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jbd2: use a better hash function for the revoke table
The old hash function didn't work well for 64-bit block numbers, and used undefined (negative) shift right behavior. Use the generic 64-bit hash function instead. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reported-by: Andrey Ryabinin <a.ryabinin@samsung.com>
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@ -92,6 +92,7 @@
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#include <linux/init.h>
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#include <linux/bio.h>
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#include <linux/log2.h>
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#include <linux/hash.h>
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#endif
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static struct kmem_cache *jbd2_revoke_record_cache;
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@ -130,16 +131,9 @@ static void flush_descriptor(journal_t *, struct buffer_head *, int, int);
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/* Utility functions to maintain the revoke table */
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/* Borrowed from buffer.c: this is a tried and tested block hash function */
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static inline int hash(journal_t *journal, unsigned long long block)
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{
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struct jbd2_revoke_table_s *table = journal->j_revoke;
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int hash_shift = table->hash_shift;
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int hash = (int)block ^ (int)((block >> 31) >> 1);
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return ((hash << (hash_shift - 6)) ^
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(hash >> 13) ^
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(hash << (hash_shift - 12))) & (table->hash_size - 1);
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return hash_64(block, journal->j_revoke->hash_shift);
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}
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static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
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