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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-05 10:46:40 +07:00
ea5b778a8b
Unexport do_add_mount() and make ->d_automount() return the vfsmount to be added rather than calling do_add_mount() itself. follow_automount() will then do the addition. This slightly complicates things as ->d_automount() normally wants to add the new vfsmount to an expiration list and start an expiration timer. The problem with that is that the vfsmount will be deleted if it has a refcount of 1 and the timer will not repeat if the expiration list is empty. To this end, we require the vfsmount to be returned from d_automount() with a refcount of (at least) 2. One of these refs will be dropped unconditionally. In addition, follow_automount() must get a 3rd ref around the call to do_add_mount() lest it eat a ref and return an error, leaving the mount we have open to being expired as we would otherwise have only 1 ref on it. d_automount() should also add the the vfsmount to the expiration list (by calling mnt_set_expiry()) and start the expiration timer before returning, if this mechanism is to be used. The vfsmount will be unlinked from the expiration list by follow_automount() if do_add_mount() fails. This patch also fixes the call to do_add_mount() for AFS to propagate the mount flags from the parent vfsmount. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
285 lines
6.8 KiB
C
285 lines
6.8 KiB
C
/* 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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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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 "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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struct nameidata *nd);
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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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/*
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* check a symbolic link to see whether it actually encodes a mountpoint
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* - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
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*/
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int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
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{
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struct page *page;
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size_t size;
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char *buf;
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int ret;
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_enter("{%x:%u,%u}",
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vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
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/* read the contents of the symlink into the pagecache */
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page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
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afs_page_filler, key);
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if (IS_ERR(page)) {
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ret = PTR_ERR(page);
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goto out;
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}
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ret = -EIO;
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if (PageError(page))
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goto out_free;
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buf = kmap(page);
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/* examine the symlink's contents */
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size = vnode->status.size;
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_debug("symlink to %*.*s", (int) size, (int) size, buf);
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if (size > 2 &&
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(buf[0] == '%' || buf[0] == '#') &&
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buf[size - 1] == '.'
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) {
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_debug("symlink is a mountpoint");
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spin_lock(&vnode->lock);
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set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
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vnode->vfs_inode.i_flags |= S_AUTOMOUNT;
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spin_unlock(&vnode->lock);
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}
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ret = 0;
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kunmap(page);
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out_free:
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page_cache_release(page);
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out:
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_leave(" = %d", ret);
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return ret;
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}
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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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struct nameidata *nd)
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{
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_enter("%p,%p{%p{%s},%s}",
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dir,
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dentry,
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dentry->d_parent,
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dentry->d_parent ?
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dentry->d_parent->d_name.name : (const unsigned char *) "",
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dentry->d_name.name);
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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{%p{%s},%s}",
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inode, file,
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file->f_path.dentry->d_parent,
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file->f_path.dentry->d_parent ?
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file->f_path.dentry->d_parent->d_name.name :
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(const unsigned char *) "",
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file->f_path.dentry->d_name.name);
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return -EREMOTE;
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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 afs_super_info *super;
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struct vfsmount *mnt;
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struct afs_vnode *vnode;
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struct page *page;
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char *devname, *options;
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bool rwpath = false;
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int ret;
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_enter("{%s}", mntpt->d_name.name);
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BUG_ON(!mntpt->d_inode);
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ret = -ENOMEM;
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devname = (char *) get_zeroed_page(GFP_KERNEL);
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if (!devname)
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goto error_no_devname;
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options = (char *) get_zeroed_page(GFP_KERNEL);
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if (!options)
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goto error_no_options;
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vnode = AFS_FS_I(mntpt->d_inode);
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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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static const char afs_root_cell[] = ":root.cell.";
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unsigned size = mntpt->d_name.len;
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ret = -ENOENT;
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if (size < 2 || size > AFS_MAXCELLNAME)
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goto error_no_page;
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if (mntpt->d_name.name[0] == '.') {
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devname[0] = '#';
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memcpy(devname + 1, mntpt->d_name.name, size - 1);
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memcpy(devname + size, afs_root_cell,
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sizeof(afs_root_cell));
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rwpath = true;
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} else {
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devname[0] = '%';
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memcpy(devname + 1, mntpt->d_name.name, size);
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memcpy(devname + size + 1, afs_root_cell,
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sizeof(afs_root_cell));
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}
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} else {
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/* read the contents of the AFS special symlink */
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loff_t size = i_size_read(mntpt->d_inode);
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char *buf;
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ret = -EINVAL;
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if (size > PAGE_SIZE - 1)
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goto error_no_page;
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page = read_mapping_page(mntpt->d_inode->i_mapping, 0, NULL);
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if (IS_ERR(page)) {
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ret = PTR_ERR(page);
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goto error_no_page;
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}
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ret = -EIO;
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if (PageError(page))
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goto error;
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buf = kmap_atomic(page, KM_USER0);
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memcpy(devname, buf, size);
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kunmap_atomic(buf, KM_USER0);
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page_cache_release(page);
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page = NULL;
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}
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/* work out what options we want */
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super = AFS_FS_S(mntpt->d_sb);
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memcpy(options, "cell=", 5);
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strcpy(options + 5, super->volume->cell->name);
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if (super->volume->type == AFSVL_RWVOL || rwpath)
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strcat(options, ",rwpath");
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/* try and do the mount */
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_debug("--- attempting mount %s -o %s ---", devname, options);
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mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
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_debug("--- mount result %p ---", mnt);
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free_page((unsigned long) devname);
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free_page((unsigned long) options);
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_leave(" = %p", mnt);
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return mnt;
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error:
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page_cache_release(page);
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error_no_page:
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free_page((unsigned long) options);
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error_no_options:
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free_page((unsigned long) devname);
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error_no_devname:
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_leave(" = %d", ret);
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return ERR_PTR(ret);
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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("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name);
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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 {%s}", newmnt, newmnt->mnt_devname);
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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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