Module Name: src
Committed By: chs
Date: Tue Dec 29 22:13:40 UTC 2020
Modified Files:
src/sys/kern: vfs_lookup.c
Log Message:
Honor LOCKPARENT for ".." of the root directory.
Reported-by: [email protected]
To generate a diff of this commit:
cvs rdiff -u -r1.224 -r1.225 src/sys/kern/vfs_lookup.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/vfs_lookup.c
diff -u src/sys/kern/vfs_lookup.c:1.224 src/sys/kern/vfs_lookup.c:1.225
--- src/sys/kern/vfs_lookup.c:1.224 Mon Jun 15 18:44:10 2020
+++ src/sys/kern/vfs_lookup.c Tue Dec 29 22:13:40 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_lookup.c,v 1.224 2020/06/15 18:44:10 ad Exp $ */
+/* $NetBSD: vfs_lookup.c,v 1.225 2020/12/29 22:13:40 chs Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.224 2020/06/15 18:44:10 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.225 2020/12/29 22:13:40 chs Exp $");
#ifdef _KERNEL_OPT
#include "opt_magiclinks.h"
@@ -1047,6 +1047,28 @@ lookup_crossmount(struct namei_state *st
}
/*
+ * Determine the desired locking mode for the directory of a lookup.
+ */
+static int
+lookup_lktype(struct vnode *searchdir, struct componentname *cnp)
+{
+
+ /*
+ * If the file system supports VOP_LOOKUP() with a shared lock, and
+ * we are not making any modifications (nameiop LOOKUP) or this is
+ * not the last component then get a shared lock. Where we can't do
+ * fast-forwarded lookups (for example with layered file systems)
+ * then this is the fallback for reducing lock contention.
+ */
+ if ((searchdir->v_mount->mnt_iflag & IMNT_SHRLOOKUP) != 0 &&
+ (cnp->cn_nameiop == LOOKUP || (cnp->cn_flags & ISLASTCN) == 0)) {
+ return LK_SHARED;
+ } else {
+ return LK_EXCLUSIVE;
+ }
+}
+
+/*
* Call VOP_LOOKUP for a single lookup; return a new search directory
* (used when crossing mountpoints up or searching union mounts down) and
* the found object, which for create operations may be NULL on success.
@@ -1100,6 +1122,11 @@ lookup_once(struct namei_state *state,
foundobj = searchdir;
vref(foundobj);
*foundobj_ret = foundobj;
+ if (cnp->cn_flags & LOCKPARENT) {
+ lktype = lookup_lktype(searchdir, cnp);
+ vn_lock(searchdir, lktype | LK_RETRY);
+ searchdir_locked = true;
+ }
error = 0;
goto done;
}
@@ -1137,19 +1164,7 @@ lookup_once(struct namei_state *state,
}
}
- /*
- * If the file system supports VOP_LOOKUP() with a shared lock, and
- * we are not making any modifications (nameiop LOOKUP) or this is
- * not the last component then get a shared lock. Where we can't do
- * fast-forwarded lookups (for example with layered file systems)
- * then this is the fallback for reducing lock contention.
- */
- if ((searchdir->v_mount->mnt_iflag & IMNT_SHRLOOKUP) != 0 &&
- (cnp->cn_nameiop == LOOKUP || (cnp->cn_flags & ISLASTCN) == 0)) {
- lktype = LK_SHARED;
- } else {
- lktype = LK_EXCLUSIVE;
- }
+ lktype = lookup_lktype(searchdir, cnp);
/*
* We now have a segment name to search for, and a directory to search.
