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vfs: factor out avoidable branches in _vn_lock

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This commit is contained in:
Mateusz Guzik 2020-01-05 01:00:11 +00:00
parent 8dbc63520c
commit 7e2ea5772b
1 changed files with 40 additions and 15 deletions
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55
sys/kern/vfs_vnops.c
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@ -1564,28 +1564,53 @@ vn_poll(struct file *fp, int events, struct ucred *active_cred,
* Acquire the requested lock and then check for validity. LK_RETRY
* permits vn_lock to return doomed vnodes.
*/
static int __noinline
_vn_lock_fallback(struct vnode *vp, int flags, char *file, int line, int error)
{
KASSERT((flags & LK_RETRY) == 0 || error == 0,
("vn_lock: error %d incompatible with flags %#x", error, flags));
if (error == 0)
VNASSERT(VN_IS_DOOMED(vp), vp, ("vnode not doomed"));
if ((flags & LK_RETRY) == 0) {
if (error == 0) {
VOP_UNLOCK(vp);
error = ENOENT;
}
return (error);
}
/*
* LK_RETRY case.
*
* Nothing to do if we got the lock.
*/
if (error == 0)
return (0);
/*
* Interlock was dropped by the call in _vn_lock.
*/
flags &= ~LK_INTERLOCK;
do {
error = VOP_LOCK1(vp, flags, file, line);
} while (error != 0);
return (0);
}
int
_vn_lock(struct vnode *vp, int flags, char *file, int line)
{
int error;
VNASSERT((flags & LK_TYPE_MASK) != 0, vp,
("vn_lock: no locktype"));
VNASSERT((flags & LK_TYPE_MASK) != 0, vp, ("vn_lock: no locktype"));
VNASSERT(vp->v_holdcnt != 0, vp, ("vn_lock: zero hold count"));
retry:
error = VOP_LOCK1(vp, flags, file, line);
flags &= ~LK_INTERLOCK; /* Interlock is always dropped. */
KASSERT((flags & LK_RETRY) == 0 || error == 0,
("vn_lock: error %d incompatible with flags %#x", error, flags));
if ((flags & LK_RETRY) == 0) {
if (error == 0 && VN_IS_DOOMED(vp)) {
VOP_UNLOCK(vp);
error = ENOENT;
}
} else if (error != 0)
goto retry;
return (error);
if (__predict_false(error != 0 || VN_IS_DOOMED(vp)))
return (_vn_lock_fallback(vp, flags, file, line, error));
return (0);
}
/*