[PATCH 21/22] xfs: split xfs_initialize_perag

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Christoph Hellwig <hch@xxxxxx>

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

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_ag.c |  119 +++++++++++++++++++++++++++---------------------
 1 file changed, 67 insertions(+), 52 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 6d8a1e42615dec..3e232b3d4c4262 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -293,6 +293,67 @@ xfs_update_last_ag_size(
 	return 0;
 }
 
+static int
+xfs_perag_alloc(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		index,
+	xfs_agnumber_t		agcount,
+	xfs_rfsblock_t		dblocks)
+{
+	struct xfs_perag	*pag;
+	int			error;
+
+	pag = kzalloc(sizeof(*pag), GFP_KERNEL);
+	if (!pag)
+		return -ENOMEM;
+
+	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);
+#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, agcount, dblocks);
+	pag->min_block = XFS_AGFL_BLOCK(mp);
+	__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
+			&pag->agino_max);
+
+	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,
@@ -301,68 +362,22 @@ xfs_initialize_perag(
 	xfs_rfsblock_t		dblocks,
 	xfs_agnumber_t		*maxagi)
 {
-	struct xfs_perag	*pag;
 	xfs_agnumber_t		index;
 	int			error;
 
+	if (orig_agcount >= new_agcount)
+		return 0;
+
 	for (index = orig_agcount; index < new_agcount; index++) {
-		pag = kzalloc(sizeof(*pag), GFP_KERNEL);
-		if (!pag) {
-			error = -ENOMEM;
+		error = xfs_perag_alloc(mp, index, new_agcount, dblocks);
+		if (error)
 			goto out_unwind_new_pags;
-		}
-		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);
-#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);
 	}
 
-	index = xfs_set_inode_alloc(mp, new_agcount);
-
-	if (maxagi)
-		*maxagi = index;
-
+	*maxagi = xfs_set_inode_alloc(mp, new_agcount);
 	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);
 out_unwind_new_pags:
 	xfs_free_perag_range(mp, orig_agcount, index);
 	return error;