xfs: split xfs_initialize_perag

Factor out a xfs_perag_alloc helper that allocates a single perag
structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Author: Christoph Hellwig

fs/xfs/libxfs/xfs_ag.c

@@ -272,6 +272,10 @@ xfs_agino_range(
 	return __xfs_agino_range(mp, xfs_ag_block_count(mp, agno), first, last);
 }
 
+/*
+ * Update the perag of the previous tail AG if it has been changed during
+ * recovery (i.e. recovery of a growfs).
+ */
 int
 xfs_update_last_ag_size(
 	struct xfs_mount	*mp,
@@ -289,78 +293,93 @@ xfs_update_last_ag_size(
 	return 0;
 }
 
-int
-xfs_initialize_perag(
+static int
+xfs_perag_alloc(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		old_agcount,
-	xfs_agnumber_t		new_agcount,
-	xfs_rfsblock_t		dblocks,
-	xfs_agnumber_t		*maxagi)
+	xfs_agnumber_t		index,
+	xfs_agnumber_t		agcount,
+	xfs_rfsblock_t		dblocks)
 {
 	struct xfs_perag	*pag;
-	xfs_agnumber_t		index;
 	int			error;
 
-	for (index = old_agcount; index < new_agcount; index++) {
-		pag = kzalloc(sizeof(*pag), GFP_KERNEL);
-		if (!pag) {
-			error = -ENOMEM;
-			goto out_unwind_new_pags;
-		}
-		pag->pag_agno = index;
-		pag->pag_mount = mp;
+	pag = kzalloc(sizeof(*pag), GFP_KERNEL);
+	if (!pag)
+		return -ENOMEM;
 
-		error = xa_insert(&mp->m_perags, index, pag, GFP_KERNEL);
-		if (error) {
-			WARN_ON_ONCE(error == -EBUSY);
-			goto out_free_pag;
-		}
+	pag->pag_agno = index;
+	pag->pag_mount = mp;
+
+	error = xa_insert(&mp->m_perags, index, pag, GFP_KERNEL);
+	if (error) {
+		WARN_ON_ONCE(error == -EBUSY);
+		goto out_free_pag;
+	}
 
 #ifdef __KERNEL__
-		/* Place kernel structure only init below this point. */
-		spin_lock_init(&pag->pag_ici_lock);
-		spin_lock_init(&pag->pagb_lock);
-		spin_lock_init(&pag->pag_state_lock);
-		INIT_DELAYED_WORK(&pag->pag_blockgc_work, xfs_blockgc_worker);
-		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
-		xfs_defer_drain_init(&pag->pag_intents_drain);
-		init_waitqueue_head(&pag->pagb_wait);
-		pag->pagb_tree = RB_ROOT;
-		xfs_hooks_init(&pag->pag_rmap_update_hooks);
+	/* Place kernel structure only init below this point. */
+	spin_lock_init(&pag->pag_ici_lock);
+	spin_lock_init(&pag->pagb_lock);
+	spin_lock_init(&pag->pag_state_lock);
+	INIT_DELAYED_WORK(&pag->pag_blockgc_work, xfs_blockgc_worker);
+	INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
+	xfs_defer_drain_init(&pag->pag_intents_drain);
+	init_waitqueue_head(&pag->pagb_wait);
+	pag->pagb_tree = RB_ROOT;
+	xfs_hooks_init(&pag->pag_rmap_update_hooks);
 #endif /* __KERNEL__ */
 
-		error = xfs_buf_cache_init(&pag->pag_bcache);
-		if (error)
-			goto out_remove_pag;
-
-		/* Active ref owned by mount indicates AG is online. */
-		atomic_set(&pag->pag_active_ref, 1);
-
-		/*
-		 * Pre-calculated geometry
-		 */
-		pag->block_count = __xfs_ag_block_count(mp, index, new_agcount,
-				dblocks);
-		pag->min_block = XFS_AGFL_BLOCK(mp);
-		__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
-				&pag->agino_max);
-	}
+	error = xfs_buf_cache_init(&pag->pag_bcache);
+	if (error)
+		goto out_remove_pag;
 
-	index = xfs_set_inode_alloc(mp, new_agcount);
+	/* Active ref owned by mount indicates AG is online. */
+	atomic_set(&pag->pag_active_ref, 1);
 
-	if (maxagi)
-		*maxagi = index;
+	/*
+	 * Pre-calculated geometry
+	 */
+	pag->block_count = __xfs_ag_block_count(mp, index, agcount, dblocks);
+	pag->min_block = XFS_AGFL_BLOCK(mp);
+	__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
+			&pag->agino_max);
 
-	mp->m_ag_prealloc_blocks = xfs_prealloc_blocks(mp);
 	return 0;
 
 out_remove_pag:
 	xfs_defer_drain_free(&pag->pag_intents_drain);
 	pag = xa_erase(&mp->m_perags, index);
 out_free_pag:
 	kfree(pag);
+	return error;
+}
+
+int
+xfs_initialize_perag(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		orig_agcount,
+	xfs_agnumber_t		new_agcount,
+	xfs_rfsblock_t		dblocks,
+	xfs_agnumber_t		*maxagi)
+{
+	xfs_agnumber_t		index;
+	int			error;
+
+	if (orig_agcount >= new_agcount)
+		return 0;
+
+	for (index = orig_agcount; index < new_agcount; index++) {
+		error = xfs_perag_alloc(mp, index, new_agcount, dblocks);
+		if (error)
+			goto out_unwind_new_pags;
+	}
+
+	*maxagi = xfs_set_inode_alloc(mp, new_agcount);
+	mp->m_ag_prealloc_blocks = xfs_prealloc_blocks(mp);
+	return 0;
+
 out_unwind_new_pags:
-	xfs_free_perag_range(mp, old_agcount, index);
+	xfs_free_perag_range(mp, orig_agcount, index);
 	return error;
 }
 

fs/xfs/libxfs/xfs_ag.h

@@ -142,8 +142,8 @@ __XFS_AG_OPSTATE(prefers_metadata, PREFERS_METADATA)
 __XFS_AG_OPSTATE(allows_inodes, ALLOWS_INODES)
 __XFS_AG_OPSTATE(agfl_needs_reset, AGFL_NEEDS_RESET)
 
-int xfs_initialize_perag(struct xfs_mount *mp, xfs_agnumber_t old_agcount,
-		xfs_agnumber_t agcount, xfs_rfsblock_t dcount,
+int xfs_initialize_perag(struct xfs_mount *mp, xfs_agnumber_t orig_agcount,
+		xfs_agnumber_t new_agcount, xfs_rfsblock_t dcount,
 		xfs_agnumber_t *maxagi);
 void xfs_free_perag_range(struct xfs_mount *mp, xfs_agnumber_t first_agno,
 		xfs_agnumber_t end_agno);

fs/xfs/xfs_buf_item_recover.c

@@ -724,9 +724,8 @@ xlog_recover_do_primary_sb_buffer(
 	}
 
 	/*
-	 * Growfs can also grow the last existing AG.  In this case we also need
-	 * to update the length in the in-core perag structure and values
-	 * depending on it.
+	 * If the last AG was grown or shrunk, we also need to update the
+	 * length in the in-core perag structure and values depending on it.
 	 */
 	error = xfs_update_last_ag_size(mp, orig_agcount);
 	if (error)