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/* Extended attribute handling for AFS. We use xattrs to get and set metadata
* instead of providing pioctl().
*
* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/xattr.h>
#include "internal.h"
static const char afs_xattr_list[] =
"afs.cell\0"
"afs.fid\0"
"afs.volume";
/*
* Retrieve a list of the supported xattrs.
*/
ssize_t afs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
if (size == 0)
return sizeof(afs_xattr_list);
if (size < sizeof(afs_xattr_list))
return -ERANGE;
memcpy(buffer, afs_xattr_list, sizeof(afs_xattr_list));
return sizeof(afs_xattr_list);
}
/*
* Get the name of the cell on which a file resides.
*/
static int afs_xattr_get_cell(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_cell *cell = vnode->volume->cell;
size_t namelen;
namelen = cell->name_len;
if (size == 0)
return namelen;
if (namelen > size)
return -ERANGE;
memcpy(buffer, cell->name, namelen);
return namelen;
}
static const struct xattr_handler afs_xattr_afs_cell_handler = {
.name = "afs.cell",
.get = afs_xattr_get_cell,
};
/*
* Get the volume ID, vnode ID and vnode uniquifier of a file as a sequence of
* hex numbers separated by colons.
*/
static int afs_xattr_get_fid(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_vnode *vnode = AFS_FS_I(inode);
char text[16 + 1 + 24 + 1 + 8 + 1];
size_t len;
/* The volume ID is 64-bit, the vnode ID is 96-bit and the
* uniquifier is 32-bit.
*/
len = sprintf(text, "%llx:", vnode->fid.vid);
if (vnode->fid.vnode_hi)
len += sprintf(text + len, "%x%016llx",
vnode->fid.vnode_hi, vnode->fid.vnode);
else
len += sprintf(text + len, "%llx", vnode->fid.vnode);
len += sprintf(text + len, ":%x", vnode->fid.unique);
if (size == 0)
return len;
if (len > size)
return -ERANGE;
memcpy(buffer, text, len);
return len;
}
static const struct xattr_handler afs_xattr_afs_fid_handler = {
.name = "afs.fid",
.get = afs_xattr_get_fid,
};
/*
* Get the name of the volume on which a file resides.
*/
static int afs_xattr_get_volume(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_vnode *vnode = AFS_FS_I(inode);
const char *volname = vnode->volume->name;
size_t namelen;
namelen = strlen(volname);
if (size == 0)
return namelen;
if (namelen > size)
return -ERANGE;
memcpy(buffer, volname, namelen);
return namelen;
}
static const struct xattr_handler afs_xattr_afs_volume_handler = {
.name = "afs.volume",
.get = afs_xattr_get_volume,
};
const struct xattr_handler *afs_xattr_handlers[] = {
&afs_xattr_afs_cell_handler,
&afs_xattr_afs_fid_handler,
&afs_xattr_afs_volume_handler,
NULL
};
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