Merge tag 'for-4.12/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - A major update for DM cache that reduces the latency for deciding
   whether blocks should migrate to/from the cache. The bio-prison-v2
   interface supports this improvement by enabling direct dispatch of
   work to workqueues rather than having to delay the actual work
   dispatch to the DM cache core. So the dm-cache policies are much more
   nimble by being able to drive IO as they see fit. One immediate
   benefit from the improved latency is a cache that should be much more
   adaptive to changing workloads.

 - Add a new DM integrity target that emulates a block device that has
   additional per-sector tags that can be used for storing integrity
   information.

 - Add a new authenticated encryption feature to the DM crypt target
   that builds on the capabilities provided by the DM integrity target.

 - Add MD interface for switching the raid4/5/6 journal mode and update
   the DM raid target to use it to enable aid4/5/6 journal write-back
   support.

 - Switch the DM verity target over to using the asynchronous hash
   crypto API (this helps work better with architectures that have
   access to off-CPU algorithm providers, which should reduce CPU
   utilization).

 - Various request-based DM and DM multipath fixes and improvements from
   Bart and Christoph.

 - A DM thinp target fix for a bio structure leak that occurs for each
   discard IFF discard passdown is enabled.

 - A fix for a possible deadlock in DM bufio and a fix to re-check the
   new buffer allocation watermark in the face of competing admin
   changes to the 'max_cache_size_bytes' tunable.

 - A couple DM core cleanups.

* tag 'for-4.12/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (50 commits)
  dm bufio: check new buffer allocation watermark every 30 seconds
  dm bufio: avoid a possible ABBA deadlock
  dm mpath: make it easier to detect unintended I/O request flushes
  dm mpath: cleanup QUEUE_IF_NO_PATH bit manipulation by introducing assign_bit()
  dm mpath: micro-optimize the hot path relative to MPATHF_QUEUE_IF_NO_PATH
  dm: introduce enum dm_queue_mode to cleanup related code
  dm mpath: verify __pg_init_all_paths locking assumptions at runtime
  dm: verify suspend_locking assumptions at runtime
  dm block manager: remove an unused argument from dm_block_manager_create()
  dm rq: check blk_mq_register_dev() return value in dm_mq_init_request_queue()
  dm mpath: delay requeuing while path initialization is in progress
  dm mpath: avoid that path removal can trigger an infinite loop
  dm mpath: split and rename activate_path() to prepare for its expanded use
  dm ioctl: prevent stack leak in dm ioctl call
  dm integrity: use previously calculated log2 of sectors_per_block
  dm integrity: use hex2bin instead of open-coded variant
  dm crypt: replace custom implementation of hex2bin()
  dm crypt: remove obsolete references to per-CPU state
  dm verity: switch to using asynchronous hash crypto API
  dm crypt: use WQ_HIGHPRI for the IO and crypt workqueues
  ...

1 files changed, 34 insertions, 28 deletions

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index b6194e082e48..26ba09282e7c 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -54,16 +54,6 @@
  */
 #define R5L_POOL_SIZE	4
 
-/*
- * r5c journal modes of the array: write-back or write-through.
- * write-through mode has identical behavior as existing log only
- * implementation.
- */
-enum r5c_journal_mode {
-	R5C_JOURNAL_MODE_WRITE_THROUGH = 0,
-	R5C_JOURNAL_MODE_WRITE_BACK = 1,
-};
-
 static char *r5c_journal_mode_str[] = {"write-through",
 				       "write-back"};
 /*
@@ -2526,40 +2516,56 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
 	return ret;
 }
 
-static ssize_t r5c_journal_mode_store(struct mddev *mddev,
-				      const char *page, size_t length)
+/*
+ * Set journal cache mode on @mddev (external API initially needed by dm-raid).
+ *
+ * @mode as defined in 'enum r5c_journal_mode'.
+ *
+ */
+int r5c_journal_mode_set(struct mddev *mddev, int mode)
 {
 	struct r5conf *conf = mddev->private;
 	struct r5l_log *log = conf->log;
-	int val = -1, i;
-	int len = length;
 
 	if (!log)
 		return -ENODEV;
 
-	if (len && page[len - 1] == '\n')
-		len -= 1;
-	for (i = 0; i < ARRAY_SIZE(r5c_journal_mode_str); i++)
-		if (strlen(r5c_journal_mode_str[i]) == len &&
-		    strncmp(page, r5c_journal_mode_str[i], len) == 0) {
-			val = i;
-			break;
-		}
-	if (val < R5C_JOURNAL_MODE_WRITE_THROUGH ||
-	    val > R5C_JOURNAL_MODE_WRITE_BACK)
+	if (mode < R5C_JOURNAL_MODE_WRITE_THROUGH ||
+	    mode > R5C_JOURNAL_MODE_WRITE_BACK)
 		return -EINVAL;
 
 	if (raid5_calc_degraded(conf) > 0 &&
-	    val == R5C_JOURNAL_MODE_WRITE_BACK)
+	    mode == R5C_JOURNAL_MODE_WRITE_BACK)
 		return -EINVAL;
 
 	mddev_suspend(mddev);
-	conf->log->r5c_journal_mode = val;
+	conf->log->r5c_journal_mode = mode;
 	mddev_resume(mddev);
 
 	pr_debug("md/raid:%s: setting r5c cache mode to %d: %s\n",
-		 mdname(mddev), val, r5c_journal_mode_str[val]);
-	return length;
+		 mdname(mddev), mode, r5c_journal_mode_str[mode]);
+	return 0;
+}
+EXPORT_SYMBOL(r5c_journal_mode_set);
+
+static ssize_t r5c_journal_mode_store(struct mddev *mddev,
+				      const char *page, size_t length)
+{
+	int mode = ARRAY_SIZE(r5c_journal_mode_str);
+	size_t len = length;
+
+	if (len < 2)
+		return -EINVAL;
+
+	if (page[len - 1] == '\n')
+		len--;
+
+	while (mode--)
+		if (strlen(r5c_journal_mode_str[mode]) == len &&
+		    !strncmp(page, r5c_journal_mode_str[mode], len))
+			break;
+
+	return r5c_journal_mode_set(mddev, mode) ?: length;
 }
 
 struct md_sysfs_entry