Author: jh
Date: Mon Sep 27 17:47:09 2010
New Revision: 213215
URL: http://svn.freebsd.org/changeset/base/213215
Log:
Add reference counting for devfs paths containing user created symbolic
links. The reference counting is needed to be able to determine if a
specific devfs path exists. For true device file paths we can traverse
the cdevp_list but a separate directory list is needed for user created
symbolic links.
Add a new directory entry flag DE_USER to mark entries which should
unreference their parent directory on deletion.
A new function to traverse cdevp_list and the directory list will be
introduced in a separate commit.
Idea from: kib
Reviewed by: kib
Added:
head/sys/fs/devfs/devfs_dir.c (contents, props changed)
Modified:
head/sys/conf/files
head/sys/fs/devfs/devfs.h
head/sys/fs/devfs/devfs_devs.c
head/sys/fs/devfs/devfs_int.h
head/sys/fs/devfs/devfs_vnops.c
Modified: head/sys/conf/files
==============================================================================
--- head/sys/conf/files Mon Sep 27 17:46:11 2010 (r213214)
+++ head/sys/conf/files Mon Sep 27 17:47:09 2010 (r213215)
@@ -1890,6 +1890,7 @@ fs/coda/coda_vfsops.c optional vcoda
fs/coda/coda_vnops.c optional vcoda
fs/deadfs/dead_vnops.c standard
fs/devfs/devfs_devs.c standard
+fs/devfs/devfs_dir.c standard
fs/devfs/devfs_rule.c standard
fs/devfs/devfs_vfsops.c standard
fs/devfs/devfs_vnops.c standard
Modified: head/sys/fs/devfs/devfs.h
==============================================================================
--- head/sys/fs/devfs/devfs.h Mon Sep 27 17:46:11 2010 (r213214)
+++ head/sys/fs/devfs/devfs.h Mon Sep 27 17:47:09 2010 (r213215)
@@ -124,6 +124,8 @@ MALLOC_DECLARE(M_DEVFS);
struct componentname;
+TAILQ_HEAD(devfs_dlist_head, devfs_dirent);
+
struct devfs_dirent {
struct cdev_priv *de_cdp;
int de_inode;
@@ -133,10 +135,11 @@ struct devfs_dirent {
#define DE_DOTDOT 0x04
#define DE_DOOMED 0x08
#define DE_COVERED 0x10
+#define DE_USER 0x20
int de_holdcnt;
struct dirent *de_dirent;
TAILQ_ENTRY(devfs_dirent) de_list;
- TAILQ_HEAD(, devfs_dirent) de_dlist;
+ struct devfs_dlist_head de_dlist;
struct devfs_dirent *de_dir;
int de_links;
mode_t de_mode;
Modified: head/sys/fs/devfs/devfs_devs.c
==============================================================================
--- head/sys/fs/devfs/devfs_devs.c Mon Sep 27 17:46:11 2010
(r213214)
+++ head/sys/fs/devfs/devfs_devs.c Mon Sep 27 17:47:09 2010
(r213215)
@@ -338,6 +338,10 @@ devfs_delete(struct devfs_mount *dm, str
dd = devfs_parent_dirent(de);
if (dd != NULL)
DEVFS_DE_HOLD(dd);
+ if (de->de_flags & DE_USER) {
+ KASSERT(dd != NULL, ("devfs_delete: NULL dd"));
+ devfs_dir_unref_de(dm, dd);
+ }
} else
dd = NULL;
@@ -396,10 +400,17 @@ devfs_purge(struct devfs_mount *dm, stru
DEVFS_DE_HOLD(dd);
for (;;) {
- de = TAILQ_FIRST(&dd->de_dlist);
+ /*
+ * Use TAILQ_LAST() to remove "." and ".." last.
+ * We might need ".." to resolve a path in
+ * devfs_dir_unref_de().
+ */
+ de = TAILQ_LAST(&dd->de_dlist, devfs_dlist_head);
if (de == NULL)
break;
TAILQ_REMOVE(&dd->de_dlist, de, de_list);
+ if (de->de_flags & DE_USER)
+ devfs_dir_unref_de(dm, dd);
if (de->de_flags & (DE_DOT | DE_DOTDOT))
devfs_delete(dm, de, DEVFS_DEL_NORECURSE);
else if (de->de_dirent->d_type == DT_DIR)
Added: head/sys/fs/devfs/devfs_dir.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/fs/devfs/devfs_dir.c Mon Sep 27 17:47:09 2010
(r213215)
@@ -0,0 +1,175 @@
+/*-
+ * Copyright (c) 2010 Jaakko Heinonen <j...@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/conf.h>
+#include <sys/types.h>
+#include <sys/kernel.h>
+#include <sys/libkern.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/queue.h>
+#include <sys/systm.h>
+#include <sys/sx.h>
+
+#include <fs/devfs/devfs.h>
+#include <fs/devfs/devfs_int.h>
+
+struct dirlistent {
+ char *dir;
+ int refcnt;
+ LIST_ENTRY(dirlistent) link;
+};
+
+static LIST_HEAD(, dirlistent) devfs_dirlist =
+ LIST_HEAD_INITIALIZER(devfs_dirlist);
+
+static MALLOC_DEFINE(M_DEVFS4, "DEVFS4", "DEVFS directory list");
+
+static struct mtx dirlist_mtx;
+MTX_SYSINIT(dirlist_mtx, &dirlist_mtx, "devfs dirlist lock", MTX_DEF);
+
+/* Returns 1 if the path is in the directory list. */
+int
+devfs_dir_find(const char *path)
+{
+ struct dirlistent *dle;
+
+ mtx_lock(&dirlist_mtx);
+ LIST_FOREACH(dle, &devfs_dirlist, link) {
+ if (devfs_pathpath(dle->dir, path) != 0) {
+ mtx_unlock(&dirlist_mtx);
+ return (1);
+ }
+ }
+ mtx_unlock(&dirlist_mtx);
+
+ return (0);
+}
+
+static struct dirlistent *
+devfs_dir_findent_locked(const char *dir)
+{
+ struct dirlistent *dle;
+
+ mtx_assert(&dirlist_mtx, MA_OWNED);
+
+ LIST_FOREACH(dle, &devfs_dirlist, link) {
+ if (strcmp(dir, dle->dir) == 0)
+ return (dle);
+ }
+
+ return (NULL);
+}
+
+static void
+devfs_dir_ref(const char *dir)
+{
+ struct dirlistent *dle, *dle_new;
+
+ if (*dir == '\0')
+ return;
+
+ dle_new = malloc(sizeof(*dle), M_DEVFS4, M_WAITOK);
+ dle_new->dir = strdup(dir, M_DEVFS4);
+ dle_new->refcnt = 1;
+
+ mtx_lock(&dirlist_mtx);
+ dle = devfs_dir_findent_locked(dir);
+ if (dle != NULL) {
+ dle->refcnt++;
+ mtx_unlock(&dirlist_mtx);
+ free(dle_new->dir, M_DEVFS4);
+ free(dle_new, M_DEVFS4);
+ return;
+ }
+ LIST_INSERT_HEAD(&devfs_dirlist, dle_new, link);
+ mtx_unlock(&dirlist_mtx);
+}
+
+void
+devfs_dir_ref_de(struct devfs_mount *dm, struct devfs_dirent *de)
+{
+ char dirname[SPECNAMELEN + 1], *namep;
+
+ namep = devfs_fqpn(dirname, dm, de, NULL);
+ KASSERT(namep != NULL, ("devfs_ref_dir_de: NULL namep"));
+
+ devfs_dir_ref(namep);
+}
+
+static void
+devfs_dir_unref(const char *dir)
+{
+ struct dirlistent *dle;
+
+ if (*dir == '\0')
+ return;
+
+ mtx_lock(&dirlist_mtx);
+ dle = devfs_dir_findent_locked(dir);
+ KASSERT(dle != NULL, ("devfs_dir_unref: dir %s not referenced", dir));
+ dle->refcnt--;
+ KASSERT(dle->refcnt >= 0, ("devfs_dir_unref: negative refcnt"));
+ if (dle->refcnt == 0) {
+ LIST_REMOVE(dle, link);
+ mtx_unlock(&dirlist_mtx);
+ free(dle->dir, M_DEVFS4);
+ free(dle, M_DEVFS4);
+ } else
+ mtx_unlock(&dirlist_mtx);
+}
+
+void
+devfs_dir_unref_de(struct devfs_mount *dm, struct devfs_dirent *de)
+{
+ char dirname[SPECNAMELEN + 1], *namep;
+
+ namep = devfs_fqpn(dirname, dm, de, NULL);
+ KASSERT(namep != NULL, ("devfs_unref_dir_de: NULL namep"));
+
+ devfs_dir_unref(namep);
+}
+
+/* Returns 1 if the path p1 contains the path p2. */
+int
+devfs_pathpath(const char *p1, const char *p2)
+{
+
+ for (;;p1++, p2++) {
+ if (*p1 != *p2) {
+ if (*p1 == '/' && *p2 == '\0')
+ return (1);
+ else
+ return (0);
+ } else if (*p1 == '\0')
+ return (1);
+ }
+ /* NOTREACHED */
+}
Modified: head/sys/fs/devfs/devfs_int.h
==============================================================================
--- head/sys/fs/devfs/devfs_int.h Mon Sep 27 17:46:11 2010
(r213214)
+++ head/sys/fs/devfs/devfs_int.h Mon Sep 27 17:47:09 2010
(r213215)
@@ -38,6 +38,7 @@
#ifdef _KERNEL
struct devfs_dirent;
+struct devfs_mount;
struct cdev_privdata {
struct file *cdpd_fp;
@@ -76,6 +77,11 @@ void devfs_create(struct cdev *dev);
void devfs_destroy(struct cdev *dev);
void devfs_destroy_cdevpriv(struct cdev_privdata *p);
+int devfs_dir_find(const char *);
+void devfs_dir_ref_de(struct devfs_mount *, struct devfs_dirent *);
+void devfs_dir_unref_de(struct devfs_mount *, struct devfs_dirent *);
+int devfs_pathpath(const char *, const char *);
+
extern struct unrhdr *devfs_inos;
extern struct mtx devmtx;
extern struct mtx devfs_de_interlock;
Modified: head/sys/fs/devfs/devfs_vnops.c
==============================================================================
--- head/sys/fs/devfs/devfs_vnops.c Mon Sep 27 17:46:11 2010
(r213214)
+++ head/sys/fs/devfs/devfs_vnops.c Mon Sep 27 17:47:09 2010
(r213215)
@@ -1564,6 +1564,7 @@ devfs_symlink(struct vop_symlink_args *a
dd = ap->a_dvp->v_data;
de = devfs_newdirent(ap->a_cnp->cn_nameptr, ap->a_cnp->cn_namelen);
+ de->de_flags = DE_USER;
de->de_uid = 0;
de->de_gid = 0;
de->de_mode = 0755;
@@ -1587,6 +1588,7 @@ devfs_symlink(struct vop_symlink_args *a
de_dotdot = TAILQ_FIRST(&dd->de_dlist); /* "." */
de_dotdot = TAILQ_NEXT(de_dotdot, de_list); /* ".." */
TAILQ_INSERT_AFTER(&dd->de_dlist, de_dotdot, de, de_list);
+ devfs_dir_ref_de(dmp, dd);
return (devfs_allocv(de, ap->a_dvp->v_mount, LK_EXCLUSIVE, ap->a_vpp));
}
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