This patch removes the per-namespace semaphore in favor of a global
semaphore. This can have an effect on namespace scalability.
Signed-off-by: Miklos Szeredi <[email protected]>
fs/namespace.c | 44 ++++++++++++++++++++++----------------------
include/linux/namespace.h | 1 -
2 files changed, 22 insertions(+), 23 deletions(-)
Index: 2.6.13.sharedsubtree/include/linux/namespace.h
===================================================================
--- 2.6.13.sharedsubtree.orig/include/linux/namespace.h
+++ 2.6.13.sharedsubtree/include/linux/namespace.h
@@ -7,11 +7,10 @@
struct namespace {
atomic_t count;
struct vfsmount * root;
struct list_head list;
- struct rw_semaphore sem;
};
extern int copy_namespace(int, struct task_struct *);
extern void __put_namespace(struct namespace *namespace);
Index: 2.6.13.sharedsubtree/fs/namespace.c
===================================================================
--- 2.6.13.sharedsubtree.orig/fs/namespace.c
+++ 2.6.13.sharedsubtree/fs/namespace.c
@@ -41,10 +41,11 @@ static inline int sysfs_init(void)
__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
static struct list_head *mount_hashtable;
static int hash_mask, hash_bits;
static kmem_cache_t *mnt_cache;
+static struct rw_semaphore namespace_sem;
static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
{
unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
@@ -190,11 +191,11 @@ static void *m_start(struct seq_file *m,
{
struct namespace *n = m->private;
struct list_head *p;
loff_t l = *pos;
- down_read(&n->sem);
+ down_read(&namespace_sem);
list_for_each(p, &n->list)
if (!l--)
return list_entry(p, struct vfsmount, mnt_list);
return NULL;
}
@@ -207,12 +208,11 @@ static void *m_next(struct seq_file *m,
return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list);
}
static void m_stop(struct seq_file *m, void *v)
{
- struct namespace *n = m->private;
- up_read(&n->sem);
+ up_read(&namespace_sem);
}
static inline void mangle(struct seq_file *m, const char *s)
{
seq_escape(m, s, " \t\n\\");
@@ -434,11 +434,11 @@ static int do_umount(struct vfsmount *mn
}
up_write(&sb->s_umount);
return retval;
}
- down_write(¤t->namespace->sem);
+ down_write(&namespace_sem);
spin_lock(&vfsmount_lock);
if (atomic_read(&sb->s_active) == 1) {
/* last instance - try to be smart */
spin_unlock(&vfsmount_lock);
@@ -456,11 +456,11 @@ static int do_umount(struct vfsmount *mn
retval = 0;
}
spin_unlock(&vfsmount_lock);
if (retval)
security_sb_umount_busy(mnt);
- up_write(¤t->namespace->sem);
+ up_write(&namespace_sem);
return retval;
}
/*
* Now umount can handle mount points as well as block devices.
@@ -681,11 +681,11 @@ static int do_loopback(struct nameidata
return -EINVAL;
err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
if (err)
return err;
- down_write(¤t->namespace->sem);
+ down_write(&namespace_sem);
err = -EINVAL;
if (check_mnt(nd->mnt) && (!recurse || check_mnt(old_nd.mnt))) {
err = -ENOMEM;
if (recurse)
mnt = copy_tree(old_nd.mnt, old_nd.dentry);
@@ -706,11 +706,11 @@ static int do_loopback(struct nameidata
spin_unlock(&vfsmount_lock);
} else
mntput(mnt);
}
- up_write(¤t->namespace->sem);
+ up_write(&namespace_sem);
path_release(&old_nd);
return err;
}
/*
@@ -754,11 +754,11 @@ static int do_move_mount(struct nameidat
return -EINVAL;
err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
if (err)
return err;
- down_write(¤t->namespace->sem);
+ down_write(&namespace_sem);
while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) ;
err = -EINVAL;
if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
goto out;
@@ -797,11 +797,11 @@ static int do_move_mount(struct nameidat
out2:
spin_unlock(&vfsmount_lock);
out1:
up(&nd->dentry->d_inode->i_sem);
out:
- up_write(¤t->namespace->sem);
+ up_write(&namespace_sem);
if (!err)
path_release(&parent_nd);
path_release(&old_nd);
return err;
}
@@ -836,11 +836,11 @@ static int do_new_mount(struct nameidata
int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
int mnt_flags, struct list_head *fslist)
{
int err;
- down_write(¤t->namespace->sem);
+ down_write(&namespace_sem);
/* Something was mounted here while we slept */
while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) ;
err = -EINVAL;
if (!check_mnt(nd->mnt))
goto unlock;
@@ -865,11 +865,11 @@ int do_add_mount(struct vfsmount *newmnt
list_add_tail(&newmnt->mnt_expire, fslist);
spin_unlock(&vfsmount_lock);
}
unlock:
- up_write(¤t->namespace->sem);
+ up_write(&namespace_sem);
mntput(newmnt);
return err;
}
EXPORT_SYMBOL_GPL(do_add_mount);
@@ -969,13 +969,13 @@ void mark_mounts_for_expiry(struct list_
if (!namespace || !namespace->root)
continue;
get_namespace(namespace);
spin_unlock(&vfsmount_lock);
- down_write(&namespace->sem);
+ down_write(&namespace_sem);
expire_mount(mnt, mounts);
- up_write(&namespace->sem);
+ up_write(&namespace_sem);
mntput(mnt);
put_namespace(namespace);
spin_lock(&vfsmount_lock);
@@ -1141,18 +1141,17 @@ int copy_namespace(int flags, struct tas
new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL);
if (!new_ns)
goto out;
atomic_set(&new_ns->count, 1);
- init_rwsem(&new_ns->sem);
INIT_LIST_HEAD(&new_ns->list);
- down_write(&tsk->namespace->sem);
+ down_write(&namespace_sem);
/* First pass: copy the tree topology */
new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root);
if (!new_ns->root) {
- up_write(&tsk->namespace->sem);
+ up_write(&namespace_sem);
kfree(new_ns);
goto out;
}
spin_lock(&vfsmount_lock);
list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
@@ -1182,11 +1181,11 @@ int copy_namespace(int flags, struct tas
}
}
p = next_mnt(p, namespace->root);
q = next_mnt(q, new_ns->root);
}
- up_write(&tsk->namespace->sem);
+ up_write(&namespace_sem);
tsk->namespace = new_ns;
if (rootmnt)
mntput(rootmnt);
@@ -1368,11 +1367,11 @@ asmlinkage long sys_pivot_root(const cha
read_lock(¤t->fs->lock);
user_nd.mnt = mntget(current->fs->rootmnt);
user_nd.dentry = dget(current->fs->root);
read_unlock(¤t->fs->lock);
- down_write(¤t->namespace->sem);
+ down_write(&namespace_sem);
down(&old_nd.dentry->d_inode->i_sem);
error = -EINVAL;
if (!check_mnt(user_nd.mnt))
goto out2;
error = -ENOENT;
@@ -1414,11 +1413,11 @@ asmlinkage long sys_pivot_root(const cha
error = 0;
path_release(&root_parent);
path_release(&parent_nd);
out2:
up(&old_nd.dentry->d_inode->i_sem);
- up_write(¤t->namespace->sem);
+ up_write(&namespace_sem);
path_release(&user_nd);
path_release(&old_nd);
out1:
path_release(&new_nd);
out0:
@@ -1441,11 +1440,10 @@ static void __init init_mount_tree(void)
namespace = kmalloc(sizeof(*namespace), GFP_KERNEL);
if (!namespace)
panic("Can't allocate initial namespace");
atomic_set(&namespace->count, 1);
INIT_LIST_HEAD(&namespace->list);
- init_rwsem(&namespace->sem);
list_add(&mnt->mnt_list, &namespace->list);
namespace->root = mnt;
mnt->mnt_namespace = namespace;
init_task.namespace = namespace;
@@ -1465,10 +1463,12 @@ void __init mnt_init(unsigned long mempa
{
struct list_head *d;
unsigned int nr_hash;
int i;
+ init_rwsem(&namespace_sem);
+
mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL,
NULL);
mount_hashtable = (struct list_head *)
@@ -1514,12 +1514,12 @@ void __init mnt_init(unsigned long mempa
void __put_namespace(struct namespace *namespace)
{
struct vfsmount *root = namespace->root;
namespace->root = NULL;
spin_unlock(&vfsmount_lock);
- down_write(&namespace->sem);
+ down_write(&namespace_sem);
spin_lock(&vfsmount_lock);
umount_tree(root);
spin_unlock(&vfsmount_lock);
- up_write(&namespace->sem);
+ up_write(&namespace_sem);
kfree(namespace);
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
| |
 |