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vfs: fully hold vnodes in vnlru_free_locked

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Currently the code only bumps holdcnt and clears the VI_FREE flag, not
performing actual vhold. Since the vnode is still visible elsewhere, a
potential new user can find it and incorrectly assume it is properly held.

Use vholdl instead to correctly hold the vnode. Another place recycling
(vlrureclaim) does this already.

Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D21522
This commit is contained in:
mjg 2019-09-04 19:23:18 +00:00
parent 7848664844
commit 7555f0f24e
1 changed files with 1 additions and 6 deletions
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7
sys/kern/vfs_subr.c
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@ -1102,7 +1102,6 @@ vnlru_free_locked(int count, struct vfsops *mnt_op)
("Removing vnode not on freelist"));
KASSERT((vp->v_iflag & VI_ACTIVE) == 0,
("Mangling active vnode"));
TAILQ_REMOVE(&vnode_free_list, vp, v_actfreelist);
/*
* Don't recycle if our vnode is from different type
@ -1114,7 +1113,6 @@ vnlru_free_locked(int count, struct vfsops *mnt_op)
*/
if ((mnt_op != NULL && (mp = vp->v_mount) != NULL &&
mp->mnt_op != mnt_op) || !VI_TRYLOCK(vp)) {
TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_actfreelist);
continue;
}
VNASSERT((vp->v_iflag & VI_FREE) != 0 && vp->v_holdcnt == 0,
@ -1129,11 +1127,8 @@ vnlru_free_locked(int count, struct vfsops *mnt_op)
* activating.
*/
freevnodes--;
vp->v_iflag &= ~VI_FREE;
VNODE_REFCOUNT_FENCE_REL();
refcount_acquire(&vp->v_holdcnt);
mtx_unlock(&vnode_free_list_mtx);
vholdl(vp);
VI_UNLOCK(vp);
vtryrecycle(vp);
/*