The branch main has been updated by dougm:
URL:
https://cgit.FreeBSD.org/src/commit/?id=420e2f8a74df4be1237244a4ef222d2ceae6823d
commit 420e2f8a74df4be1237244a4ef222d2ceae6823d
Author: Doug Moore <do...@freebsd.org>
AuthorDate: 2025-03-02 08:13:24 +0000
Commit: Doug Moore <do...@freebsd.org>
CommitDate: 2025-03-02 08:13:24 +0000
vnode_pager: simplify loop, avoid overflow
Filling in read-behind pages in vnode_pager_generic_getpages() is made
very slightly simpler here, by avoiding overflowing the startpindex
variable and then avoiding an extra test in the allocation loop that
handles the overflow case.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D49200
---
sys/vm/vnode_pager.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index d5d312b3cf71..69509fe8948a 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -1045,18 +1045,13 @@ vnode_pager_generic_getpages(struct vnode *vp,
vm_page_t *m, int count,
vm_page_t mpred, p;
VM_OBJECT_WLOCK(object);
- startpindex = m[0]->pindex - rbehind;
- if ((mpred = TAILQ_PREV(m[0], pglist, listq)) != NULL &&
- mpred->pindex >= startpindex)
- startpindex = mpred->pindex + 1;
+ tpindex = m[0]->pindex;
+ startpindex = MAX(tpindex, rbehind) - rbehind;
+ if ((mpred = TAILQ_PREV(m[0], pglist, listq)) != NULL)
+ startpindex = MAX(startpindex, mpred->pindex + 1);
- /*
- * tpindex is unsigned; beware of numeric underflow.
- * Stepping backward from pindex, mpred doesn't change.
- */
- for (tpindex = m[0]->pindex - 1;
- tpindex >= startpindex && tpindex < m[0]->pindex;
- tpindex--, i++) {
+ /* Stepping backward from pindex, mpred doesn't change. */
+ for (; tpindex-- > startpindex; i++) {
p = vm_page_alloc_after(object, tpindex,
VM_ALLOC_NORMAL, mpred);
if (p == NULL) {
