mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-17 09:43:59 +08:00
49d0c6424c
We currently use lockdep_assert_held() at btrfs_assert_tree_locked(), and that checks that we hold a lock either in read mode or write mode. However in all contexts we use btrfs_assert_tree_locked(), we actually want to check if we are holding a write lock on the extent buffer's rw semaphore - it would be a bug if in any of those contexts we were holding a read lock instead. So change btrfs_assert_tree_locked() to use lockdep_assert_held_write() instead and, to make it more explicit, rename btrfs_assert_tree_locked() to btrfs_assert_tree_write_locked(), so that it's clear we want to check we are holding a write lock. For now there are no contexts where we want to assert that we must have a read lock, but in case that is needed in the future, we can add a new helper function that just calls out lockdep_assert_held_read(). Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
135 lines
4.3 KiB
C
135 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* Copyright (C) 2008 Oracle. All rights reserved.
|
|
*/
|
|
|
|
#ifndef BTRFS_LOCKING_H
|
|
#define BTRFS_LOCKING_H
|
|
|
|
#include <linux/atomic.h>
|
|
#include <linux/wait.h>
|
|
#include <linux/percpu_counter.h>
|
|
#include "extent_io.h"
|
|
|
|
#define BTRFS_WRITE_LOCK 1
|
|
#define BTRFS_READ_LOCK 2
|
|
|
|
/*
|
|
* We are limited in number of subclasses by MAX_LOCKDEP_SUBCLASSES, which at
|
|
* the time of this patch is 8, which is how many we use. Keep this in mind if
|
|
* you decide you want to add another subclass.
|
|
*/
|
|
enum btrfs_lock_nesting {
|
|
BTRFS_NESTING_NORMAL,
|
|
|
|
/*
|
|
* When we COW a block we are holding the lock on the original block,
|
|
* and since our lockdep maps are rootid+level, this confuses lockdep
|
|
* when we lock the newly allocated COW'd block. Handle this by having
|
|
* a subclass for COW'ed blocks so that lockdep doesn't complain.
|
|
*/
|
|
BTRFS_NESTING_COW,
|
|
|
|
/*
|
|
* Oftentimes we need to lock adjacent nodes on the same level while
|
|
* still holding the lock on the original node we searched to, such as
|
|
* for searching forward or for split/balance.
|
|
*
|
|
* Because of this we need to indicate to lockdep that this is
|
|
* acceptable by having a different subclass for each of these
|
|
* operations.
|
|
*/
|
|
BTRFS_NESTING_LEFT,
|
|
BTRFS_NESTING_RIGHT,
|
|
|
|
/*
|
|
* When splitting we will be holding a lock on the left/right node when
|
|
* we need to cow that node, thus we need a new set of subclasses for
|
|
* these two operations.
|
|
*/
|
|
BTRFS_NESTING_LEFT_COW,
|
|
BTRFS_NESTING_RIGHT_COW,
|
|
|
|
/*
|
|
* When splitting we may push nodes to the left or right, but still use
|
|
* the subsequent nodes in our path, keeping our locks on those adjacent
|
|
* blocks. Thus when we go to allocate a new split block we've already
|
|
* used up all of our available subclasses, so this subclass exists to
|
|
* handle this case where we need to allocate a new split block.
|
|
*/
|
|
BTRFS_NESTING_SPLIT,
|
|
|
|
/*
|
|
* When promoting a new block to a root we need to have a special
|
|
* subclass so we don't confuse lockdep, as it will appear that we are
|
|
* locking a higher level node before a lower level one. Copying also
|
|
* has this problem as it appears we're locking the same block again
|
|
* when we make a snapshot of an existing root.
|
|
*/
|
|
BTRFS_NESTING_NEW_ROOT,
|
|
|
|
/*
|
|
* We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so
|
|
* add this in here and add a static_assert to keep us from going over
|
|
* the limit. As of this writing we're limited to 8, and we're
|
|
* definitely using 8, hence this check to keep us from messing up in
|
|
* the future.
|
|
*/
|
|
BTRFS_NESTING_MAX,
|
|
};
|
|
|
|
static_assert(BTRFS_NESTING_MAX <= MAX_LOCKDEP_SUBCLASSES,
|
|
"too many lock subclasses defined");
|
|
|
|
struct btrfs_path;
|
|
|
|
void __btrfs_tree_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest);
|
|
void btrfs_tree_lock(struct extent_buffer *eb);
|
|
void btrfs_tree_unlock(struct extent_buffer *eb);
|
|
|
|
void __btrfs_tree_read_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest);
|
|
void btrfs_tree_read_lock(struct extent_buffer *eb);
|
|
void btrfs_tree_read_unlock(struct extent_buffer *eb);
|
|
int btrfs_try_tree_read_lock(struct extent_buffer *eb);
|
|
int btrfs_try_tree_write_lock(struct extent_buffer *eb);
|
|
struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
|
|
struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root);
|
|
|
|
#ifdef CONFIG_BTRFS_DEBUG
|
|
static inline void btrfs_assert_tree_write_locked(struct extent_buffer *eb)
|
|
{
|
|
lockdep_assert_held_write(&eb->lock);
|
|
}
|
|
#else
|
|
static inline void btrfs_assert_tree_write_locked(struct extent_buffer *eb) { }
|
|
#endif
|
|
|
|
void btrfs_unlock_up_safe(struct btrfs_path *path, int level);
|
|
|
|
static inline void btrfs_tree_unlock_rw(struct extent_buffer *eb, int rw)
|
|
{
|
|
if (rw == BTRFS_WRITE_LOCK)
|
|
btrfs_tree_unlock(eb);
|
|
else if (rw == BTRFS_READ_LOCK)
|
|
btrfs_tree_read_unlock(eb);
|
|
else
|
|
BUG();
|
|
}
|
|
|
|
struct btrfs_drew_lock {
|
|
atomic_t readers;
|
|
struct percpu_counter writers;
|
|
wait_queue_head_t pending_writers;
|
|
wait_queue_head_t pending_readers;
|
|
};
|
|
|
|
int btrfs_drew_lock_init(struct btrfs_drew_lock *lock);
|
|
void btrfs_drew_lock_destroy(struct btrfs_drew_lock *lock);
|
|
void btrfs_drew_write_lock(struct btrfs_drew_lock *lock);
|
|
bool btrfs_drew_try_write_lock(struct btrfs_drew_lock *lock);
|
|
void btrfs_drew_write_unlock(struct btrfs_drew_lock *lock);
|
|
void btrfs_drew_read_lock(struct btrfs_drew_lock *lock);
|
|
void btrfs_drew_read_unlock(struct btrfs_drew_lock *lock);
|
|
|
|
#endif
|