Author: kib
Date: Wed Aug 10 12:11:11 2016
New Revision: 303905
URL: https://svnweb.freebsd.org/changeset/base/303905
Log:
MFC r303448:
Do not delegate a work to geom event thread which can be done inline.
MFC r303703:
Explain why swapgeom_close_ev() is delegated.
Approved by: re (gjb)
Modified:
stable/11/sys/vm/swap_pager.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/vm/swap_pager.c
==============================================================================
--- stable/11/sys/vm/swap_pager.c Wed Aug 10 10:36:11 2016
(r303904)
+++ stable/11/sys/vm/swap_pager.c Wed Aug 10 12:11:11 2016
(r303905)
@@ -395,7 +395,7 @@ SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG
static void swp_sizecheck(void);
static void swp_pager_async_iodone(struct buf *bp);
-static int swapongeom(struct thread *, struct vnode *);
+static int swapongeom(struct vnode *);
static int swaponvp(struct thread *, struct vnode *, u_long);
static int swapoff_one(struct swdevt *sp, struct ucred *cred);
@@ -2019,7 +2019,7 @@ sys_swapon(struct thread *td, struct swa
vp = nd.ni_vp;
if (vn_isdisk(vp, &error)) {
- error = swapongeom(td, vp);
+ error = swapongeom(vp);
} else if (vp->v_type == VREG &&
(vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
(error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) {
@@ -2431,8 +2431,9 @@ swapgeom_acquire(struct g_consumer *cp)
}
/*
- * Remove a reference from the g_consumer. Post a close event if
- * all references go away.
+ * Remove a reference from the g_consumer. Post a close event if all
+ * references go away, since the function might be called from the
+ * biodone context.
*/
static void
swapgeom_release(struct g_consumer *cp, struct swdevt *sp)
@@ -2555,22 +2556,19 @@ swapgeom_close(struct thread *td, struct
cp = sw->sw_id;
sw->sw_id = NULL;
mtx_unlock(&sw_dev_mtx);
- /* XXX: direct call when Giant untangled */
+
+ /*
+ * swapgeom_close() may be called from the biodone context,
+ * where we cannot perform topology changes. Delegate the
+ * work to the events thread.
+ */
if (cp != NULL)
g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL);
}
-
-struct swh0h0 {
- struct cdev *dev;
- struct vnode *vp;
- int error;
-};
-
-static void
-swapongeom_ev(void *arg, int flags)
+static int
+swapongeom_locked(struct cdev *dev, struct vnode *vp)
{
- struct swh0h0 *swh;
struct g_provider *pp;
struct g_consumer *cp;
static struct g_geom *gp;
@@ -2578,20 +2576,15 @@ swapongeom_ev(void *arg, int flags)
u_long nblks;
int error;
- swh = arg;
- swh->error = 0;
- pp = g_dev_getprovider(swh->dev);
- if (pp == NULL) {
- swh->error = ENODEV;
- return;
- }
+ pp = g_dev_getprovider(dev);
+ if (pp == NULL)
+ return (ENODEV);
mtx_lock(&sw_dev_mtx);
TAILQ_FOREACH(sp, &swtailq, sw_list) {
cp = sp->sw_id;
if (cp != NULL && cp->provider == pp) {
mtx_unlock(&sw_dev_mtx);
- swh->error = EBUSY;
- return;
+ return (EBUSY);
}
}
mtx_unlock(&sw_dev_mtx);
@@ -2608,34 +2601,31 @@ swapongeom_ev(void *arg, int flags)
* set an exclusive count :-(
*/
error = g_access(cp, 1, 1, 0);
- if (error) {
+ if (error != 0) {
g_detach(cp);
g_destroy_consumer(cp);
- swh->error = error;
- return;
+ return (error);
}
nblks = pp->mediasize / DEV_BSIZE;
- swaponsomething(swh->vp, cp, nblks, swapgeom_strategy,
- swapgeom_close, dev2udev(swh->dev),
+ swaponsomething(vp, cp, nblks, swapgeom_strategy,
+ swapgeom_close, dev2udev(dev),
(pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0);
- swh->error = 0;
+ return (0);
}
static int
-swapongeom(struct thread *td, struct vnode *vp)
+swapongeom(struct vnode *vp)
{
int error;
- struct swh0h0 swh;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
-
- swh.dev = vp->v_rdev;
- swh.vp = vp;
- swh.error = 0;
- /* XXX: direct call when Giant untangled */
- error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL);
- if (!error)
- error = swh.error;
+ if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) {
+ error = ENOENT;
+ } else {
+ g_topology_lock();
+ error = swapongeom_locked(vp->v_rdev, vp);
+ g_topology_unlock();
+ }
VOP_UNLOCK(vp, 0);
return (error);
}
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