// SPDX-License-Identifier: GPL-2.0-or-later
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/* mountpoint management
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*
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* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/gfp.h>
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#include <linux/fs_context.h>
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#include "internal.h"
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags);
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static int afs_mntpt_open(struct inode *inode, struct file *file);
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static void afs_mntpt_expiry_timed_out(struct work_struct *work);
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const struct file_operations afs_mntpt_file_operations = {
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.open = afs_mntpt_open,
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.llseek = noop_llseek,
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};
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const struct inode_operations afs_mntpt_inode_operations = {
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.lookup = afs_mntpt_lookup,
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.readlink = page_readlink,
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.getattr = afs_getattr,
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};
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const struct inode_operations afs_autocell_inode_operations = {
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.getattr = afs_getattr,
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};
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static LIST_HEAD(afs_vfsmounts);
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static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
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static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
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static const char afs_root_volume[] = "root.cell";
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/*
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* no valid lookup procedure on this sort of dir
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*/
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags)
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{
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_enter("%p,%p{%pd2}", dir, dentry, dentry);
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return ERR_PTR(-EREMOTE);
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}
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/*
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* no valid open procedure on this sort of dir
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*/
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static int afs_mntpt_open(struct inode *inode, struct file *file)
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{
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_enter("%p,%p{%pD2}", inode, file, file);
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return -EREMOTE;
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}
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/*
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* Set the parameters for the proposed superblock.
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*/
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static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
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{
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struct afs_fs_context *ctx = fc->fs_private;
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struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
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struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
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struct afs_cell *cell;
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const char *p;
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int ret;
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if (fc->net_ns != src_as->net_ns) {
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put_net(fc->net_ns);
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fc->net_ns = get_net(src_as->net_ns);
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}
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if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
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ctx->type = AFSVL_RWVOL;
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ctx->force = true;
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}
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if (ctx->cell) {
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afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_mntpt);
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ctx->cell = NULL;
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}
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if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
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/* if the directory is a pseudo directory, use the d_name */
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unsigned size = mntpt->d_name.len;
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if (size < 2)
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return -ENOENT;
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p = mntpt->d_name.name;
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if (mntpt->d_name.name[0] == '.') {
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size--;
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p++;
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ctx->type = AFSVL_RWVOL;
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ctx->force = true;
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}
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if (size > AFS_MAXCELLNAME)
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return -ENAMETOOLONG;
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cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
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if (IS_ERR(cell)) {
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pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
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return PTR_ERR(cell);
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}
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ctx->cell = cell;
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ctx->volname = afs_root_volume;
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ctx->volnamesz = sizeof(afs_root_volume) - 1;
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} else {
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/* read the contents of the AFS special symlink */
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struct page *page;
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loff_t size = i_size_read(d_inode(mntpt));
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char *buf;
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if (src_as->cell)
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ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt);
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if (size < 2 || size > PAGE_SIZE - 1)
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return -EINVAL;
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page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
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if (IS_ERR(page))
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return PTR_ERR(page);
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if (PageError(page)) {
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ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt);
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put_page(page);
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return ret;
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}
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buf = kmap(page);
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ret = -EINVAL;
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if (buf[size - 1] == '.')
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ret = vfs_parse_fs_string(fc, "source", buf, size - 1);
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kunmap(page);
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put_page(page);
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if (ret < 0)
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return ret;
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}
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return 0;
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}
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/*
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* create a vfsmount to be automounted
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*/
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static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
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{
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struct fs_context *fc;
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struct vfsmount *mnt;
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int ret;
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BUG_ON(!d_inode(mntpt));
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fc = fs_context_for_submount(&afs_fs_type, mntpt);
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if (IS_ERR(fc))
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return ERR_CAST(fc);
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ret = afs_mntpt_set_params(fc, mntpt);
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if (!ret)
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mnt = fc_mount(fc);
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else
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mnt = ERR_PTR(ret);
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put_fs_context(fc);
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return mnt;
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}
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/*
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* handle an automount point
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*/
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struct vfsmount *afs_d_automount(struct path *path)
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{
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struct vfsmount *newmnt;
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_enter("{%pd}", path->dentry);
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newmnt = afs_mntpt_do_automount(path->dentry);
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if (IS_ERR(newmnt))
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return newmnt;
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mntget(newmnt); /* prevent immediate expiration */
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mnt_set_expiry(newmnt, &afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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_leave(" = %p", newmnt);
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return newmnt;
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}
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/*
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* handle mountpoint expiry timer going off
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*/
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static void afs_mntpt_expiry_timed_out(struct work_struct *work)
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{
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_enter("");
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if (!list_empty(&afs_vfsmounts)) {
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mark_mounts_for_expiry(&afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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}
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_leave("");
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}
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/*
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* kill the AFS mountpoint timer if it's still running
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*/
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void afs_mntpt_kill_timer(void)
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{
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_enter("");
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ASSERT(list_empty(&afs_vfsmounts));
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cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
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}
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