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Do not delegate a work to geom event thread which can be done inline.

Browse Source 
In particular, swapongeom_ev() needed event thread context when swap
pager configuration was performed under Giant and geom asserted that
Giant is not owned.  Now both of the reason went away.

On the other hand, note that swpageom_release() is called from the
bio_done context, and possible close cannot be performed inline.

Also fix some minor issues.  The swapgeom() function does not use the
td argument, remove it.  Recheck that the vnode passed is still VCHR
and not reclaimed after the lock.

Reviewed by:	mav
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2016-07-28 15:57:01 +00:00
parent 2174a0c607
commit 88ad2d7b47
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=303448
1 changed files with 21 additions and 37 deletions
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58
sys/vm/swap_pager.c
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@ -395,7 +395,7 @@ SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &dmmax, 0,
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 swapon_args *uap)
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) {
@ -2560,17 +2560,9 @@ swapgeom_close(struct thread *td, struct swdevt *sw)
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 +2570,15 @@ 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 +2595,31 @@ 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);
}