diff --git a/Lib/os.py b/Lib/os.py
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -110,6 +110,7 @@
 
 # Python uses fixed values for the SEEK_ constants; they are mapped
 # to native constants if necessary in posixmodule.c
+# Other possible SEEK values are directly imported from posixmodule.c
 SEEK_SET = 0
 SEEK_CUR = 1
 SEEK_END = 2
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -135,6 +135,8 @@
 Extensions
 ----------
 
+- Issue #10142: Support for SEEK_HOLE/SEEK_DATA (for instance, under ZFS).
+
 - Issue #10143: Update "os.pathconf" values.
 
 - Issue #6518: Support context manager protcol for ossaudiodev types.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -8151,6 +8151,14 @@
     if (ins(d, "O_EXLOCK", (long)O_EXLOCK)) return -1;
 #endif
 
+/* Solaris */
+#ifdef SEEK_HOLE /* ZFS */
+    if (ins(d, "SEEK_HOLE", (long)SEEK_HOLE)) return -1;
+#endif
+#ifdef SEEK_DATA /* ZFS */
+    if (ins(d, "SEEK_DATA", (long)SEEK_DATA)) return -1;
+#endif
+
 /* MS Windows */
 #ifdef O_NOINHERIT
     /* Don't inherit in child processes. */