linux/fs/btrfs/props.c
Omar Sandoval caae78e032 btrfs: move common inode creation code into btrfs_create_new_inode()
All of our inode creation code paths duplicate the calls to
btrfs_init_inode_security() and btrfs_add_link(). Subvolume creation
additionally duplicates property inheritance and the call to
btrfs_set_inode_index(). Fix this by moving the common code into
btrfs_create_new_inode(). This accomplishes a few things at once:

1. It reduces code duplication.

2. It allows us to set up the inode completely before inserting the
   inode item, removing calls to btrfs_update_inode().

3. It fixes a leak of an inode on disk in some error cases. For example,
   in btrfs_create(), if btrfs_new_inode() succeeds, then we have
   inserted an inode item and its inode ref. However, if something after
   that fails (e.g., btrfs_init_inode_security()), then we end the
   transaction and then decrement the link count on the inode. If the
   transaction is committed and the system crashes before the failed
   inode is deleted, then we leak that inode on disk. Instead, this
   refactoring aborts the transaction when we can't recover more
   gracefully.

4. It exposes various ways that subvolume creation diverges from mkdir
   in terms of inheriting flags, properties, permissions, and POSIX
   ACLs, a lot of which appears to be accidental. This patch explicitly
   does _not_ change the existing non-standard behavior, but it makes
   those differences more clear in the code and documents them so that
   we can discuss whether they should be changed.

Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2022-05-16 17:03:08 +02:00

471 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2014 Filipe David Borba Manana <fdmanana@gmail.com>
*/
#include <linux/hashtable.h>
#include "props.h"
#include "btrfs_inode.h"
#include "transaction.h"
#include "ctree.h"
#include "xattr.h"
#include "compression.h"
#define BTRFS_PROP_HANDLERS_HT_BITS 8
static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
struct prop_handler {
struct hlist_node node;
const char *xattr_name;
int (*validate)(const struct btrfs_inode *inode, const char *value,
size_t len);
int (*apply)(struct inode *inode, const char *value, size_t len);
const char *(*extract)(struct inode *inode);
bool (*ignore)(const struct btrfs_inode *inode);
int inheritable;
};
static const struct hlist_head *find_prop_handlers_by_hash(const u64 hash)
{
struct hlist_head *h;
h = &prop_handlers_ht[hash_min(hash, BTRFS_PROP_HANDLERS_HT_BITS)];
if (hlist_empty(h))
return NULL;
return h;
}
static const struct prop_handler *
find_prop_handler(const char *name,
const struct hlist_head *handlers)
{
struct prop_handler *h;
if (!handlers) {
u64 hash = btrfs_name_hash(name, strlen(name));
handlers = find_prop_handlers_by_hash(hash);
if (!handlers)
return NULL;
}
hlist_for_each_entry(h, handlers, node)
if (!strcmp(h->xattr_name, name))
return h;
return NULL;
}
int btrfs_validate_prop(const struct btrfs_inode *inode, const char *name,
const char *value, size_t value_len)
{
const struct prop_handler *handler;
if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
return -EINVAL;
handler = find_prop_handler(name, NULL);
if (!handler)
return -EINVAL;
if (value_len == 0)
return 0;
return handler->validate(inode, value, value_len);
}
/*
* Check if a property should be ignored (not set) for an inode.
*
* @inode: The target inode.
* @name: The property's name.
*
* The caller must be sure the given property name is valid, for example by
* having previously called btrfs_validate_prop().
*
* Returns: true if the property should be ignored for the given inode
* false if the property must not be ignored for the given inode
*/
bool btrfs_ignore_prop(const struct btrfs_inode *inode, const char *name)
{
const struct prop_handler *handler;
handler = find_prop_handler(name, NULL);
ASSERT(handler != NULL);
return handler->ignore(inode);
}
int btrfs_set_prop(struct btrfs_trans_handle *trans, struct inode *inode,
const char *name, const char *value, size_t value_len,
int flags)
{
const struct prop_handler *handler;
int ret;
handler = find_prop_handler(name, NULL);
if (!handler)
return -EINVAL;
if (value_len == 0) {
ret = btrfs_setxattr(trans, inode, handler->xattr_name,
NULL, 0, flags);
if (ret)
return ret;
ret = handler->apply(inode, NULL, 0);
ASSERT(ret == 0);
return ret;
}
ret = btrfs_setxattr(trans, inode, handler->xattr_name, value,
value_len, flags);
if (ret)
return ret;
ret = handler->apply(inode, value, value_len);
if (ret) {
btrfs_setxattr(trans, inode, handler->xattr_name, NULL,
0, flags);
return ret;
}
set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
return 0;
}
static int iterate_object_props(struct btrfs_root *root,
struct btrfs_path *path,
u64 objectid,
void (*iterator)(void *,
const struct prop_handler *,
const char *,
size_t),
void *ctx)
{
int ret;
char *name_buf = NULL;
char *value_buf = NULL;
int name_buf_len = 0;
int value_buf_len = 0;
while (1) {
struct btrfs_key key;
struct btrfs_dir_item *di;
struct extent_buffer *leaf;
u32 total_len, cur, this_len;
int slot;
const struct hlist_head *handlers;
slot = path->slots[0];
leaf = path->nodes[0];
if (slot >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(root, path);
if (ret < 0)
goto out;
else if (ret > 0)
break;
continue;
}
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != objectid)
break;
if (key.type != BTRFS_XATTR_ITEM_KEY)
break;
handlers = find_prop_handlers_by_hash(key.offset);
if (!handlers)
goto next_slot;
di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
cur = 0;
total_len = btrfs_item_size(leaf, slot);
while (cur < total_len) {
u32 name_len = btrfs_dir_name_len(leaf, di);
u32 data_len = btrfs_dir_data_len(leaf, di);
unsigned long name_ptr, data_ptr;
const struct prop_handler *handler;
this_len = sizeof(*di) + name_len + data_len;
name_ptr = (unsigned long)(di + 1);
data_ptr = name_ptr + name_len;
if (name_len <= XATTR_BTRFS_PREFIX_LEN ||
memcmp_extent_buffer(leaf, XATTR_BTRFS_PREFIX,
name_ptr,
XATTR_BTRFS_PREFIX_LEN))
goto next_dir_item;
if (name_len >= name_buf_len) {
kfree(name_buf);
name_buf_len = name_len + 1;
name_buf = kmalloc(name_buf_len, GFP_NOFS);
if (!name_buf) {
ret = -ENOMEM;
goto out;
}
}
read_extent_buffer(leaf, name_buf, name_ptr, name_len);
name_buf[name_len] = '\0';
handler = find_prop_handler(name_buf, handlers);
if (!handler)
goto next_dir_item;
if (data_len > value_buf_len) {
kfree(value_buf);
value_buf_len = data_len;
value_buf = kmalloc(data_len, GFP_NOFS);
if (!value_buf) {
ret = -ENOMEM;
goto out;
}
}
read_extent_buffer(leaf, value_buf, data_ptr, data_len);
iterator(ctx, handler, value_buf, data_len);
next_dir_item:
cur += this_len;
di = (struct btrfs_dir_item *)((char *) di + this_len);
}
next_slot:
path->slots[0]++;
}
ret = 0;
out:
btrfs_release_path(path);
kfree(name_buf);
kfree(value_buf);
return ret;
}
static void inode_prop_iterator(void *ctx,
const struct prop_handler *handler,
const char *value,
size_t len)
{
struct inode *inode = ctx;
struct btrfs_root *root = BTRFS_I(inode)->root;
int ret;
ret = handler->apply(inode, value, len);
if (unlikely(ret))
btrfs_warn(root->fs_info,
"error applying prop %s to ino %llu (root %llu): %d",
handler->xattr_name, btrfs_ino(BTRFS_I(inode)),
root->root_key.objectid, ret);
else
set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
}
int btrfs_load_inode_props(struct inode *inode, struct btrfs_path *path)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
u64 ino = btrfs_ino(BTRFS_I(inode));
int ret;
ret = iterate_object_props(root, path, ino, inode_prop_iterator, inode);
return ret;
}
static int prop_compression_validate(const struct btrfs_inode *inode,
const char *value, size_t len)
{
if (!btrfs_inode_can_compress(inode))
return -EINVAL;
if (!value)
return 0;
if (btrfs_compress_is_valid_type(value, len))
return 0;
if ((len == 2 && strncmp("no", value, 2) == 0) ||
(len == 4 && strncmp("none", value, 4) == 0))
return 0;
return -EINVAL;
}
static int prop_compression_apply(struct inode *inode, const char *value,
size_t len)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
int type;
/* Reset to defaults */
if (len == 0) {
BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
BTRFS_I(inode)->prop_compress = BTRFS_COMPRESS_NONE;
return 0;
}
/* Set NOCOMPRESS flag */
if ((len == 2 && strncmp("no", value, 2) == 0) ||
(len == 4 && strncmp("none", value, 4) == 0)) {
BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
BTRFS_I(inode)->prop_compress = BTRFS_COMPRESS_NONE;
return 0;
}
if (!strncmp("lzo", value, 3)) {
type = BTRFS_COMPRESS_LZO;
btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
} else if (!strncmp("zlib", value, 4)) {
type = BTRFS_COMPRESS_ZLIB;
} else if (!strncmp("zstd", value, 4)) {
type = BTRFS_COMPRESS_ZSTD;
btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
} else {
return -EINVAL;
}
BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
BTRFS_I(inode)->prop_compress = type;
return 0;
}
static bool prop_compression_ignore(const struct btrfs_inode *inode)
{
/*
* Compression only has effect for regular files, and for directories
* we set it just to propagate it to new files created inside them.
* Everything else (symlinks, devices, sockets, fifos) is pointless as
* it will do nothing, so don't waste metadata space on a compression
* xattr for anything that is neither a file nor a directory.
*/
if (!S_ISREG(inode->vfs_inode.i_mode) &&
!S_ISDIR(inode->vfs_inode.i_mode))
return true;
return false;
}
static const char *prop_compression_extract(struct inode *inode)
{
switch (BTRFS_I(inode)->prop_compress) {
case BTRFS_COMPRESS_ZLIB:
case BTRFS_COMPRESS_LZO:
case BTRFS_COMPRESS_ZSTD:
return btrfs_compress_type2str(BTRFS_I(inode)->prop_compress);
default:
break;
}
return NULL;
}
static struct prop_handler prop_handlers[] = {
{
.xattr_name = XATTR_BTRFS_PREFIX "compression",
.validate = prop_compression_validate,
.apply = prop_compression_apply,
.extract = prop_compression_extract,
.ignore = prop_compression_ignore,
.inheritable = 1
},
};
int btrfs_inode_inherit_props(struct btrfs_trans_handle *trans,
struct inode *inode, struct inode *parent)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_fs_info *fs_info = root->fs_info;
int ret;
int i;
bool need_reserve = false;
if (!test_bit(BTRFS_INODE_HAS_PROPS,
&BTRFS_I(parent)->runtime_flags))
return 0;
for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
const struct prop_handler *h = &prop_handlers[i];
const char *value;
u64 num_bytes = 0;
if (!h->inheritable)
continue;
if (h->ignore(BTRFS_I(inode)))
continue;
value = h->extract(parent);
if (!value)
continue;
/*
* This is not strictly necessary as the property should be
* valid, but in case it isn't, don't propagate it further.
*/
ret = h->validate(BTRFS_I(inode), value, strlen(value));
if (ret)
continue;
/*
* Currently callers should be reserving 1 item for properties,
* since we only have 1 property that we currently support. If
* we add more in the future we need to try and reserve more
* space for them. But we should also revisit how we do space
* reservations if we do add more properties in the future.
*/
if (need_reserve) {
num_bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
ret = btrfs_block_rsv_add(fs_info, trans->block_rsv,
num_bytes,
BTRFS_RESERVE_NO_FLUSH);
if (ret)
return ret;
}
ret = btrfs_setxattr(trans, inode, h->xattr_name, value,
strlen(value), 0);
if (!ret) {
ret = h->apply(inode, value, strlen(value));
if (ret)
btrfs_setxattr(trans, inode, h->xattr_name,
NULL, 0, 0);
else
set_bit(BTRFS_INODE_HAS_PROPS,
&BTRFS_I(inode)->runtime_flags);
}
if (need_reserve) {
btrfs_block_rsv_release(fs_info, trans->block_rsv,
num_bytes, NULL);
if (ret)
return ret;
}
need_reserve = true;
}
return 0;
}
void __init btrfs_props_init(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
struct prop_handler *p = &prop_handlers[i];
u64 h = btrfs_name_hash(p->xattr_name, strlen(p->xattr_name));
hash_add(prop_handlers_ht, &p->node, h);
}
}