From b602127bf0225b7a33b44c1d7c7e1f06f8f4dee7 Mon Sep 17 00:00:00 2001 From: Sergey Vojtovich <svoj@sun.com> Date: Mon, 22 Mar 2010 16:30:27 +0400 Subject: [PATCH] BUG#51868 - crash with myisam_use_mmap and partitioned myisam tables Queries following TRUNCATE of partitioned MyISAM table may crash server if myisam_use_mmap is true. Internally this is MyISAM bug, but limited to partitioned tables, because MyISAM doesn't use ::delete_all_rows() method for TRUNCATE, but goes via table recreate instead. MyISAM didn't properly fall back to non-mmaped I/O after mmap() failure. Was not repeatable on linux before, likely because (quote from man mmap): SUSv3 specifies that mmap() should fail if length is 0. However, in kernels before 2.6.12, mmap() succeeded in this case: no mapping was created and the call returned addr. Since kernel 2.6.12, mmap() fails with the error EINVAL for this case. mysql-test/r/partition.result: A test case for BUG#51868. mysql-test/t/partition.test: A test case for BUG#51868. storage/myisam/mi_delete_all.c: _mi_unmap_file() is compressed record format specific, which is read-only. As compressed MyISAM data files are read-only, we must never use _mi_unmap_file() in mi_delete_all_rows(). storage/myisam/mi_dynrec.c: Make myisam mmap code more durable to errors: - set file_read/file_write handlers if mmap succeeded; - reset file_read/file_write handlers on unmap. storage/myisam/mi_extra.c: Moved file_read/file_write handlers initialization to mi_dynmap_file(). storage/myisam/myisamdef.h: Added mi_munmap_file() declaration. --- mysql-test/r/partition.result | 11 +++++++++++ mysql-test/t/partition.test | 13 +++++++++++++ storage/myisam/mi_delete_all.c | 2 +- storage/myisam/mi_dynrec.c | 31 +++++++++++++++++++++++++++++-- storage/myisam/mi_extra.c | 5 ----- storage/myisam/myisamdef.h | 1 + 6 files changed, 55 insertions(+), 8 deletions(-) diff --git a/mysql-test/r/partition.result b/mysql-test/r/partition.result index 08357795046..23a485dc5ed 100644 --- a/mysql-test/r/partition.result +++ b/mysql-test/r/partition.result @@ -2088,4 +2088,15 @@ SELECT 1 FROM t1 JOIN t1 AS t2 USING (a) FOR UPDATE; 1 1 DROP TABLE t1; +# +# BUG#51868 - crash with myisam_use_mmap and partitioned myisam tables +# +SET GLOBAL myisam_use_mmap=1; +CREATE TABLE t1(a INT) PARTITION BY HASH(a) PARTITIONS 1; +INSERT INTO t1 VALUES(0); +FLUSH TABLE t1; +TRUNCATE TABLE t1; +INSERT INTO t1 VALUES(0); +DROP TABLE t1; +SET GLOBAL myisam_use_mmap=default; End of 5.1 tests diff --git a/mysql-test/t/partition.test b/mysql-test/t/partition.test index 0cbe389dadd..22124cc1847 100644 --- a/mysql-test/t/partition.test +++ b/mysql-test/t/partition.test @@ -2081,4 +2081,17 @@ INSERT INTO t1 VALUES (6,8,10); SELECT 1 FROM t1 JOIN t1 AS t2 USING (a) FOR UPDATE; DROP TABLE t1; + +--echo # +--echo # BUG#51868 - crash with myisam_use_mmap and partitioned myisam tables +--echo # +SET GLOBAL myisam_use_mmap=1; +CREATE TABLE t1(a INT) PARTITION BY HASH(a) PARTITIONS 1; +INSERT INTO t1 VALUES(0); +FLUSH TABLE t1; +TRUNCATE TABLE t1; +INSERT INTO t1 VALUES(0); +DROP TABLE t1; +SET GLOBAL myisam_use_mmap=default; + --echo End of 5.1 tests diff --git a/storage/myisam/mi_delete_all.c b/storage/myisam/mi_delete_all.c index e2bbb04ab3c..7c3ed178c4c 100644 --- a/storage/myisam/mi_delete_all.c +++ b/storage/myisam/mi_delete_all.c @@ -55,7 +55,7 @@ int mi_delete_all_rows(MI_INFO *info) flush_key_blocks(share->key_cache, share->kfile, FLUSH_IGNORE_CHANGED); #ifdef HAVE_MMAP if (share->file_map) - _mi_unmap_file(info); + mi_munmap_file(info); #endif if (my_chsize(info->dfile, 0, 0, MYF(MY_WME)) || my_chsize(share->kfile, share->base.keystart, 0, MYF(MY_WME)) ) diff --git a/storage/myisam/mi_dynrec.c b/storage/myisam/mi_dynrec.c index 6518d874f4f..09152f8d013 100644 --- a/storage/myisam/mi_dynrec.c +++ b/storage/myisam/mi_dynrec.c @@ -94,6 +94,34 @@ my_bool mi_dynmap_file(MI_INFO *info, my_off_t size) madvise((char*) info->s->file_map, size, MADV_RANDOM); #endif info->s->mmaped_length= size; + info->s->file_read= mi_mmap_pread; + info->s->file_write= mi_mmap_pwrite; + DBUG_RETURN(0); +} + + +/* + Destroy mmaped area for MyISAM handler + + SYNOPSIS + mi_munmap_file() + info MyISAM handler + + RETURN + 0 ok + !0 error. +*/ + +int mi_munmap_file(MI_INFO *info) +{ + int ret; + DBUG_ENTER("mi_unmap_file"); + if ((ret= my_munmap(info->s->file_map, info->s->mmaped_length))) + DBUG_RETURN(ret); + info->s->file_read= mi_nommap_pread; + info->s->file_write= mi_nommap_pwrite; + info->s->file_map= 0; + info->s->mmaped_length= 0; DBUG_RETURN(0); } @@ -112,8 +140,7 @@ void mi_remap_file(MI_INFO *info, my_off_t size) { if (info->s->file_map) { - VOID(my_munmap((char*) info->s->file_map, - (size_t) info->s->mmaped_length)); + mi_munmap_file(info); mi_dynmap_file(info, size); } } diff --git a/storage/myisam/mi_extra.c b/storage/myisam/mi_extra.c index f0ddc15b325..d861b2af6cf 100644 --- a/storage/myisam/mi_extra.c +++ b/storage/myisam/mi_extra.c @@ -364,11 +364,6 @@ int mi_extra(MI_INFO *info, enum ha_extra_function function, void *extra_arg) DBUG_PRINT("warning",("mmap failed: errno: %d",errno)); error= my_errno= errno; } - else - { - share->file_read= mi_mmap_pread; - share->file_write= mi_mmap_pwrite; - } } pthread_mutex_unlock(&share->intern_lock); #endif diff --git a/storage/myisam/myisamdef.h b/storage/myisam/myisamdef.h index 1aa900061f3..962155e884c 100644 --- a/storage/myisam/myisamdef.h +++ b/storage/myisam/myisamdef.h @@ -762,6 +762,7 @@ int mi_open_datafile(MI_INFO *info, MYISAM_SHARE *share, const char *orn_name, int mi_open_keyfile(MYISAM_SHARE *share); void mi_setup_functions(register MYISAM_SHARE *share); my_bool mi_dynmap_file(MI_INFO *info, my_off_t size); +int mi_munmap_file(MI_INFO *info); void mi_remap_file(MI_INFO *info, my_off_t size); /* Functions needed by mi_check */