[v11,4/7] dm: enable synchronous dax
diff mbox series

Message ID 20190610090730.8589-5-pagupta@redhat.com
State Superseded
Headers show
Series
  • virtio pmem driver
Related show

Commit Message

Pankaj Gupta June 10, 2019, 9:07 a.m. UTC
This patch sets dax device 'DAXDEV_SYNC' flag if all the target
 devices of device mapper support synchrononous DAX. If device
 mapper consists of both synchronous and asynchronous dax devices,
 we don't set 'DAXDEV_SYNC' flag.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
---
 drivers/md/dm-table.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Comments

Mike Snitzer June 10, 2019, 7:28 p.m. UTC | #1
On Mon, Jun 10 2019 at  5:07am -0400,
Pankaj Gupta <pagupta@redhat.com> wrote:

>  This patch sets dax device 'DAXDEV_SYNC' flag if all the target
>  devices of device mapper support synchrononous DAX. If device
>  mapper consists of both synchronous and asynchronous dax devices,
>  we don't set 'DAXDEV_SYNC' flag.
> 
> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
> ---
>  drivers/md/dm-table.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 350cf0451456..c5160d846fe6 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -890,10 +890,17 @@ static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
>  			start, len);
>  }
>  
> +static int device_synchronous(struct dm_target *ti, struct dm_dev *dev,
> +				       sector_t start, sector_t len, void *data)
> +{
> +	return dax_synchronous(dev->dax_dev);
> +}
> +
>  bool dm_table_supports_dax(struct dm_table *t, int blocksize)
>  {
>  	struct dm_target *ti;
>  	unsigned i;
> +	bool dax_sync = true;
>  
>  	/* Ensure that all targets support DAX. */
>  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
> @@ -906,7 +913,14 @@ bool dm_table_supports_dax(struct dm_table *t, int blocksize)
>  		    !ti->type->iterate_devices(ti, device_supports_dax,
>  			    &blocksize))
>  			return false;
> +
> +		/* Check devices support synchronous DAX */
> +		if (dax_sync &&
> +		    !ti->type->iterate_devices(ti, device_synchronous, NULL))
> +			dax_sync = false;
>  	}
> +	if (dax_sync)
> +		set_dax_synchronous(t->md->dax_dev);
>  
>  	return true;
>  }
> -- 
> 2.20.1
> 

dm_table_supports_dax() is called multiple times (from
dm_table_set_restrictions and dm_table_determine_type).  It is strange
to have a getter have a side-effect of being a setter too.  Overloading
like this could get you in trouble in the future.

Are you certain this is what you want?

Or would it be better to refactor dm_table_supports_dax() to take an
iterate_devices_fn arg and have callers pass the appropriate function?
Then have dm_table_set_restrictions() caller do:

     if (dm_table_supports_dax(t, device_synchronous, NULL))
     	  set_dax_synchronous(t->md->dax_dev);

(NULL arg implies dm_table_supports_dax() refactoring would take a int
*data pointer rather than int type).

Mike
Pankaj Gupta June 11, 2019, 1:10 p.m. UTC | #2
Hi Mike,

Thanks for the review Please find my reply inline.

> 
> dm_table_supports_dax() is called multiple times (from
> dm_table_set_restrictions and dm_table_determine_type).  It is strange
> to have a getter have a side-effect of being a setter too.  Overloading
> like this could get you in trouble in the future.
> 
> Are you certain this is what you want?

I agree with you.

> 
> Or would it be better to refactor dm_table_supports_dax() to take an
> iterate_devices_fn arg and have callers pass the appropriate function?
> Then have dm_table_set_restrictions() caller do:
> 
>      if (dm_table_supports_dax(t, device_synchronous, NULL))
>                set_dax_synchronous(t->md->dax_dev);
> 
> (NULL arg implies dm_table_supports_dax() refactoring would take a int
> *data pointer rather than int type).
> 
> Mike
> 

I am sending below patch as per your suggestion. Does it look
near to what you have in mind?

Thank you,
Pankaj

===============

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 350cf0451456..8d89acc8b8c2 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -881,7 +881,7 @@ void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type)
 EXPORT_SYMBOL_GPL(dm_table_set_type);

 /* validate the dax capability of the target device span */
-static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
+int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
                                       sector_t start, sector_t len, void *data)
 {
        int blocksize = *(int *) data;
@@ -890,7 +890,15 @@ static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
                        start, len);
 }

-bool dm_table_supports_dax(struct dm_table *t, int blocksize)
+/* Check devices support synchronous DAX */
+static int device_synchronous(struct dm_target *ti, struct dm_dev *dev,
+                                      sector_t start, sector_t len, void *data)
+{
+       return dax_synchronous(dev->dax_dev);
+}
+
+bool dm_table_supports_dax(struct dm_table *t,
+                         iterate_devices_callout_fn iterate_fn, int *blocksize)
 {
        struct dm_target *ti;
        unsigned i;
@@ -903,8 +911,7 @@ bool dm_table_supports_dax(struct dm_table *t, int blocksize)
                        return false;

                if (!ti->type->iterate_devices ||
-                   !ti->type->iterate_devices(ti, device_supports_dax,
-                           &blocksize))
+                       !ti->type->iterate_devices(ti, iterate_fn, blocksize))
                        return false;
        }

@@ -940,6 +947,7 @@ static int dm_table_determine_type(struct dm_table *t)
        struct dm_target *tgt;
        struct list_head *devices = dm_table_get_devices(t);
        enum dm_queue_mode live_md_type = dm_get_md_type(t->md);
+       int page_size = PAGE_SIZE;

        if (t->type != DM_TYPE_NONE) {
                /* target already set the table's type */
@@ -984,7 +992,7 @@ static int dm_table_determine_type(struct dm_table *t)
 verify_bio_based:
                /* We must use this table as bio-based */
                t->type = DM_TYPE_BIO_BASED;
-               if (dm_table_supports_dax(t, PAGE_SIZE) ||
+               if (dm_table_supports_dax(t, device_supports_dax, &page_size) ||
                    (list_empty(devices) && live_md_type == DM_TYPE_DAX_BIO_BASED)) {
                        t->type = DM_TYPE_DAX_BIO_BASED;
                } else {
@@ -1883,6 +1891,7 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
                               struct queue_limits *limits)
 {
        bool wc = false, fua = false;
+       int page_size = PAGE_SIZE;

        /*
         * Copy table's limits to the DM device's request_queue
@@ -1910,8 +1919,13 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
        }
        blk_queue_write_cache(q, wc, fua);

-       if (dm_table_supports_dax(t, PAGE_SIZE))
+       if (dm_table_supports_dax(t, device_supports_dax, &page_size)) {
+
                blk_queue_flag_set(QUEUE_FLAG_DAX, q);
+               if (dm_table_supports_dax(t, device_synchronous, NULL))
+                       set_dax_synchronous(t->md->dax_dev);
+       }
        else
                blk_queue_flag_clear(QUEUE_FLAG_DAX, q);

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b1caa7188209..b92c42a72ad4 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1119,7 +1119,7 @@ static bool dm_dax_supported(struct dax_device *dax_dev, struct block_device *bd
        if (!map)
                return false;

-       ret = dm_table_supports_dax(map, blocksize);
+       ret = dm_table_supports_dax(map, device_supports_dax, &blocksize);

        dm_put_live_table(md, srcu_idx);

diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 17e3db54404c..0475673337f3 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -72,7 +72,10 @@ bool dm_table_bio_based(struct dm_table *t);
 bool dm_table_request_based(struct dm_table *t);
 void dm_table_free_md_mempools(struct dm_table *t);
 struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
-bool dm_table_supports_dax(struct dm_table *t, int blocksize);
+bool dm_table_supports_dax(struct dm_table *t, iterate_devices_callout_fn fn,
+                          int *blocksize);
+int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
+                          sector_t start, sector_t len, void *data);

 void dm_lock_md_type(struct mapped_device *md);
 void dm_unlock_md_type(struct mapped_device *md);
--
2.20.1
Mike Snitzer June 11, 2019, 3:04 p.m. UTC | #3
On Tue, Jun 11 2019 at  9:10am -0400,
Pankaj Gupta <pagupta@redhat.com> wrote:

> Hi Mike,
> 
> Thanks for the review Please find my reply inline.
> 
> > 
> > dm_table_supports_dax() is called multiple times (from
> > dm_table_set_restrictions and dm_table_determine_type).  It is strange
> > to have a getter have a side-effect of being a setter too.  Overloading
> > like this could get you in trouble in the future.
> > 
> > Are you certain this is what you want?
> 
> I agree with you.
> 
> > 
> > Or would it be better to refactor dm_table_supports_dax() to take an
> > iterate_devices_fn arg and have callers pass the appropriate function?
> > Then have dm_table_set_restrictions() caller do:
> > 
> >      if (dm_table_supports_dax(t, device_synchronous, NULL))
> >                set_dax_synchronous(t->md->dax_dev);
> > 
> > (NULL arg implies dm_table_supports_dax() refactoring would take a int
> > *data pointer rather than int type).
> > 
> > Mike
> > 
> 
> I am sending below patch as per your suggestion. Does it look
> near to what you have in mind?

Yes, it does.. just one nit I noticed inlined below.

> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 350cf0451456..8d89acc8b8c2 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c

...

> @@ -1910,8 +1919,13 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
>         }
>         blk_queue_write_cache(q, wc, fua);
> 
> -       if (dm_table_supports_dax(t, PAGE_SIZE))
> +       if (dm_table_supports_dax(t, device_supports_dax, &page_size)) {
> +

No need for an empty newline here ^

>                 blk_queue_flag_set(QUEUE_FLAG_DAX, q);
> +               if (dm_table_supports_dax(t, device_synchronous, NULL))
> +                       set_dax_synchronous(t->md->dax_dev);
> +       }
>         else
>                 blk_queue_flag_clear(QUEUE_FLAG_DAX, q);
> 

Thanks,
Mike
Pankaj Gupta June 11, 2019, 4:04 p.m. UTC | #4
> 
> > Hi Mike,
> > 
> > Thanks for the review Please find my reply inline.
> > 
> > > 
> > > dm_table_supports_dax() is called multiple times (from
> > > dm_table_set_restrictions and dm_table_determine_type).  It is strange
> > > to have a getter have a side-effect of being a setter too.  Overloading
> > > like this could get you in trouble in the future.
> > > 
> > > Are you certain this is what you want?
> > 
> > I agree with you.
> > 
> > > 
> > > Or would it be better to refactor dm_table_supports_dax() to take an
> > > iterate_devices_fn arg and have callers pass the appropriate function?
> > > Then have dm_table_set_restrictions() caller do:
> > > 
> > >      if (dm_table_supports_dax(t, device_synchronous, NULL))
> > >                set_dax_synchronous(t->md->dax_dev);
> > > 
> > > (NULL arg implies dm_table_supports_dax() refactoring would take a int
> > > *data pointer rather than int type).
> > > 
> > > Mike
> > > 
> > 
> > I am sending below patch as per your suggestion. Does it look
> > near to what you have in mind?
> 
> Yes, it does.. just one nit I noticed inlined below.
> 
> > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> > index 350cf0451456..8d89acc8b8c2 100644
> > --- a/drivers/md/dm-table.c
> > +++ b/drivers/md/dm-table.c
> 
> ...
> 
> > @@ -1910,8 +1919,13 @@ void dm_table_set_restrictions(struct dm_table *t,
> > struct request_queue *q,
> >         }
> >         blk_queue_write_cache(q, wc, fua);
> > 
> > -       if (dm_table_supports_dax(t, PAGE_SIZE))
> > +       if (dm_table_supports_dax(t, device_supports_dax, &page_size)) {
> > +
> 
> No need for an empty newline here ^

Sure. Will remove this and send official v12 patchset with the updated patch 4.

Thanks,
Pankaj

> 
> >                 blk_queue_flag_set(QUEUE_FLAG_DAX, q);
> > +               if (dm_table_supports_dax(t, device_synchronous, NULL))
> > +                       set_dax_synchronous(t->md->dax_dev);
> > +       }
> >         else
> >                 blk_queue_flag_clear(QUEUE_FLAG_DAX, q);
> > 
> 
> Thanks,
> Mike
> 
>

Patch
diff mbox series

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 350cf0451456..c5160d846fe6 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -890,10 +890,17 @@  static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
 			start, len);
 }
 
+static int device_synchronous(struct dm_target *ti, struct dm_dev *dev,
+				       sector_t start, sector_t len, void *data)
+{
+	return dax_synchronous(dev->dax_dev);
+}
+
 bool dm_table_supports_dax(struct dm_table *t, int blocksize)
 {
 	struct dm_target *ti;
 	unsigned i;
+	bool dax_sync = true;
 
 	/* Ensure that all targets support DAX. */
 	for (i = 0; i < dm_table_get_num_targets(t); i++) {
@@ -906,7 +913,14 @@  bool dm_table_supports_dax(struct dm_table *t, int blocksize)
 		    !ti->type->iterate_devices(ti, device_supports_dax,
 			    &blocksize))
 			return false;
+
+		/* Check devices support synchronous DAX */
+		if (dax_sync &&
+		    !ti->type->iterate_devices(ti, device_synchronous, NULL))
+			dax_sync = false;
 	}
+	if (dax_sync)
+		set_dax_synchronous(t->md->dax_dev);
 
 	return true;
 }