original development tree for Linux kernel GTP module; now long in mainline.
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/* CacheFiles extended attribute management
*
* Copyright (C) 2007 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/module.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/quotaops.h>
#include <linux/xattr.h>
#include <linux/slab.h>
#include "internal.h"
static const char cachefiles_xattr_cache[] =
XATTR_USER_PREFIX "CacheFiles.cache";
/*
* check the type label on an object
* - done using xattrs
*/
int cachefiles_check_object_type(struct cachefiles_object *object)
{
struct dentry *dentry = object->dentry;
char type[3], xtype[3];
int ret;
ASSERT(dentry);
ASSERT(dentry->d_inode);
if (!object->fscache.cookie)
strcpy(type, "C3");
else
snprintf(type, 3, "%02x", object->fscache.cookie->def->type);
_enter("%p{%s}", object, type);
/* attempt to install a type label directly */
ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2,
XATTR_CREATE);
if (ret == 0) {
_debug("SET"); /* we succeeded */
goto error;
}
if (ret != -EEXIST) {
kerror("Can't set xattr on %*.*s [%lu] (err %d)",
dentry->d_name.len, dentry->d_name.len,
dentry->d_name.name, dentry->d_inode->i_ino,
-ret);
goto error;
}
/* read the current type label */
ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3);
if (ret < 0) {
if (ret == -ERANGE)
goto bad_type_length;
kerror("Can't read xattr on %*.*s [%lu] (err %d)",
dentry->d_name.len, dentry->d_name.len,
dentry->d_name.name, dentry->d_inode->i_ino,
-ret);
goto error;
}
/* check the type is what we're expecting */
if (ret != 2)
goto bad_type_length;
if (xtype[0] != type[0] || xtype[1] != type[1])
goto bad_type;
ret = 0;
error:
_leave(" = %d", ret);
return ret;
bad_type_length:
kerror("Cache object %lu type xattr length incorrect",
dentry->d_inode->i_ino);
ret = -EIO;
goto error;
bad_type:
xtype[2] = 0;
kerror("Cache object %*.*s [%lu] type %s not %s",
dentry->d_name.len, dentry->d_name.len,
dentry->d_name.name, dentry->d_inode->i_ino,
xtype, type);
ret = -EIO;
goto error;
}
/*
* set the state xattr on a cache file
*/
int cachefiles_set_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata)
{
struct dentry *dentry = object->dentry;
int ret;
ASSERT(object->fscache.cookie);
ASSERT(dentry);
_enter("%p,#%d", object, auxdata->len);
/* attempt to install the cache metadata directly */
_debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
&auxdata->type, auxdata->len,
XATTR_CREATE);
if (ret < 0 && ret != -ENOMEM)
cachefiles_io_error_obj(
object,
"Failed to set xattr with error %d", ret);
_leave(" = %d", ret);
return ret;
}
/*
* update the state xattr on a cache file
*/
int cachefiles_update_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata)
{
struct dentry *dentry = object->dentry;
int ret;
ASSERT(object->fscache.cookie);
ASSERT(dentry);
_enter("%p,#%d", object, auxdata->len);
/* attempt to install the cache metadata directly */
_debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
&auxdata->type, auxdata->len,
XATTR_REPLACE);
if (ret < 0 && ret != -ENOMEM)
cachefiles_io_error_obj(
object,
"Failed to update xattr with error %d", ret);
_leave(" = %d", ret);
return ret;
}
/*
* check the state xattr on a cache file
* - return -ESTALE if the object should be deleted
*/
int cachefiles_check_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata)
{
struct cachefiles_xattr *auxbuf;
struct dentry *dentry = object->dentry;
int ret;
_enter("%p,#%d", object, auxdata->len);
ASSERT(dentry);
ASSERT(dentry->d_inode);
auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp);
if (!auxbuf) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
/* read the current type label */
ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
&auxbuf->type, 512 + 1);
if (ret < 0) {
if (ret == -ENODATA)
goto stale; /* no attribute - power went off
* mid-cull? */
if (ret == -ERANGE)
goto bad_type_length;
cachefiles_io_error_obj(object,
"Can't read xattr on %lu (err %d)",
dentry->d_inode->i_ino, -ret);
goto error;
}
/* check the on-disk object */
if (ret < 1)
goto bad_type_length;
if (auxbuf->type != auxdata->type)
goto stale;
auxbuf->len = ret;
/* consult the netfs */
if (object->fscache.cookie->def->check_aux) {
enum fscache_checkaux result;
unsigned int dlen;
dlen = auxbuf->len - 1;
_debug("checkaux %s #%u",
object->fscache.cookie->def->name, dlen);
result = fscache_check_aux(&object->fscache,
&auxbuf->data, dlen);
switch (result) {
/* entry okay as is */
case FSCACHE_CHECKAUX_OKAY:
goto okay;
/* entry requires update */
case FSCACHE_CHECKAUX_NEEDS_UPDATE:
break;
/* entry requires deletion */
case FSCACHE_CHECKAUX_OBSOLETE:
goto stale;
default:
BUG();
}
/* update the current label */
ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
&auxdata->type, auxdata->len,
XATTR_REPLACE);
if (ret < 0) {
cachefiles_io_error_obj(object,
"Can't update xattr on %lu"
" (error %d)",
dentry->d_inode->i_ino, -ret);
goto error;
}
}
okay:
ret = 0;
error:
kfree(auxbuf);
_leave(" = %d", ret);
return ret;
bad_type_length:
kerror("Cache object %lu xattr length incorrect",
dentry->d_inode->i_ino);
ret = -EIO;
goto error;
stale:
ret = -ESTALE;
goto error;
}
/*
* remove the object's xattr to mark it stale
*/
int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
struct dentry *dentry)
{
int ret;
ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
if (ret < 0) {
if (ret == -ENOENT || ret == -ENODATA)
ret = 0;
else if (ret != -ENOMEM)
cachefiles_io_error(cache,
"Can't remove xattr from %lu"
" (error %d)",
dentry->d_inode->i_ino, -ret);
}
_leave(" = %d", ret);
return ret;
}