| Message ID | 20211020144119.142582-5-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/4] blk-mq: only flush requests from the plug in blk_mq_submit_bio | expand |
On Wed, Oct 20, 2021 at 04:41:19PM +0200, Christoph Hellwig wrote: > Consolidate the various helpers into a single blk_flush_plug helper that > takes a plk_plug and the from_scheduler bool and switch all callsites to > call it directly. Checks that the plug is non-NULL must be performed by > the caller, something that most already do anyway. > > Signed-off-by: Christoph Hellwig <hch@lst.de> This patch as commit 008f75a20e70 ("block: cleanup the flush plug helpers") in -next causes the following errors with CONFIG_BLOCK=n (tinyconfig): kernel/sched/core.c: In function ‘sched_submit_work’: kernel/sched/core.c:6346:35: error: ‘struct task_struct’ has no member named ‘plug’ 6346 | blk_flush_plug(tsk->plug, true); | ^~ kernel/sched/core.c: In function ‘io_schedule_prepare’: kernel/sched/core.c:8357:20: error: ‘struct task_struct’ has no member named ‘plug’ 8357 | if (current->plug) | ^~ kernel/sched/core.c:8358:39: error: ‘struct task_struct’ has no member named ‘plug’ 8358 | blk_flush_plug(current->plug, true); | ^~ I tested the latest block tree and did not see it fixed nor did I see it reported or fixed elsewhere. Cheers, Nathan
On 10/22/21 2:09 PM, Nathan Chancellor wrote: > On Wed, Oct 20, 2021 at 04:41:19PM +0200, Christoph Hellwig wrote: >> Consolidate the various helpers into a single blk_flush_plug helper that >> takes a plk_plug and the from_scheduler bool and switch all callsites to >> call it directly. Checks that the plug is non-NULL must be performed by >> the caller, something that most already do anyway. >> >> Signed-off-by: Christoph Hellwig <hch@lst.de> > > This patch as commit 008f75a20e70 ("block: cleanup the flush plug > helpers") in -next causes the following errors with CONFIG_BLOCK=n > (tinyconfig): > > kernel/sched/core.c: In function ‘sched_submit_work’: > kernel/sched/core.c:6346:35: error: ‘struct task_struct’ has no member named ‘plug’ > 6346 | blk_flush_plug(tsk->plug, true); > | ^~ > kernel/sched/core.c: In function ‘io_schedule_prepare’: > kernel/sched/core.c:8357:20: error: ‘struct task_struct’ has no member named ‘plug’ > 8357 | if (current->plug) > | ^~ > kernel/sched/core.c:8358:39: error: ‘struct task_struct’ has no member named ‘plug’ > 8358 | blk_flush_plug(current->plug, true); > | ^~ > > I tested the latest block tree and did not see it fixed nor did I see it > reported or fixed elsewhere. This should fix it, thanks for reporting. commit 599593a82fc57f5e9453c8ef7420df3206934a0c Author: Jens Axboe <axboe@kernel.dk> Date: Fri Oct 22 19:35:45 2021 -0600 sched: make task_struct->plug always defined If CONFIG_BLOCK isn't set, then it's an empty struct anyway. Just make it generally available, so we don't break the compile: kernel/sched/core.c: In function ‘sched_submit_work’: kernel/sched/core.c:6346:35: error: ‘struct task_struct’ has no member named ‘plug’ 6346 | blk_flush_plug(tsk->plug, true); | ^~ kernel/sched/core.c: In function ‘io_schedule_prepare’: kernel/sched/core.c:8357:20: error: ‘struct task_struct’ has no member named ‘plug’ 8357 | if (current->plug) | ^~ kernel/sched/core.c:8358:39: error: ‘struct task_struct’ has no member named ‘plug’ 8358 | blk_flush_plug(current->plug, true); | ^~ Reported-by: Nathan Chancellor <nathan@kernel.org> Fixes: 008f75a20e70 ("block: cleanup the flush plug helpers") Signed-off-by: Jens Axboe <axboe@kernel.dk> diff --git a/include/linux/sched.h b/include/linux/sched.h index c1a927ddec64..e0454e60fe8f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1160,10 +1160,8 @@ struct task_struct { /* Stacked block device info: */ struct bio_list *bio_list; -#ifdef CONFIG_BLOCK /* Stack plugging: */ struct blk_plug *plug; -#endif /* VM state: */ struct reclaim_state *reclaim_state;
diff --git a/block/blk-core.c b/block/blk-core.c index 63fee1f82bd7d..bb25934c9408a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1089,7 +1089,7 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) return 0; if (current->plug) - blk_flush_plug_list(current->plug, false); + blk_flush_plug(current->plug, false); if (blk_queue_enter(q, BLK_MQ_REQ_NOWAIT)) return 0; @@ -1637,7 +1637,7 @@ struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, } EXPORT_SYMBOL(blk_check_plugged); -void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) +void blk_flush_plug(struct blk_plug *plug, bool from_schedule) { if (!list_empty(&plug->cb_list)) flush_plug_callbacks(plug, from_schedule); @@ -1659,11 +1659,10 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) */ void blk_finish_plug(struct blk_plug *plug) { - if (plug != current->plug) - return; - blk_flush_plug_list(plug, false); - - current->plug = NULL; + if (plug == current->plug) { + blk_flush_plug(plug, false); + current->plug = NULL; + } } EXPORT_SYMBOL(blk_finish_plug); diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 81ec192ce0673..4124a89a1a5df 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1893,7 +1893,8 @@ static long writeback_sb_inodes(struct super_block *sb, * unplug, so get our IOs out the door before we * give up the CPU. */ - blk_flush_plug(current); + if (current->plug) + blk_flush_plug(current->plug, false); cond_resched(); } @@ -2291,7 +2292,7 @@ void wakeup_flusher_threads(enum wb_reason reason) * If we are expecting writeback progress we must submit plugged IO. */ if (blk_needs_flush_plug(current)) - blk_schedule_flush_plug(current); + blk_flush_plug(current->plug, true); rcu_read_lock(); list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index c95aee920bbb4..16647fbd1c2c4 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -708,9 +708,8 @@ extern void blk_set_queue_dying(struct request_queue *); * as the lock contention for request_queue lock is reduced. * * It is ok not to disable preemption when adding the request to the plug list - * or when attempting a merge, because blk_schedule_flush_list() will only flush - * the plug list when the task sleeps by itself. For details, please see - * schedule() where blk_schedule_flush_plug() is called. + * or when attempting a merge. For details, please see schedule() where + * blk_flush_plug() is called. */ struct blk_plug { struct request *mq_list; /* blk-mq requests */ @@ -740,23 +739,8 @@ extern struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, extern void blk_start_plug(struct blk_plug *); extern void blk_start_plug_nr_ios(struct blk_plug *, unsigned short); extern void blk_finish_plug(struct blk_plug *); -extern void blk_flush_plug_list(struct blk_plug *, bool); -static inline void blk_flush_plug(struct task_struct *tsk) -{ - struct blk_plug *plug = tsk->plug; - - if (plug) - blk_flush_plug_list(plug, false); -} - -static inline void blk_schedule_flush_plug(struct task_struct *tsk) -{ - struct blk_plug *plug = tsk->plug; - - if (plug) - blk_flush_plug_list(plug, true); -} +void blk_flush_plug(struct blk_plug *plug, bool from_schedule); static inline bool blk_needs_flush_plug(struct task_struct *tsk) { @@ -785,15 +769,10 @@ static inline void blk_finish_plug(struct blk_plug *plug) { } -static inline void blk_flush_plug(struct task_struct *task) -{ -} - -static inline void blk_schedule_flush_plug(struct task_struct *task) +static inline void blk_flush_plug(struct blk_plug *plug, bool async) { } - static inline bool blk_needs_flush_plug(struct task_struct *tsk) { return false; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 92ef7b68198c4..34f37502c27e1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6343,7 +6343,7 @@ static inline void sched_submit_work(struct task_struct *tsk) * make sure to submit it to avoid deadlocks. */ if (blk_needs_flush_plug(tsk)) - blk_schedule_flush_plug(tsk); + blk_flush_plug(tsk->plug, true); } static void sched_update_worker(struct task_struct *tsk) @@ -8354,7 +8354,8 @@ int io_schedule_prepare(void) int old_iowait = current->in_iowait; current->in_iowait = 1; - blk_schedule_flush_plug(current); + if (current->plug) + blk_flush_plug(current->plug, true); return old_iowait; }
Consolidate the various helpers into a single blk_flush_plug helper that takes a plk_plug and the from_scheduler bool and switch all callsites to call it directly. Checks that the plug is non-NULL must be performed by the caller, something that most already do anyway. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/blk-core.c | 13 ++++++------- fs/fs-writeback.c | 5 +++-- include/linux/blkdev.h | 29 ++++------------------------- kernel/sched/core.c | 5 +++-- 4 files changed, 16 insertions(+), 36 deletions(-)