3e93cd6718
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>
142 lines
2.8 KiB
C
142 lines
2.8 KiB
C
#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/path.h>
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#include <linux/slab.h>
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/*
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* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
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* It can block.
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*/
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void set_fs_root(struct fs_struct *fs, struct path *path)
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{
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struct path old_root;
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write_lock(&fs->lock);
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old_root = fs->root;
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fs->root = *path;
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path_get(path);
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write_unlock(&fs->lock);
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if (old_root.dentry)
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path_put(&old_root);
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}
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/*
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* Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
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* It can block.
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*/
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void set_fs_pwd(struct fs_struct *fs, struct path *path)
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{
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struct path old_pwd;
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write_lock(&fs->lock);
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old_pwd = fs->pwd;
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fs->pwd = *path;
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path_get(path);
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write_unlock(&fs->lock);
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if (old_pwd.dentry)
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path_put(&old_pwd);
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}
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void chroot_fs_refs(struct path *old_root, struct path *new_root)
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{
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struct task_struct *g, *p;
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struct fs_struct *fs;
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int count = 0;
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read_lock(&tasklist_lock);
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do_each_thread(g, p) {
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task_lock(p);
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fs = p->fs;
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if (fs) {
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write_lock(&fs->lock);
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if (fs->root.dentry == old_root->dentry
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&& fs->root.mnt == old_root->mnt) {
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path_get(new_root);
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fs->root = *new_root;
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count++;
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}
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if (fs->pwd.dentry == old_root->dentry
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&& fs->pwd.mnt == old_root->mnt) {
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path_get(new_root);
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fs->pwd = *new_root;
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count++;
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}
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write_unlock(&fs->lock);
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}
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task_unlock(p);
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} while_each_thread(g, p);
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read_unlock(&tasklist_lock);
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while (count--)
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path_put(old_root);
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}
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void put_fs_struct(struct fs_struct *fs)
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{
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/* No need to hold fs->lock if we are killing it */
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if (atomic_dec_and_test(&fs->count)) {
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path_put(&fs->root);
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path_put(&fs->pwd);
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kmem_cache_free(fs_cachep, fs);
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}
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}
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void exit_fs(struct task_struct *tsk)
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{
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struct fs_struct * fs = tsk->fs;
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if (fs) {
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task_lock(tsk);
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tsk->fs = NULL;
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task_unlock(tsk);
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put_fs_struct(fs);
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}
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}
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struct fs_struct *copy_fs_struct(struct fs_struct *old)
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{
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struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
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/* We don't need to lock fs - think why ;-) */
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if (fs) {
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atomic_set(&fs->count, 1);
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rwlock_init(&fs->lock);
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fs->umask = old->umask;
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read_lock(&old->lock);
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fs->root = old->root;
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path_get(&old->root);
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fs->pwd = old->pwd;
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path_get(&old->pwd);
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read_unlock(&old->lock);
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}
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return fs;
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}
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int unshare_fs_struct(void)
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{
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struct fs_struct *fsp = copy_fs_struct(current->fs);
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if (!fsp)
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return -ENOMEM;
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exit_fs(current);
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current->fs = fsp;
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return 0;
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}
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EXPORT_SYMBOL_GPL(unshare_fs_struct);
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/* to be mentioned only in INIT_TASK */
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struct fs_struct init_fs = {
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.count = ATOMIC_INIT(1),
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.lock = __RW_LOCK_UNLOCKED(init_fs.lock),
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.umask = 0022,
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};
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void daemonize_fs_struct(void)
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{
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struct fs_struct *fs;
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exit_fs(current); /* current->fs->count--; */
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fs = &init_fs;
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current->fs = fs;
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atomic_inc(&fs->count);
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}
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