mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-16 01:04:08 +08:00
f82c458a2c
The fair reader/writer locks mean that btrfs_clear_path_blocking needs to strictly follow lock ordering rules even when we already have blocking locks on a given path. Before we can clear a blocking lock on the path, we need to make sure all of the locks have been converted to blocking. This will remove lock inversions against anyone spinning in write_lock() against the buffers we're trying to get read locks on. These inversions didn't exist before the fair read/writer locks, but now we need to be more careful. We papered over this deadlock in the past by changing btrfs_try_read_lock() to be a true trylock against both the spinlock and the blocking lock. This was slower, and not sufficient to fix all the deadlocks. This patch adds a btrfs_tree_read_lock_atomic(), which basically means get the spinlock but trylock on the blocking lock. Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Josef Bacik <jbacik@fb.com> Reported-by: Patrick Schmid <schmid@phys.ethz.ch> cc: stable@vger.kernel.org #v3.15+
63 lines
2.1 KiB
C
63 lines
2.1 KiB
C
/*
|
|
* Copyright (C) 2008 Oracle. All rights reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public
|
|
* License v2 as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public
|
|
* License along with this program; if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
* Boston, MA 021110-1307, USA.
|
|
*/
|
|
|
|
#ifndef __BTRFS_LOCKING_
|
|
#define __BTRFS_LOCKING_
|
|
|
|
#define BTRFS_WRITE_LOCK 1
|
|
#define BTRFS_READ_LOCK 2
|
|
#define BTRFS_WRITE_LOCK_BLOCKING 3
|
|
#define BTRFS_READ_LOCK_BLOCKING 4
|
|
|
|
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);
|
|
void btrfs_tree_read_unlock(struct extent_buffer *eb);
|
|
void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb);
|
|
void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw);
|
|
void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw);
|
|
void btrfs_assert_tree_locked(struct extent_buffer *eb);
|
|
int btrfs_try_tree_read_lock(struct extent_buffer *eb);
|
|
int btrfs_try_tree_write_lock(struct extent_buffer *eb);
|
|
int btrfs_tree_read_lock_atomic(struct extent_buffer *eb);
|
|
|
|
|
|
static inline void btrfs_tree_unlock_rw(struct extent_buffer *eb, int rw)
|
|
{
|
|
if (rw == BTRFS_WRITE_LOCK || rw == BTRFS_WRITE_LOCK_BLOCKING)
|
|
btrfs_tree_unlock(eb);
|
|
else if (rw == BTRFS_READ_LOCK_BLOCKING)
|
|
btrfs_tree_read_unlock_blocking(eb);
|
|
else if (rw == BTRFS_READ_LOCK)
|
|
btrfs_tree_read_unlock(eb);
|
|
else
|
|
BUG();
|
|
}
|
|
|
|
static inline void btrfs_set_lock_blocking(struct extent_buffer *eb)
|
|
{
|
|
btrfs_set_lock_blocking_rw(eb, BTRFS_WRITE_LOCK);
|
|
}
|
|
|
|
static inline void btrfs_clear_lock_blocking(struct extent_buffer *eb)
|
|
{
|
|
btrfs_clear_lock_blocking_rw(eb, BTRFS_WRITE_LOCK_BLOCKING);
|
|
}
|
|
#endif
|