git: 54291f7d6506 - main - swap_pager: Reduce the scope of the object lock in putpages

[Alan Cox]

The branch main has been updated by alc:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=54291f7d6506e6c6087433c5bbdb2224b6cef23b

commit 54291f7d6506e6c6087433c5bbdb2224b6cef23b
Author:     Alan Cox <a...@freebsd.org>
AuthorDate: 2022-07-19 03:28:07 +0000
Commit:     Alan Cox <a...@freebsd.org>
CommitDate: 2022-07-19 03:35:49 +0000

    swap_pager: Reduce the scope of the object lock in putpages
    
    We don't need to hold the object lock while allocating swap space, so
    don't.
    
    Reviewed by:    dougm, kib, markj
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D35839
---
 sys/vm/swap_pager.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index c20360975c4b..67cc3bf017d2 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -1506,10 +1506,8 @@ swap_pager_putpages(vm_object_t object, vm_page_t *ma, 
int count,
                }
 
                /* Get a block of swap of size up to size n. */
-               VM_OBJECT_WLOCK(object);
                blk = swp_pager_getswapspace(&n);
                if (blk == SWAPBLK_NONE) {
-                       VM_OBJECT_WUNLOCK(object);
                        mtx_lock(&swbuf_mtx);
                        if (++nsw_wcount_async == 1)
                                wakeup(&nsw_wcount_async);
@@ -1518,6 +1516,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t *ma, 
int count,
                                rtvals[i + j] = VM_PAGER_FAIL;
                        continue;
                }
+               VM_OBJECT_WLOCK(object);
                for (j = 0; j < n; ++j) {
                        mreq = ma[i + j];
                        vm_page_aflag_clear(mreq, PGA_SWAP_FREE);