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fs/fs_struct.c
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#include <linux/module.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/path.h> #include <linux/slab.h> |
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#include <linux/fs_struct.h> |
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/* * 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); } |
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void free_fs_struct(struct fs_struct *fs) |
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{ |
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path_put(&fs->root); path_put(&fs->pwd); kmem_cache_free(fs_cachep, fs); |
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} void exit_fs(struct task_struct *tsk) { |
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struct fs_struct *fs = tsk->fs; |
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if (fs) { |
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int kill; |
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task_lock(tsk); |
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write_lock(&fs->lock); |
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tsk->fs = NULL; |
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kill = !--fs->users; write_unlock(&fs->lock); |
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task_unlock(tsk); |
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if (kill) free_fs_struct(fs); |
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} } 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) { |
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fs->users = 1; fs->in_exec = 0; |
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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) { |
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struct fs_struct *fs = current->fs; struct fs_struct *new_fs = copy_fs_struct(fs); int kill; if (!new_fs) |
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return -ENOMEM; |
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task_lock(current); write_lock(&fs->lock); kill = !--fs->users; current->fs = new_fs; write_unlock(&fs->lock); task_unlock(current); if (kill) free_fs_struct(fs); |
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return 0; } EXPORT_SYMBOL_GPL(unshare_fs_struct); |
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int current_umask(void) { return current->fs->umask; } EXPORT_SYMBOL(current_umask); |
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/* to be mentioned only in INIT_TASK */ struct fs_struct init_fs = { |
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.users = 1, |
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.lock = __RW_LOCK_UNLOCKED(init_fs.lock), .umask = 0022, }; void daemonize_fs_struct(void) { |
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struct fs_struct *fs = current->fs; if (fs) { int kill; task_lock(current); |
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write_lock(&init_fs.lock); init_fs.users++; write_unlock(&init_fs.lock); write_lock(&fs->lock); current->fs = &init_fs; kill = !--fs->users; write_unlock(&fs->lock); task_unlock(current); if (kill) free_fs_struct(fs); } |
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} |