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a7ecd30c83
We have a unique lock used for controlling adding to the pagecache: the lock has two states, where both states are shared - the lock may be held multiple times for either state - but not both states at the same time. This is exactly what we need for nocow mode locking, so this patch pulls it out of fs.c into its own file. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
28 lines
743 B
C
28 lines
743 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BCACHEFS_TWO_STATE_LOCK_H
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#define _BCACHEFS_TWO_STATE_LOCK_H
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#include <linux/atomic.h>
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#include <linux/sched.h>
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#include <linux/wait.h>
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/*
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* Two-state lock - can be taken for add or block - both states are shared,
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* like read side of rwsem, but conflict with other state:
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*/
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typedef struct {
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atomic_long_t v;
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wait_queue_head_t wait;
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} two_state_lock_t;
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static inline void two_state_lock_init(two_state_lock_t *lock)
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{
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atomic_long_set(&lock->v, 0);
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init_waitqueue_head(&lock->wait);
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}
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void bch2_two_state_unlock(two_state_lock_t *, int);
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bool bch2_two_state_trylock(two_state_lock_t *, int);
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void bch2_two_state_lock(two_state_lock_t *, int);
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#endif /* _BCACHEFS_TWO_STATE_LOCK_H */
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