[PATCH 16/22] xfs: create libxfs helper to link an existing inode into a directory

["Darrick J. Wong" <darrick.wong@xxxxxxxxxx>]

From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>

Create a new libxfs function to link an existing inode into a directory.
The upcoming metadata directory feature will need this to create a
metadata directory tree.

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_dir2.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_dir2.h |    3 +++
 fs/xfs/xfs_inode.c       |   24 +-----------------------
 3 files changed, 48 insertions(+), 23 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index aaac55668e9d..4cd2afa234ca 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -748,3 +748,47 @@ xfs_dir_create_new_child(
 
 	return xfs_bumplink(tp, dp);
 }
+
+/*
+ * Given a directory @dp, an existing non-directory inode @ip, and a @name,
+ * link @ip into @dp under the given @name.  Both inodes must have the ILOCK
+ * held.
+ */
+int
+xfs_dir_link_existing_child(
+	struct xfs_trans		*tp,
+	uint				resblks,
+	struct xfs_inode		*dp,
+	struct xfs_name			*name,
+	struct xfs_inode		*ip)
+{
+	int				error;
+
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	ASSERT(xfs_isilocked(dp, XFS_ILOCK_EXCL));
+	ASSERT(!S_ISDIR(VFS_I(ip)->i_mode));
+
+	if (!resblks) {
+		error = xfs_dir_canenter(tp, dp, name);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * Handle initial link state of O_TMPFILE inode
+	 */
+	if (VFS_I(ip)->i_nlink == 0) {
+		error = xfs_iunlink_remove(tp, ip);
+		if (error)
+			return error;
+	}
+
+	error = xfs_dir_createname(tp, dp, name, ip->i_ino, resblks);
+	if (error)
+		return error;
+
+	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
+
+	return xfs_bumplink(tp, ip);
+}
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index 5219ca503012..7e713fcb4c40 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -330,5 +330,8 @@ void *xfs_dir3_data_endp(struct xfs_da_geometry *geo,
 int xfs_dir_create_new_child(struct xfs_trans *tp, uint resblks,
 		struct xfs_inode *dp, struct xfs_name *name,
 		struct xfs_inode *ip);
+int xfs_dir_link_existing_child(struct xfs_trans *tp, uint resblks,
+		struct xfs_inode *dp, struct xfs_name *name,
+		struct xfs_inode *ip);
 
 #endif	/* __XFS_DIR2_H__ */
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 1469f905be36..189f11bba539 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -974,29 +974,7 @@ xfs_link(
 		goto error_return;
 	}
 
-	if (!resblks) {
-		error = xfs_dir_canenter(tp, tdp, target_name);
-		if (error)
-			goto error_return;
-	}
-
-	/*
-	 * Handle initial link state of O_TMPFILE inode
-	 */
-	if (VFS_I(sip)->i_nlink == 0) {
-		error = xfs_iunlink_remove(tp, sip);
-		if (error)
-			goto error_return;
-	}
-
-	error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
-				   resblks);
-	if (error)
-		goto error_return;
-	xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
-	xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);
-
-	error = xfs_bumplink(tp, sip);
+	error = xfs_dir_link_existing_child(tp, resblks, tdp, target_name, sip);
 	if (error)
 		goto error_return;