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Locking a layer vnode is racy as it may become reclaimed before

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calling the operation on the lower vnode.

Replace vi_lock with a rw_obj and change layered file systems
to share the lock with the lower vnode.

Layered file systems now use genfs_lock()/_unlock/_islocked().

Welcome to 7.99.67
This commit is contained in:
hannken 2017-03-30 09:16:52 +00:00
parent 799c5cfefa
commit d0dc55acf0
11 changed files with 65 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
sys/kern/vfs_vnode.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vfs_vnode.c,v 1.80 2017/03/30 09:15:51 hannken Exp $ */
/* $NetBSD: vfs_vnode.c,v 1.81 2017/03/30 09:16:52 hannken Exp $ */
/*-
* Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@ -156,7 +156,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.80 2017/03/30 09:15:51 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.81 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@ -415,6 +415,21 @@ vnis_marker(vnode_t *vp)
return (VNODE_TO_VIMPL(vp)->vi_state == VS_MARKER);
}
/*
* Set vnode to share another vnodes lock.
*/
void
vshare_lock(vnode_t *vp, vnode_t *src_vp)
{
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
vnode_impl_t *src_vip = VNODE_TO_VIMPL(src_vp);
krwlock_t *oldlock = vip->vi_lock;
rw_obj_hold(src_vip->vi_lock);
vip->vi_lock = src_vip->vi_lock;
rw_obj_free(oldlock);
}
/*
* Return the lru list this node should be on.
*/
@ -1066,7 +1081,7 @@ vcache_alloc(void)
vip = pool_cache_get(vcache_pool, PR_WAITOK);
memset(vip, 0, sizeof(*vip));
rw_init(&vip->vi_lock);
vip->vi_lock = rw_obj_alloc();
/* SLIST_INIT(&vip->vi_hash); */
/* LIST_INIT(&vip->vi_nclist); */
/* LIST_INIT(&vip->vi_dnclist); */
@ -1128,7 +1143,7 @@ vcache_free(vnode_impl_t *vip)
if (vp->v_type == VBLK || vp->v_type == VCHR)
spec_node_destroy(vp);
rw_destroy(&vip->vi_lock);
rw_obj_free(vip->vi_lock);
uvm_obj_destroy(&vp->v_uobj, true);
cv_destroy(&vp->v_cv);
pool_cache_put(vcache_pool, vip);

32
sys/miscfs/genfs/genfs_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: genfs_vnops.c,v 1.193 2017/01/11 09:08:59 hannken Exp $ */
/* $NetBSD: genfs_vnops.c,v 1.194 2017/03/30 09:16:52 hannken Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -57,7 +57,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.193 2017/01/11 09:08:59 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.194 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -295,7 +295,7 @@ genfs_deadlock(void *v)
op = (ISSET(flags, LK_EXCLUSIVE) ? RW_WRITER : RW_READER);
if (ISSET(flags, LK_NOWAIT)) {
if (! rw_tryenter(&vip->vi_lock, op))
if (! rw_tryenter(vip->vi_lock, op))
return EBUSY;
if (mutex_tryenter(vp->v_interlock)) {
error = vdead_check(vp, VDEAD_NOWAIT);
@ -305,25 +305,25 @@ genfs_deadlock(void *v)
} else
error = EBUSY;
if (error)
rw_exit(&vip->vi_lock);
rw_exit(vip->vi_lock);
return error;
}
rw_enter(&vip->vi_lock, op);
rw_enter(vip->vi_lock, op);
mutex_enter(vp->v_interlock);
error = vdead_check(vp, VDEAD_NOWAIT);
if (error == EBUSY) {
rw_exit(&vip->vi_lock);
rw_exit(vip->vi_lock);
error = vdead_check(vp, 0);
KASSERT(error == ENOENT);
mutex_exit(vp->v_interlock);
rw_enter(&vip->vi_lock, op);
rw_enter(vip->vi_lock, op);
mutex_enter(vp->v_interlock);
}
KASSERT(error == ENOENT);
mutex_exit(vp->v_interlock);
if (! ISSET(flags, LK_RETRY)) {
rw_exit(&vip->vi_lock);
rw_exit(vip->vi_lock);
return ENOENT;
}
return 0;
@ -341,7 +341,7 @@ genfs_deadunlock(void *v)
vnode_t *vp = ap->a_vp;
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
rw_exit(&vip->vi_lock);
rw_exit(vip->vi_lock);
return 0;
}
@ -367,7 +367,7 @@ genfs_lock(void *v)
if (ISSET(flags, LK_NOWAIT)) {
if (fstrans_start_nowait(mp, FSTRANS_SHARED))
return EBUSY;
if (! rw_tryenter(&vip->vi_lock, op)) {
if (! rw_tryenter(vip->vi_lock, op)) {
fstrans_done(mp);
return EBUSY;
}
@ -377,18 +377,18 @@ genfs_lock(void *v)
} else
error = EBUSY;
if (error) {
rw_exit(&vip->vi_lock);
rw_exit(vip->vi_lock);
fstrans_done(mp);
}
return error;
}
fstrans_start(mp, FSTRANS_SHARED);
rw_enter(&vip->vi_lock, op);
rw_enter(vip->vi_lock, op);
mutex_enter(vp->v_interlock);
error = vdead_check(vp, VDEAD_NOWAIT);
if (error) {
rw_exit(&vip->vi_lock);
rw_exit(vip->vi_lock);
fstrans_done(mp);
error = vdead_check(vp, 0);
KASSERT(error == ENOENT);
@ -410,7 +410,7 @@ genfs_unlock(void *v)
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
struct mount *mp = vp->v_mount;
rw_exit(&vip->vi_lock);
rw_exit(vip->vi_lock);
fstrans_done(mp);
return 0;
@ -428,10 +428,10 @@ genfs_islocked(void *v)
vnode_t *vp = ap->a_vp;
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
if (rw_write_held(&vip->vi_lock))
if (rw_write_held(vip->vi_lock))
return LK_EXCLUSIVE;
if (rw_read_held(&vip->vi_lock))
if (rw_read_held(vip->vi_lock))
return LK_SHARED;
return 0;

6
sys/miscfs/genfs/layer_extern.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: layer_extern.h,v 1.38 2017/02/17 08:31:25 hannken Exp $ */
/* $NetBSD: layer_extern.h,v 1.39 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@ -99,7 +99,6 @@ int layer_bypass(void *);
int layer_getattr(void *);
int layer_inactive(void *);
int layer_reclaim(void *);
int layer_lock(void *);
int layer_print(void *);
int layer_bmap(void *);
int layer_fsync(void *);
@ -114,5 +113,8 @@ int layer_revoke(void *);
int layer_rmdir(void *);
int layer_getpages(void *);
int layer_putpages(void *);
#define layer_lock genfs_lock
#define layer_unlock genfs_unlock
#define layer_islocked genfs_islocked
#endif /* _MISCFS_GENFS_LAYER_EXTERN_H_ */

7
sys/miscfs/genfs/layer_vfsops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: layer_vfsops.c,v 1.47 2017/02/17 08:31:25 hannken Exp $ */
/* $NetBSD: layer_vfsops.c,v 1.48 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@ -74,7 +74,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: layer_vfsops.c,v 1.47 2017/02/17 08:31:25 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: layer_vfsops.c,v 1.48 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/sysctl.h>
@ -223,6 +223,9 @@ layerfs_loadvnode(struct mount *mp, struct vnode *vp,
mutex_obj_hold(lowervp->v_interlock);
uvm_obj_setlock(&vp->v_uobj, lowervp->v_interlock);
/* Share the lock with the lower node. */
vshare_lock(vp, lowervp);
vp->v_tag = lmp->layerm_tag;
vp->v_type = lowervp->v_type;
vp->v_op = lmp->layerm_vnodeop_p;

46
sys/miscfs/genfs/layer_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: layer_vnops.c,v 1.60 2017/01/27 10:47:13 hannken Exp $ */
/* $NetBSD: layer_vnops.c,v 1.61 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@ -170,7 +170,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: layer_vnops.c,v 1.60 2017/01/27 10:47:13 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: layer_vnops.c,v 1.61 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -743,48 +743,6 @@ layer_reclaim(void *v)
return 0;
}
int
layer_lock(void *v)
{
struct vop_lock_args /* {
struct vnode *a_vp;
int a_flags;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
struct vnode *lowervp = LAYERVPTOLOWERVP(vp);
int flags = ap->a_flags;
int error;
if (ISSET(flags, LK_NOWAIT)) {
error = VOP_LOCK(lowervp, flags);
if (error)
return error;
if (mutex_tryenter(vp->v_interlock)) {
error = vdead_check(vp, VDEAD_NOWAIT);
mutex_exit(vp->v_interlock);
} else
error = EBUSY;
if (error)
VOP_UNLOCK(lowervp);
return error;
}
error = VOP_LOCK(lowervp, flags);
if (error)
return error;
mutex_enter(vp->v_interlock);
error = vdead_check(vp, VDEAD_NOWAIT);
if (error) {
VOP_UNLOCK(lowervp);
error = vdead_check(vp, 0);
KASSERT(error == ENOENT);
}
mutex_exit(vp->v_interlock);
return error;
}
/*
* We just feed the returned vnode up to the caller - there's no need
* to build a layer node on top of the node on which we're going to do

6
sys/miscfs/nullfs/null_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: null_vnops.c,v 1.40 2017/01/27 10:47:13 hannken Exp $ */
/* $NetBSD: null_vnops.c,v 1.41 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@ -80,7 +80,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: null_vnops.c,v 1.40 2017/01/27 10:47:13 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: null_vnops.c,v 1.41 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -107,6 +107,8 @@ const struct vnodeopv_entry_desc null_vnodeop_entries[] = {
{ &vop_inactive_desc, layer_inactive },
{ &vop_reclaim_desc, layer_reclaim },
{ &vop_lock_desc, layer_lock },
{ &vop_unlock_desc, layer_unlock },
{ &vop_islocked_desc, layer_islocked },
{ &vop_print_desc, layer_print },
{ &vop_remove_desc, layer_remove },
{ &vop_rename_desc, layer_rename },

8
sys/miscfs/overlay/overlay_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: overlay_vnops.c,v 1.22 2017/01/27 10:47:13 hannken Exp $ */
/* $NetBSD: overlay_vnops.c,v 1.23 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999, 2000 National Aeronautics & Space Administration
@ -67,7 +67,7 @@
*
* Ancestors:
* @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92
* $Id: overlay_vnops.c,v 1.22 2017/01/27 10:47:13 hannken Exp $
* $Id: overlay_vnops.c,v 1.23 2017/03/30 09:16:52 hannken Exp $
* ...and...
* @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
*/
@ -126,7 +126,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: overlay_vnops.c,v 1.22 2017/01/27 10:47:13 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: overlay_vnops.c,v 1.23 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -155,6 +155,8 @@ const struct vnodeopv_entry_desc overlay_vnodeop_entries[] = {
{ &vop_inactive_desc, layer_inactive },
{ &vop_reclaim_desc, layer_reclaim },
{ &vop_lock_desc, layer_lock },
{ &vop_unlock_desc, layer_unlock },
{ &vop_islocked_desc, layer_islocked },
{ &vop_print_desc, layer_print },
{ &vop_remove_desc, layer_remove },
{ &vop_rename_desc, layer_rename },

6
sys/miscfs/umapfs/umap_vnops.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: umap_vnops.c,v 1.58 2017/01/27 10:47:13 hannken Exp $ */
/* $NetBSD: umap_vnops.c,v 1.59 2017/03/30 09:16:53 hannken Exp $ */
/*
* Copyright (c) 1992, 1993
@ -39,7 +39,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: umap_vnops.c,v 1.58 2017/01/27 10:47:13 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: umap_vnops.c,v 1.59 2017/03/30 09:16:53 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -89,6 +89,8 @@ const struct vnodeopv_entry_desc umap_vnodeop_entries[] = {
{ &vop_inactive_desc, layer_inactive },
{ &vop_reclaim_desc, layer_reclaim },
{ &vop_lock_desc, layer_lock },
{ &vop_unlock_desc, layer_unlock },
{ &vop_islocked_desc, layer_islocked },
{ &vop_open_desc, layer_open },
{ &vop_close_desc, layer_close },
{ &vop_setattr_desc, layer_setattr },

4
sys/sys/param.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: param.h,v 1.533 2017/03/14 09:04:16 ozaki-r Exp $ */
/* $NetBSD: param.h,v 1.534 2017/03/30 09:16:53 hannken Exp $ */
/*-
* Copyright (c) 1982, 1986, 1989, 1993
@ -67,7 +67,7 @@
* 2.99.9 (299000900)
*/
#define __NetBSD_Version__ 799006600 /* NetBSD 7.99.66 */
#define __NetBSD_Version__ 799006700 /* NetBSD 7.99.67 */
#define __NetBSD_Prereq__(M,m,p) (((((M) * 100000000) + \
(m) * 1000000) + (p) * 100) <= __NetBSD_Version__)

3
sys/sys/vnode.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: vnode.h,v 1.274 2017/02/17 08:30:00 hannken Exp $ */
/* $NetBSD: vnode.h,v 1.275 2017/03/30 09:16:53 hannken Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -516,6 +516,7 @@ bool vrecycle(struct vnode *);
void vrele(struct vnode *);
void vrele_async(struct vnode *);
void vrele_flush(struct mount *);
void vshare_lock(vnode_t *, vnode_t *);
int vtruncbuf(struct vnode *, daddr_t, bool, int);
void vwakeup(struct buf *);
int vdead_check(struct vnode *, int);

4
sys/sys/vnode_impl.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: vnode_impl.h,v 1.12 2017/03/18 05:55:12 riastradh Exp $ */
/* $NetBSD: vnode_impl.h,v 1.13 2017/03/30 09:16:53 hannken Exp $ */
/*-
* Copyright (c) 2016 The NetBSD Foundation, Inc.
@ -76,7 +76,7 @@ struct vnode_impl {
TAILQ_ENTRY(vnode_impl) vi_synclist; /* s: vnodes with dirty bufs */
TAILQ_ENTRY(vnode_impl) vi_mntvnodes; /* m: vnodes for mount point */
SLIST_ENTRY(vnode_impl) vi_hash; /* c: vnode cache list */
krwlock_t vi_lock; /* -: lock for this vnode */
krwlock_t *vi_lock; /* -: lock for this vnode */
struct vcache_key vi_key; /* c: vnode cache key */
};
typedef struct vnode_impl vnode_impl_t;