63 lines
1.1 KiB
C
63 lines
1.1 KiB
C
#ifndef _LINUX_BLOCKGROUP_LOCK_H
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#define _LINUX_BLOCKGROUP_LOCK_H
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/*
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* Per-blockgroup locking for ext2 and ext3.
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*
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* Simple hashed spinlocking.
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*/
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#include <linux/spinlock.h>
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#include <linux/cache.h>
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#ifdef CONFIG_SMP
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/*
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* We want a power-of-two. Is there a better way than this?
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*/
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#if NR_CPUS >= 32
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#define NR_BG_LOCKS 128
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#elif NR_CPUS >= 16
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#define NR_BG_LOCKS 64
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#elif NR_CPUS >= 8
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#define NR_BG_LOCKS 32
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#elif NR_CPUS >= 4
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#define NR_BG_LOCKS 16
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#elif NR_CPUS >= 2
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#define NR_BG_LOCKS 8
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#else
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#define NR_BG_LOCKS 4
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#endif
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#else /* CONFIG_SMP */
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#define NR_BG_LOCKS 1
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#endif /* CONFIG_SMP */
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struct bgl_lock {
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spinlock_t lock;
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} ____cacheline_aligned_in_smp;
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struct blockgroup_lock {
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struct bgl_lock locks[NR_BG_LOCKS];
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};
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static inline void bgl_lock_init(struct blockgroup_lock *bgl)
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{
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int i;
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for (i = 0; i < NR_BG_LOCKS; i++)
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spin_lock_init(&bgl->locks[i].lock);
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}
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/*
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* The accessor is a macro so we can embed a blockgroup_lock into different
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* superblock types
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*/
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static inline spinlock_t *
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bgl_lock_ptr(struct blockgroup_lock *bgl, unsigned int block_group)
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{
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return &bgl->locks[(block_group) & (NR_BG_LOCKS-1)].lock;
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}
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#endif
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