dm thin metadata: speed up discard of partially mapped volumes

Use dm_btree_lookup_next() to more quickly discard partially mapped
volumes.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index c219a053c7f66d1ebae80a19b005af38914dbe8c..7547315ff18a3147386fd39243fd7edaee906e11 100644 (file)
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1395,6 +1395,19 @@ static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
        return td->snapshotted_time > time;
 }
 
+static void unpack_lookup_result(struct dm_thin_device *td, __le64 value,
+                                struct dm_thin_lookup_result *result)
+{
+       uint64_t block_time = 0;
+       dm_block_t exception_block;
+       uint32_t exception_time;
+
+       block_time = le64_to_cpu(value);
+       unpack_block_time(block_time, &exception_block, &exception_time);
+       result->block = exception_block;
+       result->shared = __snapshotted_since(td, exception_time);
+}
+
 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
                       int can_issue_io, struct dm_thin_lookup_result *result)
 {
@@ -1416,23 +1429,36 @@ int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
                info = &pmd->nb_info;
 
        r = dm_btree_lookup(info, pmd->root, keys, &value);
-       if (!r) {
-               uint64_t block_time = 0;
-               dm_block_t exception_block;
-               uint32_t exception_time;
-
-               block_time = le64_to_cpu(value);
-               unpack_block_time(block_time, &exception_block,
-                                 &exception_time);
-               result->block = exception_block;
-               result->shared = __snapshotted_since(td, exception_time);
+       if (!r)
+               unpack_lookup_result(td, value, result);
+
+       up_read(&pmd->root_lock);
+       return r;
+}
+
+static int dm_thin_find_next_mapped_block(struct dm_thin_device *td, dm_block_t block,
+                                         dm_block_t *vblock,
+                                         struct dm_thin_lookup_result *result)
+{
+       int r;
+       __le64 value;
+       struct dm_pool_metadata *pmd = td->pmd;
+       dm_block_t keys[2] = { td->id, block };
+
+       down_read(&pmd->root_lock);
+       if (pmd->fail_io) {
+               up_read(&pmd->root_lock);
+               return -EINVAL;
        }
 
+       r = dm_btree_lookup_next(&pmd->info, pmd->root, keys, vblock, &value);
+       if (!r)
+               unpack_lookup_result(td, value, result);
+
        up_read(&pmd->root_lock);
        return r;
 }
 
-/* FIXME: write a more efficient one in btree */
 int dm_thin_find_mapped_range(struct dm_thin_device *td,
                              dm_block_t begin, dm_block_t end,
                              dm_block_t *thin_begin, dm_block_t *thin_end,
@@ -1445,21 +1471,11 @@ int dm_thin_find_mapped_range(struct dm_thin_device *td,
        if (end < begin)
                return -ENODATA;
 
-       /*
-        * Find first mapped block.
-        */
-       while (begin < end) {
-               r = dm_thin_find_block(td, begin, true, &lookup);
-               if (r) {
-                       if (r != -ENODATA)
-                               return r;
-               } else
-                       break;
-
-               begin++;
-       }
+       r = dm_thin_find_next_mapped_block(td, begin, &begin, &lookup);
+       if (r)
+               return r;
 
-       if (begin == end)
+       if (begin >= end)
                return -ENODATA;
 
        *thin_begin = begin;