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Commit cc6cbe14 authored by Alasdair G Kergon's avatar Alasdair G Kergon
Browse files

dm table: add always writeable feature 



Add a target feature flag DM_TARGET_ALWAYS_WRITEABLE to indicate that a target
does not support read-only mode.

The initial implementation of the thin provisioning target uses this.

Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 3791e2fc

drivers/md/dm-table.c

+6 −0
Original line number Diff line number Diff line
@@ -774,6 +774,12 @@ int dm_table_add_target(struct dm_table *t, const char *type, 
		t->singleton = 1;

	}



	if (dm_target_always_writeable(tgt->type) && !(t->mode & FMODE_WRITE)) {

		DMERR("%s: target type %s may not be included in read-only tables",

		      dm_device_name(t->md), type);

		return -EINVAL;

	}



	tgt->table = t;

	tgt->begin = start;

	tgt->len = len;

include/linux/device-mapper.h

+7 −0
Original line number Diff line number Diff line
@@ -166,6 +166,13 @@ struct target_type { 
#define DM_TARGET_SINGLETON		0x00000001

#define dm_target_needs_singleton(type)	((type)->features & DM_TARGET_SINGLETON)



/*

 * Indicates that a target does not support read-only devices.

 */

#define DM_TARGET_ALWAYS_WRITEABLE	0x00000002

#define dm_target_always_writeable(type) \

		((type)->features & DM_TARGET_ALWAYS_WRITEABLE)



struct dm_target {

	struct dm_table *table;

	struct target_type *type;