1 files changed, 112 insertions, 33 deletions

diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index 373cab0f7807..fbe93804d24a 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -821,6 +821,77 @@ out_error:
 	return error;
 }
 
+#ifdef CONFIG_XFS_LIVE_HOOKS
+/*
+ * Use a static key here to reduce the overhead of rmapbt live updates.  If
+ * the compiler supports jump labels, the static branch will be replaced by a
+ * nop sled when there are no hook users.  Online fsck is currently the only
+ * caller, so this is a reasonable tradeoff.
+ *
+ * Note: Patching the kernel code requires taking the cpu hotplug lock.  Other
+ * parts of the kernel allocate memory with that lock held, which means that
+ * XFS callers cannot hold any locks that might be used by memory reclaim or
+ * writeback when calling the static_branch_{inc,dec} functions.
+ */
+DEFINE_STATIC_XFS_HOOK_SWITCH(xfs_rmap_hooks_switch);
+
+void
+xfs_rmap_hook_disable(void)
+{
+	xfs_hooks_switch_off(&xfs_rmap_hooks_switch);
+}
+
+void
+xfs_rmap_hook_enable(void)
+{
+	xfs_hooks_switch_on(&xfs_rmap_hooks_switch);
+}
+
+/* Call downstream hooks for a reverse mapping update. */
+static inline void
+xfs_rmap_update_hook(
+	struct xfs_trans		*tp,
+	struct xfs_perag		*pag,
+	enum xfs_rmap_intent_type	op,
+	xfs_agblock_t			startblock,
+	xfs_extlen_t			blockcount,
+	bool				unwritten,
+	const struct xfs_owner_info	*oinfo)
+{
+	if (xfs_hooks_switched_on(&xfs_rmap_hooks_switch)) {
+		struct xfs_rmap_update_params	p = {
+			.startblock	= startblock,
+			.blockcount	= blockcount,
+			.unwritten	= unwritten,
+			.oinfo		= *oinfo, /* struct copy */
+		};
+
+		if (pag)
+			xfs_hooks_call(&pag->pag_rmap_update_hooks, op, &p);
+	}
+}
+
+/* Call the specified function during a reverse mapping update. */
+int
+xfs_rmap_hook_add(
+	struct xfs_perag	*pag,
+	struct xfs_rmap_hook	*hook)
+{
+	return xfs_hooks_add(&pag->pag_rmap_update_hooks, &hook->update_hook);
+}
+
+/* Stop calling the specified function during a reverse mapping update. */
+void
+xfs_rmap_hook_del(
+	struct xfs_perag	*pag,
+	struct xfs_rmap_hook	*hook)
+{
+	xfs_hooks_del(&pag->pag_rmap_update_hooks, &hook->update_hook);
+}
+#else
+# define xfs_rmap_update_hook(t, p, o, s, b, u, oi)	do { } while(0)
+#endif /* CONFIG_XFS_LIVE_HOOKS */
+
 /*
  * Remove a reference to an extent in the rmap btree.
  */
@@ -841,7 +912,7 @@ xfs_rmap_free(
 		return 0;
 
 	cur = xfs_rmapbt_init_cursor(mp, tp, agbp, pag);
-
+	xfs_rmap_update_hook(tp, pag, XFS_RMAP_UNMAP, bno, len, false, oinfo);
 	error = xfs_rmap_unmap(cur, bno, len, false, oinfo);
 
 	xfs_btree_del_cursor(cur, error);
@@ -1093,6 +1164,7 @@ xfs_rmap_alloc(
 		return 0;
 
 	cur = xfs_rmapbt_init_cursor(mp, tp, agbp, pag);
+	xfs_rmap_update_hook(tp, pag, XFS_RMAP_MAP, bno, len, false, oinfo);
 	error = xfs_rmap_map(cur, bno, len, false, oinfo);
 
 	xfs_btree_del_cursor(cur, error);
@@ -2512,6 +2584,38 @@ xfs_rmap_finish_one_cleanup(
 		xfs_trans_brelse(tp, agbp);
 }
 
+/* Commit an rmap operation into the ondisk tree. */
+int
+__xfs_rmap_finish_intent(
+	struct xfs_btree_cur		*rcur,
+	enum xfs_rmap_intent_type	op,
+	xfs_agblock_t			bno,
+	xfs_extlen_t			len,
+	const struct xfs_owner_info	*oinfo,
+	bool				unwritten)
+{
+	switch (op) {
+	case XFS_RMAP_ALLOC:
+	case XFS_RMAP_MAP:
+		return xfs_rmap_map(rcur, bno, len, unwritten, oinfo);
+	case XFS_RMAP_MAP_SHARED:
+		return xfs_rmap_map_shared(rcur, bno, len, unwritten, oinfo);
+	case XFS_RMAP_FREE:
+	case XFS_RMAP_UNMAP:
+		return xfs_rmap_unmap(rcur, bno, len, unwritten, oinfo);
+	case XFS_RMAP_UNMAP_SHARED:
+		return xfs_rmap_unmap_shared(rcur, bno, len, unwritten, oinfo);
+	case XFS_RMAP_CONVERT:
+		return xfs_rmap_convert(rcur, bno, len, !unwritten, oinfo);
+	case XFS_RMAP_CONVERT_SHARED:
+		return xfs_rmap_convert_shared(rcur, bno, len, !unwritten,
+				oinfo);
+	default:
+		ASSERT(0);
+		return -EFSCORRUPTED;
+	}
+}
+
 /*
  * Process one of the deferred rmap operations.  We pass back the
  * btree cursor to maintain our lock on the rmapbt between calls.
@@ -2578,39 +2682,14 @@ xfs_rmap_finish_one(
 	unwritten = ri->ri_bmap.br_state == XFS_EXT_UNWRITTEN;
 	bno = XFS_FSB_TO_AGBNO(rcur->bc_mp, ri->ri_bmap.br_startblock);
 
-	switch (ri->ri_type) {
-	case XFS_RMAP_ALLOC:
-	case XFS_RMAP_MAP:
-		error = xfs_rmap_map(rcur, bno, ri->ri_bmap.br_blockcount,
-				unwritten, &oinfo);
-		break;
-	case XFS_RMAP_MAP_SHARED:
-		error = xfs_rmap_map_shared(rcur, bno,
-				ri->ri_bmap.br_blockcount, unwritten, &oinfo);
-		break;
-	case XFS_RMAP_FREE:
-	case XFS_RMAP_UNMAP:
-		error = xfs_rmap_unmap(rcur, bno, ri->ri_bmap.br_blockcount,
-				unwritten, &oinfo);
-		break;
-	case XFS_RMAP_UNMAP_SHARED:
-		error = xfs_rmap_unmap_shared(rcur, bno,
-				ri->ri_bmap.br_blockcount, unwritten, &oinfo);
-		break;
-	case XFS_RMAP_CONVERT:
-		error = xfs_rmap_convert(rcur, bno, ri->ri_bmap.br_blockcount,
-				!unwritten, &oinfo);
-		break;
-	case XFS_RMAP_CONVERT_SHARED:
-		error = xfs_rmap_convert_shared(rcur, bno,
-				ri->ri_bmap.br_blockcount, !unwritten, &oinfo);
-		break;
-	default:
-		ASSERT(0);
-		error = -EFSCORRUPTED;
-	}
+	error = __xfs_rmap_finish_intent(rcur, ri->ri_type, bno,
+			ri->ri_bmap.br_blockcount, &oinfo, unwritten);
+	if (error)
+		return error;
 
-	return error;
+	xfs_rmap_update_hook(tp, ri->ri_pag, ri->ri_type, bno,
+			ri->ri_bmap.br_blockcount, unwritten, &oinfo);
+	return 0;
 }
 
 /*