// SPDX-License-Identifier: GPL-2.0-or-later
/* CacheFiles extended attribute management
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*/
#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"
#define CACHEFILES_COOKIE_TYPE_DATA 1
struct cachefiles_xattr {
__be64 object_size; /* Actual size of the object */
__be64 zero_point; /* Size after which server has no data not written by us */
__u8 type; /* Type of object */
__u8 content; /* Content presence (enum cachefiles_content) */
__u8 data[]; /* netfs coherency data */
} __packed;
static const char cachefiles_xattr_cache[] =
XATTR_USER_PREFIX "CacheFiles.cache";
struct cachefiles_vol_xattr {
__be32 reserved; /* Reserved, should be 0 */
__u8 data[]; /* netfs volume coherency data */
} __packed;
/*
* set the state xattr on a cache file
*/
int cachefiles_set_object_xattr(struct cachefiles_object *object)
{
struct cachefiles_xattr *buf;
struct dentry *dentry;
struct file *file = object->file;
unsigned int len = object->cookie->aux_len;
int ret;
if (!file)
return -ESTALE;
dentry = file->f_path.dentry;
_enter("%x,#%d", object->debug_id, len);
buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
buf->object_size = cpu_to_be64(object->cookie->object_size);
buf->zero_point = 0;
buf->type = CACHEFILES_COOKIE_TYPE_DATA;
buf->content = object->content_info;
if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
buf->content = CACHEFILES_CONTENT_DIRTY;
if (len > 0)
memcpy(buf->data, fscache_get_aux(object->cookie), len);
ret = cachefiles_inject_write_error();
if (ret == 0) {
ret = mnt_want_write_file(file);
if (ret == 0) {
ret = vfs_setxattr(&nop_mnt_idmap, dentry,
cachefiles_xattr_cache, buf,
sizeof(struct cachefiles_xattr) + len, 0);
mnt_drop_write_file(file);
}
}
if (ret < 0) {
trace_cachefiles_vfs_error(object, file_inode(file), ret,
cachefiles_trace_setxattr_error);
trace_cachefiles_coherency(object, file_inode(file)->i_ino,
buf->content,
cachefiles_coherency_set_fail);
if (ret != -ENOMEM)
cachefiles_io_error_obj(
object,
"Failed to set xattr with error %d", ret);
} else {
trace_cachefiles_coherency(object, file_inode(file)->i_ino,
buf->content,
cachefiles_coherency_set_ok);
}
kfree(buf);
_leave(" = %d", ret);
return ret;
}
/*
* check the consistency between the backing cache and the FS-Cache cookie
*/
int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file)
{
struct cachefiles_xattr *buf;
struct dentry *dentry = file->f_path.dentry;
unsigned int len = object->cookie->aux_len, tlen;
const void *p = fscache_get_aux(object->cookie);
enum cachefiles_coherency_trace why;
ssize_t xlen;
int ret = -ESTALE;
tlen = sizeof(struct cachefiles_xattr) + len;
buf = kmalloc(tlen, GFP_KERNEL);
if (!buf)
return -ENOMEM;
xlen = cachefiles_inject_read_error();
if (xlen == 0)
xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen);
if (xlen != tlen) {
if (xlen < 0) {
ret = xlen;
trace_cachefiles_vfs_error(object, file_inode(file), xlen,
cachefiles_trace_getxattr_error);
}
if (xlen == -EIO)
cachefiles_io_error_obj(
object,
"Failed to read aux with error %zd", xlen);
why = cachefiles_coherency_check_xattr;
} else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) {
why = cachefiles_coherency_check_type;
} else if (memcmp(buf->data, p, len) != 0) {
why = cachefiles_coherency_check_aux;
} else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) {
why = cachefiles_coherency_check_objsize;
} else if (buf->content == CACHEFILES_CONTENT_DIRTY) {
// TODO: Begin conflict resolution
pr_warn("Dirty object in cache\n");
why = cachefiles_coherency_check_dirty;
} else {
why = cachefiles_coherency_check_ok;
ret = 0;
}
trace_cachefiles_coherency(object, file_inode(file)->i_ino,
buf->content, why);
kfree(buf);
return ret;
}
/*
* remove the object's xattr to mark it stale
*/
int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
struct cachefiles_object *object,
struct dentry *dentry)
{
int ret;
ret = cachefiles_inject_remove_error();
if (ret == 0) {
ret = mnt_want_write(cache->mnt);
if (ret == 0) {
ret = vfs_removexattr(&nop_mnt_idmap, dentry,
cachefiles_xattr_cache);
mnt_drop_write(cache->mnt);
}
}
if (ret < 0) {
trace_cachefiles_vfs_error(object, d_inode(dentry), ret,
cachefiles_trace_remxattr_error);
if (ret == -ENOENT || ret == -ENODATA)
ret = 0;
else if (ret != -ENOMEM)
cachefiles_io_error(cache,
"Can't remove xattr from %lu"
" (error %d)",
d_backing_inode(dentry)->i_ino, -ret);
}
_leave(" = %d", ret);
return ret;
}
/*
* Stick a marker on the cache object to indicate that it's dirty.
*/
void cachefiles_prepare_to_write(struct fscache_cookie *cookie)
{
const struct cred *saved_cred;
struct cachefiles_object *object = cookie->cache_priv;
struct cachefiles_cache *cache = object->volume->cache;
_enter("c=%08x", object->cookie->debug_id);
if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
cachefiles_begin_secure(cache, &saved_cred);
cachefiles_set_object_xattr(object);
cachefiles_end_secure(cache, saved_cred);
}
}
/*
* Set the state xattr on a volume directory.
*/
bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
{
struct cachefiles_vol_xattr *buf;
unsigned int len = volume->vcookie->coherency_len;
const void *p = volume->vcookie->coherency;
struct dentry *dentry = volume->dentry;
int ret;
_enter("%x,#%d", volume->vcookie->debug_id, len);
len += sizeof(*buf);
buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return false;
buf->reserved = cpu_to_be32(0);
memcpy(buf->data, p, volume->vcookie->coherency_len);
ret = cachefiles_inject_write_error();
if (ret == 0) {
ret = mnt_want_write(volume->cache->mnt);
if (ret == 0) {
ret = vfs_setxattr(&nop_mnt_idmap, dentry,
cachefiles_xattr_cache,
buf, len, 0);
mnt_drop_write(volume->cache->mnt);
}
}
if (ret < 0) {
trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret,
cachefiles_trace_setxattr_error);
trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
cachefiles_coherency_vol_set_fail);
if (ret != -ENOMEM)
cachefiles_io_error(
volume->cache, "Failed to set xattr with error %d", ret);
} else {
trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
cachefiles_coherency_vol_set_ok);
}
kfree(buf);
_leave(" = %d", ret);
return ret == 0;
}
/*
* Check the consistency between the backing cache and the volume cookie.
*/
int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
{
struct cachefiles_vol_xattr *buf;
struct dentry *dentry = volume->dentry;
unsigned int len = volume->vcookie->coherency_len;
const void *p = volume->vcookie->coherency;
enum cachefiles_coherency_trace why;
ssize_t xlen;
int ret = -ESTALE;
_enter("");
len += sizeof(*buf);
buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
xlen = cachefiles_inject_read_error();
if (xlen == 0)
xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len);
if (xlen != len) {
if (xlen < 0) {
ret = xlen;
trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
cachefiles_trace_getxattr_error);
if (xlen == -EIO)
cachefiles_io_error(
volume->cache,
"Failed to read xattr with error %zd", xlen);
}
why = cachefiles_coherency_vol_check_xattr;
} else if (buf->reserved != cpu_to_be32(0)) {
why = cachefiles_coherency_vol_check_resv;
} else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) {
why = cachefiles_coherency_vol_check_cmp;
} else {
why = cachefiles_coherency_vol_check_ok;
ret = 0;
}
trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why);
kfree(buf);
_leave(" = %d", ret);
return ret;
}
Codebase Browser
linux