Author: mjg
Date: Fri Aug 7 19:36:08 2020
New Revision: 364042
URL: https://svnweb.freebsd.org/changeset/base/364042
Log:
vfs: release the interlock after failing to set VHOLD_NO_SMR
While here add more comments.
Diagnosed by: markj
Reported by: pho
Fixes: r362827 ("vfs: protect vnodes with smr")
Modified:
head/sys/kern/vfs_subr.c
Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c Fri Aug 7 19:33:54 2020 (r364041)
+++ head/sys/kern/vfs_subr.c Fri Aug 7 19:36:08 2020 (r364042)
@@ -3683,19 +3683,24 @@ vdropl(struct vnode *vp)
}
if (!VN_IS_DOOMED(vp)) {
vdrop_deactivate(vp);
+ /*
+ * Also unlocks the interlock. We can't assert on it as we
+ * released our hold and by now the vnode might have been
+ * freed.
+ */
return;
}
/*
- * We may be racing against vhold_smr.
+ * Set the VHOLD_NO_SMR flag.
*
- * If they win we can just pretend we never got this far, they will
- * vdrop later.
+ * We may be racing against vhold_smr. If they win we can just pretend
+ * we never got this far, they will vdrop later.
*/
if (!atomic_cmpset_int(&vp->v_holdcnt, 0, VHOLD_NO_SMR)) {
+ VI_UNLOCK(vp);
/*
- * We lost the aforementioned race. Note that any subsequent
- * access is invalid as they might have managed to vdropl on
- * their own.
+ * We lost the aforementioned race. Any subsequent access is
+ * invalid as they might have managed to vdropl on their own.
*/
return;
}
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