From f5fbe6b7ad6ef1fbdf8074a6ca9fdab739bf86d4 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Mon, 28 Jun 2021 19:35:59 -0700 Subject: writeback, cgroup: support switching multiple inodes at once Currently only a single inode can be switched to another writeback structure at once. That means to switch an inode a separate inode_switch_wbs_context structure must be allocated, and a separate rcu callback and work must be scheduled. It's fine for the existing ad-hoc switching, which is not happening that often, but sub-optimal for massive switching required in order to release a writeback structure. To prepare for it, let's add a support for switching multiple inodes at once. Instead of containing a single inode pointer, inode_switch_wbs_context will contain a NULL-terminated array of inode pointers. inode_do_switch_wbs() will be called for each inode. To optimize the locking bdi->wb_switch_rwsem, old_wb's and new_wb's list_locks will be acquired and released only once altogether for all inodes. wb_wakeup() will be also be called only once. Instead of calling wb_put(old_wb) after each successful switch, wb_put_many() is introduced and used. Link: https://lkml.kernel.org/r/20210608230225.2078447-8-guro@fb.com Signed-off-by: Roman Gushchin Acked-by: Tejun Heo Reviewed-by: Jan Kara Acked-by: Dennis Zhou Cc: Alexander Viro Cc: Dave Chinner Cc: Jan Kara Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/backing-dev-defs.h | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) (limited to 'include/linux/backing-dev-defs.h') diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index e5dc238ebe4f..63f52ad2ce7a 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -240,8 +240,9 @@ static inline void wb_get(struct bdi_writeback *wb) /** * wb_put - decrement a wb's refcount * @wb: bdi_writeback to put + * @nr: number of references to put */ -static inline void wb_put(struct bdi_writeback *wb) +static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr) { if (WARN_ON_ONCE(!wb->bdi)) { /* @@ -252,7 +253,16 @@ static inline void wb_put(struct bdi_writeback *wb) } if (wb != &wb->bdi->wb) - percpu_ref_put(&wb->refcnt); + percpu_ref_put_many(&wb->refcnt, nr); +} + +/** + * wb_put - decrement a wb's refcount + * @wb: bdi_writeback to put + */ +static inline void wb_put(struct bdi_writeback *wb) +{ + wb_put_many(wb, 1); } /** @@ -281,6 +291,10 @@ static inline void wb_put(struct bdi_writeback *wb) { } +static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr) +{ +} + static inline bool wb_dying(struct bdi_writeback *wb) { return false; -- cgit v1.2.3