Module Name: src
Committed By: hannken
Date: Mon Jun 17 08:07:27 UTC 2019
Modified Files:
src/sys/kern: vfs_trans.c
Log Message:
Add an owner field to fstrans mount info and use it to hold
the thread currently suspending this mount.
Remove now unneeded state FSTRANS_EXCL.
It is now possible to suspend a file system from a thread
already holding fstrans locks. Use with care ...
To generate a diff of this commit:
cvs rdiff -u -r1.60 -r1.61 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:1.60 src/sys/kern/vfs_trans.c:1.61
--- src/sys/kern/vfs_trans.c:1.60 Mon May 13 08:16:56 2019
+++ src/sys/kern/vfs_trans.c Mon Jun 17 08:07:27 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_trans.c,v 1.60 2019/05/13 08:16:56 hannken Exp $ */
+/* $NetBSD: vfs_trans.c,v 1.61 2019/06/17 08:07:27 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 1.60 2019/05/13 08:16:56 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.61 2019/06/17 08:07:27 hannken Exp $");
/*
* File system transaction operations.
@@ -55,8 +55,7 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,
enum fstrans_lock_type {
FSTRANS_LAZY, /* Granted while not suspended */
- FSTRANS_SHARED, /* Granted while not suspending */
- FSTRANS_EXCL /* Internal: exclusive lock */
+ FSTRANS_SHARED /* Granted while not suspending */
};
struct fscow_handler {
@@ -83,6 +82,7 @@ struct fstrans_mount_info {
bool fmi_cow_change;
LIST_HEAD(, fscow_handler) fmi_cow_handler;
struct mount *fmi_mount;
+ struct lwp *fmi_owner;
};
static kmutex_t vfs_suspend_lock; /* Serialize suspensions. */
@@ -101,7 +101,8 @@ static inline struct fstrans_lwp_info *
fstrans_get_lwp_info(struct mount *, bool);
static struct fstrans_lwp_info *fstrans_alloc_lwp_info(struct mount *);
static inline int _fstrans_start(struct mount *, enum fstrans_lock_type, int);
-static bool grant_lock(const enum fstrans_state, const enum fstrans_lock_type);
+static bool grant_lock(const struct fstrans_mount_info *,
+ const enum fstrans_lock_type);
static bool state_change_done(const struct fstrans_mount_info *);
static bool cow_state_change_done(const struct fstrans_mount_info *);
static void cow_change_enter(struct fstrans_mount_info *);
@@ -233,6 +234,7 @@ fstrans_mount_dtor(struct fstrans_mount_
KASSERT(fmi->fmi_state == FSTRANS_NORMAL);
KASSERT(LIST_FIRST(&fmi->fmi_cow_handler) == NULL);
+ KASSERT(fmi->fmi_owner == NULL);
KASSERT(fstrans_gone_count > 0);
fstrans_gone_count -= 1;
@@ -258,6 +260,7 @@ fstrans_mount(struct mount *mp)
LIST_INIT(&newfmi->fmi_cow_handler);
newfmi->fmi_cow_change = false;
newfmi->fmi_mount = mp;
+ newfmi->fmi_owner = NULL;
mutex_enter(&fstrans_mount_lock);
mp->mnt_transinfo = newfmi;
@@ -433,14 +436,15 @@ fstrans_get_lwp_info(struct mount *mp, b
* Check if this lock type is granted at this state.
*/
static bool
-grant_lock(const enum fstrans_state state, const enum fstrans_lock_type type)
+grant_lock(const struct fstrans_mount_info *fmi,
+ const enum fstrans_lock_type type)
{
- if (__predict_true(state == FSTRANS_NORMAL))
+ if (__predict_true(fmi->fmi_state == FSTRANS_NORMAL))
return true;
- if (type == FSTRANS_EXCL)
+ if (fmi->fmi_owner == curlwp)
return true;
- if (state == FSTRANS_SUSPENDING && type == FSTRANS_LAZY)
+ if (fmi->fmi_state == FSTRANS_SUSPENDING && type == FSTRANS_LAZY)
return true;
return false;
@@ -468,14 +472,13 @@ _fstrans_start(struct mount *mp, enum fs
fmi = fli->fli_mountinfo;
if (fli->fli_trans_cnt > 0) {
- KASSERT(lock_type != FSTRANS_EXCL);
fli->fli_trans_cnt += 1;
return 0;
}
s = pserialize_read_enter();
- if (__predict_true(grant_lock(fmi->fmi_state, lock_type))) {
+ if (__predict_true(grant_lock(fmi, lock_type))) {
fli->fli_trans_cnt = 1;
fli->fli_lock_type = lock_type;
pserialize_read_exit(s);
@@ -488,7 +491,7 @@ _fstrans_start(struct mount *mp, enum fs
return EBUSY;
mutex_enter(&fstrans_lock);
- while (! grant_lock(fmi->fmi_state, lock_type))
+ while (! grant_lock(fmi, lock_type))
cv_wait(&fstrans_state_cv, &fstrans_lock);
fli->fli_trans_cnt = 1;
fli->fli_lock_type = lock_type;
@@ -572,15 +575,14 @@ int
fstrans_is_owner(struct mount *mp)
{
struct fstrans_lwp_info *fli;
+ struct fstrans_mount_info *fmi;
KASSERT(mp != dead_rootmount);
fli = fstrans_get_lwp_info(mp, true);
+ fmi = fli->fli_mountinfo;
- if (fli->fli_trans_cnt == 0)
- return 0;
-
- return (fli->fli_lock_type == FSTRANS_EXCL);
+ return (fmi->fmi_owner == curlwp);
}
/*
@@ -598,7 +600,9 @@ state_change_done(const struct fstrans_m
continue;
if (fli->fli_trans_cnt == 0)
continue;
- if (grant_lock(fmi->fmi_state, fli->fli_lock_type))
+ if (fli->fli_self == curlwp)
+ continue;
+ if (grant_lock(fmi, fli->fli_lock_type))
continue;
return false;
@@ -642,15 +646,18 @@ fstrans_setstate(struct mount *mp, enum
break;
}
}
- cv_broadcast(&fstrans_state_cv);
- mutex_exit(&fstrans_lock);
-
if (old_state != new_state) {
- if (old_state == FSTRANS_NORMAL)
- _fstrans_start(mp, FSTRANS_EXCL, 1);
- if (new_state == FSTRANS_NORMAL)
- fstrans_done(mp);
+ if (old_state == FSTRANS_NORMAL) {
+ KASSERT(fmi->fmi_owner == NULL);
+ fmi->fmi_owner = curlwp;
+ }
+ if (new_state == FSTRANS_NORMAL) {
+ KASSERT(fmi->fmi_owner == curlwp);
+ fmi->fmi_owner = NULL;
+ }
}
+ cv_broadcast(&fstrans_state_cv);
+ mutex_exit(&fstrans_lock);
return error;
}
@@ -976,9 +983,6 @@ fstrans_print_lwp(struct proc *p, struct
case FSTRANS_SHARED:
printf(" shared");
break;
- case FSTRANS_EXCL:
- printf(" excl");
- break;
default:
printf(" %#x", fli->fli_lock_type);
break;
@@ -1004,6 +1008,7 @@ fstrans_print_mount(struct mount *mp, in
printf("(null)\n");
return;
}
+ printf("owner %p ", fmi->fmi_owner);
switch (fmi->fmi_state) {
case FSTRANS_NORMAL:
printf("state normal\n");
