dm thin: refactor data dev resize

Refactor device size functions in preparation for similar metadata
device resizing functions.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

2 files changed, 64 insertions, 33 deletions

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 00cee02f8fc9..9452a489ed99 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1645,12 +1645,12 @@ int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
         return r;
 }
 
-static int __resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
+static int __resize_space_map(struct dm_space_map *sm, dm_block_t new_count)
 {
         int r;
         dm_block_t old_count;
 
-        r = dm_sm_get_nr_blocks(pmd->data_sm, &old_count);
+        r = dm_sm_get_nr_blocks(sm, &old_count);
         if (r)
                 return r;
 
@@ -1658,11 +1658,11 @@ static int __resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
                 return 0;
 
         if (new_count < old_count) {
-                DMERR("cannot reduce size of data device");
+                DMERR("cannot reduce size of space map");
                 return -EINVAL;
         }
 
-        return dm_sm_extend(pmd->data_sm, new_count - old_count);
+        return dm_sm_extend(sm, new_count - old_count);
 }
 
 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
@@ -1671,7 +1671,7 @@ int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
 
         down_write(&pmd->root_lock);
         if (!pmd->fail_io)
-                r = __resize_data_dev(pmd, new_count);
+                r = __resize_space_map(pmd->data_sm, new_count);
         up_write(&pmd->root_lock);
 
         return r;
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 004ad1652b73..111c148fb1d0 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -922,7 +922,7 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
                 return r;
 
         if (free_blocks <= pool->low_water_blocks && !pool->low_water_triggered) {
-                DMWARN("%s: reached low water mark, sending event.",
+                DMWARN("%s: reached low water mark for data device: sending event.",
                        dm_device_name(pool->pool_md));
                 spin_lock_irqsave(&pool->lock, flags);
                 pool->low_water_triggered = 1;
@@ -1909,6 +1909,20 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
         return r;
 }
 
+static sector_t get_metadata_dev_size(struct block_device *bdev)
+{
+        sector_t metadata_dev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
+        char buffer[BDEVNAME_SIZE];
+
+        if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING) {
+                DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
+                       bdevname(bdev, buffer), THIN_METADATA_MAX_SECTORS);
+                metadata_dev_size = THIN_METADATA_MAX_SECTORS_WARNING;
+        }
+
+        return metadata_dev_size;
+}
+
 /*
  * thin-pool <metadata dev> <data dev>
  *           <data block size (sectors)>
@@ -1931,8 +1945,6 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
         unsigned long block_size;
         dm_block_t low_water_blocks;
         struct dm_dev *metadata_dev;
-        sector_t metadata_dev_size;
-        char b[BDEVNAME_SIZE];
 
         /*
          * FIXME Remove validation from scope of lock.
@@ -1953,10 +1965,11 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
                 goto out_unlock;
         }
 
-        metadata_dev_size = i_size_read(metadata_dev->bdev->bd_inode) >> SECTOR_SHIFT;
-        if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING)
-                DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
-                       bdevname(metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
+        /*
+         * Run for the side-effect of possibly issuing a warning if the
+         * device is too big.
+         */
+        (void) get_metadata_dev_size(metadata_dev->bdev);
 
         r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &data_dev);
         if (r) {
@@ -2079,18 +2092,7 @@ static int pool_map(struct dm_target *ti, struct bio *bio)
         return r;
 }
 
-/*
- * Retrieves the number of blocks of the data device from
- * the superblock and compares it to the actual device size,
- * thus resizing the data device in case it has grown.
- *
- * This both copes with opening preallocated data devices in the ctr
- * being followed by a resume
- * -and-
- * calling the resume method individually after userspace has
- * grown the data device in reaction to a table event.
- */
-static int pool_preresume(struct dm_target *ti)
+static int maybe_resize_data_dev(struct dm_target *ti, bool *need_commit)
 {
         int r;
         struct pool_c *pt = ti->private;
@@ -2098,12 +2100,7 @@ static int pool_preresume(struct dm_target *ti)
         sector_t data_size = ti->len;
         dm_block_t sb_data_size;
 
-        /*
-         * Take control of the pool object.
-         */
-        r = bind_control_target(pool, ti);
-        if (r)
-                return r;
+        *need_commit = false;
 
         (void) sector_div(data_size, pool->sectors_per_block);
 
@@ -2114,7 +2111,7 @@ static int pool_preresume(struct dm_target *ti)
         }
 
         if (data_size < sb_data_size) {
-                DMERR("pool target too small, is %llu blocks (expected %llu)",
+                DMERR("pool target (%llu blocks) too small: expected %llu",
                       (unsigned long long)data_size, sb_data_size);
                 return -EINVAL;
 
@@ -2122,17 +2119,51 @@ static int pool_preresume(struct dm_target *ti)
                 r = dm_pool_resize_data_dev(pool->pmd, data_size);
                 if (r) {
                         DMERR("failed to resize data device");
-                        /* FIXME Stricter than necessary: Rollback transaction instead here */
                         set_pool_mode(pool, PM_READ_ONLY);
                         return r;
                 }
 
-                (void) commit_or_fallback(pool);
+                *need_commit = true;
         }
 
         return 0;
 }
 
+/*
+ * Retrieves the number of blocks of the data device from
+ * the superblock and compares it to the actual device size,
+ * thus resizing the data device in case it has grown.