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Add vfs_hash_ref(9) function, which finds a vnode by the hash value

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and returns it referenced.

The function is similar to vfs_hash_get(9), but unlike the later,
returned vnode is not locked.  This operation cannot be requested with
the vget(9) flags.

Reviewed and tested by:	rmacklem
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2016-05-11 06:32:22 +00:00
parent 8b94864213
commit 54a33d2f97
2 changed files with 32 additions and 0 deletions
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30
sys/kern/vfs_hash.c
View File

@ -103,6 +103,36 @@ vfs_hash_get(const struct mount *mp, u_int hash, int flags, struct thread *td,
}
}
void
vfs_hash_ref(const struct mount *mp, u_int hash, struct thread *td,
struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
{
struct vnode *vp;
while (1) {
rw_rlock(&vfs_hash_lock);
LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) {
if (vp->v_hash != hash)
continue;
if (vp->v_mount != mp)
continue;
if (fn != NULL && fn(vp, arg))
continue;
vhold(vp);
rw_runlock(&vfs_hash_lock);
vref(vp);
vdrop(vp);
*vpp = vp;
return;
}
if (vp == NULL) {
rw_runlock(&vfs_hash_lock);
*vpp = NULL;
return;
}
}
}
void
vfs_hash_remove(struct vnode *vp)
{

2
sys/sys/vnode.h
View File

@ -859,6 +859,8 @@ int vfs_hash_get(const struct mount *mp, u_int hash, int flags,
u_int vfs_hash_index(struct vnode *vp);
int vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td,
struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);
void vfs_hash_ref(const struct mount *mp, u_int hash, struct thread *td,
struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);
void vfs_hash_rehash(struct vnode *vp, u_int hash);
void vfs_hash_remove(struct vnode *vp);