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>
Reviewed-by: Christoph Hellwig <hch@lst.de>

2 files changed, 71 insertions, 4 deletions

diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index bbed03441f5c..5a75f60e8518 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -22,6 +22,7 @@
 #include "xfs_bmap_btree.h"
 #include "xfs_trans_space.h"
 #include "xfs_parent.h"
+#include "xfs_ag.h"
 
 const struct xfs_name xfs_name_dotdot = {
 	.name	= (const unsigned char *)"..",
@@ -587,9 +588,9 @@ xfs_dir_replace(
  */
 int
 xfs_dir_canenter(
-	xfs_trans_t	*tp,
-	xfs_inode_t	*dp,
-	struct xfs_name	*name)		/* name of entry to add */
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	const struct xfs_name	*name)		/* name of entry to add */
 {
 	return xfs_dir_createname(tp, dp, name, 0, 0);
 }
@@ -809,3 +810,67 @@ xfs_dir_create_child(
 
 	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_add_child(
+	struct xfs_trans	*tp,
+	unsigned int		resblks,
+	struct xfs_dir_update	*du)
+{
+	struct xfs_inode	*dp = du->dp;
+	const struct xfs_name	*name = du->name;
+	struct xfs_inode	*ip = du->ip;
+	struct xfs_mount	*mp = tp->t_mountp;
+	int			error;
+
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
+	xfs_assert_ilocked(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);
+
+	/*
+	 * If we have parent pointers, we now need to add the parent record to
+	 * the attribute fork of the inode. If this is the initial parent
+	 * attribute, we need to create it correctly, otherwise we can just add
+	 * the parent to the inode.
+	 */
+	if (du->ppargs) {
+		error = xfs_parent_addname(tp, du->ppargs, dp, name, ip);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index a1ba6fd0a725..4f9711509571 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -74,7 +74,7 @@ extern int xfs_dir_replace(struct xfs_trans *tp, struct xfs_inode *dp,
 				const struct xfs_name *name, xfs_ino_t inum,
 				xfs_extlen_t tot);
 extern int xfs_dir_canenter(struct xfs_trans *tp, struct xfs_inode *dp,
-				struct xfs_name *name);
+				const struct xfs_name *name);
 
 int xfs_dir_lookup_args(struct xfs_da_args *args);
 int xfs_dir_createname_args(struct xfs_da_args *args);
@@ -320,5 +320,7 @@ struct xfs_dir_update {
 
 int xfs_dir_create_child(struct xfs_trans *tp, unsigned int resblks,
 		struct xfs_dir_update *du);
+int xfs_dir_add_child(struct xfs_trans *tp, unsigned int resblks,
+		struct xfs_dir_update *du);
 
 #endif	/* __XFS_DIR2_H__ */