Add fix-stack-noinline topic branch

Certain function must never be automatically inlined by gcc because
they are stack heavy or called recursively.  This patch flags all
such functions I have found as 'noinline' to prevent gcc from making
the optimization.

.topdeps

@@ -0,0 +1 @@
+master

.topmsg

@@ -0,0 +1,9 @@
+From: Brian Behlendorf <behlendorf1@llnl.gov>
+Subject: [PATCH] fix stack noinline
+
+Certain function must never be automatically inlined by gcc because
+they are stack heavy or called recursively.  This patch flags all
+such functions I've found as 'noinline' to prevent gcc from making
+the optimization.
+
+Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

lib/libzpool/include/sys/zfs_context.h

@@ -77,6 +77,12 @@ extern "C" {
 #include <sys/sysevent/dev.h>
 #include <sys/sunddi.h>
 
+/*
+ * Stack
+ */
+
+#define  noinline	__attribute__((noinline))
+
 /*
  * Debugging
  */

module/zfs/dbuf.c

@@ -2085,7 +2085,11 @@ dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
 	}
 }
 
-static void
+/* dbuf_sync_indirect() is called recursively from dbuf_sync_list() so it
+ * is critical the we not allow the compiler to inline this function in to
+ * dbuf_sync_list() thereby drastically bloating the stack usage.
+ */
+noinline static void
 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
 {
 	dmu_buf_impl_t *db = dr->dr_dbuf;
@@ -2125,7 +2129,11 @@ dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
 	zio_nowait(zio);
 }
 
-static void
+/* dbuf_sync_leaf() is called recursively from dbuf_sync_list() so it is
+ * critical the we not allow the compiler to inline this function in to
+ * dbuf_sync_list() thereby drastically bloating the stack usage.
+ */
+noinline static void
 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
 {
 	arc_buf_t **datap = &dr->dt.dl.dr_data;

module/zfs/dmu_send.c

@@ -921,7 +921,7 @@ restore_read(struct restorearg *ra, int len)
 	return (rv);
 }
 
-static void
+noinline static void
 backup_byteswap(dmu_replay_record_t *drr)
 {
 #define	DO64(X) (drr->drr_u.X = BSWAP_64(drr->drr_u.X))
@@ -1001,7 +1001,7 @@ backup_byteswap(dmu_replay_record_t *drr)
 #undef DO32
 }
 
-static int
+noinline static int
 restore_object(struct restorearg *ra, objset_t *os, struct drr_object *drro)
 {
 	int err;
@@ -1085,7 +1085,7 @@ restore_object(struct restorearg *ra, objset_t *os, struct drr_object *drro)
 }
 
 /* ARGSUSED */
-static int
+noinline static int
 restore_freeobjects(struct restorearg *ra, objset_t *os,
     struct drr_freeobjects *drrfo)
 {
@@ -1109,7 +1109,7 @@ restore_freeobjects(struct restorearg *ra, objset_t *os,
 	return (0);
 }
 
-static int
+noinline static int
 restore_write(struct restorearg *ra, objset_t *os,
     struct drr_write *drrw)
 {
@@ -1254,7 +1254,7 @@ restore_spill(struct restorearg *ra, objset_t *os, struct drr_spill *drrs)
 }
 
 /* ARGSUSED */
-static int
+noinline static int
 restore_free(struct restorearg *ra, objset_t *os,
     struct drr_free *drrf)
 {