Author: kib
Date: Thu Feb 9 23:36:50 2017
New Revision: 313496
URL: https://svnweb.freebsd.org/changeset/base/313496
Log:
Increase a chance of devfs_close() calling d_close cdevsw method.
If a file opened over a vnode has an advisory lock set at close,
vn_closefile() acquires additional vnode use reference to prevent
freeing the vnode in vn_close(). Side effect is that for device
vnodes, devfs_close() sees that vnode reference count is greater than
one and refuses to call d_close(). Create internal version of
vn_close() which can avoid dropping the vnode reference if needed, and
use this to execute VOP_CLOSE() without acquiring a new reference.
Note that any parallel reference to the vnode would still prevent
d_close call, if the reference is not from an opened file, e.g. due to
stat(2).
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Modified:
head/sys/kern/vfs_vnops.c
Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c Thu Feb 9 23:35:57 2017 (r313495)
+++ head/sys/kern/vfs_vnops.c Thu Feb 9 23:36:50 2017 (r313496)
@@ -430,12 +430,9 @@ vn_writechk(vp)
/*
* Vnode close call
*/
-int
-vn_close(vp, flags, file_cred, td)
- register struct vnode *vp;
- int flags;
- struct ucred *file_cred;
- struct thread *td;
+static int
+vn_close1(struct vnode *vp, int flags, struct ucred *file_cred,
+ struct thread *td, bool keep_ref)
{
struct mount *mp;
int error, lock_flags;
@@ -457,11 +454,22 @@ vn_close(vp, flags, file_cred, td)
__func__, vp, vp->v_writecount);
}
error = VOP_CLOSE(vp, flags, file_cred, td);
- vput(vp);
+ if (keep_ref)
+ VOP_UNLOCK(vp, 0);
+ else
+ vput(vp);
vn_finished_write(mp);
return (error);
}
+int
+vn_close(struct vnode *vp, int flags, struct ucred *file_cred,
+ struct thread *td)
+{
+
+ return (vn_close1(vp, flags, file_cred, td, false));
+}
+
/*
* Heuristic to detect sequential operation.
*/
@@ -1573,18 +1581,15 @@ vn_closefile(struct file *fp, struct thr
struct vnode *vp;
struct flock lf;
int error;
+ bool ref;
vp = fp->f_vnode;
fp->f_ops = &badfileops;
+ ref= (fp->f_flag & FHASLOCK) != 0 && fp->f_type == DTYPE_VNODE;
- if (__predict_false((fp->f_flag & FHASLOCK) != 0) &&
- fp->f_type == DTYPE_VNODE)
- vrefact(vp);
-
- error = vn_close(vp, fp->f_flag, fp->f_cred, td);
+ error = vn_close1(vp, fp->f_flag, fp->f_cred, td, ref);
- if (__predict_false((fp->f_flag & FHASLOCK) != 0) &&
- fp->f_type == DTYPE_VNODE) {
+ if (__predict_false(ref)) {
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
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