git: c8e9bad25a43 - stable/15 - vm_fault: add helper vm_fault_can_cow_rename()

The branch stable/15 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=c8e9bad25a439d8952a0e5b5e42b5b14d8102e25

commit c8e9bad25a439d8952a0e5b5e42b5b14d8102e25
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-07-24 10:47:52 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2025-10-11 05:08:13 +0000

    vm_fault: add helper vm_fault_can_cow_rename()
    
    (cherry picked from commit 3f05bbdbd80f2eefb647e595dc73e80d6186d6a5)
---
 sys/vm/vm_fault.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index 0039a8786387..fff6558fba7e 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -1003,6 +1003,16 @@ vm_fault_relookup(struct faultstate *fs)
 	return (KERN_SUCCESS);
 }
 
+static bool
+vm_fault_can_cow_rename(struct faultstate *fs)
+{
+	return (
+	    /* Only one shadow object and no other refs. */
+	    fs->object->shadow_count == 1 && fs->object->ref_count == 1 &&
+	    /* No other ways to look the object up. */
+	    fs->object->handle == NULL && (fs->object->flags & OBJ_ANON) != 0);
+}
+
 static void
 vm_fault_cow(struct faultstate *fs)
 {
@@ -1020,15 +1030,7 @@ vm_fault_cow(struct faultstate *fs)
 	 * object so that it will go out to swap when needed.
 	 */
 	is_first_object_locked = false;
-	if (
-	    /*
-	     * Only one shadow object and no other refs.
-	     */
-	    fs->object->shadow_count == 1 && fs->object->ref_count == 1 &&
-	    /*
-	     * No other ways to look the object up
-	     */
-	    fs->object->handle == NULL && (fs->object->flags & OBJ_ANON) != 0 &&
+	if (vm_fault_can_cow_rename(fs) &&
 	    /*
 	     * We don't chase down the shadow chain and we can acquire locks.
 	     */