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Bug#28478 - Improper key_cache_block_size corrupts MyISAM tables

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Setting a key_cache_block_size which is not a power of 2
could corrupt MyISAM tables.

A couple of computations in the key cache code use bit
operations which do only work if key_cache_block_size
is a power of 2.

Replaced bit operations by arithmetic operations
to make key cache able to handle block sizes that are
not a power of 2.


include/keycache.h:
  Bug#28478 - Improper key_cache_block_size corrupts MyISAM tables
  Removed element 'key_cache_shift' from KEY_CACHE after
  the changes in mf_keycache.c made it unused.
mysql-test/r/key_cache.result:
  Bug#28478 - Improper key_cache_block_size corrupts MyISAM tables
  Added test result
mysql-test/t/key_cache.test:
  Bug#28478 - Improper key_cache_block_size corrupts MyISAM tables
  Added test
mysys/mf_keycache.c:
  Bug#28478 - Improper key_cache_block_size corrupts MyISAM tables
  Replaced bit operations by arithmetic operations
  to make key cache able to handle block sizes that are
  not a power of 2.
This commit is contained in:
unknown 2007-05-31 20:04:54 +02:00
parent b9ec849bb2
commit 489a3fe4ee
4 changed files with 59 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
include/keycache.h
View file

@ -46,7 +46,6 @@ typedef struct st_key_cache
my_bool key_cache_inited;
my_bool resize_in_flush; /* true during flush of resize operation */
my_bool can_be_used; /* usage of cache for read/write is allowed */
uint key_cache_shift;
ulong key_cache_mem_size; /* specified size of the cache memory */
uint key_cache_block_size; /* size of the page buffer of a cache block */
ulong min_warm_blocks; /* min number of warm blocks; */

27
mysql-test/r/key_cache.result
View file

@ -341,3 +341,30 @@ Warning 1438 Cannot drop default keycache
select @@global.key_buffer_size;
@@global.key_buffer_size
2097152
SET @bug28478_key_cache_block_size= @@global.key_cache_block_size;
SET GLOBAL key_cache_block_size= 1536;
CREATE TABLE t1 (
id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
c1 CHAR(150),
c2 CHAR(150),
c3 CHAR(150),
KEY(c1, c2, c3)
) ENGINE= MyISAM;
INSERT INTO t1 (c1, c2, c3) VALUES
('a', 'b', 'c'), ('b', 'c', 'd'), ('c', 'd', 'e'), ('d', 'e', 'f'),
('e', 'f', 'g'), ('f', 'g', 'h'), ('g', 'h', 'i'), ('h', 'i', 'j'),
('i', 'j', 'k'), ('j', 'k', 'l'), ('k', 'l', 'm'), ('l', 'm', 'n'),
('m', 'n', 'o'), ('n', 'o', 'p'), ('o', 'p', 'q'), ('p', 'q', 'r'),
('q', 'r', 's'), ('r', 's', 't'), ('s', 't', 'u'), ('t', 'u', 'v'),
('u', 'v', 'w'), ('v', 'w', 'x'), ('w', 'x', 'y'), ('x', 'y', 'z');
INSERT INTO t1 (c1, c2, c3) SELECT c1, c2, c3 from t1;
INSERT INTO t1 (c1, c2, c3) SELECT c1, c2, c3 from t1;
INSERT INTO t1 (c1, c2, c3) SELECT c1, c2, c3 from t1;
CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
SHOW VARIABLES LIKE 'key_cache_block_size';
Variable_name Value
key_cache_block_size 1536
SET GLOBAL key_cache_block_size= @bug28478_key_cache_block_size;
DROP TABLE t1;

27
mysql-test/t/key_cache.test
View file

@ -219,4 +219,31 @@ set global key_cache_block_size= @my_key_cache_block_size;
set @@global.key_buffer_size=0;
select @@global.key_buffer_size;
#
# Bug#28478 - Improper key_cache_block_size corrupts MyISAM tables
#
SET @bug28478_key_cache_block_size= @@global.key_cache_block_size;
SET GLOBAL key_cache_block_size= 1536;
CREATE TABLE t1 (
id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
c1 CHAR(150),
c2 CHAR(150),
c3 CHAR(150),
KEY(c1, c2, c3)
) ENGINE= MyISAM;
INSERT INTO t1 (c1, c2, c3) VALUES
('a', 'b', 'c'), ('b', 'c', 'd'), ('c', 'd', 'e'), ('d', 'e', 'f'),
('e', 'f', 'g'), ('f', 'g', 'h'), ('g', 'h', 'i'), ('h', 'i', 'j'),
('i', 'j', 'k'), ('j', 'k', 'l'), ('k', 'l', 'm'), ('l', 'm', 'n'),
('m', 'n', 'o'), ('n', 'o', 'p'), ('o', 'p', 'q'), ('p', 'q', 'r'),
('q', 'r', 's'), ('r', 's', 't'), ('s', 't', 'u'), ('t', 'u', 'v'),
('u', 'v', 'w'), ('v', 'w', 'x'), ('w', 'x', 'y'), ('x', 'y', 'z');
INSERT INTO t1 (c1, c2, c3) SELECT c1, c2, c3 from t1;
INSERT INTO t1 (c1, c2, c3) SELECT c1, c2, c3 from t1;
INSERT INTO t1 (c1, c2, c3) SELECT c1, c2, c3 from t1;
CHECK TABLE t1;
SHOW VARIABLES LIKE 'key_cache_block_size';
SET GLOBAL key_cache_block_size= @bug28478_key_cache_block_size;
DROP TABLE t1;
# End of 4.1 tests

11
mysys/mf_keycache.c
View file

@ -173,7 +173,7 @@ static void test_key_cache(KEY_CACHE *keycache,
#endif
#define KEYCACHE_HASH(f, pos) \
(((ulong) ((pos) >> keycache->key_cache_shift)+ \
(((ulong) ((pos) / keycache->key_cache_block_size) + \
(ulong) (f)) & (keycache->hash_entries-1))
#define FILE_HASH(f) ((uint) (f) & (CHANGED_BLOCKS_HASH-1))
@ -329,7 +329,6 @@ int init_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
keycache->key_cache_mem_size= use_mem;
keycache->key_cache_block_size= key_cache_block_size;
keycache->key_cache_shift= my_bit_log2(key_cache_block_size);
DBUG_PRINT("info", ("key_cache_block_size: %u",
key_cache_block_size));
@ -352,7 +351,7 @@ int init_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
ALIGN_SIZE(hash_links * sizeof(HASH_LINK)) +
ALIGN_SIZE(sizeof(HASH_LINK*) *
keycache->hash_entries))) +
((ulong) blocks << keycache->key_cache_shift) > use_mem)
((ulong) blocks * keycache->key_cache_block_size) > use_mem)
blocks--;
/* Allocate memory for cache page buffers */
if ((keycache->block_mem=
@ -1807,7 +1806,7 @@ byte *key_cache_read(KEY_CACHE *keycache,
uint status;
int page_st;
offset= (uint) (filepos & (keycache->key_cache_block_size-1));
offset= (uint) (filepos % keycache->key_cache_block_size);
/* Read data in key_cache_block_size increments */
do
{
@ -1946,7 +1945,7 @@ int key_cache_insert(KEY_CACHE *keycache,
int error;
uint offset;
offset= (uint) (filepos & (keycache->key_cache_block_size-1));
offset= (uint) (filepos % keycache->key_cache_block_size);
do
{
keycache_pthread_mutex_lock(&keycache->cache_lock);
@ -2081,7 +2080,7 @@ int key_cache_write(KEY_CACHE *keycache,
int page_st;
uint offset;
offset= (uint) (filepos & (keycache->key_cache_block_size-1));
offset= (uint) (filepos % keycache->key_cache_block_size);
do
{
keycache_pthread_mutex_lock(&keycache->cache_lock);