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![Christian Brauner](/assets/img/avatar_default.png)
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b
("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
276 lines
7.7 KiB
C
276 lines
7.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* CacheFiles extended attribute management
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*
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* Copyright (C) 2021 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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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/fsnotify.h>
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#include <linux/quotaops.h>
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#include <linux/xattr.h>
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#include <linux/slab.h>
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#include "internal.h"
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#define CACHEFILES_COOKIE_TYPE_DATA 1
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struct cachefiles_xattr {
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__be64 object_size; /* Actual size of the object */
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__be64 zero_point; /* Size after which server has no data not written by us */
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__u8 type; /* Type of object */
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__u8 content; /* Content presence (enum cachefiles_content) */
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__u8 data[]; /* netfs coherency data */
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} __packed;
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static const char cachefiles_xattr_cache[] =
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XATTR_USER_PREFIX "CacheFiles.cache";
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struct cachefiles_vol_xattr {
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__be32 reserved; /* Reserved, should be 0 */
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__u8 data[]; /* netfs volume coherency data */
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} __packed;
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/*
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* set the state xattr on a cache file
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*/
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int cachefiles_set_object_xattr(struct cachefiles_object *object)
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{
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struct cachefiles_xattr *buf;
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struct dentry *dentry;
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struct file *file = object->file;
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unsigned int len = object->cookie->aux_len;
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int ret;
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if (!file)
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return -ESTALE;
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dentry = file->f_path.dentry;
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_enter("%x,#%d", object->debug_id, len);
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buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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buf->object_size = cpu_to_be64(object->cookie->object_size);
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buf->zero_point = 0;
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buf->type = CACHEFILES_COOKIE_TYPE_DATA;
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buf->content = object->content_info;
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if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
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buf->content = CACHEFILES_CONTENT_DIRTY;
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if (len > 0)
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memcpy(buf->data, fscache_get_aux(object->cookie), len);
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ret = cachefiles_inject_write_error();
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if (ret == 0)
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ret = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache,
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buf, sizeof(struct cachefiles_xattr) + len, 0);
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if (ret < 0) {
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trace_cachefiles_vfs_error(object, file_inode(file), ret,
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cachefiles_trace_setxattr_error);
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trace_cachefiles_coherency(object, file_inode(file)->i_ino,
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buf->content,
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cachefiles_coherency_set_fail);
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if (ret != -ENOMEM)
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cachefiles_io_error_obj(
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object,
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"Failed to set xattr with error %d", ret);
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} else {
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trace_cachefiles_coherency(object, file_inode(file)->i_ino,
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buf->content,
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cachefiles_coherency_set_ok);
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}
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kfree(buf);
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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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* check the consistency between the backing cache and the FS-Cache cookie
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*/
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int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file)
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{
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struct cachefiles_xattr *buf;
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struct dentry *dentry = file->f_path.dentry;
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unsigned int len = object->cookie->aux_len, tlen;
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const void *p = fscache_get_aux(object->cookie);
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enum cachefiles_coherency_trace why;
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ssize_t xlen;
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int ret = -ESTALE;
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tlen = sizeof(struct cachefiles_xattr) + len;
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buf = kmalloc(tlen, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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xlen = cachefiles_inject_read_error();
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if (xlen == 0)
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xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen);
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if (xlen != tlen) {
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if (xlen < 0)
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trace_cachefiles_vfs_error(object, file_inode(file), xlen,
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cachefiles_trace_getxattr_error);
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if (xlen == -EIO)
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cachefiles_io_error_obj(
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object,
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"Failed to read aux with error %zd", xlen);
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why = cachefiles_coherency_check_xattr;
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} else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) {
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why = cachefiles_coherency_check_type;
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} else if (memcmp(buf->data, p, len) != 0) {
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why = cachefiles_coherency_check_aux;
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} else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) {
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why = cachefiles_coherency_check_objsize;
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} else if (buf->content == CACHEFILES_CONTENT_DIRTY) {
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// TODO: Begin conflict resolution
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pr_warn("Dirty object in cache\n");
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why = cachefiles_coherency_check_dirty;
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} else {
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why = cachefiles_coherency_check_ok;
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ret = 0;
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}
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trace_cachefiles_coherency(object, file_inode(file)->i_ino,
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buf->content, why);
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kfree(buf);
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return ret;
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}
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/*
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* remove the object's xattr to mark it stale
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*/
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int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
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struct cachefiles_object *object,
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struct dentry *dentry)
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{
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int ret;
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ret = cachefiles_inject_remove_error();
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if (ret == 0)
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ret = vfs_removexattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache);
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if (ret < 0) {
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trace_cachefiles_vfs_error(object, d_inode(dentry), ret,
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cachefiles_trace_remxattr_error);
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if (ret == -ENOENT || ret == -ENODATA)
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ret = 0;
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else if (ret != -ENOMEM)
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cachefiles_io_error(cache,
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"Can't remove xattr from %lu"
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" (error %d)",
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d_backing_inode(dentry)->i_ino, -ret);
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}
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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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* Stick a marker on the cache object to indicate that it's dirty.
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*/
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void cachefiles_prepare_to_write(struct fscache_cookie *cookie)
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{
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const struct cred *saved_cred;
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struct cachefiles_object *object = cookie->cache_priv;
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struct cachefiles_cache *cache = object->volume->cache;
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_enter("c=%08x", object->cookie->debug_id);
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if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
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cachefiles_begin_secure(cache, &saved_cred);
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cachefiles_set_object_xattr(object);
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cachefiles_end_secure(cache, saved_cred);
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}
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}
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/*
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* Set the state xattr on a volume directory.
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*/
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bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
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{
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struct cachefiles_vol_xattr *buf;
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unsigned int len = volume->vcookie->coherency_len;
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const void *p = volume->vcookie->coherency;
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struct dentry *dentry = volume->dentry;
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int ret;
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_enter("%x,#%d", volume->vcookie->debug_id, len);
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len += sizeof(*buf);
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buf = kmalloc(len, GFP_KERNEL);
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if (!buf)
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return false;
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buf->reserved = cpu_to_be32(0);
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memcpy(buf->data, p, volume->vcookie->coherency_len);
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ret = cachefiles_inject_write_error();
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if (ret == 0)
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ret = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache,
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buf, len, 0);
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if (ret < 0) {
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trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret,
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cachefiles_trace_setxattr_error);
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trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
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cachefiles_coherency_vol_set_fail);
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if (ret != -ENOMEM)
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cachefiles_io_error(
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volume->cache, "Failed to set xattr with error %d", ret);
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} else {
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trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
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cachefiles_coherency_vol_set_ok);
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}
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kfree(buf);
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_leave(" = %d", ret);
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return ret == 0;
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}
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/*
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* Check the consistency between the backing cache and the volume cookie.
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*/
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int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
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{
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struct cachefiles_vol_xattr *buf;
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struct dentry *dentry = volume->dentry;
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unsigned int len = volume->vcookie->coherency_len;
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const void *p = volume->vcookie->coherency;
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enum cachefiles_coherency_trace why;
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ssize_t xlen;
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int ret = -ESTALE;
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_enter("");
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len += sizeof(*buf);
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buf = kmalloc(len, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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xlen = cachefiles_inject_read_error();
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if (xlen == 0)
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xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len);
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if (xlen != len) {
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if (xlen < 0) {
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trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
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cachefiles_trace_getxattr_error);
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if (xlen == -EIO)
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cachefiles_io_error(
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volume->cache,
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"Failed to read xattr with error %zd", xlen);
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}
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why = cachefiles_coherency_vol_check_xattr;
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} else if (buf->reserved != cpu_to_be32(0)) {
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why = cachefiles_coherency_vol_check_resv;
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} else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) {
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why = cachefiles_coherency_vol_check_cmp;
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} else {
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why = cachefiles_coherency_vol_check_ok;
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ret = 0;
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}
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trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why);
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kfree(buf);
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_leave(" = %d", ret);
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return ret;
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}
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