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vfs: keep seqc unchanged as long as the vnode is accessible via SMR

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This commit is contained in:
Mateusz Guzik 2021-01-03 08:34:08 +01:00
parent 1c55eab104
commit 33a195baf3
1 changed files with 26 additions and 2 deletions
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28
sys/kern/vfs_subr.c
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@ -108,6 +108,8 @@ static int flushbuflist(struct bufv *bufv, int flags, struct bufobj *bo,
static void syncer_shutdown(void *arg, int howto);
static int vtryrecycle(struct vnode *vp);
static void v_init_counters(struct vnode *);
static void vn_seqc_init(struct vnode *);
static void vn_seqc_write_end_free(struct vnode *vp);
static void vgonel(struct vnode *);
static bool vhold_recycle_free(struct vnode *);
static void vfs_knllock(void *arg);
@ -1719,6 +1721,7 @@ getnewvnode(const char *tag, struct mount *mp, struct vop_vector *vops,
vp->v_op = vops;
vp->v_irflag = 0;
v_init_counters(vp);
vn_seqc_init(vp);
vp->v_bufobj.bo_ops = &buf_ops_bio;
#ifdef DIAGNOSTIC
if (mp == NULL && vops != &dead_vnodeops)
@ -1787,8 +1790,7 @@ freevnode(struct vnode *vp)
/*
* Paired with vgone.
*/
vn_seqc_write_end_locked(vp);
VNPASS(vp->v_seqc_users == 0, vp);
vn_seqc_write_end_free(vp);
bo = &vp->v_bufobj;
VNASSERT(vp->v_data == NULL, vp, ("cleaned vnode isn't"));
@ -6799,6 +6801,28 @@ vn_seqc_write_end(struct vnode *vp)
VI_UNLOCK(vp);
}
/*
* Special case handling for allocating and freeing vnodes.
*
* The counter remains unchanged on free so that a doomed vnode will
* keep testing as in modify as long as it is accessible with SMR.
*/
static void
vn_seqc_init(struct vnode *vp)
{
vp->v_seqc = 0;
vp->v_seqc_users = 0;
}
static void
vn_seqc_write_end_free(struct vnode *vp)
{
VNPASS(seqc_in_modify(vp->v_seqc), vp);
VNPASS(vp->v_seqc_users == 1, vp);
}
void
vn_irflag_set_locked(struct vnode *vp, short toset)
{