2 files changed, 52 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 5fbe24c31679..222e103356c6 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -2003,3 +2003,49 @@ xfs_ifork_init_cow(
 	ip->i_cformat = XFS_DINODE_FMT_EXTENTS;
 	ip->i_cnextents = 0;
 }
+
+/*
+ * Lookup the extent covering bno.
+ *
+ * If there is an extent covering bno return the extent index, and store the
+ * expanded extent structure in *gotp, and the extent index in *idx.
+ * If there is no extent covering bno, but there is an extent after it (e.g.
+ * it lies in a hole) return that extent in *gotp and its index in *idx
+ * instead.
+ * If bno is beyond the last extent return false, and return the index after
+ * the last valid index in *idxp.
+ */
+bool
+xfs_iext_lookup_extent(
+	struct xfs_inode	*ip,
+	struct xfs_ifork	*ifp,
+	xfs_fileoff_t		bno,
+	xfs_extnum_t		*idxp,
+	struct xfs_bmbt_irec	*gotp)
+{
+	struct xfs_bmbt_rec_host *ep;
+
+	XFS_STATS_INC(ip->i_mount, xs_look_exlist);
+
+	ep = xfs_iext_bno_to_ext(ifp, bno, idxp);
+	if (!ep)
+		return false;
+	xfs_bmbt_get_all(ep, gotp);
+	return true;
+}
+
+/*
+ * Return true if there is an extent at index idx, and return the expanded
+ * extent structure at idx in that case.  Else return false.
+ */
+bool
+xfs_iext_get_extent(
+	struct xfs_ifork	*ifp,
+	xfs_extnum_t		idx,
+	struct xfs_bmbt_irec	*gotp)
+{
+	if (idx < 0 || idx >= xfs_iext_count(ifp))
+		return false;
+	xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), gotp);
+	return true;
+}
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 8bf112e29aa1..7fb8365326d1 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -182,6 +182,12 @@ void		xfs_iext_irec_compact_pages(struct xfs_ifork *);
 void		xfs_iext_irec_compact_full(struct xfs_ifork *);
 void		xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
 
+bool		xfs_iext_lookup_extent(struct xfs_inode *ip,
+			struct xfs_ifork *ifp, xfs_fileoff_t bno,
+			xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
+bool		xfs_iext_get_extent(struct xfs_ifork *ifp, xfs_extnum_t idx,
+			struct xfs_bmbt_irec *gotp);
+
 extern struct kmem_zone	*xfs_ifork_zone;
 
 extern void xfs_ifork_init_cow(struct xfs_inode *ip);