xfs: clean up xfs_mount allocation and dynamic initializers

Most of the generic data structures embedded in xfs_mount are
dynamically initialized immediately after mp is allocated. A few
fields are left out and initialized during the xfs_mountfs()
sequence, after mp has been attached to the superblock.

To clean this up and help prevent premature access of associated
fields, refactor xfs_mount allocation and all dependent init calls
into a new helper. This self-documents that all low level data
structures (i.e., locks, trees, etc.) should be initialized before
xfs_mount is attached to the superblock.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 29 insertions, 10 deletions

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 951271f57d00..612c1d5348b3 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1579,29 +1579,48 @@ xfs_destroy_percpu_counters(
 	percpu_counter_destroy(&mp->m_fdblocks);
 }
 
-STATIC int
-xfs_fs_fill_super(
-	struct super_block	*sb,
-	void			*data,
-	int			silent)
+static struct xfs_mount *
+xfs_mount_alloc(
+	struct super_block	*sb)
 {
-	struct inode		*root;
-	struct xfs_mount	*mp = NULL;
-	int			flags = 0, error = -ENOMEM;
+	struct xfs_mount	*mp;
 
 	mp = kzalloc(sizeof(struct xfs_mount), GFP_KERNEL);
 	if (!mp)
-		goto out;
+		return NULL;
 
+	mp->m_super = sb;
 	spin_lock_init(&mp->m_sb_lock);
+	spin_lock_init(&mp->m_agirotor_lock);
+	INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
+	spin_lock_init(&mp->m_perag_lock);
 	mutex_init(&mp->m_growlock);
 	atomic_set(&mp->m_active_trans, 0);
 	INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker);
 	INIT_DELAYED_WORK(&mp->m_eofblocks_work, xfs_eofblocks_worker);
 	INIT_DELAYED_WORK(&mp->m_cowblocks_work, xfs_cowblocks_worker);
 	mp->m_kobj.kobject.kset = xfs_kset;
+	return mp;
+}
 
-	mp->m_super = sb;
+
+STATIC int
+xfs_fs_fill_super(
+	struct super_block	*sb,
+	void			*data,
+	int			silent)
+{
+	struct inode		*root;
+	struct xfs_mount	*mp = NULL;
+	int			flags = 0, error = -ENOMEM;
+
+	/*
+	 * allocate mp and do all low-level struct initializations before we
+	 * attach it to the super
+	 */
+	mp = xfs_mount_alloc(sb);
+	if (!mp)
+		goto out;
 	sb->s_fs_info = mp;
 
 	error = xfs_parseargs(mp, (char *)data);