linux/drivers/md/persistent-data, branch v3.12

dm space map: optimise sm_ll_dec and sm_ll_inc

2013-08-23T13:02:14Z

Prior to this patch these methods did a lookup followed by an insert. Instead they now call a common mutate function that adjusts the value according to a callback function. This avoids traversing the data structures twice and hence improves performance. Also factor out sm_ll_lookup_big_ref_count() for use by both sm_ll_lookup() and sm_ll_mutate(). Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm btree: prefetch child nodes when walking tree for a dm_btree_del

2013-08-23T13:02:14Z

dm-btree now takes advantage of dm-bufio's ability to prefetch data via dm_bm_prefetch(). Prior to this change many btree node visits were causing a synchronous read. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm btree: use pop_frame in dm_btree_del to cleanup code

2013-08-23T13:02:14Z

Remove a visited leaf straight away from the stack, rather than marking all it's children as visited and letting it get removed on the next iteration. May also offer a micro optimisation in dm_btree_del. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm persistent metadata: add space map threshold callback

2013-05-10T13:37:20Z

Add a threshold callback to dm persistent data space maps. Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon

dm persistent data: add threshold callback to space map

2013-05-10T13:37:20Z

Add a threshold callback function to the persistent data space map interface for a subsequent patch to use. dm-thin and dm-cache are interested in knowing when they're getting low on metadata or data blocks. This patch introduces a new method for registering a callback against a threshold. Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon

dm persistent data: support space map resizing

2013-05-10T13:37:19Z

Support extending a dm persistent data metadata space map. The extend itself is implemented by switching back to the boostrap allocator and pointing to the new space. The extra bitmap indexes are then allocated from the new space, and finally we switch back to the proper space map ops and tweak the reference counts. Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon

dm persistent data: fix error message typos

2013-05-10T13:37:17Z

Fix some typos in dm-space-map-metadata.c error messages. Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon

dm thin: fix discard corruption

2013-03-20T17:21:24Z

Fix a bug in dm_btree_remove that could leave leaf values with incorrect reference counts. The effect of this was that removal of a shared block could result in the space maps thinking the block was no longer used. More concretely, if you have a thin device and a snapshot of it, sending a discard to a shared region of the thin could corrupt the snapshot. Thinp uses a 2-level nested btree to store it's mappings. This first level is indexed by thin device, and the second level by logical block. Often when we're removing an entry in this mapping tree we need to rebalance nodes, which can involve shadowing them, possibly creating a copy if the block is shared. If we do create a copy then children of that node need to have their reference counts incremented. In this way reference counts percolate down the tree as shared trees diverge. The rebalance functions were incrementing the children at the appropriate time, but they were always assuming the children were internal nodes. This meant the leaf values (in our case packed block/flags entries) were not being incremented. Cc: stable@vger.kernel.org Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon

dm: add cache target

2013-03-01T22:45:51Z

Add a target that allows a fast device such as an SSD to be used as a cache for a slower device such as a disk. A plug-in architecture was chosen so that the decisions about which data to migrate and when are delegated to interchangeable tunable policy modules. The first general purpose module we have developed, called "mq" (multiqueue), follows in the next patch. Other modules are under development. Signed-off-by: Joe Thornber Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm persistent data: add bitset

2013-03-01T22:45:51Z

Add a persistent bitset as a wrapper around dm-array. Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon