[src/trunk]: src/sys/miscfs/genfs genfs_do_directio: acquire the lock of page...

[rmind <rmind%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/25aa6371b95d
branches:  trunk
changeset: 769125:25aa6371b95d
user:      rmind <rmind%NetBSD.org@localhost>
date:      Wed Aug 31 22:16:54 2011 +0000

description:
genfs_do_directio: acquire the lock of page owner for now and fix PR/45177.
Will be revisited to avoid locking dance and be more efficient, e.g. we can
use unmanaged-mapping by allocating with colouring in mind.

diffstat:

 sys/miscfs/genfs/genfs_io.c |  41 +++++++++++++++++++++++++++++++++--------
 1 files changed, 33 insertions(+), 8 deletions(-)

diffs (85 lines):

diff -r 8746dd6f32ca -r 25aa6371b95d sys/miscfs/genfs/genfs_io.c
--- a/sys/miscfs/genfs/genfs_io.c       Wed Aug 31 22:05:57 2011 +0000
+++ b/sys/miscfs/genfs/genfs_io.c       Wed Aug 31 22:16:54 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: genfs_io.c,v 1.49 2011/06/12 03:35:58 rmind Exp $      */
+/*     $NetBSD: genfs_io.c,v 1.50 2011/08/31 22:16:54 rmind Exp $      */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.49 2011/06/12 03:35:58 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.50 2011/08/31 22:16:54 rmind Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -1748,6 +1748,8 @@
        int error, rv, poff, koff;
        const int pgoflags = PGO_CLEANIT | PGO_SYNCIO | PGO_JOURNALLOCKED |
                (rw == UIO_WRITE ? PGO_FREE : 0);
+       struct vm_page *pg;
+       kmutex_t *slock;
 
        /*
         * For writes, verify that this range of the file already has fully
@@ -1804,13 +1806,22 @@
        kva = uvm_km_alloc(kernel_map, klen, 0,
                           UVM_KMF_VAONLY | UVM_KMF_WAITVA);
        puva = trunc_page(uva);
-       mutex_enter(vp->v_interlock);
        for (poff = 0; poff < klen; poff += PAGE_SIZE) {
                rv = pmap_extract(upm, puva + poff, &pa);
                KASSERT(rv);
+               pg = PHYS_TO_VM_PAGE(pa);
+
+retry1:                /* XXX: Rework to not use managed-mappings.. */
+               mutex_enter(&uvm_pageqlock);
+               slock = uvmpd_trylockowner(pg);
+               mutex_exit(&uvm_pageqlock);
+               if (slock == NULL) {
+                       kpause("gendiolk", false, 1, slock);
+                       goto retry1;
+               }
                pmap_enter(kpm, kva + poff, pa, prot, prot | PMAP_WIRED);
+               mutex_exit(slock);
        }
-       mutex_exit(vp->v_interlock);
        pmap_update(kpm);
 
        /*
@@ -1825,9 +1836,24 @@
         * Tear down the kernel mapping.
         */
 
-       mutex_enter(vp->v_interlock);
-       pmap_remove(kpm, kva, kva + klen);
-       mutex_exit(vp->v_interlock);
+       for (koff = 0; koff < klen; koff += PAGE_SIZE) {
+               vaddr_t sva = kva + koff;
+
+               rv = pmap_extract(kpm, sva, &pa);
+               KASSERT(rv);
+               pg = PHYS_TO_VM_PAGE(pa);
+
+retry2:                /* XXX: Rework to not use managed-mappings.. */
+               mutex_enter(&uvm_pageqlock);
+               slock = uvmpd_trylockowner(pg);
+               mutex_exit(&uvm_pageqlock);
+               if (slock == NULL) {
+                       kpause("gendiolk", false, 1, slock);
+                       goto retry2;
+               }
+               pmap_remove(kpm, sva, sva + PAGE_SIZE);
+               mutex_exit(slock);
+       }
        pmap_update(kpm);
        uvm_km_free(kernel_map, kva, klen, UVM_KMF_VAONLY);
 
@@ -1838,4 +1864,3 @@
        uvm_vsunlock(vs, (void *)uva, len);
        return error;
 }
-