btrfs: use the same helper for data and metadata reservations

Now that data reservations follow the same pattern as metadata
reservations we can simply rename __reserve_metadata_bytes to
__reserve_bytes and use that helper for data reservations.

Things to keep in mind, btrfs_can_overcommit() returns 0 for data,
because we can never overcommit.  We also will never pass in FLUSH_ALL
for data, so we'll simply be added to the priority list and go straight
into handle_reserve_ticket.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/space-info.c

@@ -1249,10 +1249,9 @@ static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
  * regain reservations will be made and this will fail if there is not enough
  * space already.
  */
-static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
-				    struct btrfs_space_info *space_info,
-				    u64 orig_bytes,
-				    enum btrfs_reserve_flush_enum flush)
+static int __reserve_bytes(struct btrfs_fs_info *fs_info,
+			   struct btrfs_space_info *space_info, u64 orig_bytes,
+			   enum btrfs_reserve_flush_enum flush)
 {
 	struct reserve_ticket ticket;
 	u64 used;
@@ -1364,8 +1363,7 @@ int btrfs_reserve_metadata_bytes(struct btrfs_root *root,
 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
 	int ret;
 
-	ret = __reserve_metadata_bytes(fs_info, block_rsv->space_info,
-				       orig_bytes, flush);
+	ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush);
 	if (ret == -ENOSPC &&
 	    unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
 		if (block_rsv != global_rsv &&
@@ -1397,36 +1395,18 @@ int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
 			     enum btrfs_reserve_flush_enum flush)
 {
 	struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
-	u64 used;
-	int ret = -ENOSPC;
-	bool pending_tickets;
+	int ret;
 
+	ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
+	       flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE);
 	ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
 
-	spin_lock(&data_sinfo->lock);
-	used = btrfs_space_info_used(data_sinfo, true);
-	pending_tickets = !list_empty(&data_sinfo->tickets) ||
-			  !list_empty(&data_sinfo->priority_tickets);
-
-	if (pending_tickets || used + bytes > data_sinfo->total_bytes) {
-		struct reserve_ticket ticket;
-
-		init_waitqueue_head(&ticket.wait);
-		ticket.bytes = bytes;
-		ticket.error = 0;
-		list_add_tail(&ticket.list, &data_sinfo->priority_tickets);
-		data_sinfo->reclaim_size += bytes;
-		spin_unlock(&data_sinfo->lock);
-
-		ret = handle_reserve_ticket(fs_info, data_sinfo, &ticket, flush);
-	} else {
-		btrfs_space_info_update_bytes_may_use(fs_info, data_sinfo, bytes);
-		ret = 0;
-		spin_unlock(&data_sinfo->lock);
-	}
-	if (ret)
-		trace_btrfs_space_reservation(fs_info,
-					      "space_info:enospc",
+	ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
+	if (ret == -ENOSPC) {
+		trace_btrfs_space_reservation(fs_info, "space_info:enospc",
 					      data_sinfo->flags, bytes, 1);
+		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
+			btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);
+	}
 	return ret;
 }