btrfs: factor out btrfs_return_free_space()

Factor out a part of unpin_extent_range() that returns space back to the
space info, prioritizing global block reserve.  Also, move the "len"
variable into the loop to clarify we don't need to carry it beyond an
iteration.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

3 files changed, 34 insertions, 21 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 2ce9e69ee8f8..64a199d93d64 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2700,15 +2700,15 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
 {
 	struct btrfs_block_group *cache = NULL;
 	struct btrfs_space_info *space_info;
-	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
 	struct btrfs_free_cluster *cluster = NULL;
-	u64 len;
 	u64 total_unpinned = 0;
 	u64 empty_cluster = 0;
 	bool readonly;
 	int ret = 0;
 
 	while (start <= end) {
+		u64 len;
+
 		readonly = false;
 		if (!cache ||
 		    start >= cache->start + cache->length) {
@@ -2766,25 +2766,8 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
 			readonly = true;
 		}
 		spin_unlock(&cache->lock);
-		if (!readonly && return_free_space &&
-		    global_rsv->space_info == space_info) {
-			spin_lock(&global_rsv->lock);
-			if (!global_rsv->full) {
-				u64 to_add = min(len, global_rsv->size -
-						      global_rsv->reserved);
-
-				global_rsv->reserved += to_add;
-				btrfs_space_info_update_bytes_may_use(fs_info,
-						space_info, to_add);
-				if (global_rsv->reserved >= global_rsv->size)
-					global_rsv->full = 1;
-				len -= to_add;
-			}
-			spin_unlock(&global_rsv->lock);
-		}
-		/* Add to any tickets we may have */
-		if (!readonly && return_free_space && len)
-			btrfs_try_granting_tickets(fs_info, space_info);
+		if (!readonly && return_free_space)
+			btrfs_return_free_space(space_info, len);
 		spin_unlock(&space_info->lock);
 	}
 
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 255e85f78313..8b6340c59bf2 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -2082,3 +2082,32 @@ void btrfs_reclaim_sweep(const struct btrfs_fs_info *fs_info)
 			do_reclaim_sweep(space_info, raid);
 	}
 }
+
+void btrfs_return_free_space(struct btrfs_space_info *space_info, u64 len)
+{
+	struct btrfs_fs_info *fs_info = space_info->fs_info;
+	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
+
+	lockdep_assert_held(&space_info->lock);
+
+	/* Prioritize the global reservation to receive the freed space. */
+	if (global_rsv->space_info != space_info)
+		goto grant;
+
+	spin_lock(&global_rsv->lock);
+	if (!global_rsv->full) {
+		u64 to_add = min(len, global_rsv->size - global_rsv->reserved);
+
+		global_rsv->reserved += to_add;
+		btrfs_space_info_update_bytes_may_use(fs_info, space_info, to_add);
+		if (global_rsv->reserved >= global_rsv->size)
+			global_rsv->full = 1;
+		len -= to_add;
+	}
+	spin_unlock(&global_rsv->lock);
+
+grant:
+	/* Add to any tickets we may have. */
+	if (len)
+		btrfs_try_granting_tickets(fs_info, space_info);
+}
diff --git a/fs/btrfs/space-info.h b/fs/btrfs/space-info.h
index efbecc0c5258..4c9e8aabee51 100644
--- a/fs/btrfs/space-info.h
+++ b/fs/btrfs/space-info.h
@@ -295,5 +295,6 @@ void btrfs_set_periodic_reclaim_ready(struct btrfs_space_info *space_info, bool
 bool btrfs_should_periodic_reclaim(struct btrfs_space_info *space_info);
 int btrfs_calc_reclaim_threshold(const struct btrfs_space_info *space_info);
 void btrfs_reclaim_sweep(const struct btrfs_fs_info *fs_info);
+void btrfs_return_free_space(struct btrfs_space_info *space_info, u64 len);
 
 #endif /* BTRFS_SPACE_INFO_H */