Merge tag 'dm-3.14-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device-mapper changes from Mike Snitzer:
 "A lot of attention was paid to improving the thin-provisioning
  target's handling of metadata operation failures and running out of
  space.  A new 'error_if_no_space' feature was added to allow users to
  error IOs rather than queue them when either the data or metadata
  space is exhausted.

  Additional fixes/features include:
   - a few fixes to properly support thin metadata device resizing
   - a solution for reliably waiting for a DM device's embedded kobject
     to be released before destroying the device
   - old dm-snapshot is updated to use the dm-bufio interface to take
     advantage of readahead capabilities that improve snapshot
     activation
   - new dm-cache target tunables to control how quickly data is
     promoted to the cache (fast) device
   - improved write efficiency of cluster mirror target by combining
     userspace flush and mark requests"

* tag 'dm-3.14-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (35 commits)
  dm log userspace: allow mark requests to piggyback on flush requests
  dm space map metadata: fix bug in resizing of thin metadata
  dm cache: add policy name to status output
  dm thin: fix pool feature parsing
  dm sysfs: fix a module unload race
  dm snapshot: use dm-bufio prefetch
  dm snapshot: use dm-bufio
  dm snapshot: prepare for switch to using dm-bufio
  dm snapshot: use GFP_KERNEL when initializing exceptions
  dm cache: add block sizes and total cache blocks to status output
  dm btree: add dm_btree_find_lowest_key
  dm space map metadata: fix extending the space map
  dm space map common: make sure new space is used during extend
  dm: wait until embedded kobject is released before destroying a device
  dm: remove pointless kobject comparison in dm_get_from_kobject
  dm snapshot: call destroy_work_on_stack() to pair with INIT_WORK_ONSTACK()
  dm cache policy mq: introduce three promotion threshold tunables
  dm cache policy mq: use list_del_init instead of list_del + INIT_LIST_HEAD
  dm thin: fix set_pool_mode exposed pool operation races
  dm thin: eliminate the no_free_space flag
  ...

3 files changed, 50 insertions, 24 deletions

diff --git a/Documentation/device-mapper/cache-policies.txt b/Documentation/device-mapper/cache-policies.txt
index df52a849957f..66c2774c0c64 100644
--- a/Documentation/device-mapper/cache-policies.txt
+++ b/Documentation/device-mapper/cache-policies.txt
@@ -40,8 +40,11 @@ on hit count on entry. The policy aims to take different cache miss
 costs into account and to adjust to varying load patterns automatically.
 
 Message and constructor argument pairs are:
-	'sequential_threshold <#nr_sequential_ios>' and
-	'random_threshold <#nr_random_ios>'.
+	'sequential_threshold <#nr_sequential_ios>'
+	'random_threshold <#nr_random_ios>'
+	'read_promote_adjustment <value>'
+	'write_promote_adjustment <value>'
+	'discard_promote_adjustment <value>'
 
 The sequential threshold indicates the number of contiguous I/Os
 required before a stream is treated as sequential.  The random threshold
@@ -55,6 +58,15 @@ since spindles tend to have good bandwidth. The io_tracker counts
 contiguous I/Os to try to spot when the io is in one of these sequential
 modes.
 
+Internally the mq policy maintains a promotion threshold variable.  If
+the hit count of a block not in the cache goes above this threshold it
+gets promoted to the cache.  The read, write and discard promote adjustment
+tunables allow you to tweak the promotion threshold by adding a small
+value based on the io type.  They default to 4, 8 and 1 respectively.
+If you're trying to quickly warm a new cache device you may wish to
+reduce these to encourage promotion.  Remember to switch them back to
+their defaults after the cache fills though.
+
 cleaner
 -------
 
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt
index 719320b5ed3f..e6b72d355151 100644
--- a/Documentation/device-mapper/cache.txt
+++ b/Documentation/device-mapper/cache.txt
@@ -217,36 +217,43 @@ the characteristics of a specific policy, always request it by name.
 Status
 ------
 
-<#used metadata blocks>/<#total metadata blocks> <#read hits> <#read misses>
-<#write hits> <#write misses> <#demotions> <#promotions> <#blocks in cache>
-<#dirty> <#features> <features>* <#core args> <core args>* <#policy args>
-<policy args>*
-
-#used metadata blocks    : Number of metadata blocks used
-#total metadata blocks   : Total number of metadata blocks
-#read hits               : Number of times a READ bio has been mapped
+<metadata block size> <#used metadata blocks>/<#total metadata blocks>
+<cache block size> <#used cache blocks>/<#total cache blocks>
+<#read hits> <#read misses> <#write hits> <#write misses>
+<#demotions> <#promotions> <#dirty> <#features> <features>*
+<#core args> <core args>* <policy name> <#policy args> <policy args>*
+
+metadata block size	 : Fixed block size for each metadata block in
+			     sectors
+#used metadata blocks	 : Number of metadata blocks used
+#total metadata blocks	 : Total number of metadata blocks
+cache block size	 : Configurable block size for the cache device
+			     in sectors
+#used cache blocks	 : Number of blocks resident in the cache
+#total cache blocks	 : Total number of cache blocks
+#read hits		 : Number of times a READ bio has been mapped
 			     to the cache
-#read misses             : Number of times a READ bio has been mapped
+#read misses		 : Number of times a READ bio has been mapped
 			     to the origin
-#write hits              : Number of times a WRITE bio has been mapped
+#write hits		 : Number of times a WRITE bio has been mapped
 			     to the cache
-#write misses            : Number of times a WRITE bio has been
+#write misses		 : Number of times a WRITE bio has been
 			     mapped to the origin
-#demotions               : Number of times a block has been removed
+#demotions		 : Number of times a block has been removed
 			     from the cache
-#promotions              : Number of times a block has been moved to
+#promotions		 : Number of times a block has been moved to
 			     the cache
-#blocks in cache         : Number of blocks resident in the cache
-#dirty                   : Number of blocks in the cache that differ
+#dirty			 : Number of blocks in the cache that differ
 			     from the origin
-#feature args            : Number of feature args to follow
-feature args             : 'writethrough' (optional)
-#core args               : Number of core arguments (must be even)
-core args                : Key/value pairs for tuning the core
+#feature args		 : Number of feature args to follow
+feature args		 : 'writethrough' (optional)
+#core args		 : Number of core arguments (must be even)
+core args		 : Key/value pairs for tuning the core
 			     e.g. migration_threshold
-#policy args             : Number of policy arguments to follow (must be even)
-policy args              : Key/value pairs
-			     e.g. 'sequential_threshold 1024
+policy name		 : Name of the policy
+#policy args		 : Number of policy arguments to follow (must be even)
+policy args		 : Key/value pairs
+			     e.g. sequential_threshold
 
 Messages
 --------
diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt
index 50c44cf79b0e..8a7a3d46e0da 100644
--- a/Documentation/device-mapper/thin-provisioning.txt
+++ b/Documentation/device-mapper/thin-provisioning.txt
@@ -235,6 +235,8 @@ i) Constructor
       read_only: Don't allow any changes to be made to the pool
 		 metadata.
 
+      error_if_no_space: Error IOs, instead of queueing, if no space.
+
     Data block size must be between 64KB (128 sectors) and 1GB
     (2097152 sectors) inclusive.
 
@@ -276,6 +278,11 @@ ii) Status
 	contain the string 'Fail'.  The userspace recovery tools
 	should then be used.
 
+    error_if_no_space|queue_if_no_space
+	If the pool runs out of data or metadata space, the pool will
+	either queue or error the IO destined to the data device.  The
+	default is to queue the IO until more space is added.
+
 iii) Messages
 
     create_thin <dev id>