diff options
| author | Konstantin Belousov <kib@FreeBSD.org> | 2025-08-14 03:39:05 +0000 |
|---|---|---|
| committer | Konstantin Belousov <kib@FreeBSD.org> | 2025-09-14 19:12:46 +0000 |
| commit | 5bd4c04a4e7f7bda657e6027e64675d0caf50715 (patch) | |
| tree | 91bdadff3cecfa21154de54e944f067670430a9f | |
| parent | c6b79f587f27649f90e00bc131d37bafa50ffc62 (diff) | |
vm_fault: add vm_fault_might_be_cow() helper
The helper checks that the object containing the fs->m page is not the
top object in the shadow chain.
Reviewed by: alc, markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D51474
| -rw-r--r-- | sys/vm/vm_fault.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c index a00134715171..226cf34b3ca4 100644 --- a/sys/vm/vm_fault.c +++ b/sys/vm/vm_fault.c @@ -258,6 +258,12 @@ vm_fault_unlock_vp(struct faultstate *fs) } } +static bool +vm_fault_might_be_cow(struct faultstate *fs) +{ + return (fs->object != fs->first_object); +} + static void vm_fault_deallocate(struct faultstate *fs) { @@ -265,7 +271,7 @@ vm_fault_deallocate(struct faultstate *fs) vm_fault_page_release(&fs->m_cow); vm_fault_page_release(&fs->m); vm_object_pip_wakeup(fs->object); - if (fs->object != fs->first_object) { + if (vm_fault_might_be_cow(fs)) { VM_OBJECT_WLOCK(fs->first_object); vm_fault_page_free(&fs->first_m); VM_OBJECT_WUNLOCK(fs->first_object); @@ -1005,7 +1011,7 @@ vm_fault_cow(struct faultstate *fs) { bool is_first_object_locked; - KASSERT(fs->object != fs->first_object, + KASSERT(vm_fault_might_be_cow(fs), ("source and target COW objects are identical")); /* @@ -1169,7 +1175,7 @@ vm_fault_zerofill(struct faultstate *fs) * If there's no object left, fill the page in the top * object with zeros. */ - if (fs->object != fs->first_object) { + if (vm_fault_might_be_cow(fs)) { vm_object_pip_wakeup(fs->object); fs->object = fs->first_object; fs->pindex = fs->first_pindex; @@ -1433,7 +1439,7 @@ vm_fault_busy_sleep(struct faultstate *fs, int allocflags) * likely to reclaim it. */ vm_page_aflag_set(fs->m, PGA_REFERENCED); - if (fs->object != fs->first_object) { + if (vm_fault_might_be_cow(fs)) { vm_fault_page_release(&fs->first_m); vm_object_pip_wakeup(fs->first_object); } @@ -1710,7 +1716,7 @@ found: * top-level object, we have to copy it into a new page owned by the * top-level object. */ - if (fs.object != fs.first_object) { + if (vm_fault_might_be_cow(&fs)) { /* * We only really need to copy if we want to write it. */ |