Merge tag 'dm-3.6-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull device-mapper updates from Alasdair G Kergon:
- Flip the thin target into new read-only or failed modes if errors
  are detected;
- Handle chunk sizes that are not powers of two in the snapshot and
  thin targets;
- Provide a way for userspace to avoid replacing an already-loaded
  multipath hardware handler while booting;
- Reduce dm_thin_endio_hook slab size to avoid allocation failures;
- Numerous small changes and cleanups to the code.

* tag 'dm-3.6-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: (63 commits)
  dm thin: commit before gathering status
  dm thin: add read only and fail io modes
  dm thin metadata: introduce dm_pool_abort_metadata
  dm thin metadata: introduce dm_pool_metadata_set_read_only
  dm persistent data: introduce dm_bm_set_read_only
  dm thin: reduce number of metadata commits
  dm thin metadata: add dm_thin_changed_this_transaction
  dm thin metadata: add format option to dm_pool_metadata_open
  dm thin metadata: tidy up open and format error paths
  dm thin metadata: only check incompat features on open
  dm thin metadata: remove duplicate pmd initialisation
  dm thin metadata: remove create parameter from __create_persistent_data_objects
  dm thin metadata: move __superblock_all_zeroes to __open_or_format_metadata
  dm thin metadata: remove nr_blocks arg from __create_persistent_data_objects
  dm thin metadata: split __open or format metadata
  dm thin metadata: use struct dm_pool_metadata members in __open_or_format_metadata
  dm thin metadata: zero unused superblock uuid
  dm thin metadata: lift __begin_transaction out of __write_initial_superblock
  dm thin metadata: move dm_commit_pool_metadata into __write_initial_superblock
  dm thin metadata: factor out __write_initial_superblock
  ...

2 files changed, 26 insertions, 5 deletions

diff --git a/Documentation/device-mapper/striped.txt b/Documentation/device-mapper/striped.txt
index f34d3236b9d..45f3b91ea4c 100644
--- a/Documentation/device-mapper/striped.txt
+++ b/Documentation/device-mapper/striped.txt
@@ -9,15 +9,14 @@ devices in parallel.
 
 Parameters: <num devs> <chunk size> [<dev path> <offset>]+
     <num devs>: Number of underlying devices.
-    <chunk size>: Size of each chunk of data. Must be a power-of-2 and at
-                  least as large as the system's PAGE_SIZE.
+    <chunk size>: Size of each chunk of data. Must be at least as
+                  large as the system's PAGE_SIZE.
     <dev path>: Full pathname to the underlying block-device, or a
                 "major:minor" device-number.
     <offset>: Starting sector within the device.
 
 One or more underlying devices can be specified. The striped device size must
-be a multiple of the chunk size and a multiple of the number of underlying
-devices.
+be a multiple of the chunk size multiplied by the number of underlying devices.
 
 
 Example scripts
diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt
index f5cfc62b7ad..30b8b83bd33 100644
--- a/Documentation/device-mapper/thin-provisioning.txt
+++ b/Documentation/device-mapper/thin-provisioning.txt
@@ -231,6 +231,9 @@ i) Constructor
       no_discard_passdown: Don't pass discards down to the underlying
                            data device, but just remove the mapping.
 
+      read_only: Don't allow any changes to be made to the pool
+                 metadata.
+
     Data block size must be between 64KB (128 sectors) and 1GB
     (2097152 sectors) inclusive.
 
@@ -239,7 +242,7 @@ ii) Status
 
     <transaction id> <used metadata blocks>/<total metadata blocks>
     <used data blocks>/<total data blocks> <held metadata root>
-
+    [no_]discard_passdown ro|rw
 
     transaction id:
         A 64-bit number used by userspace to help synchronise with metadata
@@ -257,6 +260,21 @@ ii) Status
         held root.  This feature is not yet implemented so '-' is
         always returned.
 
+    discard_passdown|no_discard_passdown
+        Whether or not discards are actually being passed down to the
+        underlying device.  When this is enabled when loading the table,
+        it can get disabled if the underlying device doesn't support it.
+
+    ro|rw
+        If the pool encounters certain types of device failures it will
+        drop into a read-only metadata mode in which no changes to
+        the pool metadata (like allocating new blocks) are permitted.
+
+        In serious cases where even a read-only mode is deemed unsafe
+        no further I/O will be permitted and the status will just
+        contain the string 'Fail'.  The userspace recovery tools
+        should then be used.
+
 iii) Messages
 
     create_thin <dev id>
@@ -329,3 +347,7 @@ regain some space then send the 'trim' message to the pool.
 ii) Status
 
      <nr mapped sectors> <highest mapped sector>
+
+        If the pool has encountered device errors and failed, the status
+        will just contain the string 'Fail'.  The userspace recovery
+        tools should then be used.