[PATCH 16/21] 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 |   45 +++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_dir2.h |    3 +++
 fs/xfs/xfs_inode.c       |   22 +---------------------
 3 files changed, 49 insertions(+), 21 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index 2a41aa2b3b30..3b727944f756 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -794,3 +794,48 @@ xfs_dir_create_new_child(
 	xfs_bumplink(tp, dp);
 	return 0;
 }
+
+/*
+ * 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);
+
+	xfs_bumplink(tp, ip);
+	return 0;
+}
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index de38d6335a72..14ade8f81bcc 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -253,5 +253,8 @@ bool xfs_dir2_namecheck(const void *name, size_t length);
 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 b3ff374025dd..80aa21149bd9 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -975,29 +975,9 @@ 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);
+	error = xfs_dir_link_existing_child(tp, resblks, tdp, target_name, sip);
 	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);
-
-	xfs_bumplink(tp, sip);
 
 	/*
 	 * If this is a synchronous mount, make sure that the