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author | Alasdair G Kergon <agk@redhat.com> | 2011-10-31 20:19:00 +0000 |
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committer | Alasdair G Kergon <agk@redhat.com> | 2011-10-31 20:19:00 +0000 |
commit | 3791e2fc0e4b40d4188e79b0a99bfa6bce714a10 (patch) | |
tree | 2dc67f0593e1cb1f3dc07ff9883a03fe9edb4b2a /include/linux/device-mapper.h | |
parent | 7f06965390e4a10fb6906c886324bfd0a96961be (diff) | |
download | linux-stable-3791e2fc0e4b40d4188e79b0a99bfa6bce714a10.tar.gz linux-stable-3791e2fc0e4b40d4188e79b0a99bfa6bce714a10.tar.bz2 linux-stable-3791e2fc0e4b40d4188e79b0a99bfa6bce714a10.zip |
dm table: add singleton feature
Introduce the concept of a singleton table which contains exactly one target.
If a target type sets the DM_TARGET_SINGLETON feature bit device-mapper
will ensure that any table that includes that target contains no others.
The thin provisioning pool target uses this.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'include/linux/device-mapper.h')
-rw-r--r-- | include/linux/device-mapper.h | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 622678ccb5e0..294e78a7fccd 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -128,10 +128,6 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d); * Information about a target type */ -/* - * Target features - */ - struct target_type { uint64_t features; const char *name; @@ -160,6 +156,16 @@ struct target_type { struct list_head list; }; +/* + * Target features + */ + +/* + * Any table that contains an instance of this target must have only one. + */ +#define DM_TARGET_SINGLETON 0x00000001 +#define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON) + struct dm_target { struct dm_table *table; struct target_type *type; |