| Message ID | 20170925202924.16603-8-bart.vanassche@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Sep 25, 2017 at 01:29:24PM -0700, Bart Van Assche wrote: > It is essential during suspend and resume that neither the filesystem > state nor the filesystem metadata in RAM changes. This is why while > the hibernation image is being written or restored that SCSI devices > are quiesced. The SCSI core quiesces devices through scsi_device_quiesce() > and scsi_device_resume(). In the SDEV_QUIESCE state execution of > non-preempt requests is deferred. This is realized by returning > BLKPREP_DEFER from inside scsi_prep_state_check() for quiesced SCSI > devices. Avoid that a full queue prevents power management requests > to be submitted by deferring allocation of non-preempt requests for > devices in the quiesced state. This patch has been tested by running > the following commands and by verifying that after resume the fio job > is still running: > > for d in /sys/class/block/sd*[a-z]; do > hcil=$(readlink "$d/device") > hcil=${hcil#../../../} > echo 4 > "$d/queue/nr_requests" > echo 1 > "/sys/class/scsi_device/$hcil/device/queue_depth" > done > bdev=$(readlink /dev/disk/by-uuid/5217d83f-213e-4b42-b86e-20013325ba6c) > bdev=${bdev#../../} > hcil=$(readlink "/sys/block/$bdev/device") > hcil=${hcil#../../../} > fio --name="$bdev" --filename="/dev/$bdev" --buffered=0 --bs=512 --rw=randread \ > --ioengine=libaio --numjobs=4 --iodepth=16 --iodepth_batch=1 --thread \ > --loops=$((2**31)) & > pid=$! > sleep 1 > systemctl hibernate > sleep 10 > kill $pid > > Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> > References: "I/O hangs after resuming from suspend-to-ram" (https://marc.info/?l=linux-block&m=150340235201348). > Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> > Cc: Martin K. Petersen <martin.petersen@oracle.com> > Cc: Ming Lei <ming.lei@redhat.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Hannes Reinecke <hare@suse.com> > Cc: Johannes Thumshirn <jthumshirn@suse.de> > --- > block/blk-core.c | 41 +++++++++++++++++++++++++++++++---------- > block/blk-mq.c | 4 ++-- > block/blk-timeout.c | 2 +- > fs/block_dev.c | 4 ++-- > include/linux/blkdev.h | 2 +- > 5 files changed, 37 insertions(+), 16 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index 9111a8f9c7a1..01b7afee58f0 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -351,10 +351,12 @@ void blk_set_preempt_only(struct request_queue *q, bool preempt_only) > unsigned long flags; > > spin_lock_irqsave(q->queue_lock, flags); > - if (preempt_only) > + if (preempt_only) { > queue_flag_set(QUEUE_FLAG_PREEMPT_ONLY, q); > - else > + } else { > queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q); > + wake_up_all(&q->mq_freeze_wq); > + } > spin_unlock_irqrestore(q->queue_lock, flags); > } > EXPORT_SYMBOL(blk_set_preempt_only); > @@ -776,13 +778,31 @@ struct request_queue *blk_alloc_queue(gfp_t gfp_mask) > } > EXPORT_SYMBOL(blk_alloc_queue); > > -int blk_queue_enter(struct request_queue *q, bool nowait) > +/** > + * blk_queue_enter() - try to increase q->q_usage_counter > + * @q: request queue pointer > + * @nowait: if the queue is frozen, do not wait until it is unfrozen > + * @preempt: if QUEUE_FLAG_PREEMPT_ONLY has been set, do not wait until that > + * flag has been cleared > + */ > +int blk_queue_enter(struct request_queue *q, bool nowait, bool preempt) > { > while (true) { > int ret; > > - if (percpu_ref_tryget_live(&q->q_usage_counter)) > - return 0; > + if (percpu_ref_tryget_live(&q->q_usage_counter)) { > + /* > + * Since setting the PREEMPT_ONLY flag is followed > + * by a switch of q_usage_counter from per-cpu to > + * atomic mode and back to per-cpu and since the > + * switch to atomic mode uses call_rcu_sched(), it > + * is not necessary to call smp_rmb() here. > + */ rcu_read_lock is held only inside percpu_ref_tryget_live(). Without one explicit barrier(smp_mb) between getting the refcounter and reading the preempt only flag, the two operations(writing to refcounter and reading the flag) can be reordered, so unfreeze/unfreeze may be completed before this IO is completed. > + if (preempt || !blk_queue_preempt_only(q)) > + return 0; > + else > + percpu_ref_put(&q->q_usage_counter); > + } > > if (nowait) > return -EBUSY; > @@ -797,7 +817,8 @@ int blk_queue_enter(struct request_queue *q, bool nowait) > smp_rmb(); > > ret = wait_event_interruptible(q->mq_freeze_wq, > - !atomic_read(&q->mq_freeze_depth) || > + (atomic_read(&q->mq_freeze_depth) == 0 && > + (preempt || !blk_queue_preempt_only(q))) || > blk_queue_dying(q)); > if (blk_queue_dying(q)) > return -ENODEV; > @@ -1416,7 +1437,7 @@ static struct request *blk_old_get_request(struct request_queue *q, > create_io_context(gfp_mask, q->node); > > ret = blk_queue_enter(q, !(gfp_mask & __GFP_DIRECT_RECLAIM) || > - (op & REQ_NOWAIT)); > + (op & REQ_NOWAIT), op & REQ_PREEMPT); > if (ret) > return ERR_PTR(ret); > spin_lock_irq(q->queue_lock); > @@ -2184,6 +2205,7 @@ blk_qc_t generic_make_request(struct bio *bio) > */ > struct bio_list bio_list_on_stack[2]; > blk_qc_t ret = BLK_QC_T_NONE; > + const bool nowait = bio->bi_opf & REQ_NOWAIT; > > if (!generic_make_request_checks(bio)) > goto out; > @@ -2223,7 +2245,7 @@ blk_qc_t generic_make_request(struct bio *bio) > do { > struct request_queue *q = bio->bi_disk->queue; > > - if (likely(blk_queue_enter(q, bio->bi_opf & REQ_NOWAIT) == 0)) { > + if (likely(blk_queue_enter(q, nowait, false) == 0)) { > struct bio_list lower, same; > > /* Create a fresh bio_list for all subordinate requests */ > @@ -2248,8 +2270,7 @@ blk_qc_t generic_make_request(struct bio *bio) > bio_list_merge(&bio_list_on_stack[0], &same); > bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); > } else { > - if (unlikely(!blk_queue_dying(q) && > - (bio->bi_opf & REQ_NOWAIT))) > + if (unlikely(!blk_queue_dying(q) && nowait)) > bio_wouldblock_error(bio); > else > bio_io_error(bio); > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 10c1f49f663d..cbf7bf7e3d13 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -384,7 +384,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, > struct request *rq; > int ret; > > - ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT); > + ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT, op & REQ_PREEMPT); > if (ret) > return ERR_PTR(ret); > > @@ -423,7 +423,7 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, > if (hctx_idx >= q->nr_hw_queues) > return ERR_PTR(-EIO); > > - ret = blk_queue_enter(q, true); > + ret = blk_queue_enter(q, true, op & REQ_PREEMPT); > if (ret) > return ERR_PTR(ret); > > diff --git a/block/blk-timeout.c b/block/blk-timeout.c > index 17ec83bb0900..0dfdc975473a 100644 > --- a/block/blk-timeout.c > +++ b/block/blk-timeout.c > @@ -134,7 +134,7 @@ void blk_timeout_work(struct work_struct *work) > struct request *rq, *tmp; > int next_set = 0; > > - if (blk_queue_enter(q, true)) > + if (blk_queue_enter(q, true, true)) > return; > spin_lock_irqsave(q->queue_lock, flags); > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 93d088ffc05c..e9ca45087a40 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -674,7 +674,7 @@ int bdev_read_page(struct block_device *bdev, sector_t sector, > if (!ops->rw_page || bdev_get_integrity(bdev)) > return result; > > - result = blk_queue_enter(bdev->bd_queue, false); > + result = blk_queue_enter(bdev->bd_queue, false, false); > if (result) > return result; > result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, false); > @@ -710,7 +710,7 @@ int bdev_write_page(struct block_device *bdev, sector_t sector, > > if (!ops->rw_page || bdev_get_integrity(bdev)) > return -EOPNOTSUPP; > - result = blk_queue_enter(bdev->bd_queue, false); > + result = blk_queue_enter(bdev->bd_queue, false, false); > if (result) > return result; > > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index 5bd87599eed0..a025597c378a 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -964,7 +964,7 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t, > extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t, > struct scsi_ioctl_command __user *); > > -extern int blk_queue_enter(struct request_queue *q, bool nowait); > +extern int blk_queue_enter(struct request_queue *q, bool nowait, bool preempt); > extern void blk_queue_exit(struct request_queue *q); > extern void blk_start_queue(struct request_queue *q); > extern void blk_start_queue_async(struct request_queue *q); > -- > 2.14.1 >
On Tue, 2017-09-26 at 06:59 +0800, Ming Lei wrote: > On Mon, Sep 25, 2017 at 01:29:24PM -0700, Bart Van Assche wrote: > > +int blk_queue_enter(struct request_queue *q, bool nowait, bool preempt) > > { > > while (true) { > > int ret; > > > > - if (percpu_ref_tryget_live(&q->q_usage_counter)) > > - return 0; > > + if (percpu_ref_tryget_live(&q->q_usage_counter)) { > > + /* > > + * Since setting the PREEMPT_ONLY flag is followed > > + * by a switch of q_usage_counter from per-cpu to > > + * atomic mode and back to per-cpu and since the > > + * switch to atomic mode uses call_rcu_sched(), it > > + * is not necessary to call smp_rmb() here. > > + */ > > rcu_read_lock is held only inside percpu_ref_tryget_live(). > > Without one explicit barrier(smp_mb) between getting the refcounter > and reading the preempt only flag, the two operations(writing to > refcounter and reading the flag) can be reordered, so > unfreeze/unfreeze may be completed before this IO is completed. Sorry but I disagree. I'm using RCU to achieve the same effect as a barrier and to move the cost of the barrier from the reader to the updater. See also Paul E. McKenney, Mathieu Desnoyers, Lai Jiangshan, and Josh Triplett, The RCU-barrier menagerie, LWN.net, November 12, 2013 (https://lwn.net/Articles/573497/). Bart.
On Mon, Sep 25, 2017 at 11:13:47PM +0000, Bart Van Assche wrote: > On Tue, 2017-09-26 at 06:59 +0800, Ming Lei wrote: > > On Mon, Sep 25, 2017 at 01:29:24PM -0700, Bart Van Assche wrote: > > > +int blk_queue_enter(struct request_queue *q, bool nowait, bool preempt) > > > { > > > while (true) { > > > int ret; > > > > > > - if (percpu_ref_tryget_live(&q->q_usage_counter)) > > > - return 0; > > > + if (percpu_ref_tryget_live(&q->q_usage_counter)) { > > > + /* > > > + * Since setting the PREEMPT_ONLY flag is followed > > > + * by a switch of q_usage_counter from per-cpu to > > > + * atomic mode and back to per-cpu and since the > > > + * switch to atomic mode uses call_rcu_sched(), it > > > + * is not necessary to call smp_rmb() here. > > > + */ > > > > rcu_read_lock is held only inside percpu_ref_tryget_live(). > > > > Without one explicit barrier(smp_mb) between getting the refcounter > > and reading the preempt only flag, the two operations(writing to > > refcounter and reading the flag) can be reordered, so > > unfreeze/unfreeze may be completed before this IO is completed. > > Sorry but I disagree. I'm using RCU to achieve the same effect as a barrier > and to move the cost of the barrier from the reader to the updater. See also > Paul E. McKenney, Mathieu Desnoyers, Lai Jiangshan, and Josh Triplett, > The RCU-barrier menagerie, LWN.net, November 12, 2013 > (https://lwn.net/Articles/573497/). Let me explain it in a bit details: 1) in SCSI quiesce path: We can think there is one synchronize_rcu() in freeze/unfreeze. Let's see the RCU document: Documentation/RCU/whatisRCU.txt: void synchronize_rcu(void); Marks the end of updater code and the beginning of reclaimer code. It does this by blocking until all pre-existing RCU read-side critical sections on all CPUs have completed. Note that synchronize_rcu() will -not- necessarily wait for any subsequent RCU read-side critical sections to complete. For example, consider the following sequence of events: So synchronize_rcu() in SCSI quiesce path just waits for completion of pre-existing read-side critical section, and subsequent RCU read-side critical sections won't be waited. 2) in normal I/O path of blk_enter_queue() - only rcu read lock is held in percpu_ref_tryget_live(), and the lock is released when this helper returns. - there isn't explicit barrier(smp_mb()) between percpu_ref_tryget_live() and checking flag of preempt only, so writing to percpu_ref counter and reading the preempt flag can be reordered as the following: -- check flag of preempt only current process preempt out now, and just at the exact time, SCSI quiesce is run from another process, then freeze/unfreeze is completed because no pre-exit read-side critical sections, and the percpu_ref isn't held too. finally this process is preeempt in, and try to grab one ref and submit I/O after SCSI is quiesced(which shouldn't be allowed) -- percpu_ref_tryget_live()
On Tue, 2017-09-26 at 16:32 +0800, Ming Lei wrote: > On Mon, Sep 25, 2017 at 11:13:47PM +0000, Bart Van Assche wrote: > > Sorry but I disagree. I'm using RCU to achieve the same effect as a barrier > > and to move the cost of the barrier from the reader to the updater. See also > > Paul E. McKenney, Mathieu Desnoyers, Lai Jiangshan, and Josh Triplett, > > The RCU-barrier menagerie, LWN.net, November 12, 2013 > > (https://lwn.net/Articles/573497/). > > Let me explain it in a bit details: [ ... ] The approach I used in patch 7/7 is identical to one of the approaches explained in the article I referred to. If you do not agree that that approach is safe that means that you do not neither agree with Paul McKenney's view on how RCU works. Do you really think that you know more about RCU than Paul McKenney? Bart.
diff --git a/block/blk-core.c b/block/blk-core.c index 9111a8f9c7a1..01b7afee58f0 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -351,10 +351,12 @@ void blk_set_preempt_only(struct request_queue *q, bool preempt_only) unsigned long flags; spin_lock_irqsave(q->queue_lock, flags); - if (preempt_only) + if (preempt_only) { queue_flag_set(QUEUE_FLAG_PREEMPT_ONLY, q); - else + } else { queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q); + wake_up_all(&q->mq_freeze_wq); + } spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(blk_set_preempt_only); @@ -776,13 +778,31 @@ struct request_queue *blk_alloc_queue(gfp_t gfp_mask) } EXPORT_SYMBOL(blk_alloc_queue); -int blk_queue_enter(struct request_queue *q, bool nowait) +/** + * blk_queue_enter() - try to increase q->q_usage_counter + * @q: request queue pointer + * @nowait: if the queue is frozen, do not wait until it is unfrozen + * @preempt: if QUEUE_FLAG_PREEMPT_ONLY has been set, do not wait until that + * flag has been cleared + */ +int blk_queue_enter(struct request_queue *q, bool nowait, bool preempt) { while (true) { int ret; - if (percpu_ref_tryget_live(&q->q_usage_counter)) - return 0; + if (percpu_ref_tryget_live(&q->q_usage_counter)) { + /* + * Since setting the PREEMPT_ONLY flag is followed + * by a switch of q_usage_counter from per-cpu to + * atomic mode and back to per-cpu and since the + * switch to atomic mode uses call_rcu_sched(), it + * is not necessary to call smp_rmb() here. + */ + if (preempt || !blk_queue_preempt_only(q)) + return 0; + else + percpu_ref_put(&q->q_usage_counter); + } if (nowait) return -EBUSY; @@ -797,7 +817,8 @@ int blk_queue_enter(struct request_queue *q, bool nowait) smp_rmb(); ret = wait_event_interruptible(q->mq_freeze_wq, - !atomic_read(&q->mq_freeze_depth) || + (atomic_read(&q->mq_freeze_depth) == 0 && + (preempt || !blk_queue_preempt_only(q))) || blk_queue_dying(q)); if (blk_queue_dying(q)) return -ENODEV; @@ -1416,7 +1437,7 @@ static struct request *blk_old_get_request(struct request_queue *q, create_io_context(gfp_mask, q->node); ret = blk_queue_enter(q, !(gfp_mask & __GFP_DIRECT_RECLAIM) || - (op & REQ_NOWAIT)); + (op & REQ_NOWAIT), op & REQ_PREEMPT); if (ret) return ERR_PTR(ret); spin_lock_irq(q->queue_lock); @@ -2184,6 +2205,7 @@ blk_qc_t generic_make_request(struct bio *bio) */ struct bio_list bio_list_on_stack[2]; blk_qc_t ret = BLK_QC_T_NONE; + const bool nowait = bio->bi_opf & REQ_NOWAIT; if (!generic_make_request_checks(bio)) goto out; @@ -2223,7 +2245,7 @@ blk_qc_t generic_make_request(struct bio *bio) do { struct request_queue *q = bio->bi_disk->queue; - if (likely(blk_queue_enter(q, bio->bi_opf & REQ_NOWAIT) == 0)) { + if (likely(blk_queue_enter(q, nowait, false) == 0)) { struct bio_list lower, same; /* Create a fresh bio_list for all subordinate requests */ @@ -2248,8 +2270,7 @@ blk_qc_t generic_make_request(struct bio *bio) bio_list_merge(&bio_list_on_stack[0], &same); bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); } else { - if (unlikely(!blk_queue_dying(q) && - (bio->bi_opf & REQ_NOWAIT))) + if (unlikely(!blk_queue_dying(q) && nowait)) bio_wouldblock_error(bio); else bio_io_error(bio); diff --git a/block/blk-mq.c b/block/blk-mq.c index 10c1f49f663d..cbf7bf7e3d13 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -384,7 +384,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, struct request *rq; int ret; - ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT); + ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT, op & REQ_PREEMPT); if (ret) return ERR_PTR(ret); @@ -423,7 +423,7 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, if (hctx_idx >= q->nr_hw_queues) return ERR_PTR(-EIO); - ret = blk_queue_enter(q, true); + ret = blk_queue_enter(q, true, op & REQ_PREEMPT); if (ret) return ERR_PTR(ret); diff --git a/block/blk-timeout.c b/block/blk-timeout.c index 17ec83bb0900..0dfdc975473a 100644 --- a/block/blk-timeout.c +++ b/block/blk-timeout.c @@ -134,7 +134,7 @@ void blk_timeout_work(struct work_struct *work) struct request *rq, *tmp; int next_set = 0; - if (blk_queue_enter(q, true)) + if (blk_queue_enter(q, true, true)) return; spin_lock_irqsave(q->queue_lock, flags); diff --git a/fs/block_dev.c b/fs/block_dev.c index 93d088ffc05c..e9ca45087a40 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -674,7 +674,7 @@ int bdev_read_page(struct block_device *bdev, sector_t sector, if (!ops->rw_page || bdev_get_integrity(bdev)) return result; - result = blk_queue_enter(bdev->bd_queue, false); + result = blk_queue_enter(bdev->bd_queue, false, false); if (result) return result; result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, false); @@ -710,7 +710,7 @@ int bdev_write_page(struct block_device *bdev, sector_t sector, if (!ops->rw_page || bdev_get_integrity(bdev)) return -EOPNOTSUPP; - result = blk_queue_enter(bdev->bd_queue, false); + result = blk_queue_enter(bdev->bd_queue, false, false); if (result) return result; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 5bd87599eed0..a025597c378a 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -964,7 +964,7 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t, extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t, struct scsi_ioctl_command __user *); -extern int blk_queue_enter(struct request_queue *q, bool nowait); +extern int blk_queue_enter(struct request_queue *q, bool nowait, bool preempt); extern void blk_queue_exit(struct request_queue *q); extern void blk_start_queue(struct request_queue *q); extern void blk_start_queue_async(struct request_queue *q);
It is essential during suspend and resume that neither the filesystem state nor the filesystem metadata in RAM changes. This is why while the hibernation image is being written or restored that SCSI devices are quiesced. The SCSI core quiesces devices through scsi_device_quiesce() and scsi_device_resume(). In the SDEV_QUIESCE state execution of non-preempt requests is deferred. This is realized by returning BLKPREP_DEFER from inside scsi_prep_state_check() for quiesced SCSI devices. Avoid that a full queue prevents power management requests to be submitted by deferring allocation of non-preempt requests for devices in the quiesced state. This patch has been tested by running the following commands and by verifying that after resume the fio job is still running: for d in /sys/class/block/sd*[a-z]; do hcil=$(readlink "$d/device") hcil=${hcil#../../../} echo 4 > "$d/queue/nr_requests" echo 1 > "/sys/class/scsi_device/$hcil/device/queue_depth" done bdev=$(readlink /dev/disk/by-uuid/5217d83f-213e-4b42-b86e-20013325ba6c) bdev=${bdev#../../} hcil=$(readlink "/sys/block/$bdev/device") hcil=${hcil#../../../} fio --name="$bdev" --filename="/dev/$bdev" --buffered=0 --bs=512 --rw=randread \ --ioengine=libaio --numjobs=4 --iodepth=16 --iodepth_batch=1 --thread \ --loops=$((2**31)) & pid=$! sleep 1 systemctl hibernate sleep 10 kill $pid Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> References: "I/O hangs after resuming from suspend-to-ram" (https://marc.info/?l=linux-block&m=150340235201348). Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Ming Lei <ming.lei@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> --- block/blk-core.c | 41 +++++++++++++++++++++++++++++++---------- block/blk-mq.c | 4 ++-- block/blk-timeout.c | 2 +- fs/block_dev.c | 4 ++-- include/linux/blkdev.h | 2 +- 5 files changed, 37 insertions(+), 16 deletions(-)