dm thin: commit before gathering status

Commit outstanding metadata before returning the status for a dm thin
pool so that the numbers reported are as up-to-date as possible.

The commit is not performed if the device is suspended or if
the DM_NOFLUSH_FLAG is supplied by userspace and passed to the target
through a new 'status_flags' parameter in the target's dm_status_fn.

The userspace dmsetup tool will support the --noflush flag with the
'dmsetup status' and 'dmsetup wait' commands from version 1.02.76
onwards.

Tested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

13 files changed, 29 insertions, 16 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 00a25ab987c9..664743d6a6cd 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1733,7 +1733,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
 }
 
 static int crypt_status(struct dm_target *ti, status_type_t type,
-                        char *result, unsigned int maxlen)
+                        unsigned status_flags, char *result, unsigned maxlen)
 {
         struct crypt_config *cc = ti->private;
         unsigned int sz = 0;
diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index 2dc22dddb2ae..f53846f9ab50 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -295,7 +295,7 @@ static int delay_map(struct dm_target *ti, struct bio *bio,
 }
 
 static int delay_status(struct dm_target *ti, status_type_t type,
-                        char *result, unsigned maxlen)
+                        unsigned status_flags, char *result, unsigned maxlen)
 {
         struct delay_c *dc = ti->private;
         int sz = 0;
diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index ac49c01f1a44..cc15543a6ad7 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -333,7 +333,7 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 }
 
 static int flakey_status(struct dm_target *ti, status_type_t type,
-                         char *result, unsigned int maxlen)
+                         unsigned status_flags, char *result, unsigned maxlen)
 {
         unsigned sz = 0;
         struct flakey_c *fc = ti->private;
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index a1a3e6df17b8..afd95986d099 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1054,6 +1054,7 @@ static void retrieve_status(struct dm_table *table,
         char *outbuf, *outptr;
         status_type_t type;
         size_t remaining, len, used = 0;
+        unsigned status_flags = 0;
 
         outptr = outbuf = get_result_buffer(param, param_size, &len);
 
@@ -1090,7 +1091,9 @@ static void retrieve_status(struct dm_table *table,
 
                 /* Get the status/table string from the target driver */
                 if (ti->type->status) {
-                        if (ti->type->status(ti, type, outptr, remaining)) {
+                        if (param->flags & DM_NOFLUSH_FLAG)
+                                status_flags |= DM_STATUS_NOFLUSH_FLAG;
+                        if (ti->type->status(ti, type, status_flags, outptr, remaining)) {
                                 param->flags |= DM_BUFFER_FULL_FLAG;
                                 break;
                         }
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 3639eeab6042..1bf19a93eef0 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -96,7 +96,7 @@ static int linear_map(struct dm_target *ti, struct bio *bio,
 }
 
 static int linear_status(struct dm_target *ti, status_type_t type,
-                         char *result, unsigned int maxlen)
+                         unsigned status_flags, char *result, unsigned maxlen)
 {
         struct linear_c *lc = (struct linear_c *) ti->private;
 
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 8a3b2d53f81b..d8abb90a6c2f 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1378,7 +1378,7 @@ static void multipath_resume(struct dm_target *ti)
  *      num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
  */
 static int multipath_status(struct dm_target *ti, status_type_t type,
-                            char *result, unsigned int maxlen)
+                            unsigned status_flags, char *result, unsigned maxlen)
 {
         int sz = 0;
         unsigned long flags;
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index f4275a8e860c..f2f29c526544 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1081,7 +1081,7 @@ static int raid_map(struct dm_target *ti, struct bio *bio, union map_info *map_c
 }
 
 static int raid_status(struct dm_target *ti, status_type_t type,
-                       char *result, unsigned maxlen)
+                       unsigned status_flags, char *result, unsigned maxlen)
 {
         struct raid_set *rs = ti->private;
         unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 596a3a1164a7..bc5ddba8045b 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1367,7 +1367,7 @@ static char device_status_char(struct mirror *m)
 
 
 static int mirror_status(struct dm_target *ti, status_type_t type,
-                         char *result, unsigned int maxlen)
+                         unsigned status_flags, char *result, unsigned maxlen)
 {
         unsigned int m, sz = 0;
         struct mirror_set *ms = (struct mirror_set *) ti->private;
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 6c0f3e33923a..a143921feaf6 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1849,7 +1849,7 @@ static void snapshot_merge_resume(struct dm_target *ti)
 }
 
 static int snapshot_status(struct dm_target *ti, status_type_t type,
-                           char *result, unsigned int maxlen)
+                           unsigned status_flags, char *result, unsigned maxlen)
 {
         unsigned sz = 0;
         struct dm_snapshot *snap = ti->private;
@@ -2151,8 +2151,8 @@ static void origin_resume(struct dm_target *ti)
         ti->max_io_len = get_origin_minimum_chunksize(dev->bdev);
 }
 
-static int origin_status(struct dm_target *ti, status_type_t type, char *result,
-                         unsigned int maxlen)
+static int origin_status(struct dm_target *ti, status_type_t type,
+                         unsigned status_flags, char *result, unsigned maxlen)
 {
         struct dm_dev *dev = ti->private;
 
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 9e8f4cc63d6c..a087bf2a8d66 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -311,8 +311,8 @@ static int stripe_map(struct dm_target *ti, struct bio *bio,
  *
  */
 
-static int stripe_status(struct dm_target *ti,
-                         status_type_t type, char *result, unsigned int maxlen)
+static int stripe_status(struct dm_target *ti, status_type_t type,
+                         unsigned status_flags, char *result, unsigned maxlen)
 {
         struct stripe_c *sc = (struct stripe_c *) ti->private;
         char buffer[sc->stripes + 1];
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 087e9b34d290..af1fc3b2c2ad 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -5,6 +5,7 @@
  */
 
 #include "dm-thin-metadata.h"
+#include "dm.h"
 
 #include <linux/device-mapper.h>
 #include <linux/dm-io.h>
@@ -2619,7 +2620,7 @@ static void emit_flags(struct pool_features *pf, char *result,
  *    <used data sectors>/<total data sectors> <held metadata root>
  */
 static int pool_status(struct dm_target *ti, status_type_t type,
-                       char *result, unsigned maxlen)
+                       unsigned status_flags, char *result, unsigned maxlen)
 {
         int r;
         unsigned sz = 0;
@@ -2641,6 +2642,10 @@ static int pool_status(struct dm_target *ti, status_type_t type,
                         break;
                 }
 
+                /* Commit to ensure statistics aren't out-of-date */
+                if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
+                        (void) commit_or_fallback(pool);
+
                 r = dm_pool_get_metadata_transaction_id(pool->pmd,
                                                         &transaction_id);
                 if (r)
@@ -2968,7 +2973,7 @@ static void thin_postsuspend(struct dm_target *ti)
  * <nr mapped sectors> <highest mapped sector>
  */
 static int thin_status(struct dm_target *ti, status_type_t type,
-                       char *result, unsigned maxlen)
+                       unsigned status_flags, char *result, unsigned maxlen)
 {
         int r;
         ssize_t sz = 0;
diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
index fa365d39b612..254d19268ad2 100644
--- a/drivers/md/dm-verity.c
+++ b/drivers/md/dm-verity.c
@@ -515,7 +515,7 @@ static int verity_map(struct dm_target *ti, struct bio *bio,
  * Status: V (valid) or C (corruption found)
  */
 static int verity_status(struct dm_target *ti, status_type_t type,
-                         char *result, unsigned maxlen)
+                         unsigned status_flags, char *result, unsigned maxlen)
 {
         struct dm_verity *v = ti->private;
         unsigned sz = 0;
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index b7dacd59d8d7..52eef493d266 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -23,6 +23,11 @@
 #define DM_SUSPEND_NOFLUSH_FLAG         (1 << 1)
 
 /*
+ * Status feature flags
+ */
+#define DM_STATUS_NOFLUSH_FLAG          (1 << 0)
+
+/*
  * Type of table and mapped_device's mempool
  */
 #define DM_TYPE_NONE            0