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>

1 files changed, 41 insertions, 25 deletions

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index c219a053c7f6..7547315ff18a 100644
--- 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;