Module Name: src
Committed By: hannken
Date: Fri Feb 17 08:24:07 UTC 2017
Modified Files:
src/sys/kern: vfs_trans.c
Log Message:
Protect attaching and detaching lwp_info to mount with a mutex.
To generate a diff of this commit:
cvs rdiff -u -r1.34 -r1.35 src/sys/kern/vfs_trans.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_trans.c
diff -u src/sys/kern/vfs_trans.c:1.34 src/sys/kern/vfs_trans.c:1.35
--- src/sys/kern/vfs_trans.c:1.34 Mon Aug 24 22:50:32 2015
+++ src/sys/kern/vfs_trans.c Fri Feb 17 08:24:07 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_trans.c,v 1.34 2015/08/24 22:50:32 pooka Exp $ */
+/* $NetBSD: vfs_trans.c,v 1.35 2017/02/17 08:24:07 hannken Exp $ */
/*-
* Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.34 2015/08/24 22:50:32 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.35 2017/02/17 08:24:07 hannken Exp $");
/*
* File system transaction operations.
@@ -78,6 +78,7 @@ struct fstrans_mount_info {
static specificdata_key_t lwp_data_key; /* Our specific data key. */
static kmutex_t vfs_suspend_lock; /* Serialize suspensions. */
static kmutex_t fstrans_lock; /* Fstrans big lock. */
+static kmutex_t fstrans_mount_lock; /* Fstrans mount big lock. */
static kcondvar_t fstrans_state_cv; /* Fstrans or cow state changed. */
static kcondvar_t fstrans_count_cv; /* Fstrans or cow count changed. */
static pserialize_t fstrans_psz; /* Pserialize state. */
@@ -106,6 +107,7 @@ fstrans_init(void)
mutex_init(&vfs_suspend_lock, MUTEX_DEFAULT, IPL_NONE);
mutex_init(&fstrans_lock, MUTEX_DEFAULT, IPL_NONE);
+ mutex_init(&fstrans_mount_lock, MUTEX_DEFAULT, IPL_NONE);
cv_init(&fstrans_state_cv, "fstchg");
cv_init(&fstrans_count_cv, "fstcnt");
fstrans_psz = pserialize_create();
@@ -140,17 +142,25 @@ fstrans_mount_dtor(struct mount *mp)
{
struct fstrans_mount_info *fmi;
+ mutex_enter(&fstrans_mount_lock);
+
fmi = mp->mnt_transinfo;
- if (atomic_dec_uint_nv(&fmi->fmi_ref_cnt) > 0)
+ KASSERT(fmi != NULL);
+ fmi->fmi_ref_cnt -= 1;
+ if (fmi->fmi_ref_cnt > 0) {
+ mutex_exit(&fstrans_mount_lock);
return;
+ }
KASSERT(fmi->fmi_state == FSTRANS_NORMAL);
KASSERT(LIST_FIRST(&fmi->fmi_cow_handler) == NULL);
- kmem_free(fmi, sizeof(*fmi));
mp->mnt_iflag &= ~IMNT_HAS_TRANS;
mp->mnt_transinfo = NULL;
+ mutex_exit(&fstrans_mount_lock);
+
+ kmem_free(fmi, sizeof(*fmi));
vfs_destroy(mp);
}
@@ -172,8 +182,10 @@ fstrans_mount(struct mount *mp)
LIST_INIT(&newfmi->fmi_cow_handler);
newfmi->fmi_cow_change = false;
+ mutex_enter(&fstrans_mount_lock);
mp->mnt_transinfo = newfmi;
mp->mnt_iflag |= IMNT_HAS_TRANS;
+ mutex_exit(&fstrans_mount_lock);
vfs_unbusy(mp, true, NULL);
@@ -236,6 +248,7 @@ fstrans_get_lwp_info(struct mount *mp, b
mutex_enter(&fstrans_lock);
LIST_FOREACH(fli, &fstrans_fli_head, fli_list) {
if (fli->fli_self == NULL) {
+ KASSERT(fli->fli_mount == NULL);
KASSERT(fli->fli_trans_cnt == 0);
KASSERT(fli->fli_cow_cnt == 0);
fli->fli_self = curlwp;
@@ -260,9 +273,16 @@ fstrans_get_lwp_info(struct mount *mp, b
/*
* Attach the entry to the mount.
*/
- fmi = mp->mnt_transinfo;
- fli->fli_mount = mp;
- atomic_inc_uint(&fmi->fmi_ref_cnt);
+ mutex_enter(&fstrans_mount_lock);
+ if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) {
+ fli = NULL;
+ } else {
+ fmi = mp->mnt_transinfo;
+ KASSERT(fmi != NULL);
+ fli->fli_mount = mp;
+ fmi->fmi_ref_cnt += 1;
+ }
+ mutex_exit(&fstrans_mount_lock);
return fli;
}
@@ -297,11 +317,9 @@ _fstrans_start(struct mount *mp, enum fs
ASSERT_SLEEPABLE();
- if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0)
+ if (mp == NULL || (fli = fstrans_get_lwp_info(mp, true)) == NULL)
return 0;
- fli = fstrans_get_lwp_info(mp, true);
-
if (fli->fli_trans_cnt > 0) {
KASSERT(lock_type != FSTRANS_EXCL);
fli->fli_trans_cnt += 1;
@@ -343,11 +361,9 @@ fstrans_done(struct mount *mp)
struct fstrans_lwp_info *fli;
struct fstrans_mount_info *fmi;
- if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0)
+ if (mp == NULL || (fli = fstrans_get_lwp_info(mp, true)) == NULL)
return;
- fli = fstrans_get_lwp_info(mp, false);
- KASSERT(fli != NULL);
KASSERT(fli->fli_trans_cnt > 0);
if (fli->fli_trans_cnt > 1) {
@@ -380,11 +396,10 @@ fstrans_is_owner(struct mount *mp)
{
struct fstrans_lwp_info *fli;
- if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0)
+ if (mp == NULL || (fli = fstrans_get_lwp_info(mp, false)) == NULL)
return 0;
- fli = fstrans_get_lwp_info(mp, false);
- if (fli == NULL || fli->fli_trans_cnt == 0)
+ if (fli->fli_trans_cnt == 0)
return 0;
KASSERT(fli->fli_mount == mp);
