shrink->seeks = 0;
-	shrink->flags = SHRINKER_NONSLAB;
-	shrink->batch = XFS_INODEGC_SHRINKER_BATCH;
+	mp->m_inodegc_shrinker->count_objects = xfs_inodegc_shrinker_count;
+	mp->m_inodegc_shrinker->scan_objects = xfs_inodegc_shrinker_scan;
+	mp->m_inodegc_shrinker->seeks = 0;
+	mp->m_inodegc_shrinker->batch = XFS_INODEGC_SHRINKER_BATCH;
+	mp->m_inodegc_shrinker->private_data = mp;
 
-	return register_shrinker(shrink, "xfs-inodegc:%s", mp->m_super->s_id);
+	shrinker_register(mp->m_inodegc_shrinker);
+
+	return 0;
 }

fs/xfs/xfs_mount.c

@@ -1021,7 +1021,7 @@ xfs_mountfs(
  out_log_dealloc:
 	xfs_log_mount_cancel(mp);
  out_inodegc_shrinker:
-	unregister_shrinker(&mp->m_inodegc_shrinker);
+	shrinker_free(mp->m_inodegc_shrinker);
  out_fail_wait:
 	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
 		xfs_buftarg_drain(mp->m_logdev_targp);
@@ -1104,7 +1104,7 @@ xfs_unmountfs(
 #if defined(DEBUG)
 	xfs_errortag_clearall(mp);
 #endif
-	unregister_shrinker(&mp->m_inodegc_shrinker);
+	shrinker_free(mp->m_inodegc_shrinker);
 	xfs_free_perag(mp);
 
 	xfs_errortag_del(mp);

fs/xfs/xfs_mount.h

@@ -219,7 +219,7 @@ typedef struct xfs_mount {
 	atomic_t		m_agirotor;	/* last ag dir inode alloced */
 
 	/* Memory shrinker to throttle and reprioritize inodegc */
-	struct shrinker		m_inodegc_shrinker;
+	struct shrinker		*m_inodegc_shrinker;
 	/*
 	 * Workqueue item so that we can coalesce multiple inode flush attempts
 	 * into a single flush.