[PATCH 12/15] dm: add exports

[PATCH 12/15] dm: add exports

[Alasdair G Kergon]

Export core device-mapper functions for manipulating mapped devices
and their tables and move them to <linux/device-mapper.h>.

Protect the contents of device-mapper.h with ifdef __KERNEL__ FWIW,
and throw in a few formatting clean-ups and extra comments.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>

Index: linux-2.6.17/drivers/md/dm.c
===================================================================
--- linux-2.6.17.orig/drivers/md/dm.c	2006-06-21 18:32:21.000000000 +0100
+++ linux-2.6.17/drivers/md/dm.c	2006-06-21 18:32:25.000000000 +0100
@@ -51,10 +51,11 @@ struct target_io {
 
 union map_info *dm_get_mapinfo(struct bio *bio)
 {
-        if (bio && bio->bi_private)
-                return &((struct target_io *)bio->bi_private)->info;
-        return NULL;
+	if (bio && bio->bi_private)
+		return &((struct target_io *)bio->bi_private)->info;
+	return NULL;
 }
+EXPORT_SYMBOL_GPL(dm_get_mapinfo);
 
 #define MINOR_ALLOCED ((void *)-1)
 
@@ -382,6 +383,7 @@ struct dm_table *dm_get_table(struct map
 
 	return t;
 }
+EXPORT_SYMBOL_GPL(dm_get_table);
 
 /*
  * Get the geometry associated with a dm device
@@ -392,6 +394,7 @@ int dm_get_geometry(struct mapped_device
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(dm_get_geometry);
 
 /*
  * Set the geometry of a device.
@@ -409,6 +412,7 @@ int dm_set_geometry(struct mapped_device
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(dm_set_geometry);
 
 /*-----------------------------------------------------------------
  * CRUD START:
@@ -514,8 +518,8 @@ static void __map_bio(struct dm_target *
 	if (r > 0) {
 		/* the bio has been remapped so dispatch it */
 
-		blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone, 
-				    tio->io->bio->bi_bdev->bd_dev, sector, 
+		blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
+				    tio->io->bio->bi_bdev->bd_dev, sector,
 				    clone->bi_sector);
 
 		generic_make_request(clone);
@@ -1068,6 +1072,7 @@ int dm_create(int minor, struct mapped_d
 	*result = md;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(dm_create);
 
 static struct mapped_device *dm_find_md(dev_t dev)
 {
@@ -1082,7 +1087,7 @@ static struct mapped_device *dm_find_md(
 	md = idr_find(&_minor_idr, minor);
 	if (md && (md == MINOR_ALLOCED ||
 		   (dm_disk(md)->first_minor != minor) ||
-	           test_bit(DMF_FREEING, &md->flags))) {
+		   test_bit(DMF_FREEING, &md->flags))) {
 		md = NULL;
 		goto out;
 	}
@@ -1102,16 +1107,19 @@ struct mapped_device *dm_get_md(dev_t de
 
 	return md;
 }
+EXPORT_SYMBOL_GPL(dm_get_md);
 
 void *dm_get_mdptr(struct mapped_device *md)
 {
 	return md->interface_ptr;
 }
+EXPORT_SYMBOL_GPL(dm_get_mdptr);
 
 void dm_set_mdptr(struct mapped_device *md, void *ptr)
 {
 	md->interface_ptr = ptr;
 }
+EXPORT_SYMBOL_GPL(dm_set_mdptr);
 
 void dm_get(struct mapped_device *md)
 {
@@ -1138,6 +1146,7 @@ void dm_put(struct mapped_device *md)
 		free_dev(md);
 	}
 }
+EXPORT_SYMBOL_GPL(dm_put);
 
 /*
  * Process the deferred bios
@@ -1174,6 +1183,7 @@ out:
 	up(&md->suspend_lock);
 	return r;
 }
+EXPORT_SYMBOL_GPL(dm_swap_table);
 
 /*
  * Functions to lock and unlock any filesystem running on the
@@ -1306,6 +1316,7 @@ out:
 	up(&md->suspend_lock);
 	return r;
 }
+EXPORT_SYMBOL_GPL(dm_suspend);
 
 int dm_resume(struct mapped_device *md)
 {
@@ -1347,6 +1358,7 @@ out:
 
 	return r;
 }
+EXPORT_SYMBOL_GPL(dm_resume);
 
 /*-----------------------------------------------------------------
  * Event notification.
@@ -1355,12 +1367,14 @@ uint32_t dm_get_event_nr(struct mapped_d
 {
 	return atomic_read(&md->event_nr);
 }
+EXPORT_SYMBOL_GPL(dm_get_event_nr);
 
 int dm_wait_event(struct mapped_device *md, int event_nr)
 {
 	return wait_event_interruptible(md->eventq,
 			(event_nr != atomic_read(&md->event_nr)));
 }
+EXPORT_SYMBOL_GPL(dm_wait_event);
 
 /*
  * The gendisk is only valid as long as you have a reference
@@ -1370,11 +1384,13 @@ struct gendisk *dm_disk(struct mapped_de
 {
 	return md->disk;
 }
+EXPORT_SYMBOL_GPL(dm_disk);
 
 int dm_suspended(struct mapped_device *md)
 {
 	return test_bit(DMF_SUSPENDED, &md->flags);
 }
+EXPORT_SYMBOL_GPL(dm_suspended);
 
 static struct block_device_operations dm_blk_dops = {
 	.open = dm_blk_open,
@@ -1384,8 +1400,6 @@ static struct block_device_operations dm
 	.owner = THIS_MODULE
 };
 
-EXPORT_SYMBOL(dm_get_mapinfo);
-
 /*
  * module hooks
  */
Index: linux-2.6.17/include/linux/device-mapper.h
===================================================================
--- linux-2.6.17.orig/include/linux/device-mapper.h	2006-06-21 17:45:05.000000000 +0100
+++ linux-2.6.17/include/linux/device-mapper.h	2006-06-21 18:32:25.000000000 +0100
@@ -8,9 +8,12 @@
 #ifndef _LINUX_DEVICE_MAPPER_H
 #define _LINUX_DEVICE_MAPPER_H
 
+#ifdef __KERNEL__
+
 struct dm_target;
 struct dm_table;
 struct dm_dev;
+struct mapped_device;
 
 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
 
@@ -82,7 +85,7 @@ void dm_put_device(struct dm_target *ti,
 struct target_type {
 	const char *name;
 	struct module *module;
-        unsigned version[3];
+	unsigned version[3];
 	dm_ctr_fn ctr;
 	dm_dtr_fn dtr;
 	dm_map_fn map;
@@ -133,4 +136,101 @@ struct dm_target {
 int dm_register_target(struct target_type *t);
 int dm_unregister_target(struct target_type *t);
 
-#endif				/* _LINUX_DEVICE_MAPPER_H */
+
+/*-----------------------------------------------------------------
+ * Functions for creating and manipulating mapped devices.
+ * Drop the reference with dm_put when you finish with the object.
+ *---------------------------------------------------------------*/
+
+/*
+ * DM_ANY_MINOR chooses the next available minor number.
+ */
+#define DM_ANY_MINOR (-1)
+int dm_create(int minor, struct mapped_device **md);
+
+/*
+ * Reference counting for md.
+ */
+struct mapped_device *dm_get_md(dev_t dev);
+void dm_get(struct mapped_device *md);
+void dm_put(struct mapped_device *md);
+
+/*
+ * An arbitrary pointer may be stored alongside a mapped device.
+ */
+void dm_set_mdptr(struct mapped_device *md, void *ptr);
+void *dm_get_mdptr(struct mapped_device *md);
+
+/*
+ * A device can still be used while suspended, but I/O is deferred.
+ */
+int dm_suspend(struct mapped_device *md, int with_lockfs);
+int dm_resume(struct mapped_device *md);
+
+/*
+ * Event functions.
+ */
+uint32_t dm_get_event_nr(struct mapped_device *md);
+int dm_wait_event(struct mapped_device *md, int event_nr);
+
+/*
+ * Info functions.
+ */
+struct gendisk *dm_disk(struct mapped_device *md);
+int dm_suspended(struct mapped_device *md);
+
+/*
+ * Geometry functions.
+ */
+int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
+int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
+
+
+/*-----------------------------------------------------------------
+ * Functions for manipulating device-mapper tables.
+ *---------------------------------------------------------------*/
+
+/*
+ * First create an empty table.
+ */
+int dm_table_create(struct dm_table **result, int mode,
+		    unsigned num_targets, struct mapped_device *md);
+
+/*
+ * Then call this once for each target.
+ */
+int dm_table_add_target(struct dm_table *t, const char *type,
+			sector_t start, sector_t len, char *params);
+
+/*
+ * Finally call this to make the table ready for use.
+ */
+int dm_table_complete(struct dm_table *t);
+
+/*
+ * Table reference counting.
+ */
+struct dm_table *dm_get_table(struct mapped_device *md);
+void dm_table_get(struct dm_table *t);
+void dm_table_put(struct dm_table *t);
+
+/*
+ * Queries
+ */
+sector_t dm_table_get_size(struct dm_table *t);
+unsigned int dm_table_get_num_targets(struct dm_table *t);
+int dm_table_get_mode(struct dm_table *t);
+struct mapped_device *dm_table_get_md(struct dm_table *t);
+
+/*
+ * Trigger an event.
+ */
+void dm_table_event(struct dm_table *t);
+
+/*
+ * The device must be suspended before calling this method.
+ */
+int dm_swap_table(struct mapped_device *md, struct dm_table *t);
+
+#endif	/* __KERNEL__ */
+#endif	/* _LINUX_DEVICE_MAPPER_H */
Index: linux-2.6.17/drivers/md/dm.h
===================================================================
--- linux-2.6.17.orig/drivers/md/dm.h	2006-06-21 18:32:21.000000000 +0100
+++ linux-2.6.17/drivers/md/dm.h	2006-06-21 18:32:25.000000000 +0100
@@ -39,88 +39,16 @@ struct dm_dev {
 };
 
 struct dm_table;
-struct mapped_device;
 
 /*-----------------------------------------------------------------
- * Functions for manipulating a struct mapped_device.
- * Drop the reference with dm_put when you finish with the object.
+ * Internal table functions.
  *---------------------------------------------------------------*/
-
-/*
- * DM_ANY_MINOR allocates any available minor number.
- */
-#define DM_ANY_MINOR (-1)
-int dm_create(int minor, struct mapped_device **md);
-
-void dm_set_mdptr(struct mapped_device *md, void *ptr);
-void *dm_get_mdptr(struct mapped_device *md);
-
-/*
- * Reference counting for md.
- */
-void dm_get(struct mapped_device *md);
-struct mapped_device *dm_get_md(dev_t dev);
-void dm_put(struct mapped_device *md);
-
-/*
- * A device can still be used while suspended, but I/O is deferred.
- */
-int dm_suspend(struct mapped_device *md, int with_lockfs);
-int dm_resume(struct mapped_device *md);
-
-/*
- * The device must be suspended before calling this method.
- */
-int dm_swap_table(struct mapped_device *md, struct dm_table *t);
-
-/*
- * Drop a reference on the table when you've finished with the
- * result.
- */
-struct dm_table *dm_get_table(struct mapped_device *md);
-
-/*
- * Event functions.
- */
-uint32_t dm_get_event_nr(struct mapped_device *md);
-int dm_wait_event(struct mapped_device *md, int event_nr);
-
-/*
- * Info functions.
- */
-struct gendisk *dm_disk(struct mapped_device *md);
-int dm_suspended(struct mapped_device *md);
-
-/*
- * Geometry functions.
- */
-int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
-int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
-
-/*-----------------------------------------------------------------
- * Functions for manipulating a table.  Tables are also reference
- * counted.
- *---------------------------------------------------------------*/
-int dm_table_create(struct dm_table **result, int mode,
-		    unsigned num_targets, struct mapped_device *md);
-
-void dm_table_get(struct dm_table *t);
-void dm_table_put(struct dm_table *t);
-
-int dm_table_add_target(struct dm_table *t, const char *type,
-			sector_t start,	sector_t len, char *params);
-int dm_table_complete(struct dm_table *t);
 void dm_table_event_callback(struct dm_table *t,
 			     void (*fn)(void *), void *context);
-void dm_table_event(struct dm_table *t);
-sector_t dm_table_get_size(struct dm_table *t);
 struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index);
 struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector);
 void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q);
-unsigned int dm_table_get_num_targets(struct dm_table *t);
 struct list_head *dm_table_get_devices(struct dm_table *t);
-int dm_table_get_mode(struct dm_table *t);
-struct mapped_device *dm_table_get_md(struct dm_table *t);
 void dm_table_presuspend_targets(struct dm_table *t);
 void dm_table_postsuspend_targets(struct dm_table *t);
 void dm_table_resume_targets(struct dm_table *t);
@@ -138,7 +66,6 @@ void dm_put_target_type(struct target_ty
 int dm_target_iterate(void (*iter_func)(struct target_type *tt,
 					void *param), void *param);
 
-
 /*-----------------------------------------------------------------
  * Useful inlines.
  *---------------------------------------------------------------*/
Index: linux-2.6.17/drivers/md/dm-table.c
===================================================================
--- linux-2.6.17.orig/drivers/md/dm-table.c	2006-06-21 18:32:19.000000000 +0100
+++ linux-2.6.17/drivers/md/dm-table.c	2006-06-21 18:32:25.000000000 +0100
@@ -236,6 +236,7 @@ int dm_table_create(struct dm_table **re
 	*result = t;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(dm_table_create);
 
 static void free_devices(struct list_head *devices)
 {
@@ -726,6 +727,7 @@ int dm_table_add_target(struct dm_table 
 	dm_put_target_type(tgt->type);
 	return r;
 }
+EXPORT_SYMBOL_GPL(dm_table_add_target);
 
 static int setup_indexes(struct dm_table *t)
 {
@@ -776,6 +778,7 @@ int dm_table_complete(struct dm_table *t
 
 	return r;
 }
+EXPORT_SYMBOL_GPL(dm_table_complete);
 
 static DEFINE_MUTEX(_event_lock);
 void dm_table_event_callback(struct dm_table *t,
@@ -857,6 +860,7 @@ unsigned int dm_table_get_num_targets(st
 {
 	return t->num_targets;
 }
+EXPORT_SYMBOL_GPL(dm_table_get_num_targets);
 
 struct list_head *dm_table_get_devices(struct dm_table *t)
 {

Re: [PATCH 12/15] dm: add exports

[Andrew Morton]

On Wed, 21 Jun 2006 20:36:57 +0100
Alasdair G Kergon <agk@redhat.com> wrote:

> Export core device-mapper functions for manipulating mapped devices
> and their tables and move them to <linux/device-mapper.h>.
> 

Twenty new exports.  What are they all for?

Re: [PATCH 12/15] dm: add exports

[Alasdair G Kergon]

On Wed, Jun 21, 2006 at 09:05:04PM -0700, Andrew Morton wrote:
> Twenty new exports.  What are they all for?

The exports correspond to the functionality available to userspace through
the existing ioctl interface.

Currently, we only offer an ioctl interface for device-mapper and this is
unsuitable for any future in-kernel users wishing to make use of
device-mapper facilities.

Alasdair
-- 
agk@redhat.com

Re: [PATCH 12/15] dm: add exports

[Andrew Morton]

On Thu, 22 Jun 2006 14:51:17 +0100
Alasdair G Kergon <agk@redhat.com> wrote:

> On Wed, Jun 21, 2006 at 09:05:04PM -0700, Andrew Morton wrote:
> > Twenty new exports.  What are they all for?
> 
> The exports correspond to the functionality available to userspace through
> the existing ioctl interface.
> 
> Currently, we only offer an ioctl interface for device-mapper and this is
> unsuitable for any future in-kernel users wishing to make use of
> device-mapper facilities.
> 

Normally we don't export symbols until there's something in-tree which
needs that export.

Occasionally we'll leave a symbol exported when it has no in-tree users,
because it is part of an API which is exported in toto.  But I don't think
that's the case here.

Adding twenty new unused exports is rather a big deal.  Do you have some
new code pending which will use all these?

Re: [PATCH 12/15] dm: add exports

[Alasdair G Kergon]

On Thu, Jun 22, 2006 at 10:03:53AM -0700, Andrew Morton wrote:
> Adding twenty new unused exports is rather a big deal.  Do you have some
> new code pending which will use all these?

No - there's code on the horizon which wants to use a few and so I did this
clean-up exercise to indicate which ones should be used and which ones
shouldn't.  It's no problem delaying the actual exports until they're
specifically requested, but I would at least like to move the definitions
into include/linux so people know they are welcome to use them if they wish.

Alasdair
-- 
agk@redhat.com

Re: [PATCH 12/15] dm: add exports

[Arjan van de Ven]

On Fri, 2006-06-23 at 16:00 +0100, Alasdair G Kergon wrote:
> On Thu, Jun 22, 2006 at 10:03:53AM -0700, Andrew Morton wrote:
> > Adding twenty new unused exports is rather a big deal.  Do you have some
> > new code pending which will use all these?
> 
> No - there's code on the horizon which wants to use a few and so I did this
> clean-up exercise to indicate which ones should be used and which ones
> shouldn't.  It's no problem delaying the actual exports until they're
> specifically requested, but I would at least like to move the definitions
> into include/linux so people know they are welcome to use them if they wish.

the thing is, exports make the kernel bigger (over 100Kb or so total on
just the unused ones), so avoiding unneeded ones as much as possible
would be a good thing.

Re: [PATCH 12/15] dm: add exports

[Christoph Hellwig]

On Fri, Jun 23, 2006 at 04:00:11PM +0100, Alasdair G Kergon wrote:
> On Thu, Jun 22, 2006 at 10:03:53AM -0700, Andrew Morton wrote:
> > Adding twenty new unused exports is rather a big deal.  Do you have some
> > new code pending which will use all these?
> 
> No - there's code on the horizon which wants to use a few and so I did this
> clean-up exercise to indicate which ones should be used and which ones
> shouldn't.  It's no problem delaying the actual exports until they're
> specifically requested, but I would at least like to move the definitions
> into include/linux so people know they are welcome to use them if they wish.

Please dont introduce exports eaarly.  I'm also very curious about what kind
of user you have in the pipeline, calling these functions from kernelspace
seems very wrong to me.

Re: [PATCH 12/15] dm: add exports

[Andrew Morton]

On Fri, 23 Jun 2006 16:33:23 +0100
Christoph Hellwig <hch@infradead.org> wrote:

> On Fri, Jun 23, 2006 at 04:00:11PM +0100, Alasdair G Kergon wrote:
> > On Thu, Jun 22, 2006 at 10:03:53AM -0700, Andrew Morton wrote:
> > > Adding twenty new unused exports is rather a big deal.  Do you have some
> > > new code pending which will use all these?
> > 
> > No - there's code on the horizon which wants to use a few and so I did this
> > clean-up exercise to indicate which ones should be used and which ones
> > shouldn't.  It's no problem delaying the actual exports until they're
> > specifically requested, but I would at least like to move the definitions
> > into include/linux so people know they are welcome to use them if they wish.
> 
> Please dont introduce exports eaarly.  I'm also very curious about what kind
> of user you have in the pipeline, calling these functions from kernelspace
> seems very wrong to me.

So Alasdair, we need to work out what we're going to do about all this.  I
think the current status is:

- hold off on dm-add-exports.patch

- Rework needed on

	dm-support-ioctls-on-mapped-devices.patch
	dm-linear-support-ioctls.patch
	dm-mpath-support-ioctls.patch
	dm-export-blkdev_driver_ioctl.patch

- We're OK with

	dm-mirror-log-sector-size-fix.patch
	dm-mirror-log-refactor-context.patch
	dm-mirror-log-bitset_size-fix.patch
	dm-mirror-log-sync_count-fix.patch
	dm-kcopyd-error-accumulation-fix.patch
	dm-table-split_args-handle-no-input.patch
	dm-consolidate-creation-functions.patch
	dm-create-error-table.patch
	dm-prevent-removal-if-open.patch
	dm-improve-error-message-consistency.patch

Which means going from this:

	dm-support-ioctls-on-mapped-devices.patch
	dm-linear-support-ioctls.patch
	dm-mpath-support-ioctls.patch
	dm-export-blkdev_driver_ioctl.patch
	dm-mirror-log-sector-size-fix.patch
	dm-mirror-log-refactor-context.patch
	dm-mirror-log-bitset_size-fix.patch
	dm-mirror-log-sync_count-fix.patch
	dm-kcopyd-error-accumulation-fix.patch
	dm-table-split_args-handle-no-input.patch
	dm-consolidate-creation-functions.patch
	dm-add-exports.patch
	dm-create-error-table.patch
	dm-prevent-removal-if-open.patch
	dm-improve-error-message-consistency.patch

to this:

	# for 2.6.18:
	dm-mirror-log-sector-size-fix.patch
	dm-mirror-log-refactor-context.patch
	dm-mirror-log-bitset_size-fix.patch
	dm-mirror-log-sync_count-fix.patch
	dm-kcopyd-error-accumulation-fix.patch
	dm-table-split_args-handle-no-input.patch
	dm-consolidate-creation-functions.patch
	dm-create-error-table.patch
	dm-prevent-removal-if-open.patch
	dm-improve-error-message-consistency.patch
	# rework in progress:
	dm-support-ioctls-on-mapped-devices.patch
	dm-linear-support-ioctls.patch
	dm-mpath-support-ioctls.patch
	dm-export-blkdev_driver_ioctl.patch
	# later:
	dm-add-exports.patch

but I'm uncertain if I can just reshuffle them like this, because at least
two of them update the userspace-visible DM version number.

Re: [PATCH 12/15] dm: add exports

[Alasdair G Kergon]

On Fri, Jun 23, 2006 at 02:00:40PM -0700, Andrew Morton wrote:
> but I'm uncertain if I can just reshuffle them like this, because at least
> two of them update the userspace-visible DM version number.

In this instance there's nothing in distributed userspace code relying on the
actual version numbers yet, so it's OK to swap them over if the ioctl patches
are held back:

  dm-prevent-removal-if-open.patch then sets #define DM_VERSION_MINOR 7

  dm-support-ioctls-on-mapped-devices.patch then sets #define DM_VERSION_MINOR 8

(The date in DM_VERSION_EXTRA is for information only - can either leave alone
or set to today's date when edited.)

Alasdair
-- 
agk@redhat.com