path: root/drivers/md/dm-thin-metadata.h
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2012-06-02 17:39:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-06-02 17:39:40 -0700
commit912afc3616b94c5c4af584972c7f5903b53cf15a (patch)
tree3edd4596fe53ce5bc8224b1cccd5d34dcac040a7 /drivers/md/dm-thin-metadata.h
parent4fc3acf2918fa158dc651a0c824a23944e956919 (diff)
parentcc8394d86f045b86ff303d3c9e4ce47d97148951 (diff)
Merge tag 'dm-3.5-changes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm
Pull device-mapper updates from Alasdair G Kergon: "Improve multipath's retrying mechanism in some defined circumstances and provide a simple reserve/release mechanism for userspace tools to access thin provisioning metadata while the pool is in use." * tag 'dm-3.5-changes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: dm thin: provide userspace access to pool metadata dm thin: use slab mempools dm mpath: allow ioctls to trigger pg init dm mpath: delay retry of bypassed pg dm mpath: reduce size of struct multipath
Diffstat (limited to 'drivers/md/dm-thin-metadata.h')
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h
index ed4725e67c96..b88918ccdaf6 100644
--- a/drivers/md/dm-thin-metadata.h
+++ b/drivers/md/dm-thin-metadata.h
@@ -90,11 +90,18 @@ int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
* Hold/get root for userspace transaction.
+ *
+ * The metadata snapshot is a copy of the current superblock (minus the
+ * space maps). Userland can access the data structures for READ
+ * operations only. A small performance hit is incurred by providing this
+ * copy of the metadata to userland due to extra copy-on-write operations
+ * on the metadata nodes. Release this as soon as you finish with it.
-int dm_pool_hold_metadata_root(struct dm_pool_metadata *pmd);
+int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
+int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
-int dm_pool_get_held_metadata_root(struct dm_pool_metadata *pmd,
- dm_block_t *result);
+int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
+ dm_block_t *result);
* Actions on a single virtual device.