xfs: create libxfs helper to link an existing inode into a directory

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 <djwong@kernel.org>

2 files changed, 54 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index 766347beeafc..68ebc8110f4e 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -21,6 +21,7 @@
 #include "xfs_health.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_trans_space.h"
+#include "xfs_ag.h"
 
 struct xfs_name xfs_name_dotdot = { (unsigned char *)"..", 2, XFS_DIR3_FT_DIR };
 
@@ -792,3 +793,53 @@ 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)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	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) {
+		struct xfs_perag	*pag;
+
+		pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
+		error = xfs_iunlink_remove(tp, pag, ip);
+		xfs_perag_put(pag);
+		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 a4ac61b00db3..5150a54d332a 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -251,5 +251,8 @@ 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__ */