7c5f6b320b
We can use ilog2() to more easily produce the desired NR_BG_LOCKS. This works because ilog2() is evaluated at compile-time when its argument is a compile-time constant. I did not change the chosen NR_BG_LOCKS values. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Andreas Dilger <adilger@dilger.ca>
41 lines
771 B
C
41 lines
771 B
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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#define NR_BG_LOCKS (4 << ilog2(NR_CPUS < 32 ? NR_CPUS : 32))
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#else
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#define NR_BG_LOCKS 1
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#endif
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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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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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