btrfs: move and export can_overcommit

This is the first piece of moving the space reservation code to
space-info.c
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

@@ -4147,11 +4147,6 @@ static void force_metadata_allocation(struct btrfs_fs_info *info)
 	rcu_read_unlock();
 }
 
-static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
-{
-	return (global->size << 1);
-}
-
 static int should_alloc_chunk(struct btrfs_fs_info *fs_info,
 			      struct btrfs_space_info *sinfo, int force)
 {
@@ -4376,69 +4371,6 @@ int btrfs_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags,
 	return ret;
 }
 
-static int can_overcommit(struct btrfs_fs_info *fs_info,
-			  struct btrfs_space_info *space_info, u64 bytes,
-			  enum btrfs_reserve_flush_enum flush,
-			  bool system_chunk)
-{
-	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
-	u64 profile;
-	u64 space_size;
-	u64 avail;
-	u64 used;
-	int factor;
-
-	/* Don't overcommit when in mixed mode. */
-	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
-		return 0;
-
-	if (system_chunk)
-		profile = btrfs_system_alloc_profile(fs_info);
-	else
-		profile = btrfs_metadata_alloc_profile(fs_info);
-
-	used = btrfs_space_info_used(space_info, false);
-
-	/*
-	 * We only want to allow over committing if we have lots of actual space
-	 * free, but if we don't have enough space to handle the global reserve
-	 * space then we could end up having a real enospc problem when trying
-	 * to allocate a chunk or some other such important allocation.
-	 */
-	spin_lock(&global_rsv->lock);
-	space_size = calc_global_rsv_need_space(global_rsv);
-	spin_unlock(&global_rsv->lock);
-	if (used + space_size >= space_info->total_bytes)
-		return 0;
-
-	used += space_info->bytes_may_use;
-
-	avail = atomic64_read(&fs_info->free_chunk_space);
-
-	/*
-	 * If we have dup, raid1 or raid10 then only half of the free
-	 * space is actually usable.  For raid56, the space info used
-	 * doesn't include the parity drive, so we don't have to
-	 * change the math
-	 */
-	factor = btrfs_bg_type_to_factor(profile);
-	avail = div_u64(avail, factor);
-
-	/*
-	 * If we aren't flushing all things, let us overcommit up to
-	 * 1/2th of the space. If we can flush, don't let us overcommit
-	 * too much, let it overcommit up to 1/8 of the space.
-	 */
-	if (flush == BTRFS_RESERVE_FLUSH_ALL)
-		avail >>= 3;
-	else
-		avail >>= 1;
-
-	if (used + bytes < space_info->total_bytes + avail)
-		return 1;
-	return 0;
-}
-
 static void btrfs_writeback_inodes_sb_nr(struct btrfs_fs_info *fs_info,
 					 unsigned long nr_pages, int nr_items)
 {
@@ -4766,14 +4698,14 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 		return to_reclaim;
 
 	to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
-	if (can_overcommit(fs_info, space_info, to_reclaim,
-			   BTRFS_RESERVE_FLUSH_ALL, system_chunk))
+	if (btrfs_can_overcommit(fs_info, space_info, to_reclaim,
+				 BTRFS_RESERVE_FLUSH_ALL, system_chunk))
 		return 0;
 
 	used = btrfs_space_info_used(space_info, true);
 
-	if (can_overcommit(fs_info, space_info, SZ_1M,
-			   BTRFS_RESERVE_FLUSH_ALL, system_chunk))
+	if (btrfs_can_overcommit(fs_info, space_info, SZ_1M,
+				 BTRFS_RESERVE_FLUSH_ALL, system_chunk))
 		expected = div_factor_fine(space_info->total_bytes, 95);
 	else
 		expected = div_factor_fine(space_info->total_bytes, 90);
@@ -5019,8 +4951,8 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
 		trace_btrfs_space_reservation(fs_info, "space_info",
 					      space_info->flags, orig_bytes, 1);
 		ret = 0;
-	} else if (can_overcommit(fs_info, space_info, orig_bytes, flush,
-				  system_chunk)) {
+	} else if (btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush,
+					system_chunk)) {
 		update_bytes_may_use(fs_info, space_info, orig_bytes);
 		trace_btrfs_space_reservation(fs_info, "space_info",
 					      space_info->flags, orig_bytes, 1);
@@ -5331,7 +5263,7 @@ void btrfs_space_info_add_old_bytes(struct btrfs_fs_info *fs_info,
 		 * adding the ticket space would be a double count.
 		 */
 		if (check_overcommit &&
-		    !can_overcommit(fs_info, space_info, 0, flush, false))
+		    !btrfs_can_overcommit(fs_info, space_info, 0, flush, false))
 			break;
 		if (num_bytes >= ticket->bytes) {
 			list_del_init(&ticket->list);

fs/btrfs/space-info.c

@@ -172,3 +172,71 @@ struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
 	rcu_read_unlock();
 	return NULL;
 }
+
+static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
+{
+	return (global->size << 1);
+}
+
+int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
+			 struct btrfs_space_info *space_info, u64 bytes,
+			 enum btrfs_reserve_flush_enum flush,
+			 bool system_chunk)
+{
+	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
+	u64 profile;
+	u64 space_size;
+	u64 avail;
+	u64 used;
+	int factor;
+
+	/* Don't overcommit when in mixed mode. */
+	if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
+		return 0;
+
+	if (system_chunk)
+		profile = btrfs_system_alloc_profile(fs_info);
+	else
+		profile = btrfs_metadata_alloc_profile(fs_info);
+
+	used = btrfs_space_info_used(space_info, false);
+
+	/*
+	 * We only want to allow over committing if we have lots of actual space
+	 * free, but if we don't have enough space to handle the global reserve
+	 * space then we could end up having a real enospc problem when trying
+	 * to allocate a chunk or some other such important allocation.
+	 */
+	spin_lock(&global_rsv->lock);
+	space_size = calc_global_rsv_need_space(global_rsv);
+	spin_unlock(&global_rsv->lock);
+	if (used + space_size >= space_info->total_bytes)
+		return 0;
+
+	used += space_info->bytes_may_use;
+
+	avail = atomic64_read(&fs_info->free_chunk_space);
+
+	/*
+	 * If we have dup, raid1 or raid10 then only half of the free
+	 * space is actually usable.  For raid56, the space info used
+	 * doesn't include the parity drive, so we don't have to
+	 * change the math
+	 */
+	factor = btrfs_bg_type_to_factor(profile);
+	avail = div_u64(avail, factor);
+
+	/*
+	 * If we aren't flushing all things, let us overcommit up to
+	 * 1/2th of the space. If we can flush, don't let us overcommit
+	 * too much, let it overcommit up to 1/8 of the space.
+	 */
+	if (flush == BTRFS_RESERVE_FLUSH_ALL)
+		avail >>= 3;
+	else
+		avail >>= 1;
+
+	if (used + bytes < space_info->total_bytes + avail)
+		return 1;
+	return 0;
+}

fs/btrfs/space-info.h

@@ -91,5 +91,9 @@ struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
 u64 btrfs_space_info_used(struct btrfs_space_info *s_info,
 			  bool may_use_included);
 void btrfs_clear_space_info_full(struct btrfs_fs_info *info);
+int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
+			 struct btrfs_space_info *space_info, u64 bytes,
+			 enum btrfs_reserve_flush_enum flush,
+			 bool system_chunk);
 
 #endif /* BTRFS_SPACE_INFO_H */