Take fs_struct handling to new file (fs/fs_struct.c)
Pure code move; two new helper functions for nfsd and daemonize
(unshare_fs_struct() and daemonize_fs_struct() resp.; for now -
the same code as used to be in callers). unshare_fs_struct()
exported (for nfsd, as copy_fs_struct()/exit_fs() used to be),
copy_fs_struct() and exit_fs() don't need exports anymore.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/fs_struct.c b/fs/fs_struct.c
new file mode 100644
index 0000000..36e0a12
--- /dev/null
+++ b/fs/fs_struct.c
@@ -0,0 +1,141 @@
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/path.h>
+#include <linux/slab.h>
+
+/*
+ * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
+ * It can block.
+ */
+void set_fs_root(struct fs_struct *fs, struct path *path)
+{
+ struct path old_root;
+
+ write_lock(&fs->lock);
+ old_root = fs->root;
+ fs->root = *path;
+ path_get(path);
+ write_unlock(&fs->lock);
+ if (old_root.dentry)
+ path_put(&old_root);
+}
+
+/*
+ * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
+ * It can block.
+ */
+void set_fs_pwd(struct fs_struct *fs, struct path *path)
+{
+ struct path old_pwd;
+
+ write_lock(&fs->lock);
+ old_pwd = fs->pwd;
+ fs->pwd = *path;
+ path_get(path);
+ write_unlock(&fs->lock);
+
+ if (old_pwd.dentry)
+ path_put(&old_pwd);
+}
+
+void chroot_fs_refs(struct path *old_root, struct path *new_root)
+{
+ struct task_struct *g, *p;
+ struct fs_struct *fs;
+ int count = 0;
+
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ task_lock(p);
+ fs = p->fs;
+ if (fs) {
+ write_lock(&fs->lock);
+ if (fs->root.dentry == old_root->dentry
+ && fs->root.mnt == old_root->mnt) {
+ path_get(new_root);
+ fs->root = *new_root;
+ count++;
+ }
+ if (fs->pwd.dentry == old_root->dentry
+ && fs->pwd.mnt == old_root->mnt) {
+ path_get(new_root);
+ fs->pwd = *new_root;
+ count++;
+ }
+ write_unlock(&fs->lock);
+ }
+ task_unlock(p);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+ while (count--)
+ path_put(old_root);
+}
+
+void put_fs_struct(struct fs_struct *fs)
+{
+ /* No need to hold fs->lock if we are killing it */
+ if (atomic_dec_and_test(&fs->count)) {
+ path_put(&fs->root);
+ path_put(&fs->pwd);
+ kmem_cache_free(fs_cachep, fs);
+ }
+}
+
+void exit_fs(struct task_struct *tsk)
+{
+ struct fs_struct * fs = tsk->fs;
+
+ if (fs) {
+ task_lock(tsk);
+ tsk->fs = NULL;
+ task_unlock(tsk);
+ put_fs_struct(fs);
+ }
+}
+
+struct fs_struct *copy_fs_struct(struct fs_struct *old)
+{
+ struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
+ /* We don't need to lock fs - think why ;-) */
+ if (fs) {
+ atomic_set(&fs->count, 1);
+ rwlock_init(&fs->lock);
+ fs->umask = old->umask;
+ read_lock(&old->lock);
+ fs->root = old->root;
+ path_get(&old->root);
+ fs->pwd = old->pwd;
+ path_get(&old->pwd);
+ read_unlock(&old->lock);
+ }
+ return fs;
+}
+
+int unshare_fs_struct(void)
+{
+ struct fs_struct *fsp = copy_fs_struct(current->fs);
+ if (!fsp)
+ return -ENOMEM;
+ exit_fs(current);
+ current->fs = fsp;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(unshare_fs_struct);
+
+/* to be mentioned only in INIT_TASK */
+struct fs_struct init_fs = {
+ .count = ATOMIC_INIT(1),
+ .lock = __RW_LOCK_UNLOCKED(init_fs.lock),
+ .umask = 0022,
+};
+
+void daemonize_fs_struct(void)
+{
+ struct fs_struct *fs;
+
+ exit_fs(current); /* current->fs->count--; */
+ fs = &init_fs;
+ current->fs = fs;
+ atomic_inc(&fs->count);
+}