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Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c94
1 files changed, 70 insertions, 24 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 2dd333b0fe7f..7230787d18b0 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -22,6 +22,7 @@
#include <linux/seq_file.h>
#include <linux/mnt_namespace.h>
#include <linux/namei.h>
+#include <linux/nsproxy.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/ramfs.h>
@@ -42,6 +43,8 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
static int event;
static DEFINE_IDA(mnt_id_ida);
static DEFINE_IDA(mnt_group_ida);
+static int mnt_id_start = 0;
+static int mnt_group_start = 1;
static struct list_head *mount_hashtable __read_mostly;
static struct kmem_cache *mnt_cache __read_mostly;
@@ -69,7 +72,9 @@ static int mnt_alloc_id(struct vfsmount *mnt)
retry:
ida_pre_get(&mnt_id_ida, GFP_KERNEL);
spin_lock(&vfsmount_lock);
- res = ida_get_new(&mnt_id_ida, &mnt->mnt_id);
+ res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id);
+ if (!res)
+ mnt_id_start = mnt->mnt_id + 1;
spin_unlock(&vfsmount_lock);
if (res == -EAGAIN)
goto retry;
@@ -79,8 +84,11 @@ retry:
static void mnt_free_id(struct vfsmount *mnt)
{
+ int id = mnt->mnt_id;
spin_lock(&vfsmount_lock);
- ida_remove(&mnt_id_ida, mnt->mnt_id);
+ ida_remove(&mnt_id_ida, id);
+ if (mnt_id_start > id)
+ mnt_id_start = id;
spin_unlock(&vfsmount_lock);
}
@@ -91,10 +99,18 @@ static void mnt_free_id(struct vfsmount *mnt)
*/
static int mnt_alloc_group_id(struct vfsmount *mnt)
{
+ int res;
+
if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL))
return -ENOMEM;
- return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id);
+ res = ida_get_new_above(&mnt_group_ida,
+ mnt_group_start,
+ &mnt->mnt_group_id);
+ if (!res)
+ mnt_group_start = mnt->mnt_group_id + 1;
+
+ return res;
}
/*
@@ -102,7 +118,10 @@ static int mnt_alloc_group_id(struct vfsmount *mnt)
*/
void mnt_release_group_id(struct vfsmount *mnt)
{
- ida_remove(&mnt_group_ida, mnt->mnt_group_id);
+ int id = mnt->mnt_group_id;
+ ida_remove(&mnt_group_ida, id);
+ if (mnt_group_start > id)
+ mnt_group_start = id;
mnt->mnt_group_id = 0;
}
@@ -297,7 +316,8 @@ EXPORT_SYMBOL_GPL(mnt_clone_write);
*/
int mnt_want_write_file(struct file *file)
{
- if (!(file->f_mode & FMODE_WRITE))
+ struct inode *inode = file->f_dentry->d_inode;
+ if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode))
return mnt_want_write(file->f_path.mnt);
else
return mnt_clone_write(file->f_path.mnt);
@@ -1937,6 +1957,21 @@ dput_out:
return retval;
}
+static struct mnt_namespace *alloc_mnt_ns(void)
+{
+ struct mnt_namespace *new_ns;
+
+ new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
+ if (!new_ns)
+ return ERR_PTR(-ENOMEM);
+ atomic_set(&new_ns->count, 1);
+ new_ns->root = NULL;
+ INIT_LIST_HEAD(&new_ns->list);
+ init_waitqueue_head(&new_ns->poll);
+ new_ns->event = 0;
+ return new_ns;
+}
+
/*
* Allocate a new namespace structure and populate it with contents
* copied from the namespace of the passed in task structure.
@@ -1948,14 +1983,9 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
struct vfsmount *p, *q;
- new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
- if (!new_ns)
- return ERR_PTR(-ENOMEM);
-
- atomic_set(&new_ns->count, 1);
- INIT_LIST_HEAD(&new_ns->list);
- init_waitqueue_head(&new_ns->poll);
- new_ns->event = 0;
+ new_ns = alloc_mnt_ns();
+ if (IS_ERR(new_ns))
+ return new_ns;
down_write(&namespace_sem);
/* First pass: copy the tree topology */
@@ -2019,6 +2049,24 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
return new_ns;
}
+/**
+ * create_mnt_ns - creates a private namespace and adds a root filesystem
+ * @mnt: pointer to the new root filesystem mountpoint
+ */
+struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt)
+{
+ struct mnt_namespace *new_ns;
+
+ new_ns = alloc_mnt_ns();
+ if (!IS_ERR(new_ns)) {
+ mnt->mnt_ns = new_ns;
+ new_ns->root = mnt;
+ list_add(&new_ns->list, &new_ns->root->mnt_list);
+ }
+ return new_ns;
+}
+EXPORT_SYMBOL(create_mnt_ns);
+
SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
char __user *, type, unsigned long, flags, void __user *, data)
{
@@ -2194,16 +2242,9 @@ static void __init init_mount_tree(void)
mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
if (IS_ERR(mnt))
panic("Can't create rootfs");
- ns = kmalloc(sizeof(*ns), GFP_KERNEL);
- if (!ns)
+ ns = create_mnt_ns(mnt);
+ if (IS_ERR(ns))
panic("Can't allocate initial namespace");
- atomic_set(&ns->count, 1);
- INIT_LIST_HEAD(&ns->list);
- init_waitqueue_head(&ns->poll);
- ns->event = 0;
- list_add(&mnt->mnt_list, &ns->list);
- ns->root = mnt;
- mnt->mnt_ns = ns;
init_task.nsproxy->mnt_ns = ns;
get_mnt_ns(ns);
@@ -2246,10 +2287,14 @@ void __init mnt_init(void)
init_mount_tree();
}
-void __put_mnt_ns(struct mnt_namespace *ns)
+void put_mnt_ns(struct mnt_namespace *ns)
{
- struct vfsmount *root = ns->root;
+ struct vfsmount *root;
LIST_HEAD(umount_list);
+
+ if (!atomic_dec_and_lock(&ns->count, &vfsmount_lock))
+ return;
+ root = ns->root;
ns->root = NULL;
spin_unlock(&vfsmount_lock);
down_write(&namespace_sem);
@@ -2260,3 +2305,4 @@ void __put_mnt_ns(struct mnt_namespace *ns)
release_mounts(&umount_list);
kfree(ns);
}
+EXPORT_SYMBOL(put_mnt_ns);