hi all
the codes about filesystem in the kernel is:
static inline struct list_head * d_hash(struct dentry *parent,
unsigned long hash){
hash += (unsigned long)parent / L1_CACHE_BYTES;
hash = hash^(hash>>D_HASHBITS)^(hash>>D_HASHBITS*2);
return dentry_hashtable + (hash & D_HASHMASK);}
I know the function parameter of hash belongs to the qstr string is looking
up, and the local variableshash should add the *address of the dentry of
parent*.
Why count the hash value use "L1_CACHE_BYTES" , "D_HASHBITS" and
"D_HASHMASK"?
And How to understand the codes following ?
hash += (unsigned long)parent / L1_CACHE_BYTES;
hash = hash^(hash>>D_HASHBITS)^(hash>>D_HASHBITS*2);
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