[src/trunk]: src/sys/miscfs/genfs in genfs_getpages(), mark the vnode dirty (...

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

details:   https://anonhg.NetBSD.org/src/rev/47f7e4c71272
branches:  trunk
changeset: 756959:47f7e4c71272
user:      chs <chs%NetBSD.org@localhost>
date:      Sun Aug 08 18:17:11 2010 +0000

description:
in genfs_getpages(), mark the vnode dirty (ie. add to syncer worklist
and set VI_WRMAPDIRTY) after we have busied the pages rather than
before.  this prevents other threads calling genfs_do_putpages() from
marking the vnode clean again while we're in the process of creating
new writable mappings, since such threads will wait for the page(s) to
become unbusy before proceeding.
fixes the problem recently reported by hannken@ on tech-kern.

diffstat:

 sys/miscfs/genfs/genfs_io.c |  58 ++++++++++++++++++++++++++++----------------
 1 files changed, 37 insertions(+), 21 deletions(-)

diffs (139 lines):

diff -r c85cee1c4e70 -r 47f7e4c71272 sys/miscfs/genfs/genfs_io.c
--- a/sys/miscfs/genfs/genfs_io.c       Sun Aug 08 18:13:54 2010 +0000
+++ b/sys/miscfs/genfs/genfs_io.c       Sun Aug 08 18:17:11 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: genfs_io.c,v 1.37 2010/07/29 10:54:50 hannken Exp $    */
+/*     $NetBSD: genfs_io.c,v 1.38 2010/08/08 18:17:11 chs Exp $        */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.37 2010/07/29 10:54:50 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.38 2010/08/08 18:17:11 chs Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -62,11 +62,12 @@
 
 static int genfs_do_io(struct vnode *, off_t, vaddr_t, size_t, int, enum uio_rw,
     void (*)(struct buf *));
-static inline void genfs_rel_pages(struct vm_page **, int);
+static void genfs_rel_pages(struct vm_page **, int);
+static void genfs_markdirty(struct vnode *);
 
 int genfs_maxdio = MAXPHYS;
 
-static inline void
+static void
 genfs_rel_pages(struct vm_page **pgs, int npages)
 {
        int i;
@@ -85,6 +86,21 @@
        mutex_exit(&uvm_pageqlock);
 }
 
+static void
+genfs_markdirty(struct vnode *vp)
+{
+       struct genfs_node * const gp = VTOG(vp);
+
+       KASSERT(mutex_owned(&vp->v_interlock));
+       gp->g_dirtygen++;
+       if ((vp->v_iflag & VI_ONWORKLST) == 0) {
+               vn_syncer_add_to_worklist(vp, filedelay);
+       }
+       if ((vp->v_iflag & (VI_WRMAP|VI_WRMAPDIRTY)) == VI_WRMAP) {
+               vp->v_iflag |= VI_WRMAPDIRTY;
+       }
+}
+
 /*
  * generic VM getpages routine.
  * Return PG_BUSY pages for the given range,
@@ -186,16 +202,6 @@
                }
        }
 
-       if (memwrite) {
-               gp->g_dirtygen++;
-               if ((vp->v_iflag & VI_ONWORKLST) == 0) {
-                       vn_syncer_add_to_worklist(vp, filedelay);
-               }
-               if ((vp->v_iflag & (VI_WRMAP|VI_WRMAPDIRTY)) == VI_WRMAP) {
-                       vp->v_iflag |= VI_WRMAPDIRTY;
-               }
-       }
-
        /*
         * For PGO_LOCKED requests, just return whatever's in memory.
         */
@@ -236,6 +242,9 @@
                        genfs_node_unlock(vp);
                }
                error = (ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0);
+               if (error == 0 && memwrite) {
+                       genfs_markdirty(vp);
+               }
                goto out_err;
        }
        mutex_exit(&uobj->vmobjlock);
@@ -696,6 +705,9 @@
                }
        }
        mutex_exit(&uvm_pageqlock);
+       if (memwrite) {
+               genfs_markdirty(vp);
+       }
        mutex_exit(&uobj->vmobjlock);
        if (ap->a_m != NULL) {
                memcpy(ap->a_m, &pgs[ridx],
@@ -708,7 +720,7 @@
 out_err:
        if (has_trans)
                fstrans_done(vp->v_mount);
-       return (error);
+       return error;
 }
 
 /*
@@ -1467,18 +1479,19 @@
        orignpages = *ap->a_count;
        pgs = ap->a_m;
 
-       if (memwrite && (vp->v_iflag & VI_ONWORKLST) == 0) {
-               vn_syncer_add_to_worklist(vp, filedelay);
-       }
        if (ap->a_flags & PGO_LOCKED) {
                uvn_findpages(uobj, origoffset, ap->a_count, ap->a_m,
                    UFP_NOWAIT|UFP_NOALLOC| (memwrite ? UFP_NORDONLY : 0));
 
-               return (ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0);
+               error = ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0;
+               if (error == 0 && memwrite) {
+                       genfs_markdirty(vp);
+               }
+               return error;
        }
        if (origoffset + (ap->a_centeridx << PAGE_SHIFT) >= vp->v_size) {
                mutex_exit(&uobj->vmobjlock);
-               return (EINVAL);
+               return EINVAL;
        }
        if ((ap->a_flags & PGO_SYNCIO) == 0) {
                mutex_exit(&uobj->vmobjlock);
@@ -1527,8 +1540,11 @@
                uvm_page_unbusy(pgs, npages);
        }
        mutex_exit(&uvm_pageqlock);
+       if (error == 0 && memwrite) {
+               genfs_markdirty(vp);
+       }
        mutex_exit(&uobj->vmobjlock);
-       return (error);
+       return error;
 }
 
 int