| Message ID | 20200623220311.8033-3-mcgrof@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: kdocify the request_queue | expand |
On 2020/06/24 7:03, Luis Chamberlain wrote: > Now that we have a template, expand on the kdoc form for > the request_queue data structure with documentation from > the rest of the members, *only* for information we already > had. > > This does not add any new documentation. This just shifts > documentation to kdoc form. > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > include/linux/blkdev.h | 139 ++++++++++++----------------------------- > 1 file changed, 40 insertions(+), 99 deletions(-) > > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index ea319c2b0593..d30bfef893b9 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -396,8 +396,38 @@ static inline int blkdev_zone_mgmt_ioctl(struct block_device *bdev, > > /** > * struct request_queue - block device driver request queue > + * @queue_ctx: software queue context > + * @queue_hw_ctx: hw dispatch queues > + * @queuedata: the queue owner gets to use this for whatever they like. > + * ll_rw_blk doesn't touch it. > + * @queue_flags: various queue flags, see %QUEUE_* below > + * @pm_only: Number of contexts that have called blk_set_pm_only(). If this > + * counter is above zero then only %RQF_PM and %RQF_PREEMPT requests are > + * processed. > + * @id: ida allocated id for this queue. Used to index queues from ioctx. > + * @bounce_gfp: queue needs bounce pages for pages above this limit > + * @kobj: queue kobject > + * @mq_kobj: mq queue kobject > + * @nr_requests: maximum number of of requests > + * @ksm: Inline crypto capabilities > + * @nr_zones: Above line is not needed, no ? > + * @nr_zones: total number of zones of the device. This is always 0 for regular > + * block devices. May be: "total number of zones for a zoned block device. This is..." > + * @conv_zones_bitmap: bitmap of nr_zones bits which indicates if a zone > + * is conventional (bit set) or sequential (bit clear). > + * @seq_zones_wlock: bitmap of nr_zones bits which indicates if a zone > + * is write locked, that is, if a write request targeting the zone was > + * dispatched. > + * @debugfs_mutex: used to protect access to the @ebugfs_dir > * @debugfs_mutex: used to protect access to the @debugfs_dir > * @blk_trace: used by blktrace to keep track of setup / tracing > + * @fq: for flush operations > + * @td: throttle data > + * @unused_hctx_list: list used for reusing dead hctx instance in case of > + * updating nr_hw_queues. > + * @unused_hctx_lock: used to protect the @unused_hctx_list > + * @mq_freeze_lock: protects concurrent access to q_usage_counter by > + * percpu_ref_kill() and percpu_ref_reinit(). > * @debugfs_dir: directory created to place debugfs information. This is always > * created for make_request and request-based block drivers upon > * initialization. blktrace requires for this directory to be created, > @@ -413,67 +443,35 @@ static inline int blkdev_zone_mgmt_ioctl(struct block_device *bdev, > * o custom solutions such as scsi-generic > * > * All partitions share the same request_queue data structure. > + * > + * Zoned block device dispatch control is managed by the fields @nr_zones, > + * @conv_zones_bitmap and @seq_zones_wlock. These fields are fields are> + * initialized by the low level device driver (e.g. scsi/sd.c). Stacking > + * drivers (device mappers) may or may not initialize these fields. > + * Reads of this information must be protected with blk_queue_enter() / > + * blk_queue_exit(). Modifying this information is only allowed while > + * no requests are being processed. See also blk_mq_freeze_queue() and > + * blk_mq_unfreeze_queue(). Ooops... This is outdated... This should be: * Dispatch of write commands to zoned block devices is controlled using the * fields @nr_zones, @conv_zones_bitmap and @seq_zones_wlock. These fields are * initialized using the blk_revalidate_disk_zones() function from the level * request based device drivers (e.g. scsi/sd.c). BIO based drivers, if needed, * can initialize these fields directly. Accesses to these fields must be * protected with blk_queue_enter() / blk_queue_exit(). Modification of the * @nr_zones field and reallocation of the @conv_zones_bitmap and * @seq_zones_wlock bitmaps is only allowed while no requests are being * processed. See also blk_mq_freeze_queue() and blk_mq_unfreeze_queue(). > */ > struct request_queue { > struct request *last_merge; > struct elevator_queue *elevator; > - > struct blk_queue_stats *stats; > struct rq_qos *rq_qos; > - > make_request_fn *make_request_fn; > - > const struct blk_mq_ops *mq_ops; > - > - /* sw queues */ > struct blk_mq_ctx __percpu *queue_ctx; > - > unsigned int queue_depth; > - > - /* hw dispatch queues */ > struct blk_mq_hw_ctx **queue_hw_ctx; > unsigned int nr_hw_queues; > - > struct backing_dev_info *backing_dev_info; > - > - /* > - * The queue owner gets to use this for whatever they like. > - * ll_rw_blk doesn't touch it. > - */ > void *queuedata; > - > - /* > - * various queue flags, see QUEUE_* below > - */ > unsigned long queue_flags; > - /* > - * Number of contexts that have called blk_set_pm_only(). If this > - * counter is above zero then only RQF_PM and RQF_PREEMPT requests are > - * processed. > - */ > atomic_t pm_only; > - > - /* > - * ida allocated id for this queue. Used to index queues from > - * ioctx. > - */ > int id; > - > - /* > - * queue needs bounce pages for pages above this limit > - */ > gfp_t bounce_gfp; > - > spinlock_t queue_lock; > - > - /* > - * queue kobject > - */ > struct kobject kobj; > - > - /* > - * mq queue kobject > - */ > struct kobject *mq_kobj; > > #ifdef CONFIG_BLK_DEV_INTEGRITY > @@ -485,66 +483,32 @@ struct request_queue { > int rpm_status; > unsigned int nr_pending; > #endif > - > - /* > - * queue settings > - */ > - unsigned long nr_requests; /* Max # of requests */ > - > + unsigned long nr_requests; > unsigned int dma_pad_mask; > unsigned int dma_alignment; > - > #ifdef CONFIG_BLK_INLINE_ENCRYPTION > - /* Inline crypto capabilities */ > struct blk_keyslot_manager *ksm; > #endif > - > unsigned int rq_timeout; > int poll_nsec; > - > struct blk_stat_callback *poll_cb; > struct blk_rq_stat poll_stat[BLK_MQ_POLL_STATS_BKTS]; > - > struct timer_list timeout; > struct work_struct timeout_work; > - > struct list_head icq_list; > #ifdef CONFIG_BLK_CGROUP > DECLARE_BITMAP (blkcg_pols, BLKCG_MAX_POLS); > struct blkcg_gq *root_blkg; > struct list_head blkg_list; > #endif > - > struct queue_limits limits; > - > unsigned int required_elevator_features; > - > #ifdef CONFIG_BLK_DEV_ZONED > - /* > - * Zoned block device information for request dispatch control. > - * nr_zones is the total number of zones of the device. This is always > - * 0 for regular block devices. conv_zones_bitmap is a bitmap of nr_zones > - * bits which indicates if a zone is conventional (bit set) or > - * sequential (bit clear). seq_zones_wlock is a bitmap of nr_zones > - * bits which indicates if a zone is write locked, that is, if a write > - * request targeting the zone was dispatched. All three fields are > - * initialized by the low level device driver (e.g. scsi/sd.c). > - * Stacking drivers (device mappers) may or may not initialize > - * these fields. > - * > - * Reads of this information must be protected with blk_queue_enter() / > - * blk_queue_exit(). Modifying this information is only allowed while > - * no requests are being processed. See also blk_mq_freeze_queue() and > - * blk_mq_unfreeze_queue(). > - */ > unsigned int nr_zones; > unsigned long *conv_zones_bitmap; > unsigned long *seq_zones_wlock; > #endif /* CONFIG_BLK_DEV_ZONED */ > > - /* > - * sg stuff > - */ > unsigned int sg_timeout; > unsigned int sg_reserved_size; > int node; > @@ -552,59 +516,36 @@ struct request_queue { > #ifdef CONFIG_BLK_DEV_IO_TRACE > struct blk_trace __rcu *blk_trace; > #endif > - /* > - * for flush operations > - */ > struct blk_flush_queue *fq; > - > struct list_head requeue_list; > spinlock_t requeue_lock; > struct delayed_work requeue_work; > - > struct mutex sysfs_lock; > struct mutex sysfs_dir_lock; > - > - /* > - * for reusing dead hctx instance in case of updating > - * nr_hw_queues > - */ > struct list_head unused_hctx_list; > spinlock_t unused_hctx_lock; > - > int mq_freeze_depth; > - > #if defined(CONFIG_BLK_DEV_BSG) > struct bsg_class_device bsg_dev; > #endif > > #ifdef CONFIG_BLK_DEV_THROTTLING > - /* Throttle data */ > struct throtl_data *td; > #endif > struct rcu_head rcu_head; > wait_queue_head_t mq_freeze_wq; > - /* > - * Protect concurrent access to q_usage_counter by > - * percpu_ref_kill() and percpu_ref_reinit(). > - */ > struct mutex mq_freeze_lock; > struct percpu_ref q_usage_counter; > - > struct blk_mq_tag_set *tag_set; > struct list_head tag_set_list; > struct bio_set bio_split; > - > struct dentry *debugfs_dir; > - > #ifdef CONFIG_BLK_DEBUG_FS > struct dentry *sched_debugfs_dir; > struct dentry *rqos_debugfs_dir; > #endif > - > bool mq_sysfs_init_done; > - > size_t cmd_size; > - > #define BLK_MAX_WRITE_HINTS 5 > u64 write_hints[BLK_MAX_WRITE_HINTS]; > }; >
On 24/06/2020 00:03, Luis Chamberlain wrote: > + * @debugfs_mutex: used to protect access to the @ebugfs_dir > * @debugfs_mutex: used to protect access to the @debugfs_dir This line is duplicated and one of dups has a typo 'ebugfs_dir'
On 2020-06-23 15:03, Luis Chamberlain wrote: > /** > * struct request_queue - block device driver request queue > + * @queue_ctx: software queue context To me the description "software queues" is much more clear than "software queue context". I wouldn't mind if the queue_ctx member variable would be renamed to make its role more clear. Please also mention that there is one software queue per CPU. > + * @queue_hw_ctx: hw dispatch queues How about mentioning that requests flow from software queues into hardware queues, from hardware queues to the storage controller and also that the block driver controls the number of hardware queues? > + * @queuedata: the queue owner gets to use this for whatever they like. > + * ll_rw_blk doesn't touch it. How about changing "queue owner" into "block driver"? Please leave out the reference to ll_rw_blk since that source file was removed in 2008. See also commit a168ee84c90b ("block: first step of splitting ll_rw_blk, rename it"). > + * @id: ida allocated id for this queue. Used to index queues from ioctx. It seems to me that this ID is not only used to associate an ioctx with a request queue but also to associate a block cgroup with a request queue? See also blkg_lookup_slowpath(). > + * @bounce_gfp: queue needs bounce pages for pages above this limit > + * @kobj: queue kobject Please mention the path of this object, namely /sys/block/${bdev}/queue. > + * @mq_kobj: mq queue kobject Please mention the path of this object too, namely /sys/block/${bdev}/mq. > + * @nr_requests: maximum number of of requests Double "of"? Please mention that this is the maximum number of requests per hardware queue. There is one set of tags per hardware queue and each hardware queue has 'nr_requests' tags. See also queue_requests_store() and blk_mq_update_nr_requests(). > + * @ksm: Inline crypto capabilities > + * @nr_zones: > + * @nr_zones: total number of zones of the device. This is always 0 for regular > + * block devices. "@nr_zones" occurs twice? > + * @debugfs_mutex: used to protect access to the @ebugfs_dir > * @debugfs_mutex: used to protect access to the @debugfs_dir Double "@debugfs_mutex"? Thanks, Bart.
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index ea319c2b0593..d30bfef893b9 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -396,8 +396,38 @@ static inline int blkdev_zone_mgmt_ioctl(struct block_device *bdev, /** * struct request_queue - block device driver request queue + * @queue_ctx: software queue context + * @queue_hw_ctx: hw dispatch queues + * @queuedata: the queue owner gets to use this for whatever they like. + * ll_rw_blk doesn't touch it. + * @queue_flags: various queue flags, see %QUEUE_* below + * @pm_only: Number of contexts that have called blk_set_pm_only(). If this + * counter is above zero then only %RQF_PM and %RQF_PREEMPT requests are + * processed. + * @id: ida allocated id for this queue. Used to index queues from ioctx. + * @bounce_gfp: queue needs bounce pages for pages above this limit + * @kobj: queue kobject + * @mq_kobj: mq queue kobject + * @nr_requests: maximum number of of requests + * @ksm: Inline crypto capabilities + * @nr_zones: + * @nr_zones: total number of zones of the device. This is always 0 for regular + * block devices. + * @conv_zones_bitmap: bitmap of nr_zones bits which indicates if a zone + * is conventional (bit set) or sequential (bit clear). + * @seq_zones_wlock: bitmap of nr_zones bits which indicates if a zone + * is write locked, that is, if a write request targeting the zone was + * dispatched. + * @debugfs_mutex: used to protect access to the @ebugfs_dir * @debugfs_mutex: used to protect access to the @debugfs_dir * @blk_trace: used by blktrace to keep track of setup / tracing + * @fq: for flush operations + * @td: throttle data + * @unused_hctx_list: list used for reusing dead hctx instance in case of + * updating nr_hw_queues. + * @unused_hctx_lock: used to protect the @unused_hctx_list + * @mq_freeze_lock: protects concurrent access to q_usage_counter by + * percpu_ref_kill() and percpu_ref_reinit(). * @debugfs_dir: directory created to place debugfs information. This is always * created for make_request and request-based block drivers upon * initialization. blktrace requires for this directory to be created, @@ -413,67 +443,35 @@ static inline int blkdev_zone_mgmt_ioctl(struct block_device *bdev, * o custom solutions such as scsi-generic * * All partitions share the same request_queue data structure. + * + * Zoned block device dispatch control is managed by the fields @nr_zones, + * @conv_zones_bitmap and @seq_zones_wlock. These fields are fields are + * initialized by the low level device driver (e.g. scsi/sd.c). Stacking + * drivers (device mappers) may or may not initialize these fields. + * Reads of this information must be protected with blk_queue_enter() / + * blk_queue_exit(). Modifying this information is only allowed while + * no requests are being processed. See also blk_mq_freeze_queue() and + * blk_mq_unfreeze_queue(). */ struct request_queue { struct request *last_merge; struct elevator_queue *elevator; - struct blk_queue_stats *stats; struct rq_qos *rq_qos; - make_request_fn *make_request_fn; - const struct blk_mq_ops *mq_ops; - - /* sw queues */ struct blk_mq_ctx __percpu *queue_ctx; - unsigned int queue_depth; - - /* hw dispatch queues */ struct blk_mq_hw_ctx **queue_hw_ctx; unsigned int nr_hw_queues; - struct backing_dev_info *backing_dev_info; - - /* - * The queue owner gets to use this for whatever they like. - * ll_rw_blk doesn't touch it. - */ void *queuedata; - - /* - * various queue flags, see QUEUE_* below - */ unsigned long queue_flags; - /* - * Number of contexts that have called blk_set_pm_only(). If this - * counter is above zero then only RQF_PM and RQF_PREEMPT requests are - * processed. - */ atomic_t pm_only; - - /* - * ida allocated id for this queue. Used to index queues from - * ioctx. - */ int id; - - /* - * queue needs bounce pages for pages above this limit - */ gfp_t bounce_gfp; - spinlock_t queue_lock; - - /* - * queue kobject - */ struct kobject kobj; - - /* - * mq queue kobject - */ struct kobject *mq_kobj; #ifdef CONFIG_BLK_DEV_INTEGRITY @@ -485,66 +483,32 @@ struct request_queue { int rpm_status; unsigned int nr_pending; #endif - - /* - * queue settings - */ - unsigned long nr_requests; /* Max # of requests */ - + unsigned long nr_requests; unsigned int dma_pad_mask; unsigned int dma_alignment; - #ifdef CONFIG_BLK_INLINE_ENCRYPTION - /* Inline crypto capabilities */ struct blk_keyslot_manager *ksm; #endif - unsigned int rq_timeout; int poll_nsec; - struct blk_stat_callback *poll_cb; struct blk_rq_stat poll_stat[BLK_MQ_POLL_STATS_BKTS]; - struct timer_list timeout; struct work_struct timeout_work; - struct list_head icq_list; #ifdef CONFIG_BLK_CGROUP DECLARE_BITMAP (blkcg_pols, BLKCG_MAX_POLS); struct blkcg_gq *root_blkg; struct list_head blkg_list; #endif - struct queue_limits limits; - unsigned int required_elevator_features; - #ifdef CONFIG_BLK_DEV_ZONED - /* - * Zoned block device information for request dispatch control. - * nr_zones is the total number of zones of the device. This is always - * 0 for regular block devices. conv_zones_bitmap is a bitmap of nr_zones - * bits which indicates if a zone is conventional (bit set) or - * sequential (bit clear). seq_zones_wlock is a bitmap of nr_zones - * bits which indicates if a zone is write locked, that is, if a write - * request targeting the zone was dispatched. All three fields are - * initialized by the low level device driver (e.g. scsi/sd.c). - * Stacking drivers (device mappers) may or may not initialize - * these fields. - * - * Reads of this information must be protected with blk_queue_enter() / - * blk_queue_exit(). Modifying this information is only allowed while - * no requests are being processed. See also blk_mq_freeze_queue() and - * blk_mq_unfreeze_queue(). - */ unsigned int nr_zones; unsigned long *conv_zones_bitmap; unsigned long *seq_zones_wlock; #endif /* CONFIG_BLK_DEV_ZONED */ - /* - * sg stuff - */ unsigned int sg_timeout; unsigned int sg_reserved_size; int node; @@ -552,59 +516,36 @@ struct request_queue { #ifdef CONFIG_BLK_DEV_IO_TRACE struct blk_trace __rcu *blk_trace; #endif - /* - * for flush operations - */ struct blk_flush_queue *fq; - struct list_head requeue_list; spinlock_t requeue_lock; struct delayed_work requeue_work; - struct mutex sysfs_lock; struct mutex sysfs_dir_lock; - - /* - * for reusing dead hctx instance in case of updating - * nr_hw_queues - */ struct list_head unused_hctx_list; spinlock_t unused_hctx_lock; - int mq_freeze_depth; - #if defined(CONFIG_BLK_DEV_BSG) struct bsg_class_device bsg_dev; #endif #ifdef CONFIG_BLK_DEV_THROTTLING - /* Throttle data */ struct throtl_data *td; #endif struct rcu_head rcu_head; wait_queue_head_t mq_freeze_wq; - /* - * Protect concurrent access to q_usage_counter by - * percpu_ref_kill() and percpu_ref_reinit(). - */ struct mutex mq_freeze_lock; struct percpu_ref q_usage_counter; - struct blk_mq_tag_set *tag_set; struct list_head tag_set_list; struct bio_set bio_split; - struct dentry *debugfs_dir; - #ifdef CONFIG_BLK_DEBUG_FS struct dentry *sched_debugfs_dir; struct dentry *rqos_debugfs_dir; #endif - bool mq_sysfs_init_done; - size_t cmd_size; - #define BLK_MAX_WRITE_HINTS 5 u64 write_hints[BLK_MAX_WRITE_HINTS]; };
Now that we have a template, expand on the kdoc form for the request_queue data structure with documentation from the rest of the members, *only* for information we already had. This does not add any new documentation. This just shifts documentation to kdoc form. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> --- include/linux/blkdev.h | 139 ++++++++++++----------------------------- 1 file changed, 40 insertions(+), 99 deletions(-)