Fixed an object allocation race condition that was causing a "object
deallocated too many times" panic when using NFS. Reviewed by: John Dyson
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=9411
@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)vnode.h 8.7 (Berkeley) 2/4/94
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* $Id: vnode.h,v 1.20 1995/04/20 03:18:19 julian Exp $
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* $Id: vnode.h,v 1.21 1995/06/28 12:01:07 davidg Exp $
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*/
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#ifndef _SYS_VNODE_H_
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@ -107,16 +107,18 @@ struct vnode {
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/*
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* Vnode flags.
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*/
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#define VROOT 0x0001 /* root of its file system */
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#define VTEXT 0x0002 /* vnode is a pure text prototype */
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#define VSYSTEM 0x0004 /* vnode being used by kernel */
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#define VXLOCK 0x0100 /* vnode is locked to change underlying type */
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#define VXWANT 0x0200 /* process is waiting for vnode */
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#define VBWAIT 0x0400 /* waiting for output to complete */
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#define VALIASED 0x0800 /* vnode has an alias */
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#define VDIROP 0x1000 /* LFS: vnode is involved in a directory op */
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#define VROOT 0x0001 /* root of its file system */
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#define VTEXT 0x0002 /* vnode is a pure text prototype */
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#define VSYSTEM 0x0004 /* vnode being used by kernel */
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#define VOLOCK 0x0008 /* vnode is locked waiting for an object */
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#define VOWANT 0x0010 /* a process is waiting for VOLOCK */
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#define VXLOCK 0x0100 /* vnode is locked to change underlying type */
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#define VXWANT 0x0200 /* process is waiting for vnode */
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#define VBWAIT 0x0400 /* waiting for output to complete */
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#define VALIASED 0x0800 /* vnode has an alias */
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#define VDIROP 0x1000 /* LFS: vnode is involved in a directory op */
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#define VVMIO 0x2000 /* VMIO flag */
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#define VNINACT 0x4000 /* LFS: skip ufs_inactive() in lfs_vunref */
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#define VNINACT 0x4000 /* LFS: skip ufs_inactive() in lfs_vunref */
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#define VAGE 0x8000 /* Insert vnode at head of free list */
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/*
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@ -37,7 +37,7 @@
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* SUCH DAMAGE.
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*
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* from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
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* $Id: vnode_pager.c,v 1.40 1995/05/30 08:16:23 rgrimes Exp $
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* $Id: vnode_pager.c,v 1.41 1995/06/28 12:01:13 davidg Exp $
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*/
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/*
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@ -136,13 +136,23 @@ vnode_pager_alloc(handle, size, prot, offset)
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if (handle == NULL)
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return (NULL);
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/*
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* Vnodes keep a pointer to any associated pager so no need to lookup
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* with vm_pager_lookup.
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*/
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vp = (struct vnode *) handle;
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while ((object = vp->v_object) &&
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(object->flags & OBJ_DEAD))
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/*
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* Prevent race condition when allocating the object. This
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* can happen with NFS vnodes since the nfsnode isn't locked.
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*/
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while (vp->v_flag & VOLOCK) {
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vp->v_flag |= VOWANT;
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tsleep(vp, PVM, "vnpobj", 0);
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}
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vp->v_flag |= VOLOCK;
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/*
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* If the object is being terminated, wait for it to
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* go away.
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*/
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while (((object = vp->v_object) != NULL) && (object->flags & OBJ_DEAD))
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tsleep(object, PVM, "vadead", 0);
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pager = NULL;
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@ -154,13 +164,8 @@ vnode_pager_alloc(handle, size, prot, offset)
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* Allocate pager structures
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*/
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pager = (vm_pager_t) malloc(sizeof *pager, M_VMPAGER, M_WAITOK);
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if (pager == NULL)
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return (NULL);
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vnp = (vn_pager_t) malloc(sizeof *vnp, M_VMPGDATA, M_WAITOK);
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if (vnp == NULL) {
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free((caddr_t) pager, M_VMPAGER);
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return (NULL);
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}
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/*
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* And an object of the appropriate size
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*/
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@ -170,6 +175,15 @@ vnode_pager_alloc(handle, size, prot, offset)
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vm_object_enter(object, pager);
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object->pager = pager;
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} else {
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/*
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* The VOP_GETATTR failed...
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* Unlock, wakeup any waiters, free pagers, and exit.
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*/
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vp->v_flag &= ~VOLOCK;
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if (vp->v_flag & VOWANT) {
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vp->v_flag &= ~VOWANT;
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wakeup(vp);
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}
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free((caddr_t) vnp, M_VMPGDATA);
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free((caddr_t) pager, M_VMPAGER);
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return (NULL);
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@ -197,8 +211,15 @@ vnode_pager_alloc(handle, size, prot, offset)
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*/
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(void) vm_object_lookup(pager);
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}
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if( vp->v_type == VREG)
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if (vp->v_type == VREG)
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vp->v_flag |= VVMIO;
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vp->v_flag &= ~VOLOCK;
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if (vp->v_flag & VOWANT) {
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vp->v_flag &= ~VOWANT;
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wakeup(vp);
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}
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return (pager);
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}
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