Previous patches made all the data, which is touched from super_cache_count(), destroyed from destroy_super_work(): s_dentry_lru, s_inode_lru and super_block::s_fs_info.
super_cache_scan() can't be called after SB_ACTIVE is cleared in generic_shutdown_super(). So, it safe to move heavy unregister_shrinker_delayed_finalize() part to delayed work, i.e. it's safe for parallel do_shrink_slab() to be executed between unregister_shrinker_delayed_initiate() and destroy_super_work()->unregister_shrinker_delayed_finalize(). This makes the heavy synchronize_srcu() to do not affect on user-visible unregistration speed (since now it's executed from workqueue). All further time-critical for unregistration places may be written in the same conception. Signed-off-by: Kirill Tkhai <[email protected]> --- fs/super.c | 4 +++- include/linux/fs.h | 5 +++++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/super.c b/fs/super.c index c60f092538c7..33e829741ec0 100644 --- a/fs/super.c +++ b/fs/super.c @@ -165,6 +165,8 @@ static void destroy_super_work(struct work_struct *work) destroy_work); int i; + unregister_shrinker_delayed_finalize(&s->s_shrink); + WARN_ON(list_lru_count(&s->s_dentry_lru)); WARN_ON(list_lru_count(&s->s_inode_lru)); list_lru_destroy(&s->s_dentry_lru); @@ -334,7 +336,7 @@ void deactivate_locked_super(struct super_block *s) struct file_system_type *fs = s->s_type; if (atomic_dec_and_test(&s->s_active)) { cleancache_invalidate_fs(s); - unregister_shrinker(&s->s_shrink); + unregister_shrinker_delayed_initiate(&s->s_shrink); fs->kill_sb(s); put_filesystem(fs); diff --git a/include/linux/fs.h b/include/linux/fs.h index 33dfaed0a01a..8a1cd3097eef 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1902,6 +1902,11 @@ struct super_operations { struct dquot **(*get_dquots)(struct inode *); #endif int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t); + /* + * Shrinker may call these two function on destructing super_block + * till unregister_shrinker_delayed_finalize() has completed + * in destroy_super_work(), and they must care about that. + */ long (*nr_cached_objects)(struct super_block *, struct shrink_control *); long (*free_cached_objects)(struct super_block *,
