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// SPDX-License-Identifier: GPL-2.0-or-later
/* mountpoint management
*
* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/gfp.h>
#include <linux/fs_context.h>
#include "internal.h"
static struct dentry *afs_mntpt_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags);
static int afs_mntpt_open(struct inode *inode, struct file *file);
static void afs_mntpt_expiry_timed_out(struct work_struct *work);
const struct file_operations afs_mntpt_file_operations = {
.open = afs_mntpt_open,
.llseek = noop_llseek,
};
const struct inode_operations afs_mntpt_inode_operations = {
.lookup = afs_mntpt_lookup,
.readlink = page_readlink,
.getattr = afs_getattr,
};
const struct inode_operations afs_autocell_inode_operations = {
.getattr = afs_getattr,
};
static LIST_HEAD(afs_vfsmounts);
static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
static const char afs_root_volume[] = "root.cell";
/*
* no valid lookup procedure on this sort of dir
*/
static struct dentry *afs_mntpt_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags)
{
_enter("%p,%p{%pd2}", dir, dentry, dentry);
return ERR_PTR(-EREMOTE);
}
/*
* no valid open procedure on this sort of dir
*/
static int afs_mntpt_open(struct inode *inode, struct file *file)
{
_enter("%p,%p{%pD2}", inode, file, file);
return -EREMOTE;
}
/*
* Set the parameters for the proposed superblock.
*/
static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
{
struct afs_fs_context *ctx = fc->fs_private;
struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
struct afs_cell *cell;
const char *p;
int ret;
if (fc->net_ns != src_as->net_ns) {
put_net(fc->net_ns);
fc->net_ns = get_net(src_as->net_ns);
}
if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
ctx->type = AFSVL_RWVOL;
ctx->force = true;
}
if (ctx->cell) {
afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_mntpt);
ctx->cell = NULL;
}
if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
/* if the directory is a pseudo directory, use the d_name */
unsigned size = mntpt->d_name.len;
if (size < 2)
return -ENOENT;
p = mntpt->d_name.name;
if (mntpt->d_name.name[0] == '.') {
size--;
p++;
ctx->type = AFSVL_RWVOL;
ctx->force = true;
}
if (size > AFS_MAXCELLNAME)
return -ENAMETOOLONG;
cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
if (IS_ERR(cell)) {
pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
return PTR_ERR(cell);
}
ctx->cell = cell;
ctx->volname = afs_root_volume;
ctx->volnamesz = sizeof(afs_root_volume) - 1;
} else {
/* read the contents of the AFS special symlink */
struct page *page;
loff_t size = i_size_read(d_inode(mntpt));
char *buf;
if (src_as->cell)
ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt);
if (size < 2 || size > PAGE_SIZE - 1)
return -EINVAL;
page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
if (IS_ERR(page))
return PTR_ERR(page);
buf = kmap(page);
ret = -EINVAL;
if (buf[size - 1] == '.')
ret = vfs_parse_fs_string(fc, "source", buf, size - 1);
kunmap(page);
put_page(page);
if (ret < 0)
return ret;
/* Don't cross a backup volume mountpoint from a backup volume */
if (src_as->volume && src_as->volume->type == AFSVL_BACKVOL &&
ctx->type == AFSVL_BACKVOL)
return -ENODEV;
}
return 0;
}
/*
* create a vfsmount to be automounted
*/
static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
{
struct fs_context *fc;
struct vfsmount *mnt;
int ret;
BUG_ON(!d_inode(mntpt));
fc = fs_context_for_submount(&afs_fs_type, mntpt);
if (IS_ERR(fc))
return ERR_CAST(fc);
ret = afs_mntpt_set_params(fc, mntpt);
if (!ret)
mnt = fc_mount(fc);
else
mnt = ERR_PTR(ret);
put_fs_context(fc);
return mnt;
}
/*
* handle an automount point
*/
struct vfsmount *afs_d_automount(struct path *path)
{
struct vfsmount *newmnt;
_enter("{%pd}", path->dentry);
newmnt = afs_mntpt_do_automount(path->dentry);
if (IS_ERR(newmnt))
return newmnt;
mntget(newmnt); /* prevent immediate expiration */
mnt_set_expiry(newmnt, &afs_vfsmounts);
queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
afs_mntpt_expiry_timeout * HZ);
_leave(" = %p", newmnt);
return newmnt;
}
/*
* handle mountpoint expiry timer going off
*/
static void afs_mntpt_expiry_timed_out(struct work_struct *work)
{
_enter("");
if (!list_empty(&afs_vfsmounts)) {
mark_mounts_for_expiry(&afs_vfsmounts);
queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
afs_mntpt_expiry_timeout * HZ);
}
_leave("");
}
/*
* kill the AFS mountpoint timer if it's still running
*/
void afs_mntpt_kill_timer(void)
{
_enter("");
ASSERT(list_empty(&afs_vfsmounts));
cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
}
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