[PATCH] block: split out a new blk_plug.h helper

[PATCH] block: split out a new blk_plug.h helper

[Christoph Hellwig]

blkdev.h gets included in various places outside the block layer just
for struct blk_plug and related plugging functions.

Split blk_plug into a separate helper to reduce the amount of code
that needs to get rebuilt when blkdev.h changes and to slightly
reduce compile times.

In io_uring this requires pulling in a few other headers explicitly that
previously were implicitly included through blkdev.h.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/aio.c                       |  2 +-
 fs/fs-writeback.c              |  2 +-
 include/linux/blk_plug.h       | 95 ++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h         | 86 +-----------------------------
 include/linux/io_uring_types.h |  2 +-
 io_uring/io_uring.h            |  1 +
 io_uring/kbuf.c                |  1 +
 io_uring/rsrc.h                |  2 +
 io_uring/rw.h                  |  1 +
 kernel/exit.c                  |  1 -
 kernel/sched/core.c            |  1 -
 mm/madvise.c                   |  2 +-
 mm/page-writeback.c            |  1 -
 mm/readahead.c                 |  2 +-
 mm/swap_state.c                |  2 +-
 mm/vmscan.c                    |  2 +-
 16 files changed, 108 insertions(+), 95 deletions(-)
 create mode 100644 include/linux/blk_plug.h

diff --git a/fs/aio.c b/fs/aio.c
index f57fa21a2503..ebdb0e5b95fd 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -35,7 +35,7 @@
 #include <linux/workqueue.h>
 #include <linux/security.h>
 #include <linux/eventfd.h>
-#include <linux/blkdev.h>
+#include <linux/blk_plug.h>
 #include <linux/compat.h>
 #include <linux/migrate.h>
 #include <linux/ramfs.h>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index fdb8766d275a..d064072284f4 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -25,7 +25,7 @@
 #include <linux/pagemap.h>
 #include <linux/kthread.h>
 #include <linux/writeback.h>
-#include <linux/blkdev.h>
+#include <linux/blk_plug.h>
 #include <linux/backing-dev.h>
 #include <linux/tracepoint.h>
 #include <linux/device.h>
diff --git a/include/linux/blk_plug.h b/include/linux/blk_plug.h
new file mode 100644
index 000000000000..2ac1265662ad
--- /dev/null
+++ b/include/linux/blk_plug.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_BLK_PLUG_H
+#define _LINUX_BLK_PLUG_H
+
+#include <linux/sched.h>
+
+struct blk_plug_cb;
+typedef void (*blk_plug_cb_fn)(struct blk_plug_cb *cb, bool from_schedule);
+
+struct rq_list {
+	struct request *head;
+	struct request *tail;
+};
+
+#ifdef CONFIG_BLOCK
+/*
+ * blk_plug permits building a queue of related requests by holding the I/O
+ * fragments for a short period. This allows merging of sequential requests
+ * into single larger request. As the requests are moved from a per-task list to
+ * the device's request_queue in a batch, this results in improved scalability
+ * 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. For details, please see schedule() where
+ * blk_flush_plug() is called.
+ */
+struct blk_plug {
+	struct rq_list mq_list; /* blk-mq requests */
+
+	/* if ios_left is > 1, we can batch tag/rq allocations */
+	struct rq_list cached_rqs;
+	u64 cur_ktime;
+	unsigned short nr_ios;
+
+	unsigned short rq_count;
+
+	bool multiple_queues;
+	bool has_elevator;
+
+	struct list_head cb_list; /* md requires an unplug callback */
+};
+
+void blk_start_plug(struct blk_plug *);
+void blk_start_plug_nr_ios(struct blk_plug *, unsigned short);
+void blk_finish_plug(struct blk_plug *);
+
+void __blk_flush_plug(struct blk_plug *plug, bool from_schedule);
+static inline void blk_flush_plug(struct blk_plug *plug, bool async)
+{
+	if (plug)
+		__blk_flush_plug(plug, async);
+}
+
+static __always_inline void blk_plug_invalidate_ts(void)
+{
+	if (unlikely(current->flags & PF_BLOCK_TS)) {
+		current->plug->cur_ktime = 0;
+		current->flags &= ~PF_BLOCK_TS;
+	}
+}
+
+struct blk_plug_cb {
+	struct list_head list;
+	blk_plug_cb_fn callback;
+	void *data;
+};
+
+struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
+		int size);
+#else /* CONFIG_BLOCK */
+struct blk_plug {
+};
+
+static inline void blk_start_plug(struct blk_plug *plug)
+{
+}
+
+static inline void blk_start_plug_nr_ios(struct blk_plug *plug,
+					 unsigned short nr_ios)
+{
+}
+
+static inline void blk_finish_plug(struct blk_plug *plug)
+{
+}
+
+static inline void blk_flush_plug(struct blk_plug *plug, bool async)
+{
+}
+
+static inline void blk_plug_invalidate_ts(void)
+{
+}
+#endif /* CONFIG_BLOCK */
+#endif /* _LINUX_BLK_PLUG_H */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9213a5716f95..20cb8ed7d987 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -7,6 +7,7 @@
 
 #include <linux/types.h>
 #include <linux/blk_types.h>
+#include <linux/blk_plug.h>
 #include <linux/device.h>
 #include <linux/list.h>
 #include <linux/llist.h>
@@ -21,7 +22,6 @@
 #include <linux/rcupdate.h>
 #include <linux/percpu-refcount.h>
 #include <linux/blkzoned.h>
-#include <linux/sched.h>
 #include <linux/sbitmap.h>
 #include <linux/uuid.h>
 #include <linux/xarray.h>
@@ -1169,94 +1169,10 @@ extern void blk_put_queue(struct request_queue *);
 
 void blk_mark_disk_dead(struct gendisk *disk);
 
-struct rq_list {
-	struct request *head;
-	struct request *tail;
-};
-
 #ifdef CONFIG_BLOCK
-/*
- * blk_plug permits building a queue of related requests by holding the I/O
- * fragments for a short period. This allows merging of sequential requests
- * into single larger request. As the requests are moved from a per-task list to
- * the device's request_queue in a batch, this results in improved scalability
- * 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. For details, please see schedule() where
- * blk_flush_plug() is called.
- */
-struct blk_plug {
-	struct rq_list mq_list; /* blk-mq requests */
-
-	/* if ios_left is > 1, we can batch tag/rq allocations */
-	struct rq_list cached_rqs;
-	u64 cur_ktime;
-	unsigned short nr_ios;
-
-	unsigned short rq_count;
-
-	bool multiple_queues;
-	bool has_elevator;
-
-	struct list_head cb_list; /* md requires an unplug callback */
-};
-
-struct blk_plug_cb;
-typedef void (*blk_plug_cb_fn)(struct blk_plug_cb *, bool);
-struct blk_plug_cb {
-	struct list_head list;
-	blk_plug_cb_fn callback;
-	void *data;
-};
-extern struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug,
-					     void *data, int size);
-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 *);
-
-void __blk_flush_plug(struct blk_plug *plug, bool from_schedule);
-static inline void blk_flush_plug(struct blk_plug *plug, bool async)
-{
-	if (plug)
-		__blk_flush_plug(plug, async);
-}
-
-static __always_inline void blk_plug_invalidate_ts(void)
-{
-	if (unlikely(current->flags & PF_BLOCK_TS)) {
-		current->plug->cur_ktime = 0;
-		current->flags &= ~PF_BLOCK_TS;
-	}
-}
-
 int blkdev_issue_flush(struct block_device *bdev);
 long nr_blockdev_pages(void);
 #else /* CONFIG_BLOCK */
-struct blk_plug {
-};
-
-static inline void blk_start_plug_nr_ios(struct blk_plug *plug,
-					 unsigned short nr_ios)
-{
-}
-
-static inline void blk_start_plug(struct blk_plug *plug)
-{
-}
-
-static inline void blk_finish_plug(struct blk_plug *plug)
-{
-}
-
-static inline void blk_flush_plug(struct blk_plug *plug, bool async)
-{
-}
-
-static inline void blk_plug_invalidate_ts(void)
-{
-}
-
 static inline int blkdev_issue_flush(struct block_device *bdev)
 {
 	return 0;
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index a2c623a67a25..f302bb3fcf8e 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -1,7 +1,7 @@
 #ifndef IO_URING_TYPES_H
 #define IO_URING_TYPES_H
 
-#include <linux/blkdev.h>
+#include <linux/blk_plug.h>
 #include <linux/hashtable.h>
 #include <linux/task_work.h>
 #include <linux/bitmap.h>
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index cb736b815422..9771d4557ed3 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -3,6 +3,7 @@
 #define IOU_CORE_H
 
 #include <linux/errno.h>
+#include <linux/file.h>
 #include <linux/lockdep.h>
 #include <linux/resume_user_mode.h>
 #include <linux/poll.h>
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 3cd29477fff2..e58bff9037f1 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -7,6 +7,7 @@
 #include <linux/slab.h>
 #include <linux/namei.h>
 #include <linux/poll.h>
+#include <linux/uio.h>
 #include <linux/vmalloc.h>
 #include <linux/io_uring.h>
 
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 98ae8ef51009..eacfdb70f203 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -2,8 +2,10 @@
 #ifndef IOU_RSRC_H
 #define IOU_RSRC_H
 
+#include <linux/bvec.h>
 #include <linux/io_uring_types.h>
 #include <linux/lockdep.h>
+#include <linux/uio.h>
 
 #define IO_VEC_CACHE_SOFT_CAP		256
 
diff --git a/io_uring/rw.h b/io_uring/rw.h
index 9bd7fbf70ea9..1179506f929f 100644
--- a/io_uring/rw.h
+++ b/io_uring/rw.h
@@ -2,6 +2,7 @@
 
 #include <linux/io_uring_types.h>
 #include <linux/pagemap.h>
+#include <linux/uio.h>
 
 struct io_meta_state {
 	u32			seed;
diff --git a/kernel/exit.c b/kernel/exit.c
index 1056422bc101..2140d0515f9e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -48,7 +48,6 @@
 #include <linux/audit.h> /* for audit_free() */
 #include <linux/resource.h>
 #include <linux/task_io_accounting_ops.h>
-#include <linux/blkdev.h>
 #include <linux/task_work.h>
 #include <linux/fs_struct.h>
 #include <linux/init_task.h>
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 96226707c2f6..616774777dea 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -40,7 +40,6 @@
 #include <linux/sched/rseq_api.h>
 #include <linux/sched/rt.h>
 
-#include <linux/blkdev.h>
 #include <linux/context_tracking.h>
 #include <linux/cpuset.h>
 #include <linux/delayacct.h>
diff --git a/mm/madvise.c b/mm/madvise.c
index cd9bb077072c..f6b7ef0f8b1b 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -25,7 +25,7 @@
 #include <linux/ksm.h>
 #include <linux/fs.h>
 #include <linux/file.h>
-#include <linux/blkdev.h>
+#include <linux/blk_plug.h>
 #include <linux/backing-dev.h>
 #include <linux/pagewalk.h>
 #include <linux/swap.h>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index e98748112d1e..d1fd6ba58ae5 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -25,7 +25,6 @@
 #include <linux/init.h>
 #include <linux/backing-dev.h>
 #include <linux/task_io_accounting_ops.h>
-#include <linux/blkdev.h>
 #include <linux/mpage.h>
 #include <linux/rmap.h>
 #include <linux/percpu.h>
diff --git a/mm/readahead.c b/mm/readahead.c
index 558c92957518..6e5563290287 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -113,7 +113,7 @@
  * ->read_folio() which may be less efficient.
  */
 
-#include <linux/blkdev.h>
+#include <linux/blk_plug.h>
 #include <linux/kernel.h>
 #include <linux/dax.h>
 #include <linux/gfp.h>
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 9c3a5cf99778..727a17ee7821 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -17,7 +17,7 @@
 #include <linux/pagemap.h>
 #include <linux/folio_batch.h>
 #include <linux/backing-dev.h>
-#include <linux/blkdev.h>
+#include <linux/blk_plug.h>
 #include <linux/migrate.h>
 #include <linux/vmalloc.h>
 #include <linux/huge_mm.h>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 35c3bb15ae96..b957664abb26 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -25,7 +25,7 @@
 #include <linux/vmstat.h>
 #include <linux/file.h>
 #include <linux/writeback.h>
-#include <linux/blkdev.h>
+#include <linux/blk_plug.h>
 #include <linux/buffer_head.h>	/* for buffer_heads_over_limit */
 #include <linux/mm_inline.h>
 #include <linux/backing-dev.h>
-- 
2.53.0

Re: [PATCH] block: split out a new blk_plug.h helper

[Johannes Thumshirn]

On 7/6/26 6:11 AM, Christoph Hellwig wrote:
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 9213a5716f95..20cb8ed7d987 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -7,6 +7,7 @@
>   
>   #include <linux/types.h>
>   #include <linux/blk_types.h>
> +#include <linux/blk_plug.h>
>   #include <linux/device.h>
>   #include <linux/list.h>
>   #include <linux/llist.h>
>
I know it's a lot of cross subsystem churn, but wouldn't it be cleaner 
to not include blk_plug.h in blkdev.h, but patch the update the 
consumers? A quick grep shows 68 files that would need updating and some 
you already  have updated.

Re: [PATCH] block: split out a new blk_plug.h helper

[Christoph Hellwig]

On Mon, Jul 06, 2026 at 08:38:12AM +0200, Johannes Thumshirn wrote:
> On 7/6/26 6:11 AM, Christoph Hellwig wrote:
>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
>> index 9213a5716f95..20cb8ed7d987 100644
>> --- a/include/linux/blkdev.h
>> +++ b/include/linux/blkdev.h
>> @@ -7,6 +7,7 @@
>>     #include <linux/types.h>
>>   #include <linux/blk_types.h>
>> +#include <linux/blk_plug.h>
>>   #include <linux/device.h>
>>   #include <linux/list.h>
>>   #include <linux/llist.h>
>>
> I know it's a lot of cross subsystem churn, but wouldn't it be cleaner to 
> not include blk_plug.h in blkdev.h, but patch the update the consumers? A 
> quick grep shows 68 files that would need updating and some you already  
> have updated.

Right now blkdev.h needs the rq_list from it.  So we'd need to move
that to linux/types.h or something first, which feels a bit iffy.

And no, including blk_types.h in blk_plug.h is not a solution,
as that is still touched far too often.

Re: [PATCH] block: split out a new blk_plug.h helper

[Johannes Thumshirn]

On 7/6/26 8:45 AM, Christoph Hellwig wrote:
> On Mon, Jul 06, 2026 at 08:38:12AM +0200, Johannes Thumshirn wrote:
>> On 7/6/26 6:11 AM, Christoph Hellwig wrote:
>>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
>>> index 9213a5716f95..20cb8ed7d987 100644
>>> --- a/include/linux/blkdev.h
>>> +++ b/include/linux/blkdev.h
>>> @@ -7,6 +7,7 @@
>>>      #include <linux/types.h>
>>>    #include <linux/blk_types.h>
>>> +#include <linux/blk_plug.h>
>>>    #include <linux/device.h>
>>>    #include <linux/list.h>
>>>    #include <linux/llist.h>
>>>
>> I know it's a lot of cross subsystem churn, but wouldn't it be cleaner to
>> not include blk_plug.h in blkdev.h, but patch the update the consumers? A
>> quick grep shows 68 files that would need updating and some you already
>> have updated.
> Right now blkdev.h needs the rq_list from it.  So we'd need to move
> that to linux/types.h or something first, which feels a bit iffy.
>
> And no, including blk_types.h in blk_plug.h is not a solution,
> as that is still touched far too often.

Ah sh*t I did miss rq_list. Fair enough.


Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Re: [PATCH] block: split out a new blk_plug.h helper

[Damien Le Moal]

On 7/6/26 1:11 PM, Christoph Hellwig wrote:
> blkdev.h gets included in various places outside the block layer just
> for struct blk_plug and related plugging functions.
> 
> Split blk_plug into a separate helper to reduce the amount of code
> that needs to get rebuilt when blkdev.h changes and to slightly
> reduce compile times.
> 
> In io_uring this requires pulling in a few other headers explicitly that
> previously were implicitly included through blkdev.h.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

A couple of nits below (not entirely sure if they make sense).
But otherwise looks OK to me.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

> diff --git a/include/linux/blk_plug.h b/include/linux/blk_plug.h
> new file mode 100644
> index 000000000000..2ac1265662ad
> --- /dev/null
> +++ b/include/linux/blk_plug.h
> @@ -0,0 +1,95 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_BLK_PLUG_H
> +#define _LINUX_BLK_PLUG_H
> +
> +#include <linux/sched.h>

struct blk_plug_cb has a list_head. So maybe also add

#include <linux/types.h>

?

> +
> +struct blk_plug_cb;

Maybe add "struct request;" here too ?

> +typedef void (*blk_plug_cb_fn)(struct blk_plug_cb *cb, bool from_schedule);
> +
> +struct rq_list {
> +	struct request *head;
> +	struct request *tail;
> +};


-- 
Damien Le Moal
Western Digital Research

Re: [PATCH] block: split out a new blk_plug.h helper

[Christoph Hellwig]

On Mon, Jul 06, 2026 at 04:04:48PM +0900, Damien Le Moal wrote:
> > +#include <linux/sched.h>
> 
> struct blk_plug_cb has a list_head. So maybe also add
> 
> #include <linux/types.h>
> 
> ?

That already gets pulled in.

> > +
> > +struct blk_plug_cb;
> 
> Maybe add "struct request;" here too ?

No need for type forward declarations when the types are only used
for pointers in structs (or as pointer variables).  They are needed
only when pointers to the type are used in prototypes.

Re: [PATCH] block: split out a new blk_plug.h helper

[Christian Brauner]

> blkdev.h gets included in various places outside the block layer just
> for struct blk_plug and related plugging functions.
> 
> Split blk_plug into a separate helper to reduce the amount of code
> that needs to get rebuilt when blkdev.h changes and to slightly
> reduce compile times.
> 
> In io_uring this requires pulling in a few other headers explicitly that
> previously were implicitly included through blkdev.h.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Christian Brauner (Amutable) <brauner@kernel.org>

-- 
Christian Brauner <brauner@kernel.org>