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https://gitee.com/bianbu-linux/linux-6.6
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51899412dd
Our current tree locking stuff allows us to recurse with read locks if we're already holding the write lock. This is necessary for the space cache inode, as we could be holding a lock on the root_tree root when we need to cache a block group, and thus need to be able to read down the root_tree to read in the inode cache. We can get away with this in our current locking, but we won't be able to with a rwsem. Handle this by purposefully annotating the places where we require recursion, so that in the future we can maybe come up with a way to avoid the recursion. In the case of the free space inode, this will be superseded by the free space tree. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
80 lines
2.5 KiB
C
80 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*/
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#ifndef BTRFS_LOCKING_H
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#define BTRFS_LOCKING_H
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#include <linux/atomic.h>
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#include <linux/wait.h>
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#include <linux/percpu_counter.h>
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#include "extent_io.h"
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#define BTRFS_WRITE_LOCK 1
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#define BTRFS_READ_LOCK 2
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#define BTRFS_WRITE_LOCK_BLOCKING 3
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#define BTRFS_READ_LOCK_BLOCKING 4
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struct btrfs_path;
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void btrfs_tree_lock(struct extent_buffer *eb);
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void btrfs_tree_unlock(struct extent_buffer *eb);
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void __btrfs_tree_read_lock(struct extent_buffer *eb, bool recurse);
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void btrfs_tree_read_lock(struct extent_buffer *eb);
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void btrfs_tree_read_unlock(struct extent_buffer *eb);
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void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb);
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void btrfs_set_lock_blocking_read(struct extent_buffer *eb);
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void btrfs_set_lock_blocking_write(struct extent_buffer *eb);
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int btrfs_try_tree_read_lock(struct extent_buffer *eb);
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int btrfs_try_tree_write_lock(struct extent_buffer *eb);
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int btrfs_tree_read_lock_atomic(struct extent_buffer *eb);
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struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
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struct extent_buffer *__btrfs_read_lock_root_node(struct btrfs_root *root,
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bool recurse);
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static inline struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
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{
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return __btrfs_read_lock_root_node(root, false);
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}
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#ifdef CONFIG_BTRFS_DEBUG
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static inline void btrfs_assert_tree_locked(struct extent_buffer *eb) {
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BUG_ON(!eb->write_locks);
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}
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#else
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static inline void btrfs_assert_tree_locked(struct extent_buffer *eb) { }
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#endif
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void btrfs_set_path_blocking(struct btrfs_path *p);
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void btrfs_unlock_up_safe(struct btrfs_path *path, int level);
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static inline void btrfs_tree_unlock_rw(struct extent_buffer *eb, int rw)
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{
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if (rw == BTRFS_WRITE_LOCK || rw == BTRFS_WRITE_LOCK_BLOCKING)
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btrfs_tree_unlock(eb);
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else if (rw == BTRFS_READ_LOCK_BLOCKING)
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btrfs_tree_read_unlock_blocking(eb);
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else if (rw == BTRFS_READ_LOCK)
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btrfs_tree_read_unlock(eb);
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else
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BUG();
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}
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struct btrfs_drew_lock {
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atomic_t readers;
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struct percpu_counter writers;
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wait_queue_head_t pending_writers;
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wait_queue_head_t pending_readers;
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};
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int btrfs_drew_lock_init(struct btrfs_drew_lock *lock);
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void btrfs_drew_lock_destroy(struct btrfs_drew_lock *lock);
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void btrfs_drew_write_lock(struct btrfs_drew_lock *lock);
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bool btrfs_drew_try_write_lock(struct btrfs_drew_lock *lock);
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void btrfs_drew_write_unlock(struct btrfs_drew_lock *lock);
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void btrfs_drew_read_lock(struct btrfs_drew_lock *lock);
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void btrfs_drew_read_unlock(struct btrfs_drew_lock *lock);
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#endif
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