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vfs: trylock in vfs_msync and refactor the func

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- use LK_NOWAIT instead of calling VOP_ISLOCKED before deciding to lock
- evaluate flags before looping over vnodes

Reviewed by:	kib
Tested by:	pho (in a larger patch, previous version)
Differential Revision:	https://reviews.freebsd.org/D23035
This commit is contained in:
Mateusz Guzik 2020-01-07 15:44:19 +00:00
parent c92fe112a7
commit b7cc9d1847
1 changed files with 24 additions and 21 deletions
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45
sys/kern/vfs_subr.c
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@ -4390,36 +4390,39 @@ vfs_msync(struct mount *mp, int flags)
{
struct vnode *vp, *mvp;
struct vm_object *obj;
struct thread *td;
int lkflags, objflags;
CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
if ((mp->mnt_kern_flag & MNTK_NOMSYNC) != 0)
return;
td = curthread;
lkflags = LK_EXCLUSIVE | LK_INTERLOCK;
if (flags != MNT_WAIT) {
lkflags |= LK_NOWAIT;
objflags = OBJPC_NOSYNC;
} else {
objflags = OBJPC_SYNC;
}
MNT_VNODE_FOREACH_ACTIVE(vp, mp, mvp) {
obj = vp->v_object;
if (obj != NULL && vm_object_mightbedirty(obj) &&
(flags == MNT_WAIT || VOP_ISLOCKED(vp) == 0)) {
if (!vget(vp,
LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK,
curthread)) {
if (vp->v_vflag & VV_NOSYNC) { /* unlinked */
vput(vp);
continue;
}
obj = vp->v_object;
if (obj != NULL) {
VM_OBJECT_WLOCK(obj);
vm_object_page_clean(obj, 0, 0,
flags == MNT_WAIT ?
OBJPC_SYNC : OBJPC_NOSYNC);
VM_OBJECT_WUNLOCK(obj);
}
vput(vp);
}
} else
if (obj == NULL || !vm_object_mightbedirty(obj)) {
VI_UNLOCK(vp);
continue;
}
if (vget(vp, lkflags, td) == 0) {
obj = vp->v_object;
if (obj != NULL && (vp->v_vflag & VV_NOSYNC) == 0) {
VM_OBJECT_WLOCK(obj);
vm_object_page_clean(obj, 0, 0, objflags);
VM_OBJECT_WUNLOCK(obj);
}
vput(vp);
}
}
}