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linux/fs/btrfs/uuid-tree.c
Filipe Manana 50564b651d btrfs: abort transaction on generation mismatch when marking eb as dirty 
When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(),
we check if its generation matches the running transaction and if not we
just print a warning. Such mismatch is an indicator that something really
went wrong and only printing a warning message (and stack trace) is not
enough to prevent a corruption. Allowing a transaction to commit with such
an extent buffer will trigger an error if we ever try to read it from disk
due to a generation mismatch with its parent generation.

So abort the current transaction with -EUCLEAN if we notice a generation
mismatch. For this we need to pass a transaction handle to
btrfs_mark_buffer_dirty() which is always available except in test code,
in which case we can pass NULL since it operates on dummy extent buffers
and all test roots have a single node/leaf (root node at level 0).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12 16:44:07 +02:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) STRATO AG 2013. All rights reserved.
*/
#include <linux/uuid.h>
#include <asm/unaligned.h>
#include "messages.h"
#include "ctree.h"
#include "transaction.h"
#include "disk-io.h"
#include "print-tree.h"
#include "fs.h"
#include "accessors.h"
#include "uuid-tree.h"
static void btrfs_uuid_to_key(u8 *uuid, u8 type, struct btrfs_key *key)
{
key->type = type;
key->objectid = get_unaligned_le64(uuid);
key->offset = get_unaligned_le64(uuid + sizeof(u64));
}
/* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, u8 *uuid,
u8 type, u64 subid)
{
int ret;
struct btrfs_path *path = NULL;
struct extent_buffer *eb;
int slot;
u32 item_size;
unsigned long offset;
struct btrfs_key key;
if (WARN_ON_ONCE(!uuid_root)) {
ret = -ENOENT;
goto out;
}
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
btrfs_uuid_to_key(uuid, type, &key);
ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
if (ret < 0) {
goto out;
} else if (ret > 0) {
ret = -ENOENT;
goto out;
}
eb = path->nodes[0];
slot = path->slots[0];
item_size = btrfs_item_size(eb, slot);
offset = btrfs_item_ptr_offset(eb, slot);
ret = -ENOENT;
if (!IS_ALIGNED(item_size, sizeof(u64))) {
btrfs_warn(uuid_root->fs_info,
"uuid item with illegal size %lu!",
(unsigned long)item_size);
goto out;
}
while (item_size) {
__le64 data;
read_extent_buffer(eb, &data, offset, sizeof(data));
if (le64_to_cpu(data) == subid) {
ret = 0;
break;
}
offset += sizeof(data);
item_size -= sizeof(data);
}
out:
btrfs_free_path(path);
return ret;
}
int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
u64 subid_cpu)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *uuid_root = fs_info->uuid_root;
int ret;
struct btrfs_path *path = NULL;
struct btrfs_key key;
struct extent_buffer *eb;
int slot;
unsigned long offset;
__le64 subid_le;
ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
if (ret != -ENOENT)
return ret;
if (WARN_ON_ONCE(!uuid_root)) {
ret = -EINVAL;
goto out;
}
btrfs_uuid_to_key(uuid, type, &key);
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
sizeof(subid_le));
if (ret >= 0) {
/* Add an item for the type for the first time */
eb = path->nodes[0];
slot = path->slots[0];
offset = btrfs_item_ptr_offset(eb, slot);
} else if (ret == -EEXIST) {
/*
* An item with that type already exists.
* Extend the item and store the new subid at the end.
*/
btrfs_extend_item(trans, path, sizeof(subid_le));
eb = path->nodes[0];
slot = path->slots[0];
offset = btrfs_item_ptr_offset(eb, slot);
offset += btrfs_item_size(eb, slot) - sizeof(subid_le);
} else {
btrfs_warn(fs_info,
"insert uuid item failed %d (0x%016llx, 0x%016llx) type %u!",
ret, key.objectid, key.offset, type);
goto out;
}
ret = 0;
subid_le = cpu_to_le64(subid_cpu);
write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
btrfs_mark_buffer_dirty(trans, eb);
out:
btrfs_free_path(path);
return ret;
}
int btrfs_uuid_tree_remove(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
u64 subid)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *uuid_root = fs_info->uuid_root;
int ret;
struct btrfs_path *path = NULL;
struct btrfs_key key;
struct extent_buffer *eb;
int slot;
unsigned long offset;
u32 item_size;
unsigned long move_dst;
unsigned long move_src;
unsigned long move_len;
if (WARN_ON_ONCE(!uuid_root)) {
ret = -EINVAL;
goto out;
}
btrfs_uuid_to_key(uuid, type, &key);
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
if (ret < 0) {
btrfs_warn(fs_info, "error %d while searching for uuid item!",
ret);
goto out;
}
if (ret > 0) {
ret = -ENOENT;
goto out;
}
eb = path->nodes[0];
slot = path->slots[0];
offset = btrfs_item_ptr_offset(eb, slot);
item_size = btrfs_item_size(eb, slot);
if (!IS_ALIGNED(item_size, sizeof(u64))) {
btrfs_warn(fs_info, "uuid item with illegal size %lu!",
(unsigned long)item_size);
ret = -ENOENT;
goto out;
}
while (item_size) {
__le64 read_subid;
read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
if (le64_to_cpu(read_subid) == subid)
break;
offset += sizeof(read_subid);
item_size -= sizeof(read_subid);
}
if (!item_size) {
ret = -ENOENT;
goto out;
}
item_size = btrfs_item_size(eb, slot);
if (item_size == sizeof(subid)) {
ret = btrfs_del_item(trans, uuid_root, path);
goto out;
}
move_dst = offset;
move_src = offset + sizeof(subid);
move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
memmove_extent_buffer(eb, move_dst, move_src, move_len);
btrfs_truncate_item(trans, path, item_size - sizeof(subid), 1);
out:
btrfs_free_path(path);
return ret;
}
static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
u64 subid)
{
struct btrfs_trans_handle *trans;
int ret;
/* 1 - for the uuid item */
trans = btrfs_start_transaction(uuid_root, 1);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
goto out;
}
ret = btrfs_uuid_tree_remove(trans, uuid, type, subid);
btrfs_end_transaction(trans);
out:
return ret;
}
/*
* Check if there's an matching subvolume for given UUID
*
* Return:
* 0 check succeeded, the entry is not outdated
* > 0 if the check failed, the caller should remove the entry
* < 0 if an error occurred
*/
static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
u8 *uuid, u8 type, u64 subvolid)
{
int ret = 0;
struct btrfs_root *subvol_root;
if (type != BTRFS_UUID_KEY_SUBVOL &&
type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
goto out;
subvol_root = btrfs_get_fs_root(fs_info, subvolid, true);
if (IS_ERR(subvol_root)) {
ret = PTR_ERR(subvol_root);
if (ret == -ENOENT)
ret = 1;
goto out;
}
switch (type) {
case BTRFS_UUID_KEY_SUBVOL:
if (memcmp(uuid, subvol_root->root_item.uuid, BTRFS_UUID_SIZE))
ret = 1;
break;
case BTRFS_UUID_KEY_RECEIVED_SUBVOL:
if (memcmp(uuid, subvol_root->root_item.received_uuid,
BTRFS_UUID_SIZE))
ret = 1;
break;
}
btrfs_put_root(subvol_root);
out:
return ret;
}
int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info)
{
struct btrfs_root *root = fs_info->uuid_root;
struct btrfs_key key;
struct btrfs_path *path;
int ret = 0;
struct extent_buffer *leaf;
int slot;
u32 item_size;
unsigned long offset;
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
key.objectid = 0;
key.type = 0;
key.offset = 0;
again_search_slot:
ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION);
if (ret) {
if (ret > 0)
ret = 0;
goto out;
}
while (1) {
if (btrfs_fs_closing(fs_info)) {
ret = -EINTR;
goto out;
}
cond_resched();
leaf = path->nodes[0];
slot = path->slots[0];
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.type != BTRFS_UUID_KEY_SUBVOL &&
key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
goto skip;
offset = btrfs_item_ptr_offset(leaf, slot);
item_size = btrfs_item_size(leaf, slot);
if (!IS_ALIGNED(item_size, sizeof(u64))) {
btrfs_warn(fs_info,
"uuid item with illegal size %lu!",
(unsigned long)item_size);
goto skip;
}
while (item_size) {
u8 uuid[BTRFS_UUID_SIZE];
__le64 subid_le;
u64 subid_cpu;
put_unaligned_le64(key.objectid, uuid);
put_unaligned_le64(key.offset, uuid + sizeof(u64));
read_extent_buffer(leaf, &subid_le, offset,
sizeof(subid_le));
subid_cpu = le64_to_cpu(subid_le);
ret = btrfs_check_uuid_tree_entry(fs_info, uuid,
key.type, subid_cpu);
if (ret < 0)
goto out;
if (ret > 0) {
btrfs_release_path(path);
ret = btrfs_uuid_iter_rem(root, uuid, key.type,
subid_cpu);
if (ret == 0) {
/*
* this might look inefficient, but the
* justification is that it is an
* exception that check_func returns 1,
* and that in the regular case only one
* entry per UUID exists.
*/
goto again_search_slot;
}
if (ret < 0 && ret != -ENOENT)
goto out;
key.offset++;
goto again_search_slot;
}
item_size -= sizeof(subid_le);
offset += sizeof(subid_le);
}
skip:
ret = btrfs_next_item(root, path);
if (ret == 0)
continue;
else if (ret > 0)
ret = 0;
break;
}
out:
btrfs_free_path(path);
return ret;
}
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